Bookbinding glue is mainly used in the process of binding, hardcover book core backing, shell and bookcases, and paperback covers for paperback books, magazines and manuals. Staple glue is mainly the following: starch paste adhesive (starch paste, dextrin), animal glue (bone glue), cellulose binder, synthetic resin binder (polyvinyl acetate, polyvinyl alcohol, hot melt adhesive) Wait.
Starch paste adhesive
(l) Starch paste. Book binding starch paste (also known as paste) is mainly from starch extracted from wheat, corn, potato, rice, starch (5% to 12%) and water (95% to 88%) heated to 80 °C Made from above. With the correct modulation temperature, the paste will have a strong binding force. When the temperature is too low, the starch can not be fully gelatinized, and the binding force is weak and difficult to use. When the temperature is high, the paste will gradually turn into a glassy transparent body, and if the temperature continues to rise, the viscosity of the paste will be quickly reduced. Force.
Paste is a glue material commonly used for binding, which is widely used for bonding paper, fabric and paper paste, glue cover, ring lining, pulp back and other processing, and it is not suitable to bond processing areas with high bond strength requirements. Pulp raw materials are widely available, simple to produce, tasteless, non-toxic, low cost, and easy to use. Paste has a certain degree of cohesiveness, but it is prone to deliquesce by absorbing water, which causes the adherend to fall off. Pulps are prone to fermentation, mildew and spoilage. In order to prevent spoilage, a small amount of formaldehyde is often added, so it is best to use it on the spot.
(2) Dextrin. The dextrin raw material is still mainly starch, compared with the paste, its strong viscosity, fast drying, good transparency, can be placed for a long time without deterioration, use a wide range.
Dextrin is not only soluble in hot water, but also soluble in cold water into various concentrations of the binder, generally with a concentration of 45% to 50% dextrin solution for paper, fabric and other adhesives.
After the dextrin is dried, the film is relatively brittle and its adhesion is not strong. If dextrin is used to glue the varnished wood and paper, it can be easily peeled off from the dextrin layer after drying. For this reason, 1% to 2% of glycerin can be added to increase the elasticity of the film; adding 0.65% to 1% of borax can increase the adhesive fastness of the dextrin.
2. Bone glue
The main component of bone glue is gelatin gelatin protein, low-purity bone glue or hide glue, and high-purity gelatin. Bone glue is a solid purulent lump at room temperature. Can not be dissolved in cold water, but it can absorb water and expand. It is made from animal bones, skins and corners as raw materials, and from which glue proteins with adhesive properties are extracted.
Bone glue has high bonding strength and good shaping, and it is used for making hardcover shells, book backs, book backs, and wall tops because of low moisture content and fast drying speed. Bone glue is resistant to water for a long period of time. Water will cause the rubber layer to expand and lose its bond strength. If the water content exceeds 20%, it will spoil.
When using bone glue, first glue 1 part, 2 parts of water should be soaked in water for about 10 hours. When using it, use bath heat method to heat it to 70-75 (it is good to melt into liquid, after the liquid flow is normal When the heating temperature exceeds 100°C, the glue solution will be aged and deteriorated, and due to its wide range of uses and limited sources, it has gradually been replaced by synthetic rubber.
Gelatin is rarely used in book binding because of its high price, which is generally used in high-grade pictures or special processing.
Cellulose adhesive
Cellulose adhesive, also known as paper wool paste, no food paste. Cellulose adhesives used in bookbinding are carboxymethyl cellulose adhesives. The paper wool paste is not sold in the market, but is mostly processed by the printing factory using the cut paper. Generally, after the paper is crushed, it is made by chemically treating the alkali and ether, and then adding water through neutralization. Because of its wide source of raw materials, it has been applied in the printing industry.
The paper wool paste has good adhesive properties after drying, good elasticity of the film, stable storage performance, no mold deterioration, no fear of rat biting insects, and a substitute for starch paste.
Paper wool paste can be used to bond inserts, liners, and covers, etc. The drying rate is slower than starch pastes. 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 formed by polymerization of vinyl acetate monomer. Polyvinyl acetate emulsion latex is a white viscous liquid that dissolves in a variety of organic solvents and is resistant to acids and dilute alkalis.
