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    Home > API > Hormones and the Endocrine System > Polyvinyl Alcohol (PVA)
    Polyvinyl Alcohol (PVA) structure

    Polyvinyl Alcohol (PVA)

    • CAS No:

      9002-89-5

    • Formula:

      C2H4O

    • Synonyms:

      Poly (1-Hydroxyethylene); Poly (Vinyl Alcohol);

    • China Export:

      From 2018.11 to 2019.11, total export volume of Polyvinyl Alcohol (PVA) from China was 170,067,311KG while total export value was $298,497,800. The biggest proportion of exporting volume in the last 12 months was 9.75% in 2019.07.

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    Description

    Polyvinyl alcohol is a hydrolysis product of polyvinyl acetate, rather than by the polymerization of monomers; the molecular backbone contains
    . The specific gravity of this product 1.25 to 1.35 and the melting point is 212 ~ 267 ℃. It is soluble in hot water and hot dimethyl sulfoxide. Animal experiments show that polyvinyl alcohol, without stimulation, causes no significant toxicity upon subcutaneous, intramuscular, intravenous injection. Polyvinyl alcohol resin products appear as white

    Basic Attributes

    • 9002-89-5

    • C2H4O

    • 44.05260

    • 44.02620

    • 20.23000

    • 0.6879

    Characteristics

    • White or cream colored solid

    • 1.3

    • 230-240ºC

    • 23.5ºC at 760 mmHg

    • 79ºC

    • 1.381

    • soluble in hot water

    • Polyvinyl alcohol is stable when stored in a tightly sealed container in a cool, dry place. Aqueous solutions are stable in corrosionresistant sealed containers. Preservatives may be added to the solution if extended storage is required. Polyvinyl alcohol undergoes slow degradation at 100°C and rapid degradation at 200°C; it is stable on exposure to light.

    • Stable. Combustible. Dust may form explosive mixtures with air. Incompatible with strong oxidizing agents.

    Safety Information

    • 3905300000

    • NONH for all modes of transport

    • 1

    • R23/24/25; R36/38; R39/23/24/25

    • S24/25

    • TR8100000

    • Xn

    • P260

    • H371

    • LD50 orally in Rabbit: > 20000 mg/kg

    Product Usage

    Used in chemical industry, textile, printing, paper making, leather making, agriculture, food, medicine, packaging, ceramics, electronics, makeup, construction and other industries. Mainly used as binder, textile auxiliary, paper auxiliary, cement additive, emulsifier, dispersant, etc. Adding water-soluble PVA to putty powder can improve the adhesion and prevent cracking and powder loss. It can be used as an emulsion stabilizer for emulsion polymerization of polyvinyl acetate. Used to make water-soluble adhesives. Used as a modifier of starch adhesives. It can also be used to prepare photosensitive adhesive and benzene solvent-resistant sealant. Also used as release agent, dispersant, etc.

