Corr Starch Adhesiveman

 

       l        h      a      c      r      u      a       t      n        S     a      g       M      s      n        i      e       t      v      a       i      g     s      u     e      r       h      r        d      o        C      A

 

Corn Products International, Inc. Quality Policy Policy on Products Products,, Services and Customer Relations It is the policy of Corn Products International, Inc., to provide products that not only meet applicable governmen governmentt quality and safety standards, standards, but but also seek to meet meet evolving customer customer expectationss for quality expectation quality,, value and service; and to assure assure the the accuracy accuracy and propri propriety ety of all all labeling, advertising, and other representations representations we make concerning concerning our products products and services.

 

INTRODUCTION

TABLE OF CONTENTS

This manual is intended as a resource on starch, its

Background  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 The History of Starch . . . . . . . . . . . . . . . . . . . . . . .3 The Corn Wet Milling Process . . . . . . . . . . . . . . . . .4 The Role of Corn . . . . . . . . . . . . . . . . . . . . . . . . . .6 Starch Basics for Corrugated Board . . . . . . . . . . . . .7

relationship relationshi p to, and use in corrugating. It is designed to make it easier to respond quickly and effectively to adhesive and machine machine problems. problems. The information information presented is based upon actual field and laboratory work. It should not be viewed as providing advice or solutions to particular applications, each of which is unique and not susceptible to general advice. We encourage you to call your representative at Corn Products U.S., CASCO, Inc., or CPIngredientes CPIngredientes to discuss your specific situation. We will be happy to lend our support.

Viscosity  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Low Viscosity . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 High (Thi Heavy .Adhesive) Adhe .9 EffectsViscosity of Shear(Thick, onck, Viscosity . . .sive) . . . . .. .. .. .. .. .. .. .. .. .9 The Temperature Temperature Viscosity Control System . . . . . . . .10 Viscosity/Time Relationship Relationship . . . . . . . . . . . . . . . . .11 Viscosity/Resin Relationship Relationship . . . . . . . . . . . . . . . . .11 Microbiological Degradation Degradation . . . . . . . . . . . . . . . . .11 Care with Biocides . . . . . . . . . . . . . . . . . . . . . . . .11 Gelatinization Temper Temperature ature  . . . . . . . . . . . . . . . . . . . .12 Gel Temperature Too Too High . . . . . . . . . . . . . . . . . . .12 Gel Temperature Temperature Too Low . . . . . . . . . . . . . . . . . . .12 Gel Temperature/Time Temperature/Time Relationship Relationship . . . . . . . . . . . .12 Determination of Caustic Concentrati Concentration on In Liquid Caustic . . . . . . . . . . . . . . . . . . . . . .12 Corrugating Additives  . . . . . . . . . . . . . . . . . . . . . . . .13 Penetrating Penetra ting Aids . . . . . . . . . . . . . . . . . . . . . . . . .13

Corporate Headquarters Corn Products U.S. 5 Wes Westbroo tbrookk Corporate Center Center Westchester, IL 60154 United States (800) 443-2746 www.cornproductsus.com

Toronto Casco, Inc. 401 The West Mall, 2nd Floor Etobicoke Etobi coke,, Onta Ontario rio M9C 5P7 Canada (416) 620-2300 (Toronto) (514) 694-4700 (Montreal/Eastern Canada) www.casco.ca

CPIngredientes, S.A. de C.V C.V.. Av.. Mariano Otero #1249, Floor Av Floo r 9 Torre Atlantico Rinconad Rin conadaa del Basque Basque 44530 Guadalajara, Jalisco

Mexico (33) 3884-9000 ext. 3520 www.cpimex.com

Antifoam Agents . . . . . . . . . . . . . . . . . . . . . . . . .13 Liquid Additives . . . . . . . . . . . . . . . . . . . . . . . . .13 Resins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 . 13 Corrugating Processes/Systems/E Processes/Systems/Equipment quipment .  . . . . . . . . . .15 Stein Hall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Jet Cook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 High Shear . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 No-Carrier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Starch Properties and Testing  . . . . . . . . . . . . . . . . . .17 Alkali (Caustic) Sensitivity Sensitivity . . . . . . . . . . . . . . . . . .17 Measuring Viscosity of Finished Finis hed Starch Starch Adhesive Adhesive . . . . . . . . . . . . . . . . 17 Calibrating the Stein Hall Cup . . . . . . . . . . . . . . . .17 Gelatinization Temperature Temperature . . . . . . . . . . . . . . . . . .17 Microbiological Testing Testing . . . . . . . . . . . . . . . . . . . . .17 Starch Solids Concentration Concentration . . . . . . . . . . . . . . . . .17 Board Testing  . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Quality Monitoring and Control at the Adhesive Station  . . . . . . . . . . . . . . . . . . . . . .21 Statistical Statis tical Process Process Control Control . . . . . . . . . . . . . . . . . .21 Troubleshooting Common Troubleshooting Corrugatin Corrug ating g Probl Problems ems .  . . . . . . . . . . . . . . . . . . . . . .23 Diagnosing Diagnosin g Viscosity Problems . . . . . . . . . . . . . . . .23 Diagnosing Diagnosin g Typical Gel Temperature Temperature Problems . . . . .26 Diagnosing Diagnosin g Corrugating Equipment and Board Quality Problems . . . . . . . . . . . . . . . . . .27 Diagnosing Diagnosin g Warp Problems . . . . . . . . . . . . . . . . . .31 Appendices  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34 Glossary  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

 

CORRUGATED MAKES IT HAPPEN FOR

2

FARMING

 

Background The History of Starch The first uses of starch stretch back to the ancient Egyptians and Chinese. They were quite adept at using starches, a fact duly recorded in Cato’s Treatise written in 184 B.C. It was much later in Europe, however, however, that the industry flourished. The source of grain supply then was wheat and rice. As demand for starch increased, other raw materials, including potatoes, were tried. It was the English who brought the knowledge of producing starch to the New World, where, after the Revolutionary War, numerous small potato and wheat starch plants were operating in the eastern United States. However, the price of wheat and potatoes was rising to the point where profit margins were seriously endangered. The search substitute materials resulted America’s most for abundant cropraw as the answer, and theinfirst corn starch factory was built in 1844 in Jersey City, City, New Jersey.. From that point on, the industry grew by leaps Jersey and bounds. In 1906, New York Glucose and the Glucose Trust merged into Corn Products Refining Company under the management of E.T. Bedford.

Corn Products International, Inc., Leads the Way Through the decades, Corn Products International continues growing. Today, we operate nine corn refining facilities in North America. Corn starches and sweeteners produced in these plants are used in a wide variety of  food and industrial products. Our long history with starch and experience with the corrugating industry affords corrugators many advantages. We have consistently sought new and innovative methods of meeting the changing needs of  corrugators. Such efforts have led to the development of quality modified and unmodified starches that corrugators have come to expect. Our commitment to the corrugating industry is further evidenced by our pledge to excellence in technical services, sales representation and engineering assistance.

3

 

The Corn Wet Milling Process The objective of processing corn is to separate the kernel  into its component parts with maximum purity. purity. The five basic products that result are starch, steepwater, steepwater, germ, feed and gluten. The 40-hour steeping process softens the corn, removes some solubles (steepwater), and breaks the bond connecting starch, gluten, germ and fiber. Germ, presses gluten and areThe dewatered and dried by use of filters, and fiber dryers. germ is further processed to recover oil, while the remaining fiber is returned for feed. Starch slurry is converted to food and industrial grade starches for industrie industriess including corrugating. It is dewatered in centrifuges to produce a starch “cake.” This is then dispersed into a stream of heated air and flash dried to a finished moisture of about 9–12.5 percent. The dried starch is pneumatically conveyed to a storage silo where it can be loaded into bulk railcars, bulk trucks or packed into 50- or 100-pound bags, or super sacks. During the drying process, it is common for corn wet milling plants to maintain the moisture of about 9–12.5 percent. Great care must be taken to prevent the starch from overheating in the t he presence of moisture. If the process is not monitored closely, a starch product with abnormally high sensitivity to caustic soda may result. If the starch is to be further refined into a sugar, it is processed in a refinery. refinery. Customers use dextrose dextrose,, fructose and corn syrup sugars in many food and beverage and industrial applications applications..

4

Many factors affect the consistent production of  starch. As with any natural raw material, properties of corn can be affected by temperature, hours of sunlight, humidity, rainfall, year of planting, soil moisture, plant population and fertilization rate. Different corn varieties can also result in varying starch properties. Corn varieties that contain all branched starch molecules are called waxy maize. The types of corn that contain unusually large quantities of linear starch molecules are called high amylose hybrids. Starches derived from these two hybrids have vastly different properties that offer benefits in end-use applications app lications.. Waxy maize starch tends to resist retrogradation, making making it ideal for certain food applications such as puddings or in textiles because it produces a clear film. Conversely, Conversely, high amylose hybrids invert rapidly, which works well for processes including fiberglass sizing or cotton-polyester blend sizing. Normally, corn starch is composed of two molecular Normally, species. Amylose, a linear non-branched type of molecule, makes up about 25 2 5 percent of the starch in convention conventional  al  corn starch. Amylopectin, the branched molecule in starch, accounts for the t he remainder, remainder, or approximately 75 percent.

 

The Corn Wet Milling Process Corn

Steeping

Germ

Milling & Screening

Corn Oil 

Feed & Dietary Fiber

Steepwater

Germ Meal 

Starch Separation

Corn Syrup

Gluten Feed

Starch Slurry

Syrup Refining

High Fructose Corn Syrup

Industrial  Starches

Starch Drying

Food Starches

Dextrose Family

 

The Role of Corn smaller granules have reduced amounts of amylose, the linear molecule fraction in starch.2 Larger starch granules gelatinize more easily than small particles.3 It also is known that starches with lower gel temperature than entire high quantities of amylose yield much higher gelatinization temperatures than conventional corn starch. (See Figure 2.)

There are factors that affect the makeup of corn. For years, seed-corn suppliers have worked to improve the characteristics of the corn plant. Corn hybrids have increased resistance resistance to disease and pests and improved yields. These improvements improvements benefit all industries that use corn by-products. For corrugators, the most important properties are viscosity and gelatinization point. These properties can vary from corn crop to corn crop.

