Hot melt pressure sensitive adhesive and thermoset comprising styrene-butadiene polymers having high vinyl and high di-block
View Patent ↗The present invention provides methods and systems for a hot melt pressure sensitive adhesive and thermoset that comprises from about 5 to about 50 wt. % of a block copolymer, from about 0 to about 75 wt. % of a tackifying resin, from about 0 to about 45 wt. % of an oil, and from about 0 to about 3 wt. % of an antioxidant.
1. A hot melt pressure sensitive adhesive, comprising:
from about 20 to about 35 wt. % of a block copolymer composition comprising (i) a diblock copolymer comprising one block of a monovinylaromatic hydrocarbon, an A block, and one block of a conjugated diene, a B block, having a peak molecular weight from 30,000 to 78,000 and a vinyl content from 35 to 80 mol percent based on the number of repeat monomer units in the conjugated diene block, and (ii) a block copolymer comprising at least two blocks of monovinylaromatic hydrocarbon and at least one block of conjugated diene, the block copolymer selected from the group consisting of linear triblock copolymers having a peak molecular weight that is 1.5 to 3.0 times the peak molecular weight of the diblock copolymer, multiarm coupled block copolymers having a peak molecular weight that is 1.5 to 9.0 times the peak molecular weight of the diblock copolymer, and mixtures thereof, wherein each block copolymer has a vinyl content from 35 to 80 mol percent based on the number of repeat monomer units in the conjugated diene block, wherein the melt index for the block copolymer composition is from about 20 g/10 min. to about 35 g/10 min. as determined by ASTM D-1238, condition G (200° C., 5 kg) and wherein the ratio of (i) to (ii) in the block copolymer composition is greater than 1:1;
from about 30 to about 60 wt. % of a tackifying resin;
from about 0 to about 45 wt. % of an oil; and
from about 0 to about 3 wt. % of an antioxidant,
wherein said wt. % is based on the total weight of the hot melt pressure sensitive adhesive.
2. The hot melt pressure sensitive adhesive according to claim 1 , wherein the block copolymer (ii) has a polystyrene content (PSC) within a range of from about 10 to about 55 wt. %.
3. The hot melt pressure sensitive adhesive according to claim 1 , further comprising an unsaturated block copolymer.
4. The hot melt pressure sensitive adhesive according to claim 1 , wherein said oil is a paraffinic and/or naphthenic processing oil.
5. The hot melt pressure sensitive adhesive according to claim 1 , wherein the tackifying resin is compatible with the B block and is selected from the group consisting of C 5 hydrocarbon resins, hydrogenated C 9 hydrocarbon resins, rosin esters, and styrenated terpene resins.
6. The hot melt pressure sensitive adhesive according to claim 5 , wherein the tackifying resin is a rosin ester tackifier resin or a terpene tackifier resin.
7. The hot melt pressure sensitive adhesive according to claim 1 , wherein the tackifying resin is compatible with the A block and is selected from the group consisting of coumarone-indene rosin, polyindene resin, poly(methyl indene) resin, polystyrene resin, vinyltoluene-alphamethylstyrene resin, alphamethylstyrene resin and polyphenylene ether.
8. The hot melt pressure sensitive adhesive according to claim 1 , wherein the amount of block copolymer composition is from about 23 to about 32 wt. %.
9. The hot melt pressure sensitive adhesive according to claim 1 , wherein the oil is present in an amount of from about 10 to 35 wt. %.
10. The hot melt pressure sensitive adhesive according to claim 1 , wherein the block copolymer (ii) has a vinyl content of about 46 mol % to about 70 mol %.
11. The thermoset according to claim 1 , wherein the oil is a naphthenic processing oil present in an amount of from about 0 to about 10 wt. %.