Characteristics of the hottest solvent-free compos

2022-08-17
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Solvent free compounding process characteristics and material selection

the commonly used film compounding technologies include dry compounding, extrusion compounding, wet compounding, hot melt adhesive compounding, etc. At present, dry compounding and extrusion compounding have the largest output and the widest application in China. Dry compounding is widely used because it has many kinds of substrates, high bonding strength, flexible variety exchange, and the composite film can have the properties of cooking resistance, high barrier, low temperature resistance and so on. However, the dry compounding technology of thin films uses solvent based adhesives, which has the disadvantages of large floor space, large energy consumption, solvent pollution in the production process and so on

governments around the world pay more attention to environmental pollution. Many countries have promulgated strict regulations to limit the pollution of solvent volatilization to the atmosphere. In view of the problem of solvent volatilization pollution caused by film packaging materials in the compounding process, people continue to develop new technologies and processes, and solvent-free compounding technology, as a safe film compounding technology that replaces solvent-based adhesives, is developing steadily. More and more manufacturers of packaging materials in the world tend to adopt solvent-free composite technology in order to eliminate the pollution caused by solvent volatilization. It can complete the experiments of simply supported beam and cantilever beam

first, the characteristics of solvent-free composite process

using solvent-free composite process to manufacture composite film packaging materials has now become a mature application technology. At present, it has occupied a very important position in the European and American markets. Compared with the dry solvent compounding process, it has the following advantages:

1. Solvent free compounding can significantly reduce the production cost of composite films compared with dry compounding. The main reason can be summarized as follows: the production performance of solvent-free compounding equipment is the same as that of solvent-based or water-based compounding equipment, but the solvent-free compounding equipment has no pre drying oven, In order to install the stretching fixture, the structure is compact, the occupied space is small, the equipment cost is low, and the one-time investment is small; Therefore, the investment in equipment is much lower. Therefore, the comprehensive cost is low

2. The adhesive used for solvent-free compounding does not contain any solvent, so in the production process, there is no solvent emission, and there is almost no production of three wastes, which will not affect the health of production workers and avoid environmental pollution. It is conducive to cleaner production. Good adaptability to environmental protection,

3. In solvent-free composite production, the deformation and elongation of the sample in the tensile test are not only due to the use of adhesives containing flammable and explosive organic solvents within the marking line, so the safety is good, and special fire and explosion-proof measures are not required in the factory and production workshop; Fire and explosion hazards can be minimized

4. the structure of the equipment is compact, and the number of operators is less than that of dry compounding, which reduces the personnel cost. High production efficiency

5. The equipment consumes less energy. Compared with other compounding machines, solvent-free compounding equipment has no drying oven, which reduces energy consumption. The energy consumption of the equipment has been greatly reduced. At the same time, the longer drying oven for the solvent in the volatile adhesive is eliminated, thereby eliminating the problem of material curling. Materials have a short journey on the equipment, which can reduce waste

6. the amount of solvent-free adhesive on the unit area of the film is small, which is generally controlled at 1 2G/m2, and the glue amount of solvent adhesive is 5g/m2, so the cost of solvent-free composite adhesive per unit area is lower than that of dry composite adhesive. Therefore, the production cost of composite products per square meter is low

7. the compounding speed is fast, the production efficiency of the equipment is high, and the production speed can reach M/min. The maximum production speed is up to 480m/Min, generally 200m/Min or so

8. The adhesive used for solvent-free compounding does not contain solvents, so the final composite film product does not contain the contents of the package polluted by the presence of residual solvents; It is more suitable for the packaging of food commodities that are very sensitive to smell. The composite film adopts internal printing, so the ink pattern on the printing surface will not be affected by the solvent and the quality will not decline; When compounding, the substrate will not be deformed due to the heating of solvent and drying channel, so that the flatness of the composite film will be reduced, and the dimensional stability of the composite film structure will be good. In addition, the solvent-free compounding equipment is equipped with corona treatment unit, which has good compounding performance for films with corona extinction and high lubricant content. Therefore, the product quality is easy to be guaranteed

9. nowadays, the solvent based composite process has been applied to the printing equipment on-line, but due to the high residual solvent, the residual solvent needs to be removed in time, which restricts the production speed of the equipment. On the contrary, the production efficiency of solvent-free compounding machine connected with printing machine is 50% higher than that of solvent-based or water-based compounding machine connected with printing machine

disadvantages of solvent-free compounding process:

1. It can't be applied to standard solvent compounding equipment, so it needs to reinvest solvent-free compounding equipment, and the coating system is complex, and it needs heating devices

2. The initial viscosity of the composite product is low and the curing time is long

3. The glue has high viscosity and short storage time after mixing

4. The tension system of composite equipment requires high accuracy, and the operation level of operators should be fast, convenient and cost-effective

5. The flatness and thickness of the composite substrate are strictly required, and the surface tension of the film is large

6. The composite strength decreases obviously with time

7. When compounding some packaging products with high quality requirements (pesticide bags, high temperature cooking bags, etc.), their performance and compounding quality cannot reach the level of solvent based polyurethane adhesive

(to be continued)

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