JP3066138B2 - Easily collapsible multilayer body - 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 disintegrable multilayer having excellent 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 the waste treatment facility or landfill.

[0003] Above all, studies on a thermoplastic resin composition having biodegradability by blending a relatively inexpensive and completely biodegradable starch with a thermoplastic resin as an easily disintegrating agent have been actively conducted. (Japanese Patent Application Laid-Open Nos. 2-142228 and 3-33333). Biodegradable resins such as aliphatic polyesters have also been used.

[0004]

However, molded articles obtained from these compositions or biodegradable resins, such as films, have insufficient gas barrier properties.

An object of the present invention is to provide an easily disintegrable multilayer body having excellent gas barrier properties.

[0006]

SUMMARY OF THE INVENTION The above object is, ethylene-containing
An easily collapsible laminate having an ethylene-vinyl alcohol copolymer (EVOH) layer having a content of less than 20 mol% and a biodegradable or photodegradable resin layer, and further containing a plasticizer.
Ethylene-vinyl alcohol copolymer layer and biodegradation
This is achieved by an easily collapsible multilayer body having a water-soluble or photodegradable resin layer .

In the present invention, the gas barrier property is excellent due to the presence of the EVOH layer, and the entire multilayer body is easily disintegrated because the biodegradable or photodegradable resin layer is in contact with one or both sides of the EVOH layer. It will be excellent in property.
Here, easy collapse means that when a multilayer body is buried in soil,
Alternatively, it refers to the ability to lose its shape and mechanical strength when exposed to sunlight.

[0008] The ethylene content of the EVOH used in the present invention is less than 20 mol% from the viewpoint of easy disintegration.
Is necessary. Ethylene content is 3 mol% or more
It is preferably 3 to 14 mol%, most preferably 5 to 14 mol%.
12 mol%. When the ethylene content is less than 3 mol%, the sufficient strength can not be obtained for practical use when formed as a film, also tend easily disintegratable also not sufficient.

The saponification degree of the vinyl ester component of EVOH is preferably at least 50%. From the viewpoint of thermal stability, it is preferably 80% or more, and more preferably 90%
It is preferable that it is above. If the degree of saponification is less than 50%, the thermal stability is reduced and a large amount of gel is generated at the time of molding. Further, from the viewpoint of hot water solubility, the saponification degree is preferably 50 to 95%, more preferably 60 to 95%. EVOH is a saponified copolymer of ethylene and vinyl ester. Here, vinyl acetate is a typical example of vinyl ester. Other fatty acid vinyl esters (eg, vinyl pivalate) can also be used. . In addition, EVOH, olefins having 3 or more carbon atoms such as propylene, (meth) acrylic acid, vinylsilane-based compounds (vinyltrimethoxysilane, vinyltriethoxysilane, etc.), vinylpyrrolidone-based compounds can be used as long as the object of the present invention is not impaired. It is free to copolymerize the third component such as. Further, EVOH having an alkyl group having 4 to 50 carbon atoms at the terminal and / or side chain, EVOH having a part of hydroxyl group oxidized, EVOH having an aliphatic polyester grafted, and ionic group (carboxylic acid EVOH having a group or a salt thereof, a sulfonic acid group or a salt thereof, an ammonium group, and the like. In addition, the intrinsic viscosity of EVOH [solvent water / phenol 1
5/85 (weight ratio), 30 ° C.] is 0.05 to 0.2 liter / g, preferably 0.07 to 0.15 liter / g.
g.

It is particularly preferable that the EVOH used in the present invention is soluble in hot water because it has an effect of promoting the easy disintegration of the EVOH. Here, the term "soluble in hot water" means a property of substantially completely dissolving when immersed in hot water of 95 ° C for 1 minute. EVOH is preferably thermoplastic because it can be melt co-extruded with other resins.

Further, in order to further increase the moldability and flexibility of the resin in the EVOH layer in the multilayer body of the present invention,
It is free to add other additives, for example, plasticizers such as water, glycerin and the like. Examples of plasticizers are polyethylene glycol, ethylene glycol, diglycerin,
Glycerin, 1,3- and 1.4-butanediol,
One or two or more selected from 1,2-propylene glycol, sorbitol, ε-caprolactam, urea, toluenesulfonic acid amide, laurylamide, acetamide, formamide, dimethylsulfoxide, dioctyl phthalate, dibutyl phthalate, water and the like are mixed. Used. Preferably, glycerin, water, urea and the like are used.

