JP2002166503A - Multilayered molded object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayered molded object comprising a hydrolyzable material rapidly decomposable after disposal while suppressing the reduction of the mechanical strength of a base material at the time of distribution or use. SOLUTION: The multilayered molded object is obtained by bonding peelable moisture barrier layers to both surfaces of a hydrolizable base material layer. Hydrolysis or biodegrability can be accelerated by peeling the moisture barrier layers at the time of disposal after distribution or use.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded article made of a hydrolyzable resin having sufficient mechanical strength and stability and decomposing quickly after disposal.

[Prior art]

[0002] Biodegradable resins are characterized by being degraded by microorganisms by composting or landfilling in the soil. In practice, however, many resins are highly hydrolyzable and need to be practically used during use. There is a problem of losing the required mechanical strength. For this reason, the application field was limited to a part of the packaging material having a short life cycle.

On the other hand, in recent years, the problem of garbage waste has become more serious, and it has been desired to apply biodegradable and hydrolyzable resins to long-life products such as large home appliances. TV set,
Large parts such as housings and trays for air conditioners and refrigerators are often made of ABS or polystyrene resin. However, when these resins are recycled horizontally, the quality and strength are reduced. It is difficult. However, if the hydrolyzable resin can be used for these large home appliances, the problem of garbage waste can be reduced, but as described above, practical strength is lost during use. There was a problem.

[0004] While the molded article of the resin having hydrolyzability is distributed as described above, it is necessary to maintain the shape and physical properties of the molded article. On the other hand, it is desired that the molded article be rapidly decomposed after use. Various attempts have been made.

[0005] For example, JP-A-10-182990 discloses an example in which a hydrolysis inhibitor is kneaded with a resin in advance and molded to extend the life cycle of a product. However, this method has the disadvantage that hydrolysis is slow even at the time of disposal, and the toxicity of the hydrolysis inhibitor has been regarded as a problem.

On the other hand, there is known a multilayer film in which a layer having a low moisture permeability is provided on a surface layer for protecting the contents from humidity (Japanese Patent Application Laid-Open No. H11-49129). Therefore, when the surface layer itself does not have biodegradability, there is a problem that it is not suitable for composting.

Further, a layer having low moisture permeability is used as an inner layer,
As a multilayer structure having a decomposable resin provided on the surface layer, for example, JP-A-5-84874 discloses an ethylene-vinyl alcohol copolymer layer, particularly an ethylene-vinyl alcohol copolymer having an ethylene content of 3 to 24 mol%. An easily disintegrable multilayer having a layer and a biodegradable or photodegradable resin layer is disclosed. The present invention is an easily disintegrable multilayer body having a biodegradable or photodegradable resin as an outer layer, and when buried in soil as waste after use, is rapidly disintegrated by microorganisms, and its shape, strength, etc. Disappears. Therefore, not only the structure is different from that of the present invention, but the ethylene-vinyl alcohol copolymer in the inner layer has low hydrolyzability and biodegradability, and may be concentrated in the subsequent decomposition treatment step. In addition, such a film has a problem in that the hydrolyzable resin in the surface layer contains moisture and is decomposed with time, thereby causing stains and impairing the appearance.

Further, Japanese Patent Application Laid-Open No. 10-138371 discloses that
A multilayer hollow container excellent in oxygen gas barrier properties and carbon dioxide gas barrier properties is disclosed, which is suitable as a container for those requiring a processing step under high temperature and high humidity such as retort sterilization and those requiring long-term storage. . The present invention relates to a gas-barrier multilayer hollow container having a multilayer wall structure in which a thermoplastic resin layer is laminated on at least one surface of a layer formed from a polyglycolic acid copolymer, and a blow molding method. And a method for producing the same. However, this is also a technology conceived with protection of the contents in mind, and is a multilayer body in which a gas barrier layer is disposed in an inner layer and a thermoplastic resin such as a biodegradable resin is disposed in an outer layer.
The structure is different from the present invention. In addition, there is no mention of any issues with extending product life or disposal. In this case, as in the above case, the outer layer was stained with time, and the appearance was impaired.

