KR100212964B1 - Degradable resin composition - Google Patents

Abstract

The present invention relates to a decomposable resin composition, and more particularly, a decomposable resin that can be formed into a disposable diaper, a paper, a cardboard coating, an injection molding, a foaming tray, and a packaging material by forming a high starch and a high molecular weight polylactic acid with amylose content. It relates to a composition.

Description

Degradable Resin Composition

The present invention relates to a degradable resin composition, and more particularly, it is made of a starch having a high amylose content and a polylactic acid having a high molecular weight, so that it can be molded into disposable diapers, paper, cardboard coatings, injection moldings, foam trays and packaging materials. It relates to a resin composition.

In general, the decomposition of the polymer is considered to be a very unfavorable fixation, and until now, research has been conducted on plastics in the direction of improving and stabilizing the decomposition resistance. However, with the quantitative increase of plastic products and problems related to the disposal of plastic wastes with environmental pollution, interest in degradable polymers is increasing.

As a conventionally known technique, US Patent No. 4,021,388 and European Patent No. 409,789 disclose a method for producing biodegradable plastics by containing starch in plastics such as polyethylene, polypropylene, or polystyrene. However, such biodegradable plastics have the disadvantage that only starch is biodegraded in the blended resin mixture and other plastics remain in nature without degrading, causing secondary environmental pollution.

In addition, U.S. Patent Nos. 3,860,538 and 4,337,181 disclose a method of producing photodegradable plastics by introducing a carbonyl device as a photosensitizer or by adding an additive to impart photodegradability to the base polymer. These photodegradable plastics must be exposed to light in order to be decomposed, and if they are buried deep in the ground or in the sea, the photodegraders are less likely to occur, and also cause new problems due to the potential toxicity of additives used to impart photodegradability. There is.

And US Pat. Nos. 3,442,871, 2,703,316 and 4,300,565 disclose methods for manufacturing synthetic degradable polymers. These manufacturing methods are a technique for polyglycolide, polylactide, polydioxaneone and copolymers thereof, and are used in high value-added products such as medical materials because raw materials are expensive.

The present inventors have endeavored to solve the problems of the prior art, and as a result, the present invention has been completed by combining starch, which is a low-cost biodegradable natural polymer material, and polylactic acid capable of mass production in an appropriate content ratio.

Accordingly, an object of the present invention is to provide a resin composition having excellent biodegradability because of starch and polylactic acid.

The present invention is a biodegradable resin composition, starch 5 55 weight With polylactic acid 45 95 weight It is characterized by consisting of.

Starch used in the present invention is a natural polymer material extracted from grains such as potatoes, rice, corn, rye, oats, etc., mainly composed of amylose having a linear structure and amylopectin having a branched structure. In particular, it is preferable to use starch extracted from corn or potatoes because the amylose content, which is a linear structure, is high and can be easily biodegraded.

The polylactic acid used in the present invention is obtained by directly polymerizing lactic acid or by ring-opening polymerization of lactide, and having a number average molecular weight of 10,000 or more, more preferably 50,000 Use 300,000. If the number average molecular weight of the polylactic acid used is less than 10,000, there is a problem that the molding process is difficult and the thermal decomposition is severe.

Degradable resin composition according to the present invention is starch 5 55 weight With polylactic acid 45 95 weight And more preferably starch 15 35 weight With polylactic acid 65 85 weight It contains a case. 5 weights of starch contained in the decomposable resin composition If less than biodegradation is difficult, 55 weight If it exceeds, there is a problem that the mechanical properties deteriorate too quickly. And, the content of polylactic acid is 45 weight If less than 95% of the physical properties required for the final product is poor If it contains in excess, the degradable effect aimed at in this invention cannot be obtained.

In addition, the starch in the present invention has an amylose content of 40 weight More than 40, preferably 40 80 weight Can be used, the amylose content is 40 weight If less is less mold growth, biodegradability is poor, extrusion is difficult, there is a problem that the human friendliness is also poor.

The starch and the polylactic acid resin were mixed with the above-described procedure and extruded in a twin or screw injector to prepare a biodegradable resin having excellent physical properties such as strength and elongation. In order to improve physical performance, a plasticizer, a heat stabilizer, a usability agent, a mold release agent, a lubricant, a colorant, a nucleating agent, and a modifier commonly used in the art may be used to make a shape and shape useful in molding. .

Hereinafter, the present invention will be described in detail with reference to the following Examples, but the present invention is not limited by the Examples.

Example 1

Amylose content 55 500 g of phosphorus corn starch was dispersed in 4 l of distilled water and placed under nitrogen stream. After stirring at a temperature of gelatinization, the mixture was mixed using a roll mill and the water content was 20. Adjusted to. 25 weight of corn starch prepared above And 75 weight polylactic acid having a number average molecular weight of 180,000 Mix and 150 200 The decomposable resin was prepared by kneading extrusion into a twin screw extruder maintaining the temperature of.

Example 2

Amylose content is 40 Phosphorus Corn Starch 40 And 75 weight polylactic acid having a number average molecular weight of 180,000 Degradable resin was prepared in the same manner as in Example 1, except that the mixture was used.

Comparative Example 1

1 weight of corn starch And 99 weight of polylactic acid with the number average molecular weight 180,000 Except for using a decomposable resin was prepared in the same manner as in Example 1.

Comparative Example 2

Corn Starch 80 And polylactic acid 20 having a number average molecular weight of 180,000 Except for using a decomposable resin was prepared in the same manner as in Example 1.

Comparative Example 3

A degradable resin was prepared in the same manner as in Example 1, except that polylactic acid having a number average molecular weight of 9,500 was used.

[Comparative Example 4]

Amylose content 25 Phosphorus corn starch was used to prepare a degradable resin under the same conditions as in Example 1.

Experimental Example

Example 1 2 and Comparative Example 1 The resin prepared in 3 was made of 60μm film, and the physical properties such as tensile strength and elongation were measured according to ASTM D-638, and biodegradability was determined by measuring mold propagation according to ASTM G 21-70. . The results are shown in Table 1 below.

According to the results of Table 1, Example 1 and Example 2 according to the present invention has excellent physical properties including tensile strength and tensile elongation, but also has high mold propagation properties and has easy biodegradation characteristics.

On the other hand, Comparative Example 1, which contains little starch, had good physical properties, but had low mold propagation. In the case of Comparative Example 2, as an example containing a large amount of starch, it was not suitable to meet all the required properties of the final product. In addition, in the case of Comparative Example 3 using polylactic acid having a low number average molecular weight, the physical properties were poor, which was unsuitable for satisfying all the required physical properties of the final product.

Degradable resin composition according to the present invention because of its excellent physical properties and excellent biodegradability, its use is wide, including disposable diapers, paper, cardboard coatings, injection molding, foam trays and packaging materials.

Claims (1)

In the hydrolyzable resin composition comprising polyester and starch having a molecular weight of 1,000 or more, the amylose content is 40 80 weight Phosphorus Starch 5 55 weight And polylactic acid having a number average molecular weight of 10,000 or more 45 95 weight Degradable resin composition, characterized in that consisting of.