The explanation of PE is as follows: 1. = Prince Edward Island 2. = price earthings stock return 3. = physical education sports 4. = polyethylene, but in your case, it means "polyethylene"! The sanitary plastics of plastics and their products are a kind of high molecular compound. The plastic products are made of synthetic resin as the main raw material, adding some additives such as plasticizer, stabilizer, antioxidant, etc. under certain plasticizing conditions. At present, the allowable food containers, packaging materials and the thermoplastics used in the manufacture of food tools and equipment in China include polyethylene, polypropylene, polyvinyl chloride, vinylidene chloride, polycarbonate, polyethylene terephthalate, nylon, unsaturated polyester resin, acrylonitrile styrene copolymer resin, re acrylonitrile styrene copolymer resin, acrylonitrile butadiene styrene copolymer resin. The thermosetting plastics include melamine formaldehyde resin, etc. ? 1. Physical and chemical properties of polyethylene (PE) and polypropylene (PP)? 1. Polyethylene and polypropylene are polymerized with ethylene and propylene as monomers. Molecular formula of polyethylene: molecular weight: molecular formula of polypropylene: molecular weight: about 100000-500000? According to the pressure during polymerization, polyethylene plastic is divided into high-pressure polyethylene or low-density polyethylene (LDPE) and low-pressure polyethylene or high-density polyethylene (HDPE). High pressure polyethylene is mainly used in the manufacture of food plastic bags, fresh-keeping films, etc.; low pressure polyethylene is mainly used in the manufacture of food plastic containers, pipes, cutting boards, etc. Polypropylene plastic film can be stretched longitudinally and transversely to change its mechanical properties and increase its strength and transparency. According to the stretching direction, polypropylene plastic film is mainly used to make food plastic bags, especially composite plastic bags; polypropylene can also be processed into food containers that are both resistant to low temperature and high temperature, such as preservation boxes and containers for microwave ovens. ? 2. Main health problems: the toxicity of polyethylene and polypropylene resin is very low, and kd50 is greater than the maximum possible dose. Because of its long saturated straight chain alkane, it has high chemical stability and low biological activity. There is no obvious toxic effect in oral subacute and chronic tests, teratogenic and carcinogenic tests. The content of ethylene and propylene monomers in polyethylene and polypropylene resin is very small, and the toxicity of ethylene and propylene itself is also low. In the production of polyethylene and polypropylene resin and molding products, agents are rarely used. Therefore, polyethylene and polypropylene plastics are relatively safe plastics, which can be widely used as food containers and packaging materials, but low molecular weight polyethylene is easy to dissolve in oil, so the tableware made of polyethylene should not be filled with edible oil regularly to avoid the smell of oil. According to GB 9691-88 hygienic standard for polyethylene resin used in food packaging, GB9687-88 hygienic standard for polyethylene molding products used in food packaging, gb9693-88 hygienic standard for polypropylene resin used in food packaging and gb9688-88 hygienic standard for polypropylene molding products used in food packaging, both resin and molding products need to control free monomer. ?　　The explanation of PE is as follows: 1. = Prince Edward Island 2. = price earthings stock return 3. = physical education sports 4. = polyethylene, but in your case, it means "polyethylene"! The sanitary plastics of plastics and their products are a kind of high molecular compound. The plastic products are made of synthetic resin as the main raw material, adding some additives such as plasticizer, stabilizer, antioxidant, etc. under certain plasticizing conditions. At present, the allowable food containers, packaging materials and the thermoplastics used in the manufacture of food tools and equipment in China include polyethylene, polypropylene, polyvinyl chloride, vinylidene chloride, polycarbonate, polyethylene terephthalate, nylon, unsaturated polyester resin, acrylonitrile styrene copolymer resin, re acrylonitrile styrene copolymer resin, acrylonitrile butadiene styrene copolymer resin. The thermosetting plastics include melamine formaldehyde resin, etc. ? 