When heated in water, native starch granules, regardless

Data shows the natural gelatinization temperature varies depending depending on the t he climate or growing region of 1 the world. (See Figure 1.) Process modifications may be necessary to compensate for raw material variations. Even granule size (diameter) is affected by environmen environmental  tal  factors. Granule size is important since it is known that

of molecular type, hydrate (absorb water), increase in size and thicken to form a viscous liquid, gel or paste. This single property is probably the most important characteristic of the starch and is relied upon to provide thickening. In the corrugating industry industry,, this gelatinizing property of  starch is encouraged by the addition of caustic c austic soda and used effectively to suspend or carry pearl starch that has not been gelatinized. FIGURE 2

FIGURE 1 Geographic Relationship to Gelatinization Temperature

Reported Gelatinization Temperatures of Conventional Corn Starch and High Amylose Starches

Gelatinization of  Corn Starch

Geographic Location and Growing Conditions

Identification of  Starch Type

Gelatinization Range of Starch Type

(Unmodified)

(Initiation, Midpoint, Completion)

Location A

143-158˚F [61.7-70.0˚C]

Conventional Corn

Location B

147-165˚F [63.9-73.9˚C]

High Amylose Corn

143˚F 158˚F 167˚F   [61.7˚C] [70.0˚C] [75.0˚C]

 

 153˚F 176˚F (Note) [67.2˚C] [80.0˚C]

Note: Complete gelatinization of high-amylose starch is not affected in boiling water, 212˚F [100˚C]. It has been stated that high amylose requires pressure for complete gelatinization.

FIGURE 3

The Corrugating Process S. F. to bridge

Liner preheater 378F [192.2C]

236-266F  [113.3-130.0C]

180-190F  [82.2-87.8C]

Pressure roll  180-210F  [82.2-98.9C]

6

Medium preconditioning roll 250F [121.1C]

Greenline steam shower

370F  [187.8C] Doctor roll  370F  [187.8C]

Adjustable wrap roll 

Open steam shower

Starch applicator roll 

Starch Dance roll  Open steam shower

Footnotes: 1. F.R. Earle, “Protein and Oil in Corn: Variation by Crop Years Years from 1907 to 1972”, Cereal Chem., Vol 54(1), 54(1), pp. 71-79. 2. R.L. Whistler, J.N. J.N. BeMiller and E.F. E.F. Paschall, Starch: Chemistry and Technology  Technology , 2nd Edition, (Academic Press, 1984) Chapter III, pp. 34 & 36, Jack C. Shannon and Douglas L. Garwood, Contributing Authors. 3. R.W. Kerr, Chemistry and Industry of Starch, 2nd Edition, (Academic Press, Inc.,1950) Chapter I, p. 3

 

 

The primary value of borax is to buffer the caustic soda present in the formula. It also provides p rovides viscosity control  and adds tack to the finished adhesive. adhesive. For equivalent amounts of borax for starch formulations, see Appendix A.

Starch Basics for Corrugated Board For 2005, the value of the corrugated board market in the U.S. is estimated to be over $24 billion. Corrugated board is made up of liners and the fluted medium. Many weights, thicknesses and combinations of liners and medium are used for different applications. applications. The principles of manufacture are simple. (See Figure 3.)

Generally, 15–20 percent Generally, p ercent of the starch is fully cooked in part of the water with caustic to provide a carrier for the pearl starch. Starch solids levels usually are 23–35 percent to achieve finished adhesive viscosity of 30–50 Stein Hall seconds. After the adhesive is applied to the

Starting at the single facer, flat corrugating medium is softened with heat and moisture and passed between a set of corrugating rolls to form it into flutes. Adhesive is applied to the flute tips on one side of the medium. Then, a single facer linerboard is brought into contact with the fluted medium under heat and pressure to produce a single facer web. This web is conveyed to the double backer station where adhesive is applied to the exposed flute tips and the double backer liner is applied. The combination is finally conveyed over a series of hot plates to set the adhesive.

flute tips and heated, the pearl starch gelatinizes in place. When the starch swells and gelatinization begins, a green bond is formed. Nearly all of the corrugated board produced today is bonded with a starch-based adhesive. adhesive. Since the quality and bonding properties of the starch directly affect final board quality quality,, decisions regarding starch should be made carefully and treated with importance in the process. Pearl starch, or unmodified starch, typically has been the key product used for starch adhesive. However, with the introduction of high performance papers and the increased use of recycled paper, the porosity of the corrugated medium and liners has changed. Therefore, Therefore, the adhesive must change, too. Modified, or carrier, starches, when used in conjunction with pearl starch, allow an increase in solids for better bonding and the ability to achieve higher machine machine speeds.

Modern corrugating machines can run at speeds in excess of 1,200 feet per minute, depending on the type of board being produced. These high speeds are possible because of corn starch’s ability to gelatinize and produce high viscosities at the glue line. A mixture of pearl starch, borax, caustic soda and water is suspended in a paste of cooked starch. The addition of  caustic soda helps gelatinize the starch. An increase in the amount of caustic soda, based on the total starch, will lower the gel temperature of the entire adhesive.

Bridge S. F. liner Adjustable wrap roll   

Preheater 36" 150-160F  [65.6-71.1C]

D. F. Liner

Roll stand

Adjustable wrap roll  Preheater 36"

Hold down Rider roll  roll 

Doctor roll  Starch

Starch applicator roll  Preheater 18" 180-210F  [82.2-98.9C] 7

 

CORRUGATED MAKES IT HAPPEN FOR

8

SHIPPING

 

Viscosity In the corrugating industry, the term viscosity is used to describe adhesive’s flowability. flowability. (Tests for measuring

In mixing systems, mixing blades shear the adhesive to a workable viscosity. viscosity. When an adhesive formula is

viscosity can be found on page 17.)

developed, the mix times are calculated to perform this task correctly. When the mix times t imes are changed, quality of the finished adhesive will vary.

Low Viscosity When adhesive paste is too thin, or has low lo w viscosity, the water tends to “wick” into the medium. This wicking action may remove the needed water from the glue line, which means the pearl starch may not have enough water to gelatinize completely. Many times the board will be dry and brittle coming off the corrugator, or may become brittle as it stack cures. If a pin adhesion test is performed on a sample of this board, low numbers will result. There may be very little fiber pull and the glue line will have an amber appearance. Since the bond is marginal, one solution is to open the glue settings on the machine to deliver more adhesive to the glue line. The downside downside to applying more adhesive is the potential for warp, washboarding, higher starch consumption and slower machine speeds.

High Viscosity (Thick, Heavy Adhesive) When the adhesive is too thick (high viscosity), it tends to sit on top of the flute tip, penetrating the medium and glue line very slowly. This will lead to a soft, wet board coming from the corrugator. It is difficult to print on wet board and it is hard to convert in the finishing department. Starch consumption will also increase because of the wide glue lines associated with thick adhesive.. Adhesive flowability is reduced in the glue adhesive pans, which pushes adhesive to the back of the pans and allows heat to build up. This usually leads to gelling problems at the single facer.

The secondary mixer blades must be properly placed and in good repair to prevent areas of over-agitation. Missing or broken blades will add mixing time and may reduce the flexibility of the formula. The storage tanks should have agitators operating on timers. Agitators should be set to mix for five minutes out of every 30 minutes. These agitators also should operate if  the Temperature Viscosity Control (TVC) system calls for heat. Temperature Temper ature is very important when taking a viscosity reading. The viscosity of the adhesive will vary proportionally with the temperature of the adhesive.. As the temperature goes up, the viscosity will  adhesive drop (become thinner). Conversely, as the temperature decreases, the viscosity will increase (become thicker). This inverse relationship of viscosity to temperature is approximately 10 percent for every 2˚F [1.1 [1.1˚C] ˚C] change. (See Figure 4.) The piping system used in the plant should not have dead ends. Fewer elbows and turns t urns help reduce friction and pressure buildup within the lines. The lines should be pitched to ensure adequate drainage drainage for cleanups. The pumps (often positive displacement pumps) used to transfer adhesive from the mixer to storage tanks and from storage tanks to corrugator can cause unwanted shearoperating shear. . It is important to have the proper size pump at the correct rpm. A plant’s starch supplier should be able to help calculate system needs.

Overflowing adhesive and poor transfer of the adhesive from the glue roll is associated with high viscosity adhesive. On some of the new, high speed single facers, the machine will shut down if the viscosity is too high.

Effects of Shear on Viscosity Shear is the mechanical action of breaking down the adhesive resulting in reduced viscosity. Shear can occur at the mixers, pumps, pipes, elbows or valves, and at the actual corrugator. 9

 

FIGURE 4

Temperature - Viscosity Correction Table (for Stein Hall Viscosity)

   )    l    l   a    H     n    i   e    t    S    (   y    t    i   s   o   c   s    i    V

90F  [32.2C]

92F  [33.2C]

94F  [34.4C]

96F  [35.6C]

98F  [36.7C]

100F  [37.8C]

102F  [38.9C]

104F  [40.0C]

106F  [41.1C]

108F  [42.2C]

110F  [43.3C]

42

38

34

31

28

25

22

20

18

16

15

44

40

36

32

29

26

23

21

19

17

15

46

41

37

34

30

27

24

22

20

18

16

48

43

39

35

31

28

26

23

21

19

17

50

45

41

36

33

30

27

24

22

19

17

52

47

42

38

34

31

28

25

22

20

18

54

49

44

39

35

32

29

26

23

21

19

56

50

45

41

37

33

30

27

24

22

20

58

52

47

42

38

34

31

28

25

22

20

60

54

49

44

39

35

32

29

26

23

21

62

56

50

45

41

37

33

30

27

24

22

64

58

52

47

42

38

34

31

28

25

22

66

59

53

48

43

39

35

32

28

26

23

68

61

55

50

45

40

36

33

29

26

24

70

63

57

51

46

41

37

33

30

27

24

72

65

58

52

47

43

38

34

31

28

25

74

67

60

54

49

44

39

35

32

29

26

76

68

62

55

50

45

40

36

33

29

26

78

70

63

57

51

46

41

37

34

30

27

80

72

65

58

52

47

43

38

34

31

28

82

74

66

60

54

48

44

39

35

32

29

84

76

68

61

55

50

45

40

36

33

29

86

77

70

63

56

51

46

41

37

33

30

88 90

79 81

71 73

64 66

58 59

52 53

47 48

42 43

38 39

34 35

31 31

92

83

75

67

60

54

49

44

40

36

32

94

85

76

69

62

56

50

45

40

36

33

96

86

78

70

63

57

51

46

41

37

33

If air pumps are to be used to circulate the adhesive to and from the machine, machine, proper air pressure is essential. Most air pumps operate at 40 to 60 psi, depending upon the distance to pump. Too much air pressure will force the adhesive through the lines and cause shear. Valves in the lines must be inspected regularly. A worn valve may appear open when it is only partially open, causing shear of the adhesive. 10

The Temperature Viscosity Control System To control the adhesive temperature in storage properly, a Temperature Viscosity Control (TVC) system is required. Typically, the system uses a small tank of heated water positioned slightly above and between the adhesive storage tanks. Water from this tank is circulated through coils inside the storage tanks at the same time agitators are moving adhesive. The water should be heated to a

 

temperature 10˚F [5.6˚C] lower than the lowest gel temperature of the adhesive in storage. When the temperature of the adhesive falls below 100˚F [37.8˚C], the TVC system should activate automatically aut omatically.. Probes inside the TVC water tank and storage tanks monitor temperature.

