Selection of common bonding agents for modern binding
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Adhesive is one of the main materials for bookbinding. The choice of bonding agent has a direct relationship with the quality of the book's processing. If it is properly selected, the finished book will be firm and flat, otherwise it may cause serious quality problems.
A substance in which a bonding agent bonds two objects firmly and is an indispensable material in binding. Some books, such as the perfect binding book, are all joined together with a binder. Many areas in the country have many problems due to improper selection or unreasonable use of adhesives. For example, the three sides of the hardcover book ring village are not sticky (flash), the book seals are warped after the paste, and the wireless adhesive book is dropped and leaked. The inequality between the rubber sole and the back of the book is extremely serious. There are unqualified products and the society reflects a lot. It should be paid attention to by all parties.
Based on these circumstances, I will introduce the type, performance and use of the adhesive here for peer reference.
First,Synthetic resin binder
Synthetic resin, also known as synthetic resin, is a resin obtained by gathering or polycondensing monomers. Synthetic resin binders are widely used, convenient, and a wide variety of bonding materials. There are mainly the following for book binding.
1. Polyvinyl acetate (PVAC) bonding material
Polyvinyl acetate is a polymer made by polymerizing vinyl acetate monomers. According to different polymerization methods, it is divided into two types: emulsion type and solution type. The emulsion type used for binding is white, because of its color whitening, it is also called latex or white glue.
1 polyvinyl acetate performance
PVAC is a milky white viscous liquid with a slightly acidic nature. It can be dissolved in a variety of organic solvents, and can withstand 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 adhesive layer is a colorless transparent body, which does not pollute the paper and the like, and is an aqueous solution, so it is easy to wash, and the viscosity can be adjusted at will. Easy to use. After drying, the PVAC adhesive layer has good toughness and can be cut without damaging the blade, which is suitable for binding. This kind of glue has many advantages, but the disadvantage is that the water resistance is poor and the heat resistance is also poor. However, as long as the performance of the storage is not affected, it is the longest use time (the binding has been used for more than 20 years) and the most A popular and popular synthetic resin bonding material.
2PVAC binder index
At present, the quality index requirements of PVAC adhesives produced in China are: milky white thick liquid, uniform and no obvious particles in the body: solid content 50% ± 2%: viscosity 1 ~ 2 microns; pH value 4 ~ 6: effective period is generally one year (custody It can last for a year and a half).
Use of 3PVAC adhesive
PVAC adhesives are used in a wide range of applications and are particularly suitable for bonding porous materials such as paper, fabric, cardboard, leather, wood, etc. Pay attention to the following points when using:
A. Before use, use cold water (not less than 0 ° C) or hot water (not higher than 36 ° C) to prepare the desired viscosity of the binder. The more water is added, the lower the viscosity, and the mixing should be even when adding water.
B. It can be used for bonding single, double-page paper, pulp back, sticky book back, cover (paperback), etc., and has good adhesion effect.
C. It can be mixed with flour paste, carboxymethyl cellulose, etc. to increase the consistency of the fluid and reduce the cost.
D. When using in winter, pay attention to cold protection. In summer, it should be protected against heat. It should not be stored and used for longer than O°C and above 36°C. Otherwise, the limbs will deteriorate and precipitate. In order to prevent cold, an appropriate amount of dibutyl phthalate may be added.
E. After the use of the remaining glue, pay attention to the seal (especially after opening the barrel) is not in contact with the air, it is best to pour some cold water on the rubber surface to avoid the waste of dry knot hardness.
F. Paste book envelopes are best not to use this glue. Because PVAC is a water-soluble binder, the drying speed (same as the rough surface paste) is slow, the penetration is strong, and it is not easy to shape. After the paste, the book cover will be extremely curved due to water penetration and delay of drying time. .
After the G.PVAC adhesive is mixed with the 504 glue, the PVA coating cover and the ring-lined paper have a good effect.
The drying of PVAC adhesive relies on water evaporation. The drying speed is directly related to temperature and relative humidity. The drying speed is relatively slow: if it is used in the linkage production line, it needs to add drying equipment, such as far infrared ray, high frequency medium heating, etc. The dry temperature should not be too high.
2. Polyvinyl alcohol (PVA) bonding material
The polyvinyl acid binder is a white floc or powdery polymer compound which is soluble in water and is a colorless and transparent viscous liquid after hot melt.
