Discussion on the hottest plastic composites and t

2022-08-21
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Discussion on plastic composite materials and Technology (3)

other consumables of composite flexible packaging in addition to the above film materials, the other two materials used in the production process of flexible packaging are ink and composite glue

1. Composite ink products

composite ink is mainly divided into ordinary composite ink and high-temperature cooking ink according to its purpose; According to the material, it can be divided into polyamide ink, polyurethane ink and acrylic ink

2. Composite rubber products

(1) classification of composite rubber products

there are many kinds of composite rubber. It can be divided into single component glue, two-component glue for ordinary bags, two-component glue for boiled bags and high-temperature cooking glue according to its purpose. According to the system, it can be divided into polyurethane glue and acrylic glue. There are even more refined divisions, such as special glue for aluminum foil and special glue for aluminized film; According to the composition characteristics of adhesive, it can be divided into solvent-based adhesive, solvent-free adhesive and light curing adhesive

(2) market situation of composite adhesive products

in the domestic market, two-component polyurethane adhesive using ethyl acetate as solvent is still the mainstream product of composite adhesive. Polyurethane adhesive can be easily made into oligomer solution with high concentration and low viscosity, with strong molecular designability, ideal wetting performance for the surface of polymer, and high strength after curing. Because the polymerization technology is basically open and the threshold of intervention is low, there are many manufacturers and product brands, which can basically meet the needs of various production. In the domestic adhesive market for high-temperature cooking bag products, imported brands also occupy a considerable share

in addition, the two-component polyurethane adhesive has obvious disadvantages, such as high cost, large toxic pollution in the production process, unused glue to be discarded, and it is difficult to clean the roller

at present, one component rubber is developing rapidly. Because the requirements of many flexible packaging products are not high, the use of two-component glue has excessive performance and high cost. The use of one-component glue can solve this problem well. Once, some enterprises used toluene as solvent to make one-component composite adhesive, but the residual new round of scientific and technological revolution and industrial reform are ready to take place. Toluene pollutes the packaging, and its use is greatly limited. The alcohol soluble composite adhesive developed to solve this problem is a very ideal one-component adhesive. It is not only non-toxic, but also has excellent adhesion to BOPP film, pearlescent film, PE film, CPP film and other materials. The cost of using alcohol as solvent is relatively low

in the foreign market, solvent-free and UV curable adhesives have been relatively mature and are being promoted and applied in China, but their application in China is not plain sailing due to expensive equipment and harsh production conditions. At present, polyurethane adhesive is basically used in the market. Acrylic composite adhesive is a newly developed high-performance composite adhesive product

basic production process of composite membrane

the production of composite membrane is a typical dry composite process. The whole process is divided into five parts: preparation before recovery, gluing, drying, hot pressing and bonding, and curing. These five parts are introduced below

1. Preparation before resumption

this part of the work is often ignored by production workers, resulting in slightly higher energy consumption in lead smelting in blast furnace. However, the quality of products is often determined by this step. The contents of preparation before resumption mainly include

(1) membrane selection. Including the type, size and surface tension value of the film. According to the type of packaging bags to be produced, determine which facial mask, bottom film or intermediate film to use, and whether the tension value of the film surface is appropriate, and determine the corona treatment surface. These works must be carried out carefully

(2) preparation of glue. Since different bags need to use different adhesives, the type of adhesives and the approximate amount of glue should be determined according to the type and output of products, so as to avoid wrong or waste of details of Jinan spring testing machine industry classification

(3) equipment maintenance. Before starting production, the equipment must be in normal condition. Downtime in the production process is an important cause of loss and waste. In addition, the maintenance tools must be placed in the specified position to ensure that they can be accessed at any time

2。 Gluing

gluing is the most important section in the whole production process. The amount of glue determines whether the performance and cost of the product are in the best state

the existing equipment controls the gluing amount in different ways. The glue amount of the smooth roller is mainly controlled by the roller clearance. The amount of glue on the corrugated roller is jointly controlled by the number of lines, depth and drum clearance of the corrugated roller. In addition, the dilution ratio of glue solution is also an important parameter to control the amount of glue

generally speaking, the glue amount of ordinary ethylene propylene composite bags is about 2.2-2.6g/m2, that of boiled bags is about 2,8-3.5g/m2, and that of high-temperature cooking bags is about 3-4g/m2. In addition, the condition of the corrugated roller should be checked frequently. If there is blockage, it should be cleaned immediately with a special cleaning agent

in addition to the appropriate amount of glue, the uniformity of glue is also very important. It is necessary to carefully check whether the gap at both ends of the glue roller is consistent and whether the surface of the glue roller is clean. In a word, the rubber roller is in good condition, which can not only ensure the accuracy of the amount of glue, but also ensure the uniformity of glue

3. Drying

because the compound adhesive is made of ethyl acetate, which is switched back and forth as the solvent, the drying speed of the adhesive in the drying channel is very fast. However, the current equipment starts up very fast, and quality accidents caused by poor drying still occur from time to time. The main phenomenon caused by poor drying is that the composite film has more needle like white spots and the finished product has a strong smell

4. Hot pressing

hot pressing plays an important role in improving product quality. To. Generally speaking, on the premise of ensuring that the composite material will not be damaged, it is necessary to maintain a high roll temperature and rolling pressure as much as possible, so as to have good initial adhesion and transparency

5. Curing

curing is the process of providing certain temperature conditions for the two-component glue to complete the crosslinking reaction under static conditions. The fastness and transparency of the composite film are directly determined by the completion of this process. The curing condition is determined by the adhesive itself, and the product must be cured according to the parameters provided by the supplier

(to be continued)

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