60 -6 Coatings Technology Handbook, Third Edition Within a given chemical group, increasing molecular weight results in a modest increase in tensile strength and modulus, increased solution viscosity, and a modest increase in solvent and chemical resistance. In general, even the lowest molecular weight grades of these reins are high enough in molecular weight to be well within the chain entanglement region of the E ′ spectrum such that physical properties do not change drastically as molecular weight increases. Molecular weight variations can be used effectively to control the rheology/viscosity of coatings formulations more than the properties of the final coating. 60.3.3 Solution Viscosity Solution viscosity is a function of chemical composition, molecular weight, and solvent composition. Within a given chemical class, solution viscosity in a given solvent will increase with molecular weight. The effect of solvent composition on solution viscosity is more complex and not within the scope of this discussion. Solvent systems are often chosen for a variety of reasons other than viscosity: drying rate, toxicity and other environmental concerns, utility with other resins needed in a formulation, etc. Usually TA BLE 60.3 Solubility of Butvar Resins a Solvent Butvar Solutions Agitated at Room Temperature for 24 h 5% Solid Solution 10% Solids Solution B–72, B–73, B–74 B–76, B–79, B–90, B–98 Acetic acid (glacial) S S S Aceton I S SW Butyl acetate I S PS n -Butyl alcohol S S S Butyl cellusolve S S S Cyclohexanone S S S Diacetone alcohol PS S S Diisobutyl ketone I SW I N , N –Dimethylacetamide S S S N , N –Dimethylformamide S S S Dimethyl sulfoxide S S S Ethyl acetate, 99% I S PS Ethyl acetate, 85% S S S Ethyl alcohol, 95%, or anhydrous S S S Ethylene dichloride SW S SW Ethylene glycol I I I Isophorone PS S S Isopropyl alcohol, 95%, or anhydrous S S S Isopropyl acetate I S I Methyl acetate I S PS Methyl alcohol S SW S Methyl ethyl ketone SW S PS Methylene chloride PS S S Methyl isobutyl ketone I S I Naphtha (light solvent) I SW I N –Methyl–2-pyrrolidone S S S Propylene dichloride SW S SW Te t r a c hlorethylene SW SW SW Te t r a h y d r o furan S S S To l u e n eIPSSW To luene/ethyl alcohol (95%) (60:40 by weight) S S S 1, 1, 1–Trichloroethane SW S SW Xylene I PS SW a Key: S, Completely soluble; PS, partially soluble; I, insoluble; SW, swells (hazy, turbid). Source: Butvar/Formvar Brochure, publication no. 6.70E, Monsanto Chemical Company, Plastics and Resins Division, St. Louis, MO. DK4036_book.fm Page 6 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Polyvinyl Acetal Resins 60 -7 by judicious experimentation, a compromise solvent system can be found that will give a reasonable mix of the required properties. 60.3.4 Plasticizers Plasticizers are often used to soften the films prepared from the polyvinyl acetals. Among the suggested plasticizers for polyvinyl butyral are butyl benzyl phthalate, 2-ethylhexyl diphenyl phosphate, dihexyl adipate, and a verity of other phosphate, phthalate, adipate, sebacate, and ricinoleate esters. Rosin-based polyester, and blown linseed oil plasticizers are also used. Diethyldiphenyl and dicyclohexyl phthalates, butyl benzyl phthalate and phosphate ester including 2- ethylhexyl diphenyl phosphate polyester, chlorinated naphthalenic, and adipate diesters are useful for polyvinyl formal. By proper choice of plasticizer type and level, the physical–mechanical, chemical, and adhesion properties of these resins can be tailored for a wide variety of applications. Fitzhugh and Crozier 5 have studied the effect of a number of plasticizers on the mechanical properties of polyvinyl acetal resins. TA BLE 60.4 Typical Physical and Chemical Properties of Formvar Polyvinyl Formal Resin Properties ASTM Method a Formvar Resins 5/95E 6/95E 7/95E 