Some resins will react with borax in the formula causing a change in viscosity. Using the correct amount of resin in the formula is critical. The resin supplier should be contacted for proper addition addition rates and/or limitations. limitations.

If the water temperature becomes too high (higher than the gel temperature of the adhesive), the adhesive will begin to gelatinize on the coils. When this happens, the heat transfer from the water in the coils to the starch

Microbiological Degradation

is reduced, which increases the agitation time of the adhesive. This can result in low viscosity. The longer it takes for the temperature to rise, the longer the storage tank agitators must run, and the higher the risk of shear. Plants that have complete steam shutdown on weekends rely on electric units to heat TVC water. This is an important consideration consider ation in new installations to insure proper adhesive viscosity control.

Viscosity/Time Relationship The length of time the adhesive is held in storage can be critical. Over time, the raw portion of the adhesive will begin to separate from the cooked portion. This causes viscosity to drop. Fast turnover of the adhesive is the best solut ion. solution. Reducing the amount of material for storage during down periods is also wise.

Viscosity/Resin Viscosity/ Resin Relations Relationship hip To make adhesive water resistant, you must add resin. This creates a chemical reaction when the mixture is heated on the corrugator. The result produces a water-resistant bond. The degree of water resistance is related to the ratio of resin solids to starch. However However,, it is difficult to generalize about the amount of resin needed because resin solids vary dramatically. Never mix resin-treated adhesive with adhesive in storage. When resin is added to a batch of adhesive, it is advisable to use all of the adhesive as soon as possible. The adhesive’s resin potency will last approximately eight hours after a batch is made. After that, the resin loses the ability to react with the starch and viscosity breakdown begins, affecting the entire batch. Also, resins have a finite shelf life.

Starch, a carbohydrate, is often consider considered ed food for bacteria. It has been found that some bacteria will survive, and may even thrive, in a strong alkaline medium such as starch-based corrugating adhesives. If the bacteria population increases to, or exceeds, 10,000 colony c olony forming units (cfu) per gram, starch adhesive could show viscosity loss. This results from the gelled starch being attacked by bacteria and converted to a soluble carbohydrate carbohydrate,, which will lower viscosity viscosity.. At levels greater than 1,000,000 cfu per gram, an odor may also develop. However, odor alone should not be considered consider ed an indicator of microbiological growth. When microbial problems are suspected, microbiological testing can be a valuable tool. Test laboratories generally require an aseptically obtained sample of the corrugating adhesive to achieve meaningful results. Contact your biocide supplier and request a test of the plant’s adhesive.

Care With Biocides To prevent microbiological microbiological growth, biocides b iocides should be used with care. Most manufacturers manufacturers recommend recommend changing the biocide regularly to prevent the growth of a colony that may resist res ist the action of a particular biocide. biocide. (See Appendix B.) It is recommended that the entire adhesive system be cleaned twice per year using a commercially available industrial strength cleaner and commercial household bleach, or a treatment from your biocide supplier. supplier. The lines to and from the machine also should be flushed and cleaned. If the adhesive system uses bulk b ulk starch, the discharge chute should be cleaned or changed since it is a breeding ground for bacteria. Details on system cleaning should be provided by the biocide supplier.

Resin should be added slowly to the adhesive, usually during the final mix. Adding the resin too fast can cause viscosity changes. It is not advisable to add resin to the storage tanks because viscosity changes can occur in storage, to the point that the adhesive will be unable to pump. In addition, the storage tank agitators are not designed to blend resin, and permanent damage can occur.

11

 

Gelatinization Temperature Gelatinization temperature, temperature, or gel temperature, is the temperature at which the adhesive begins to thicken t hicken and develop its bonding properties. Although it is often expressed as a single temperature temperature unit (˚F or ˚C), in reality it is a temperature range dependent dependent upon the molecular size and composition of the starch. st arch. The natural gelatinization temperature of corn starch is generally too high for normal corrugating operation. Running an adhesive with high gel temperature could affect bonding, especially at the double backer. Machine speed could also be affected. Addition of caustic soda suppresses the gelatinization temperature t emperature,, thus providing corrugators the flexibility to set the gel temperature at a desirable level for the individual machine conditions and paper combinations combinations.. Gel temperature is measured by simply heating the adhesive as it is stirred with a glass thermometer thermometer.. When the paste begins to thicken (gel), the temperature that appears on the thermometer is recorded. (See Appendix C.)

Gel Temperature Too High If the gel temperature is too high, there may not be enough heat present to gelatinize all the starch granules. This will result in a white glue line and a poor bond. The speed of the corrugator must be reduced to achieve an acceptable bond, particularly on double wall board. The dry end operators also may notice wet or soft board coming off the machine.

Gel Temperature Too Low If the gel temperature is too low, several conditions may result. The adhesive will gel before it has a chance to penetrate into the paper. This may result in brittle board, dry bond, raspy-feeling glue lines and cracking board. There also may be severe gelling on the t he fingers of the single facer or gelling in the pans.

12

Gel Temperature/Time Relationship The gel temperature will rise the t he longer the adhesive is held in storage. This happens because over time the starch will absorb some of the free caustic present in the adhesive. Periodic Periodic checks of the gel temperature will prevent unwanted high temperatures at the double backer glue station.

Determination of Caustic Concentration in Liquid Caustic (Hydrometer Method) The caustic concentration of liquid caustic can be determined by utilizing a caustic specific gravity g ravity chart and specific gravity spindle. Equipment needed is a specific gravity spindle, a clear 500-mL plastic cylinder and a specific gravity concentration chart. (See Appendix D.) Fill the plastic cylinder so that it is about 2/3 full with liquid caustic. Make sure the sample is at or above room temperature. Gently insert the spindle into the liquid so that it floats freely without touching the sides or the bottom. The spindle stem has graduated marks (specific gravity units), and the reading is taken at the point where the liquid level intersects the spindle stem. The specific gravity reading is applied to the chart to determine the percent caustic (% NaOH) directly. For example, if the sample is 50% liquid caustic, the spindle reading will be 1.530. If the reading is higher, the caustic solution is higher than 50%. Similarly, if the reading is lower, the caustic solution is diluted with water and its concentration is less than 50%. (See Appendix D.)

 

Corrugating Additives Penetrating Aids

Liquid Additives

When dense liners and/or mediums are used, penetrating aids may help bonding by reducing the water surface tension, so the adhesive can penetrate the sheet. If a plant suspects that a penetrating aid would be beneficia beneficial, l, the plant should contact the t he starch supplier for assistance.

Liquid additives are often used to enhance the wet tack, or green bond, of starch-based adhesives. Green bond is the measure of an adhesive’s wet tack and the major factor affecting the potential machine speed of the corrugator. These products can potentially increase corrugator operating speeds. Although suited for any adhesive mixing system, liquid additives are an ideal choice for high shear mixing systems that may be equipped with liquid dosers. For liquid additive options, contact your starch supplier. supplier.

Antifoam Agents The use of antifoam agents is common with today’s corrugators. As machine speeds increase increase,, foam is often created in the glue pans as starch cascades off the metering roll and wiper blade. If the foaming becomes severe,, it can overflow the pan, causing higher than severe normal starch consumption; or it can transfer from the glue roll to the flute tips, causing poor bonding. Should foaming occur at the double backer, it could overflow onto the paper, resulting resulting in a poor bond on the double facer side.. For antifoam options, contact your starch supplier. side

Resins Resins are used in starch adhesive formulations to impart varying degrees of water resistance to corrugated board. The resins react with hydroxyl groups on starch and render the starch insoluble to water water.. Degrees of water resistance resistance,, ranging from moisture resistance to waterproof, depend on the functional use of the container. Various types of water soluble thermosetting resins are available to the corrugating corrug ating industry.. Ketone aldehyde-type resins are particularly well  industry suited for corrugating applications. They require caustic and heat in order to react. For resin options, contact your starch supplier supplier..

13

 

CORRUGATED MAKES IT HAPPEN FOR

14

CONSUMERS

 

Corrugating Processes/Systems/Equipment Starch plays an important role in the corrugating process, so the integrity of the starch production process is critical. Four processes are common in starch adhesive production: Stein Hall, Jet Cook, High Shear and No-Carrier methods. Basic adhesive preparation consists of  a cylindrical primary mixer with a low-speed, high-torque mixer situated above a secondary tank with a high-speed, lower-torque agitator. A drop valve generally controls the flow of adhesive from the primary p rimary mixer into the secondary tank. However, No-Carrier adhesives differ d iffer significantly in preparation since only one mixer tank is used and no gelatinization of starch occurs.

Stein Hall  This system uses a two-phase process. The first phase is referred to as the cook phase. Here, starch, water and caustic are combined to create a gelatinized starch adhesive.. This product is also referred to as the carrier adhesive carrier.. The second phase is the blend bl end phase where starch, water and borax are added together and mixed with the cooked portion to form a finished adhesive. (See Figure 5.)

FIGURE 5 Caustic mix tank

Secondary mixer Recirculation

Primary mixer

 

To storage

Pump

Steps: (1) Water primary and secondary; (2) Starch primary; (3) Add caustic to primary; (4) Cook primary; (5) Add borax to secondary; (6) Add starch to secondary; (7) Add cooling water wa ter to primary; (8) Drop primary into secondary; (9) Final mix; (10) Pump to storage

FIGURE 6 Starch

 

Water

Chemical tank 20 Gal. Raw

Slurry tank

Steam

Cooling column

 

Mixer

Jet Cook

Scales

Pump To storage

Carrier 190F  [87.8C]

The Jet Cook system is a modification of the Stein Hall  process using a single vessel horizontal mixer.

