Agglomerated rubber particles and method of preparing
View Patent ↗A synthetic latex composition, comprising rubber particles, natural surfactants, a novel acid stable surfactant and water for use in agglomeration processes. The invention is also directed to a reproducible method for preparing agglomerated latex particles to control and achieve particle size targets within a specified range and distribution, by utilizing the inventive latex composition and process conditions, but without the use of elevated temperature, pressurization or mechanical agitation of prior art processes.
1. A method for agglomerating rubber particles, comprising:
a. providing a latex emulsion formulated with a natural surfactant;
b. adding an additional surfactant additive that is acid stable to the latex emulsion to form a mixture, wherein the acid stable surfactant comprises either sodium dodecyl benzene sulfonate or a naphthalene sulfonic acid condensate polymer, with formaldehyde functionality, ammonium salt;
c. reducing the pH of the mixture to a range of about 5.0 to 3.5 by addition of an acid, wherein the acid comprises phosphoric acid, polyphosphoric acid, sulfuric acid, sulfurous acid, hydrochloric acid, or acetic acid;
d. allowing the pH-reduced mixture to sit at room temperature with no agitation for a set period of time so that agglomerated rubber particles are formed; and
e. stabilizing the agglomerated rubber particles with a base.
2. The method as set forth in claim 1 , wherein the acid is phosphoric acid or acetic acid.
3. The method as set forth in claim 1 wherein the natural surfactant is potassium oleate, potassium rosinate or potassium dimerate.
4. The method as set forth in claim 1 wherein the acid stable surfactant is sodium dodecylbenzene sulfonate.
5. The method as set forth in claim 1 wherein the acid stable surfactant is a naphthalene sulfonic acid condensate polymer, with formaldehyde functionality, ammonium salt.
6. A method for agglomerating rubber particles, comprising:
a. providing a latex emulsion formulated with a natural surfactant, wherein the latex emulsion comprises a polymeric compound that is a homopolymer or copolymer of a 1,3-diene rubber, ethylene-propylene-diene terpolymer, acrylate-diene interpolymer rubber, polyisoprene rubber, or mixtures thereof;
b. adding an additional surfactant that is acid stable to the latex emulsion to form a mixture, wherein the additional surfactant comprises either sodium dodecyl benzene sulfonate or a naphthalene sulfonic acid condensate polymer, with formaldehyde functionality, ammonium salt;
c. reducing the pH of the mixture to a range of about 5.0 to 3.5, by adding an acid, wherein the acid comprises phosphoric acid, polyphosphoric acid, sulfuric acid, sulfurous acid, hydrochloric acid, or acetic acid;
d. allowing the pH-reduced mixture to sit at room temperature with no application of pressure or agitation for a set period of time for agglomeration of rubber particles; and
e. stabilizing the agglomerated rubber particles with a base.
7. The method as set forth in claim 6 , wherein the polymeric compound is butadiene, isoprene, chloroprene, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyltoluene, or vinylpyridine.
8. A method for agglomerating rubber particles, comprising:
a. providing a butadiene latex emulsion formulated with a natural surfactant, wherein the natural surfactant is potassium oleate, potassium rosinate or potassium dimerate;
b. adding an acid stable surfactant that is a naphthalene sulfonic acid condensate polymer, with formaldehyde functionality, ammonium salt to the latex emulsion to form a mixture;
c. reducing the pH of the mixture to about 4.5 to 3.0 by adding phosphoric acid or acetic acid;
d. allowing the pH-reduced mixture to sit at room temperature with no application of pressure or agitation for a set period of time for agglomeration of rubber particles; and
e. stabilizing the agglomerated butadiene particles with a base.
9. An agglomerated rubber particle product made by the method of claim 8 .
10. An agglomerated rubber particle product made by the method of claim 6 .