15/95E Physical Form White, free-flowing powder Volatiles, maximum, % 2.2 2.2 2.2 2.2 Molecular weight × 10 –3 (weight average) (1) 25–35 35–45 40–60 70–150 Solution viscosity 15% by wt, MPa + 8 (2) 140–280 250–500 325–675 1800–3500 Resin viscosity (2) 8–12 12–15 15–20 37–53 Specific gravity, 23 ° /23 ° ( ± 0.002) D792–50 1.227 1.227 1.227 1.227 Burning rate, cm/min D635–56T 2.0 2.3 2.3 2.5 Refractive index ( ± 0.0005) D542–50 1.502 1.502 1.502 1.502 Water absorption (24hs), % D570–59aT 1.2 1.2 1.2 1.2 Hydroxyl content, as % polyvinyl alcohol D1396–58 5.0–6.5 5.0–6.5 5.0–6.5 5.0–6.5 Acetate content, as % polyvinyl acetate D1396–58 9.5–13.0 9.5–13.0 9.5–13.0 9.5–13.0 Formal content, as % polyvinyl formal, approx 82 82 82 82 Chemical b Resistance to Weak acids D543–56T E E E E Strong acids D543–56T E E E E Weak bases D543–56T E E E E Wtrong bases D543–56T E E E E Organic solvents Alcohols D543–56T G G G G Chlorinated D543–56T P P P P Aliphatic D543–56T E E E E Aromatic D543–56T G G G G Esters D543–56T G G G G Ketones D543–56T G G G G a The ASTM method noted for hydroxyl content and acetate content refers specifically to polyvinyl butyral resins. However, the same method is applicable to the polyvinyl formal resins. All other properties were determined by ASTM methods except: (1) molecular weight was determined by SEC/LALLS in hexafluoroisopropanol; (2) solution viscosity was determined in 15% by weight solutions in 6:40 toluene/ethanol at 25 ° C, using a Brookfield viscometer. Resin viscosity — 5 g resin made to 100 ml with ethylene dichloride — measured at 20 ° C using an Ostwald viscometer. b Key: E, excellent; G, good; F, fair; P, poor. Source: Butvar/Formvar Brochure, publication no. 6.70E, Monsanto Chemical Company, Plastics and Resins Division, St. Louis, MO. DK4036_book.fm Page 7 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC 60 -8 Coatings Technology Handbook, Third Edition 60.3.5 Toxicology Butvar resins are regulated by the U.S. Food and Drug Administration under the Code of Federal Regulations, as indirect food additives. Butvar resins have also been subjected to acute toxicity studies on laboratory animals. Subject to the appropriate regulations, they are useful in a number of packaging applications for both fatty and aqueous foods. Both Butvar and Formvar resins have flash points in excess of 370 ° C. The lower explosive limit (LEL) for Butvar dust in air is 20 g/m 3 . Although these materials are considered to be nontoxic in ordinary everyday handling, good industrial hygienic practices should be observed when using them. TA BLE 60.5 Typical Mechanical, Thermal, and Electrical Properties of Formvar Polyvinyl Formal Resin Properties a ASTM Method Formvar Resins 5/95E 6/95E 7/95E 15/95E Mechanical Te nsile strength, MPa Yield D638–58T 59–66 59–66 59–66 59–66 Break D638–58T 52–59 52–59 52–59 52–59 Elongation, % Yield D638–58T 7777 Break D638–58T 50 50 50 50 Modulus of elasticity (apparent), GPa D638–58T 2.7–3.1 2.7–3.1 2.7–3.1 2.7–3.1 Flexural strength, yield, MPa D790–59T 117–124 117–124 117–124 117–124 Hardness, Rockwell M D785–51 150 150 150 150 E D785–51 65 65 65 65 Notched Izod impact strength (1.25 cm × 1.25 cm), J/m D256–59 70 70 70 70 Thermal ( °° °° C) Flow temperature, 6.9 MPa D569–59 140–150 140–150 140–150 160–170 Glass temperature b 103–113 103–113 103–113 103–113 Heat distortion temperature D648–56 83–87 85–90 85–90 87–93 Heat-sealing temperature c 96 96 99 107 Electrical Dielectric constant 50 Hz D150–59T 3.2 3.2 3.2 3.4 1 kHz D150–59T 3.3 3.3 3.3 3.0 1 MHz D150–59T 3.1 3.1 3.1 2.8 10 MHz D150–59T 3.0 3.0 3.0 2.8 Dissipation factor × 10 3 50 Hz D150–59T 8.1 8.1 8.1 8.7 1 kHz D150–59T 10 10 10 10 1 MHz D150–59T 21 21 21 21 10 MHz D150–59T 19 19 19 18 Dielectric strength (3.2 mm thickness), V/m Short time D149–59 24 13 13 12 