JP2966945B2 - Gas barrier easily collapsible resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily collapsible resin composition having gas barrier properties.

[0002]

2. Description of the Related Art In general, synthetic polymers are widely used in various fields because they have high material properties, are excellent in processability, and are inexpensive. However, the molded product is bulky,
Due to its own durability, it does not collapse naturally even when it is dumped or landfilled, and its heat generation is high when incinerated. Therefore, studies have been made to reduce the bulk of the plastic waste by partially decomposing it by light or microorganisms, and to effectively use waste treatment facilities or landfills.

[0003] Above all, a study has been made on a resin composition having a thermoplastic property and an easily biodegradable property by blending a synthetic polymer having thermoplasticity with a completely biodegradable polymer derived from a natural product. Is a popular activity.

[0004] By the way, thermoplastics having gas barrier properties are characterized in that they block oxygen and aroma components, and are used in large quantities in the field of food packaging materials and the like that require oxidation resistance and fragrance retention of the contents. However, food packaging materials account for a very large proportion of the above-mentioned plastic waste, so that it is desired to provide easy disintegration to this field.

[0005] However, there is still no thermoplastic having sufficient gas barrier properties as a food packaging material and easy disintegration by living organisms. At present, there is a problem in the preservability of the food, which is the content, because there is no food.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an easily disintegrable resin composition having good thermoplasticity, easy disintegration by microorganisms in soil, and gas barrier properties.

[0007]

SUMMARY OF THE INVENTION Pullulan is a polysaccharide produced by microorganisms and has the useful characteristics of having complete biodegradability and good gas barrier properties. However, since it does not have thermoplasticity itself, it cannot be melt-molded. In the case of molding as a food packaging material, it is called film casting by casting and drying an aqueous solution of pullulan or coating the solution. At present, it is not widely used because it is only a limited molding method.

[0008] The present inventors have made various investigations on such a problem by blending various synthetic resins having thermoplasticity with pullulan. When blended with polyolefins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer, the blended thermoplastic resin does not have compatibility with pullulan, so a resin composition with extremely low transparency and mechanical strength I could only get it. On the other hand, polyamides such as nylon 6 and nylon 12,
Blends of polyethers such as polyethylene glycol and polyesters such as polyethylene terephthalate show relatively good compatibility and have the effect of imparting thermoplasticity, but have the inherent gas barrier properties of pullulan. However, no barrier plastic was found that could be used for food packaging materials and the like. Next, blending of thermoplastic resins having various gas barrier properties was attempted. When polyvinylidene chloride and polyacrylonitrile were blended, as in the case of the polyolefins, there was no compatibility with pullulan, so that only a resin composition having extremely low transparency and mechanical strength was obtained. Next, when a partially aromatic nylon having a barrier property was blended, a resin composition having relatively good thermoplasticity and gas barrier properties was obtained. Due to the significant inhibition of biological attack by microorganisms, little or no biodegradability was observed in the resulting resin composition.

The inventors of the present invention have further studied diligently, and surprisingly, when blended with pullulan, a saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVOH) as a thermoplastic resin, excellent thermoplasticity is obtained. And a gas barrier having a gas barrier, and furthermore, when buried in the soil as waste, shows a readily disintegrable property that the microorganism is rapidly disintegrated by soil microorganisms. all right.

A blend of a water-soluble polysaccharide and EVOH is described in JP-A-2-20564, but not only for pullulan but also for the purpose of imparting thermoplasticity to the aforementioned biodegradable resin. No mention is made of the development of the excellent gas barrier properties of the present invention. Therefore, it can be said that the resin composition of the present invention is novel.

The pullulan used in the present invention is sucrose, glucose
Sticky polysaccharides produced by fungal species such as pullularia pullulans using a monosaccharide or disaccharide as a carbon source, such as maltotriose, maltotriose, which comprises α-1,4 linkages
Is a polymer obtained by repeatedly polymerizing at its terminal by α-1,6 bonds, and the degree of polymerization is about 100 to 5,000. Its structural formula is as follows:

[0012]

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The EVOH used in the present invention has an ethylene content of 20 to 65 mol%, preferably 25 to 60 mol%,
The degree of saponification of the vinyl acetate component is 90% or more, preferably 96%.
% Or more of a saponified ethylene-vinyl acetate copolymer. When the ethylene content is 20 mol% or less, the molding temperature becomes close to the decomposition temperature, and molding becomes difficult. On the other hand, when the ethylene content exceeds 60 mol%, the gas barrier
It is not preferable because the property is lowered. Further, EVOH having a degree of saponification of the vinyl acetate component of less than 96%, particularly less than 90% is not preferred because a gel-like substance is easily generated and the gas barrier property is low. The EVOH may be copolymerized with propylene, butylene, a vinylsilane-based compound, a vinylpyrrolidone-based compound, or a plasticizer, a heat stabilizer, an ultraviolet absorber, an antioxidant, a colorant, a filler, or the like, as long as the effects of the present invention are not impaired. -Can be freely blended.