150F [65.6C]

With the Jet Cook system, all the water, caustic and borax are mixed together with approximately half of the total starch in a horizontal mixer. mixer. The amounts of caustic

Steps: (1) Raw starch water; (2) Raw starch; (3) Transfer to mixer; (4) Add chemicals; (5) Add carrier water; (6) Add starch carrier; (7) Jet cook carrier; (8) Final mix;

and borax are determined by the gel temperature that is needed for a given adhesive. This starch/water/chemical  slurry is then circulated through pipes and returned to the mixer.. Live steam is injected into the pipe, causing the mixer slurry to swell (gelatinize) as it is being pumped back into the mixing tank. tank. Monitored by an automatic viscometer viscometer,, the process continues until a given viscosity (set point) is reached. Upon reaching its set point, the steam is shut off and the remainder of the pearl starch is added to the adhesive. A timed mix then finishes the process. (See Figure 6.)

(9) Pump to storage

15

 

High Shear

FIGURE 7

The High Shear system is an improvement on the conventional convention al Stein Hall process.

Starch

When trying to achieve a high solids adhesive formula with the conventional Stein Hall system, the limiting factor is that high viscosities develop as the amount of  primary starch is increased. One way to overcome the high viscosity is to mechanically shear the cooked portion of  the formula. Using a vertical mixing tank with a mixing blade designed to shear the gelled starch, batches batc hes with higher solids can be made faster with better results. Different manufacturers manufacturers use different mixer and blade combinations to achieve the same results. Adhesive is usually made in a single vessel resting on weight sensors. Water is added (by weight) and heated to a set point. Some automatic systems compensate for condensation by adjusting the programmed ingredient ingredient weights to meet any changes caused by the added water. Other systems heat the water using a heat exchanger exchanger so no condensati condensation on is added to the t he programmed formula. Starch and caustic (usually 50% liquid) are added and mixed under high shear. Borax, secondary water and starch are then added and mixed for a cycle timed anywhere from 12 to 35 minutes. Some systems allow for up to 20 different formulas to be programmed into the system so customized adhesive can be made for different board combinations or special papers.

No-Carrier This process is very different from the others. No gelatinization of any of the starch takes place. In the No-Carrier process, starch, water, 50% liquid caustic caust ic and boric acid are used to “swell” the starch granule. This is accomplished by monitoring the viscosity of the adhesive adhesive.. All mixing of ingredients takes place in a lower mixer. (See Figure 8.)

16

Motor 40 hp

Water

To storage Scale

20,000 r.p.m.

High Shear Adhesive System

FIGURE 8 Bulk starch

Water Norcross viscometer

From liquid caustic storage

130F  [54.4F] Caustic tank

Scale hopper

Most automatic systems incorporate level controls in the storage tanks and automatically make a batch when needed. This allows for lower storage volumes, which results in fresher adhesive being used at the corrugator. One major advantage of the new High Shear mixing system is that it dramatically reduces adhesive preparation preparation time, freeing up manpower to be used in other plant operations.. Even though some of the systems are fully operations automatic, they still must be checked daily and put on a preventative maintenance schedule. (See Figure 7.)

Borax

Caustic

Caustic supply line

Boric acid Boric acid addition system

To storage Pump

Pump

130F [54.4C]; Steps: (1) Water; (2) Starch; (3) 130F [54.4C]; (4) Mix to X Norcross Units; (5) Add boric acid to terminate; (6) Final mix; (7) To storage No-Carrier Adhesive System

 

Starch Properties and Testing Alkali (Caustic) Sensitivity

A reading other than 15 seconds may indicate a plugged or enlarged opening, or the pins may have

One critical property of theconditions. starch is the ability to perform in alkali (caustic)

become bent. Carefully clean the orifice and check the volume between the pins. Recheck the flow of water. If it is not correct, replace the disk.

During the manufacturing process, starch granules can become damaged. When a sample of starch containing an excessive amount of damaged granules is mixed in a solution of caustic (alkali), the starch swells at too rapid a rate. This results in a viscosity that is higher than normal. There are several methods used to check for the alkali sensitivity of pearl starch. One is the settling test for unmodified starch. (See Appendix E.) This test can be accurate and reproducible with relatively inexpensive testing equipment. Minor deviations deviations from the procedure, or less than ideal conditions, may result in inaccurate results.

Gelatinization Temperature Gelatinization (gel) temperature will affect the corrugating operation and is frequently measured. Gel point is the temperature at which liquid l iquid adhesive is transformed into a semi-solid mass or gel. (See page 12 and Appendix C for test procedures.)

Microbiological Testing

There is a second, more rapid test for alkali sensitivity that is just as accurate as the settling test. However, this test uses a more costly Brookfield Viscometer. (See Appendix F.)

Measuring Viscosity of Finished Starch Adhesive There is one standard for measuring viscosity — Stein Hall seconds, which is calculated using a Stein Hall Cup. There are, of course, some plants and manufacturers who use other methods and tools for measuring viscosity. viscosity. Love Cups, Zahn Cups, Brookfield Viscometers, Norcross Viscometers and Dynatrol Viscometers are some of the other methods and tools that are used. Some have individ individual charts for flowability, but most are converted to SteinualHall seconds. The Stein Hall Cup is a brass cylinder with a specific size orifice in the bottom, and two brass pins located on the inside of the cylinder wall. The distance between the two pins will hold a volume of exactly 100 ml of liquid. The cup is filled with adhesive and allowed to flow through the opening. The elapsed time it takes the adhesive to move from pin to pin is the viscosity in seconds.

Calibrating the Stein Hall Cup The Stein Hall Cup must be calibrated properly to give an accurate viscosity reading. Measuring water flow from pin to pin is the best way to check calibration. Water should flow from pin to pin, through the orifice, in exactly 15 seconds.

Bacterial growth in starch adhesives is detrimental  because it causes molecular breakdown. If the growth reaches a certain point, viscosity will be drastically reduced, making the adhesive unusable. This growth cannot be measured at the plant site. Typically, adhesive samples are sent to a laboratory capable of measuring bacterial growth. The plant’s biocide supplier can assist in arranging testing. Laboratory reports speak in terms of colony forming units (cfu) per gram. When the cfu level reaches 10,000 cfu/g, it is advisable to clean the system. (See page 11 and Appendix B.)

Starch Solids Concentration High solids (starch) adhesives are necessary to bond high performance and recycled papers. Variation in the amount of  starch or water changes the solids content of the adhesive. Analyzers for moisture or solids measurement are available to corrugators. It is critical that the analyzers be calibrated against strict standards. Generally, Generally, adhesive samples are analyzed by outside laboratories using either oven, infrared or microwave technologies. To determine whether excessive water is entering an adhesive system, samples of fresh and stored adhesive are analyzed for water content and compared. If the solids levels are equal, then no excess water has entered the system. If water has entered the system, the solids level in stored adhesive will be lower lo wer..

17

 

CORRUGATED MAKES IT HAPPEN FOR

18

MANUFACTURING

 

Board Testing Traditionally, moisture is determined with a forced air or vacuum oven, but other devices that incorporate infrared

Ply Separation T-812

or microwave technologies have shown to be just as accurate and are faster.

Ply separation the water resistancyinofwater finished board.determines Board samples are submerged for 24 hours, removed and drained of excess water. The linerboard facing is gently pulled apart from the medium. If there is resistance and fiber tear, the board is considered water-resistant.

There are many tests for determining the quality of  combined board. Below are some of the more frequent tests. Many of these standard tests have achieved a TAPPI designation, which is noted next to the test name. Specific test procedures may be obtained obt ained by contacting TAPPI.

Glue Pattern (unofficial) Caliper T-411 Caliper, or thickness Caliper, thickness,, is generally the first test performed on finished board. At plant sites it is usually conducted using a micrometer and is considered a diagnostic test to monitor the operation of the corrugator.

Edge Crush Test (ECT) T-811 Corrugators use this test to determine the edgewise compressive strength of their board. This test considers the role of the medium in overall strength. A compression machine is necessary. The ECT of a combined board is dependentt on the paper combination used. dependen

Dry Pin Adhesion T-821 This test measures the force necessary to separate corrugated board between the flute tips of the medium and its linerboard facings. A special pin adhesion attachment and compression machine is necessary.

For diagnostic purposes, it is often useful to soak a sample of corrugated board in water to separate the linerboard from the medium. Then, simply spray the inside surface of the liner with a dilute solution of 0.1 percent iodine-potassium iodide. iodide. The iodine solution will stain the glue line, or starch, blue. From the pattern it may be possible to determine how the adhesive was applied or whether it was applied correctly.

Top to Bottom Compression T-804 This test is used to measure the ability of a corrugated or solid fiber shipping container to resist external compressive forces. A completed, but empty empty,, box is placed in a compression tester and an external force is applied until the box fails.

Basis Weight Combined Board T-410 Basis weight is a physical measurement. measurement. A sample of measured board is weighed on a balance and expressed in pounds per MSF.

Wet Pin Adhesion (unofficial) Wet pin adhesion is a variation of the dry pin test. It tests the water resistance or waterproof characteristics of  the finished board. In the wet pin test, the board can be submerged in water as long as 24 hours, removed and drained of excess water. The pin adhesion test is then conducted on the wet board. bo ard. Wet pin results are much lower than dry pin results. A range from about two to seven lbs. per linear foot indicates water-resistant water-resistant board. Wet pin results of between 10–12 lbs. per linear foot indicate waterproof board to most corrugators. co rrugators.

19

 

CORRUGATED MAKES IT HAPPEN FOR

20

DISTRIBUTION

 

Quality Monitoring and Control at the Adhesive Station The fitness of the adhesive is related directly to t o the quality of the bond that will be produced at the corrugator. Therefore, Therefor e, it is critical to maintain control of several key characteristics of the adhesive. Adhesive temperature, viscosity and gelatinization temperatures are the critical  points to monitor and control in order to maintain consistent adhesive. Many problems can be avoided and eliminated through the regular use of statistical process control  (SPC). Development of a data collection col lection program is recommended recommend ed to achieve meaningful statistical control of the process. The starch supplier can be a valuable resource. Many suppliers offer SPC consultation or even training. Another resource for SPC training is the American Society for Quality Control (ASQC). Generally, the SPC or Quality Control Coordinator in the Generally, plant will work closely with the starch supplier to set up control and monitoring systems and determine consistent, meaningful measurement measurement points in the system.

Statistical Process Control  The first step in monitoring any of the three control  points (viscosity, adhesive temperature, gelatinization point) is to gather enough data to determine the process capability.. See Figure 9 for a typical example of a chart capability used to gather data. If the process is determined not to be capable in any area, the starch supplier should be called upon to provide assistance. The process should be corrected and additional  data gathered to verify the improvements and determine if the process is capable. The goal is to keep the starch adhesive process in tight control. Once the process is determined capable, then additional data should be collected and the mean (X), upper control limits (UCL) and lower control limits (LCL) should be calculated. The mean (X) should closely match the desired target. If the mean is not numerically close to the target, then the process must be corrected. These process corrections can be as simple as an adhesive formula change, an equipment repair or calibration. Once again, starch suppliers should be consider considered ed a resource for these process corrections.