Further, fillers (talc, clay, mica, cellulose fibers, PVA fibers, etc.), heat stabilizers, ultraviolet absorbers, antioxidants, etc. are provided in each layer of the multilayer body of the present invention as long as the effects of the invention are not impaired. It is also free to blend vegetable oils, coloring agents and the like.

Examples of the molded product obtained from the multilayer body of the present invention are not particularly limited, but the molded product is discarded after being used for a certain period of time, such as cups, bottles, trays, and agricultural materials as food containers. Sheets, piles, mulch (multi-film), planters, containers or carrier materials for pesticides, fertilizers, soil conditioners, etc., ties as daily necessities, toys for children, trash cans, cushioning materials for industrial use, packing, various types Examples include containers and colostomy bags.

When the molded article is discarded after being used, collapse begins immediately after dumping in a garbage collection site similar to general garbage. However, in order to enhance the effect of microorganisms in the soil, A landfill method is preferred.

In the present invention, the biodegradable resin layer provided on one or both sides of the EVOH layer includes proteins (gelatin, collagen), polypeptides, polyesters (polyadipade, polylactone, aliphatic polyester, aliphatic polyesteramide), Thermoplastic resin containing ether, polyurethane, polystyrene, and polysaccharide (starch, cellulose, chitin, chitosan, etc.) ｛Polyolefin (polyethylene, etc.), polystyrene, vinyl alcohol-based resin (ethylene content 25 to 6)
A film or sheet obtained from a thermoplastic resin such as 5 mol% EVOH) or an ethylene-acrylic acid copolymer blended with a polysaccharide is typical. As the photodegradable resin layer, a copolymer of ethylene and carbon monoxide, methyl vinyl ketone and ethylene,
Films or sheets obtained from copolymers of styrene, vinyl chloride, methyl acrylate, etc., and various thermoplastic resins blended with photodegradable masterbatches (polyethylene grafted with methyl vinyl ketone and a small amount of methyl styrene) Is a typical example.

The biodegradable or photodegradable resin layer is made of EV
An OH layer can be provided on one side or both sides, or an EVOH layer can be provided on both sides of a biodegradable or photodegradable resin layer. When producing these multilayer bodies, an adhesive, preferably a biodegradable adhesive, can be used if necessary. Examples of the adhesive include a polyurethane resin, a starch resin, and an unsaturated carboxylic acid or an anhydride thereof (maleic anhydride or the like) containing the resin or the olefin polymer or copolymer [polyethylene.
10 degree polyethylene (LDPE), linear low density polyethylene (LLDPE), ultra low density polyethylene (SLDP)
E)｝, ethylene-vinyl acetate copolymer, ethylene-
(Meth) acrylic acid ester (methyl ester or ethyl ester) copolymer]. These adhesives are used as interlayer adhesives or compounded in at least one of the layers.

Examples of the method for obtaining a multilayer body include extrusion lamination, dry lamination, coextrusion lamination, coextrusion sheet molding, coextrusion pipe molding, coinjection molding, and the like.
Solution coating method and the like can be mentioned.

The thickness of each layer of the multilayer body is not particularly limited, but the EVOH layer has a thickness of 1 to 300 μm, preferably 5 to 300 μm.
The ratio to the total thickness of the EVOH layer is preferably 2 to 30%, more preferably 2 to 25%. Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[0019]

Example 1 Among the EVOHs used in the present invention, the easy disintegration of a single EVOH having a low ethylene content, which is particularly excellent in easy disintegration, was examined. Ethylene content 7 mol%, saponification degree 99.7
% EVOH was used as a solvent in a mixed solution of water and propanol to obtain an EVOH solution having a concentration of 10% by weight. Bring the solution to a temperature of 7
The solvent was evaporated by applying the solution on a rotating drum adjusted to 5 ° C. to obtain a uniform film having a thickness of 15 μm.

