PVA resin is a kind of heavy polymer. It is white or light yellow floc, Granular or powdery in appearance. Its molecular formula is [CH₂CHOH]n，and the molecular formula for some of the PVA is-[CH₂CHOH]n-CH₂CHOOCCH₃]m-. PVA is non-toxic, insipid and harmless. PVA is water-soluble and the solvent provide good viscosity and film building. It can withstand oils, lubricants, hydrocarbons and most other organic solvents. PVA has better chemical stability and insulatibility, and provide ease in firm building; It possess the typical chemical properties of polyols and can carry out process of esterification, etherealization, aceatalization etc.

In textile industry, PVOH is mainly used as a warp dressing agent, textile finishing agent and the raw material of vinylon; in construction and upholstery industry 107 glue, it's used as an additive of cement and mortar, inner and outer wall paints, and moulding board binder; and in chemical industry, it's used as a polymer emulsifying agent, dispersing agent and used to produce PVOH formal, PVOH acetal and PVOH butyral. It's used as an adhesive in lumbering and paper-making industries, used as a soil improving agent, pesticide reinforcing agent and PVOH thin film in agriculture, and used as a well-fixing agent in petroleum exploitation. It can also be used into cosmetic, medicine, printing, ceramics, steel-making, electronics and plating.

a. A dissolving kettle with blender should be used, and the dissolving kettle shall be made of materials more resistant to be rusted or corroded, such as stainless steel, ceramics or iron with synthetic resin lining, that could prevent PVA solution from contamination.

b. The speed of the blender shall be approximately 70-100rpm.When the speed is too low, deposit will be probably formed; when the speed is too high, air will be sucked in, resulting in bubbles.

c. Heat should be supplied directly from the air steamer. The dissolving time can be greatly shortened if there is additional jacket steam heating unit. Direct fire heating shall not be adopted, because the bottom of the container might be charred if the solution is not fully blended.

PVA product's dissolvent ability is determined by the degree of alcoholysis and polymerization. When polymerization increased, the ability to dissolve will reduced. Likewise, when the degree of alcoholysis decreased, the dissolvent temperature will reduced and water solubility will increase. Fully alcoholysed PVA products are more sensitive to temperatures changes. Such products cannot dissolve or experience partial swell in properties when temperature falls below required degree. Blending will be difficult and foam created should the temperature exceed the required degree for partial alcoholysis products. Temperature must be controlled at acceptable range for ease of dissolving.

a. Measure the required amount of water at room temperature, and add it into the kettle.

b. Slowly pour in the measured PVA in to the kettle while the blender is working. The PVA shall be pour in slowly, because the partially alcoholysed PVA would agglomerated easily, Do not pour in the whole pack of PVA at one time.  

c. Fully blend to disperse the inflated PVA (about 10-20min) and gradually raise the temperature by 2°C every minute. If the temperature rises too quickly, the solution will produce foam and overflow.

d. Gradually raise the temperature of the completely alcohoylsed PVA up to 98°C, and continue to blend it for 1hour under the constant warmth temperature, till fully dissolved. For the partially alcoholysed PVA, gradually raise the temperature up to 80°C and continue to blend it for about 1 hour under the constant warmth temperature till fully dissolved. Filter and keep it aside for use.

a. Do not add PVA directly into hot water to dissolve as there will be agglomeration

b. Do not use naked flame directly for heating

c. Blending is necessary throughout the whole process.

d. Some foam will be created during the dissolving process when the solution is highly concentrated and  blending speed is fast. To prevent foaming, some de-foaming agent such as 0.01-0.05% of octanol or tributyl phosophate (for PVA), or 0.2-0.5% of organic silica latex (PVA), maybe be added before dissolving process.

? Storage of Solution

Corrode Prevention: As compared with other macromolecular solutions, PVA solution could be stored easier as it does not turned moldy or experienced changes in properties. However, appropriate amount of antiseptic agent   such as 0.01-0.05% (for PVA) formaldehyde or salicylic acid shall be added for long term storage.

Rust Prevention: Stainless or plastic containers are recommended for storage. When iron containers are used, a little amount of weak base shall be added; when copper containers are used 0.02-0.05% (for PVA) sodium nitrite shall be added.

Packing: products in granulose form shall be packed with knit bags made of polypropylene and colorless medium density polythene film, with net weight of 12.5kg.

Products in granular or powdery form shall be packed with knit bags made of polypropylene and colorless medium density polythene film with net weight of 20.0kg or 25.0kg.

Storage: it shall be stored indoor in a well ventilated and dry room, Prevent exposure to dampness, sunlight and rain.

Transportation: during transportation, the products shall be moved gently to prevent damaging the packing bags. Avoid direct contact with Naked flame, when fire happens, any fire fighting equipment may be use to extinguish the fire.