21

 

FIGURE 9

INDIVIDUAL AND MOVING RANGE (X & MR) CHART 

CHARACTERISTICS

UNIT OF MEASURE

Starch Kitchen

Adhesive Viscosity

Seconds (Stein Hall)

DATE

2-2 2-3 2-3 2-4 2-4 2-5 2-5 2-5 2-6 2-6 2-6 2-6 2-10 2-10 2-10 2-11 2-11 2-12 2-12 2-12 2-13 2-13 2-13 2-17 2-17

TIME

2:15 8:00 :00 12:30 9:00 :00 12:00 9:00 :00 12:00 2:30 2:30 7:12 10:30 1:00 2:45 :45 7:45 :45 9:00 :00 11:30 8:30 10:15 6:30 :30 10:30 1:30 8:30 11:30 1:45 1:45 7:00 7:00 9:25

OPER. INITIALS

 JS

MEASUREMENT 

41

42

42

47

45

39

34

43

35

41

44

31

42

43

32

37

41

37

41

43

44

35

36

32

42

41 1

42 0

42 5

47 -2

45 -6

39 -5

34 9

43 -8

35 6

41 3

44 -1 -13

31 11

42 1

43 -1 -11

32 5

37 4

41 -4

37 4

41 2

43 1

44 -9

35 1

36 -4

32 1 10 0

1

2

3

4

5

6

7

8

9

10

11

1 12 2

13

14

15

16

17

18

19

20

21

22

2 23 3

24

25

1

2

3

4

5

6

7

8

9

10

11

1 12 2

13

14

15

16

17

18

19

20

21

22

2 23 3

24

25

PREVIOUS MOVING RANGE

50    S    T    N    E    M    E    R    U    S    A    E    X    M    L    A    U    D    I    V    I    D    N    I

45 40 35 30 25

15 10    S    E    G    N    A    R    R    G    M    N    I    V    O    M

5 0 -5 -10 -15

NOTES:

22

 

Troubleshooting Common Corrugating Problems DIAGNOSING VISCOS VISCOSITY ITY PROBLEMS - System: System: Primary/Secon Primary/Secondary dary Mixing Systems, Single Tank Mixing Systems, High Shear Mixing Systems Adhesive viscosity is a critical parameter for quality corrugated b oard. It is a relatively easy variable to control when the underlying cause of a problem is understood. Problem:

Common Causes:

Low viscosity at the mixer

Not enough starch in the cooked portion of the formula   •Scale out of calibration Too much water in the cooked portion of the formula   •Water leak   •Water meter out of calibration   •Improper measuring device   •Condensate from steam lines   •Condensate from steam leak   •Unwanted wash water going into the mixer Too much water in the secondary addition or secondary mixer   •Water leak   •Water meter not calibrated   •Improper measuring device •Condensate from from steam steam leak lines    •Condensate Cooked portion too hot (+160˚F [71.1˚C])   •Steam leak   •Temperature controller out of calibration   •Temperature gauge out of calibration (reading too low) Finished batch too hot   •Cooked portion too hot   •Temperature controller out of calibration   •Cooling water too warm (seasonal)   •Mixer shaft overheating due to bad bearings   •Improper balance between the cooked portion and cooling water Too much shearing of the cooked portion of the adhesive   •Cooked portion mixed too long   •Drop time too slow or slow pump over time   •Too long a time on high shear Finished batch being mixed too long Substituting incorrect borax (5 mol vs. 10 mol vs. boric acid)

High viscosity at the mixer

Too much starch in the cooked portion of the formula   •Scale out of calibration Too much starch in the secondary mixer   •Scale out of calibration Not enough water in the cooked portion of the formula   •Water meter out of calibration   •Improper measuring device Not enough water in the secondary addition or secondary mixer   •Water meter out of calibration   •Improper measuring device Cooked portion too cold   •Temperaturee controller out of calibration •Temperatur   •Temperaturee gauge out of calibration •Temperatur   •Cooling water too cold (seasonal) Finished batch too cold (optimum temperature 100 to 102˚F [37.8 to 38.9˚C])   •Cooked portion too cold   •Temperaturee controller out of calibration •Temperatur   •Temperaturee gauge out of calibration •Temperatur   •Cooling water too cold (seasonal)   •Bulk starch too cold (seasonal)   •Improper balance between the cooked portion and cooling water Not enough shearing of the cooked portion of the adhesive   •Cooked portion not mixed long enough   •Too fast a drop or fast pump over time   •System not left on high shear long enough Finished batch not being mixed long enough Incorrect amount of borax Substituting incorrect borax (5 mol vs. 10 mol vs. boric acid)

23

 

DIAGNOSING VISCOSITY PROBLEMS - Problems Common To All Systems Adhesive viscosity is a critical parameter for quality corrugated board. It is a relatively easy variable to control when the underlying cause of a problem is understood. Problem:

Common Causes:

Low viscosity at the storage tanks

Low viscosity adhesive coming from mixer   •Finished batch temperature too high   •Temperature of cooked portion too high   •Bad temperature controller   •Insufficient amount of cooked starch in primary portion   •Bulk scales out of calibration Temperature of the adhesive too high   •Temperature •Temper ature viscosity control (TVC) system set too high   •TVC controller out of calibration   •Adhesive returnin returning g from machine at an elevated temperature   •Finished batch temperature too high   •Bad bearings on the agitator causing the shaft to overheat   •Bad bearings on the supply/return pump Storage tank agitators running continuously   •Agitator timers not operating properly   •TVC system controller malfunctio malfunctioning ning   •Poor heat transfer from TVC coils   •TVC water too hot   •TVC coils coated with gelled adhesive   •TVC water too cold   •TVC circulation pumps not operating Unwanted water in adhesive   •Wash water coming back from corrugator   •TVC coil leaking inside storage tank Over-shearing of the adhesive   •High rpm supply and return pumps   •Too many elbows in the supply and return lines   •Supply and return line pipe diameter too small    •Pipe size reductions in supply and return lines   •Partially •Partial ly open valves in supply and return lines   •Air pressure too high on air diaphragm pumps Old adhesive (stored too long) Adhesive treated with resin (WPA) mixed with domestic adhesive Low solids adhesive formula Microbiological contamination of adhesive

Hig Hi gh vis visco cosi sity ty at th thee sto storrag agee tan tanks ks

24

High vis Hig visco cosi sity ty ad adh hes esiv ivee com comin ing g fr from th the mi mixer Adhesive viscosity "growing" in storage   •Too much caustic in the formula   •Scale out of calibration   •Caustic meter out of calibration   •Not enough borax in the formula   •Scale out of calibration   •Borax timer set improperly   •Wrong type of borax (5 mol vs. 10 mol) Adhesive cold   •TVC system not operating properly   •Loss of steam pressure in the plant   •Finished batch temperature should be 100 to 105˚F  Storage tank agitators not operating properly Alkali-sensitive starch

 

DIAGNOSING VISCOSITY PROBLEMS - Problems Common to All Systems Adhesive viscosity is a critical parameter for quality corrugated board. It is a relatively easy variable to control when the underlying cause of a problem is understood. Problem: Low viscosity at the machine

Common Causes: Excessive adhesive temperature in the starch pan (between 110-120˚ 110-120˚F) F) Incorrect storage tank temperature Incorrect TVC water temperature Starch feed and return line exposed to steam lines   •Insulate these lines for better temperature control  Starch feed line running over top of single facer Increase starch flow through the pan   •Adhesive temperature increases the longer it remains in the pan   •Higher temperatures lower the viscosity Water dripping into the starch pan   •Condensate •Conden sate from steam showers Partially open valves in the starch feed and return lines   •Flow restriction will create shear causing a drop in viscosity Air pumps feeding or returning adhesive running at high PSI levels Bad Viking pump (weak suction) creates too much shear Pumps not sized properly for the corrugator Plant has doser   •Recirculating •Recirculatin g the adhesive causing a drop in viscosity Low viscosity adhesive coming from the storage tanks

High viscosity at the machine

Low adhesive temperature •Cold weather outside causing the temperature drop Very high temperature temperature in the starch pan (in excess of 120˚F [48.9˚C]) Pressurized machine running high solids over 30%   •Excess heat inside the chamber causing water loss Chemicals in formula are out of ratio (borax to caustic) Steam leak directly into the pan Steam leak blowing into a starch line Poor agitation or no agitation of the adhesive held in storage High viscosity adhesive coming from the storage tanks

Viscosity decrease after overnight or weekend storage

Clean-up water returned to storage tanks Agitators/circulating Agitators/cir culating pumps left running Circulating lines full of water TVC system not working properly Water leak from the TVC coil  Temperature of the adhesive too high Insufficient amount of cooked starch in the formula to hold viscosity properly Primary portion of the formula is overcooked Bacteria

25

 

DIAGNOSING TYPICAL GEL TEMPERATURE PROBLEMS Problem:

Common Causes:

Gelatinization temperature too high

Not enough caustic in the adhesive   •Scale out of calibration   •Caustic meter set too low   •Caustic meter out of calibration Too much borax in the adhesive   •Scale out of calibration   •Borax timer not working properly Too much starch in the adhesive   •Scale out of calibration Too much water in the adhesive   •Water meter out of calibration   •Mixer scale out of calibration Substituted incorrect borax formula (5 mol vs. 10 mol vs. boric acid) Borax too old (dry (dry,, becomes more concentrated) Caustic soda beads too old Liquid caustic too old Caustic stratified in storage tank sending low concentrations of caustic Wrong concentration of liquid caustic (See Appendix D) Adhesive stored too long Addition of resin into adhesive Wrong or defective thermometer used by starch person   •Do not use an electronic or dial thermometer Test is performed improperly or by different people

Gela Ge lati tini niza zati tion on te temp mper erat atur uree to too o lo low w

Too mu much ch ca caus usti ticc in th thee ad adhe hesi sive ve   •Scale out of calibration   •Caustic meter set too low   •Caustic meter out of calibration Not enough borax in the adhesive •Scale out of calibration   •Borax timer not working properly   •Borax discharge tube plugged Not enough starch in the formula   •Scale out of calibration Substituted incorrect borax in the formula (5 mol vs. 10 mol vs. boric acid) Problem with caustic soda   •Liquid caustic too cold   •Liquid caustic crystallized in storage tanks sending high concentrations of caustic   •Wrong concentration of liquid caustic (See Appendix D)

26

 