Step by step D149–59 12 12 12 13 a Conversion factors: MPa × 145 = psi; GPa × 145 × 10 3 = psi; J/m × 53.38 lb-ft/in. b Glass temperature ( T g ) was determined by differential scanning calorimeter. c Heat-sealing temperature was determined on a 25 m dried film on paper, cast from a 10% solution in 60:40 toluene/ethanol. A dwell time of 1.5 sec at 414 kPa (60 psi) line pressure was used on the heat sealer. Source: Butvar/Formvar Brochure, publication no. 6.70E, Monsanto Chemical Company, Plastics and Resins Division, St. Louis, MO. DK4036_book.fm Page 8 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Polyvinyl Acetal Resins 60 -9 60.4 Surface Coating Applications 60.4.1 Polyvinyl Butyral 2,8 The inherent properties of adhesion to a wide variety of surfaces, film toughness and chemical/solvent resistance, and film clarity of the polyvinyl butyral resins makes them the vehicle of choice in a wide variety of specialty coating applications. They adhere tenaciously to most polar surfaces: wood, glass, metals, ceramics, pigments, etc. Their high binding efficiency allows them to be used at very high pigment loadings. Ceramic films are typically cast in thicknesses from fractions of a mil to several millimeters, TA BLE 60.6 Solubility of Formvar Resins a Solvent Formvar Resins 15/95E, 7/95E, 6/95E, 5/95E Acetic acid (glacial) S Acetone I Aniline S Benzene I Butyl alcohols I Butyl acetate I Carbon disulfide I Cresylic acid S Cyclohexanone I Diacetone alcohol I Diisobutyl ketone I Dimethyl sulfoxide S N, N –Dimethylacetamide S N, N –Dimethylformamide S Ethyl acetate, 99% I Ethyl acetate, 85% I Ethyl alcohol, 95%, or anhydrous I Furfural S Hexane I Isopropyl alcohol, 95%, or anhydrous I Methyl acetate I Methyl alcohol I Methyl benzoate S Methyl butynol S Methyl cellosolve acetate I Methyl ethyl ketone I Methyl isobutyl ketone I Methyl pentynol S N –Methyl–2–pyrrolidone S Nitropropane I Pentoxol I Propyl alcohols I Phenol S Propylene dichloride I Te trachlorethane S Te t r a h y d rofuran S To luene/ethyl alcohol (95%) (60:40 by weight) S To l u e n e I VM&P Naphtha I Xylene I Xylene- n -butyl alcohol (60:40 by weight) I a Key: S, Completely soluble; I, insoluble or not completely soluble. Source: Butvar/Formvar Brochure, publication no. 6.70E, Monsanto Chemical Company, Plastics and Resins Division, St. Louis, MO. DK4036_book.fm Page 9 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC 60 -10 Coatings Technology Handbook, Third Edition using 4 to 5% Butvar B-76 as the sole binder 6 ; most permanent coatings applications will require con- siderably higher binder levels than this for adequate film strength. Polyvinyl butyral resins have been used as the binder of choice in thermophotographic and photographic coatings, 7 in photoconductive coatings, in electrophotographic coatings, and as a coating on optical recording disks, all of which depend on film toughness, binder efficiency, and optical clarity. Their toughness, chemical and heat resistance, and binding efficiency render them useful in powder coatings and photothermographic coating applications. Polyvinyl butyrals are used extensively as wood coatings, where their resistance to natural wood oils makes them a primary choice for sealers and wash coats. An example of an application on the Western Pine Association Knot Sealer number WP578 is given in Table 60.8. A well-known application of polyvinyl butyrals is in the manufacture of wash primers for the priming of metal surfaces to be used in hostile environments (e.g., the hulls of naval vessels). There are a number of formulations available, both single- and two-package systems. Another example of a metal coating based on polyvinyl butyral is Metal Coating Other coating applications of the polyvinyl butyrals include solder masks for printed circuit board manufacture, heat-fusible wire coatings, and zinc oxide-based photosensitive paper coatings; they also serve as the binder/vehicle for iron oxide in the production of magnetic recording tapes. They are widely used as toughness/flexibility/adhesion promoters in the production of inks for letterpress, flexographic, and gravure printing, and as a component in toners for reprography. 