Preparation of methyl methacrylate polymer powders for use in plastisols
AssigneeE. I. Du Pont de Nemours and Company
InventorBoynton Graham
Life of this patent
Estimating the term…
Abstract
Methyl methacrylate polymer powders especially suitable for making plastisols and organosols are prepared by an improved process comprising stepwise emulsion polymerization in aqueous media in the absence of emulsifiers and surfactants and in such manner that at least most of the monomer added at each step is consumed before the addition of the succeeding portion, followed by isolation of the polymer powder by evaporation of the latex at a temperature that is at least 30.degree. C., preferably 40.degree.-50.degree. C., below the glass transition temperature of the polymer.
Claims17
In an emulsion polymerization process for the preparation of methyl methacrylate polymers and copolymers containing at least 60% by weight of methyl methacrylate units, which comprises (a) adding stepwise in two or more steps with vigorous mixing in water at least one monomer which is methyl methacrylate, together with a polymerization initiator and chain transfer agent whereby at least most of the monomer added in any given step is consumed before the addition of the next succeeding portion, and (b) isolating the resulting polymer;
- the improvement which comprises the stepwise addition in step (a) occurring in the absence of any emulsifier and surfactant, and the isolation step (b) occurring at a temperature that is at least 30.degree. C. below the glass transition temperature of the polymer product.
A process for the preparation of plastisols and organosols which comprises
- (1) preparing methyl methacrylate polymers and copolymers containing at least 60% by weight of methyl methacrylate units by an emulsion polymerization process which comprises
- (a) adding stepwise in two or more steps with vigorous mixing in water, in the absence of any emulsifier and surfactant, at least one monomer which is methyl methacrylate, together with a polymerization initiator and chain transfer agent whereby at least most of the monomer added in any given step is consumed before the addition of the next succeeding portion, and
- (b) isolating the resulting polymer at a temperature that is at least 30.degree. C. below the glass transition temperature of the polymer product;
- and
- (2) dispersing the isolated methyl methacrylate polymers and copolymers in a surfactant-free medium that comprises a compatible liquid plasticizer that is nonvolatile at room temperature and is not a monomer of any of the polymeric components.
A process for the preparation of photosensitive plastisols and organosols which comprises
- (1) preparing methyl methacrylate polymers and copolymers containing at least 60% by weight of methyl methacrylate units by an emulsion polymerization process which comprises
- (a) adding stepwise in two or more steps with vigorous mixing in water, in the absence of any emulsifier and surfactant, at least one monomer which is methyl methacrylate, together with a polymerization initiator and chain transfer agent whereby at least most of the monomer added in any given step is consumed before the addition of the next succeeding portion, and
- (b) isolating the resulting polymer at a temperature that is at least 30.degree. C. below the glass transition temperature of the polymer product;
- and
- (2) dispersing said isolated polymers and copolymers in a surfactant-free medium that comprises a compatible liquid plasticizer that is nonvolatile at room temperature and is not a monomer of any of the polymeric components, a photopolymerizable ethylenically unsaturated monomeric compound, and at least one photoinitiator.
Dependencies are inferred from the claim text.