As described above, although a multilayer structure of a hydrolyzable resin is known, a hydrolyzable resin is used as an inner layer, and a layer for protecting the hydrolyzable resin is provided on both surfaces. There has been no known case of suppressing the reduction of the mechanical strength of the hydrolyzable resin. Furthermore, there is no example that solves the problem at the time of disposal, and no application example of a large molded product such as an injection molded product has been known.

[0010]

The problem to be solved by the present invention is to reduce the shape and physical properties of a substrate layer made of a hydrolyzable material during use, and in particular, to reduce the decrease in mechanical strength, and to reduce the (1) To provide a molded body made of a hydrolyzable material capable of rapidly hydrolyzing and reducing the environmental load. Further, it is to prevent generation of stains caused by the surface of the molded body made of the hydrolyzable material containing moisture.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems, and as a result, it has been found that both sides of a substrate layer made of a hydrolyzable material can be peeled off, By laminating a moisture-blocking layer made of a resin having a low resin content, it is possible to suppress a decrease in the shape and mechanical strength of the base material, to prevent the surface from being stained and to impair the appearance, and to dispose of the surface layer when disposed. Completed the present invention by finding a multilayer molded article that can be quickly decomposed by peeling off the blocking layer, and furthermore, finding that the surface of the molded article made of a hydrolyzable material prevents the occurrence of stains caused by containing water. I came to. That is, the present invention

[0012] (1) on both sides of the base layer made of hydrolyzable material, the moisture permeability ^{50g / (m 2 · day ·} 25μ
m) a multilayer molded article having a moisture barrier layer comprising the following resin laminated:

(2) The base material layer is made of at least one hydrolyzable material selected from the group consisting of a hydrolysable resin, starch and its derivatives, and cellulose and its derivatives ( The multilayer molded article according to 1),

(3) The moisture barrier layer is made of polyethylene, polypropylene, polyethylene vinyl alcohol copolymer, polyvinyl alcohol, polyvinyl chloride,
The multilayer molded article according to (1) or (2), which is at least one hydrolyzable material selected from the group consisting of nylon.

(4) The tensile strength of the moisture barrier layer is 20 to
The multilayer molded article according to any one of (1) to (3), which is 200 MPa.

(5) The adhesive strength between the base material layer and the moisture barrier layer is 5
(1) characterized in that it is up to 70 N / 15 mm.
(4) The multilayer molded article according to any one of the above,

(6) A moisture barrier layer is laminated on both sides of the base material layer by using an adhesive.
(5) The multilayer molded article according to any one of the above,

(7) The adhesive strength between the substrate layer and the moisture barrier layer is 1
The multilayer molded article according to (6), which has a thickness of 0 to 30 N / 15 mm.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The multilayer molded article of the present invention has a water vapor transmission rate of 50 g on both sides of a substrate layer made of a hydrolyzable material.
The basic configuration is a multilayer molded body in which a moisture barrier layer (hereinafter, sometimes simply referred to as a “barrier layer”) made of a resin having a thickness of / (m ² · day · 25 μm) or less is laminated.

First, the resin used for the barrier layer of the present invention will be described. Although the resin used in the blocking layer of the present invention is water permeability is ^{50g / (m 2 · day ·} 25μm) following resins, ^2-preferably 0.5 to 50 g / (m
day · 25 μm), more preferably 0.5 to 30 g /
(M ² · day · 25 μm), more preferably 0.5
２０20 g / (m ² · day · 25 μm) or less. The moisture permeability within this range depends on the thickness of the layer, but the exposure of moisture to the substrate layer can be extremely suppressed, so that the hydrolysis is suppressed and the decrease in the mechanical strength of the substrate layer is suppressed. be able to. Furthermore, the contamination of the surface of the molded article caused by the base layer containing moisture can be suppressed.

Specific examples of the resin that can be used for such a barrier layer include polyethylene, polypropylene, polyethylene vinyl alcohol copolymer, polyvinyl alcohol, polyvinyl chloride, and 6-nylon. Is polyvinyl chloride or 6-nylon. These can be used alone or in multiple layers. When it is necessary to use another resin as a surface layer from the viewpoint of surface characteristics, a layer formed of the resin and a layer formed of the resin having low moisture permeability of the present invention are multilayered. Can be used as a surface layer.