60.4.2 Polyvinyl Butyral Dispersions The dispersion of plasticized polyvinyl butyral in water, marked, by Monsanto as Butvar dispersion BR, 4 is widely used as a permanent surface size in critical textile applications, e.g., seat belt and parachute webbing, where the toughness of the butyral film lends outstanding abrasion resistance to the fabric. The relatively high surfactant levels used in the manufacture of this dispersion reduce the inherent adhesion of the resin to most highly polar surfaces such as metals and glass. This property is used to advantage in the preparation of removable coating for temporary protection of sensitive surfaces. This dispersion TA BLE 60.7 Properties of Butvar Dispersion BR Property Description/Value Form Milk-white aqueous dispersion of plasticized polyvinyl butyral Total solids 50.0–52% Viscosity 500–1500 mPa a pH 8.0–10.5 Particle size Most particles between 0.25 and 1.5 µ Particle charge Anionic Plasticizer content 40 parts per 100 parts of resin (28.6% of solids) Pounds per gallon at 25 ° C 8.4 Grams per liter 1008 a Determined on a Brookfield viscometer, LVF, no. 3 Spindle, 30 rpm, 25°C. TA BLE 60.8 Western Pine Association Knot Sealer, WP578: Brush Application Material % by weight Butvar B–90 (Monsanto Chemical Co.) 3.3 Durite P–97 (Borden Chemical Co.) 40.0 SDA 35A, 95% ethanol 56.7 100.0 Source: Butvar/Formvar Brochure, publication no. 6.70E, Monsanto Chemical Company, Plastics and Resins Division, St. Louis, MO. DK4036_book.fm Page 10 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC 2009, described in Table 60.9. 61 -1 61 Polyimides 61.1 Chemistry and Properties 61- 1 61.2 Uses 61- 2 61.3 Commercial Information 61- 2 Bibliography 61- 2 Polyimides are condensation polymers that contain the imide structure –CO–N–CO– as a linear or heterocyclic unit along the polymer main chain. They exhibit exceptional thermal, thermooxidative, and chemical resistance, and good radiation resistance and dimensional stability, while maintaining an excel- lent balance of mechanical and electrical properties. 61.1 Chemistry and Properties Aromatic polyimides are generally produced by a two-step polycondensation reaction of aromatic dian- hydride with either aromatic diamine or aromatic diisocyanate in a suitable reaction medium. They have the following general structure: The direct production of high molecular weight aromatic polyimides in a one-step polymerization could not be accomplished because the polyimides are usually insoluble and intractable. The polymer chains precipitate from the reaction media (whether solution or melt) before high molecular weights are obtained. Therefore, processing of the aromatic polyimides can be accomplished only with the first step intermediate amic acid varnish, while it is still soluble and fusible. Were it not for the processing difficulties associated with known polymers, polyimides would be enjoying success in many more new application areas. This processing problem was partially overcome by the development of copolymers. The two major commercial polyimide copolymers are an amide-imide known as Torlon, a product of Amoco, and an ether-imide produced by General Electric under the trade name Ultem. Another approach to this pro- cessing problem was dealt with by incorporating a soft aromatic segment and/or aliphatic moiety in the polymer main chain. Among the various efforts to overcome the processing difficulties, one