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Crystalline polyglycolic acid, polyglycolic acid composition and production process thereof

a technology of polyglycolic acid and polyglycolic acid, which is applied in the field of crystalline polyglycolic acid, polyglycolic acid composition and production process thereof, can solve the problems of plastic waste disposal becoming a great problem, thermal properties not always suitable for melt processing, stretch processing, etc., and achieve excellent melt stability, excellent melt processability, and the effect of preventing the generation of gasses upon their melting

Inactive Publication Date: 2003-07-03
KUREHA KAGAKU KOGYO KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0115] According to the present invention, there are provided polyglycolic acid modified in thermal properties such as crystallinity, and a production process thereof. The polyglycolic acid modified in crystallinity according to the present invention is excellent in melt processability, stretch processability, etc., and is suitable for use as a polymer material for sheets, films, fibers, blow molded products, composite materials (multi-layer films, multi-layer containers, etc.), other molded or formed products, etc. According to the present invention, there are also provided polyglycolic acid compositions which are so excellent in melt stability that generation of gasses upon their melting is prevented, and a production process thereof. According to the present invention, there are further provided polyglycolic acid compositions modified in thermal properties such as crystallinity and improved in melt stability. According to the present invention, there is still further provided a process for controlling the crystallinity of polyglycolic acid.

Problems solved by technology

In recent years, the disposal of plastic waste has become a great problem with the increase of plastic products.
However, the production techniques of the polyglycolic acid is not sufficiently established compared with the general-purpose polymer materials, and so its thermal properties are not always suitable for melt processing, stretch processing, etc.
The polyglycolic acid is insufficient in melt stability, for example, in that it tends to generate gasses upon its melt processing.
However, such a polymer is easy to crystallize upon its cooling from a molten state when it is extruded into a sheet, film, fiber or the like, and so it is difficult to provide any transparent formed product.
A polymer small in this temperature difference generally involves a problem that a stretchable temperature range is narrow upon stretching of a sheet, film, fiber or the like formed from such a polymer, or stretch blow molding of the polymer.
Therefore, the melt processing or stretch processing using a conventional crystalline polyglycolic acid has involved a problem that forming conditions such as forming temperature or stretching temperature are limited to narrow ranges.
As a result, the crystallization of the polyglycolic acid was observed on the sheet, and no transparent amorphous sheet was able to be obtained.
Further, polyglycolic acid is not sufficient in melt stability and has a tendency to easily generate gasses upon its melt processing.
In addition, it has been found that many of additives such as a catalyst deactivator, a nucleating agent, a plasticizer and an antioxidant deteriorate the melt stability of polyglycolic acid.
When the melt stability of polyglycolic acid is insufficient, forming or molding conditions such as forming or molding temperature are limited to narrow ranges, and the quality of the resulting formed or molded product is easy to be deteriorated.

Method used

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  • Crystalline polyglycolic acid, polyglycolic acid composition and production process thereof
  • Crystalline polyglycolic acid, polyglycolic acid composition and production process thereof
  • Crystalline polyglycolic acid, polyglycolic acid composition and production process thereof

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0123] An aluminum pan was charged with 10 mg of polyglycolic acid (melting point Tm=222.degree. C., melt enthalpy of crystal=71 J / G) synthesized by ring-opening polymerization of glycolide, and the polyglycolic acid was heated from 50.degree. C. to a predetermined temperature at a heating rate of 10.degree. C. / min under a nitrogen atmosphere at 10 ml / min (first heating). After the polyglycolic acid was held for 2 minutes at the predetermined temperature, it was cooled to 50.degree. C. at a cooling rate of 10.degree. C. / min (first cooling). The melting point Tm was found from an endothermic peak attributable to the melting of the crystal upon the first heating, and the crystallization temperature Tc.sub.2 was found from an exothermic peak attributable to crystallization upon the first cooling. The measuring results including the crystallization temperatures Tc.sub.2 and the crystallization enthalpies (J / g) found from the area of the crystallization peak when the predetermined temper...

example 2

[0125] The same polyglycolic acid as that used in Example 1 was melted at 270.degree. C., formed into a sheet by a water-cooled press and cooled. As a result, a transparent sheet was obtained. This sheet was able to be stretched.

example 3

[0127] An aluminum pan was charged with 10 mg of polyglycolic acid (melting point Tm=222.degree. C., melt enthalpy of crystal=71 J / g) synthesized by ring-opening polymerization of glicolide, and the polyglycolic acid was heated from -50.degree. C. to a predetermined temperature A at a heating rate of 10.degree. C. / min under a nitrogen atmosphere at 10 ml / min (first heating). After the polyglycolic acid was held for 2 minutes at the predetermined temperature, it was cooled to -50.degree. C. at a cooling rate of 10.degree. C. / min (first cooling). The polyglycolic acid was heated again from -50.degree. C. to a predetermined temperature at a heating rate of 10.degree. C. / min (second heating). After the polyglycolic acid was held for 2 minutes at the predetermined temperature B, it was cooled to -50.degree. C. at a cooling rate of 10.degree. C. / min (second cooling). The predetermined temperatures A and B in the first heating and second heating were changed to 250.degree. C. and 250.degre...

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Abstract

Crystalline polyglycolic acid wherein a difference between the melting point Tm and the crystallization temperature Tc2 is not lower than 35° C., and a difference between the crystallization temperature Tc1 and the glass transition temperature Tg is not lower than 40° C. A production process of polyglycolic acid modified in crystallinity, comprising applying heat history to crystalline polyglycolic acid at a temperature of not lower than (the melting point Tm of the crystalline polyglycolic acid+38° C.). A polyglycolic acid composition comprising crystalline polyglycolic acid and a heat stabilizer, wherein a difference (T2-T1) between the temperature T2 at 3%-weight loss on heating of the polyglycolic acid composition and the temperature T1 at 3%-weight loss on heating of the crystalline polyglycolic acid is not lower than 5° C.

Description

[0001] The present invention relates to polyglycolic acid (including polyglycolide) modified in thermal properties such as crystallinity, and a production process thereof. The polyglycolic acid according to the present invention is excellent in melt processability, stretch processability, etc., and is suitable for use as a polymer material for, for example, sheets, films, fibers, blow molded products, composite materials (multi-layer films, multi-layer containers, etc.) and other molded or formed products. The present invention also relates to a polyglycolic acid composition which is so excellent in melt stability that generation of gasses attributable to low-molecular weight products produced upon melting is prevented, and a production process thereof. The present invention further relates to a process for controlling the crystallinity of polyglycolic acid.[0002] Polyglycolic acid is known to be degraded by microorganisms or enzymes present in the natural world such as soil and sea...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B29C49/00B65D1/02C07C59/10C08G63/08C08G63/80C08G63/88C08K5/49C08K5/527
CPCC08G63/08C08G63/80C08G63/88C08K5/527C08L67/04C08G63/06
Inventor YAMANE, KAZUYUKIMIURA, HIROMITSUONO, TOSHIHIKONAKAJIMA, JUNJIITOH, DAISUKE
Owner KUREHA KAGAKU KOGYO KK
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