1. Physical and chemical properties of polyethylene (PE) and polypropylene (PP)? 1. Polyethylene and polypropylene are polymerized with ethylene and propylene as monomers. Molecular formula of polyethylene: molecular weight: molecular formula of polypropylene: molecular weight: about 100000-500000? According to the pressure during polymerization, polyethylene plastic is divided into high-pressure polyethylene or low-density polyethylene (LDPE) and low-pressure polyethylene or high-density polyethylene (HDPE). High pressure polyethylene is mainly used in the manufacture of food plastic bags, fresh-keeping films, etc.; low pressure polyethylene is mainly used in the manufacture of food plastic containers, pipes, cutting boards, etc. Polypropylene plastic film can be stretched longitudinally and transversely to change its mechanical properties and increase its strength and transparency. According to the stretching direction, polypropylene plastic film is mainly used to make food plastic bags, especially composite plastic bags; polypropylene can also be processed into food containers that are both resistant to low temperature and high temperature, such as preservation boxes and containers for microwave ovens. ? 2. Main health problems: the toxicity of polyethylene and polypropylene resin is very low, and kd50 is greater than the maximum possible dose. Because of its long saturated straight chain alkane, it has high chemical stability and low biological activity. There is no obvious toxic effect in oral subacute and chronic tests, teratogenic and carcinogenic tests. The content of ethylene and propylene monomers in polyethylene and polypropylene resin is very small, and the toxicity of ethylene and propylene itself is also low. In the production of polyethylene and polypropylene resin and molding products, agents are rarely used. Therefore, polyethylene and polypropylene plastics are relatively safe plastics, which can be widely used as food containers and packaging materials, but low molecular weight polyethylene is easy to dissolve in oil, so the tableware made of polyethylene should not be filled with edible oil regularly to avoid the smell of oil. According to GB 9691-88 hygienic standard for polyethylene resin used in food packaging, GB9687-88 hygienic standard for polyethylene molding products used in food packaging, gb9693-88 hygienic standard for polypropylene resin used in food packaging and gb9688-88 hygienic standard for polypropylene molding products used in food packaging, both resin and molding products need to control free monomer. ?　(5) polycarbonate (PC)? 1. Physical and chemical properties: polycarbonate is a general term for a class of high molecular compounds containing carbonate in the molecular chain. According to the type of R group, polycarbonates can be divided into aliphatic, alicyclic, aromatic and aliphatic aromatic groups. At present, only bisphenol-a-type aromatic polycarbonate resin is made from bisphenol-A and diphenyl carbonate by transesterification and polycondensation. Its molecular formula is: polycarbonate is a kind of thermoplastic engineering plastics with heat resistance, cold resistance and good mechanical properties. Due to its tasteless, oil-resistant and pollution-resistant characteristics, polycarbonate resin is mainly used in the manufacture and processing of horizontal utensils (such as biscuits, gongkeli molds, etc.), baby bottles, food processing machinery and other food containers and food processing equipment with impact resistance and certain transparency requirements. ? 2. Main health problems: polycarbonate resin itself is non-toxic, oral LD50 is > 10g / kg body weight, and mutagenicity test (a, ES test, micronucleus test and sperm malformation test) is negative. However, when bisphenol A is transesterified with diphenyl carbonate, the intermediate phenol is produced. Phenol not only has certain toxicity, but also produces heterosmell, which affects the sensory properties of food. The weight and tensile strength of polycarbonate resin decreased significantly after 30 days soaking in 50% and 100% glycol solution. Therefore, according to gb13116-9 1 hygienic standard for polycarbonate molding products for food containers and packaging materials, the content of free phenol in polycarbonate resin for food containers and packaging materials and molding products should be controlled below 0.05mg/l, and should not be exposed to high concentration ethanol solution. ? (6) polyethylene terephthalate (PET)? 