Bonding dynamic change to see the quality of glue binding (2)

After milling and back-slotting the surface of the back of the book block through the bookbinding machine's gluing roller, it is evenly coated with a certain thickness (width) of adhesive material - glued hot melt adhesive, and then automatically conveyed Cover bonding. Curing occurs as the adhesive spreads, rheology, penetration, combination, and temperature drop. When the distance between the macromolecules of the adhesive and the surface of the adherend is less than 5A, they will attract each other, generate van der Waals forces or form hydrogen bonds, covalent bonds, coordination bonds, ionic bonds, etc., and insert the wedge-shaped colloid into the milling groove The glue that has penetrated into the pores cures and generates numerous small “glue hooks” that complete the binding process.

Due to the objective reality of the structure and the surface state of the aforementioned adhesive, the poor weatherability of the adhesive composition, and the inevitable aging of the coating process, the peeling strength and uneven peeling of the adhesive layer are eliminated. Strength, impact strength and low temperature toughness are low. At present, the industry lacks effective pre-use non-destructive inspection methods and technical standards for the quality control of adhesives, so that binding companies can hardly distinguish between adhesives with glued hot melt adhesives. In order to verify the high cost of quality.

The composition of the adhesive is: A component: main tack resin 1, main tack resin 2; B component: conditioner 1, conditioner 2, antioxidant.

According to the ratio of tackifying resin and main tackifying resin in component A, the affinity of tackiness agent and tackifier is improved and improved; different regulators are used in blending component B to adjust the softening point and improve the fluidity. Increase the purpose of penetration. Add an appropriate amount of antioxidants to delay or prevent the aging of the adhesive during the synthesis and use of high temperature conditions. It should be said that the design theory of A and B components and the idea of ​​proportional adjustment are correct.

The problem lies in the synthesis and use of the production process and raw material selection and configuration.

The traditional cauldron production method can cause aging of the bonding material in the synthesis process due to the error that the temperature control and conduction cannot be accurately controlled.

The advanced rod extrusion process often produces uneven blends because of the higher viscosity and different softening points.

In order to increase the affinity with the spine after the surface treatment, the appropriate amount of tackifying resin is used to affect the impact strength and the self-ageing gene is significantly faster.

In order to guarantee the rapid and full filling of the milling groove, its fluidity must be improved. The quality and quantity of the modifier modifier used in turn adversely affect its own peel strength and low temperature toughness.

Manufacturers of hot melt adhesives with extremely different levels of technology are peddling the market at low prices and engaging in unfair competition. The binding and processing enterprises choose purchases at price rather than quality, and push glued hot melt adhesives into production errors from both supply and demand.

Third, the binder (binder)

The bookbinding process reform of 7 billion books and books (including 3.6 billion textbooks) per year has promoted the development of bookbinding machines. At present, binding companies use 480 to 600 bar/hour bar type bookbinding machines and 900 to 4,000 bar/hour in parkbooks, and most of them are not equipped with variable frequency systems. In the actual production operation process, it is difficult to ensure the consistency of the groove depth and pitch. Binding-linked thread milling cutter pallets are seriously worn during the processing of domestic-use paper prints and replaced more frequently. After the replacement, it also tends to occur before, after and left and right deviations, affecting the milling back slotting standards.

The serious problem is that the open top of the glue tank has an open structure and its volume is more than 2 hours.

Easy-to-apply, open glue tanks and revolving-rolled rubber wheels increase the contact area of ​​the hot melt adhesive with air to promote sufficient oxidation. In order to ensure even coating, a large amount of hot melt adhesive reserves, and the heating temperature that has been kept during storage, it is the root cause of rapid aging of the hot melt adhesive and reduced strength. The drawing of rubber across the entire length of the perfect binder is an indication of the aging of coated or uncoated rubber.

In addition, the error caused by the quality and sensitivity difference of the heating element itself can be higher than 100oC, which not only makes it difficult to control the aging of the colloid, but it also can not guarantee the overall good fluidity when adding the new compound.

Fourth, adapt to improvement

Based on the status quo of adhesives and the progress of printing technology, adhesives and adhesives should be adapted to the technical improvements of adhesives. Fundamentally speaking, the quality of the binding is determined by the quality of the glued hot melt adhesive and the stability of the glue production process.

1. As a bonding material, the synthesis process of glue-adhesive hot melt adhesives should be based on the improvement of the stability of the blending modification.

The selection of raw materials for the polymerization components should be based on ensuring quality. Through the use of new and superior materials, the contradictions that affect each other and influence each other, such as viscosity and strength, strength and softening point, softening point and fluidity, fluidity and toughness, are solved.

To change the design thinking that simply changes the temperature to change the fluidity and guarantee the gluing effect. Established innovative technology for the development of low-temperature (≤130oC) bottom and edge-adhesive general-purpose new-adhesive hot melt adhesives. Thoroughly solve the qualitative aging caused by melting at high temperature (≥170oC). The new glue-adhesive hot melt adhesive should also have the advantages of small specific gravity (≤0.95), dosage (low spine coating 0.5~1.3mm), and good containment and affinity with paper fiber fluff.

2. Binder's milling cutter should be replaced regularly to keep it sharp and have a good working interface.

The pallets should be grounded to ensure that the work surface is consistent.

Calibrate the accuracy of the colloid melting electric heating element, master the basic error, and change the glue tank under the premise of guaranteeing uniform coating. Minimize the amount of glue in the tank. At the same time equipped with pre-melting tank (≤ 100oC) secondary glue supply device based on coating needs quantitative supply.

Clean up the brush wiper in time, carefully maintain and inspect the suction device to ensure that the paper scraps are completely separated from the booklet album.

3. Conduct technical training for production management and operation personnel to improve their theoretical level and operating skills. Can better handle the problems that arise in the production process.

4, as soon as possible to determine the quality of the glue to ensure the "adhesive hot melt adhesive technology standards" and to facilitate the operation of the company's "hot melt adhesive quality standard inspection methods", standard hot melt adhesive production and use, to eliminate the listing and use of non-standard products .