JPH11198304A - Thermoforming multilayer structure and thermoformed vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the gas barrier properties under highly humid conditions, steam barrier properties, melt formability and transparency of a structure by a structure wherein a layer made of a gas barrier resin including a specified amount of a constitutional repeating unit representing by a specified constitutional formula and a layer made of thermoplastic resin excluding the above- mentioned resin are provided. SOLUTION: This thermoforming multilayer structure has a layer made of a gas barrier resin including 30 mol.% or more of a constitutional repeating unit represented by a formula, in which R<1> represents a 1-2C alkyl group and R<2> represents a hydrogen atom or a 1-3C alkyl group, and a layer made of a thermoplastic resin excluding the above-mentioned resin. Further, as the thermoplastic resin, a polyolefin, a polystyrene or a polyamide is employed. Furthermore, a layer made of a bonding resin may well be provided between the layer made of the gas barrier resin and the layer made of the thermoplastic resin. In this case, as the bonding resin, a polyolefin modified by an unsaturated carboxylic acid or by its anhydride is employed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer structure for thermoforming, which is excellent in gas barrier properties, in particular, gas barrier properties under high humidity, and is also excellent in water vapor barrier properties, melt moldability, and transparency. The present invention relates to a thermoformed container formed by molding.

[0002]

2. Description of the Related Art At present, gas barrier resins made of a resin having particularly excellent performance of blocking gas such as oxygen (gas barrier properties) are widely used mainly in the field of packaging materials containing foods and pharmaceuticals. I have. There are various forms of packaging containers using such a gas barrier resin, and among them, containers obtained by thermoforming a multilayer body having a gas barrier resin layer are widely used, and even as a thin film-shaped one or relatively. It is also used as a thick sheet. As a resin material having particularly excellent gas barrier properties, ethylene-vinyl alcohol copolymer (hereinafter referred to as EVO)
H), vinyl alcohol-based polymers, vinylidene chloride-based polymers (hereinafter sometimes abbreviated as PVDC), acrylonitrile-based polymers (hereinafter sometimes abbreviated as PAN), and the like. Are known.

[0003] EVOH has high gas barrier properties under low humidity, and can be melt-molded, especially co-extruded with polyolefin or the like. However, there is a drawback that the gas barrier property is deteriorated under high humidity, so that there is a limitation in use and use form. For example, EVOH is often used as the innermost layer in fields where fragrance retention is important, such as juice containers.
Since the barrier property under high humidity is insufficient, it is necessary to use the EVOH layer also for the intermediate layer, which increases the cost. In addition, it has a disadvantage of lacking water vapor barrier properties, and therefore, in many applications, it has to be used as a multilayer body with a material having relatively good water vapor barrier properties, such as polyolefin such as polypropylene and polyethylene. When higher water vapor barrier properties are required, it may be difficult to use.

[0004] Unlike EVOH, PVDC has a small humidity dependence of gas barrier properties, so that it exhibits high gas barrier properties even under high humidity and has good water vapor barrier properties. But,
Since the thermal stability is very poor, it is necessary to copolymerize with vinyl chloride or the like or to add a plasticizer in order to perform melt molding. However, such a melt-moldable PVDC copolymer is generally inferior to EVOH in gas barrier properties. Therefore, in fields where high gas barrier properties are required, PVDC in which the copolymerization or addition of a plasticizer is refrained may be carried out by an emulsion coating method or the like. It is used after being coated on a film or the like by a solution coating method. However, since the thickness of the barrier layer is limited by these methods, it is difficult to adapt to a field where high gas barrier properties are required.

[0005] Although PAN homopolymer has excellent gas barrier properties, it has a very high melting point, and is difficult to melt-mold. Melt-moldable copolymers are generally EVOH
Inferior to gas barrier properties.

Also, EVOH, PVDC and PAN
All have a problem that when the thickness is increased, the transparency is deteriorated and the film becomes cloudy. In addition, PVDC and PAN have a problem that they are colored yellow by light or heat during melt molding. It is known that these problems can be alleviated by copolymerization, but the gas barrier properties are also worsened, so the gas barrier properties are excellent even under high humidity, and also excellent in melt moldability. The development of resins has been long awaited and is up to today.

On the other hand, polymers comprising allyl alcohols represented by polyallyl alcohol, polymethallyl alcohol and the like as recurring structural units are known, and are disclosed in US Pat. Nos. 2,455,722, 2,467,105 and 3,673.
Nos. 285897 and 3666740 (Japanese Patent Publication No. 47-4)
0308), No. 4,125,694, British Patent No. 8542
No. 07 has been filed for a polymerization method.