1 polyvinyl alcohol bonding performance
The performance of PVA is determined by the structure of the polyvinyl acetate and the degree of alcoholysis. When the degree of alcoholysis reaches 99% to 100%, a highly crystalline polymer can be obtained, and the water resistance is excellent; when the degree of alcoholysis is 87% to 89%, it is easily soluble in water; when the degree of alcoholysis is decreased again, The solubility of water is reduced again. The PVA with high degree of polymerization has a large molecular weight, good film forming property, high viscosity, strong viscosity, but poor water solubility. The degree of polymerization is classified into high, medium and low, that is, 500 to 700 is a low degree of polymerization: 700 to 1500 is a medium degree of polymerization: 1500 to 2000 is a high degree of polymerization. Binding PVA binders should consider both the degree of polymerization and water solubility.
2 use of polyvinyl alcohol
PVA adhesive should be added with water to heat and melt into a viscous liquid. The methods and precautions for use are as follows:
A. According to the required viscosity, add appropriate amount of water in the glue, and place it in a container to heat it into a uniform and viscous liquid. When heating, use steam or water bath. Do not directly contact the heater. The heating temperature in the glue should not exceed 100. °C, in case it deteriorates.
B. The PVA is used at a temperature of 45 ° C ± 10: it can be mixed with flour paste at a suitable temperature.
C. PVA is a heating glue, water is not easy to penetrate, drying is slow, and adhesive cardboard, paper, fabric, etc. are available, and the hardcover book case can also be used.
Polyvinyl alcohol bonding materials are inexpensive and have good bonding properties, and are a very common bonding agent.
3. Hot melt win (EVA)
Hot melt adhesive is a 100% soluble polymer that does not require solvent or moisture. The hot melt is a solid at a normal temperature, and the liquid is heated to a certain extent to become a fluid and has a certain viscosity: the molten hot melt is a light brown translucent body.
1 composition of hot melt adhesive.
The main component of hot melt adhesive is EVA resin, which is a high temperature polymerized object of polyethylene and vinyl acetate; and after being melted at a high temperature with rosin, glycerin, polymerized rosin, paraffin, etc., it is cooled and solidified into a block-like colloid, that is, binding. A block or granular hot melt adhesive. The main component of hot melt adhesives is EVA resin. Because of its current difficulties in polymer processing, it is replaced by imports.
2 hot melt properties
EVA is a 100% solid glue that turns into a fluid that is completely heated and melted at high temperatures. When heated to 80 ° C ~ 100 ° C, the colloid is slow, and as the temperature increases, the flow gradually accelerates. When the temperature rises to 250 ° C, the colloid ages, the color becomes darker, the viscosity decreases, and the glue changes. EVA's colloidal curing process relies on cooling. It is a fast-curing adhesive material with excellent drying speed, which is unmatched by any kind of bonding material.
3 use of hot melt adhesive
EVA can bond both porous and non-porous materials, and the adhesive surface should not be too large, otherwise it will not be able to bond because the curing time of this glue is only a dozen seconds. EVA is mainly used for high-speed production of the perfect binding line, which cannot be used for manual binding operations.
A. The amount of glue should be stored in advance when using it, and it should be heated more than 2 hours in advance to gradually become the required fluid.
B. The fluidity of the colloid can be controlled by temperature. When the viscosity is high (thick), the temperature can be slightly lowered. When the viscosity is low (lean), the temperature can be raised. In the perfect binding machine, the glue can be used at 150 ° C ~ 180 ° C; the second (with a sticky back paper device) coating temperature is about 30 ° C higher than the first glue temperature, that is, the viscosity of the second glue is absolutely The first sticky book back paper cannot be pulled down.
C. The hot melt adhesive curing time is generally 7-13 seconds: the cooling time is generally about 30 seconds. The cooling process on the linked production line is achieved by the extended conveyor method. In a certain period of time, it should be ensured that the colloid has good conditions for cooling and drying, so as to ensure that the book is firmly bonded and beautiful.
D. The conditions for the production of hot melt adhesives should be to ensure normal room temperature. If the room temperature is too low, the curing time will be affected. The adhesive will fall off due to premature drying and poor adhesion (or stickiness) of the adhesive.
3. Paper-plastic composite bonding material
This material is a copolymer of acrylate and styrene and looks like a milky white liquid. The colloid has good bonding properties and the required viscosity and film elasticity. Paper-plastic composite bonding agent uses water as the dispersion medium (water solvent), is non-flammable, non-toxic, harmless, and has no irritating odor. It is a water-soluble bonding material with convenient use and strong bonding ability.
This kind of adhesive is more widely used with the change of the binding materials (such as PVC coated paper, coated paper, plastic cover, etc. in the cover material). It is necessary to use this adhesive in the elbow joint with the paper, especially the cover of the upper material. The hardcover book case and the ring lining are glued. If the three sides are not sticky, the glue can be adhered.
