JPH08244836A - Biodegradable polylactic acid compound material - Google Patents

Abstract

PURPOSE: To obtain a packaging material which has excellent wrapping capability and cost balance and eliminates waste-disposal problems, by compounding polylactic acid, whose L-form/D-form (mole ratio) is specified in L-D copolymer ratio, and a pulp material by means of impregnation, etc. CONSTITUTION: A biodegradable material suitable as a packaging material, especially a sheet-like material comprising paper as its base material, is obtained by compounding polylactic acid and a pulp material by means of impregnation, coating, lamination, etc. The examples of the pulp materials are paper, a nonwoven-fabric-like material, a compression molded material of pulp, etc., and the paper is particularly preferable in practical use. As the polylactic acid, an L-D copolymer is preferable, and one having an L/D (mole ratio) of 60/4-98/2 is suitable. A polymer whose L/D ratio is 60/40 or below is too soft, lacks strength, and is therefore unsuitable as the wrapping material. In the case of a polymer whose L-form/D-form ratio is 98/2 or above, on the other hand, the degree of crystallization increases, causing a decrease in biodegradability, therefore it is not preferable, either.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biodegradable composite material suitable as a packaging material of pulp material and polylactic acid, and provides an environment-friendly biodegradable packaging material processed into a bag shape, a container shape or the like. To do.

2. Description of the Related Art Today, light and durable plastic films and sheets are processed and used in large quantities as packaging materials according to the purpose of packaging. In particular, plastics such as polyethylene, polypropylene and polystyrene have become the mainstream of packaging materials now, taking advantage of their features such as low cost, moldability and transparency.

However, today, a large amount of packaging materials are often discarded as they are after use. They are non-decomposable, damage to the incinerator during incineration, generation of harmful gas, etc. For that reason, plastic waste disposal has become a social problem. Although recycling of plastics has been proposed as a countermeasure, it has not been effective due to quality problems such as contamination of impurities and heat deterioration during collection, and the cost of collection being high. As a packaging material,
As an alternative material, eco-friendly, lightweight, inexpensive paper can be considered, but paper has problems of tear strength and strength deterioration when wet with water, and it is difficult to waterproof and barrier properties, so its application is quite limited. Has been done. As a packaging material that has improved the drawbacks of paper, there is one in which paper is laminated with a polyethylene film or the like, but it is not sufficient as a substitute material for plastic containers due to the cost of recovery work and the above-mentioned problems during incineration. Biodegradable polymers are considered as eco-friendly packaging materials, but at present, there is no excellent balance between moldability and biodegradability, and no material that can be impregnated or coated with a general solvent has been found. . The present invention provides an environment-friendly packaging material which has an excellent packaging function and cost balance, and which greatly solves the problem of waste disposal of the packaging material.

[0002]

That is, the present invention relates to a biodegradable material suitable for a packaging material, which is characterized in that a pulp material is compounded with polylactic acid by impregnation, coating, laminating and the like, particularly paper-based material. It is the provision of sheet-like materials. Examples of the pulp material of the present invention include paper, non-woven materials, pulp compression molded products, and the like, and paper is particularly preferable in terms of practical use. Further, the polylactic acid of the present invention is preferably a copolymer of L-form and D-form, and the L-form / D-form (molar ratio) is from 60/40.
A polylactic acid of 98/2 is suitable. When the L-form / D-form ratio is 60/40 or less, the polymer becomes too soft and the strength is insufficient, which is not suitable as a packaging material. Also, the L / D ratio is 9
When it is 8/2 or more, the degree of crystallinity increases and the biodegradability decreases, which is not preferable. L-form / D-form (molar ratio) is 60/40 to 98 /
Polylactic acid of No. 2 not only has an excellent balance of strength and biodegradability, but also dissolves in general solvents, so that it can be easily impregnated or coated on paper as a solvent solution. It is also possible to form a film by extrusion molding or the like and laminate it with paper, or heat-melt and directly coat the paper. The composite sheet of paper and polylactic acid obtained in this way has strength and water resistance suitable for packaging materials, and is biodegradable even if it is buried in the soil as it is or discarded in rivers or seawater. It decomposes into lactic acid or carbon dioxide gas and water, and can be safely returned to the natural world.
Since the composite sheet of the present invention is heat-soluble, it can be thermoformed and can be formed into a container such as a tray. Moreover, since the composite sheets of the present invention can be overlapped and partially heat-sealed, they can be processed into a box shape or a bag shape. The composite sheet of the present invention that can be processed in this manner is used in place of conventional plastic packaging materials, such as food containers such as trays, lunch boxes, cups and plates, tetra packs such as milk and juice, and box packs. It can be used as a container for beverages, a garbage bag containing food waste, general waste, etc., a moisture-proof sheet / bag for industrial use, etc. In addition, a composite material of a non-woven sheet having coarse mesh and polylactic acid can be used as a material such as a drain bag and a tea bag. Furthermore, a pulp mold material can be obtained by combining pulp fibers and polylactic acid and compression-molding them, and can be effectively used as a substitute material for expanded polystyrene for packaging, which is a problem in waste disposal.