The film was cut into a size of 15 × 100 mm, immersed in hot water adjusted to 95 ° C. for 1 minute, and examined for solubility in hot water. The results are shown first. The hot water solubility was evaluated in three stages as described below. ○ ・ ・ ・ Completely dissolved △ ・ ・ ・ Swelled and separated × ・ ・ ・ Invariant

The film was cut out in an amount of 0.2 g and immersed in 100 ml (ml) of a liquid medium containing 3% of polyvinyl alcohol (PVA) previously sterilized. 1 ml of a PVA-degrading bacterial solution (milliliter (m)) previously grown on this medium by shaking for 3 days in a liquid medium containing 0.3% of PVA.
l), and adjust the pH to 7 to 7.5 on the way.
After shaking for a week, the change in weight of the film was determined by the following equation and is shown in Table 1. The shaking conditions are 120 rpm (30 ° C).
It is.

Weight change of film (%) = (weight of film before culture−weight of film after 2 weeks of culture) × 100 weight of film before culture The weight of the film was measured at 20 ° C. and 50% RH at 48%. This is a value measured after standing for a long time.

The composition of the liquid medium containing 0.3% of PVA (PH = 7.5) is as follows. PVA (polymerization degree 1700, saponification degree _{99.9%) 0.3% NH 4 NO} 3 0.1% KH 2 PO 4 0.02% K 2 HPO 4 0.1% MgSO 4 · 7H 2 O 0.02 % NaCl 0.01% CaCl ₂ .2H ₂ O 0.01% FeSO ₄ .7H ₂ O 0.001% Peptone 0.005% ext. 0.005% pyrroloquinoline quinone 1 μg / ml

Examples 2 to 3 The same conditions as in Example 1 were carried out except as shown in Table 1. Table 1 shows the results.

Example 4 EVOH having an ethylene content of 10 mol% and a saponification degree of 90%
90 parts by weight and 10 parts by weight of glycerin as a plasticizer are blended, melt-kneaded using a single screw extruder having a full flight screw having a screw diameter of 40 mm and L / D = 26, and a pellet die attached to the tip of the extruder. The extruder was made into a strand at an extruder temperature of 180 ° C. and then pelletized using a pelletizer. The above-mentioned pellets were subjected to a three-type five-layer coextrusion apparatus to prepare a multilayer film. The film was composed of a polycaprolactone resin layer (thickness of each layer is 30 μm), an adhesive resin layer (thermoplastic polyurethane layer) (thickness of each layer was 10 μm), and an intermediate layer formed of the above E layer.
VOH layer (thickness: 20 μ).

The obtained film is placed in soil (below 5 to
10 cm), and the state of the film after 6 months was evaluated for easy disintegration in the following four stages. The results are shown in Table 2. A: severely damaged B: considerably damaged C: slightly damaged D: unchanged

Example 5 A film was obtained under the same conditions as in Example 4, except that polycaprolactone was replaced with polystyrene containing 20% by weight of starch. Table 2 shows the results.

Example 6 Instead of the EVOH of Example 4, an ethylene content of 12 mol
A film was obtained under the same conditions as in Example 4 except that EVOH having a saponification degree of 30% and a saponification degree of 99.5% was used. Table 2 shows the results. In addition, the breaking strength and the breaking elongation of the multilayer film obtained in Example 4-5 showed sufficiently practical values.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

The multilayer body of the present invention has excellent gas barrier properties and easy disintegration properties, and the molded article obtained from the multilayer body of the present invention can be rapidly treated by microorganisms when it is landfilled as waste after use. , And its shape, strength, etc. disappear.

Continuation of the front page (56) References JP-A-4-90339 (JP, A) JP-A-5-4311 (JP, A) Tables JP-A-5-505354 (JP, A) (58) Fields surveyed (Int) .Cl. ⁷ , DB name) B32B 1/00-35/00 B65D 65/40

Claims (5)

(57) [Claims] An easily collapsible multilayer body having an ethylene-vinyl alcohol copolymer layer having an ethylene content of less than 20 mol% and a biodegradable or photodegradable resin layer. 2. An ethylene-vinyl alcohol containing a plasticizer.
A copolymer layer and a biodegradable or photodegradable resin layer.
An easily collapsible multilayer body. 3. The easily collapsible multilayer body according to claim 1, wherein the ethylene-vinyl alcohol copolymer is soluble in hot water. 4. An ethylene-vinyl alcohol copolymer layer.
The weight change rate is 80.4% or less.
An easily disintegrable multilayer body according to any of the above items. 5. An ethylene-vinyl alcohol copolymer layer,
Adhesive layer provided between biodegradable or photodegradable resin layers
The easily disintegrable multilayer according to any one of claims 1 to 4,
body.