Paper-plastic composite bonding agent can be used for manual binding and machine binding. It is easy to operate, has high viscosity and strong bonding. This kind of adhesive was mass-produced in the mid-1980s, with good effect and rapid popularity, which solved the problem of non-stick quality on the three sides of the ring liner.
Second, animal bonding materials
The use of animal bonding materials has a long history in China. As early as 2,000 years ago, people used animal leather and water to make skin glue for use in the bonding of various objects. This glue is a bonding material obtained from the skin, intramuscular tissue and bone of animals treated with hot water or lime slurry. There are several types of animal bonding materials such as bone glue, gelatin and fish gelatin. Binder is commonly used for binding. Fish glue is widely used for dry fish, so it is basically not used to make bonding materials.
1. bone glue
Bone glue is one of the most widely used animal bonding materials. Its characteristics are: good bonding performance, high strength, low moisture, fast drying, good bonding and setting, low price and convenient use. It is especially suitable for bonding and pasting hardcover book covers, which can get good results.
1 bone glue performance
The main component of animal glue is gelatin skin protein. It is a kind of bone glue with low purity. Bone glue is a brittle lumps solidified body. Collagen is a protein that is insoluble in water. After being heated and treated, it becomes another form of protein called capsule, which is soluble in hot water and has a bonding property.
The rubber film of the bone glue is very strong and elastic after being formed: but the bone glue is not resistant to water. When the water is in contact, the rubber layer will expand and lose the bonding strength: the corrosion resistance is also poor, and the temperature is too high and the humidity is too large.
2 use of bone glue
When using bone glue, first soak the bone glue for about 10 hours with equal or slightly more water (preferably with hot water) to make the rubber block soft, and then heat it to about 75 °C to make it a glue. The ratio of glue to water should be determined according to the desired viscosity. For example, the viscosity of water is low and thin: the viscosity is high and thick. When the hot glue is used, the glue temperature should not be too high. When the temperature exceeds 100 °C, the viscosity will decrease due to molecular degradation, and the glue will deteriorate. The bone glue has a small amount of precipitation during use, so it is necessary to add the water well to carry out the necessary stirring to adjust the viscosity and fluidity. Bath heat must be used for hot glue, and it should never be heated directly by the container for storage glue.
The bone glue should be kept at a certain temperature before use. Therefore, when water is added during use, the added water and the colloid temperature should be basically the same, and cold water should not be added. Because the bone glue should maintain a certain temperature (75 ° C ± 10 ° C), the temperature of the glue will drop suddenly after the addition of cold water, which will affect the bonding effect. When using bone glue, the speed of coating should be fast and uniform. Do not use too much glue to cause unevenness of the rubber layer and penetration of glue and leakage.
2. gelatin
The gelatin component is similar to bone cement, but the purity is higher and the colloid is transparent. The raw materials for making gelatin are high quality fresh animal skin, scraps and bones. The melting temperature and coagulation temperature of gelatin are different from those of bone glue. Although the purity of gelatin is high, it still contains some plasticizers. These plasticizers can absorb moisture from the air to prevent the bonding layer from drying excessively and becoming brittle.
Gelatin can be added to the corresponding water before use. It can be completely melted into the required glue at about 50 °C. The usual glue temperature is 40 ° C ~ 70 ° C, not less than 30 ° C can still be used. This kind of glue is better than bone glue and has the same characteristics as bone glue. It is a kind of high-quality bonding material in animal cavity, but the price is higher and should not be used in large quantities, otherwise it will increase the cost.
A. In order to prevent the animal glue layer from becoming brittle after drying, an appropriate amount of glycerin may be added. Make the film have a certain flexibility.
B. In order to prevent mildew and deterioration of the glue (especially when the temperature is high in summer), an appropriate amount of preservative such as carbolic acid may be added to the glue.
C. In order to prevent the rubber color from increasing, some brighteners such as titanium dioxide may be incorporated in an appropriate amount.
D. In order to increase the drying speed of the film at room temperature, a small amount of urea can be added.
E. When using the machine paste, the glue is prone to bubbles, resulting in uneven coating. For this purpose, a small amount of crystal alcohol or silicone liquid, tributyl phosphate, etc. may be added.
The above additives must be stirred evenly after adding the glue to be used.
A large part of the quality problem of binding is caused by improper use or improper selection of bonding materials. Therefore, understanding the types, performances and uses of commonly used binding materials and improving the understanding of bonding materials is an important aspect to ensure product quality.