Use of different adhesives in post-press processing
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In the modern binding process, different kinds of glues are often used for different requirements. Under what circumstances, what kind of glue is used?
First, animal bonding materials:
(1) bone glue
source:
The main component of bone glue is water-insoluble protein. Another form of protein that is processed by heating and the like is called capsule, which is soluble in hot water and has adhesive properties.
performance:
The gelatin film is very strong and elastic after it is formed, which is determined by the long molecular chain of the bone glue. This long molecular chain can change its arrangement without breaking, and thus produces good elasticity. If a suitable plasticizer is added during use, the elasticity of the film can be increased.
However, bone glue is not resistant to water. When it meets water, the rubber layer will expand and lose its bond strength. Its corrosion resistance is also not good. When the water content in the glue reaches 20% or more, it will easily deteriorate. The high temperature and high humidity will cause changes.
Usage:
It has good bonding performance, high bonding strength, low moisture, fast drying, low price and convenient use, especially for bonding and dextrin bookbinding, which can obtain good results.
Bone glue is best used for paste case, which can avoid or reduce the unevenness of the book cover.
(2) gelatin
source:
The raw materials for making gelatin are high quality fresh animal skin, foot and bone.
performance:
The gelatin component is similar to bone cement, but the purity is relatively high and the colloid is transparent. The melting temperature and coagulation temperature of gelatin are slightly different from those of bone cement.
Usage:
Gelatin is used in the same way as bone glue, but because it is more expensive, it is generally only used in some high-end book catalogues and special processed materials.
Animal glue features:
On the whole, animal glue has good bonding performance, is easy to dry, and is relatively cheap, which is very popular among users. However, when using this kind of glue, only the water is heated and melted, the glue is used, and there are some disadvantages such as brittle cracking after drying. Therefore, some adjuvants should be added during use to change some properties of the glue to obtain better use effect. .
Such as:
Glycerin can effectively prevent the glue layer from becoming brittle after drying.
Preservatives such as stone carbonate can prevent mildew and deterioration of the glue.
Brighteners such as titanium dioxide can improve the color of the glue.
Urea can increase the drying speed of the film at room temperature.
A small amount of terpineol (or silicone liquid, tributyl phosphate, etc.) can eliminate bubbles in the glue.
Second, starch-based bonding materials
A starch-based binding material refers to a binder made of starch extracted from seeds, stems, tubers, and the like of plants.
(1) gluten pulp
source:
The gluten meal is a gluten pulp obtained by washing the gluten pulp or the flour paste obtained by washing the rice flour and wheat flour (flour) with water.
performance:
The gluten slip adhesive has the advantages of fine texture and purity.
Usage:
It is often used to bond the enamel and paper on the paste reel, as well as the wrap angle of the cover of the wire-bound book, the letter of the book, and the book block.
(2) Flour paste
source:
The main ingredient of the flour paste is starch. The paste for binding mainly includes wheat flour paste and glutinous flour paste.
Features:
It has a certain bond strength, which can bond paper, cardboard, cardboard, woven fabric, etc., and can be adjusted to different viscosities according to the requirements of the object to be bonded. However, the stickiness of the flour paste is easy to fall off after being damp. When the temperature is high and the humidity is high, the flour paste is easily fermented, enzymes and corruption. The paste after fermentation has an acid odor, the surface is foamed, the long green hair, the viscosity is greatly reduced, and the normal bonding process is affected.
Usage:
The bonding strength of flour paste is not high, it is suitable for paper, cardboard and fabric and paper paste. It can also be used for the processing of general cover, ring lining and pulp back. It is not suitable to bond work with high bond strength.
Such as:
Single and double pages, backing paper, flat back and flat pack cover, sticky back paper, etc.
(3) Dextrin
source:
Dextrin is a binder made from starch by acid or heat treatment or by action of starch mold.
Features:
Compared with starch, it has high viscosity, fast drying, good transparency and long standing time and is not easy to be spoiled. Dextrin is easily soluble in hot water, slightly soluble in cold water, and has good bonding properties.
Dextrin and paste have the same fluidity and permeability. They can penetrate, diffuse and dry after wetting. They have good bonding effects. Dextrin has many advantages, and the packaging form is small to large, easy to use. very popular.
Usage:
It is suitable for bonding paper, fabric and other objects with certain absorption. It is worth mentioning that the use of dextrin in the confrontation of cardboard is quite extensive.
Starch-based binders can also be mixed with other synthetic resin binders to change their properties for better bonding.
Third, natural resin bonding materials
source:
The natural resin type bonding material is mainly derived from a certain tree species, and is made of a resin material which is discharged after the bark is cut.
