JP2011122126A - Modification of polylactic acid resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide (1) a polylactic acid resin composition economically producible with a general molding machine and a range of molding conditions of general resins and (2) a polylactic acid resin composition suitable for a wide range of applications from hard to semihard or soft products by imparting flexibility to a polylactic acid resin and without much affecting the biodegradability. <P>SOLUTION: The polylactic acid resin composition having improved processability and flexibility comprises 100 pts.wt. of a polylactic acid resin, and 3-80 pts.wt. of a conductive or antistatic plasticizer whose volume resistivity and/or surface resistivity is 10<SP>10</SP>Ω-cm or less when added in 50 pts.wt. to 100 pts.wt. of a vinyl chloride resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

Detailed Description of the Invention

The present invention relates to a modification for the purpose of improving the moldability of polylactic acid resin and expanding its application.

In recent years, environmental pollution problems caused by resins, such as marine pollution and soil pollution, have been highlighted. As countermeasures, biodegradable resins and naturally disintegrating resins have been proposed and evaluated on the market. However, the current situation is that the spread of the product has been delayed due to problems in quality and moldability and poor usability.
The problems in quality and performance are as follows: (1) The molding processing width is narrow, and economical production is difficult with a general-purpose molding machine.
(2) There is no flexibility in terms of quality, and it is hard and brittle, so it is limited in use.
(3) Modification by adding a large amount of other resin or the like impairs biodegradability.
Such problems have been pointed out.

Problems to be solved by the present invention

The present invention gives flexibility to the polylactic acid resin without significantly affecting biodegradability,
(1) To provide a biodegradable resin composition that can be produced economically within a range of molding conditions for a general-purpose resin using a general-purpose molding machine.
(2) To provide a biodegradable resin composition suitable for a wide range of applications from hard to semi-rigid and soft products.

Means to solve the problem

The present inventor has found that a resin composition comprising an acrylic styrene copolymer containing 30% or more of an alkyl acrylate having 4 or more carbon atoms and a plasticizer for a resin already solves the above problems with respect to the biodegradable resin. A patent application was filed (Japanese Patent Application No. 2009-253455). However, in the present invention, the solid product resistance value and / or the surface specific resistance value is 10 ¹⁰ Ω or less when blended with 50 parts by weight of 100 parts by weight of polylactic acid and 100 parts by weight of polyvinyl chloride resin. The present invention was completed by finding that the above-mentioned problems can be achieved even with a composition comprising 3 to 80 parts by weight of a plasticizer.

The invention's effect

For example, in the case of polylactic acid, the melting point is usually 170 ° C. or higher, and a molded product cannot be produced unless the molding process conditions are 180 ° C. or higher. However, the present resin composition can be molded at 150 ° C. Therefore, it can be sufficiently molded by general-purpose steam heating and oil heating molding machines. Moreover, since this composition can adjust a softness | flexibility according to the quantity of a plasticizer, it can expand | deploy to a hard product, a semi-rigid product, and a soft product according to a use.

As the polylactic acid resin used in the present invention, various optical isomer polylactic acid, copolymers of lactic acid and glycolide, ε-caprolactone, ethylene oxalate and the like are used in addition to commercially available polylactic acid.

As the conductive or antistatic plasticizer used here, when the volume resistivity value and / or the surface resistivity value is 10 ¹⁰ (Ω · cm) or less, the affinity for the polylactic acid resin is extremely large, and the plasticizing effect Is remarkable. As such conductive or antistatic plasticizers, adipic acid-based, polyester-based, and phthalic acid-based ones are commercially available, and any of them exhibiting the above resistance value is effective. However, the lower the resistance value, the greater the effect.

  The resin composition of the present invention is mixed using an ordinary mixing apparatus such as a Henschel mixer (trade name), a super mixer, a ribbon blender, etc., and directly or granulated, and then an injection molding method, an extrusion molding method, a blow molding method. It is used for the production of the desired molded product by a calendar molding method or the like.

[Comparative Examples 1 and 2]
3 parts by weight of DOP and appropriate amounts of antioxidants and lubricants are weighed and mixed with 100 parts by weight of polylactic acid (Lacia H100J, Mitsui Chemicals), and kneaded with an 8-inch roll set at a temperature of 160 to 180 ° C. A 5 mm thick sheet was prepared. The sheet was measured for hardness with a JISA hardness meter, and with a shopper type tensile tester for tensile strength and elongation. The results are shown in Table 1. As can be seen, the processing temperature is 180 ° C., the resin temperature is 175 ° C., and the hardness (JISA) is 95 ° C. or more, which is equivalent to hard when it is a vinyl chloride resin.

[Comparative Examples 3 to 5]
150 parts by weight of polylactic acid (Mitsui Chemicals Lacia H100J) 10 to 40 parts by weight of plasticizer for resin (DOP), 10 parts by weight of epoxidized soybean oil and appropriate amounts of antioxidants and lubricants are weighed and mixed. A sheet having a thickness of about 0.5 mm was prepared by kneading with an 8-inch roll whose temperature was set to ˜180 ° C. The sheet was measured for hardness with a JISA hardness meter, and with a shopper type tensile tester for tensile strength and elongation. The results are shown in Table 1. As can be seen, the processing temperature and the resin temperature decreased by 5 to 10 ° C., but the hardness (JISA) was 95 degrees or more, and the flexibility and the tensile physical properties were not improved.

[Examples 1 to 3]
Conductive plasticizer (manufactured by Adeka, LV808, volume specific resistance value 8.2 × 10 ⁸ , LV838, volume specific resistance value 9.0 × 10 ^{9 with} respect to 100 parts by weight of polylactic acid used in Comparative Examples 1 and 2 40) 80 parts by weight and appropriate amounts of antioxidants and lubricants were weighed and mixed, and film formation was carried out in the same manner as in the comparative example with an 8-inch roll set at a temperature of 150-170 ° C. This sheet was measured in the same manner as in the comparative example. The results are shown in Table 1. As can be seen, the processing temperature and the resin temperature were reduced by 10 to 20 ° C., and the hardness (JISA) was also reduced to 80 to 85 degrees, corresponding to a soft equivalent when using a vinyl chloride resin.

[Comparative Example 3]
100 to 100 parts by weight of polylactic acid used in Comparative Examples 1 and 2, 100 parts by weight of the conductive plasticizer used in Examples 4 and 5 and appropriate amounts of antioxidant and lubricant were weighed and mixed to 150 to 160 ° C. The film was formed in the same manner as in Comparative Examples 1 and 2 with an 8-inch roll set at a temperature of 5 mm. However, the melt on the roll was too soft as it was, and could not be drawn out to the sheet. Therefore, the film was formed by reducing the roll temperature to 140 ° C. Then, the same physical properties were measured, but if the sample was allowed to stand at room temperature for 2 to 3 days after the measurement, the plasticizer was blown out on the surface. The results are shown in Table 1.

Claims (1)

Conductive or antistatic properties having a volume resistivity and / or surface resistivity of 10 ¹⁰ (Ω · cm) or less when added to 100 parts by weight of polylactic acid resin and 100 parts by weight of vinyl chloride resin A polylactic acid resin composition comprising 3 to 80 parts by weight of a plasticizer.