Tie-layer adhesives for styrene polymers and articles
View Patent ↗Adhesive compositions for styrene polymers are provided. The adhesives are suitable for use as tie-layers in multi-layer films and sheets and comprise a polyolefin base resin, a functionalized polyolefin and a combination of styrene triblock copolymers.
1. An adhesive composition comprising:
(a) 50 to 60 wt. % of an ethylene-butene-1 copolymer having a density from 0.916 to 0.919 g/cm 3 and a melt index from 1.5 to 3 g/10 min, wherein the ethylene-butene-1 copolymer contains a hard phase and a soft rubber phase;
(b) 5 to 20 wt. % of a high density polyethylene has a density of about 0.955 g/cm 3 and grafted with 0.75 to 2.5 wt. % maleic anhydride maleic anhydride, and wherein (b) has a melt index from 2.5 to 15 g/10 min, as measured at 190° C., 2.16 kg; and
(c) 25 to 40 wt. % of a mixture comprising a styrene-isoprene-styrene triblock copolymer and styrene-butadiene-styrene triblock copolymer,
wherein the styrene-isoprene-styrene triblock copolymer and the styrene-butadiene-styrene triblock copolymer are present at a weight ratio from 5:1 to 1:5,
wherein the mixture comprises 30 to 55 wt. % styrene derived units, and
wherein the mixture has a melt index from 10 to 50 g/10 min measured at 200° C./5 kg;
(d) an additive comprising
a stabilizer comprising a hindered phenol and phosphite at a weight ratio of 1:1;
wherein the adhesive composition is characterized by an adhesion value as measured in accordance with ASTM D 1876-93 of 2.34 lbs/in when bonded to two styrene polymer layers.
2. The adhesive composition of claim 1 wherein the weight ratio of styrene-isoprene-styrene triblock copolymer to styrene-butadiene-triblock copolymer is 1.5:1 to 1:1.5.
3. The adhesive composition of claim 1 wherein the mixture of the styrene-isoprene-styrene triblock copolymer and the styrene-butadiene-styrene triblock copolymer has a melt index from 20-45 g/10 min.
4. The adhesive composition of claim 1 wherein the styrene-isoprene-styrene triblock copolymer and the styrene-butadiene-styrene triblock copolymer are present in a weight ratio from 1:1.
5. The composition of claim 1 wherein the stabilizer is at a level ranging from about 250 to about 5000 ppm.
6. An adhesive composition consisting essentially of:
(a) 59.8 wt. % ethylene-butene-1 copolymer having a density of about 0.918 g/cm 3 , wherein the ethylene-butene-1 copolymer contains a hard phase and a soft rubber phase;
(b) 10 wt. % high density polyethylene having a density of about 0.955 g/cm 3 grafted with about 1.9 wt. % maleic anhydride, wherein (b) has a melt index from 2.5 to 15 g/10 min, as measured at 190° C., 2.16 kg; and
(c) 30 wt. % styrene-isoprene-styrene triblock copolymer and styrene-butadiene-styrene triblock copolymer, wherein the styrene-isoprene-styrene triblock copolymer and the styrene-butadiene-styrene triblock copolymer are present at a weight ratio from 1:1; and
(e) a stabilizer present at 0.2 wt. %;
wherein the adhesive composition is characterized by an adhesion value as measured in accordance with ASTM D 1876-93 of 2.34 lbs/in when bonded to two styrene polymer layers.