Some of the applications relating to these polymerization methods include:
Although the use of the allyl alcohol-based polymer is also described, there is no description that such a polymer has an extremely good gas barrier property. For example, U.S. Pat. No. 4,125,694 describes "coating agents, adhesives, anti-smearing agents, molding powders, paints, lacquers, laminates, fillers, dispersants, resin product intermediates (coatin).
g agents, adhesives, impregnants, molding powders,
paints, varnishes, laminates, fillers, in dispers
ions, and as intermediate in resin production) "
However, there is no description of applications requiring a high degree of gas barrier properties, particularly use of thermoformed containers. Further, among the allyl alcohol-based polymers, polyallyl alcohol, which is the most typical polymer, does not achieve the object of the present invention, and R ¹ in the formula (1) in the claims of the present application is not a hydrogen atom but a specific alkyl group. There is no description or suggestion that the object of the present invention is achieved only when.

Also, Japanese Patent Application Laid-Open No. Hei 8-5080065 (W)
O95 / 12624) describes the use of a polymer having a vinyl alcohol-based or allyl alcohol-based monomer as a structural unit as a packaging material having an oxygen permeability at a high humidity of a specific value or less. However, as the allyl alcohol-based polymer, it is an essential requirement that R ¹ in the formula (1) in the present application be a hydrogen atom, and R ¹ is not a hydrogen atom but a specific alkyl group. Is not described at all. Further, it is said that it is more preferable to use a vinyl alcohol unit in place of the allyl alcohol unit. In Examples, a part of the hydroxyl group of EVOH is acylated with an aromatic carboxylic acid, so that it can be used under high humidity. Only the example of improving the oxygen barrier property of the present invention is described, and the means for solving the problem is completely different from the present invention.

[0010] Further, Polymer Bulletin, 3 (10), pp 5
In literatures such as 21-528 and 1980, there is a description of polymethallyl alcohol whose steric structure is regulated to isotactic or syndiotactic, but there is no description or suggestion of gas barrier properties.

[0011]

As described above, among the conventional gas barrier resins, EVOH is excellent in that it can achieve both gas barrier properties and melt moldability. However, by further improving the gas barrier properties, EVOH is used. It is desired to reduce the cost and the effect of thickness unevenness by reducing the thickness of the gas barrier layer. There is also a demand for expanding the range of use and the form of use by improving the gas barrier properties and water vapor barrier properties under high humidity. It is an object of the present invention to provide a gas barrier resin excellent in gas barrier properties, water vapor barrier properties, melt moldability and transparency under high humidity, and a multilayer structure including a layer made of the resin.

[0012]

An object of the present invention is to provide a gas barrier resin containing a repeating structural unit represented by the following formula (1) in an amount of 30 mol% or more and a layer made of a thermoplastic resin other than the above. This is achieved by providing a thermoformed multilayer structure.

[0013]

Embedded image

(In the formula, R ¹ represents an alkyl group having 1 to ² carbon atoms, and R ² represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

At this time, it is preferable that the thermoplastic resin is polyolefin, polystyrene or polyamide. It is also preferable to have a layer made of an adhesive resin between a layer made of a gas barrier resin and a layer made of a thermoplastic resin, and the adhesive resin is a polyolefin modified with an unsaturated carboxylic acid or an anhydride thereof. Is more preferable. Further, a thermoformed container obtained by thermoforming the multilayer structure for thermoforming is also a preferred embodiment of the present invention.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The gas barrier resin of the present invention contains 30 mol% of a repeating structural unit represented by the following formula (1).
It is made of a resin containing the above.

[0017]

Embedded image

(In the formula, R ¹ represents an alkyl group having 1 to ² carbon atoms, and R ² represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

R ¹ represents a substituent selected from a methyl group and an ethyl group. Of these, a methyl group is most preferable from the viewpoint of gas barrier properties. R ² represents a hydrogen atom, a substituent selected from a methyl group, an ethyl group, a propyl group, and an isopropyl group, and among these, a hydrogen atom is optimal from the viewpoint of gas barrier properties. When the carbon number of these substituents exceeds the above value, the glass transition point decreases, the gas barrier property decreases, and the stiffness decreases.

The content of the above structural units in the resin must be 30 mol% or more, and is more preferably in the range of 45 to 100 mol%. More preferably, it is 70 to 100 mol%, and the range of 80 to 100 mol% is optimal. If the content of the structural unit is below the above range, the gas barrier properties will be poor. Further, two or more kinds of the above structural units having different R ¹ and / or R ² may be contained. In this case, the content of the structural unit in the resin is the total thereof.

