PVA MANUFACTURER---LIWEI CHEMICAL CO. LTD

The Synthesis Steps and Inspection Method of Vinyl Acetate

Synthesis Steps:
Equipped with thermometers, reflux condenser, drip the four funnels and Stirrers included Polyvinyl Alcohol and distilled water in the flask, heat up to 80 ℃, starting stirring until completely dissolved, the temperature to 65 ℃. Join mixing emulsifying agent (non-ionic emulsifier OP-10 and anions 1/2 alkyl benzene sulfonic acid sodium salt mixture). Initiator of one-second and one-third monomers, reaction 2 h at this temperature, add remaining initiator, began dropping the remaining two-thirds monomer Vinyl Acetate Monomers and modification of modifiers 1 and modifier 2. Control of acceleration drops, continuing reaction 3 h, add appropriate amount of plasticizer (dibutyl phthalate), continue to stir reaction 20min, over reaction. Synthesis of Vinyl Acetate in the presence of acetic acid polymer degree of polymerization by 250~600, polymerization is complete, resin of residual traces in the catalyst (usually a peroxide), monomers and (or) dispose of vacuum drying, steam stripping, cleaning or treatment method to remove.
Inspection Method:
1. Determination of film time. A certain amount of Polyvinyl Acetate emulsion on glass, evenly layer, natural after drying film to record accurately the film time, 3 sets of parallel test each sample, and its average, the film formation time measured shall be final.
2. Determination of resistance to water. Polyvinyl Acetate emulsion coating on the glass, film at room temperature, the two-thirds part of the glass plate is immersed in water, recording the film completely fall off the time, characterized by shedding its water resistance, longer water resistant as possible. Mine climate is relatively large, so ask for better water resistance.
3. Determination of viscosity. Wuzhi viscometer used viscosity of Polyvinyl Acetate emulsion, test temperature is 30 degrees Celsius. In order to facilitate spraying in coal mine construction, we should control the viscosity is not too big, and viscosity is too little adhesion bonding of coal and reduce, to control the viscosity is comparatively moderate.