Features:
This material is mainly used as an adhesion promoter for hot stamping.
Commonly used adhesion promoters are rosin powder and shellac.
Fourth, cellulose bonding materials
The cellulosic binder material consists essentially of a fiber modified solution. It can bond paper, cardboard, cover, etc., and has good bonding properties.
(1) Carboxymethyl cellulose binder.
source:
Carboxymethylcellulose is an ether of cellulose and glycolic acid, also known as paper pulp paste. This bonding material is obtained by chemically processing paper pulverization.
Features:
The bond strength of the carboxymethyl cellulose binder after drying is stronger than that of the flour paste, the elasticity of the film is good, colorless and transparent, not afraid of biting by the worm, no deterioration of quality, no precipitation, and long storage time. The viscosity can be arbitrarily formulated, and can be mixed with a paste or polyvinyl alcohol to obtain a good bonding effect.
The drying speed of the carboxymethyl cellulose binder is slower than that of the starch-based binder, the adhesion is insufficient at the beginning of the bonding, and the moisture is dried as the moisture evaporates, and the adhesion gradually becomes stronger, and after being completely dried, the bonding is performed. Good strength. Therefore, the pages or covers that are stuck during processing cannot be moved to avoid sticking or sticking.
Usage:
It can replace the use of starch-based bonding materials, such as adhesive covers, paper, liners, and the like.
(2) Methyl cellulose binder.
Methylcellulose is an ether of cellulose and methanol. The colloid is a white or beige flake. It is soluble in cold water. When dissolved, the surface tension is reduced. At 50 °C, the glue will condense, but after cooling, it will return to the original. Solubility. It is non-toxic, has good antibacterial properties, and is also very stable to ultraviolet light.
In the post-pressing process, the cover or the like is often bonded with methyl cellulose, and the glue is easily applied, but sometimes foaming.
Some tributyl phosphate may be added during the preparation to prevent foaming.
5. Synthetic resin bonding materials
Synthetic resin, also known as synthetic resin, is a resin obtained by polymerization or polycondensation of monomers. Synthetic resin-based binders frequently used in the post-press process include polyvinyl acetate, polyvinyl alcohol, 107 gum, EVA hot melt, and the like.
(1) Polyvinyl acetate (PVAC).
Composition:
Polyvinyl acetate is a polymer made by polymerizing vinyl acetate monomers. Depending on the polymerization method, there are solution type and emulsion type. The emulsion type is used in binding, and it is also called white glue or latex because of its color whiteness.
performance:
PVAC is a milky white viscous liquid. It is slightly acidic, soluble in various organic solvents, and resistant to dilute acid and dilute alkali. It is not afraid of insect bites, does not mold and deteriorate, and is harmless to the human body. The PVAC cured layer is colorless and transparent, does not pollute the paper, and is easy to wash with water-soluble emulsion. It can be dilute and easy to use. The PVAC adhesive layer has good toughness after drying, and the cutting does not damage the blade. It is suitable for binding. .
The disadvantage is that the binder has poor water resistance and poor heat resistance.
Usage:
PVAC adhesives are used in a wide variety of applications and are particularly suitable for the bonding of porous materials such as paper, fabric, leather, and wood.
PVAC adhesive can be used for bonding single sheet, double sheet, back, back, back, cover, sweeping, etc., and can have good results.
PVAC binders can be used in combination with flour paste, carboxymethyl cellulose, etc. to increase fluid consistency while reducing cost.
PVAC is a water soluble glue. The drying speed is similar to the paste, it is very slow, and it is not easy to shape. If it is used to paste the hardcover book case, the book case will be warped due to the penetration of moisture and short drying time.
The PVAC adhesive and 504 resin blend can bond the PVC coated cover stock.
(2) Polyvinyl alcohol (PVA) binder
Vinyl acetate is a binder obtained by alcoholysis in an alcohol solution at a temperature of 45 to 48 ° C under the action of a base catalyst.
Performance:
PVA is a white flocculent or powdery polymer compound that is soluble in water and is a colorless, transparent, viscous liquid after hot melt.
The properties of the PVA binder are determined by the structure of the polyvinyl acetate and the degree of alcoholysis. A polymer with a high degree of alcoholysis has a very high water resistance ratio; a low alcohol solubility (87% - 89%) is easily soluble in water; when the alcohol solubility is lowered again, the solubility in water is lowered.
PVA having a high degree of polymerization has a large molecular weight, good film formability, high viscosity, and strong viscosity, but is inferior in water solubility. The degree of polymerization has three types: high, medium and low. The PVA binder for binding needs to consider both the degree of polymerization and the water solubility.
