Introduction

The  Polyvinyl Alcohol is made from vinyl acetate produced by means of the calcium carbide route, with methanol as its solvent and azo-diisobutyronitrile as the initiator, through polymerization, alcoholysis, disintegration, separation and desiccation. This company has now had two sets of PVA production devices, one produces flocculent PVA of high alkali alcoholysis, the other does flaky PVA of low alkali alcoholysis.The major specifications of Polyvinyl Alcohol (PVA) of our company are the following series of 17-99F(L), 17-99F(H), 17-99 (L), 17-99(H), 18-99(L), 18-99(H), 19-99(L), 22-99(L), 19-88, and the like. Special PVA of different viscosity and alcoholysis can be produced according to the requirements of our customers. Besides, PVA powder with mesh numbers 20-60 can also be provided.The PVA production facilities of our company have been perfecting day by bay with the long-term absorption and technological transformation on the basis of importing the complete set of technology from Kuraray Company of Japan. PVA produced by our company is good in performances and stable in quality. It enjoys a great reputation both at home and abroad.

CharacteristicsPolyvinyl Alcohol is a kind of non-ionic linear high polymer. It is non-toxic, non-smelly, and it looks white or light yellow, in the form of floccules, flakiness and solid powder. Its molecular formula is (C2 H4 O)n, of which "n" refers to the average degree of polymerization and the molecular weight is 44n. The molecular formula of PVA 17-88 is (C2 H4 O)n-(C2 H6O)m, of which "n + m" is the average degree of polymerization and the molecular weight is 44n+86m. The simulating specific gravity of flocculent PVA is (0.21-0.30)g/cm3, while that of flaky PVA is (0.47+-0.06)g/cm3.Polyvinyl Alcohol has fairly good chemical stability, insulativity and film-forming properties. It has typical chemical properties of polyalcohol.It can react with acid, ether and acetyl, and it can be esterified, etherified and actualized. In addition, it has unique characteristics of its own as follows:

Water Solubility:Water solubility of PVA differs a little with different alcoholysises and viscosities. Based on the characteristics of our products, it's suitable to adopt the dissolving procedures as follow:1. Add a moderate amount of clean water into the dissolving kettle on condition of room temperature.2. Add calculated PVA into the dissolving Kettle little by little and fully stir it. The stirring speed should be controlled at about 100 revolutions per minute, and keep it soaked for 30-60 minutes after finishing stirring.3. Heat with steam to a proper temperature step by step, and at the same time, keep stirring till PVA is completely dissolved. Heating can be done directly on an open fire without steam, but the density of the mixed liquor can never be higher the 10%. Remember constant stirring can prevent it from being burnt. The right temperature for PVA of thorough alcoholysis is between 95c and 98c, and no boiling has to be dome. Heating to 60c may do to PVA 17-88.4. Methods to distinguish whether PVA is completely dissolved:a. Base on the operating experiences.b. Put some dissolved PVA liquor in a beaker, and observe it in a bright place, if it's clear and no transparent particles can be seen, then PVA in the kettle is completely dissolved.c. Measure the viscosity. The viscosity of the liquid won't change under the same condition after about 30 minutes.5. It is natural to blister when PVA is being dissolved. Heating and stirring at interval can be done if this phenomenon is serious, or lower down the dissolving temperature and stirring speed of revolutions to a proper degree. (If necessary, a moderate amount of deformers, such as caprylic alcohol and tributylphosphate can be added in.)6. When the dissolution of flaky PVA is coming to the end, flow down from the kettle is to be employed, and the valve at the bottom must be opened and part of the bottoms have to be let out (This part can be put into the kettle again for dissolution). So that the valve at the bottom is unblocked.

Quality standard (Q/OWAL001-2006:

 LOW ALKALI PVA

Storage stability of PVA liquor:No chemical change will take place for keeping PVA liquor long. On condition of room temperature, its viscosity will be rising with time passing by. The liquor will turn into gel at low temperature, and it can change back into liquor again when it is heated and stirred. If it is laid up long, antirust agent, anticorrosion agent, anti-gel agent and viscosity stabilizer, etc. Can be added in. But attention must be paid to the influence on the quality and characteristics of the products concerned due to the application of additives.

Caking property:PVA liquor has very strong caking power with hydrophilic cellulose; its viscosity rises with the increase of its alcoholysis and polymerization degree.Chemical property of its interface:PVA possesses surface activity that can reduce the surface tension of water.

Solvent resistance:PVA is soluble in polar liquor with hydroxyl group, but it's easy to change into gel. Generally, it's neither soluble in non-polar organic liquor nor in inorganic acid. Water is its best solvent.

Heat stability:PVA owns good heat stability. No change will take place below 140c.

Packing

flccument pva:12.5kg/bag  flake pva:20kg/bag  powder:25kg/bag

Transportation and storage:Transportation: Means of conveyance must be clean and equipped with weather-cloths so as to keep PVA off moisture, rains and sunlight. Careful handles with the packages save them from being scratched and broken.

Storage: PVA must be laid in a dry and well-ventilated place, keep it away from insulation, moisture, central heating or other heaters. 

Poly vinyl alcohol CAS: 9002-89-5