The copolymer components other than the above structural units include:
There is no particular limitation as long as the performance is not adversely affected.
Specific examples of the copolymer component include ethylene, propylene,
Olefins such as 1-butene, isobutene, 1-pentene, 1-hexene, 1-octene, diene monomers such as butadiene and isoprene, and aromatic-substituted vinyl monomers such as styrene and α-methylstyrene. Monomers, methyl acrylate, ethyl acrylate, butyl acrylate, acrylic monomers such as methyl methacrylate, methyl vinyl ether, ethyl vinyl ether, vinyl ether monomers such as butyl vinyl ether, vinyl chloride,
Vinyl halide monomers such as vinyl fluoride, vinylidene chloride, vinylidene halide monomers such as vinylidene fluoride, acrylonitrile, acrylonitrile monomers such as methacrylonitrile, maleimide, N-methylmaleimide, Maleic acid derivative monomers such as dimethyl maleate;

When a copolymer component is contained, the copolymerization method may be either random copolymerization or alternate copolymerization. However, when the copolymer component is large (the copolymer component is about 30%).
Mol% or more) preferably has high alternating copolymerizability from the viewpoint of gas barrier properties. When the alternating copolymerizability is high, the content of the structural unit represented by the formula (1) is 45 to 60 mol%.
Is preferable.

The stereoregularity of the resin is not particularly limited, but is preferably regulated by syndiotactic or isotactic, since the gas barrier property is further improved. In this case, it is preferable that the content be controlled to be syndiotactic or isotactic in a triad display of 60 mol% or more. More preferably, it is preferably regulated to 80 mol% or more. However, in general, it is not easy to manufacture a resin with restricted stereoregularity or the cost is increased. Therefore, it is preferable to use a resin different from an atactic resin depending on the application.

The intrinsic viscosity of the resin used in the gas barrier resin of the present invention is preferably in the range of 0.1 to 3 dl / g, and preferably 0.2 to 2 dl / g, as measured in metacresol at 30 ° C. Is more preferable, and 0.3
Most preferably, the range is from dl / g to 1.5 dl / g. If the intrinsic viscosity is too low, sufficient strength cannot be obtained. On the other hand, if the intrinsic viscosity is too large, melt molding becomes difficult, and only film formation by a solution coating method can be performed.

As a method for adjusting the intrinsic viscosity of the resin used for the gas barrier resin to the above range, in addition to a method for adjusting the degree of polymerization of the resin, a vinylmethoxysilane described in JP-A-60-144304 and the like can be used. And the like, for example, a method of copolymerizing a silicon-containing olefinically unsaturated monomer such as described above.

The rigidity and tensile strength of the resin used in the gas barrier resin of the present invention is preferably set at 45 to 95 ° C., preferably 50 to 90 ° C., and more preferably 55 to 85 ° C. when the resin is absolutely dried. It is preferable in improving the mechanical performance such as. When the glass transition point is lower than the above range, the rigidity and the like are poor, and when the glass transition point is higher than the above range, the drop strength, impact resistance and the like are poor.

The glass transition point of the resin used for the gas barrier resin when the condition is adjusted at 20 ° C. and 85% RH may be set to 20 ° C. or higher, preferably 25 ° C. or higher, more preferably 30 ° C. or higher. It is preferable for improving gas barrier properties under high humidity.

The gas barrier resin 2 used in the present invention
It is possible to set the saturated moisture absorption at 0 ° C. and 65% RH to 0.5 to 15% by weight, preferably 1.0 to 10% by weight, and more preferably 1.5 to 6% by weight. Good for improving sex. When the saturated moisture absorption is below the above range, the drop strength and impact resistance are poor, and when the saturated moisture absorption exceeds the above range, the rigidity and gas barrier properties are poor.

As a method of adjusting the glass transition point and / or the saturated moisture absorption of the resin used as the gas barrier resin to the above-mentioned range, a method of appropriately selecting R ¹ and R ² of the resin, and a method of adjusting the stereoregularity of the resin Examples of the method include a method of performing copolymerization, a method of copolymerizing with a copolymerizable comonomer, and a method of adjusting random copolymerizability / alternate copolymerizability in the case of copolymerization. By appropriately combining these, the glass transition point can be easily adjusted.

The oxygen permeability of the gas barrier resin of the present invention at 20 ° C. and 100% relative humidity is 30 ml · 20 μm.
m / m ² · day · atm or less,
More preferably, 20 ml · 20 μm / m ² · day · a
tm or less, more preferably 10 ml · 20 μm
/ M ² · day · atm or less, optimally 5 ml ·
It is 20 μm / m ² · day · atm or less. 30ml
・ When it is larger than 20 μm / m ²・ day ・ atm,
In some cases, it cannot be used in applications used under high humidity.

The gas barrier resin of the present invention has
Oxygen permeability at 10 ° C. and 65% relative humidity is 10 ml · 2
Preferably 0 .mu.m / m is ² · day · atm or less, more preferably ^{5ml · 20μm / m 2 · day} ·
atm or less, more preferably 2 ml · 20 μm
/ M ² · day · atm or less, optimally 1 ml ·
It is 20 μm / m ² · day · atm or less.