1. Physical and chemical characteristics: polyethylene terephthalate resin is made of terephthalic acid and glycol as raw materials, which are transesterified to form terephthalic acid bis (β - hydroxyethylene) monomer, and then self condensed. The molecular formula is:??? Polyethylene terephthalate (commonly known as polyester) has good physical and mechanical properties such as high strength and toughness, high resistance gas, high transparency, and is acid, alkali, solvent and heat resistant (film). Therefore, polyethylene terephthalate is mainly used to make films (as raw materials of composite food packaging bags), beverage bottles with or without carbon dioxide, oil bottles and other condiment bottles. ? 2. Main health problems: polyethylene terephthalate resin is nontoxic, LD50 of resin or extract is more than 10 g / kg, and mutagenicity test (Ames test, micronucleus test and sperm malformation test) is negative. Due to the use of antimony (generally antimony trioxide or antimony acetate) as catalyst in the self polycondensation of polyethylene terephthalate resin, there may be residual antimony in the resin. Antimony is a medium acute toxic metal. The LD50 (abdominal cavity) of antimony trioxide rats is 3.25g/kg body weight, and the rats are fed with 100mg / kg dose for 12 months, which can damage the myocardium. Germanium is also used as a catalyst abroad. Therefore, according to gb1314-91 hygienic standard for polyethylene terephthalate molding products for food containers and packaging materials, the content of antimony in polyethylene terephthalate resin for food containers and packaging materials and molding products should be controlled below 1.5mg/kg and 0.05mg/l respectively. ? (VII) polyamide (nylon mylon)? 1. Physical and chemical properties: polyamide is a kind of high molecular compound with many repeated amide groups in the main chain, usually named nylon. Nylon can be made by polycondensation of diamine and dicarboxylic acid, or it can be made by self polycondensation of a kind of lactam. There are many kinds of nylon. The name of nylon made by condensation of diamine and dicarboxylic acid is determined by the number of carbon atoms in diamine and dicarboxylic acid. For example, the polycondensate made by reaction of hexamine and sebacic acid is nylon 610; the polycondensate made by self condensation of lactam is nylon 6. Therefore, there are two general types of nylon:??? Nylon has the characteristics of wear resistance, heat resistance, cold resistance, drug resistance, strength and toughness, but its acid resistance is poor. Therefore, nylon is mainly used to make film (as raw material of composite food packaging bag), filter screen and food processing machinery. ? 2. Main health problems: Nylon itself is non-toxic, and the immersion solution of nylon 6 resin has an oral LD50 > 10g / kg body weight in mice, and the mutagenicity test (Ames test and micronucleus test) is negative. However, nylon 6 contains caprolactam. It has been reported that long-term intake of caprolactam can cause neurasthenia. Therefore, according to gb16331-96 hygienic standard for nylon 6 resin used in food packaging materials, gb16332-96 hygienic standard for nylon 6 resin used in food packaging materials and gb16332-96 hygienic standard for nylon molding products used in food packaging materials, the residual amount of caprolactam in nylon 6 resin used in food containers, packaging materials and molding products shall be controlled below 150mg / L and 15mg / L respectively. ?　(VIII) unsaturated polyester resin and its glass fiber reinforced plastics 1. Physical and chemical properties: the liquid unsaturated polyester resin is made by adding styrene to the polyester produced by unsaturated polyester resin with polyol, unsaturated dicarboxylic anhydride and saturated dicarboxylic anhydride as the main raw materials under the action of initiator and maintenance agent. The unsaturated polyester resin products made of glass fiber are called glass fiber reinforced plastics. FRP has the characteristics of easy forming, cold resistance, light weight and impact resistance. Therefore, unsaturated polyester and its glass fiber reinforced plastics are mainly used to make frozen fish storage plates, wine and seasoning fermentation tanks, refrigerators and water tank storage plates, etc. ? 