Further, it is preferable to use a resin obtained by kneading a water-repellent agent or the like with the above-mentioned resin in order to suppress moisture permeability in the blocking layer. Examples of such a water repellent include silica and fluororesin. Also, 50 g / (m
Even if the resin is ² · day · 25 μm or more, 50 g / (m ² · day · 25 μm) can be obtained by kneading with the water repellent.
If it is below, it may be used as a moisture barrier layer. Further, as an additive that prevents water repellency and permeation of water, inorganic substances such as silicon dioxide, and carbodiimides that can chemically supplement water can also be used effectively.

Further, the resin used for the blocking layer may further include:
An inorganic substance such as a flame retardant or a pigment may be added. Flame retardants are often used especially as housing materials for home appliances. Pigments may also be included for purposes such as coloring the product.

Next, the hydrolyzable material used for the substrate layer will be described. The first material used for the base material layer is
It is a hydrolysable resin, and specific examples thereof include aromatic polyesters such as polyethylene terephthalate and polyamides such as nylon. In the present invention, as the hydrolyzable resin, a hydroxycarboxylic acid-based polymer, specifically, polylactic acid, polyglycolic acid, poly-
β-hydroxybutyrate, poly-β-hydroxyvalerate, poly-γ-butyrolactone, poly-δ-valerolactone, poly-ε-caprolactone, and the like,
Among these, at least two or more copolymers and mixtures are included.

Further, a polyester comprising a diol and a dicarboxylic acid can be used as the base material layer. However, as the polyester comprising a diol and a dicarboxylic acid used in the present invention, polyethylene succinate having a melting point of room temperature or higher, polypropylene succinate, polytrimethylene succinate, polybutylene succinate,
Polyethylene adipate, polypropylene adipate,
Polytrimethylene adipate, polybutylene adipate, polyethylene sebacate, polytetramethylene sebacate, polyhexamethylene sebacate, cyclohexane dimethanol / succinic polyester, cyclohexane dimethanol / adipate polyester, ethylene glycol cyclohexane dicarboxylate polyester,

Aliphatic polyesters such as 1,4-butanediol / cyclohexanedicarboxylic acid polyester, 1,6-hexanediol / cyclohexanedicarboxylic acid polyester, or cyclohexanedimethanol / cyclohexanedicarboxylic acid polyester; or polyethylene terephthalate, polybutylene terephthalate,
Alternatively, aromatic polyesters such as polytetramethylene glycol / terephthalic acid polyetherester and the like. In addition to these, the present invention includes various moldable polyesters by a combination of a diol and a dicarboxylic acid.

The diol component serving as a raw material of the above-mentioned polyester includes ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12
-Dodecanediol, 1,4-cyclohexanedimethanol, propylene glycol, 1,3-butanediol, 1,2-butanediol, neopentyl glycol, 3,3-diethyl-1,3-propanediol,
3,3-dibutyl-1,3-propanediol, 1,2
-Butanediol, 1,2-pentanediol,

1,3-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 1,4-pentanediol, 1,2-hexanediol, 1,3-
Hexanediol, 1,4-hexanediol, 1,5
Diols such as -hexanediol, n-butoxyethylene glycol, cyclohexanedimethanol, hydrogenated bisphenol A, diethylene glycol having ether oxygen, dipropylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and aromatics Xylylene glycol having a structure, phenylethylene glycol, or the like can be given.

On the other hand, the dicarboxylic acid component as a raw material of the above-mentioned polyester includes fumaric acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, cyclohexanedicarboxylic acid, or Dimer acid, aliphatic dicarboxylic acid such as hydrogenated dimer acid, or phthalic acid, terephthalic acid,
An aromatic dicarboxylic acid such as isophthalic acid or naphthalenedicarboxylic acid can be used. These dicarboxylic acids are not particularly limited thereto, and may have an unsaturated bond. The polyester used in the present invention includes a copolymerized polyester obtained by using at least one kind of each of the above-mentioned diols and dicarboxylic acids and by a known and common method.