Further, 40% of the gas barrier resin of the present invention
Permeability at 30 ° C and relative humidity 90% is 30g ・ 30μm
/ M ² · day or less, more preferably 20 g · 30 μm / m ² · day or less, and even more preferably 10 g · 30 μm / m ² · day or less. When it is larger than 30 g · 30 μm / m ² · day, it may be necessary to laminate and use a layer made of a resin having low moisture permeability represented by polyolefin or the like depending on the use.

The adjustment of the oxygen permeability or the moisture permeability as described above includes a method of appropriately selecting R ¹ and R ² in the formula (1) of the resin constituting the gas barrier resin, a method of adjusting the stereoregularity, Examples of the method include a method of performing copolymerization and a method of stretching and orienting the resin constituting the gas barrier resin.

The method for producing the resin used for the gas barrier resin of the present invention is not particularly limited.
Various methods can be adopted, including the methods described in the prior art. The main methods include the following production methods. First production method: produced by polymerizing a monomer represented by the following formula (2) and then reducing it.

[0035]

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(Wherein R ¹ is a methyl group or an ethyl group,
X represents an alkoxyl group, a hydroxyl group, a halogen atom, a hydrogen atom, a methyl group, an ethyl group, a propyl group or an isopropyl group, respectively. )

Specific examples of the above monomers include acrylic acid derivatives such as methacrylic acid and 2-ethylacrylic acid; acrylic acid ester derivatives such as methyl methacrylate and methyl 2-ethylacrylate; methacrolein; Acrolein derivatives such as ethyl acrolein; vinyl ketone derivatives such as isopropenyl methyl ketone, isopropenyl ethyl ketone, isopropenyl propyl ketone, and isopropenyl isopropyl ketone.

The above monomers can be polymerized by known polymerization methods such as radical polymerization and anion polymerization. Examples of the radical polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4′-dimethylvaleronitrile), and 2,2′-azobis (4-methoxy-
Azo-based initiators such as 2,4'-dimethylvaleronitrile); and peroxide-based initiators such as isobutyl peroxide, di-n-propylperoxydicarbonate, and t-butylperoxypivalate. The polymerization temperature at this time is not particularly limited, and the polymerization is usually performed in a temperature range from room temperature to about 100 ° C. As the conditions for the anionic polymerization,
As an initiator, a basic alkali metal or alkaline earth metal derivative such as butyllithium, lithium aluminum hydride, methylmagnesium bromide, ethylmagnesium chloride, and triphenylmethylcalcium chloride is used as an initiator, and usually tetrahydrofuran, dimethoxyethane The polymerization is carried out at a low temperature of about -100 ° C. to room temperature using an aprotic solvent such as diethyl ether or the like as a solvent. Further, by appropriately selecting the above polymerization conditions, a polymer whose steric structure is restricted to isotactic or syndiotactic can be obtained. For example, when polymerization of methyl methacrylate is performed using triphenylmethyl calcium chloride, bis (pentamethylcyclopentadienyl) samarium methyl, or the like as an initiator, syndiotactically regulated polymethyl methacrylate is obtained, and hydrogen When methyl methacrylate is polymerized by using lithium aluminum chloride as an initiator, polymethyl methacrylate regulated in an isotactic manner is obtained.

As a method for reducing the obtained polymer, a method using a metal hydride such as lithium aluminum hydride, sodium borohydride, lithium borohydride, diborane or the like as a reducing agent, ruthenium-based, rhodium-based, nickel-based , Palladium-based and platinum-based transition metal catalysts. The reduction reaction solvent is appropriately selected in consideration of the solubility of the polymer and the reactivity with the reducing agent. Examples include tetrahydrofuran,
N-methylmorpholine, dimethylacetamide, dimethylformamide, dimethylsulfoxide, dimethoxyethane, methanol, ethanol, propanol and the like. The reduction reaction temperature is usually selected from the range of room temperature to 200 ° C, and the range of 50 ° C to 150 ° C is preferable.
In the case where a polymer whose steric structure is controlled to be isotactic or syndiotactic is reduced, a reduced polymer having a controlled steric structure is obtained.

Second production method: produced by polymerization of an allyl alcohol having a structure represented by the following formula (3).

[0041]

Embedded image

(In the formula, R ¹ represents an alkyl group having 1 to ² carbon atoms, and R ² represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

The method for polymerizing the above allyl alcohols is not particularly limited. For example, US Pat.
7, 3666740 (JP-B-47-40308) and British Patent 854207.

Third production method: It is obtained by chemically converting a halogen atom into a hydroxyl group after polymerization of an allyl halide derivative having a structure represented by the following formula (4).

[0045]

Embedded image

(Wherein, R ¹ is an alkyl group having 1 to 2 carbon atoms, R ² is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms,
X represents a halogen atom. )

The third production method is described, for example, in US Pat. No. 4,125,694.