[0003]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to these examples. Example 1 A paper cup having a basis weight of 310 g / m ² was prepared as a paper cup, and the surface thereof had a polylactic acid (EcoPLA: Cargill) toluene content of 90% by weight of L-form / D-form (molar ratio) of 90/10.
Was applied. After drying at 50 ° C. for 1 hour, a glossy waterproof cup was obtained. The basis weight of the dried cup is 400 g / m ²
Met. Drinking water was placed in this cup and allowed to stand for one week, but no exudation of drinking water or deformation of the container was observed. When this cup was composted, the original shape could not be maintained in a month. Comparative Example 1 Using a paper cup laminated with a polyethylene film having a thickness of 50 μm, a drinking water leaving test was carried out in the same manner as in Example 1. No bleeding of the drinking water or deformation of the container was observed. Was not composted after one month. Example 2 A paper tray having a basis weight of 450 g / m ² produced by pulp molding was impregnated with the 20% toluene solution of polylactic acid used in Example 1. After drying at 50 ° C. for 1 hour, a tray having smoothness, water resistance and oil resistance was obtained. The basis weight of the dried tray was 550 g / m ² . The edible oil was put into this tray and left for one week, but no bleeding of the edible oil or deformation of the tray was observed. When this tray was composted, the original shape could not be retained within a month. Example 3 The polylactic acid used in Example 1 was hot melted and extruded to obtain a film having a thickness of 0.2 mm. Weigh this film 4
After laminating on 65 g / m ² of paperboard, vacuum forming was performed to prepare a plate having smoothness, water resistance and oil resistance. Vinegar was placed in this dish and left for one week, but no bleeding of the vinegar or deformation of the dish was observed. When this plate was composted, the original shape could not be retained within two months. Example 4 A paper having a basis weight of 157 g / m ² was impregnated with polylactic acid in the same manner as in Example 2, dried and hardened.
A sheet of g / m ² was obtained. This sheet was cut into A4 size, two sheets were stacked, and three sides were heat-sealed at 170 ° C. to form a bag. Although 500 cc of drinking water was placed in this bag and left for one week, no exudation of water or peeling or breakage of the sheet was observed. When this bag was composted, the original shape could not be retained within a month. Comparative Example 2 A bag was made of a polyethylene film having a thickness of 50 μm in the same manner as in Example 4. When 500 cc of water was put into this bag and the same standing test was performed, no exudation of drinking water or peeling or breakage of the sheet was observed, but the bag was not composted even after one month.

[0004]

As is apparent from the above examples, the biodegradable polylactic acid composite of the present invention exhibits practical water resistance and oil resistance similar to those of conventional plastics, and is relatively short after disposal. It can be seen that it exhibits good degradability. Therefore, the biodegradable polylactic acid complex of the present invention is useful as a packaging material for a plastic alternative in which disposal after use is a problem, and is used as a shopping bag, tray, lunch box, plate, cup,
It can be usefully used as a material for beverage containers, tea bags, garbage bags, drainage bags and the like.

Claims (1)

[Claims] 1. A pulp material is a copolymer of L-form and D-form, and polylactic acid having an L-form / D-form (molar ratio) of 60/40 to 98/2 is impregnated, coated, laminated or the like. A biodegradable material suitable as a packaging material, characterized by being compounded by.