Polyvinyl Alcohol (PVA) is the only currently found it is soluble in water and non-toxic polymer, also known as PVA, Poval. It is a high molecular compound developed in recent thirty years, due to declining continuously improve the synthetic technology and price, its use more widely, the development speed is very quick. Whose properties are between rubber and plastic, according to use can be divided into fiber and non fiber two uses. Polyvinyl Alcohol is a kind of colorless plastic, made of polyethylene ester (usually polyvinyl acetate) by acid or alkali hydrolysis. Fully hydrolyzed Polyvinyl Alcohol, still contains about 5% residual vinyl. The physical properties, water resistance of Polyvinyl Alcohol and toughening agent and the degree of hydrolysis of mixed etc, and in the final products in the proportion of acetic acid radical and hydroxyl. Polyvinyl Alcohol in organic solvents and gases are impermeable, nor with the mixture. Besides the polyhydric alcohol, ammonia alcohol, to the mix solvent and water resistance of the majority can. Fully hydrolyzed Polyvinyl Alcohol soluble in hot water. The lower the degree of hydrolysis, resistance to water more, adding various additives can increase its water resistance. The viscosity of polymer can be controlled by adjusting the initial viscosity of the polyethylene acetate.
The series of products of polyvinyl alcohol resin can be dissolved in hot water below 95 ℃, but because of the degree of polymerization, alcoholysis degree of alcoholysis of different, different ways have some difference in the dissolution time, temperature, and therefore the use of different brands of polyvinyl alcohol resins, dissolution method and time to explore. When dissolved, can stir the escape fully swelling, dispersing and volatile materials the product slowly added about 20 ℃ in cold water (do not over 40 ℃ water by adding the product directly to dissolve, to avoid a bag shape and skin soluble endogenous phenomenon), and then heated to 95 ℃ accelerated dissolution, and holding for 2 to 2.5 hours, until the solution is no longer contain tiny particles, then through 28 mesh stainless steel filter impurities, to spare.
The stirring speed of 70 to 100 rpm, the temperature, the jacket, water bath, indirect heating, can also be by steam direct heating; however, do not use direct fire heating, in order to avoid local overheating and decomposition, if there is no mixer, steam for tangential blowing, dissolved.
The concentration of aqueous solution of polyvinyl alcohol resin series products in general 12 ~ 14%; degree of alcoholysis of polyvinyl alcohol resin product water solution concentration is generally available in about 20%.
Test the product is completely dissolved: take a small amount of solution, adding 1 to 2 drops of iodine solution, if appear blue granular transparent body, that has not been completely dissolved, such as color can be diffused, that have been completely dissolved.
The series of products of polyvinyl alcohol resin can be dissolved in hot water below 95 ℃, but because of the degree of polymerization, alcoholysis degree of alcoholysis of different, different ways have some difference in the dissolution time, temperature, and therefore the use of different brands of polyvinyl alcohol resins, dissolution method and time to explore. When dissolved, can stir the escape fully swelling, dispersing and volatile materials the product slowly added about 20 ℃ in cold water (do not over 40 ℃ water by adding the product directly to dissolve, to avoid a bag shape and skin soluble endogenous phenomenon), and then heated to 95 ℃ accelerated dissolution, and holding for 2 to 2.5 hours, until the solution is no longer contain tiny particles, then through 28 mesh stainless steel filter impurities, to spare.
The stirring speed of 70 to 100 rpm, the temperature, the jacket, water bath, indirect heating, can also be by steam direct heating; however, do not use direct fire heating, in order to avoid local overheating and decomposition, if there is no mixer, steam for tangential blowing, dissolved.
The concentration of aqueous solution of polyvinyl alcohol resin series products in general 12 ~ 14%; degree of alcoholysis of polyvinyl alcohol resin product water solution concentration is generally available in about 20%.
Test the product is completely dissolved: take a small amount of solution, adding 1 to 2 drops of iodine solution, if appear blue granular transparent body, that has not been completely dissolved, such as color can be diffused, that have been completely dissolved.