The gas barrier resin of the present invention may be blended with another thermoplastic resin as long as the effect is not impaired. Examples of such thermoplastic resins include polyolefins such as polyethylene, polypropylene, polybutene and polymethylpentene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycaprolactam (6-nylon), and polylauryl lactam (12- Nylon), polyamides such as polyhexamethylene adipamide (6,6-nylon), polystyrene, polyvinyl chloride, polycarbonate, polymethyl methacrylate, polyurethane and the like. The amount of the resin to be blended is usually in the range of 50% by weight or less.

Further, the gas barrier resin of the present invention may contain various additives as necessary. Examples of such additives include antioxidants, plasticizers, heat stabilizers, ultraviolet absorbers, antistatic agents, lubricants, colorants, fillers, or other high molecular compounds, and Blends can be blended as long as the effects of the present invention are not impaired. Specific examples of the additives include the following.

Antioxidants: 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4'-thiobis- (6-t-butylphenol), 2,2 '-Methylene-bis- (4-methyl-6-
t-butylphenol), octadecyl-3- (3 ′,
5'-di-t-butyl-4'-hydroxyphenyl) propionate, 4,4'-thiobis- (6-t-butylphenol) and the like.

UV absorber: ethylene-2-cyano-
3,3′-diphenyl acrylate, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole,
2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5 '-Methylphenyl) 5-
Chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone and the like.

Plasticizers: dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, phosphate ester and the like. Antistatic agents: pentaerythritol monostearate, sorbitan monopalmitate, sulfated polyolefins,
Polyethylene oxide, carbowax, etc. Lubricants: ethylene bis stearoylamide, butyl stearate, metal salts of higher fatty acids, and the like. Colorants: carbon black, phthalocyanine, quinacridone, indoline, azo pigments, red iron, etc. Filler: glass fiber, asbestos, ballastonite, calcium silicate, mica, titanium oxide, calcium carbonate, silicon oxide, etc.

The multilayer structure for thermoforming of the present invention has a layer made of the above gas barrier resin and a layer made of other thermoplastic resin.

The term "thermoforming" as used in the present invention means that a film or sheet is heated and softened and then formed into a mold. As a forming method, a method of forming into a mold shape using a vacuum or a pressurized air and further using a plug as necessary (straight method, drape method, air slip method, snapback method, plug assist method, etc.) or press forming is used. And the like. Various molding conditions such as the molding temperature, the degree of vacuum, the pressure of the compressed air or the molding speed are appropriately set depending on the shape of the plug, the shape of the mold, the properties of the raw material film or sheet, and the like.

The molding temperature is not particularly limited.
It is sufficient that the temperature is sufficient to soften the resin for molding, but the suitable temperature range varies depending on the raw material film or sheet. For example, when thermoforming a film, the film is not heated to a temperature high enough to cause melting of the film due to heating or to transfer irregularities on the metal surface of the heater plate to the film, but to a temperature low enough for insufficient shaping. Preferably, the film temperature is 50 to 120 ° C, preferably 60 to 110 ° C, more preferably 70 to 100 ° C. On the other hand, when thermoforming a sheet having a thickness greater than that of a film, molding may be possible even at a higher temperature than in the case of a film, and molding is performed in a temperature range of 130 to 180 ° C.

The thermoformed container of the present invention is a three-dimensionally thermoformed container in which a concave portion is formed in the plane of a film or sheet. The shape of the concave portion is determined according to the shape of the contents and the like.

In the multi-layer structure for thermoforming of the present invention, the thermoplastic resin laminated with the gas barrier resin is not particularly limited. However, one or both surfaces of the gas barrier resin may be polyolefin, polyamide, polyester, polycarbonate, polystyrene, or polyolefin. It is preferable to laminate a layer made of at least one thermoplastic resin selected from the group consisting of vinyl chloride and polyurethane.

As the polyolefin, polyethylene,
Polypropylene, polybutene, polymethylpentene, ethylene-propylene copolymer, etc .;
Polycaprolactam (6-nylon), polylauryl lactam (12-nylon), polyhexamethylene adipamide (6,6-nylon), etc .;
Polyethylene terephthalate, polybutylene terephthalate, etc .;
S), high-impact polystyrene (HIPS), styrene-butadiene copolymer (SB), styrene-butadiene-acrylonitrile copolymer (ABS), and the like, respectively.

Among these, it is preferable to laminate polyolefin, polystyrene or polyamide.

