Books and periodicals binding glue is mainly used in the process of wireless binding, hardcover book core backing, shell making and book covering, and paperback covers for books, magazines and manuals. There are the following types of binding glue: starch paste adhesive (starch paste, dextrin), animal glue (bone glue), cellulose binder, synthetic resin binder (polyvinyl acetate, polyvinyl alcohol, hot melt adhesive) Wait.
1. starch paste adhesive
(L) Starch paste. Starch paste (also called paste) for book binding is mainly made from starch extracted from wheat, corn, potato and rice, and the starch (5% to 12%) and water (95% to 88%) are heated to 80 ° C Made from above. Master the correct modulation temperature, the paste will have a strong bonding force. When the temperature is too low, the starch cannot be completely gelatinized, the bonding strength is weak and it is not easy to use; when the temperature is high, the paste will gradually become a glass-like transparent body, and the temperature will continue to decrease, which will quickly reduce the viscosity of the paste Knot force.
Paste is a commonly used adhesive material for binding. It is widely used for the bonding of paper, bitch of fabric and paper, adhesive cover, ring lining, pulp back, etc. It is not suitable to bond the processing parts that require high bonding strength. The paste material has a wide range of sources, simple production, tasteless, non-toxic, low cost, and easy to use. The paste has a certain adhesion fastness, but it is easy to absorb water and deliquesce, which makes the adherend fall off. Paste is easy to ferment, moldy and spoilage, in order to prevent spoilage, a small amount of formaldehyde is often added, so it is best to use it now.
(2) Dextrin. The raw material of dextrin is still mainly starch. Compared with paste, it has strong viscosity, quick drying and good transparency. It can be placed for a long time without deterioration, and it is widely used.
Dextrin is not only soluble in hot water, but also soluble in cold water to make various concentrations of binders. Generally, a dextrin aqueous solution with a concentration of 45% to 50% is used as a binder for paper and fabrics.
After dextrin is dried, the film layer is relatively brittle, and the adhesion is not strong. For example, if dextrin sticks to lacquer wood and paper, it can be easily peeled off from the dextrin layer after drying. To this end, 1% to 2% of glycerin can be added to improve the elasticity of the film; adding 0.65% to 1% of borax can improve the adhesion fastness of dextrin.
2. Bone glue
The main component of bone glue is gelatin prion protein, low purity is called bone glue or hide glue, and high purity is called gelatin. Bone glue is a solid, purulent lump at room temperature. It cannot be dissolved in cold water, but it can absorb water and swell. The animal bones, skins, and horns are used as raw materials to extract glue protein with adhesiveness.
Bone glue has high bonding strength and good shaping. Due to its low water content and fast drying speed, it is used to bond hardcover book shells, book back cloth, book back paper, and wall cloth. Bone glue is resistant to water for a long time. It will swell the glue layer when exposed to water and lose its bonding strength. If the water content exceeds 20%, it will spoil and deteriorate.
When using bone glue, you should first soak the water in the proportion of 1 part of the glue and 2 parts of the water for about 10 hours. When using it, heat it to 70 to 75 by using a bath heat method (it will melt into a liquid, and the liquid can flow normally Use. When the heating temperature exceeds 100 ℃, the glue is easy to age and deteriorate. Because animal glue has a wide range of uses and limited sources, it has been gradually replaced by synthetic glue.
Gelatin is rarely used in book binding, because of its high price, it is generally used in high-end picture books or special processing.
3. Cellulose adhesive
Cellulose adhesive is also known as paper wool paste, without grain paste. The cellulose adhesive used in book binding is carboxymethyl cellulose adhesive. Paper wool pastes are sold without commodities, most of which are processed by the printing house with the cut edges. Generally, it is made by crushing the paper wool, by chemical method, alkali land, ether ratio, and then adding water through neutralization treatment. Because of its wide source of raw materials, it has been used in the printing industry.
The paper wool paste has good adhesive properties after drying, good elasticity of the film, stable storage performance, no moldy deterioration, no fear of rat biting insects, and is a substitute for starch paste.
Paper wool paste can be used to bond inserts, interleaf pages, package covers, etc. The drying speed is slower than starch paste. If mixed with polyvinyl alcohol, the effect is better.
4. Synthetic resin adhesive
(1) Polyvinyl acetate emulsion adhesive (PVAC), commonly known as white glue or latex, is polymerized by vinyl acetate monomer. Polyvinyl acetate latex liquid is a white viscous liquid, soluble in a variety of organic solvents, resistant to alkenic acid and dilute alkali.