DIAGNOSING CORRUGATING EQUIPMENT AND BOARD QUALITY PROBLEMS Board quality begins at the single facer. To insure that good quality board is being produced at high speeds, it is critical to maintain the single facer in good mechanical condition. Problem:

Common Causes:

Soft Board: This causes poor pin adhesion, low top-to-bottom compression

Excessive adhesive application Operator error   •Low machine temperature

and poor print quality

Over conditioning of the medium Wet paper - medium or liners Excessive rider roll pressure at double backer glue machine, crushing flute tips Uneven roller pressure in hot places or cooling section of double backer Board cut off knife pressure too high Low viscosity of the adhesive Low solids of the adhesive Water sprays being used to help control warp Hot plates not level  Incorrect roller pressure in the cut off section or stacking section of the machine

Washboard Appearance: This problem usually occurs once the board has cured and causes a poor printing surface and brittle edges during conversion

Heavy adhesive application at single facer or double backer Adhesive viscosity too low Adhesive solids too low Wet paper (roll stock stored outside) Excessive heat applied to lightweight liners Glue roll set to wrong paper speed Over-dried liners

Dry Board, Zipper Board: Creates waste, low pin adhesion and poor top-to-bottom compression

Adhesive application at single facer or double backer too light Water penetrates medium too quickly   •Low viscosity adhesive   •Medium with fast water drop Low solids adhesive Too much borax in the formula Glue roll in double backer at wrong speed (paper comes apart easily in one direction, but has good fiber pull in the other direction) Too much heat application at single facer or double backer Slow machine speed Adhesive gel temperature too low Poorly formed flutes (highs and lows) Slipping of the board coming through the machine

Leaning Corrugation: This causes low board caliper, poor pin adhesion, poor topto-bottom compression, poor printing surface

Misalignment of corrugator rolls Excessive wear on corrugator rolls Pressure between corrugator rolls too low Top and bottom belts traveling at different speeds Excessive rider roll pressure at double backer glue station Adhesive application at single facer or double backer Drag through hot plate

Slipping Board - General 

Excessive tension on double facer Loose or worn belts Belt rollers lift Top and bottom belts traveling at different speeds Treatment or finish of bottom liner causing excessive drag on the hot plates

Slipping Board: This problem is produced by a surface bond only and delaminates after curing

Excessive drag on single face web Loose or worn corrugator belts in double facer Hot plate rollers are up Rollers in pulling section of the double facer are up Corrugator belts traveling at different speeds Coating on bottom liner creating drag

27

 

DIAGNOSING CORRUGATING EQUIPMENT AND BOARD QUALITY PROBLEMS Board quality begins at the single facer. To insure that good quality board is being produced at high speeds, it is critical to maintain the single facer in good mechanical condition. Problem:

Common Causes:

Dry Streak: Poor bonding, low top-to-bottom compression of finished carton

Dirty fingers on the single facer Worn fingers - flat spot on tip Finger running too close to lower roll  Too much vacuum pressure pressure on a vacuum style single facer Dirty cleanout prongs Water jacket malfunctioning High adhesive viscosity Poor lateral adjustment of corrugating roll  Tension on medium too high

"Cracker" Board: This problem is identified by a cracking sound when flexed

Slippage between single facer web and double backer line Light glue application Glue solids too low Excessive unglued or high-low corrugations Excessive borax in formula Liners too hot Medium too dry Too much drag on medium Slow machine speed Low gel temperature Glue roll and paper machine speeds synchronized Poorly formed flutes

Light Glue Pattern at Double Backer: Brittle or zipper board appearance

Low glue roll setting Rider roll set too high Glue roll speed too fast Smooth glue roll  Dirty or worn glue roll  Low viscosity adhesive Too much drag on single facer web

Light Glue Pattern at Single Facer: Delaminates, poor bonding

Glue roll too far from corrugating roll  Smooth glue roll—not transferring enough adhesive Glue roll settings too low Dirty or worn glue roll  Improper pressure roll setting Poorly formed flutes (highs and lows)

Foaming of Adhesive in Pans: Poor bonding and high starch consumption

Air in starch lines   •Leak in pumps Wiper blade improperly installed or dirty wiper blade on metering roll  Flexo waste water used for adhesive make-up Resin in the adhesive Adhesive viscosity too low Not using antifoam with adhesive made with High Shear system High corrugating speeds

Adhesive Between Flutes: This problem creates warp problems, high starch consumption, poor bonding and overall poor quality

28

Starch setting too high Low viscosity adhesive Low solids adhesive Improper adhesive formula Rider roll set too low at double backer Improper glue roll speed Bad wiper blade on metering roll  Skip clutch not holding glue roll  Bad glue on metering roll  Adhesive blown off the flute tips when running a jet assist for heavy-weight board Long “tack” adhesive

 

DIAGNOSING CORRUGATING EQUIPMENT AND BOARD QUALITY PROBLEMS Board quality begins at the single facer. To insure that good quality board is being produced at high speeds, it is critical to maintain the single facer in good mechanical condition. Problem:

Common Causes:

White Glue Line: Delaminates after curing, low pin adhesion, poor top-to-bottom compression

Insufficient gelatinization Gel temperature too high Incorrect temperature at pressure roll, corrugator rolls or hot plates   •Low boiler pressure Low viscosity Wet paper   •Roll stock stored outside

Spotty Glue Application on the Single Face Side: Poor bonding, low pin adhesion, low top-to-bottom compression

Glue roll motor problem Finger set too low Worn finger Medium not properly conditioned Medium not forming properly Medium sticking to corrugator roll  Excessive drag on medium Water dripping on medium Dirty corrugator rolls High/low calibrated medium Bad glue roll/metering roll 

Adhesive Sets Up on Fingers: High starch consumption, poor bonding, low pin adhesion, poor top-to-bottom compression, low production speeds

Gel temperature of adhesive too low Adhesive viscosity too high Temperaturee in glue pan too high Temperatur Improperly conditioned medium Paper temperature too high Fingers worn Cleanout fingers too loose or tight against glue roll  Incorrectly set taper speed Water jacket not functioning properly Poor flow of the adhesive through the starch pan

Loose Edge on the Single Face Side: Poor quality board, high waste, low production speeds

Wet paper roll Adhesive improperly applied to medium Not enough brake on medium Fingers improperly adjusted Dirty corrugating rolls Lack of pressure on roll  Wet liner edge Medium wider than liner Improperly set slitter knife Roll stand out of parallel  Wrap arms on the medium or liner out of parallel  Large difference in paper temperature from one side of the machine to the other side  Starch dam out of adjustment at single facer

Loose Edge on the Double Back Side: High waste, low production speeds, poor print quality

Sheet guide compressing flutes Wet streak on liner edge Worn corrugator belt Worn rollers in hot plates Wet paper roll  Dirty hot plates Low adhesive solids Too much heat Improperly set slitter knife Low viscosity Roll stand out of parallel  Wrap arms on the medium or liner o ut of parallel  Bridge guides too tight Large difference in paper temperature from one side of the machine to the other side Not enough flutes in contact with glue roll  Starch dams out of adjustment

29

 

DIAGNOSING CORRUGATING CORRUGATING EQUIPMENT AND BOARD QUALITY PROBLEMS Board quality begins at the single facer. To insure that good quality board is being produced at high speeds, it is critical to maintain the single facer in good mechanical condition. Problem:

Common Causes:

Highs and Lows - Flutes Not Glued - Single Face Side/  Double Back Side

Fingers set too low Pressure between corrugating rolls too low Dirty rolls Corrugating medium too wet Glue roll angled improperly Too much drag on the single face web at the double back glue line Excess drag on medium Low caliper medium Medium surface temperature too high Improper brake pressure on medium

Problem:

Common Causes (All Machines):

High and Low Corrugation: Low pin adhesion, poor topto-bottom compression, poor print surface, overall  poor quality

Medium improperly conditioned   •Lack of steam   •Proper steam (wet) Surface temperature of medium too high Improper pressure on corrugating rolls   •Worn or old rolls Glue roll out of parallel  Roll stand out of parallel  Rider roll out of parallel at double backer glue station Improper rollers hot plates Improper pressure brake on on single faceinweb Excess drag on medium Low caliper medium Common Causes (Finger Machines): Fingers improperly improperly adjusted, worn, old or dirty Common Causes (Vacuum Machines): Low vacuum settings   •Bad seals Plugged holes/slots in corrugated roll  Common Causes (Pressure Machines): Improper pressure   •Leaky cabinet seals Plugged holes/slots in corrugating roll 

Blisters: Poor quality, poor print surface, low pin adhesion, poor top-to-botto top-to-bottom m compression

30

Fingers worn, old, dirty Fingers adjusted improperly Incorrect heat in corrugator rolls, pressure rolls, hot plate se ction Poor quality paper Wet paper Medium not properly conditioned Low viscosity adhesive Liner too hot Medium too hot Medium or liner out of calibration Wet streaks in the medium or liner Dirty or worn glue roll  Improper brake pressure on single face liner Worn corrugator rolls

 

DIAGNOSING WARP PROBLEMS Warp is generally caused by moisture or tension imbalance. Problem:

Common Causes / Corrective Actions:

Norm No rmal al War arp p (Si (Side de-t -too-Si Side de Up Wa Warp rp))

Caused Caus ed by mo mois istu ture re in th thee sin singl glee fac facer er li line nerr   •Add more heat (increasing warp) to the single face web   at the double backer glue machine

Operating the moisture content ofFootnote: the singleIffacer liner roll is greater than 2 percent over that of the double backer liner roll, then the roll should be changed. Preheaters on the machine can only remove 1 to 2 percent moisture from roll stock. Should the moisture imbalance be greater than 2 percent, warp will occur.

Reverse Warp (Down Warp) Operating Footnote: If the moisture content of the double back roll is greater that 2 percent over the single-face liner roll, then the roll should be changed. A difference of 2 percent or more in moisture between the single-face liner and the double back liner will create warp.

                  

•Reduce heat (decreasing warp)glue to the double facer liner at the double backer machine •Increase single facer liner warp on the 36-inch preheater at the single facer •Increase the warp on the medium preconditioner •Decrease steam shower into the medium •Reduce the amount of single face web on the bridge •Increase machine speed •Reduce the amount of adhesive used at the single facer •Increase the amount of adhesive used at the double backer •Lift some ballast rolls in the hot plates

Caused by moisture in the double facer liner   •Increase heat to the double facer liner (increase wrap on the 36-inch preheater)   •Decrease the heat in the single facer web at the double backer glue machine (decrease the wrap on the 36-inch preheater)   •Increase the steam shower on the medium   •Lower all rollers in the hot plate section •Check steam pressure in the hot plates and increase if possible   •Increase the amount of single face web on the bridge   •Reduce the speed of the machine   •Reduce the amount of adhesive at the glue machine   •Increase the amount of adhesive at the single facer   •Add small amount of moisture to the top corrugator belt (use steam spray across the entire belt)   •Use water spray on single face web

Operating F  ootnote: If th e moisture content o off the double back roll is greater that 2percen t over the single face liner roll,then roll,then the r oll should be changed. A difference of 2per cent or more in moisture between the single face liner and the double back liner will create warp.

