DE3005889C2 - - Google Patents

Description

You can polymerize ethylenically unsaturated monomers by making the monomer or monomers in Presence of one or more emulsifiers emulsified in water and then with the help of radical-forming catalysts polymerized. Generally these are catalysts water soluble. Peroxides or so-called redox are common catalysts.

DE-OS 28 41 033 discloses polymer dispersions to produce from emulsions. However, additional emulsifiers are required or other auxiliaries used in this process will.

The invention is based on the knowledge that azo groups containing polymers (prepolymers containing azo groups) of Formula I.

in the

P₁einen polymer block, which was formed from acrylamide, N.Vinylpyrrolidon, acrylic acid, methacrylic acid, esters of acrylic and methacrylic acid, vinyl ester, styrene or styrene derivative, pure aliphatic, cycloaliphatic or aromatic radical with up to 35 carbon atoms, optionally oxygen as a hetero atom contains or is a polyether, n is a number from 1 to 10⁴, m is a number from 1 to 100

mean,
can perform both the function of the emulsifier and the catalyst in an emulsion polymerization of ethylenically unsaturated monomers. The polymers containing azo groups are thereby decomposed.

Monomers M₁, which are used to form P₁, are acrylamide, N-vinylpyrrolidone, Acrylic acid, methacrylic acid, esters of acrylic and methacrylic acid, Vinyl ester, styrene and styrene derivative.

The prepolymers I containing azo groups are prepared by a polyazo initiator of formula II

in the

R has the meaning given above, n is a number from 1 to 10⁴

mean,
is partially decomposed in the presence of ethylenically unsaturated monomers. 5 to 90%, preferably 30-70%, of the azo groups are decomposed. The decay of the azo groups is controlled by the choice of temperature and time. The time is varied between 10 seconds and 8 days, preferably 1 minute and 3 days, and the temperature between 30 and 110 ° C, preferably 40 and 80 ° C.

The polyazo initiators II can by reacting azo bisisobutyronitrile can be prepared with diols. The  Diols have the formula III

HO-R-OH (III)

wherein

R has the meaning given above.

Suitable diols are in particular:
1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, di-, tri-, tetraethylene glycol, polyethylene glycol with average molecular weights from 200 to 2000 and polytetrahydrofurans with average molecular weights from 200 to 2000.

Process for the emulsion polymerization of ethylenically unsaturated Monomers on radical forming catalysts and in Presence of emulsifiers, which is characterized in that as monomers to be polymerized, vinyl acetate, acrylonitrile, Styrene, methyl methacrylate, ethyl acrylate, acrylamide, N-vinyl pyrrolidone or butadiene, as a catalyst and emulsifier 0.1 to 50 parts by weight per 100 parts by weight of monomer Polymers of the formula I.

in which

n is a number from 1 to 104, m is a number from 1 to 100, purely aliphatic, cycloaliphatic or aromatic radical having up to 36 carbon atoms, which optionally contains oxygen as a hetero atom or is a polyether, and P 1 is a polymer block which is composed of acrylamide, N - Vinylpyrrolidone, acrylic acid, methacrylic acid, esters of acrylic and methacrylic acid, vinyl esters, styrene or styrene derivative was formed,

mean,
used.

Homopolymers or copolymers of several can be used Monomer can be produced.

In emulsion polymerizations, ionic ones are usually used Surfactants used. Stabilizing the emulsified Particles are created by the accumulation of charge the surface of these particles. With the described here Processes are polymer blocks P₁ of prepolymer I  enriched on the surface of the emulsified particles. The emulsified particles are stabilized by Solvation of the polymer blocks P₁ by the surrounding Solvent. Therefore, according to the one described here Process emulsions both in water and in organic solvents. The prepolymer I must be chosen so that P₁ in the emulsifying liquid is soluble. For emulsions polymerization in water is P₁ for example polyacrylic amide, in alcohols P₁ is, for example, poly-N-vinyl pyrrolidone, in petroleum ether (hydrocarbons) is P₁ for example poly-i-octyl methacrylate.

To carry out emulsion polymerization in water you can a polymer containing azo groups Formula I with P₁ = polyacrylamide in water to a 0.1 dissolve up to 20% solution. Emulsified in this solution then the monomer or monomers in such an amount, that the emulsion contains 5 to 50 wt .-% monomer. The Polymerization is started by heating the polymerization batch. The duration and temperature of the polymerization are chosen so that they have at least one half-life correspond to the initiator decay.  

• Preparation of the azo group-containing polymers of the formula II
  • 1. Initiator / monomer ratio 1: 6
  • The reaction apparatus, consisting of 500 ml three-half-flask with Teflon paddle stirrer, internal thermometer, reflux condenser with bubble counter and nitrogen inlet, was flushed with nitrogen at 78 ° C. for 1 hour before the start of the reaction. A solution of 5 g of polyinitiator in 90 ml of t-butanol was then added in a nitrogen countercurrent. A solution of 30 g of acrylamide in 250 ml of t-butanol was pumped in over the course of an hour using a piston pump. The reaction temperature was kept at 78 ° C. for a further 15 minutes, then the reaction was stopped by cooling with ice, the polymer which had precipitated during the reaction was filtered off with suction and dried at room temperature in an oil pump vacuum. The stirring speed was 600 rpm; the 75 minute reaction time corresponds to 37% initiator decay. Viscometric molecular weight determination gave values between 60,000 and 70,000 g / mol for different batches.
  • 2. Initiator / monomer ratio 1:50
  • Reaction apparatus, time and temperature as described above, initiator and monomer solution in t-butanol were filled into the apparatus right at the start of the reaction. The solution was 10% acrylamide. The average molecular weights of various batches determined by viscometry were approximately 180,000 g / mol.

Claims (3)

1. Process for the emulsion polymerization of ethylenically unsaturated monomers on radical-forming catalysts and in the presence of emulsifiers, characterized in that vinyl acetate, acrylonitrile, styrene, methyl methacrylate, ethyl acrylate, acrylamide, N-vinylpyrrolidone or butadiene, as catalyst and emulsifier, as the monomers to be polymerized , 1 to 50 parts by weight per 100 parts by weight of monomer of a polymer of the formula I. in which n is a number from 1 to 104, m is a number from 1 to 100, purely aliphatic, cycloaliphatic or aromatic radical having up to 36 carbon atoms, which optionally contains oxygen as a hetero atom or is a polyether, and P 1 is a polymer block which is composed of acrylamide, N-vinylpyrrolidone, acrylic acid, methacrylic acid, esters of acrylic and methacrylic acid, vinyl ester, styrene or styrene derivative were formed,
used. 2. The method according to claim 1, characterized in that that P₁ is a polymer block made of polyacrylamide, Polyacrylic acid, polymethacrylic acid or Is polyvinyl pyrrolidone, and that the polymerization is carried out in water.   3. The method according to claim 1, characterized in that in organic solvents is polymerized and P₁ from a polymer block exists in the solvent used is soluble.