What is polyvinyl alcohol
Polyvinyl alcohol is an organic compound, the chemical formula is [C2H4O]n, the appearance is white flake, flocculent or powdered solid, odorless. Soluble in water (above 95℃), slightly soluble in dimethyl sulfoxide, insoluble in gasoline, kerosene, vegetable oil, benzene, toluene, dichloroethane, carbon tetrachloride, acetone, ethyl acetate, methanol, ethylene glycol, etc.
Function and use of polyvinyl alcohol
Polyvinyl alcohol is an important chemical raw material used in the manufacture of polyvinyl acetals, gasoline-resistant pipes and vinylans, fabric treatment agents, emulsifiers, paper coatings, adhesives, glues, etc.
1, Vinylon raw materials
Vinylon fiber can be produced by polyvinyl alcohol after dissolution, spinning, and then by acetal treatment, which can be blended with cotton, wool, viscose fiber to make vinylon textile, widely used in clothing, cloth, cord, fish net rope.
2. Warp sizing
A. PVA based slurry has good adhesion to cotton, hemp, polyester and vinylon viscosa fibers, smooth and smooth after film formation, both strong and wear-resistant, promote the suitability of warp yarn and reduce warp friction and bending in the weaving process. Tensile and other intense movement causes warp breakage and reduces the breakage rate of cloth machine. And the fabric feels crisp. Smooth and delicate, cloth surface is not rough.
b, polyvinyl alcohol is water-soluble polymer compounds, mixing, sizing, desizing are very convenient.
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 cardboard lamination, bonding of corrugated cardboard and office glue. Kraft paper bags used for packing heavy objects such as cement, fertilizer, grain, etc., also use PVA as an adhesive.
b, polyurea resin and phenolic resin modified by polyvinyl alcohol can be used as adhesives for laminates and wood-based panels.
c, polyvinyl alcohol aqueous solution (by adding appropriate fillers, additives) is also widely used in the preparation of printing and binding, paper tubes, cartons and other paper products required for the connection of adhesives.
d, under the catalysis of acid, polyvinyl alcohol condensates with formaldehyde, butyraldehyde, glyoxal or other aldehydes to generate polyvinyl acetals with stronger water resistance, adhesive force and mechanical strength (such as PVAF, PVB), which are widely used in building construction, coatings, adhesives, safety glass interlayers and other fields.
e, polyvinyl alcohol is an excellent protective colloid and dispersant for the production of emulsion (white glue) by homopolymerization of vinyl acetate or copolymerization with other monomers, which is crucial in the production of white glue.
4, paper processing
A. Polyvinyl alcohol can be used as a paper surface sizing agent in the paper industry. It has the characteristics of good film formation and high film strength, which can improve the printing adaptability, smoothness, friction resistance, folding resistance, oil resistance and chemical resistance of paper.
b, pigment processing agent: can improve the whiteness and gloss of coated paper, printing luster is good, bright color, improve paper.
c, internal sizing agent for paper: When making paper, add powdered polyvinyl alcohol and pulp together to beat and make paper, so that the paper obtained has high strength.
5, polyvinyl alcohol film
The film made of this product has good transparency, high tensile and cracking strength, good moisture permeability, good gas insulation, oil resistance, organic drug resistance, no static electricity, so it is suitable for the packaging of textiles. In addition, it can be combined with polyethylene and polypropylene for instrument packaging. A small amount is used for optics and other aspects.
Is PVA resin toxic
Pharmaceutical grade polyvinyl alcohol, different from chemical grade polyvinyl alcohol, it is a very safe polymer organic matter, non-toxic to the human body, no side effects, with good biocompatibility, especially in the medical treatment such as its water-based gel in ophthalmology, wound dressing and artificial joint has been widely used, while in the polyvinyl alcohol film in medicinal film, artificial kidney membrane and other aspects are also used.
Its safety can be seen in products used for wound skin repair, and eye drops. Some of these models are also commonly used in facial masks, cleansers, toners and lotions in cosmetics, and are a common safety film forming agent.