Biodegradable Hot Melt Adhesives
The present disclosure provides a hot melt adhesive which includes at least the following components: (1) from about 10 to about 20 weight percent of a lactic acid oligomer or polymer having a weight average molecular weight from about 1500 to about 3000; (2) from about 40 to about 75 weight percent of polylactide having a weight average molecular weight from about 10,000 to about 18,000; (3) from about 20 to about 35 weight percent of a polyester formed from the copolymerization of one or more diols and one or more dicarboxylic acids; and (4) from about 0.5 to about 5 weight percent of a copolymer of vinyl acetate and a mono-unsaturated short chain fatty acid, the fatty acid having from 4 to 12 carbon atoms. All of the aforementioned weight percentages are based on the overall weight of the hot melt adhesive. An adhesive-coated substrate and a method for applying a hot melt adhesive to a substrate are also disclosed.
1 . A hot melt adhesive comprising:
from about 10 to about 20 weight percent of a lactic acid oligomer or polymer having a weight average molecular weight from about 1500 to about 3000;
from about 40 to about 75 weight percent of polylactide having a weight average molecular weight from about 10,000 to about 18,000;
from about 20 to about 35 weight percent of a polyester formed from the copolymerization of one or more diols and one or more dicarboxylic acids; and
from about 0.5 to about 5 weight percent of a copolymer of vinyl acetate and a mono-unsaturated short chain fatty acid, the fatty acid having from 4 to 12 carbon atoms,
wherein all weight percentages are based on the overall weight of the hot melt adhesive.
2 . The hot melt adhesive of claim 1 , wherein the hot melt adhesive has a viscosity from about 1000 centipoise to about 6000 centipoise at a temperature of about 143° C.
3 . The hot melt adhesive of claim 1 , wherein the lactic acid oligomer or polymer has a viscosity from about 350 centipoise to about 450 centipoise at a temperature of about 280° C.
4 . The hot melt adhesive of claim 1 , wherein the polylactide has a viscosity from about 1800 centipoise to about 2200 centipoise at a temperature of about 143° C.
5 . The hot melt adhesive of claim 1 , wherein the polylactide further comprises a polymer capping group formed by reaction of the polylactide with a carboxylic acid or a carboxylic acid derivative.
6 . The hot melt adhesive of claim 1 , wherein the polyester has a viscosity from about 15,000 centipoise to about 35,000 centipoise at a temperature of about 216° C.
7 . The hot melt adhesive of claim 1 , wherein the polyester has a weight average molecular weight from about 55,000 to about 72,000.
8 . The hot melt adhesive of claim 1 , wherein the polyester further comprises a polymer capping group formed by reaction of the polylactide with a carboxylic acid or a carboxylic acid derivative.
9 . The hot melt adhesive of claim 1 , wherein the polyester is polybutylene(succinate-co-adipate) (“PB SA”).
10 . The hot melt adhesive of claim 1 , wherein the mono-unsaturated short chain fatty acid is crotonic acid.
11 . An adhesive-coated substrate comprising:
a substrate having at least a first side; and
a hot melt adhesive coating applied to at least of portion of the substrate first side, wherein the hot melt adhesive coating comprises
from about 10 to about 20 weight percent of a lactic acid oligomer or polymer having a weight average molecular weight from about 1500 to about 3000,
from about 40 to about 75 weight percent of polylactide having a weight average molecular weight from about 10,000 to about 18,000,
from about 20 to about 35 weight percent of a polyester formed from the copolymerization of one or more diols and one or more dicarboxylic acids, and
from about 0.5 to about 5 weight percent of a copolymer of vinyl acetate and a mono-unsaturated short chain fatty acid, the fatty acid having from 4 to 12 carbon atoms,
wherein all weight percentages are based on the overall weight of the hot melt adhesive.
12 . The adhesive-coated substrate of claim 11 , wherein the hot melt adhesive has a viscosity from about 1000 centipoise to about 6000 centipoise at a temperature of about 143° C.
13 . The adhesive-coated substrate of claim 11 , wherein the lactic acid oligomer or polymer has a viscosity from about 350 centipoise to about 450 centipoise at a temperature of about 280° C.
14 . The adhesive-coated substrate of claim 11 , wherein the polylactide has a viscosity from about 1800 centipoise to about 2200 centipoise at a temperature of about 143° C.
15 . The adhesive-coated substrate of claim 11 , wherein the polylactide further comprises a polymer capping group formed by reaction of the polylactide with a carboxylic acid or a carboxylic acid derivative.
16 . The adhesive-coated substrate of claim 11 , wherein the polyester has a viscosity from about 15,000 centipoise to about 35,000 centipoise at a temperature of about 216° C.
17 . The adhesive-coated substrate of claim 11 , wherein the polyester has a weight average molecular weight from about 55,000 to about 72,000.
18 . The adhesive-coated substrate of claim 11 , wherein the polyester further comprises a polymer capping group formed by reaction of the polylactide with a carboxylic acid or a carboxylic acid derivative.
19 . The adhesive-coated substrate of claim 11 , wherein the polyester is polybutylene(succinate-co-adipate) (“PB SA”).
20 . The adhesive-coated substrate of claim 11 , wherein the mono-unsaturated short chain fatty acid is crotonic acid.
21 . A method for making a hot melt adhesive, comprising the steps of:
melt blending, at a temperature from about 140 to about 175° C., a mixture which comprises
from about 10 to about 20 weight percent of a lactic acid oligomer or polymer having a weight average molecular weight from about 1500 to about 3000,
from about 40 to about 75 weight percent of polylactide having a weight average molecular weight from about 10,000 to about 18,000,
from about 20 to about 35 weight percent of a polyester formed from the copolymerization of one or more diols and one or more dicarboxylic acids, and
from about 0.5 to about 5 weight percent of a copolymer of vinyl acetate and a mono-unsaturated short chain fatty acid, the fatty acid having from 4 to 12 carbon atoms; and
further blending the mixture with from about 1 to about 5 weight percent of a carboxylic acid or a carboxylic acid derivative, at a temperature at a temperature from about 140 to about 175° C. to provide a stabilized hot melt adhesive,
wherein all weight percentages are based on the overall weight of the hot melt adhesive.
22 . The method of claim 21 , wherein the carboxylic acid or a carboxylic acid derivative comprises an acid anhydride.
23 . The method of claim 21 , wherein the polyester has a weight average molecular weight from about 55,000 to about 72,000.
24 . The method of claim 21 , wherein the polyester is polybutylene(succinate-co-adipate) (“PBSA”).
25 . The method of claim 21 , wherein the mono-unsaturated short chain fatty acid is crotonic acid.