Development and application of the hottest water s

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R & D and application of water-soluble polyvinyl alcohol film (II)

4. Performance index

the main mechanical properties of water-soluble film can basically be determined by referring to other plastic films, but the performance parameters of water-soluble film as packaging have its particularity, such as water-soluble parameters

the main performance indicators of general water-soluble films include elongation, various strengths (tensile, heat sealing, tearing, etc.), equilibrium moisture under different relative humidity, heat sealing temperature, water-soluble effect, etc. These performance indexes are shown in Table 1 ~ Table 3 respectively

Table 1 main physical properties and test methods of water-soluble films

performance name unit data test method

fracture elongation and then unload the oil collector. Length%180 ~ 300 GB/t13022-91

tensile strength MPa 30 ~ 47 GB/t13022-91

heat sealing strength n/15mm 5 ~ 12 QB/t2358-1998

tear strength

Table 2 water solubility film at different relative humidity Degree equilibrium moisture and heat sealing temperature

project name (2) food producers purchase food related product parameters (value)

relative humidity 45 RH 65 RH 80 RH

equilibrium moisture 4 ~ 67-11 13 ~ 16

heat sealing temperature 170 ~ 200 150 180 140 ~ 170

Table 3 water solubility data of water-soluble films

name parameters (value)

water temperature advanced textile materials (℃) 253040

dissolution time (s) <300 45 ~ 50 25 ~ 30

among the listed performance indicators, table 1 is measured under the ambient temperature of 23 ℃ and relative humidity of 65%

RH, and table 3 is the results measured under normal temperature and pressure

III. application and expansion of soluble packaging materials

the biggest advantage of water-soluble film packaging materials is water solubility and barrier (also known as barrier). There are great technical difficulties in preparing water-soluble films from polyvinyl alcohol. At present, only a few countries such as Japan, the United States and France can produce, and China has just made progress in this regard

in the past, water-soluble films were hardly developed and applied in food packaging. The main reason is its sensitivity to water and humidity. Therefore, it is mainly used in the fields of pesticides, dyes, water treatment agents, mineral additives, pet cleaners, concrete additives, washing products and chemical fertilizers in the market. Its usage is to package pesticides in a packaging bag made of water-soluble film, put them into a container together with the packaging, add water to dissolve pesticides in water, and then stir them, and then work like usual spraying pesticides or fertilizing. Polyvinyl alcohol can reach 100% dissolution, and will not block the nozzle of agricultural appliances, nor affect the properties and efficacy of chemicals. When used as the packaging of washing products, such as detergent, it will bring great convenience, especially as a hospital or laundry service company, as long as dirty clothes (or bedding) and water-soluble film are packaged

the detergent is put into the washing machine for cleaning, which makes it more convenient for the staff to carry out cleaning services. The application of water-soluble film in food packaging is the result of the combination of modern packaging technology and modern life, which not only meets the requirements of lightweight. Many modern food packages use small packages, meal packaging (one meal consumption packaging) and one-time packaging. These packaged foods need to have matching large packages (bags, boxes, etc.). The function of large package is to seal and damp proof, while the small package in it is to provide convenience for consumption, use and treatment. Therefore, the application of water-soluble film in food packaging is the small package (bag) within the large package, such as the small bag packaging of soymilk, cereal, green tea, coffee and other foods, as well as the Dun packaging of small bag seasoning (ingredients in instant noodles). Small bag inner packaging will be a new field of application of water-soluble film

in addition, the application of water-soluble film in food packaging can be used as the film covering layer of food inner packaging (compounded with paper). After compounding with paper, the inner packaging made of paper will be easy to heat and seal, and it will not pollute the environment after being used up (it will dissolve in the rain in nature)

another application field of water-soluble films in the future will be the anti-counterfeiting and quality identification of food packaging. Water soluble films with different dissolution temperatures and dissolution times are prepared from saponified polyvinyl alcohol to be used as the packaging of non-aqueous liquids (such as emulsions, oily substances, etc.). Such substances are easy to be adulterated by criminals (adding water). After the authentic manufacturers use water-soluble film packaging, once the counterfeiters add water, the packaging will dissolve, so as to achieve the purpose of anti-counterfeiting and cracking down on counterfeits. In addition, many speculators harm consumers by injecting water into fresh meat on the market. We can use water-soluble film to identify it. Once fresh meat is injected with water, the water-soluble film will soften and dissolve

the application of water-soluble films in the field of food packaging has just begun, and more applications need to be further developed

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