The polyolefin is not particularly limited, but may be a high-density or low-density polyethylene,
Homopolymers such as polypropylene and polybutene-1, and copolymers or α-olefins of α-olefins selected from ethylene, propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc. -Copolymers of olefins with other copolymer components. As copolymerization components other than these α-olefins,
Diolefin, N-vinyl carbazole, vinyl chloride,
Vinyl compounds such as vinylidene chloride, vinyl acetate, styrene, acrylonitrile, and vinyl ether; unsaturated carboxylic acids such as maleic acid, acrylic acid, methacrylic acid, ethacrylic acid, fumaric acid, and itaconic acid; esters and acid anhydrides thereof; To which a hydroxyl group or an epoxy group is added. For example, various copolymers such as a copolymer of a graftable monomer and a polyolefin, and an ionomer resin which is a reaction product of an α-olefin / α, β-unsaturated carboxylic acid copolymer and an ionic metal compound. It can also be used.
Among them, polypropylene and polyethylene are particularly preferred. Especially polypropylene, when used as a relatively thick sheet-shaped thermoformed container, moldability,
It is suitable from the viewpoints of economy, shape retention and the like. These polyolefin resins can be used alone or in combination of two or more. Such a polyolefin is preferably laminated because it has good moldability and heat sealability, is economical, and has excellent moisture-proof properties.

As the polystyrene, not only a homopolymer of styrene but also a copolymer obtained by copolymerizing a small amount of a monomer component other than styrene or a blend obtained by blending a small amount of a resin obtained by polymerizing a monomer other than styrene. And the styrene component may be 80% by weight or more. Therefore,
The polystyrene of the present invention also includes so-called HIPS (high impact polystyrene) containing a small amount of a rubber component. Since such polystyrene has high rigidity, it can be kept in a thin shape. Further, since it has excellent gloss, it is possible to obtain a molded article having an excellent appearance regardless of whether it is transparent or opaque. Furthermore, a homopolymer of styrene is excellent in transparency, and a container using the same is excellent in visibility of contents.

Further, the polyamide resin is not particularly limited. For example, polycaproamide (nylon-
6), polyundecaneamide (nylon-11), polylauryl lactam (nylon-12), polyhexamethylene adipamide (nylon-6,6), polyhexamethylene sebacamide (nylon-6,12) Homopolymer, caprolactam / lauryl lactam copolymer (nylon-6 / 12), caprolactam / aminoundecanoic acid copolymer (nylon-6 / 11), caprolactam /
ω-aminononanoic acid copolymer (nylon-6 / 9), caprolactam / hexamethylenediammonium adipate copolymer (nylon-6 / 6,6), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate Polymer (nylon-
And copolymers such as 6/6, 6/6, and 12). These polyamide resins can be used alone or in combination of two or more. Such a polyamide resin is preferable in that the moldability becomes good when a thermoformed container having a relatively small thickness is formed. In such a container, it is preferable to further include a heat seal layer in addition to the polyamide resin layer from the viewpoint that the contents can be easily sealed, and a thermoforming multilayer film having both a heat seal layer and a polyamide resin layer is preferable. It is an embodiment.

The layer structure of the multilayer structure for thermoforming of the present invention is as follows:
Although there is no particular limitation other than having a layer made of a gas barrier resin and a layer made of other thermoplastic resin, a configuration having an adhesive resin layer between the gas barrier resin layer and the thermoplastic resin layer is preferred. Preferred are given.

The resin used for the adhesive resin layer is not particularly limited, but may be a polyurethane-based or polyester-based one-pack or two-pack curable adhesive, an unsaturated carboxylic acid or an anhydride thereof (anhydrous anhydride). Those obtained by copolymerizing or graft-modifying maleic acid, etc.) to an olefin polymer or copolymer (carboxylic acid-modified polyolefin resin)
Is preferably used. By providing such an adhesive resin layer, a thermoformed container having excellent interlayer adhesion can be obtained.

Among these, it is more preferable that the adhesive resin is a carboxylic acid-modified polyolefin resin from the viewpoint of adhesiveness with the gas barrier resin layer or the thermoplastic resin layer or compatibility at the time of scrap recovery. Examples of such a carboxylic acid-modified polyethylene resin include polyethylene {low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE)}, polypropylene, copolymerized polypropylene, ethylene-vinyl acetate. Copolymer, ethylene-
Carboxylic acid-modified (meth) acrylic ester (methyl ester or ethyl ester) copolymers and the like can be mentioned.

The structure of the multilayer structure for thermoforming of the present invention is not particularly limited. If necessary, an adhesive resin layer may be introduced between the gas barrier resin layer and another thermoplastic resin layer. Further, a collecting layer (regrind layer) for collecting burrs and ears at the time of molding or defective molding products may be provided. As a specific example of the layer configuration, the gas barrier resin of the present invention is BAR, the other resin is A or B, and the adhesive layer is A.
D, when the collection layer is represented by REG, A / BAR, A / AD /
BAR, A / BAR / A, A / BAR / B, A / AD /
BAR / B, A / AD / BAR / AD / A, A / AD /
BAR / AD / B, A / REG / AD / BAR / AD /
REG / A, A / AD / BAR / AD / BAR / AD /
A and the like, but are not limited thereto.