Although the molecular weight of the polyesters used in the present invention is not particularly limited, the number average molecular weight is generally 30,000 or more, preferably 30,000 to 4,000.
0000, more preferably 50,000 to 30,0.
000. In order to obtain such a high molecular weight polyester, it is preferable to increase the molecular weight by using an acid anhydride or a polyfunctional isocyanate. An acid anhydride is a carboxylic acid anhydride having two or more carboxyl groups in one molecule. Specific examples of the carboxylic anhydride include, for example, succinic anhydride, cyclohexanedicarboxylic anhydride, phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic dianhydride or a mixture thereof.

Here, the polyfunctional isocyanate is 2
A compound having two or more isocyanate groups. Particularly, those having only an isocyanate group as the type of the functional group are preferable. For the purpose of obtaining an urethane bond-containing polyester having a substantially linear structure, a bifunctional isocyanate is preferred.

Specific examples of the bifunctional isocyanate include, for example, hexamethylene diisocyanate, 2,4
-Tolylene diisocyanate, 2,5-tolylene diisocyanate, toluene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate,
Examples include 1,5-naphthylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, or mixtures thereof.

Further, as the polyfunctional isocyanate, those having three or more functionalities can be used. In this case, the obtained polymer chains become star-shaped. In order to obtain such a product, pentaerythritol is modified with a bifunctional isocyanate, and a polyhydric alcohol is represented by a bifunctional isocyanate.
Compounds modified with functional isocyanates are included.

As the polyfunctional isocyanate used in the present invention, several kinds of polyfunctional isocyanates can be used in combination.
When used in combination with a functional isocyanate, it can be reacted and gelled without gelling.

The reaction between the polyester and the carboxylic acid anhydride or di- or triisocyanate may be carried out by mixing the carboxylic acid anhydride or the isocyanate with a mixture of two kinds of polyesters and stirring them in a molten state for a short time, or A method in which the polyester is added again to the polyester obtained by polymerization and melt-mixed may be used.

Particularly preferred in the case of isocyanate is a method in which both the polyester and the isocyanate are dissolved in a cosolvent and the mixture is reacted by heating. This allows the isocyanate to be very uniformly dispersed in the aliphatic polyester.

The temperature at which the polyester is mixed with the carboxylic anhydride or isocyanate is usually 70 ° C.
To 220 ° C, preferably 100 ° C to 190 ° C.
In the reaction of the polyfunctional isocyanate, N, N
-It is preferable to use an ester polymerization catalyst such as dimethylaniline, tin octoate, dibutyltin dilaurate, tetraisopropyl titanate, or a urethane catalyst.

The above carboxylic anhydrides and polyfunctional isocyanates can be mixed and used as required. The amount of these used is preferably 0.01% by weight to 5% by weight of the aliphatic polyester, and more preferably 0.1% by weight to 1% by weight.

Further, in the present invention, a copolyester of a polycondensed polyester of a diol and a dicarboxylic acid and a ring-opening polymerizable monomer such as lactone or lactide can also be used. The copolymerized polyester can be obtained by copolymerization of a ring-opening polymerizable monomer and a polyester with a ring-opening polymerization catalyst in the presence of the polyester, or can be obtained by transesterification of the polyesters.

Specifically, a polyester copolymer comprising a polyhydroxycarboxylic acid, a diol and a dicarboxylic acid is preferred to have a large amount of the polyhydroxycarboxylic acid since the heat resistance as a molded article is improved. In particular, since the heat resistance of polylactic acid decreases as the copolymerization ratio of polyester increases, the ratio of polylactic acid: polyester is 97: 3 to 70:
A ratio of 30 is preferred.

The polyester which can be used for the copolymer preferably has a hydroxyl group at both terminals or one terminal. When the polyester alone is used as described above, the polyester needs to be solid.However, in the case of a copolymer with polyhydroxycarboxylic acid or a cyclic monomer of polyhydroxycarboxylic acid, the copolymer is solid. As long as it is sufficient, the polyester may be particularly liquid.

Next, starch is mentioned as a second material used for the base material layer. Starch is a natural material with high biodegradability, but has a disadvantage in that it has high water absorption. In the present invention, this disadvantage can be improved by the barrier layer. The starches that can be used include those in which hydroxyl groups have been partially esterified or those in which all have been esterified.

Further, as the third material used for the base material layer, there may be mentioned cellulose and its derivatives. Specifically, acetylcellulose is preferred.

