Polyvinyl Alcohol (PVA) is one of the few artificially synthesized high molecular weight polymers with water solubility. Its chemical formula is (C2H4O) n, where n represents the degree of polymerization. The grades of polyvinyl alcohol are usually composed of polymerization degree and alcoholysis degree. In 1788, "17" represents a degree of polymerization of approximately 1700, and "88" represents an alcoholysis degree of 88%. Its main performance indicators include polymerization degree, alcoholysis degree, and other special performance indicators. At present, Japanese companies can synthesize products of over 200 grades, while domestic companies can also achieve over 100 grades through continuous research and development. Due to the properties and price of PVA itself, its applications are constantly expanding.
1、 The relationship between the structure and properties of PVA: PVA contains a large number of hydroxyl groups (- OH), which endow it with good water solubility and viscosity; It also contains vinyl groups (- CH2-CH -) in its structure, providing certain strength and toughness; PVA may also contain a small amount of vinyl acetate units, which can affect its solubility and thermal stability. Due to the presence of a large number of hydroxyl groups in its molecular structure, PVA also has good water solubility and hydrophilicity, which change with the degree of polymerization and alcoholysis. In addition, PVA also has certain thermal stability, chemical stability, mechanical properties, optical properties, moisture absorption, and biocompatibility.
2、 The main production process of PVA is: polyvinyl acetate is polymerized in solution to produce polyvinyl acetate, which is then subjected to alcoholysis reaction to produce polyvinyl alcohol.
3、 PVA has excellent properties and a wide range of applications. Initially used as a raw material for vinylon fibers, it gradually gained widespread development and application in non fiber fields, greatly expanding the application areas and development prospects of PVA. PVA has many excellent properties such as water solubility, fiber forming ability, adhesion, film-forming ability, emulsion stability, dispersion stability, oil resistance,
ACID and alkali resistance, chemical reactivity, biodegradability, etc. Through modification, it can also obtain melt (or thermoplastic) processing performance and many special and specialized properties. PVA is widely used in industries such as textile, papermaking, construction, chemical, printing, packaging, medicine, daily chemical, agriculture, ceramics, steel, electronics, electrolysis, electroplating, etc. With the continuous development of product technology, its application fields are still further expanding.
4、 Examples of specific uses of PVA
（1） Raw materials for vinylon. Due to its high strength, low elasticity, large modulus, good acid and alkali resistance, and weather resistance required for industrial fibers, as well as excellent adhesion with rubber, vinylon occupies a special position in the field of industrial applications.
（2） Warp yarn slurry. PVA has excellent sizing properties and can be used for sizing hydrophobic synthetic fibers and their blended yarns, achieving satisfactory results. The polyvinyl alcohol of the 088 series has excellent water solubility and is easily desizing. For example, it is recommended to use 088-20 for wool yarn, linen yarn, wool, and synthetic silk. Silk, nylon, and polyester all have corresponding grades, so they will not be listed one by one.
（3） Paper processing. Water soluble PVA is mainly used as a surface sizing agent, pigment binder, and pulping machine additive in the paper industry. 100-27 can be used as an adhesive for ordinary paper processing. Copperplate paper base, photo paper base, fire-resistant paper, security paper, release paper, thermal recording paper, inkjet recording paper require corresponding grades of products, so they will not be listed one by one.
（4） Adhesive. Such as kraft paper bags, corrugated paper bags, office adhesives, etc.
（5） Paint. Polyvinyl alcohol can condense with formaldehyde to form polyvinyl formal, which is used for interior and exterior wall coatings of buildings.
（6） Thin film. Due to its excellent barrier properties, PVA can be processed into oxygen barrier films through special techniques. When combined with PE and adhesives, it can be used to create multi-layer barrier films that can be used as food barrier materials. Such as ham sausage packaging, Soy egg packaging, beef packaging. Its price is nearly half cheaper than ethylene vinyl alcohol (EVOH), making it a promising packaging material. Due to its water solubility, PVA can also be made into "Bi Li Zhu" and placed in a washing machine for washing.
（7） Polyvinyl butyral (PVB).
（8） Suspension dispersant PVA is often used as a dispersion stabilizer in suspension polymerization of vinyl chloride monomer (VCM), with excellent gel retention and surface activity properties. According to the degree of polymerization and alcoholysis of PVA, selecting appropriate specifications of PVA can greatly optimize the properties of
PVC Resin. The properties of PVA greatly affect the characteristics of PVC powder.
（9） PVA sponge, after adding foaming agent and moderate formaldehyde reduction, can be made into PVA sponge with special properties. It can be used to make filter materials, makeup powder puffs, household wiping tools (such as brooms and mops), industrial rollers, etc. It has the advantages of solvent resistance, good elasticity and softness after absorbing water, and good touch to the skin.
（10） Other applications
Cosmetics: PVA has emulsifying property, adhesive property, film-forming property and proper viscosity, and is suitable for use as the emulsifier of oil lotion, as well as the main ingredient of skin care cream, facial
Mask, etc.
Pharmaceutical: PVA can be used as a granulation agent for pharmaceuticals, pesticides, bandage adhesives, as well as a thickening agent for well-known eye drops, medical hot compress materials, etc.
Agriculture and forestry: PVA can be used as a soil amendment and plant seed fixative. It can effectively prevent soil compaction and acid erosion, promote plant growth, prevent soil erosion, and stabilize soil.
Raw materials for various derivative products: PVA can be used to produce formaldehyde resins and other aldehyde resins, as well as photosensitive resins such as vinyl cinnamate graft polymerization.
PVA can also be used as PVA rubber, photosensitive material, high-frequency quenching agent, cathode ray tube, optical polishing agent, moisture-proof agent, etc.