Among the above-mentioned multilayer structures, a structure in which a layer made of another thermoplastic resin is provided on both sides of a layer made of a gas barrier resin is preferable. In this case, a structure having an adhesive layer between both resin layers is more preferable. preferable.

The thickness of the allyl alcohol-based polymer resin layer used in the present invention is preferably set in the range of 0.1 to 50 μm. More preferably 0.2 to 40μ
m, more preferably 0.5 to 30 μm, and most preferably 1 to 25 μm. When it is below the above range, sufficient gas barrier properties cannot be obtained, and when it exceeds the above range, the drop strength and impact resistance are poor. Also,
The overall thickness of the multilayer structure for thermoforming is not particularly limited, and may be a thin film or a thick sheet. Specifically, the thickness is, for example, about 50 to 3000 μm, preferably 80 to 2000 μm, more preferably 100 to 1500 μm.

The temperature of the multilayer structure at 20 ° C. and the relative humidity of 65
% Is 30 ml / m ² · day · a
tm or less, more preferably 10 m
1 / m ² · day · atm or less, more preferably 5 ml
/ M ² · day · atm or less, optimally 1 ml / m ² · d
ay · atm or less. When the oxygen permeation amount at 20 ° C. and a relative humidity of 65% is larger than the above-mentioned values, it may not be able to withstand use for applications requiring high gas barrier properties.

In addition, the multilayer structure was set at 20 ° C. and a relative humidity of 10 ° C.
The oxygen permeation amount at 0% RH is 50 ml / m ² · da
It is preferably at most y · atm, more preferably at most 30 ml / m ² · day · atm, even more preferably at most 20 ml / m ² · day · atm.
More preferably to below ^{0ml / m 2 · day · atm} , and most preferably less ^{1ml / m 2 · day · atm} . When the amount of oxygen permeation at 20 ° C. and 100% RH is larger than the above values, it becomes difficult to use the composition in applications requiring high gas barrier properties under high humidity.

The adjustment of the amount of oxygen permeation or moisture permeability as described above can be performed by appropriately selecting R ¹ and R ² in the formula (1) of the resin constituting the gas barrier resin, adjusting the stereoregularity, Examples of the method include a method of performing copolymerization, a method of adjusting the thickness of a layer made of the gas barrier resin, and a method of stretching and orienting the resin constituting the gas barrier resin.

The method for forming a multilayer of the gas barrier resin of the present invention and another resin is not particularly limited, but typical methods include coextrusion molding, lamination, extrusion coating, and solution coating. And the like.

Examples of the resin to be combined with the gas barrier resin layer in the case of forming a multilayer by coextrusion molding include the above-mentioned thermoplastic resins. Among the above resins, the gas barrier resin of the present invention such as polyolefins is used. In the case of forming a multilayer with a resin having poor compatibility with water, it is usually preferable to use a polyolefin modified with a reactive or polar functional group such as maleic anhydride or acrylic acid as the adhesive resin. In the case of forming a multilayer with a resin having relatively good compatibility with the gas barrier resin of the present invention, such as polyester, polyamide, and polycarbonate, an adhesive resin is not necessarily required. The molding temperature is usually 150 to
A range of 300 ° C. is preferred.

In the case of multi-layering by a solution coating method, after dissolving the gas barrier resin of the present invention in a solvent, a film, sheet or the like of another resin is coated. Specific examples of the above solvent include methanol, ethanol, 1-propanol, 2
Lower alcohol solvents such as -propanol and 2-methoxymethylethanol; aprotic polar solvents such as dimethylformamide, dimethylacetamide and dimethylsulfoxide; In the case of solution coating on a poorly compatible resin such as polyolefins, it is preferable to coat an anchor coating agent beforehand or to perform a solution coating after corona-treating the surface, such as polyester, polyamide, and polycarbonate. When performing a solution coating on a resin having relatively good compatibility, the solution coating may be performed directly, or the solution coating may be performed after performing a corona treatment or an anchor coating treatment.

Various types of thermoformed containers formed from the above-described multilayer structure are used for various purposes. Among them, the superiority of using the resin composition of the present invention, which is excellent in gas barrier properties, is exerted greatly when used as various packaging containers. It is particularly suitable as a packaging container for foods, pharmaceuticals, agricultural chemicals and the like, whose quality is likely to deteriorate due to the presence of oxygen, such as pudding, jelly and miso cups.

[0076]

The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the invention thereto. In the following synthesis examples and comparative examples, unless otherwise specified, the ratio means the weight ratio, and “%” means “% by weight”. The measuring method and the evaluation method are as follows.

(1) Intrinsic viscosity The m-cresol solution was measured at 30 ° C. using an Ostwald viscometer.