The hydrolyzable material used for the base layer is a mixture of two or more materials selected from the group consisting of hydroxycarboxylic acid polymers, polyesters composed of diols and dicarboxylic acids, starches and celluloses. The resulting composition may be. However, the mixing ratio is not particularly limited, and can be changed in any range according to desired mechanical properties.

In the multilayer structure of the present invention, the barrier layer and the base material layer may be bonded with an adhesive if necessary. The adhesive to be used is not particularly limited as long as it can sufficiently adhere the barrier layer and the base material layer. However, an adhesive which is easily peelable is preferable. Specifically, a polyester / urethane-based adhesive, a polyamide-based adhesive, a polyolefin-based adhesive, and the like can be given. When the surface layer is a non-hydrolysable resin, the peeling may be not only mechanical peeling but also chemical peeling using alkali hydrolysis.

Next, the multilayer molded article of the present invention will be described. As shown in FIG. 1, the multilayer molded article of the present invention has a water vapor transmission rate of 50 on both surfaces of a base layer made of a hydrolyzable material.
The basic configuration is a multilayer molded body in which a moisture barrier layer made of a resin of g / (m ² · day · 25 μm) or less is laminated.
Further, if the outermost layer is a moisture barrier layer, these layers may be alternately and repeatedly laminated.

The thickness of the substrate layer is preferably 0.03 mm
To 50 mm, more preferably 0.1 mm to 2 mm. Since the mechanical strength varies depending on the application, the mechanical strength of the substrate layer is not particularly limited even in the present invention, but generally, when used as a sheet, film, etc., the tensile strength at room temperature Is 80 MPa or more, generally 80 to 130 MPa, and a material having a tensile elongation of 50 (%) or more, generally 50 to 100 (%). Further, in a molded article such as an injection molded article, a vacuum molded article, a vacuum pressure molded article, a blow molded article, an extrusion molded article, a material having a tensile elastic modulus of 0.9 GPa or more and a bending elastic modulus of 0.6 GPa or more is used. .

The moisture barrier layer has a thickness of 0.01 to 0.5 mm.
Is preferably, and more preferably 0.02 to 0.25 mm
It is. Since the required mechanical strength varies depending on the application, the mechanical strength of the barrier layer is not particularly limited in the present invention. However, when the barrier layer is mechanically peeled off from the base material layer at the time of disposal, the tensile strength at room temperature is 80 MPa or more, generally 80 to 130 MPa, and the tensile elongation is 50 (%) or more, generally 50%. ~ 100
(%) Is desirable. The adhesive strength between the base material layer and the barrier layer is not particularly limited, but when mechanically peeled off, it is 5 to 70 N / 15 mm, preferably 10 to 30 N / 15.
It is desirable to be 15 mm.

In order to further adjust the adhesive strength, the base material layer and the barrier layer may be bonded using an adhesive, but the adhesive layer (hereinafter, may be simply referred to as an adhesive layer) is used to block moisture. It is preferably thinner than the layer, preferably 0.001-0.
02 mm, more preferably 0.001 to 0.01 mm. In the present invention, both surfaces (front and back) of the substrate layer are completely covered with the moisture barrier layer and the adhesive layer.

By adopting the above-mentioned basic structure, the molded article of the present invention can suppress a decrease in the mechanical strength of the base material layer during molding for a long time. Depending on the application, the minimum required mechanical strength and the time required to maintain that strength are different,
By appropriately adjusting the thickness of the barrier layer and the thickness of the base layer, the type of each material, for example, the half-life of mechanical strength, when the barrier layer is adhered to only one surface of the base layer Can be adjusted 2 to 10 times, preferably 4 to 10 times.

Next, a method for producing the multilayer molded article of the present invention will be described. The base material layer of the present invention can be formed by injection molding, vacuum molding, vacuum pressure molding, blow molding, extrusion molding, or the like. In the case of injection molding, by covering the base material layer with a film or sheet having an adhesive layer, a barrier layer can be formed as a surface layer to form a multilayer. At this time, a film or sheet having heat shrinkage is more preferable because the adhesion to the hydrolyzable material forming the base layer is increased. However, since many hydrolyzable materials have low heat resistance, it is preferable to perform heat shrinkage while fixing the inside to a mold.