commercial success was achieved by incorporating a totally asymmetric diamionophenylindane isomeric mixture into the polyimide backbone; it is marketed as Matrimid 5218 from Ciba-Geigy. This material is soluble in O O N—R— n B. H. Lee Ciba-Geigy Corporation DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC 62 -1 62 Parylene Coating 62.1 Process 62- 1 62.2 Properties 62- 2 62.3 Applications 62- 3 References 62- 3 62.1 Process The parylene process 1,2 is a means of applying a pinhole-free coating with exceptional conformality and control of thickness. The coatings so produced have excellent dielectric as well as barrier properties. The parylene coating, composed solely of poly ( p -xylylene) (PPX), a family of linear, high molecular weight organic polymers, is grown directly on a substrate by vapor deposition polymerization (VDP). The gaseous p -xylylene monomer (PX) is transformed into a solid polymer coating without passing through an intermediate liquid stage. Since surface forces have no opportunity to alter the cross-sectional profile, the result is a coating of extraordinary uniformity of thickness and continuity. No postdeposition cure is necessary to complete the coating chemistry. The parylene process affords exceptional control of coating thickness. While typically used in thicknesses of 1 to 10 µ m, continuous parylene films have been demonstrated at thicknesses under 500 (0.05 µ m). In principle, there is no upper limit to the thickness to which a parylene film might be grown, but practical constraints of time and cost place an upper bound in the vicinity of 100 µ m. The parylene process is further distinguished by the fact that it is conducted at room temperature. Parylene growth rates actually decrease at high temperatures. There is an advantage in operating the process at subambient temperatures, if such operation is feasible. Another distinguishing feature of the parylene process is that it proceeds without the assistance of a catalyst. Thus, the coating is of remarkable chemical purity with respect to catalyst residues, which in other coating systems can be ionic or ionogenic, or leachable. The monomer is exceptionally reactive. It cannot be stored. It can be handled only as a rarefied, low pressure gas. It is therefore necessary to generate monomer as it is required by the coating process. Monomer is conveniently generated by the pyrolytic cleavage of its dimer, di- p -xylylene (DPX), a [2.2] paracyclophane. Monomer generation from dimer proceeds in quantitative yield with no by-products. Because the temperatures for monomer generation and consumption are so different, monomer trans- port from one site to the other during deposition is a practical necessity. Such transport is done most efficiently when all other gases are absent. For this reason, the commercial process is conducted within a vacuum system. The composition of the coating can be modified to some extent by attaching substituents to the ring carbons of the DPX molecule. Although many versions of parylene process feedstock DPX are known, those that are commercially available at this time include DPXN, the base hydrocarbon; DPXC, with an average of one chlorine atom per aromatic ring; and DPXD, averaging two chlorine atoms per aromatic ring. The coatings prepared starting with these dimers are called Parylene N, Parylene C, and Parylene William F. Beach Consultant DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC 63 -1 63 Nitrocellulose 63.1 Preparation 63- 1 63.2 Solubility 63- 2 63.3 Film Properties 63- 3 Appendix: Typical Properties of RS Nitrocellulose 63- 5 When most people think of nitrocellulose, they think of guncotton, a material that was developed for explosives or gum propellant. But they are only partially correct. Nitrocellulose is one of the oldest and most