Method for producing a polylactic acid-based film or sheet

Patent metadata

Field	Value
Publication number	US-10253145-B2
Application number	US-201514875736-A
Country	US
Kind code	B2
Filing date	Oct 6, 2015
Priority date	Oct 2, 2008
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

A method of producing a polylactic acid based film or sheet with improved heat resistance and comprised of a resin composition containing a polylactic acid according to a melt film forming method, wherein the resin composition comprises polylactic acid (A), an acidic functional group-denatured olefin based polymer (B) containing an acidic functional group, and having an acid number of 10-70 mg KOH/g and a weight average molecular weight of 10,000-80,000, and a tetrafluoroethylene based polymer (C), which method comprises performing melt film formation at a temperature of the resin composition between the crystallization temperature (Tc) in a decreasing temperature process of the resin composition +15° C. and the melting temperature (Tm) in a raising temperature process −5° C., or solidifying the resin composition melt-formed in a film state by cooling after a temperature controllable step at crystallization temperature (Tc) in the decreasing temperature process ±10° C.

First claim

The invention claimed is:

1. A method of producing a film or sheet of a resin composition containing a polylactic acid according to a melt film forming method, wherein the resin composition comprises polylactic acid (A), an acidic functional group-denatured olefin based polymer (B) containing an acidic functional group, and having an acid number of 10-70 mg KOH/g and a weight average molecular weight of 10,000-80,000, and a tetrafluoroethylene based polymer (C),
which method comprises forming the film or sheet from the resin composition by a melt film formation,
wherein, during the melt film formation, the resin composition has a temperature between a temperature 15° C. higher than a crystallization temperature (Tc) of the resin composition in a decreasing temperature process and a temperature 5° C. lower than a melting temperature (Tm) of the resin composition in a raising temperature process, or
the melt film formed resin composition is solidified by cooling the melt film formed resin composition after a crystallization promoting step at a temperature which is between 10° C. below and 10° C. above the crystallization temperature (Tc) of the resin composition in the decreasing temperature process.

2. The production method according to claim 1 , wherein, during the melt film formation, the resin composition has the temperature between the temperature 15° C. higher than the crystallization temperature (Tc) of the resin composition in the decreasing temperature process and the temperature 5° C. lower than the melting temperature (Tm) of the resin composition in the raising temperature process, and the melt film formed resin composition is solidified by cooling the melt film formed resin composition after the crystallization promoting step at the temperature which is between 10° C. below and 10° C. above the crystallization temperature (Tc) of the resin composition in the decreasing temperature process.

3. The production method according to claim 1 , wherein the resin composition comprises the acidic functional group-denatured olefin based polymer (B) in an amount of 0.1-5.0 parts by weight per 100 parts by weight of the polylactic acid (A).

4. The production method according to claim 1 , wherein the resin composition comprises the tetrafluoroethylene based polymer (C) in an amount of 0.1-10.0 parts by weight per 100 parts by weight of the polylactic acid (A).

5. The production method according to claim 1 , wherein the melt film forming method is a technique comprising finally passing the resin composition in a molten state through a gap between two metal rolls to achieve a desired film thickness.

6. The production method according to claim 5 , wherein the melt film forming method is a calender film forming method.

7. The production method according to claim 1 , wherein the acidic functional group in the acidic functional group-denatured olefin based polymer is an acid anhydride.

8. The production method according to claim 1 , wherein the resin composition further comprises 0.1-5.0 parts by weight of crystallizing agent (D) per 100 parts by weight of the polylactic acid (A).

9. The production method according to claim 1 , wherein the crystallization promoting step of the resin composition is achieved by a metal roll.

10. A method of producing a film or sheet of a resin composition containing a polylactic acid according to a calender film forming method, wherein the resin composition comprises 100 parts by weight of polylactic acid (A), 0.1-5.0 parts by weight of an acidic functional group-denatured olefin based polymer (B) containing an acidic functional group, and having an acid number of 10-70 mg KOH/g and a weight average molecular weight of 10,000-80,000, and 0.1-10.0 parts by weight of a tetrafluoroethylene based polymer (C),
which method comprises forming the film or sheet from the resin composition by calender-rolling,
wherein, during the calender-rolling, the resin composition has a temperature between a temperature 15° C. higher than a crystallization temperature (Tc) of the resin composition in a decreasing temperature process and a temperature 5° C. lower than a melting temperature (Tm) of the resin composition in a raising temperature process, or
the melt film formed resin composition is solidified by cooling the melt film formed resin composition after a crystallization promoting step at a temperature which is between 10° C. below and 10° C. above the crystallization temperature (Tc) of the resin composition in the decreasing temperature process.

11. The production method according to claim 10 , wherein, during the calender-rolling the resin composition has the temperature between the temperature 15° C. higher than the crystallization temperature (Tc) of the resin composition in the decreasing temperature process and the temperature 5° C. lower than the melting temperature (Tm) of the resin composition in the raising temperature process, and the melt film formed resin composition is solidified by cooling the melt film formed resin composition after the crystallization promoting step at the temperature which is between 10° C. below and 10° C. above the crystallization temperature (Tc) of the resin composition in the decreasing temperature process.

12. The production method according to claim 10 , wherein the acidic functional group in the acidic functional group-denatured olefin based polymer is an acid anhydride.

13. The production method according to claim 10 , wherein the resin composition further comprises 0.1-5.0 parts by weight of crystallizing agent (D) per 100 parts by weight of the polylactic acid (A).

14. The production method according to claim 10 , wherein the crystallization promoting step of the resin composition is achieved by a metal roll.

Assignees

• Nitto Denko Corp

Inventors

• Ishiguro Shigeki
• Senda Hiroki

Classifications

• C08L51/06

  grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond · CPC title

• B29C47/8845

  Operations & Transport · mapped topic

• C08L23/02

  not modified by chemical after-treatment · CPC title

• C09D4/06

  {Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond} in combination with a macromolecular compound other than an unsaturated polymer of groups C09D159/00 - C09D187/00 · CPC title

• B29C43/24

  Calendering · CPC title