Technical Issues and Treatments in Rubber Books (1)

From the print industry using EVA hot melt adhesive books, the time has been more than 10 years of history. Rubber books have a short period, stable quality, low error rate, and light labor intensity. It was welcomed by the publishing industry and the printing industry. In particular, the use of PUR hot melt adhesives has been promoted in foreign countries this year. PUR hot melt adhesives have replaced the common EVA hot melt adhesives. The disadvantages of EVA hot melt adhesives have been compensated by PUR hot melt adhesives. PUR hot melt adhesives are perfect. Binding method. However, in the printing industry today, glue books use EVA hot melt adhesives, and 80% of print quality problems are caused by improper use of EVA adhesives. Therefore, this article analyzes the technical issues in glue-binding and explores common solutions.

First, the type of hot melt adhesive, selection

The research of hot melt adhesives in China began in the mid-1970s. In the past five years, the domestic hot melt adhesive industry has entered a mature stage, and the application range of hot melt adhesives is also expanding. Due to the difference in the composition of the hot melt adhesive and the object of bonding, it has expanded from traditional sanitary products, packaging, printing and binding, etc. to more than ten industries such as clothing, tapes, shoes, refrigerators, cables, automobiles, and buildings. A variety of hot melt adhesives.

The EVA hot melt adhesive used in the publications is a solid, fusible polymer that does not require solvents and does not contain water. The hot melt adhesive is solid at room temperature, and when the hot melt adhesive is heated and melted to about 170° C., it becomes a liquid with a good viscosity; when the temperature in the glue pot rises above 250° C., the hot melt adhesive begins to age. Discoloration, deterioration, viscosity drop, adhesive film becomes brittle, and cannot be used.

At present, the country has not yet promulgated standards for hot melt adhesives for books and periodicals. The factory that produces hot-melt adhesives does not have a unified quality index system. Each factory has its own production standards. There are many types of hot melt adhesives and their bonding properties are different. According to the different speed of binding machine, glue different objects, open time, curing time, etc. to distinguish, choose to use adhesive and side glue.

The experience of using a hot melt adhesive index system for a printing company in North China can be used for reference. Their experience gained in practice: Strict quality inspection is required for every brand and lot of newly purchased hot-melt adhesives, and only qualified plastics for each indicator can enter the workshop. In this way, the quality of the bookbinding product is ensured. The quality indicators they control are mainly the following: 1 Low-temperature resistance indicators. They have designed a temperature-controlled freezer with a temperature error of +/-1°C and a temperature range of -10-10°C. The newly purchased hot melt adhesive is made into a certain strip and placed in a bending rack of a freezer, and a bending test is performed at a constant temperature of -1°C. After 30 minutes, no breakage is acceptable. They are embarking on the design of a hot-melt adhesive tester that can automatically control low-temperature resistance so that the measurement results are more objective and scientific. 2 anti-fatigue strength indicators. This is an indicator of the resistance to bending of the adhesive layer, which ensures that the book remains intact after multiple readings. First, the hot melt adhesive is made into a strip according to regulations, and then, a fatigue strength tester (homemade) at a prescribed temperature is tested to obtain a number of resistance to bending. 3 Specific indicators. After a comparative test, they found that the adhesive with a specific gravity greater than 1 had a lower overall performance than the hot melt adhesive with a specific gravity of less than 1. In addition, the greater the specific gravity of the hot melt adhesive, the greater the weight of the single-use adhesive when the adhesive layer is the same, which will significantly increase the production cost. The specific gravity can be measured according to the relevant adhesive measurement method. In practice, they often use the “float” method for qualitative determination: when the specific gravity is greater than 1, the adhesive will sink to the bottom, and the adhesive with the specific gravity less than 1 floats on the surface. This method is simple but fast and effective. 4 anti-aging indicators. The use of easy-aging hot-melt adhesives will obviously cause coking and discoloration in the process, which will inconvenience the normal operation of the process. Second, in the use of glue-booked books, due to the rapid aging of the glue, quality problems will occur. Affect the useful life of books. This indicator can be measured according to the national standard, but it takes longer. The simpler method is to treat the glue sample at a constant temperature at a higher temperature, and the change of the glue with poor aging resistance is very obvious.

"Good horses are equipped with good saddles." High-quality products must be backed by high-quality equipment and materials. Adhesive laminator, hot-melt adhesives, workshop temperature, humidity and other issues are directly related to the quality of glue-set products, so the work preparation before glue-binding is as follows:

1. The fixed-set workshop requires a normal operating temperature of 20°C to 30°C and a humidity of 50% to 70%. When glueing the product, preheat the hot melt adhesive 2 hours in advance. For older model plastic packers, there is another glue pot that does not have a hot melt preheater.
2. Data setting, specification and data review according to different specifications, different types of paper, book backs, thicknesses, etc. before rubber binding.
3, the choice of hot melt adhesive: To make the hot melt adhesive book pages do not loose pages, page off, it must make the book block between the staples must have sufficient tensile (fold) strength, we must use tensile strength High-temperature, small change in temperature, high melt viscosity, high hardness, tensile strength and elongation at break large hot melt adhesive.

The author believes that 80% of the glue-binding quality problems in production are caused by human factors such as improper operation and weak sense of responsibility. Operators must be familiar with the construction requirements of product process design and process flow, and must be responsible and responsible. Quality problems are guaranteed.