widely used film formers adaptable to a number of uses. It is derived from cellulose, a material from plants, and therefore a renewable source. Soluble nitrocellulose possesses a unique combination of properties such as toughness, durability, solubility, gloss, and rapid solvent release. As the film former in lacquer systems, it affords protective and decorative coatings for wood and metal. In addition, it finds use in flexible coatings for paper, foil and plastic film, printing inks, and adhesives. This chapter briefly covers the properties, uses, and handling procedures for nitrocellulose and the formulations made from it. 63.1 Preparation Nitrocellulose is the common name for the nitration product of cellulose. Other names include cellulose (tri)nitrate and guncotton. The commercial product is made by reacting cellulose with nitric acid. Cellulose is composed of a large number of β -anhydroglucose units, which are jointed together into a chain. The anhydroglucose units are six-membered rings having three hydroxyl (–OH) groups attached to them. The number of anhydroglucose units in the typical cellulose chain ranges from 500 to 2500 in chemically purified cellulose. 63.1.1 Degree of Substitution Nitric acid can react with these three hydroxyl groups of the anhydroglucose units to form the nitrate ester. Fully nitrated cellulose would then be a trinitrate — that is, a nitrate having a degree of substitution of 3. The calculated nitrogen content of such a fully nitrated cellulose is 14.14%. In practice, however, the maximum nitrogen level that can be achieved is 13.8%. This corresponds to a degree of substitution of 2.9. At this level, nitrocellulose does not process properties that are useful for coatings use. Film forming properties are better at degrees of substitution between 1.8 and 2.3. Daniel M. Zavisza Hercules Incorporated DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC Solvents and Diluents • Viscosity Effects • Blushing • Solution Grades Preparation Degree of Substitution • Degree of Polymerization • Types and Plasticizers • Resins • Cross-Linkable Coating Systems • Safety Considerations 63 -6 Coatings Technology Handbook, Third Edition Chemical and Physical Properties of Unplasticized Clear Film Moisture absorption at 21 ° C in 24 h in 80% relative humidity 1.0% Water vapor permeability at 21 ° C 2.8 g/cm 2 /cm/h × 10 6 Sunlight effect on discoloration Moderate Sunlight effect on embrittlement Moderate Aging Slight Effect of cold water Nil Effect of hot water Nil General resistance: Acids, weak Fair Acids, strong Poor Alkalies, weak Poor Alkalies, strong Poor Alcohols Partly soluble Ketones Soluble Esters Soluble Hydrocarbons Aromatic Good Aliphatic Excellent Oils Mineral Excellent Animal Good Ve getable Fair to good Source: Nitrocellulose (technical brochure), Hercules Incorporated, Wilmington, DE. DK4036_book.fm Page 6 Monday, April 25, 2005 12:18 PM © 2006 by Taylor & Francis Group, LLC [...]... 3 4 5 6 Parts CMC /100 Parts Clay FIGURE 67.2 Zeta potential of kaolin clay with adsorbed CMC at pH = 7 and 25°C [Adapted from R M Davis, TAPPI J., 70(5), 99 (May 1987), with permission.] 50 Viscosity, mPa·s 45 40 35 30 25 20 100 0 10, 000 Shear Rate, 1/sec 100 ,000 FIGURE 67.3 High shear viscosity for kaolin clay and CMC; < clay volume fraction = 0.39 distilled water control: 0 .10 part CMC /100 parts clay;... 