The Synthesis Steps and Inspection Method of Vinyl Acetate
ANHUI LIWEI CHEMICAL CO.,LIMITED
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.