 

31

 

DIAGNOSING WARP PROBLEMS Warp is generally caused by moisture or tension imbalance. Problem:

Common Causes / Corrective Actions:

S Warp (combination of  normal and reverse warp): This warp is usually caused

Wet streak in roll liner or medium Thin streak or edge in roll of liner will warp in opposite direction to wet streak Loose edge in roll of liner does not hug preheater

by variations in moisture (wet streaks) across the web in a roll of liner or medium, or by machine conditions which apply variable amounts of  heat or adhesive across the web

Wet edge in or liner to outside storage Out of level outdue of square machine condition preventing liner from contracting preheater firmly across the web Single face glue roll or doctor roll (glue roll and transfer roll) out of parallel  Improper crown between single face glue roll and doctor roll loose, worn or dirty in some areas Scraper blade on single face or double back doctor roll loose, worn or dirty in some areas Single face glue or doctor roll (glue roll and transfer roll) galled   in some areas or pitted on ends Double backer rider roll out of parallel  Double back glue roll and doctor roll out of parallel  Applicator roll out of parallel to the corrugating roll  Hydraulic lift of the glue mechanism not functioning correctly at the single facer; partially blocked steam shower Distorted steam chests ca using uneven board temperatures across the machine  Possible roll stand out of parallel 

Operating Footnote: If the machine is equipped with a water spray, this is usually the best way of controlling the S warp. The water spray should be used on the single face side of the web only.

Machine Direction Warp (End-To-End Warp):

Tension greater in one liner than in the other

The end-to-end warp can be either up or down, but is always in the machine direction End-To-End Warp

Tension greater on the single face liner than on the double back liner Single face liner is pulling back on the sheet "Drag" on the top liner, usually from a drag belt on the bridge Preheater locked down not turning, adding tension to the single face web going into the double facer Running with too much brake on the single face liner at the single facer Running with too much paper on the bridge Running with too much brake on the medium pulling back on the single face web Incorrect tension on web; increase tension

End-To-End "Down" Warp

Tension greater on the double back liner than on the single face liner "Drag" on the bottom liner usually caused by a bad break on the roll stand; preheater locked down not turning, adding tension to the bottom liner Dirty hot plates adding drag Need to lubricate double face liner, especially when running coated liners

Operating Footnote: The corrugator crew may find the only way to control this type of warp will be with machine speed. The higher the speed, the less drag they see, because at higher machine speed they can operate with less brake.

Cross Machine Direction (CD) Side-To-Side Warp: This is a warp that usually is found within a few hours after the board is run. The problem is moisture and tension along with the temperature in the working area

Operating Footnote: The corrugator crews should have a good understan understanding ding of the adhesive system within their machine and also understand the proper use of water sprays. Using the adhesive and water sprays properly is the best way to control this type of warp.

32

Wrap arm or roller out of parallel giving uneven contact pressure pressure in the double facer Out of round glue roll at the single facer, applying adhesive light and heavy Machine speed from time to time will cause the adhesive to be applied heavy and light Rollstock with wet streaks or moisture content higher than normal 

 

DIAGNOSING WARP PROBLEMS Warp is generally caused by moisture or tension imbalance. Problem:

Common Causes / Corrective Actions:

Twist Warp (Combination of  End-to-End and Side-to-Side Warp): Twist warp is caused by uneven tension or stress across the web of any or all  components during the combining process

Roll stand out of level  Preheater out of level  Splice roll out of level 

Operating Footnote: Twist warp is seen more often on machines that run a two piece top corrugator belt. One belt will be running faster than the other adding stress to the web. If the twist warp occurs off the machine, a wet streak will be noticed in one of the liners.

Post Warp (warp observed several hours or days later): The degree of this type of warp will depend greatly on the way the sheets were stacked and the location of  the stack. About the surest way to minimize in-storage warping has proved to be producing as dry as possible board on the corrugator, using as little adhesive as possible, and using preheaters to their fullest capacity

Roll stand, out of square to the machine Dirt on wrappreheater roll or preheater Bridge web guide out of level, out of square or off center Crown breaker roll in double back glue machine out of level  Double back glue machine rider roll out of level  Top double back belt pulls unevenly across web Loose or tight edge in roll of liner Uneven or diagonal stresses in roll liner

Check liners for wet streaks Reduce web tension on the single face side Reduce break drag on all roll stands Preheaters should be free turning Hot plate section should be clean and free of dirt build up Adhesive formula should have the proper solids for the mix within the plant If the machine uses a two piece belt, check the speed of the belts Sheets must be stacked properly Board coming off the machine should be dry and firm Should have proper storage area for the finished sheets

Operating Footnote: When sheets warp after they leave the corrugator, moisture is most likely the problem. The sheets coming off the machine will be wet or damp to the touch. Storing finished sheets near open doors and windows, or loading the sheets into a cold truck before they have properly cured, will cause warp.

33

 

Appendix A

Equivalent Amounts of Borax for Starch Formulations

English Units, lb 10 Mol  (decahydrate)

5 Mol  (pentahydrate)

Boric Acid

10 Mol  (decahydrate)

5 Mol  (pentahydrate)

Boric Acid

20 21 22

15.50 16.00 16.75

12.33 13.00 13.50

9.0 9.5 10.0

7.0 7.2 7.6

5.5 5.9 6.2

23

17.50

14.25

10.5

8.0

6.5

24 25

18.25 19.00

14.75 15.50

11.0 11.5

8.4 8.8

6.8 7.1

26 27

19.75 20.50

16.00 16.67

12.0 . 12.5

9.2 9.6

7.4 7.7

28

21.25

17.25

13.0

9.9

8.0

29

22.00

18.00

13.5

10.3

8.3

30 31

23.00 23.75

18.50 19.00

14.0 14.5

10.7 11.1

8.6 8.9

32

24.50

19.75

15.0

11.5

9.2

33

25.25

20.25

15.5

11.8

9.6

34

26.00

21.00

16.0

12.2

9.9

35

26.75

21.50

16.5

12.6

10.2

Table courtesy of TAPPI

34

Metric Units, kg

 

Appendix B

Microbiological Growth/Control in Corrugating Adhesives For 666 Gallon Primary – Secondary Units

Step 2 — Mixer 

Step 1 — Primary mixer 

Fill mixer with 350 gallons of water (DO NOT HEAT). HEAT). Add 6 quarts of commercial household bleach and agitate for 15 minutes. Pump the solution into the storage st orage tank and through the circulation lines for an additional 15 minutes. Dispose of the solution in an appropriate manner. manner.

Fill mixer with 150 gallons of water and heat to 130˚F  [54.4˚C]. Add 15 pounds of a commercially available industrial strength strength cleaner and agitate for 30 minutes. DO NOT discard the solution. Proceed to Step 2. Step 2 — Secondary mixer 

Fill mixer with 300 gallons of water and heat to 130˚F  [54.4˚C]. Add 30 pounds of a commercially available industrial strength strength cleaner and agitate for 30 minutes. Add the solution in the primary mixer into the secondary mixer. Pump the mixer. t he combined solutions into the storage tank and through the circulation lines for 30 minutes. Dispose of solution in an appropriate manner. manner. Step 3 — Primary mixer 

Fill mixer with 150 gallons of water (DO NOT HEAT). HEAT). Add 2 quarts of commercial household bleach and agitate for 15 minutes. DO NOT discard the solution. Proceed to Step 4. Step 4 – Secondary mixer 

Fill mixer with 300 gallons of water (DO NOT HEAT). HEAT). Add 1 gallon of commercial household bleach and agitate for 15 minutes. Add the solution in the primary mixer into the secondary mixer. Pump the combined solutions into the storage tank and through the circulation lines for an additional 15 minutes. Dispose of the solution in an appropriate manner. Step 5 — Flush all mixers, tanks and lines thoroughly with clean water to remove all trace amounts of chemicals.

For 666 Gallon No-Carrier & Single Tank Mix Systems

Step 3 — Flush all mixers, tanks and lines thoroughly with clean water to remove all trace amounts of chemicals.

For 300 Gallon High Shear Systems Step 1 — High shear mixer 

Fill mixer with 300 gallons of water and heat to 130˚F  [54.4˚C]. Add 39 pounds of a commercially available industrial strength cleaner and agitate for a full 15 minutes with the high shear ON. Pump solution into the storage tank and through the circulation lines for 30 minutes. Dispose of the solution in an appropriate manner. manner. Step 2 — High shear mixer 

Fill mixer with 300 gallons of water ( DO NOT HEAT). Add 5 quarts of commercial household bleach and agitate for 10 minutes. Pump the solution into the storage st orage tank and through the circulation lines for an additional 15 minutes. Dispose of the solution in an appropriate manner. manner. Step 3 — Flush all mixers, tanks and lines thoroughly with clean water to remove all trace amounts of chemicals.

Note for all systems: Growth can occur in an empty section of pipe or on the underside of tank covers. Using proper discretion, the solutions can also be used to clean the starch pans at the machine.

Step 1 — Mixer 

Fill mixer with 350 gallons of water and heat to 130˚F  [54.4˚C]. Add 45 pounds of a commercially available industrial strength cleaner and agitate for 30 minutes. minutes. Pump the solution to the storage tank and through the circulation lines for 30 minutes. Dispose of the t he solution in an appropriate manner.

35

 

Appendix C

Testing The Gelatinization Temperatures Introduction

Procedure

With a few pieces of simple equipment and a little practice, the gel temperature of a starch adhesive can be measured quickly, accurately and reproducibly.

1. Fill a container container (beaker) with water to within within 1/2 inch inch of the top, place on a hot plate and heat to between 170˚F and 180˚F [76.7˚C and 82.2˚C]. (DO NOT BOIL THE WATER.)

