Process of incorporating additives into vinylidene chloride polymers without the use of a blender
View Patent ↗Solid additive particles are added to solid vinylidene chloride (VDC) polymer particles by a process comprising the steps of: A. Polymerizing VDC monomer, optionally with one or more mono-ethylenically unsaturated comonomers, in a polymerization zone under polymerization conditions to form solid VDC polymer particles; B. Stopping the polymerization of the VDC monomers after formation of the solid VDC polymer particles; and C. Contacting the solid VDC polymer particles with the solid additive particles (i) before the solid VDC polymer particles are de-watered, and (ii) at a temperature sufficient to melt or soften the solid additives particles but insufficient to melt or soften the solid VDC polymer particles such that the melted or softened solid additive particles adhere to the solid VDC polymer particles upon contact.
1. A process for blending solid additive particles with solid VDC polymer particles, the process comprising the steps of:
A. Polymerizing VDC monomer, optionally with one or more mono-ethylenically unsaturated comonomers, in a polymerization zone under polymerization conditions to form solid VDC polymer particles;
B. Stopping the polymerization of the VDC monomers after formation of the solid VDC polymer particles; and
C. Contacting the solid VDC polymer particles with the solid additive particles (i) before the solid VDC polymer particles are de-watered, (ii) during and/or after stripping residual monomer from the solid VDC polymer particles, and (iii) at a temperature sufficient to melt or soften the solid additives particles but insufficient to melt or soften the solid VDC polymer particles such that the melted or softened additive particles adhere to the solid VDC polymer particles upon contact.
2. The process of claim 1 in which the solid additive particles are contacted with the solid VDC polymer particles in a residual monomer stripper zone.
3. The process of claim 2 in which the residual monomer stripper zone is separate and apart from the polymerization zone.
4. The process of claim 1 in which the solid additive particles are contacted with the solid VDC polymer particles after the residual monomer is separated from the solid VDC polymer particles.
5. The process of claim 1 in which the solid additive particles are contacted with the solid VDC polymer particles while the residual monomer is separated from the solid VDC polymer particles.
6. The process of claim 1 in which the contacting of Step C is at a temperature of 60 to 120° C.
7. The process of claim 6 in which the solid additive particles are of about the same size or smaller than the size of the VDC polymer particles.
8. The process of claim 7 in which the solid additive particles comprise a mixture of two or more additives.
9. The process of claim 8 in which the solid additive particles comprise at least one of an antioxidant, light stabilizer, pigment, processing aid, lubricant, acid scavenger and wax.
10. The process of claim 9 in which the solid additive particles are contacted with the solid VDC polymer particles in an amount of greater than zero to less than 10 wt % based on the combined weight of the solid VDC and solid additive particles.
11. The process of claim 1 , wherein VDC monomer is polymerized in a reaction vessel, and wherein the solid additive particles are contacted with the solid VDC polymer particles in the reaction vessel.
12. The process of claim 1 , wherein VDC monomer is polymerized in a reaction vessel, and wherein the solid additive particles are contacted with the solid VDC polymer particles in a second vessel.