A process for forming voided latex particles is improved by combining swelling and polymerization of an outer shell into a single step. The process includes contacting multi-stage emulsion polymer particles comprising a core, at least one intermediate shell, with a swelling agent, and polymerizing an outer shell after said contacting with swelling agent wherein the core and the at least one intermediate shell are contacted with swelling agent in the presence of less than 0.5% monomer based on the weight of the multi-stage emulsion polymer particles, and substantially all of the swelling occurs during polymerization of the outer shell.

A process for forming voided latex particles is improved by combining swelling and polymerization of an outer shell into a single step. The process includes contacting multi-stage emulsion polymer particles comprising a core, at least one intermediate shell, with a swelling agent, and polymerizing an outer shell after said contacting with swelling agent wherein the core and the at least one intermediate shell are contacted with swelling agent in the presence of less than 0.5% monomer based on the weight of the multi-stage emulsion polymer particles, and substantially all of the swelling occurs during polymerization of the outer shell.

A process for forming voided latex particles is improved by combining swelling and polymerization of an outer shell into a single step. The process includes contacting multi-stage emulsion polymer particles comprising a core, at least one intermediate shell, with a swelling agent, and polymerizing an outer shell after said contacting with swelling agent wherein the core and the at least one intermediate shell are contacted with swelling agent in the presence of less than 0.5% monomer based on the weight of the multi-stage emulsion polymer particles, and substantially all of the swelling occurs during polymerization of the outer shell.

A process for forming voided latex particles is improved by combining swelling and polymerization of an outer shell into a single step. The process includes contacting multi-stage emulsion polymer particles comprising a core, at least one intermediate shell, with a swelling agent, and polymerizing an outer shell after said contacting with swelling agent wherein the core and the at least one intermediate shell are contacted with swelling agent in the presence of less than 0.5% monomer based on the weight of the multi-stage emulsion polymer particles, and substantially all of the swelling occurs during polymerization of the outer shell.

A process for forming voided latex particles is improved by combining swelling and polymerization of an outer shell into a single step. The process includes contacting multi-stage emulsion polymer particles comprising a core, at least one intermediate shell, with a swelling agent, and polymerizing an outer shell after said contacting with swelling agent wherein the core and the at least one intermediate shell are contacted with swelling agent in the presence of less than 0.5% monomer based on the weight of the multi-stage emulsion polymer particles, and substantially all of the swelling occurs during polymerization of the outer shell.

A process for forming voided latex particles is improved by combining swelling and polymerization of an outer shell into a single step. The process includes contacting multi-stage emulsion polymer particles comprising a core, at least one intermediate shell, with a swelling agent, and polymerizing an outer shell after said contacting with swelling agent wherein the core and the at least one intermediate shell are contacted with swelling agent in the presence of less than 0.5% monomer based on the weight of the multi-stage emulsion polymer particles, and substantially all of the swelling occurs during polymerization of the outer shell.

The present invention relates to a method of preparing a vinyl chloride polymer having good thermal stability due to the restraint of dehydrochlorination by heat or ultraviolet rays, and a vinyl chloride polymer prepared thereby. In the preparation method through bulk polymerization, a modifier is introduced to a polymerization process to impart the vinyl chloride polymer with high thermal stability without inducing modification. Therefore, the preparation method via the bulk polymerization of the vinyl chloride polymer and the vinyl chloride polymer prepared thereby according to the present invention may be readily applied to industries requiring thereof such as industries concerning a vinyl chloride resin and the molded article thereof.

The present invention relates to a method of preparing a vinyl chloride polymer having good thermal stability due to the restraint of dehydrochlorination by heat or ultraviolet rays, and a vinyl chloride polymer prepared thereby. In the preparation method through bulk polymerization, a modifier is introduced to a polymerization process to impart the vinyl chloride polymer with high thermal stability without inducing modification. Therefore, the preparation method via the bulk polymerization of the vinyl chloride polymer and the vinyl chloride polymer prepared thereby according to the present invention may be readily applied to industries requiring thereof such as industries concerning a vinyl chloride resin and the molded article thereof.

Methods according to the present invention decolorize a polymer by mixing a solution of the polymer with a photocatalyst and exposing the mixture to ultraviolet light; by way of non-limiting example, the polymer may be a star polymer and the photocatalyst may be titanium dioxide. Methods according to the present invention also utilize a metal scavenger, in some embodiments a solid-phase metal scavenger, to remove a metal catalyst from a polymer solution; by way of non-limiting example, the metal catalyst may be a tin catalyst. The decolorization methods and the catalyst removal methods of the present invention may be practiced separately, sequentially in any order, or simultaneously.

A new and efficient toxicity and/or odor reducing method for ethyl acrylate and/or acrylonitrile containing aqueous polymer dispersion is disclosed, which comprises contacting a sufficient amount of an ethyl acrylate/acrylonitrile scavenging compound with a stable aqueous dispersion of a polymer to form a polymeric dispersion that contains less than 1 ppm of ethyl acrylate and less than 1 ppm acrylonitrile; wherein the polymer contains a) polymerized units of acylonitrile and/or ethyl acrylate and b) at least 5 ppm of ethyl acrylate and/or acrylonitrile monomers; and wherein the ethyl acrylate/acrylonitrile scavenging compound are contacted with the dispersion independently from contact of the dispersion with any redox pairs.