    Production Methods

    (1) The preparation of polyvinyl acetate Industrial use of bulk, solution, suspension, emulsion polymerization of four polymerization methods to produce polyvinyl acetate. Since the reaction temperature of the solution polymerization is easily controlled and the number of polymer branches is small, the polyvinyl acetate methanol solution obtained after the polymerization can be directly subjected to alcoholysis to prepare polyvinyl alcohol. Therefore, the solution polymerization of polyvinyl acetate in the synthetic fiber industry is widely used. The process of continuous solution polymerization of vinyl acetate is as follows: the polymerization system is replaced with nitrogen gas before feeding, so that the oxygen content is less than 1%. The initiator azobisisobutyronitrile dissolved in methanol dubbed (1.3 ± 0.5)% methanol solution. And then refined vinyl acetate, methanol and initiator methanol solution, etc. mixed material into the preheater, the material preheated to 59 ℃ to remove dissolved oxygen. The preheated material enters the first-stage reactor, the reaction temperature is 60-65 DEGC, the material is continuously added, the average residence time is 2 to 3 hours, and the polymerization rate is about 20%. And then into the second-stage reactor to continue polymerization, the material in the second reactor average residence time of about 3h, polymerization rate of 50% to 60%. After the completion of the reaction, the unreacted monomers were blown out with methanol vapor, and the polyvinyl acetate after demethylation was diluted with methanol to a concentration of 20% to 22% and sent to the alcoholysis step. (2) Ethanolysis of polyvinyl acetate The polyvinyl acetate methanol solution prepared above was continuously fed into a twin-screw alcoholysis machine while adding a certain ratio (the molar ratio of polyvinyl acetate to sodium hydroxide was 1: 0.12), and the alcoholysis temperature is 45-50 ° C. The resulting polyvinyl alcohol is sponge-like precipitated by insolubilization in methanol, and the saponified waste liquid is extruded through a screw extruder. The sponge-like polyvinyl alcohol is washed with water several times, and then vacuum-dried at 80 ° C and heat-set Processing that was finished. (3) First, polyvinyl acetate is prepared by solution polymerization, and then the prepared polyvinyl acetate is hydrolyzed rapidly in the mixture of methanol, ethanol or ethanol and methyl acetate with alkali metal or acid-free catalyst. And alcoholysis was carried out to obtain polyvinyl alcohol. (4) The preparation method Filtration of 6% KOH-C2H5OH solution temperature is controlled at 20 ~ 25 ℃, stirring slowly adding 26% of the polyvinyl acetate solution to control the dropping rate to prevent agglomeration jelly, feeding After the completion of the maintenance of 20 ~ 25 ℃ 2h, and then cooled to room temperature, filtration, the resulting white light yellow solid, with a small amount of 70% ethanol washing several times, drained and dried under vacuum 50 ~ 60 ℃, . 5. The production process of polyvinyl alcohol according to the raw material is divided into two types of ethylene and acetylene. International production of PVA process line to dominate the ethylene method, the number of the total production capacity of 72%. Its processes include: the acquisition of ethylene and vinyl acetate synthesis, distillation, polymerization, polyvinyl acetate (PVAc) alcoholysis, acetic acid and methanol recovery of the five processes. Acetylene synthesis according to its different sources of raw materials can be divided into calcium carbide acetylene synthesis and natural gas cracking acetylene synthesis. Carbide acetylene synthesis, the earliest industrial production. As a result of this process line products, high energy consumption, low quality, high cost, the production process impurities are more serious environmental pollution, lack of market competitiveness, is gradually phasing out. Natural gas, coal and electricity-rich areas, natural gas acetylene synthesis is still a direct method of vitality. The polymerization of vinyl acetate is as follows: After preheating, vinyl acetate is mixed with solvent methanol and initiator azobisisobutyronitrile and fed into two series polymerization vessels. Polymerization is carried out at 66-68 ° C and atmospheric pressure. Polymer 4 ~ 6H, about 2/3 of vinyl acetate polymerization of polyvinyl acetate. The heat generated by the polymerization reaction can be taken away by the evaporation of methanol, which is condensed and returned to the polymerization vessel. The polymerized monomer was blown out of the column, and the unreacted vinyl acetate was blown out with methanol vapor. From the monomer blowing out of the tower by the separation of vinyl acetate and methanol distillation, recycling recycling. The polymerization solution was methanol-adjusted to a methanol solution with 33% polyvinyl acetate content and sent to the alcoholysis section for alcoholysis. Polyvinyl acetate alcohol solution of polyvinyl acetate and sodium hydroxide methanol solution by polyvinyl acetate: methanol: sodium hydroxide: water ratio of 1: 2: 0.01: 0.002 at the same time by adding high-speed mixer by mixing fully into the belt alcohol And the alcohol solution was carried out at a temperature of 50 ° C. The belt was moved at a speed of 1.1 to 1.2 m / min, and the alcoholysis was terminated in about 4 minutes to obtain a cured polyvinyl alcohol. Crushing, pressing and drying to remove the solvent to obtain finished polyvinyl alcohol. Methyl Acetate Recovery The extruded liquid contains large amounts of methyl acetate and methanol. First, in the azeotropic distillation tower, the azeotrope of methyl acetate and methanol is distilled off, and the bottom of the tower is an aqueous methanol solution. Acetic acid methyl ester and methanol azeotrope into the water extraction separation tower and water mixture, the top of the separation of methyl acetate, the bottom of the methanol solution. The methyl acetate was hydrolyzed by ion exchange resin in a hydrolyzer to obtain a mixture of acetic acid and methanol. The mixture was sent to a distillation column of the hydrolyzate, and methanol and unhydrolyzed methyl acetate were distilled off, and the mixture was transferred to a water extraction column. Hydrolysis distillation tower at the end of dilute acetic acid, sent to dilute acetic acid concentration tower in the dehydration of acetic acid. Azeotropic distillation tower and water extraction separation bottom of the methanol solution obtained in methanol distillation column distillation of methanol can be reused.

    More

    China Polyvinyl Alcohol (PVA) Export Data

    Data referenced from General Administration of Customs,P.R.China

    2018.11-2019.11 China - America  Polyvinyl Alcohol (PVA) Export Data

    From 2018.11 to 2019.11, total export volume of Polyvinyl Alcohol (PVA) from China to America was 2,616,685KG while total export value was $4,976,104. The biggest proportion of exporting volume in the last 12 months was 21.78% in 2019.08.

    2018.11-2019.11 China Polyvinyl Alcohol (PVA) Export Data

    From 2018.11 to 2019.11, total export volume of Polyvinyl Alcohol (PVA) from China was 170,067,311KG while total export value was $298,497,800. The biggest proportion of exporting volume in the last 12 months was 9.75% in 2019.07.

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