Under the normal temperature, polyvinyl acetate emulsion liquid has higher bonding strength. After curing, the film is colorless and transparent, and has toughness. The latex liquid is non-toxic, odorless, does not irritate the skin, and is not afraid of insect infestation. In book binding, it can be used for bonding single pages, back-sheets, back-sheets, backs, covers, linings, plugs, gauze, etc.
The appearance of polyvinylacetate emulsion latex produced in China is a milky white silk liquid with a solid content of 50% ± 2%, a viscosity of 3.4 to 10 Pa·s (20°C), and a pH of 4 to 6. When used at room temperature, the latex tends to age when the temperature exceeds 36°C.
(2) Polyvinyl acid (PVA). Polyvinyl alcohol is a white or yellowish flocculent or powdered water-soluble high molecular polymer that is insoluble in common organic solvents and can melt into a colorless, transparent viscous liquid in hot water. Non-toxic, odorless, good stability, strong adhesion, and anti-corrosion.
In book binding, it is often used in paperback cover, hardcover book core processing, sticky cardboard, plug cloth and gauze. Polyvinyl alcohol may be used alone or in combination with a paste. Adding 10% to 30% to the paste can increase the adhesive strength and water resistance of the paste. Adding other substances in polyvinyl alcohol, such as adding sodium sulfate, potassium alum, etc., can improve the flexibility and water resistance of polyvinyl alcohol film. The bonding strength of polyvinyl acid is not as good as that of PVAC, but it is higher than paste, and it is a binder commonly used in bookbinding.
(3) Hot melt adhesive (EVA). Hot melt adhesive is a water-free, solvent-free solid meltable polymer. The hot melt adhesive is a solid at room temperature, melts when heated to a certain temperature, and becomes a liquid that can flow and has a cohesive property. There are many types of hot melt adhesives. The hot melt used for bookbinding is polyethylene vinyl acetate.
The main component of the hot melt adhesive is a resin based on copolymerization of ethylene and vinyl acetate under high pressure, which determines the basic properties of the hot melt adhesive. Together with tackifiers (rosin), glue viscosity and solidification rate modifiers (paraffins), and a small amount of antioxidants to increase the bond strength, the slowness of hot melt adhesives can be slowed down. Hot-melt adhesives are mainly used in wireless glue binding lines of books and magazines. After the hot-melt adhesives are preheated in the glue pot of the gutter, they are brushed onto the back of the books after the milling and backing.
The main features of hot melt adhesives are:
1 Small hot melt chamber does not contain water and solvents. It is solid at room temperature and becomes a liquid with good fluidity at high temperatures and is not flammable. Harmless to the human body;
2 fast solidification. After leaving the plastic pot 7 ~ 30s that is solidified, without drying or adding other curing agents, fully meet the requirements of high-speed automation, so it has become the best adhesive material for the paperback wireless glue factory linkage line;
3 Hot-melt adhesives can bond a variety of substances, especially the porous homogeneous material has stronger adhesion, and the cured film has good flexibility;
4 hot melt adhesive can be reheated and used again, and chemical resistance is strong.
The hot-melt adhesive is not heat-resistant and has a low softening point. When hot-melt adhesives are used, heat treatment is used to melt the solid EVA resin. In order to ensure the quality of the perfect binding, the temperature used for hot melt processing should be strictly controlled. The normal working temperature is 150-180°C, which is the best bonding temperature for the book.
The preheating temperature of the preheated glue pan is usually lower than the working temperature of 15-20°C. According to the thickness of the book block and the quality of the paper, the glueing temperature is also different, the book block is thick and the paper quality is good, and the working temperature of the glue liquid can be increased to 175-185°C. The higher the glue temperature is, the faster the flow is. When the temperature exceeds 200°C, the glue liquid begins to change color and aging, and the solidification time becomes longer, resulting in the poor adhesion quality of the wireless glue binding.
(4) Vinyl acetate-ethylene emulsion binder (VAE). The VAE emulsion binder is an aqueous dispersion of vinyl acetate and ethylene copolymers and is a milky white liquid. This binder is not used in China for a long time and is mainly used for the bonding of polyvinyl chloride (PVC) coated paper cover and ring village.
(5) paper plastic composite adhesive. The paper-plastic composite adhesive is a copolymer of acrylate and styrene and is a milky white liquid. It is mainly used for paper and plastic bonding. It is a water-soluble adhesive material with convenient use and good bonding ability.