Equipment

2. While the water is heating, heating, pour the the starch adhesive adhesive to be tested into the test tube (fitted with a test tube holder or clamp) to a level of 1 to 2 inches, or approximately 1/3 of the tube t ube volume. Insert the thermometer as shown to the left.

a b c d e f  g

3. When the water has reached reached temperature, temperature, turn the hot plate OFF and place the tube in the hot water (as shown). Immediately begin stirring the adhesive with the thermometer, thermometer, being careful to wipe the side of the tube to prevent localized heating and gelling. 4. As the temperature rises, the adhesive adhesive will begin to thicken as the gel point is approached (usually between 139˚F and 152˚F [59.4˚C and 66.7˚C]). The temperature rise will pause (level off) for a few seconds at the actual gel value, then continue upward. RECORD the temperature in degrees, where the leveling occurred. (NOTE: If the water is too hot, the temperature pause will be shorter and often more difficult to detect.) 5. The test requires requires some skill; it is suggested that the the test be repeated and an average value reported.

Recommendations

a. Glass thermometer calibrated in degrees Fahrenheit (F) (See Recommendations Recommendations 1 & 2 on thermometers) b. Heat stable glass test tube tube c. Te Test st tube holder holder or or suitable suitable clamp clamp d. Heat stable glass beaker or other suitable container container e. Star Starch ch adhesiv adhesivee to be tested f. Hot water water at proper temperat temperature ure (see (see Procedure) Procedure) g. UL approved hot plate, plate, bottle warmer, warmer, etc.

36

1. Periodically, Periodically, check the accuracy of the thermometer thermometer by placing it in boiling water. It should read exactly 212˚F [100˚C]. 2. Glass thermometers thermometers are are recommended recommended over metal dial-type thermometers thermometers..

 

Appendix D

Specific Gravities and Concentrations of Caustic Soda Solutions Based on International Critical Tables

%NaOH

%Na2O

Sp. Gr. @ 60/60˚F  [15.6˚C]

Deg. Baumé @ 60/60˚F  [15.6˚C]

Lbs. NaOH Per Gal. @ 60˚F [15.6˚C]

Lbs. of Solution Per Gal. @ 60˚F [15.6˚C]

2

1.55

1.023

3.3

.17

8.53

4

3.10

1.045

6.2

.35

8.71

6

4.65

1.067

9.1

.53

8.90

8

6.20

1.089

11.9

.73

9.08

10

7.75

1.112

14.6

.93

9.27

12

9.30

1.134

17.1

1.13

9.45

14 16

10.85 12.40

1.156 1.178

19.6 21.9

1.35 1.57

9.64 9.82

18

13.95

1.201

24.3

1.80

10.01

20

15.50

1.223

26.4

2.04

10.20

22

17.05

1.245

28.5

2.28

10.38

24

18.60

1.267

30.6

2.53

10.56

26

20.15

1.289

32.5

2.79

10.75

28

21.70

1.310

34.3

3.06

10.92

30

23.25

1.332

36.1

3.33

11.11

32

24.80

1.353

37.8

3.61

11.28

34

26.35

1.374

39.5

3.89

11.46

36

27.90

1.394

41.0

4.19

11.62

38

29.45

1.415

42.5

4.48

11.80

40

31.00

1.435

44.0

4.78

11.96

42

32.55

1.454

45.3

5.09

12.12

44

34.10

1.473

46.6

5.40

12.28

46

35.65

1.492

47.8

5.72

12.44

48

37.20

1.511

49.0

6.05

12.60

50

38.75

1.530

50.2

6.38

12.76

52

40.30

1.549

51.4

6.72

12.91

37

 

Appendix E

Alkali (Caustic) Sensitivity – Settling Method Field Test For Corrugators This test has been designed for testing unmodified corn starch at the the corrugator’s site. For best results, the components should be weighed weighed.. Empirical information can be obtained if the containers are calibrated and marked with the component weights. The largest variable is the length of time the starch is in contact with the caustic solution prior to mixing. That time must be kept to a minimum to get a valid reading. It is easy to get a false negative result.

1. Weigh 145 g of test solution into into one 250 ml bottle. 2. Weigh 50 g starch into into another 250 ml bottle. If starch is being added to a marked bottle, it should be tamped to get proper amount. 3. Quickly pour starch into into bottle with test solution. 4. Quickly cap the bottle and shake for for 3 to 5 minutes. It is important that steps 3 and 4 be done quickly.

Equipment

5. Pour the starch slurry without without delay into the graduated graduated cylinder up to the 100 ml mark and put a piece of aluminum foil over the top as a cap.

• ml bottles ml bott les with with capsers caps • 250 100 ml graduated gradu ated cylinders cylind

6. Let the graduated cylinder cylinder stand for 24 hours.

Test Solution

Observation

From dry caustic: 13.3 g caustic 8.1 g 10 mol borax 1434.0 g distilled water

Read the bottom of the clear water layer. The The reading should be less than 70 ml if the starch is not alkali (caustic) sensitive sensitive..

From 50 percent caustic:

26.6 g 50 percent caustic 8.1 g 10 mol borax 1421.0 g distilled water

38

Test Procedure

 

Appendix F 

Alkali Sensitivity, Viscometric: Unmodified Starch Principle

Calculation

Starch granules that are heat damaged and no longer exhibit birefringence birefringence in aqueous suspension tend to swell  more readily in aqueous alkali than intact granules. Measured incremental incremental viscosity in dilute alkali at room temperature is related to enhanced viscosity of corrugated board adhesive formulations formulations..

(Unless the viscometer reads cps directly) Alkali Sensitivity, Sensitivity, cps = Scale Reading x 0.2 (See note 3)

Scope This procedure was developed specifically for unmodified corn starch and may not be used with modified starches without further study.

Equipment • Beak Beaker: er: Griffen Griffen low form, form, 400 ml capacity capacity

Notes 1. Variati Variation on in the normality of the t he sodium hydroxide hydroxide solution and the moisture content of the sample can have a significant effect depending on the alkali sensitivity. As the alkali sensitivity increases, the effects of these variables increase. Decreasing Decreasing the sodium hydroxide hydroxide normality from 0.25 to 0.24 decreases the measured alkali sensitivity by about 1.7 cps at 14 cps and about 0.1 cps at 5 cps. Reducing the sample moisture content from 11.0 to 10.0 percent increases the measured value by 0.6 cps at 14 cps and 0.2 cps at 5 cps.

• Brookfiel Brookfield d Viscometer: Viscometer: Model Model LV equipped equipped with a laboratory stand and UL Adapter with spindle SPOO.

2. The addition is generally generally done done in 5 to 10 seconds to avoid gelatinization of the intact granules.

• Stirrer: Stainless steel steel 3-blade propeller propeller,, 5 cm diameter, on a 0.8 x 31.0 cm shaft

3. As an alternative alternative procedur procedure, e, 200 ml of 0.1875 N NaOH can be used in place of the combination of 50 ml water and 150 ml 0.250 N NaOH. However However,, this change will  eliminate the ability to adjust the formulation for variationss in sample moisture content. The 0.1875 variation N NaOH can be obtained obtained commercially as a special order. order.

• St Stop opwa watc tch h • We Weig ighin hing g Paper Paper

Reagents • 1 percent (w/v) aqueous aqueous sodium hydroxi hydroxide de (NaOH) (NaOH)

Procedure The test is run at room temperature (about 77˚F [25.0˚C]). Transfer 150 ml of 1 percent NaOH and 50 ml of distilled water to the 400 ml beaker beaker.. Position the stirrer in the beaker and mix the solution at 600 rpm. Weigh 100 g (see note 1) of starch on the weighing paper. Add the starch to the agitated alkaline solution as quickly as possible but avoid lumping (see note 2) and start timer. Transfer Transfer 16.0 ml  of slurry to the UL Adapter and measure viscosity at 30 rpm.

4. The equipment, reagents reagents and method are all available from: Shape Products 1127 57th Avenue Oakland, CA 94621 (800) 444-0015 www.shapeproductsonline.com

39

 

Glossary

Amylose Hybrid — A corn variety forming more linear

Recycle

starch molecules

— In corrugating this refers to the reuse of  paper products

Borax — A crystalline compound used to control starch

Pearl  — Unmodified starch

swelling and provide additional adhesive tack

Shear Double Backer — Second glue station of corrugator;

— Mechanical action of breaking down starch adhesive

single face web glued to liner to form finished board

Single Facer Carrier Starch — Primary portion of adhesive

— First glue station of corrugating machine; medium is fluted and bonded to liner

Caustic Soda — Alkaline substance that causes starch

Starch — Complex carbohydrate from corn, potato,

granules to swell; also called sodium hydroxide

or tapioca processing

Feed Gluten

Steepwater

— Co-product of processed corn

Gelatinization — Point at which adhesive begins to

rice

— Water in which corn has been soaked or “steeped” during the initial stages of the corn wet milling refining process

thicken and develops bonding properties

Viscosity — Term used to describe adhesive flowability Germ — Product of processed corn; usually further Waxy Maize

refined into corn oil 

— A corn variety producing predominantly branched,, chained starch molecules branched

Glue Roll — Component of corrugating machine; transfers starch to flutes at double backer or single facer

High Ring Crush — High performance paper having a ring crush value of 2 pounds for every pound of basis weight

Liners — The flat paperboard portion applied to the fluted medium by applying adhesive to each flute tip

po rtion between the liners, which Medium — Fluted portion when combined with the liners, makes corrugated board

Modified Starch or mechanically

40

— A starch modified modified chemically chemically

Wick

— Penetrate

 

41

 

Your global resource Corn Products International, Inc., with international operations spanning 16 countries and 34 plants, is one of the largest corn refiners in the world and the leading refiner in Latin America. Our entire organization is dedicated to one mission: to be your preferred resource in product quality and service dependability on a global basis.

Corporate Headquarters Corn Products U.S. 5 Wes Westbroo tbrookk Corporate Center Center Westche Wes tchester ster,, IL 60154 United States (800) 443-2746 www.cornproductsus.com

Toronto Casco, Inc. 401 The West Mall, 2nd Floor Etobi Eto bicok coke, e, Ont Ontari ario o M9C 5P7 Canada (416) 620-2300 (Tor (Toronto) onto) (514) 694-4700 (Montreal/Eastern (Montreal/Ea stern Canada) www.casco.ca

CPIngredientes, S.A. de C.V C.V.. Av. Mariano Otero #1249, Floor 9 Torre Atlantico Rinconad Rin conadaa del Basque Basque 44530 Guadalajara, Jalisco Mexico (33) 3884-9000 ext. 3520 www.cpimex.com

CUSTOMER SERVICE CENTER – (800) 443-2746

Corn Products U.S. is a business unit of Corn Products International, Inc. Casco Inc. and CPIngredientes are affiliates of Corn Products International, Inc.

021-CM-99 Printed in the USA June, 2006 Quantity: 2,500 ©2006, Corn Products International, Inc.