2. Main health problems: unsaturated polyester resin and its glass fiber reinforced plastics are non-toxic. The oral LD50 of unsaturated polyester resin is more than 15 kg / kg body weight, and the mutagenicity test (Ames test, micronucleus test and sperm malformation test) is negative. However, initiator and catalyst are needed in the polymerization and curing of UPR and FRP. Therefore, there will be residues of initiator and catalyst in UPR and FRP. There are many kinds of initiators and catalysts, some of which are toxic. Gb9685-94 hygienic standard for the use of additives for food containers and packaging materials stipulates that the unsaturated polyester resin and its glass fiber reinforced plastics for food containers and packaging materials shall use MEK peroxide as the initiator and cobalt naphthenate as the catalyst. In addition, styrene is not only the solvent of unsaturated polyester resin and its FRP, but also the curing crosslinker. Therefore, styrene residue is inevitable. Ethylbenzene is often mixed in styrene. Styrene has great toxicity. The residue of styrene is related to the ratio of initiator and catalyst, the formula, the degree of curing and the treatment of molding. According to gb13115-91 hygienic standard for unsaturated polyester tree finger and fiberglass reinforced plastics for food containers and packaging materials, the content of ethylbenzene compounds (calculated by styrene) in the unsaturated polyester resin template and fiberglass reinforced plastics for food containers and packaging materials shall be controlled below 0.2% and 0.1% respectively. ? (IX) PVDC? 1. Physical and chemical properties: PVDC is polymerized from vinylidene chloride monomer. ? molecular formula:??? Molecular weight: about 20000-100000. ? polyvinylidene chloride has excellent moisture resistance and air tightness, stable chemical properties, good chemical resistance, and heat shrinkage. But the price is expensive and the heat sealing performance is poor. Polyvinylidene residues. Vinylidene chloride is a kind of medium toxic substance, which has very weak accumulation and no mutagenicity. Therefore, gb15204-94 hygienic standard for vinylidene chloride vinyl chloride copolymer resin for food containers and packaging materials stipulates that vinylidene chloride and vinylidene chloride residues are lower than 10mg / kg and 2mg / kg respectively. In addition, PVDC film used as casing is often added with red colorant. Migration of colorants into food is also a problem that cannot be ignored. ? (x) acrylonitrile styrene (as) and acrylonitrile butadiene styrene (ABS) copolymer resins? 1. Physical and chemical characteristics: acrylonitrile styrene resin is formed by copolymerization of acrylonitrile and styrene. Acrylonitrile butadiene styrene resin is composed of polybutadiene, styrene butadiene rubber or rubber rubber rubber, which is dispersed in glass polymer of acrylonitrile styrene or polystyrene, and polymerized by mixing, grafting or grafting. ? molecular formula of acrylonitrile styrene:? Molecular formula of acrylonitrile butadiene styrene:? Acrylonitrile styrene resin and acrylonitrile butadiene styrene resin are thermoplastic engineering plastics. It not only maintains the luster of polystyrene, processing fluidity and corrosion resistance, but also has the impact resistance of rubber. Acrylonitrile styrene resin also has heat resistance and transparency. Therefore, acrylonitrile styrene and acrylonitrile butadiene styrene plastics are mainly used to manufacture industrial and household food processing equipment and machinery, as well as refrigerator liners, fruit and vegetable boxes, pipes, etc. ? 2. Main health problems: acrylonitrile styrene resin and acrylonitrile butadiene styrene resin are non-toxic. However, both of them contain acrylonitrile monomer, and acrylonitrile is more toxic. The LD50 of oral fat was 25-186mg / kg body weight, which could also cause loss of system, kidney damage and blood biochemical changes. Chronic animal experiments have proved that it can damage the kidney, brain, kidney and even cause tumor. Moreover, acrylonitrile in the resin will migrate to the food, and the migration amount has a significant linear correlation with the residual amount. Therefore, the hygienic standards for acrylonitrile styrene molding products and acrylonitrile butadiene styrene molding products for food containers and packaging materials stipulate that the dissolution of acrylonitrile is less than 50mg / kg and 11mg / kg respectively.