As a method for forming the barrier layer, a film such as polyethylene or polyethylene vinyl alcohol copolymer can be bonded to the base layer by lamination. When the surface hardness is required, a method of supplementing the hardness by multi-layer molding a polystyrene sheet or a polyethylene terephthalate sheet on the upper layer of the barrier layer is also possible.

In vacuum forming or pressure forming, a pressure-sensitive adhesive layer is formed on a base material layer sheet, a film of a blocking layer is laminated from above and below to form a multilayer sheet, and then the blocking layer and the base material layer are bonded together. What is necessary is just to integrally mold at the same time. In this case, the melting point and softening point of the resin of the barrier layer and the base layer are important, for example,
With a polystyrene / polyethylene multilayer sheet and polylactic acid, molding can be performed at a temperature of 80 to 100 ° C.

In blow molding and extrusion molding, integral molding is possible by using a die for multilayer blow. In the case of stretch blow, a small injection product called a parison is heated and blown, so that the same multi-layering method as in the case of the above-described injection product can be used during parison molding. If this is stretch-blown, a multilayer molded article is obtained.

In the extruded sheet or film, after forming the base material layer once, a blocking layer and, if necessary, an adhesive layer can be formed by surface lamination. This method is one of the methods that can be easily performed because the sheet can be rolled. In the present invention, lamination processing that can be performed includes thermal lamination and dry lamination.

The multilayer molded article of the present invention can be used as various molding resins. As a packaging material, for example,
The sheet is useful for trays, cups, dishes, blisters, and the like.

Further, it is usefully used as a blow molded product for other uses, and is useful, for example, for shampoo bottles, cosmetic bottles, beverage bottles, oil containers and the like.

Injection molded products include telephones, televisions, radios, air conditioners, personal computers, boomboxes, CD players, printers, vacuum cleaners, refrigerators, VCRs,
It is useful for housing materials for home appliances such as video cameras, plates, cups, cassette tapes, refrigerator trays, stationery such as ballpoint pens, and the like.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

EXAMPLES (Example 1) A polyethylene vinyl alcohol copolymer / polystyrene multilayer sheet was used for a blocking layer, a polyamide-based pressure-sensitive adhesive was used as an adhesive, and polylactic acid ("Ecopla" manufactured by Cargill Dow) was used for a substrate layer. First, polylactic acid was formed into a sheet having a thickness of 0.3 mm. An adhesive layer was vertically coated on the sheet, and a 0.1 mm-thick polyethylene vinyl alcohol copolymer / polystyrene multilayer sheet was laminated on both sides of the barrier layer. This multilayer sheet is
A lunch box was molded by a vacuum pressure molding machine heated to １００100 ° C. (molded product 1).

Example 2 A polyethylene vinyl alcohol copolymer film was used for the barrier layer, a polyolefin-based pressure-sensitive adhesive was used for the adhesive, and a polyhydroxyalkanoate ("Biopol" manufactured by Monsanto) was used for the base layer. First, a pen case was injection molded with a biopole. This case is coated with an adhesive layer on the top and bottom, and a 0.05 mm
A thick polyethylene vinyl alcohol copolymer film was laminated on both sides (molded product 2).

(Example 3) Polyethylene emulsion for the barrier layer, polyolefin-based adhesive for the adhesive, polylactic acid- (propylene glycol dimer acid polyester) block copolymer for the base layer (copolymerization ratio: 85 parts by weight: 15 parts by weight) Was used. First, a polylactic acid block copolymer was injection molded into a parison mold. The parison was coated with an adhesive inside and outside, and a polyethylene was laminated on the barrier layer to a thickness of 0.1 mm. After the drying step, 70
The multilayer blow bottle was formed by heating and stretching blow at ℃. (Mold 3).

Example 4 A polyethylene vinyl alcohol copolymer / polystyrene multilayer sheet was used for the barrier layer, a polyamide adhesive was used for the adhesive, and polyethylene terephthalate was used for the base layer. First, polystyrene was injection molded into a parison mold. This parison is coated with adhesive inside and outside,
Further, polyethylene was laminated on the barrier layer so as to have a thickness of 0.1 mm. After the drying step, it was heated at 70 ° C. and stretch blown to form a multilayer blow bottle. (Molded product 4).

