C. Influence of temperature gradient in drying channel
Generally, the three temperature zones are set at 60 ℃, 70 ℃ and 80 ℃, but appropriate adjustment should be made according to the machine speed, glue amount and residual amount of methyl benzene under the printing film.
D. Influence of aircraft speed
The slower the machine speed is, the lower the residual solvent will be. However, it is necessary to prevent the too low machine speed, which will lead to too high heating temperature of the aluminum coating, resulting in the decrease of peeling strength.
E. The influence of benzol residue in printing
According to the statistics of the test data, if the residual amount of toluene solvent is high, the residual amount of ethyl acetate after compounding is relatively high, and generally it is 1.5-2 times higher. Therefore, after reducing the residual amount of toluene in printing process, the residual amount of ethyl acetate in the composite process will be reduced correspondingly.
F. Management of curing room
The curing room should be forced to ventilate. Generally, the primary air should be forced out in about 30 minutes. The composite membrane should be erected and not directly placed on the ground. The temperature fluctuation of the curing room should be as small as possible.
H. If it is found that the residual solvent exceeds the standard, it is very troublesome to deal with it
If it is a two-layer structure with poor barrier performance, such as BOPP / VMCPP,
BOPP / PE can be saved by drying and re drying. We used to make the products of BOPP / VMCPP structure solvent residual toluene: 5.44mg/m2, ethyl ester: 15.48mg/m2, after drying for two times, the residual solvent decreased to toluene: 2.01mg/m2, ethyl ester: 6.54mg/m2. But if it is a good barrier multi-layer structure, the residual solvent can only be scrapped.
4、 Representativeness and accuracy of sampling and testing
Even for the same sample, because of the different sampling methods, the residual value of solvent is very different, which requires that the sampling must be standardized and the method must be unified.
A. The sampling speed can not be reduced, so it must be online sampling. So it can represent the whole volume.
B. After sampling, it should be sealed in the aluminum foil bag without odor or glass bottle with rubber stopper immediately.
C. After opening the bag or bottle, the laboratory staff should carry out the test immediately and should not be placed in the air for a long time. Because the solvent of single film is easy to volatilize, but the whole film is difficult to volatilize.
D. The same sample should be made three times and the average value should be taken.
E. If the difference is too large, re sampling should be carried out.
F. The chromatograph shall be subject to aging test according to regulations.
G. In order to prevent data inaccuracy caused by instrument deviation, it is necessary to compare with the instruments of authoritative testing department or coating end user.
5、 Influence on the storage and transportation of finished products
A. After that, the finished product should be placed in a well ventilated environment for more than 24 hours.
B. The finished film should be packed with paper as far as possible, instead of waste printing film and waste composite film packaging, so as to facilitate air permeability.
C. After the bag products are out of the machine, air them for 4 hours, and then pack them after the heat is dissipated.
D. Don't tie the bag with rubber bands.
E. The paper core of finished product packaging should also be controlled, pulp and glue may produce odor.
F. The finished products are strictly prohibited to be stored in the same room with ink and thinner.
G. Ventilation is best during transportation.
H. The transport vehicles should be used for special purpose. Once, the packaging film was returned due to peculiar smell. However, the reason could not be found out in the company. Finally, it was found that the problem was found in the rented transport truck, and a batch of pesticide was transported on this vehicle, which was caused by leakage and odor due to lax packaging.
The above is our experience in production practice, for your reference only.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries.
We uphold the integrity of cooperation, good quality, good service business philosophy, won the industry's approval, products sold to all over the world; welcome friends from all walks of life to inquire, visit our factory to investigate guidance and business negotiations.