Rubber modified styrenic copolymers and their use in disposable card applications
A thermoplastic sheet that includes a continuous phase and a dispersed phase, where A) the continuous phase contains a polymer composition resulting from the polymerization of a monomer mixture containing a styrenic monomer and an alkyl (meth)acrylate monomer in the presence of the dispersed phase; and B) the dispersed phase contains one or more block copolymer selected from diblock and triblock copolymers of styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene, styrene-isoprene-styrene, partially hydrogenated styrene-isoprene-styrene. The thermoplastic sheet is formed by extruding a thermoplastic composition that is cut to desired dimensions to form thermoplastic items, e.g. identification cards, credit cards, bank cards, key cards, gift cards, phone cards, playing cards, menus, and the like. Indicia and/or printing can be applied to the items to provide for commercial applications. The sheet may be opaque or may be relatively clear to transparent with a Haze value of 0.01% up to 10%.
1. A rectangular card made according to a method comprising:
extruding a thermoplastic composition to form a thermoplastic sheet, wherein the thermoplastic composition comprises a continuous phase and a dispersed phase, wherein
A) the continuous phase comprises a polymer composition resulting from the polymerization of a monomer mixture comprising (i) from about 25 to 75 parts by weight of a styrenic monomer and (ii) from about 25 to 75 parts by weight of an alkyl(meth)acrylate monomer, wherein the alkyl group is a C 1 to C 12 linear, branched or cyclic alkyl group, in the presence of the dispersed phase; and
B) the dispersed phase comprises from about 2 to about 50 parts by weight of one or more block copolymers selected from the group consisting of diblock and triblock copolymers of styrene-butadiene, styrene-butadiene-styrene, styrene-isoprene, styrene-isoprene-styrene, partially hydrogenated styrene-isoprene-styrene, for a total of 100 parts by weight of the combination of A) and B);
optionally surface treating the extruded sheet;
cuffing the sheet to form a smaller sheet of desired dimensions;
printing on a surface of the smaller sheet;
optionally cutting the smaller sheet to desired item dimensions; and
optionally laminating the item;
wherein the card is formed so that a portion of the
thermoplastic composition is raised above a plane of the card to form characters.
2. The card according to claim 1 , wherein the characters are in the form of numbers and/or letters.
3. The card according to claim 1 , wherein the dispersed phase B) is present as discrete particles dispersed within the continuous phase A).
4. The card according to claim 3 , wherein the volume average particle size of the dispersed phase B) is from about 0.1 μm to about 2 μm.
5. The card according to claim 1 , wherein the difference between the refractive index of the continuous phase A) and the dispersed phase B) is not more than 0.01.
6. The card according to claim 1 , wherein the styrenic monomer is selected from the group consisting of styrene, p-methyl styrene, tertiary butyl styrene, dimethyl styrene, nuclear brominated or chlorinated derivatives thereof and combinations thereof.
7. The card according to claim 1 , wherein the alkyl(meth)acrylate monomer comprises methylmethacrylate and optionally butyl acrylate.
8. The card according to claim 1 , wherein the block copolymer has a weight average molecular weight of not less than about 75,000.
9. The card according to claim 1 , wherein the block copolymer is a linear or radial block copolymer.
10. The card according to claim 1 , wherein the block copolymer is a triblock styrene-butadiene-styrene or styrene-isoprene-styrene copolymer having a weight average molecular weight of from about 175,000 to about 275,000.
11. The card according to claim 1 , wherein at least some of the polymers in A) are grafted onto the block copolymer in B).
12. The card according to claim 1 , having a thickness of from about 0.05 mm to about 5 mm.
13. The card according to claim 1 , wherein the card is an opaque card further comprising pigments or colorants or both.
14. The card according to claim 1 , wherein the card is an opaque card further comprising one or more additives selected from the group consisting of lubricants, fillers, light stabilizers, heat stabilizers, surface active agents, and combinations thereof.
15. The card according to claim 1 , wherein the monomer mixture further comprises a chain transfer agent.
16. The card according to clam 1 , having a first dimensional length of from about 2 cm to about 15 cm, a second dimension of from about 1 cm to about 12 cm and a thickness of from about 0.05 mm to about 5 mm.