The blending ratio of the resin composition of the present invention is such that pullulan is 90 to 10% by weight and EVOH is 10 to 90% by weight.
% By weight. If the amount of pullulan exceeds 90% by weight or the amount of EVOH is less than 10% by weight, the thermoplasticity of the composition is lost, and melt molding becomes impossible. On the other hand, 10% by weight of pullulan
If less or the EVOH exceeds 90% by weight,
The composition loses its biodegradability. The preferred compounding ratio is 30-90% by weight of pullulan and 10% of EVOH.
７０70% by weight. More preferably, the pullulan is 50-
90% by weight, EVOH is 10 to 50% by weight.

In the present invention, a plasticizer may be freely added in order to increase the moldability and flexibility of the resin. Examples of plasticizers include polyethylene glycol, ethylene glycol, diglycerin, glycerin, 1,3- and 1.4-
From butanediol, 1,2-propylene glycol, sorbitol, ε-caprolactam, urea, toluenesulfonic acid amide, rauramide, acetamido, formamide, dimethylsulfoxide, dioctylphthalate, dibutylphthalate, water, etc. One or two selected
The seeds are used in a mixture. Preferably, glycerin, water, urea and the like are used.

Further, the resin composition of the present invention may be freely blended with a heat stabilizer, an ultraviolet absorber, an antioxidant, a vegetable oil, a coloring agent and the like as long as the effects of the present invention are not impaired.

As a means for compounding each component to obtain the resin composition of the present invention, a ribbon blender, a high-speed mixer-conider, a mixing gall, an extruder, an intensive mixer, and the like are used. The resin composition of the present invention can be used to obtain any molded product (eg, film, sheet, various containers, various injection molded products) using a well-known extruder, injection molding machine, press molding machine and the like.

Although there is no particular limitation on the example of the molded product,
Films, sheets, cups, trays, bottles, tubes, capsules for drugs, etc., agriculture as a food packaging material as applications that take advantage of the gas barrier properties and easy disintegration by living organisms, which are the characteristics of this composition. It is suitably used as a carrier for agricultural chemicals as a use.

When the molded article is discarded after being used, the decay starts immediately after being dumped in a garbage collection area, similarly to general garbage. However, in order to enhance the effect of decay by microorganisms in the soil, A landfill method is preferred. Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0020]

Example 1 70% by weight of pullulan (PF-20 manufactured by Hayashibara Co., Ltd.)
10 parts by weight of glycerin and 10 parts by weight of water were added to 100 parts by weight of a composition composed of 30% by weight of an EVOH having an ethylene content of 44 mol% and a saponification degree of 99%, and these were blended with a Hensyl mixer. Using a single screw extruder having a full-flight screw with a screw diameter of 40 mm and L / D = 26, melt kneading was performed, and a strand was obtained at an extrusion temperature of 130 ° C. from a pellet die attached to the tip of the extruder. Pelletization was continued using a pelletizer. The pellets were extruded at a temperature of 140 ° C. and a thickness of 50 μm using a film forming apparatus having a coat hanger die of 550 mm width attached to the extruder.
Was obtained.

The film was stretched using a tensile tester at a sample width of 15 mm and a tensile speed of 500 mm / min, and the strength and elongation at tensile break were measured. Table 1 shows the results. The film was further subjected to 20 ° C., 65% R.D.
H. The oxygen transmission coefficient was measured using an oxygen barrier measuring device manufactured by Mocon under the conditions described above. Table 1 shows the results. For disintegration against microorganisms, the film was treated in standard activated sludge in 3
The state of the film after being stored at 5 ° C. for 6 months was evaluated in the following four steps, and the results are shown in Table 1. A: severely damaged B: considerably damaged C: slightly damaged D: unchanged

Examples 2 to 3 Evaluation was performed under the same conditions as in Example 1 except for the conditions shown in Table 1. Table 1 shows the results.

Comparative Examples 1 to 3 Evaluation was performed under the same conditions as in Example 1 except for the conditions shown in Table 1. Table 1 shows the results.

[0024]

[Table 1]

[0025]

According to the present invention, there is provided a resin composition having good thermoplasticity, easy disintegration by microorganisms in the soil, and gas barrier properties. A film obtained from the resin composition has a physical property which can sufficiently withstand use when used. When it is buried in the soil as waste after use, it is immediately destroyed by microorganisms present in the soil, and loses its shape, physical strength, and the like.

Claims (1)

(57) [Claims] 1. A gas barrier easily collapsible resin comprising 90 to 10% by weight of pullulan, 10 to 90% by weight of a saponified ethylene-vinyl acetate copolymer having an ethylene content of 20 to 65 mol% and a saponification degree of 90% or more. Composition.