Usage:
PVA binder is a hot sol, which has good effects on bonding paper, cardboard, hardcover book, fabric, etc., because it is cooled and solidified, so it is better shaped.
Polyvinyl alcohol bonding materials are cheaper than polyvinyl acetate, but their bonding strength is not as good as PVAC, but it is higher than the price of flour paste. It is a commonly used synthetic resin binder for binding.
(3) 107 synthetic resin bonding material.
Composition:
The 107 synthetic resin binder is a water-soluble polyvinyl formal having a transparent or yellowish transparent viscous agent. When used, it can be stirred with water to obtain a diluent.
performance:
107 adhesive has strong adhesion and stable performance. Binding can be used to bond single sheet, double sheet, sweeping, cover, and back, which is better than flour paste. The film has good elasticity, no brittleness, and no deliquescent deformation. 107 glue is a hydrosol, can not be used below 0 °C, and can not be exposed to sunlight for a long time, so as to avoid separation of water gel, viscosity drop, aging deterioration.
107 glue can be prepared according to the required viscosity when used. When it is too thick, it can be added with water (note the water temperature). When the viscosity is too low, some plasticizers should be added appropriately. When it is found that there is a separation of water gel, a small amount of ethanol can be added to dissolve the gel evenly.
107 glue can also be mixed with PVAC binder to increase its viscosity.
Usage:
107 adhesives are extremely versatile and can be widely used in industries such as construction, shoemaking and printing. The 107 glue used in the binding industry is mainly used instead of flour paste.
107 glue is generally not used for paste sealing (mainly due to its water solubility, easy to penetrate, slow drying and not easy to shape, which will lead to curling of the book case)
(4) EVA hot melt
Composition:
EVA hot melt is a copolymer of ethylene and vinyl acetate under high pressure. Since ethylene and vinyl acetate differ in composition, the molecular weight of the hot melt obtained by polymerization is also different, and the properties thereof are also different, and 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 normal temperature, and is heated to a certain degree to become a fluid which can flow and has a certain viscosity. The molten EVA colloid is a light brown translucent body.
EVA hot melt is 100% solid. When it becomes fluid, it is completely heated and melted. When heated to 80 °C, the colloid begins to slow down. As the temperature increases, the flow gradually increases. When the temperature rises above 250 °C, the colloid begins to age. Deterioration, viscosity decreases, and the film becomes brittle. The hot melt curing process is completed by cooling. It is a fast-curing, excellent-performance bonding material. Its drying speed is unmatched by any kind of binder. It can be cured in only a few seconds. , the objects to be bonded are firmly bonded together.
Usage:
EVA hot melt can bond both porous and non-porous materials, but the rubber surface should not be too large. The excessive rubber surface affects the application speed and can not be bonded because the curing time of this glue is only a dozen seconds. . EVA hot melt is mainly used in high-speed production lines, because the perfect binding line is a processing equipment for high-speed production of books and magazines. Its speed is generally 55/min, and hot melt is used in this fast processing equipment. Bonding books and magazines is very suitable, it can shorten the drying time after the glue and increase the binding speed.
The hot sols currently produced in China have high speed and low speed.
Also according to the texture of the adherend, it is divided into offset glue and coated paper, etc.; there are side glue and back glue to meet the requirements of different strength.
(5) Vinyl acetate-ethylene emulsion (VAE)
Composition:
The VAE binder is a milky white liquid which is an aqueous dispersion of a copolymer of vinyl acetate and ethylene.
Performance:
The ethylene component imparts softness to the copolymer film 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 material for binding is mainly bonded to PVC fabrics, such as the bonding of PVC paint cover paper and loop liner.
(7) Paper-plastic composite binder.
Composition:
The paper-plastic composite binder is a copolymer of acrylate and styrene.
performance:
The appearance is a white liquid. Its glue has good bonding properties and the required viscosity and film elasticity. The paper-plastic composite binder uses water as a dispersion, is non-flammable, non-toxic, harmless, and has no irritating odor. It is a water-soluble adhesive material which is easy to bond and has strong adhesive ability.
Usage:
Paper-plastic compounding agent is mainly used for paper and plastic bonding in binding. This kind of adhesive can be used by hand or mechanical binding, which is easy to operate and firmly bonded.
(8) 504 binder
Performance:
The 504 binder is a clear liquid binder that can be used alone or in combination with other binders and is very viscous.
Usage:
In binding, it is generally mixed with other binders. If the 504 binder is mixed with polyvinyl acetate latex or flour, the paper and PVC coated paper, paper and plastic film can be bonded, and the bonding effect is good.