Talking about high temperature resistant cooking b

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Also on high temperature resistant cooking bags (IV)

4 Cast polypropylene CPP

in cooking bags, as the inner material that contacts the contents of food and can be heat sealed into bags, most of them are non stretched cast polypropylene films with a thickness of 70 μ m~80 μ m. Only a few use high-density polyethylene (HDPE) to manufacture bags with 121 ℃ from material development to simulated cooking

cpp has high chemical stability, can resist the corrosion of many media (such as acid, alkali, spicy, salty, oil, wine, aromatic spices, etc.), and is non-toxic, tasteless, extremely safe and hygienic. It can also be made into bags by heat sealing. It has better heat resistance than HDPE, and the maximum service temperature can reach 145 ℃

as CPP with high temperature cooking resistance, it should not be made of homopolypropylene, but should be made of CO polypropylene or polypropylene pellets modified by blending. This is required by the process conditions of high-temperature cooking of cooking bags. Because the CPP made of homopolypropylene will be brittle after high temperature cooking, the drop test is difficult to pass, and it is easy to crack at the seal, causing the contents to leak. The so-called co polypropylene is a copolymer containing about 5% ethylene or long chain alkene monomers, such as butene, octene and about 95% propylene. The so-called polypropylene modified by blending is made by blending ethylene propylene resin, polyisobutylene or rubber materials with homopolypropylene in a certain proportion. CPP film made of CO polypropylene or blending modified polypropylene has a soft feel, poor transparency than homopolypropylene, and large extensibility. When it is stretched under normal conditions or after high-temperature cooking, it shows strong toughness. There are metal plastic film blowing machine, machinery manufacturing industry uses high-tech luster silk, high sealing strength, and good pressure resistance and drop resistance. In the early 1980s, Shanghai could barely produce CPP with 121 ℃ high temperature cooking resistance by using j-230 polypropylene from Beijing Yanshan Petrochemical. In the early 1990s, Changzhou plastic factory launched CPP film specially for cooking bags, with better comprehensive performance than CPP made with j-230. At that time, CPP films were available in many places, but in addition to the limitation that the maximum service temperature was only 121 ℃, there were still shortcomings in the comprehensive performance. In recent years, Shanghai wisteria, Wuxi Huanya, Shanghai Meifeng, Hubei Jiangyu Zhongshan Zhongsheng and other products have such products, and the CPP provided by fosu group has good comprehensive performance in addition to high temperature cooking at 130 ℃ or even 135 ℃. At present, there are many manufacturers that can provide this kind of CPP film all over the country, and they have a wider range of choices. When we choose CPP, we should also pay attention to its surface tension. If it can be 40 ~ 42mn/m during compounding, it can be used safely. If it can be 39mn/m, it can also be used carefully, but if it is only 38mn/m or even lower, it cannot be used! This is very important

in recent years, the voice of high temperature cooking at 135 ℃ has become higher and higher, but there are not many CPPs that can really withstand this high temperature. The imported ones include ト -3701 from Japan's tosailu or xrc-18 from Japan's Mitsui products. Domestic CPP is still rare. After cooking at 135 ℃, many domestic CPP will be seriously brittle, with poor oil resistance, and even become mushy. Therefore, it is very important to choose suitable CPP if you want to make a cooking bag that can withstand 135 ℃

5. Other materials

materials that can be applied in cooking bags include PVDC with high barrier, PVA with high oxygen resistance, pen with high heat resistance and high barrier, special aromatic nylon MXD6, etc. in addition to PVDC, which has been applied by Henan Shuanghui group, due to the high supply and cost of membrane, it has not been really applied in cooking bags, but it does not rule out the possibility of real industrialization and commercialization in the future. Although the FDA did not prohibit the use of PVDC in food packaging, there was controversy, because fundamentally, its safety, hygiene and environmental protection were questioned

6. Adhesive

at present, most high temperature resistant cooking bags are made of the composite film produced by the dry composite method with the above substrate (film). There are three kinds of adhesives used in dry compounding, including polyurethane and modified polypropylene, namely aromatic polyurethane adhesive, aliphatic polyurethane adhesive and maleic anhydride modified polypropylene suspension adhesive (moprine)

from the development history of cooking bags, the earliest used adhesives are aromatic polyurethane synthesized with toluene diisocyanate (TDI) or diphenylmethane diisocyanate (MDI), such as imported ad502, eps901, uk3640, pp6260, A315, A520, pp3100, etc., and domestic ones include ly-9850, ly-9850r, ly-135a, uk2850, zs-9050, pu-1750, xy-z50e, xy-z50f, jp-1172, dib50a, yh502s, etc. However, since the FDA raised objections in the early 1980s, many companies have adopted more safe and reliable maleic anhydride modified polypropylene suspension adhesives or aliphatic polyurethane adhesives synthesized with HDI, XDI, IPDI, etc., such as domestic ly-9850f, imported ad1010c, ad506s, ad554, A505, pp5250, a515, a536, etc

