Polypropylene resin composition and expanded molding

Patent metadata

Field	Value
Publication number	US-9522984-B2
Application number	US-201214344553-A
Country	US
Kind code	B2
Filing date	Oct 17, 2012
Priority date	Oct 17, 2011
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

A polypropylene-based resin composition is provided that can provide a foam molding that exhibits an excellent closed cell characteristic and excellent extrusion characteristics, that is light weight and has a rigid feel, and that has an excellent recyclability.
This polypropylene-based resin composition contains 100 weight % or is less than 100 weight % but at least 70 weight % of component (A) below and contains 0 weight % or is greater than 0 weight % but not more than 30 weight % of component (B) below,
component (A):
a propylene-based resin composition that comprises at least the following two components: a propylene-α-olefin copolymer (A1) satisfying conditions (A-1) to (A-3) and a propylene homopolymer (A2), (A1) and (A2) being obtained by polymerization by a multistage polymerization method, and this propylene-based resin composition having a content of (A1) of 1 to 20 weight % and a content of (A2) of 99 to 80 weight %, having a melt flow rate in the range from 5 to 20 g/10 minutes and exhibiting strain hardening in a measurement of extensional viscosity at a temperature of 180° C. and a strain rate of 10 s −1 ,
(A-1) an α-olefin content of 15 to 85 weight %, (A-2) an intrinsic viscosity η of 5 to 20 dL/g, (A-3) a Mw/Mn of 5 to 15;
component (B):
a propylene-based resin composition comprising at least the following two components: a propylene homopolymer or a propylene-α-olefin copolymer having a content of non-propylene α-olefin of less than 1 weight % (B1), which has an MFR of 10 to 1000 g/10 minutes, and a propylene-α-olefin copolymer (B2) that has a weight-average molecular weight of 500,000 to 10,000,000 and a content of non-propylene α-olefin of 1 to 15 weight %, (B1) and (B2) being obtained by polymerization by a multistage polymerization method, and this propylene-based resin composition having a content of (B1) of 50 to 90 weight % and a content of (B2) of 50 to 10 weight %, and satisfying prescribed conditions (B-1) to (B-3).

First claim

The invention claimed is:

1. A polypropylene-based resin composition, comprising component (A) and component (B), wherein, based on 100 weight % sum of components (A) and (B), a component (A) content is less than 100 weight % but at least 70 weight % and a component (B) content is greater than 0 weight % but not more than 30 weight %,
wherein
component (A) is a propylene-based resin composition that comprises a propylene-α-olefin copolymer (component (A1)) and a propylene homopolymer (component (A2)),
components (A1) and (A2) are obtained by polymerization by a multistage polymerization method,
the propylene-based resin composition has a component (A1) content of 1 to 20 weight % and a component (A2) content of 99 to 80 weight %, based on a sum of components (A1) and (A2) of 100 weight %, and has a melt flow rate in the range from 5 to 20 g/10 minutes and exhibits strain hardening in a measurement of extensional viscosity at a temperature of 180° C. and a strain rate of 10 s −1 ,
the propylene-α-olefin copolymer (A1) satisfies conditions (A-1) to (A-3):
(A-1) an α-olefin content of 15 to 85 weight %, where a total amount of monomer constituting component (A1) is 100 weight %;
(A-2) an intrinsic viscosity η of 5 to 20 dL/g; and
(A-3) a Mw/Mn of 5 to 15,
component (B) is a propylene-based resin composition comprising a propylene homopolymer or a propylene-α-olefin copolymer having a content of non-propylene α-olefin of less than 1 weight % (component (B1)), which has an MFR of 10 to 1000 g/10 minutes, and a propylene-α-olefin copolymer (component (B2) that has a weight-average molecular weight of 500,000 to 10,000,000 and a content of non-propylene α-olefin of 1 to 15 weight %,
components (B1) and (B2) are obtained by polymerization by a multistage polymerization method, and
the propylene-based resin composition has a component (B1) content of 50 to 90 weight % and a component (B2) content of 50 to 10 weight %, where a sum of components (B1) and (B2) is 100 weight %, and satisfies conditions (B-1) to (B-3):
(B-1) an MFR of 0.1 to 20 g/10 minutes;
(B-2) a relationship between a melt tension (MT) and the MFR satisfying the following formula
log MT>−0.97×log MFR+1.23; and

(B-3) a longest relaxation time (τd) of at least 100 seconds.

2. The composition according to claim 1 , wherein the component (A) content is from 70 to 97 weight % and the component (B) content is from 3 to 30 weight %.

3. The composition according to claim 1 , wherein component (A) has a strain hardening exponent λmax (10) of at least 1.2 in the measurement of extensional viscosity at a temperature of 180° C. and a strain rate of 10 s −1 .

4. The composition according to claim 1 , wherein the α-olefin of the propylene-α-olefin copolymer (A1) is selected from the group consisting of ethylene, butene, pentene, hexene, heptene, nonene, decene, 1-methylbutene, and 1-methylpentene.

5. The composition according to claim 1 , wherein the intrinsic viscosity η of the propylene-α-olefin copolymer (A1) is from 6.5 to 17 dL/g.

6. The composition according to claim 1 , wherein the intrinsic viscosity η of the propylene-α-olefin copolymer (A1) is from 8 to 15 dL/g.

7. The composition according to claim 1 , wherein the Mw/Mn of the propylene-α-olefin copolymer (A1) is from 10 to 15.

8. The composition according to claim 1 , wherein the propylene homopolymer (A2) has a stereoregularity of at least 96%.

9. A polypropylene-based resin foam molding, wherein the molding is molded by a process comprising: adding a foaming agent to the polypropylene-based resin composition according to claim 1 ;
and carrying out extrusion foam molding thereof.

10. The molding according to claim 9 , wherein the molding is a foam sheet molded by extrusion from a slit die or circular die.

11. A polypropylene-based resin foam thermoformed article formed by a process comprising thermoforming the foam sheet according to claim 10 .

12. A polypropylene-based resin foam hollow molding, wherein the molding is a hollow molding molded by a process comprising:
adding a foaming agent to the polypropylene-based resin composition according to claim 1 ;
extruding the composition to obtain a parison; and
subsequently performing blow molding within a mold.

Assignees

• Japan Polypropylene Corp

Inventors

• KANENO Motoki
• Yamashita Koji
• Tsuji Hiroshi
• Suzuki Akihiro
• Kitade Shinichi
• Aoki Masaru
• TERAYAMA Isamu

Classifications

• B29C51/02

  Combined thermoforming and manufacture of the preform · CPC title

• B29C2948/922

  Viscosity; Melt flow index [MFI]; Molecular weight · CPC title

• B29C48/0012

  combined with shaping by internal pressure generated in the material, e.g. foaming · CPC title

• B29C48/92

  Measuring, controlling or regulating · CPC title

• B29K2023/14

  Copolymers of polypropylene (B29K2023/16 takes precedence) · CPC title