At room temperature, the adhesion strength of the polyvinyl acetate latex liquid is high. After curing, the film is colorless and transparent, flexible, and the latex liquid is non-toxic, tasteless, and does not irritate the skin. In book binding, it can be used for the bonding of single pages, book back paper, book back cloth, pulp back, bag cover, sweeping liner, caulking cloth, gauze, etc.
The appearance of the polyvinyl acetate swelling latex produced in China is milky white silk liquid, the solid content is 50% ± 2%, the viscosity is 3.4 ～ 10Pa · s (20 ℃), and the pH value is 4 ～ 6. When used at room temperature, latex is easy to age when it exceeds 36 ℃.
(2) Polyvinyl acid (PVA). Polyvinyl alcohol is a white or yellowish flocculent or powdery water-soluble polymer. It is insoluble in general organic solvents and can be melted into a colorless and transparent viscous liquid in hot water. Non-toxic, tasteless, good stability, strong adhesion, and antiseptic.
In book binding, it is commonly used in paperback book cover, hardcover book core processing, sticky paper, plug cloth and gauze. Polyvinyl alcohol can be used alone or mixed with paste. Adding 10% to 30% to the paste can improve the adhesion and water resistance of the paste. Adding other substances to the polyvinyl alcohol, such as adding sodium sulfate and potassium alum, can improve the flexibility and water resistance of the polyvinyl alcohol film. The bonding strength of polyvinyl acid is not as good as that of PVAC, but it is higher than that of paste. It is a commonly used binder in book binding.
(3) Hot melt adhesive (EVA). Hot melt adhesive is a solid meltable polymer that does not contain water and does not require solvents. At normal temperature, the hot-melt adhesive is a solid, which is melted after being heated to a certain temperature, and becomes a liquid that can flow and has an adhesive property. There are many types of hot melt adhesives. The hot melt adhesive used for book binding is polyethylene vinyl acetate.
The main component of the hot melt adhesive is a resin formed by copolymerizing ethylene and vinyl acetate under high pressure as the basic resin, which determines the basic properties of the hot melt adhesive. Coupled with a tackifier (rosin) to improve the bonding strength, a viscosity adjuster and setting speed modifier (paraffin) and a small amount of antioxidant to slow down the aging rate of hot melt adhesives. Hot-melt adhesive is mainly used for the wireless binding binding line of books and periodicals. After pre-heating the hot-melt adhesive in the glue pot of the binding line, it is applied to the back of the book after the milling and shaving.
The main characteristics of hot melt adhesives are:
â‘ No water and solvent in the small hot melt cavity. It is solid at normal temperature and becomes a liquid with good fluidity at high temperature, which is not flammable. Harmless to human body;
②The solidification speed is fast. It will solidify within 7 ～ 30s after leaving the glue pot, without drying or adding other curing agents, it is fully adapted to the requirements of high-speed automation, so it has become the best adhesive material for the linkage line of paperless wireless glue factory;
â‘¢Hot-melt adhesive can bond many kinds of materials, especially the cohesion between porous homogeneous materials is stronger, and the cured film has good flexibility;
â‘£The hot melt adhesive can be reheated and used again, and it has strong chemical resistance.
Hot melt adhesives are not heat resistant and have a low softening point. When using hot melt adhesives, heat treatment should be used to melt the solid EVA resin. In order to ensure the quality of wireless perfect binding, the temperature used in hot melt adhesive processing should be strictly controlled. The normal working temperature is 150 ～ 180 ℃, which is the best bonding temperature of the book.
The preheating temperature of the preheating glue pot is usually 15 to 20 ℃ lower than the working temperature. Depending on the thickness of the book block and the quality of the paper, the gluing temperature is also different. The thickness of the book block and the quality of the paper are good. The working temperature of the glue solution can be increased to 175-185 ℃. The higher the temperature of the glue, the faster the flow. When the temperature exceeds 200 ° C, the glue will begin to discolor and aging, and the setting time will become longer, resulting in the cross-linking of the quality of the wireless binding.
(4) Vinyl acetate-vinyl emulsion binder (VAE). VAE emulsion binder is a water dispersion system of vinyl acetate and ethylene copolymer, which is a milky white liquid. This kind of adhesive has not been used in China for a long time, and is mainly used for the bonding of polyvinyl chloride (PVC) coating and processing paper covers and Huancun.
(5) Paper-plastic composite adhesive. The paper-plastic composite adhesive is a copolymer of acrylate and styrene, which is a milky white liquid. Mainly used for paper and plastic bonding, it is a water-soluble adhesive material with convenient use and good bonding ability.
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