10, 000 Shear Rate, 1/sec 100 ,000 FIGURE 67.3 High shear viscosity for kaolin clay and CMC; < clay volume fraction = 0.39 distilled water control: 0 .10 part CMC /100 parts clay; = 0.21 part CMC /100 parts clay; O 0.31 part CMC /100 parts clay [Adapted from R M Davis, TAPPI J., 70(5), 99 (May 1987), with permission.] © 2006 by Taylor & Francis Group, LLC DK4036_book.fm Page 1 Monday, April 25, 2005 12:18 PM... Sodium orthophenylphenate Parts by Weight 30 30 10 13 8 4 0.1 2.9 2 100 TABLE 64.9 Single-Package Casein Glue for Use in Fire Doors Dry Glue Composition Parts by Weight “Adhesive-grade” soybean flour 60-Mesh lactic acid casein Fresh hydrated lime 200-Mesh wood flour Granular sodium carbonate Granular sodium fluoride Granular trisodium phosphate Diesel oil (defoamer) 58 19 7 5 5 2 1 3 100 2 Let stand 15 min... increased collisions between the colloidal particles in the coating These collisions form aggregates that raise the viscosity For good coating performance, it is important to control the viscosity the water phase and to suppress the tendency of the solid particles to aggregate upon collision The viscosity of the water phase increases as the concentration of CMC increases.1 Particle aggregation is a direct consequence... Introduction 65-1 65.2 Properties 65-1 65.3 Applications .65-2 Remoistenable Coatings: Gummed Tape • Photoresists for Photochemical Machining • Dyed Patterns on Glass • Ceramic Stencils • Electrical Insulators • Temporary Protective Coatings • Plating Release Agents • Fish Gelatin in Photographic Coatings • Gelatin Capsules Robert E Norland Norland Products, Inc 65.4 Conclusion ... plants It is used extensively in aqueous paper coatings for controlling coating viscosity Aqueous paper coatings are colloidal suspensions consisting primarily of pigment, such as kaolin clay, and binders such as starch or latex The solid concentrations typically range from 55 to 70% The properties of a coating are determined by colloidal forces acting between particles and by the properties of the suspending... Typical Commercial Formulation for Blood Glue Component Parts by Weight 90% soluble dried animal blood Water at 60–70°F Mix 3 min or until smooth Water at 60–70°F Mix until smooth Ammonium hydroxide, specific gravity 0.90 Mix 3 min Powdered paraformaldehyde (sift in slowly while mixing) Allow to stand 30 min Mix briefly until glue is fluid and smooth 100 80 a 60–120a 6 15 Variable for viscosity control and... analysis of viscosity data using Equation 67.1 suggests that paper coatings, like other concentrated suspensions, flow in ordered layers along streamlines rather like cards in a deck sliding over each other.4 At low shear rates, this ordered structure results in a low viscosity Above a critical shear rate, this ordered structure breaks down and the particles in the suspension collide far more frequently, resulting... and millwork is still possible Mixing directions are as follows: 200 lb of water at 60 to 70°F and 100 lb of dry glue (as in Table 64.9) for the following steps: © 2006 by Taylor & Francis Group, LLC DK4036_book.fm Page 11 Monday, April 25, 2005 12:18 PM Soybean, Blood, and Casein Glues 64-11 15 U.S Department of Agriculture Forest Products Laboratory, “Casein glues: Their manufacture, preparation and... machine, a coating should have a shear thinning viscosity that decreases as the shear rate increases Typical viscosities range from about 3000 mPa⋅s at shear rates below 100 0 sec–1 when the coating is mixed and pumped to less than 100 mPa⋅s at shear rates above 1,000,000 sec–1 when the coating is applied to the paper The linear velocity of paper in a coating machine can vary from less than 450 m/min . fraction = 0.39. distilled water control: 0 .10 part CMC /100 parts clay; = 0.21 part CMC /100 parts clay; O 0.31 part CMC /100 parts clay. [Adapted from R. M. Davis, TAPPI J., 70 . 50.0–52% Viscosity 500–1500 mPa a pH 8.0 10. 5 Particle size Most particles between 0.25 and 1.5 µ Particle charge Anionic Plasticizer content 40 parts per 100 parts of resin (28.6% of solids) Pounds. D150–59T 3.1 3.1 3.1 2.8 10 MHz D150–59T 3.0 3.0 3.0 2.8 Dissipation factor × 10 3 50 Hz D150–59T 8.1 8.1 8.1 8.7 1 kHz D150–59T 10 10 10 10 1 MHz D150–59T 21 21 21 21 10 MHz D150–59T 19