Development of the hottest pvct type aluminized fi

Development of pvc-t type aluminized film

Abstract: This paper discusses the development process of pvc-t type aluminized film, and deeply discusses the key factors affecting the quality of aluminized film; The results show that the PVC coating film made of 5 resin can obtain pvc-t aluminum coating film with excellent fastness and brightness under appropriate aluminum plating process conditions

key words: PVC film aluminized coating

hard PVC film after vacuum aluminized not only has excellent kink performance, but also has moisture-proof, gas barrier and other barrier properties, as well as silver white appearance and brightness. It is widely used in high-end chocolate, candy, preserved meat, cakes and other packaging. With the continuous improvement of the quality requirements of the market, the requirements for the appearance brightness of PVC aluminized film and the firmness of aluminum layer are also continuously improved. For PVC aluminized film with poor firmness of aluminum layer, users should apply a layer of clear oil after printing to ensure that the printing layer will not fall off with the aluminum layer, which will increase the cost. Therefore, greatly improving the firmness of aluminum layer is an urgent requirement of the market, and it is also the key for PVC aluminum coating to adapt to the market and improve its competitiveness. In this study, a special layer of 5 resin was coated on the PVC substrate, and then vacuum aluminized after drying. The pvc-t type aluminized film [1] was obtained. The film has excellent firmness and brightness of the aluminized layer

1 experiment

1 1 raw material

pvc base film 25 μ m、28 μ m、30 μ m. It is made of PVC resin powder and various additives after kneading, extrusion and blow molding

1 ＃ resin, vinyl acetate content 15%, Germany

2 ＃ resin, glass transition temperature 70 ℃, Shenyang Sanhuan Fine Chemical Co., Ltd.

3 ＃ resin, glass transition temperature 105 ℃, Shenyang Sanhuan Fine Chemical Co., Ltd.

4 ＃ resin, 50 ± 2% solid content, Changzhou Guangming resin coating Co., Ltd.

5 ＃ resin, 49 ~ 61% solid content, Shanghai Xinhua resin factory

1.2 main equipment and instruments

Italian fiap blow molding unit

Italian fiap coating machine

Shanghai Shuguang Machinery Manufacturing Factory zz-1800k II vacuum aluminizing equipment

light transmittance instrument Italy

1.3 the process of developing pvc-t type aluminizing film is as follows [2] [3]

1.4 detection method of aluminum layer firmness

>adopt the enterprise standard "PVC aluminized film standard" (gt-qs-qc-171), the gradual construction of a multi-level patent protection system is divided into levels 1 to 5, with level 1 basically not dealuminated as the strongest and level 5 basically completely dealuminated as the worst

2 discussion of results

2.1 preparation of PVC base film

if the thickness of the base film deviates too much, it will cause difficulties in coating and aluminizing processes; If the film sinks, it will not only affect the next process, but also cause inaccurate chromaticity during printing; When there are water and oil stains on the film, the coating cannot be applied, which affects the fastness of aluminum plating, and will form spots on the aluminum plating film, making the aluminum plating film not bright. Therefore, when preparing PVC base film, we should focus on preventing these problems. After practical exploration, the treatment method is shown in Table 1, so as to prepare PVC base film with good thickness, no sinking, bright and clean

2.2 selection of coating materials

coating the same batch of PVC base film on the same coating roller at the speed of 80m/min. The optical properties of the coated light film are shown in Table 2, and the firmness of the aluminum layer after aluminum plating is shown in Table 3

it can be seen from table 2 that for 3 with large molecular weight, close the oil return valve and open the oil delivery valve to raise the platen. Due to poor solubility and transparency of resin, other materials are relatively transparent

it can be seen from table 3 that the firmness of aluminizing 1 resin as a coating is poor and it is not available. Other resins as coating materials, aluminum plating is solid, but due to the poor transparency of the light film after 3 resin coating. The brightness is not good after aluminizing, so it is not available. Therefore, 2 ＃, 4 ＃, 5 ＃ resins are optional materials. Since 2 resin is a solid, it needs to be dissolved and prepared in advance, and the batching process is more complicated, while 4 and 5 resins are concentrated liquids. Diluting with solvent is convenient for batching, so it is finally determined to use 4 and 5 resins as coating materials

2.3 quality control of coating process

the coating layer is not dry, which is easy to cause spots and white stripes; High air humidity and too much coating will cause the coating layer to whiten; Improper depth of the coating roller causes uneven coating and poor fastness of the aluminum layer

2.3.1 enhance the drying effect

when coating, on the premise of ensuring the hot air temperature of 60 ~ 70 ℃, increase the air volume as much as possible to improve the kinetic energy of solvent molecules in the coating, which is conducive to solvent volatilization; It turned out that the damper was always fully opened due to whitening after coating, and the drying effect was poor. After process adjustment, the semi closed damper was adopted to improve the drying efficiency. In order to better improve the drying effect, the hot drying channel of 3.5 meters was lengthened. Through the above measures, the drying effect is ensured, and the problems of dry and sticky coating and aluminum plating spots are eliminated

2.3.2 control of coating solution

coating roller is the key to control the coating amount and the coating quality. After comparing the coating roller made by Shanghai printing Research Institute and Beijing Xingdu, it is found that the roller made by Beijing Xingdu has better control of depth and number according to the design requirements, moderate coating amount and good coating quality. The solvent of the coating solution will volatilize in the coating tank and absorb heat at the same time, which will reduce the temperature of the tank wall and produce condensate, which will flow back into the coating solution, resulting in the whitening of the film after coating. Therefore, this problem is solved by compensating the temperature of the coating tank without condensate, and directly adding silica gel into the coating solution to absorb water directly

2.3.3 influence of air humidity

under the condition of high air humidity, the air used for drying contains too much water, which is not conducive to the volatilization of coating solvent, so that the drying effect is reduced, and even the coated film turns white, which is consistent with relevant studies [4], so it cannot be turned on when the humidity is greater than 80%

2.4 quality control of aluminizing process

to produce high-quality pvc-t aluminizing film, aluminizing process is a very important link. As the pvc-t-shaped film has a layer of thermoplastic resin coating, if the temperature is too high or the cooling is not good during aluminum plating, the coating will be deformed (its TG is very low) under the condition of stress and heating, and the surface finish will be damaged. After aluminum plating, refraction phenomenon will occur, resulting in rainbow phenomenon and "matte" of the aluminum plating film. Table 4 shows the changes of main roll cooling water temperature and "matte" under the condition that other aluminizing conditions remain unchanged

therefore, control the evaporation temperature (the lower the evaporation temperature without splashing, the better), evaporation capacity, tension (in order to stick to the cooling roller) and cooling water temperature, so as to control and eliminate the "matte" phenomenon and ensure the final quality requirements of pvc-t aluminized film

3 conclusion

(1) pvc-t aluminum plating film can be produced by using 4 and 5 resins as coating materials. The aluminum layer of the film has excellent firmness and brightness

(2) the quality control of PVC base film is the basis for the production of pvc-t aluminized film

(3) proper coating thickness control and drying are the key to ensure the firmness and brightness of pvc-t aluminum coating

(4) when aluminizing, low film temperature and no deformation of the coating are the key for pvc-t aluminizing film not to produce "matte"

Lin Yuanzhi

(Fuzhou Jiatong first plastic Co., Ltd.)

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