(Comparative Example 1) Polylactic acid ("Ecopla" manufactured by Cargill Dow) was formed into a sheet having a thickness of 0.3 mm. The sheet was heated to 70 to 100 ° C. to form a lunch box with a vacuum press forming machine (molded product 5).

Comparative Example 2 A pen case was injection-molded with polyhydroxyalkanoate (“Biopol” manufactured by Monsanto) (molded product 6).

Comparative Example 3 A polylactic acid- (propylene glycol dimer acid polyester) block copolymer (copolymerization ratio: 85 parts by weight: 15 parts by weight) was injection-molded into a parison mold. After the drying step, the mixture was heated at 70 ° C. and stretch blown to form a blow bottle. (Molded product 7).

Comparative Example 4 Polyethylene terephthalate was injection molded into a parison mold. After a further drying step, 7
It was heated at 0 ° C. and stretch blown to form a blow bottle (molded product 8).

(Comparative Example 5) A two-layer, two-layer sheet having one side of an ethylene-vinyl alcohol copolymer layer and one side of a polylactic acid-glycolic acid copolymer layer was formed by multilayer extrusion. (Molded product 9)

(Comparative Example 6) A two-layer, three-layer sheet having an inner layer of an ethylene-vinyl alcohol copolymer layer and an outer layer of a polylactic acid layer was formed by multilayer extrusion. (Molded product 10)

Test Example 1 Molded products 1 to 10 were heated at 40 ° C.
An exposure test was performed for one year under a constant temperature and humidity of 95% RH. As a result, the molecular weights of the base material layers of the molded products 1 to 3 of Examples 1 to 3 hardly changed, whereas the comparative examples 1
In the molded products 5 to 10 of Nos. 3 to 10, the molecular weight was 20,000 or less, and they were ragged. Further, molded articles 1, 3 which are transparent materials
Had maintained its transparency, but also in 5, 7 to 10, the haze was 60% or more, and the transparency was significantly reduced.

Test Example 2 The molded articles molded in Example 4 and Comparative Example 4 were subjected to a hydrolysis test at 60 ° C. and 95% RH for one year. In the drop test of the molded bottle, the bottle of the molded product 4 was not destroyed and the molded product 8 was destroyed by dropping from a height of 1 m. (Test Example 3) After the tests of Test Examples 1 and 2, the blocking layer was peeled off. By immersing the molded products 1 and 4 in a 10% alkaline solution, the barrier layer and the base material layer were separated. Moldings 2 and 3 were physically peeled. When the base material layers of the molded products 1 to 3 were treated with an automatic composting machine heated to 58 ° C. for one week, they were disintegrated so that the original shape was hardly retained.

According to the present invention, it is possible to provide a molded body made of a hydrolyzable material which can be rapidly hydrolyzed after disposal to reduce the environmental load while maintaining mechanical strength.

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Claims (7)

[Claims] 1. A film having a water permeability of 50 g / (m ² · day · 25 μm) on both surfaces of a substrate layer made of a hydrolyzable material.
A multilayer molded article in which a moisture barrier layer made of the following resin is laminated. 2. The method according to claim 1, wherein the base material layer comprises at least one hydrolyzable material selected from the group consisting of a hydrolysable resin, starch and its derivatives, and cellulose and its derivatives. 2. The multilayer molded article according to 1. 3. The method according to claim 1, wherein the moisture barrier layer is at least one hydrolyzable material selected from the group consisting of polyethylene, polypropylene, polyethylene vinyl alcohol copolymer, polyvinyl alcohol, polyvinyl chloride, and 6-nylon. The multilayer molded article according to claim 1, wherein the molded article is a multilayer molded article. 4. The tensile strength of the moisture barrier layer is 20 to 200.
The multilayer molded body according to any one of claims 1 to 3, which is MPa. 5. The adhesive strength between the substrate layer and the moisture barrier layer is 5 to 70.
The multilayer molded article according to any one of claims 1 to 4, wherein the thickness is N / 15 mm. 6. The multilayer molded article according to claim 1, wherein a moisture barrier layer is laminated on both sides of the base material layer using an adhesive. 7. The adhesive strength between the substrate layer and the moisture barrier layer is 10 to 3
The multilayer molded body according to claim 6, wherein the thickness is 0 N / 15 mm.