Academic name: Polyvinyl Alcohol
English name: Polyvinyl alcohol
English abbreviation: PVA
Polyvinyl alcohol (PVA) is a white, stable, and non-toxic water-soluble polymer made by polymerization and alcoholysis of vinyl acetate, in the form of powder, flake, or flocculent solids.
Polyvinyl alcohol contains many alcohol groups, has polarity, and can form hydrogen bonds with water, making it soluble in polar water; It is also soluble in hot hydroxyl containing solvents such as glycerol and phenol, but not in general organic solvents such as methanol, benzene, acetone, gasoline, etc.
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Physical and chemical properties
1、 Physical properties
A. Solubility: Polyvinyl alcohol powder can dissolve in water. Polyvinyl alcohol Resin (PVA) with an alcoholysis degree less than 95% can be dissolved in room temperature water, while polyvinyl alcohol resin (PVA) with an alcoholysis degree greater than 99.5% can only be dissolved in hot water above 95 ℃.
B. Thermal stability: Polyvinyl alcohol will soften when heated, and there is no significant change below 40 ℃. Glass transition temperature: 75-85 ℃, and gradually discolor and embrittle when heated above 100 ℃. Above 160 ℃, prolonged heating will gradually stain, dehydrate and etherify, and lose solubility; At temperatures above 220 ℃, decomposition occurs, generating water, Acetic Acid, acetaldehyde, and butyraldehyde; Polymers containing conjugated double bonds at temperatures exceeding 250 ℃.
C. Chemical resistance: PVA is almost unaffected by weak acids, bases, or organic solvents, and has high oil resistance.
D. Storage stability: PVA is a low viscosity polymer, and its aqueous solution is very stable at room temperature. The aqueous solution will not deteriorate during storage.
E. Film forming property: Due to the high adhesion between PVA molecules, PVA is easy to form a film, resulting in a colorless and transparent film with good mechanical strength, a smooth surface without sticking, and good solubility. The molecular membrane has good light transmittance, high moisture permeability, no charge, no dust absorption, and good printability.
2、 Chemical properties
PVA can be regarded as a linear polymer with secondary hydroxyl groups. The hydroxyl group in the molecule has high activity and can carry out typical chemical reactions of low alcohols, such as esterification, etherification, acetalization, etc. It can also react with many inorganic compound or organic compounds.
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Packaging, transportation, and storage:
Product appearance: white flocculent, flaky, or powdery solid. This product is a non hazardous material, non explosive, non oxidizing, non corrosive, non radioactive, and non toxic and harmful.
1. Packaging
12.5 kg, 20 kg, 25 kg plastic woven bags or paper bags, packaged in 750kg to 1000kg plastic woven ton bags.
2. Transportation
Use clean transportation tools to prevent moisture, rain, and sun damage. Handle with care during handling to prevent scratching or breaking the packaging.
3. Storage
In a dry and well ventilated room with a room temperature of 5-30 ℃. Please do not approach heat sources, strictly prevent dampness, and avoid direct sunlight. It is strictly prohibited to store together with volatile chemicals to prevent adsorption and deterioration.
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Product Application
Polyvinyl alcohol resin (PVA) aqueous solution has excellent film-forming and emulsifying properties. It can be used as a protective colloid for polymer emulsification and suspension polymerization reactions.
Polyvinyl alcohol can be used in fields such as textile pulp, Vinyl fiber, paper coating agents, building materials, adhesives, PVA films, PVB raw materials, food and medicine, etc. PVA can also be used as soil improver, polymer suspension agent and emulsifier, quenching agent, etc. In addition, with the continuous development and improvement of PVA performance, its use is still expanding.
