Crosslinked polyolefin foam sheet with exceptional softness, haptics, moldability, thermal stability and shear strength

Patent metadata

Field	Value
Publication number	US-2016102186-A1
Application number	US-201514976072-A
Country	US
Kind code	A1
Filing date	Dec 21, 2015
Priority date	Jul 14, 2009
Publication date	Apr 14, 2016
Grant date	—

Abstract

A method of making a foam composition includes blending a composition including (i) about 15 to about 75 parts by weight of an olefin block copolymer with a controlled block sequence having a melt flow index of about 0.1 to about 15 grams per 10 minutes at 190° C. and a melting temperature of at least about 115° C., (ii) about 25 to about 85 parts by weight of at least one polypropylene based polymer having a melt flow index from about 0.1 to about 25 grams per 10 minutes at 230° C., (iii) a crosslinking monomer and (iv) a chemical blowing agent to produce a blended composition; crosslinking the blended composition to obtain a crosslinked composition having a crosslinking degree of about 20 to about 75%; and foaming the crosslinked composition at an elevated temperature to obtain a foam composition having a density of about 20 to about 250 kg/m 3 .

First claim

What is claimed is:

1 . A method of making a foam composition comprising:
a) blending a composition comprising (i) about 15 to about 75 parts by weight of an olefin block copolymer with a controlled block sequence having a melt flow index of about 0.1 to about 15 grams per 10 minutes at 190° C. and a melting temperature of at least about 115° C., (ii) about 25 to about 85 parts by weight of at least one polypropylene based polymer having a melt flow index from about 0.1 to about 25 grams per 10 minutes at 230° C., (iii) a crosslinking monomer and (iv) a chemical blowing agent to produce a blended composition; b) crosslinking the blended composition to obtain a crosslinked composition having a crosslinking degree of about 20 to about 75%; and c) foaming the crosslinked composition at an elevated temperature to obtain a foam composition having a density of about 20 to about 250 kg/m 3 .

2 . The method of claim 1 , wherein the foam composition has a compressive strength and density selected from the group consisting of:
a) a compressive strength of less than about 0.35 kg f /cm 2 and a density of less than about 40 kg/m 3 ; b) a compressive strength of less than about 0.51 kg f /cm 2 and a density of about 40 to about 59 kg/m 3 ; c) a compressive strength of less than about 0.66 kg f /cm 2 and a density of about 60 to about 79 kg/m 3 ; d) a compressive strength of less than about 0.82 kg f /cm 2 and a density of about 80 to about 99 kg/m 3 ; and e) a compressive strength of less than about 0.98 kg f /cm 2 and a density of about 100 to about 119 kg/m 3 .

3 . The method of claim 1 , wherein the haptic value of the foam composition is about 3.2 or less.

4 . The method of claim 1 , wherein the thermoforming ratio of the foam composition is at least about 0.48 at a temperature in the range of about 100 to about 220° C.

5 . The method of claim 1 , wherein the shrinkage value of the foam composition after 1 hour at 120° C. is less than about 5% and the shrinkage value of the foam composition after 10 minutes at 140° C. is less than about 10%.

6 . The method of claim 1 , wherein the polypropylene based polymer is selected from the group consisting of a polypropylene, impact modified polypropylene, polypropylene-ethylene copolymer, metallocene polypropylene, metallocene polypropylene-ethylene copolymer, polypropylene based polyolefin plastomer, polypropylene based polyolefin elasto-plastomer, polypropylene based polyolefin elastomer, polypropylene based thermoplastic polyolefin blend and polypropylene based thermoplastic elastomeric blend.

7 . The method of claim 1 , further comprising extruding the blended composition.

8 . The method of claim 1 , wherein the chemical blowing agent is azodicarbonamide.

9 . The method of claim 1 , wherein the crosslinking monomer is divinylbenzene.

10 . A method of making a foam composition comprising:
a) blending a composition comprising (i) about 15 to about 50 parts by weight of an olefin block copolymer with a controlled block sequence having a melt flow index of about 0.1 to about 15 grams per 10 minutes at 190° C. and a melting temperature of at least about 115° C., (ii) about 50 to about 85 parts by weight of at least one polypropylene based polymer having a melt flow index from about 0.1 to about 25 grams per 10 minutes at 230° C., (iii) a crosslinking monomer and (iv) a chemical blowing agent to produce a blended composition; b) crosslinking the blended composition to obtain a crosslinked composition having a crosslinking degree of about 45 to about 75%; and c) foaming the crosslinked composition at an elevated temperature to obtain a foam composition having a density of about 20 to about 250 kg/m 3 .

11 . The method of claim 10 , wherein the foam composition has a compressive strength and density selected from the group consisting of:
a) a compressive strength of less than about 0.46 kg f /cm 2 and a density of less than about 40 kg/m 3 ; b) a compressive strength of less than about 0.76 kg f /cm 2 and a density of about 40 to about 59 kg/m 3 ; c) a compressive strength of less than about 1.07 kg f /cm 2 and a density of about 60 to about 79 kg/m 3 ; d) a compressive strength of less than about 1.38 kg f /cm 2 and a density of about 80 to about 99 kg/m 3 ; and e) a compressive strength of less than about 1.68 kg f /cm 2 and a density of about 100 to about 119 kg/m 3 .

12 . The method of claim 10 , wherein the haptic value of the foam composition is about 3.2 or less.

13 . The method of claim 10 , wherein the thermoforming ratio of the foam composition is at least about 0.48 at a temperature in the range of about 100 to about 220° C.

14 . The method of claim 10 , wherein the shrinkage value of the foam composition after 1 hour at 120° C. is less than about 5% and the shrinkage value of the foam composition after 10 minutes at 140° C. is less than about 10%.

15 . The method of claim 10 , wherein the shear strength of the foam composition is at least one selected from the group consisting of:
a) greater than about 50 kg f at a temperature in the range of about 60 to about 80° C.; b) greater than about 11 kg f when measured at 140° C.; c) greater than about 9 kg f when measured at 150° C.; d) greater than about 6 kg f when measured at 160° C.; e) greater than about 4 kg f when measured at 170° C.; f) greater than about 2 kg f when measured at 180° C.; and g) about 2 kg f to about 50 kg f at a temperature in the range of about 60 to about 180° C.

16 . The method of claim 10 , wherein the polypropylene based polymer is selected from the group consisting of a polypropylene, impact modified polypropylene, polypropylene-ethylene copolymer, metallocene polypropylene, metallocene polypropylene-ethylene copolymer, polypropylene based polyolefin plastomer, polypropylene based polyolefin elasto-plastomer, polypropylene based polyolefin elastomer, polypropylene based thermoplastic polyolefin blend and polypropylene based thermoplastic elastomeric blend.

17 . The method of claim 10 , further comprising extruding the blended composition.

18 . The method of claim 10 , wherein the chemical blowing agent is azodicarbonamide.

19 . The method of claim 10 , wherein the crosslinking monomer is divinylbenzene.

Assignees

• Toray Plastics America Inc

Inventors

• Sieradzki Pawel
• Baldwin Jesse J
• Lippy Jeffrey S

Classifications

• Y10T428/249976

  Voids specified as closed · CPC title

• C08J2453/00

  Characterised by the use of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives of such polymers · CPC title

• C08J2423/00

  Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers · CPC title

• B32B5/245

  another layer next to it being a foam layer · CPC title

• Y10T442/2139

  Coating or impregnation specified as porous or permeable to a specific substance [e.g., water vapor, air, etc.] · CPC title