Processes for preparing non-gelling high polymer compositions and thermoplastic blends thereof

Disclosed are compositions and processes for preparing polymeric materials having polymerizable units derived from at least one C.sub.8 to C.sub.30 alkyl (meth)acrylate monomer, and at least one chain branching unit. The presence of the chain branching unit suprisingly results in the polymeric composition having non-gelled polymer chains. The polymeric compositions are useful as additives for improving the melt strength of thermoplastic resins.

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What is claimed is:

1. A process for preparing an aqueous dispersion of polymer particles comprising a polymeric composition having non-gelled polymer chains, said process comprising the stepsof: a) preparing an aqueous emulsion of hydrophobic monomer droplets, said droplets comprising: i) at least one C.sub.8 to C.sub.30 alkyl (meth)acrylate monomer, ii) at least one chain branching monomer, said chain branching monomer present in an amountnot greater than 0.10 weight percent based on total weight of the C.sub.8 to C.sub.30 alkyl (meth)acrylate monomer, iii) at least one monomer transport aid, and (iv) at least one emulsifier; and b) polymerizing, by at least one technique selected fromthe group consisting of conventional emulsion polymerization bulk polymerization and solution polymerization, said C.sub.8 to C.sub.30 alkyl (meth)acrylate monomer with said at least one chain branching monomer using at least one free radical initiatorto form said aqueous dispersion of polymer particles comprising a polymeric composition having non-gelled polymer chains, wherein said polymeric composition has a weight average molecular weight of at least 100,000 g/mol.

2. The process according to claim 1, further comprising the step of reducing the amount of unpolymerized monomers using at least one of the following: t-alkyl hydroperoxide, t-alkyl peroxide, and t-alkyl perester, wherein the t-alkyl groupincludes at least 5 carbon atoms; and optionally at least one other oxidant.

3. The process according to claim 1, wherein said aqueous emulsion of hydrophobic monomer droplets is prepared using high shear means to provide a mean droplet diameter of less than 30 microns.

4. The process according to claim 1, wherein said at least one monomer transport aid comprises cyclodextrin.

5. The process according to claim 1, wherein said polymerizing step is performed to produce said polymer particles which comprise at least one soft phase, which comprises said polymeric composition having non-gelled polymer chains, and at leastone hard phase, said at least one hard phase having a glass transition temperature of at least 25.degree. C.

6. The process according to claim 5, wherein said at least one hard phase is selected from the group consisting of at least one hard polymer shell disposed externally to each of said polymer particles, a plurality of hard polymer particles, andcombinations thereof.

7. The process according to claim 6, wherein said polymerizing step comprises forming by polymerization a plurality of soft polymer particles, comprising said polymeric composition having non-gelled polymer chains, as said at least one softphase in said aqueous dispersion of polymer particles, and adding to said aqueous dispersion of polymer particles a plurality of hard polymer particles as said at least one hard phase.

8. The process according to claim 6, wherein said polymerizing step further comprises at least one technique selected from the group consisting of polymerization, multistaged polymerization and agglomeration, to form said polymer particleswherein each of said polymer particles comprises at least one core as said soft phase and at least one shell as said at least one hard phase.

9. The process according to claim 8, wherein said polymerizing step comprises multi staged polymerization wherein said C.sub.8 to C.sub.30 alkyl (meth)acrylate monomer are polymerized with said at least one chain branching monomer to form saidat least one core of each of said polymer particles and at least one ethylenically unsaturated monomer is polymerized in the presence of said at least one core to form said at least one shell externally on each of said polymer particles.

10. The process according to claim 9, wherein said polymerizing step comprises polymerizing said C.sub.8 to C.sub.30 alkyl (meth)acrylate monomer with said at least one chain branching monomer to form said at least one core of each of saidpolymer particles, and polymerizing at least one ethylenically unsaturated monomer in the presence of said at least one core to form an inner polymer shell adjacent to each of said at least one core, forming a plurality of core-and-inner-shell-particles,and polymerizing at least one ethylenically unsaturated monomer in the presence of said plurality of core-and-inner-shell particles to form an outer polymer shell situated externally to said inner polymer shell of each of said particles, whereby said atleast one shell comprises said inner polymer shell and said outer polymer shell, wherein said inner polymer shell is situated adjacent to said at least one core of each of said polymer particles, and said outer polymer shell is situated external to saidinner polymer shell.

11. The process according to any one of claims 1, 2-4 and 5-10, further comprising at least one step to remove water from said aqueous dispersion of polymer particles, so that said polymer particles are in the form of at least one of thefollowing: a wetcake, powder, tablet, pellet, bead, film, and extrudate.