Melt-stable polylactide resin compositions containing phosphite esters
AssigneeNatureWorks LLC
InventorsJed Richard Randall, Samantha Leigh Thompson-Barclay, Patricia America Nancy Popescu, Patrick Kevin Hoard, Joseph David Schroeder, James Russell Valentine, Manuel A.W. Natal
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Abstract
Polylactide resin compositions contain certain phosphite esters. The presence of the phosphite ester increases the rate of hydrolysis of the polylactide resin under conditions of moisture (including atmospheric moisture) at mildly elevated temperatures.
Claims17
A polylactide resin composition comprising (a) at least one polylactide having a number-average molecular weight as measured by gel permeation chromatography against a polystyrene standard of at least 20,000 g/mol, the polylactide containing (i) 5 to 300 ppm by weight of Group 2-14 metals based on the weight of the polylactide, (ii) 0.1 to 2 parts by weight per 100 parts by weight of the polylactide of (ii-a) a polymer having multiple carboxylic acid, a number average molecular weight of at least 500 g/mol and at least one carboxylic acid group per 250 atomic mass units and/or (ii-b) a polyphosphoric acid which may be partially or completely neutralized, and/or residue thereof and (iii) no more than 0.6 parts by weight of lactide per 100 parts by weight of the polylactide, and (b) at least one phosphite ester compound having a number-average molecular weight of up to 5,000 g/mol, the phosphite ester compound containing 3 to 15% by weight phosphorus and wherein the phosphite ester compound contains, per phosphite phosphorus atom, from zero to one aryl group in which at least one ring carbon ortho to a ring carbon bonded directly to a phosphite oxygen is directly bonded to a tertiary carbon atom of a substituent group, and the polylactide resin composition containing sufficient phosphite ester compound to provide 0.01 to 32 g of phosphorus per kilogram of the polylactide in the polylactide resin composition.
The method of 7 wherein in step b) the crude PLA resin is combined with the polyphosphoric acid.
A polylactide resin composition comprising (a) at least one polylactide having a number-average molecular weight as measured by gel permeation chromatography against a polystyrene standard of at least 20,000 g/mol having dissolved or dispersed therein (b) at least one polyphosphite ester compound containing 3.5 to 15% by weight phosphorus and being represented by either of structures I and II, wherein structure I is
- wherein each R2, R3, R4 and R5 can be the same or different and independently selected from the group consisting of C1-20 alkyl, C3-22 alkenyl, C6-40 cycloalkyl, C7-40 cycloalkylene, C1-20 methoxy alkyl glycol ethers, C1-20 alky glycol ethers, and/or Y—OH;
- Y is selected from the group consisting of C2-40 alkylene, C2-40 alkyl lactone, —R6—N(R7)—R8— wherein R6, R7, and R8 are independently selected from the group consisting of hydrogen, C1-20 alkyl, C3-22 alkenyl, C6-40 cycloalkyl, C7-40 cycloalkylene, C1-20 methoxy alkyl glycol ethers, C1-20 alky glycol ethers and/or Y—OH, m is an integral value ranging from 2 to 100 and x is an integral value ranging from 1 to 1000;
- and structure II is
- wherein R10, R11, R12, R13 and R14 can be the same or different are independently selected from the group consisting of C1-20 alkyl, C2-22 alkenyl, C6-40 cycloalkyl and C704o cycloalkenyl;
- Y is selected from the group consisting of C2-40 alkylene, C2-40 aliphatic carboxylic acid esters and C3-40 cycloalkylenes, n is a number from 5 to 100, u is a number from 8 to 1000, v is a number from 1 to 1000 and w is a number from 1 to 1000,
- is (i) a linear or branched C2 to C24 alkylene group;
- (ii) a residue, after removal of hydroxyl groups, of a glycol ether or a glycol polyether, a homopolymer or copolymer of ethylene glycol, and/or propylene glycol having 4 or more ether units and formula weights (after removal of hydroxyl groups) of up to 1000 g/mol;
- and (iii) an o-, m-, or p-dialkyl cyclohexane, in which the alkyl groups have 1 to 4 carbon atoms.
Dependencies are inferred from the claim text.