FILMS AND FILM LAMINATES WITH RELATIVELY HIGH MACHINE DIRECTION MODULUS
Films and film laminates include a blend of polymers, the blend including an elastomeric block copolymer in an amount from about 51% to about 95% by weight of the blend; and a polystyrenic polymer in an amount from about 1% to about 25% of the weight of the blend, wherein the polystyrenic polymer is selected from the group consisting of polystyrenic homopolymers and polystyrenic random interpolymers. The films and laminates are elastic in the cross machine direction and have a relatively high modulus, or stiffness, in the machine-direction.
1 . A film comprising a blend of polymers, the blend comprising
An elastomeric block copolymer containing a styrene block portion having a number average molecular weight or at least about 5,000 Daltons, the elastomeric block copolymer being present in an amount from about 51% to about 95% by weight of the blend; and
a polystyrenic polymer having a number average molecular weight of at least about 5000 Daltons, the polystrenic polymer being present in an amount from about 1% to about 25% by weight of the blend, the number average molecular weight of the polystyrenic polymer being at least about 10 percent greater than the number average molecular weight of the styrene block portion of the elastomeric block copolymer, and wherein the polystyrenic polymer is selected from the group consisting of polystyrenic homopolymers and polystyrenic random interpolymers.
2 . The film of claim 1 , wherein the film has a percent elongation at 500 psi from about 1 to about 80% in a machine direction.
3 . The film of claim 1 , wherein the film has a percent elongation at 500 psi from about 100% to about 500% in a cross machine direction.
4 . The film of claim 1 , wherein the elastomeric block copolymer is a styrenic block copolymer.
5 . The film of claim 1 , wherein the polystyrenic polymer is selected from the group consisting of polymers of styrene, alkyl ring-substituted styrenes, aryl ring-substituted styrenes, polystyrenic monomers, phenyl maleimide, and combinations thereof.
6 . The film of claim 1 , wherein the polystyrenic polymer is a homopolymer.
7 . The film of claim 1 , wherein the film can be stretched by at least about 100% in the cross machine direction.
8 . The film of claim 1 , wherein the film can retract at least 50% after being stretched to 100% in the cross-direction.
9 . The film of claim 1 , wherein the film exhibits a ratio of percent elongation at 500 psi in the cross machine direction to percent elongation at 500 psi in the machine direction of about 5 to about 50.
10 . A film laminate, comprising:
a film comprising a blend of polymers, the blend comprising
an elastomeric block copolymer containing a styrene block portion having a number average molecular weight or at least about 5,000 Daltons, the elastomeric block copolymer being present in an amount from about 51% to about 95% by weight of the blend;
a polystyrenic polymer having a number average molecular weight of at least about 5000 Daltons, the polystrenic polymer being present in an amount from about 1% to about 25% by weight of the blend, the number average molecular weight of the polystyrenic polymer being at least about 10 percent greater than the number average molecular weight of the styrene block portion of the elastomeric block copolymer, and wherein the polystyrenic polymer is selected from the group consisting of polystyrenic homopolymers and polystyrenic random interpolymers; and
a nonwoven material attached to the film.
11 . The film laminate of claim 10 , wherein the film laminate can be stretched by at least about 100% in a cross machine direction.
12 . The film laminate of claim 10 , wherein the film laminate has a percent elongation at 500 psi from about 1 to about 80% in a machine direction.
13 . The film laminate of claim 10 , wherein the film laminate has a percent elongation at 500 psi from about 100% to about 500% in a cross machine direction.
14 . The film laminate of claim 10 , wherein the elastomeric block copolymer is a styrenic block copolymer.
15 . The film laminate of claim 10 , wherein the polystyrenic polymer is selected from the group consisting of polymers of styrene, alkyl ring-substituted styrenes, aryl ring-substituted styrenes, polystyrenic monomers, phenyl maleimide, and combinations thereof.
16 . The film laminate of claim 10 , wherein the polystyrenic polymer is a homopolymer.
17 . The film laminate of claim 10 , wherein the film laminate can retract at least 50% when stretched to 100% in the cross machine direction.
18 . The film laminate of claim 10 , wherein the film laminate exhibits a ratio of percent elongation at 500 psi in the cross machine direction to percent elongation at 500 psi in the machine direction of about 5 to about 50.
19 . A method of producing a film having a relatively high modulus in a machine direction, the method comprising the steps of:
blending an elastomeric block copolymer and a polystyrenic polymer selected from the group consisting of polystyrenic homopolymers and polystyrenic random interpolymers to form a blend, the blend comprising the elastomeric block copolymer in an amount from about 51% to about 95% by weight of the blend, and the polystyrenic polymer in an amount from about 1% to about 25% by weight of the blend, the elastomeric block copolymer containing a styrene block portion having a number average molecular weight or at least about 5,000 Daltons, the polystyrenic polymer having a number average molecular weight of at least about 5000 Daltons, the number average molecular weight of the polystyrenic polymer being at least about 10 percent greater than the number average molecular weight of the styrene block portion of the elastomeric block copolymer, and
extruding the blend to form a film.
20 . The method of claim 19 further comprising the step of cross-linking the elastomeric block copolymer.
21 . The method of claim 19 , wherein the polystyrenic polymer comprises a homopolymer.
22 . A personal care product comprising the film of claim 1 .