Various models and uses of polyvinyl alcohol (PVA)
1. Vinylon raw materials:
Polyvinyl alcohol is dissolved, spun, and then subjected to acetalization treatment to produce vinylon fibers. It can be blended with cotton, wool, viscose fibers, etc. to produce vinylon textiles, which are widely used in clothing, tarpaulins, cord cords, fish net ropes, etc. Generally, it is better to choose PVA17-99 with an average polymerization degree of 1750 ± 50 as the spinning material
2. Warp Size:
a. A size mainly composed of polyvinyl alcohol has good adhesion to cotton, linen, polyester, and vinylon viscose fibers. After film formation, it is smooth and smooth, sturdy and wear-resistant, promoting the suitability of warp yarns and reducing friction and bending during the weaving process. Intense movements such as stretching cause warp breakage, reducing the breakage rate of the fabric machine. And the woven fabric has a crisp feel. Smooth and delicate, the fabric surface is not rough.
b. Polyvinyl alcohol is a water-soluble polymer compound that is convenient for sizing, sizing, and desizing. Generally, it is better to choose polyvinyl alcohol (such as PVA15-99, 16-99, 17-99) with a lower average degree of polymerization as the slurry.
3. Adhesive:
a. The aqueous solution of polyvinyl alcohol has strong adhesion to materials containing cellulose (such as paper, cloth, wood, etc.), and has the advantages of safety and non-toxicity. It can be used for laminating cardboard, bonding corrugated cardboard, and office adhesive. Kraft paper bags used for packaging heavy items such as cement, fertilizers, grains, etc. also use PVA as the adhesive.
b. Urea formaldehyde resin and phenolic resin modified with polyvinyl alcohol can be used as adhesives for laminates and artificial boards.
c. Polyvinyl alcohol aqueous solution (by adding appropriate fillers and additives) is also widely used to prepare adhesives for printing, binding, paper tubes, cardboard boxes, and other paper connections.
d. Under the catalysis of ACID, polyvinyl alcohol can condense with formaldehyde, butyraldehyde, glyoxal, or other aldehydes to produce polyvinyl alcohol acetals (such as PVAF, PVB) with stronger water resistance, adhesion, and mechanical strength, which are widely used in construction, coatings, adhesives, safety glass interlayers, and other fields. As the degree of polymerization of PVA increases, the viscosity of acetals increases.
e. Polyvinyl alcohol is an excellent protective colloid and dispersant for homopolymerization of vinyl acetate or copolymerization with other monomers to produce lotion (white glue), which is crucial in the production of white glue. Generally, the viscosity of the produced lotion increases as the polymerization degree of polyvinyl alcohol increases. Partial alcoholysis polyvinyl alcohol (17-88) is used in combination with complete alcoholysis polyvinyl alcohol (such as 17-99, 19-99, etc.). The use of partial alcoholysis polyvinyl alcohol can increase the stability of lotion, and the use of complete alcoholysis polyvinyl alcohol can increase the water resistance of lotion.
4. Paper processing:
a. Polyvinyl alcohol can be used as a surface sizing agent for paper in the papermaking industry, with good film-forming properties and high film strength. It can improve the printing adaptability, smoothness, friction resistance, folding resistance, oil resistance, and chemical resistance of paper. Choosing PVA with an average polymerization degree of 1750 ± 50 as the surface sizing agent for paper is good.
b. Pigment processing agent: It can improve the whiteness and glossiness of coated paper, provide good printing gloss, bright color, and improve paper quality. It is better to choose polyvinyl alcohol with a higher average degree of polymerization.
c. As an internal sizing agent for paper: When making paper, powdered polyvinyl alcohol is added to the pulp to beat and make paper, resulting in high strength paper. It is better to choose polyvinyl alcohol with a higher average degree of polymerization.
5. The polyvinyl alcohol film made from this product has good transparency, high tensile and crack resistance, good moisture permeability and gas barrier, oil resistance, organic drug resistance, and no static electricity, making it suitable for packaging textiles.
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product price
The price of polyvinyl alcohol for different purposes varies greatly. The general market price is 10-50 yuan/kg, and the average price is 30.5 yuan/kg.
