Stabilized polymer compositions and methods of making same

A method for preparing a stabilized polymer composition, the stabilized polymer composition comprising:

• a polymer selected from the group consisting of a polyolefin, a styrenic polymer, a poly(meth)acrylate, and combinations thereof;
• and
• about 50 parts per million (ppm) to about 20,000 ppm of a stabilizer composition, comprising:
• (a) about 1 wt % to about 60 wt % based on the total weight of the stabilizer composition of an antacid which does not fall under the compounds of (b), selected from the group consisting of metal oxides, metal hydroxides, metal carbonates, metal bicarbonates, natural hydrotalcites, synthetic hydrotalcites, natural hydrocalumites, synthetic hydrocalumites, pyrocatecholates, zeolites, silicates, and combinations thereof;
• (b) about 10 wt % to about 69 wt % based on the total weight of the stabilizer composition of an organic acid-metal salt having a general formula M1Ym,
• wherein M1 is selected from the group consisting of bismuth, calcium, zinc, magnesium, lithium, sodium, potassium, barium, strontium, aluminum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and combinations thereof;
• wherein Y is a conjugate base of an organic acid, having from six to twenty-four carbon atoms, selected from the group consisting of a linear or branched organic acid, a saturated or unsaturated organic acid, a substituted or unsubstituted organic acid, an aliphatic organic acid, an aromatic organic acid, an alicyclic organic acid, an oxygen-containing heterocyclic organic acid, dicarboxylic acid, polyprotic carboxylic acids, and combinations thereof;
• and
• wherein m is an integer from 1 to 3;
• and
• (c) about 30 wt % to about 89 wt % based on the total weight of the stabilizer composition of a primary antioxidant selected from the group consisting of sterically hindered phenolic compounds, hindered amine compounds, hydroxylamine compounds, and combinations thereof;
• wherein the stabilized polymer composition is free or substantially free of phosphite and phosphonite stabilizers;
• and
• wherein the method for preparing the stabilized polymer composition comprises:
• (1) preparing a first premixture comprising the antacid (a) and the organic acid-metal salt (b) or the primary antioxidant (c) or both;
• (2) intimately mixing the first premixture obtained from step (1) at an elevated temperature sufficient to provide a molten mixture comprising a dispersion of the antacid (a) in the organic acid-metal salt (b) or the primary antioxidant (c) or both;
• (3) optionally, lowering a temperature of the molten mixture to provide a second premixture in solid form;
• and
• (4) combining the molten mixture of step (2) or the second premixture in solid form of step (3) with the polymer and at least one additional ingredient of (b) or (c), if not already present.