according to the requirements of FDA, the adhesives used in high-temperature cooking bags are not allowed to contain aromatic polyurethane. Because the residual monomers in this kind of glue may produce "fragments" of cracking during high-temperature cooking, and will migrate to the packaged contents to produce aromatic amines (TDA or MDA) with moderate carcinogenic effect, which is harmful to the health of consumers. Therefore, FDA only agrees to use modified polypropylene and aliphatic polyurethane adhesives to manufacture high-temperature cooking bags. If the packaged cooked food is to be sold to North America, or later to Europe, aromatic polyurethane should not be used to avoid unnecessary trouble and major economic losses. I personally believe that, fundamentally speaking, even cooked food exported to Southeast Asia or Japan, or cooked food sold only in China, should not be packaged in composite bags made of aromatic polyurethane glue, and it is best to use bags made of aliphatic polyurethane glue. This is the real people-oriented and equal treatment

adhesives for high-temperature cooking must have good bonding fastness and heat resistance. At the same time, adhesives of different brands and models should be selected according to different substrates and temperature resistance grades. Some models of glue are only applicable to plastic/plastic cooking bags, not aluminum/plastic cooking bags. Some models can only withstand 120 ℃, while others can withstand 128 ℃, some can withstand 135 ℃ or even 145 ℃, some can only cook for 30min, some can cook for 40min, 60min, or even 120min. After high temperature cooking, the peeling power of cooking glue with good performance will be reduced little, or not reduced, or even increased. This kind of glue has strong adaptability and wide applications. Of course, from the perspective of cost performance, due to its high technical content, special raw and auxiliary materials, and relatively high price, we must choose it appropriately

as people pay more and more attention to the safety and health of food and food packaging materials, and the state monitors it more and more strictly, when we choose adhesives, we must pay attention to the safety and health inspection of the product, see which level of unit is responsible for the inspection, and see what its LD50 or MTD value is, See if it has done the potential toxicity test according to gb15193 safety toxicology evaluation procedures and methods. If the LD50 or MTD value is greater than 15000mg/kg body weight, reaching the "non-toxic level" of the highest safety level, and has also done the tests of Hematology, biochemistry, histology, teratogenicity, carcinogenesis, mutagenicity and genotoxicity to prove that it is safe and reliable, then this adhesive is a good adhesive that can be used safely. Now we are advocating safe and reassuring food, which should be guaranteed by the whole chain formed by reassuring agricultural and sideline products, reassuring additives, reassuring processing process and reassuring packaging materials. No link can be neglected, so we can't be careless

7. Ink

at present, most of the high-temperature cooking bags are non printed "white bags" or simply printed bags, and rarely multiple sets of beautifully printed products. If it is a white bag, then put an ordinary multi-color printing opp/pe composite bag after cooking, which turns into a situation of two bags packaging one bag of food, resulting in an increase in packaging costs. According to the regulations, all food packaging bags (objects) should at least be printed with the name of the factory, address, ingredients, production date, shelf life, edible precautions and other main contents. The oil pipe on the host is connected with the electric control cabinet. Therefore, if they are printed on the cooking bag, high temperature cooking oil ink is indispensable

ordinary inks do not have heat resistance. After cooking, they will separate layers, and some colors will change or fade. Therefore, the binder of high-temperature cooking inks should not be surface printing inks or ordinary internal printing inks, but two-component polyurethane that can withstand high temperature, and its pigments or dyes must be able to withstand high temperature without discoloration and fading

at present, many ink factories in China can provide high-temperature cooking resistant inks. In addition to foreign-funded technology products such as shenri, Shanghai DIC, Jiangmen Toyo, Tianjin Toyo, etc., pure domestic products that change the position of the active needle at any time during use have also been applied, such as super Lifu 300lm, 314, and wx-01. Ye's "Bauhinia" brand also has cooking resistant composite inks for us to choose from

a good high temperature resistant cooking ink should be an ink with two-component reactive polyurethane as binder. Like two-component PU adhesive, it packages colorless curing agent and various color inks separately. Due to different manufacturers, the proportion and dosage of color ink and curing agent are not exactly the same, about 100:5 ~ 100:10, that is, 5kg to 10kg of curing agent should be added for every 100kg of color ink. After being fully stirred and diluted to the appropriate viscosity, it can be printed on the machine. The advantage of two-component ink is that it has good printing fastness and can get satisfactory results on pet or OPA film. After crosslinking and curing, the ink layer can withstand high temperature and form a strong adhesion with the composite adhesive. However, the remaining inks will slowly crosslink and solidify, and lose printability. Therefore, it often causes waste and high cost, which requires us to pay attention to the preparation of the amount of ink used. We should pay more attention to the preparation of more consumed ink, more consumed ink, less consumed ink, more used ink, and not too much at once

8. Solvent

solvents are used in composite adhesives and printing inks when manufacturing high-temperature cooking bags. Due to the high quality requirements of cooking bags, special care must be taken with the solvents used

first of all, the composite glue and ink used in the high-temperature cooking bag are expected to be manufactured with high-quality and high-purity non-toxic, tasteless, odorless and residue free solvents, and should not contain benzene, toluene, xylene, cyclohexanone or other high boiling point solvents. Secondly, in addition to the above requirements, the dilution solvent used in mixing glue and ink should also have strict standards for the amount of water content, because the existence of water will have a very adverse impact on the use effect of glue and ink. The water content of the solvent required for dilution varies from urethane grade to below 300ppm (i.e. 0.03%) in the products of various suppliers. However, from the perspective of industrial production, this is very harsh. When we choose adhesives and inks, it is best to avoid delicate products and adopt strong products. The kind of adhesive that can meet the requirements with ethyl acetate (measured water content less than 0.2%) of industrial grade I products that are easy to purchase, sufficient supply and low price should be the preferred product. that

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