Use of Different Adhesives in Postpress (V)

Fifth, synthetic resin adhesive material

Synthetic resins, also known as synthetic resins, are resins obtained by the polymerization or polycondensation of monomers. Synthetic resin adhesives often used in the post-printing process include: polyvinyl acetate, polyvinyl alcohol, 107 glue, EVA hot melt, and the like.

(1) Polyvinyl acetate (PVAC).

constitute:

Polyvinyl acetate is a polymer that is polymerized from vinyl acetate monomers. According to different polymerization methods, there are solution type and emulsion type, and the binding type is emulsion type. Because of its color, it is also called white glue or latex.

performance:

PVAC is a milky white viscous liquid, slightly acidic, soluble in a variety of organic solvents, and resistant to dilute acid and dilute alkali, is not afraid of insect bites, no mildew, is harmless to the human body. PVAC cured adhesive layer is colorless and transparent, it will not cause paper pollution, and it is easy to wash water-soluble emulsion, can be easily diluted, easy to use; PVAC plastic layer after drying toughness, cutting does not damage the blade, suitable for binding use .

The disadvantage is that this binder has poor water resistance and poor heat resistance.

Usage:

PVAC adhesives are used in a wide range of applications and are particularly suitable for the bonding of porous materials such as paper, fabric, leather, and wood.

PVAC adhesives can be used for single-sheet, double-sheet, pulp back, book back, book back, bag cover, lining, etc., and can have good results.

PVAC binders can be used in combination with flour pastes, carboxymethyl cellulose, etc. to increase the viscosity of the fluid while reducing costs.

PVAC is a water-soluble glue. Drying speed is similar to paste, it is slow, and it is not easy to set. If used to paste hardcover bookcases, the bookcase will cause warpage due to moisture penetration and short drying time.

The PVAC adhesive and the 504 resin blend can be bonded to a PVC coated coverstock.

(2) Polyvinyl alcohol (PVA) binders

Vinyl acetate is a binder obtained by alcoholysis in an alcohol solution at a temperature of 45-48° C. under the action of an alkali catalyst.

performance:

PVA is a white flocculent or powdery polymer compound that dissolves in water and is a colorless, transparent, viscous liquid after melting.

The performance of PVA binders is determined by the structure and degree of alcoholysis of polyvinyl acetate. Polymers with high degree of alcoholysis have very high water resistance; alcohols with low solubility (87%-89%) are easily soluble in water; when the alcohol solubility drops, the solubility of water decreases.

The PVA with a high degree of polymerization has a large molecular weight, a good film forming property, a high viscosity, and a strong viscosity, but has poor water solubility. The degree of polymerization is high, medium, and low, and the PVA binder used for binding must not only consider its degree of polymerization, but also its water solubility.

Usage:

PVA adhesive is a hot sol. Bonding paper, cardboard, hardcover shells, fabrics, etc. have a good effect. Because it is cooled, solidified and dried, the setting is better.

Polyvinyl alcohol binders are less expensive than polyvinyl acetate, but their bond strength is not as good as that of PVAC, but they are more expensive than flour pastes. They are a commonly used synthetic resin binder.

(3) 107 synthetic resin bonding material.

constitute:

107 Synthetic resin binder is a water-soluble polyvinyl formal with a clear or slightly yellow transparent viscous appearance. When used, it can be diluted with water by stirring.

performance:

107 adhesive bond, stable performance. Binding can be used to bind single pages, double pages, linings, covers, pulp backs, etc., and the effect is better than flour paste. The film has good elasticity, no brittleness, and no deliquescence deformation. 107 glue is a hydrosol, can not be used below 0 °C, nor can it be exposed to sunlight for a long time, so as to avoid separation of water glue, viscosity reduction, aging deterioration.

107 glue can be used according to the required viscosity modulation, too thick can be added when the water (note the water temperature), the viscosity is too low, the appropriate addition of some plasticizers. When it is found that there is a separation of water glue, a small amount of ethanol can be added to make the glue block uniformly dissolved.

107 glue can also be mixed with PVAC adhesive to increase its viscosity.

Usage:

107 adhesives have a wide range of uses and can be widely used in construction, shoemaking, printing and other industries. 107 glue used in the binding industry is mainly used instead of flour paste.

107 glue is generally not used to paste the shell (mainly due to its water-soluble, easy to penetrate, drying is not easy to set, will cause the book shell curled uneven)

(4) EVA hot melt

constitute:

EVA hot melt is a copolymer of ethylene and vinyl acetate formed under high pressure. Since ethylene and vinyl acetate are different in composition, the molecular weight of the hot melt obtained by polymerization is also different, and its performance is also different, and it can be selected as needed.

performance:

EVA hot melt is a solid, fusible polymer that does not require solvents and does not contain moisture. The EVA hot melt is a solid at room temperature, heated to a certain degree and becomes a fluid with a certain viscosity. The melted EVA colloid is a light brown translucent body.

EVA hot melt is 100% solid and completely melted by heating when it becomes a fluid. When it is heated to 80°C, the colloid starts to move slowly. As the temperature increases, the flow gradually increases. When the temperature rises above 250°C, the colloid starts to age. As the quality deteriorates, the viscosity decreases and the film becomes brittle. The curing process of the hot melt is completed by cooling. It is a fast curing, excellent performance adhesive material. Its drying speed is unmatched by any kind of adhesive, and can be cured in only a few seconds. , The sticky objects are firmly bonded together.

Usage:

EVA hot-melt adhesive can bond porous and non-porous materials, but the adhesive surface should not be too large, too large adhesive surface will affect the speed of application and cause no adhesion, because the glue curing time is only more than ten seconds at most . EVA hot melt is mainly used on high-speed production lines, because the wireless glue-binding line is a high-speed production of books and processing equipment, the speed is generally 55 / min three, the use of hot melt on this rapid processing equipment Bonding books This book is very adaptable, it can shorten the drying time after the glue, improve the binding speed.

The hot melt produced in our country is divided into high speed and low speed.

According to the texture of the adherend, it can be divided into several types, such as offset paper glue and coated paper glue; it is divided into side glue and back glue to meet the requirements of different strengths.

(5) Vinyl acetate-ethylene emulsion (VAE)

constitute:

The VAE binder is a milky white liquid that is an aqueous dispersion of a copolymer of vinyl acetate and ethylene.

performance:

The ethylene component makes the copolymer film flexible, which is much better than the brittle polyvinyl acetate homopolymer. This emulsion is very stable and has a slight vinyl acetate taste and can be stored for 6 months under natural conditions.

Usage:

This kind of material used for binding is mainly bonded to PVC type fabrics, such as PVC coating cover paper and ring liner.

(7) Paper plastic composite adhesive.

constitute:

The paper-plastic composite adhesive is a copolymer of acrylate and styrene.

performance:

Appearance is white liquid. The adhesive has good adhesive properties and the required viscosity and elasticity of the film. The paper-plastic composite adhesive is water-dispersible, non-flammable, non-toxic, harmless, non-irritating odor, etc. It is a water-soluble adhesive material with strong bonding ability.

Usage:

Paper-plastic compound is mainly used for paper and plastic bonding in binding. This kind of adhesive can be used manually and mechanically. It is easy to operate and firmly bonded.

(8) 504 Binder

performance:

The 504 adhesive is a transparent liquid adhesive that can be used alone or in combination with other adhesives and is very viscous.

Usage:

In binding, it is generally mixed with other binders. If 504 binder is mixed with polyvinyl acetate latex or flour slurry, it can bond paper and PVC coated paper, paper and plastic film, and the bonding effect is good.




Source: Bison