(2) Glass Transition Point and Melting Point The glass transition point and melting point are measured by a differential scanning calorimeter (DSC) RDC220 / SSC5200 manufactured by Seiko Instruments Inc.
The measurement was performed based on JIS K7121 using the H type.
However, indium and lead were used for temperature calibration. In addition, the glass transition point at the time of absolute drying referred to in the present invention is determined according to the JIS standard
After the temperature was once raised to 200 ° C. by the method described, the temperature was lowered at a cooling rate of 30 ° C./min to a temperature about 50 ° C. lower than the glass transition point, and the temperature was raised again at a rate of 10 ° C./min. The measured value (2nd. Run) refers to the glass transition point at the time of conditioning at 20 ° C. and 85% RH. The sample was sealed in a sealing pan immediately after sufficient conditioning, and the temperature was raised at a rate of 10 ° C. / Min (1st. Ru)
n). Further, the glass transition point referred to in the present invention is the above-mentioned J
The midpoint glass transition temperature (Tmg) referred to in IS, and the melting point referred to in the present invention refers to the melting peak temperature (Tpm) referred to in JIS.

(3) Saturated moisture absorption A film made of a gas barrier resin is dried at 80 ° C. in a drier.
Then, from the weight (X) when sufficiently dried until reaching a constant weight and the weight (Y) when sufficiently adjusted at 20 ° C. and 65% RH, the formula {(Y−X) / Y} × 100 (%) I asked for it. In the case of a multilayer film including a gas barrier layer, the saturation moisture absorption of the gas barrier layer can be determined in the same manner. However, when the thermoplastic resin constituting the laminated film is hygroscopic, the saturated moisture absorption of the gas barrier layer alone can be obtained by calculating the saturated moisture absorption of the thermoplastic resin separately.

(4) Oxygen permeation amount MODERN CONTROLS INC. It measured according to the method of JIS K7126 (isobaric method) under the conditions of 20 ° C., 65% RH and 20 ° C., 100% RH using an oxygen transmission amount measuring apparatus MOCONOX-TRAN 2/20. In addition, the oxygen permeability referred to in the present invention is the oxygen permeability measured at an arbitrary film thickness (unit: ml / m ² · da) when a film composed of a single layer is measured.
y · atm) is converted to the amount of oxygen permeation at a film thickness of 20 μm (oxygen permeability; ml · 20 μm / m ² · day · a
tm). Further, when the multilayer structure for thermoforming was measured, the value without such conversion, that is, the oxygen permeation amount (ml / m ² · day · atm) was shown as it is.
Further, when measured in the form of a thermoformed container, the container 1
Oxygen permeation amount per unit (ml / container · d
ay.atm).

(5) Moisture Permeability When measured on a single layer film,
It was measured according to the description of JIS Z0208 under the conditions of 40 ° C. and 90% RH, and the film thickness was converted to a value of 30 μm (g · g).
30 μm / m ² · day) was calculated. In the case where the multilayer structure for thermoforming was measured, the value was not converted (g / m ² · day).

(6) Haze value A part of the sample film was cut out, silicone oil was applied, and JIS HR-100 manufactured by Murakami Color Research Laboratory was used.
The haze value was measured according to K7105.

Synthesis Example 1 Atactic polymethallyl alcohol (a-PMA)
Synthesis of AL) Lithium aluminum hydride 25 in a reaction vessel with a cooler
After charging 0 parts by weight, replacing with nitrogen and adding 3000 parts of N-methylmorpholine, the mixture was heated to 130 ° C. and refluxed. Atactic polymethyl methacrylate 6
A solution consisting of 00 parts by weight and 6000 parts of N-methylmorpholine was added, and the mixture was refluxed for 4 hours after completion of the dropwise addition. Thereafter, 1000 parts by weight of ethyl acetate are added dropwise to inactivate unreacted hydrides, and a 50% aqueous solution of phosphoric acid 5000
Parts by weight were added dropwise. After cooling, the mixture was separated into a supernatant and a solid by centrifugation. The obtained supernatant was added to distilled water to precipitate a polymer (No. 1). In addition, 10000 parts of ethanol was added to the obtained solid content, and the mixture was heated and dissolved at 60 ° C. for 1 hour, filtered through a glass filter, and the obtained filtrate was concentrated by an evaporator. 2) was precipitated. The polymer obtained by precipitation (No. 1 and No. 2) was put together at 100 ° C.
After sufficiently washing by boiling with distilled water, vacuum drying was performed to obtain 380 parts by weight of a-PMAAL.

The intrinsic viscosity of the obtained a-PMAAL in m-cresol at 30 ° C. was 0.77 dl / g.
The vacuum-dried polymethallyl alcohol was measured by a scanning differential thermal analyzer (DSC) at a heating rate of 10 ° C./min after being melted and quenched in a nitrogen stream, and the glass transition temperature was 75 ° C. And no crystal melting peak was present. In addition, the glass transition temperature when conditioning at 20 ° C. and 85% RH was 49 ° C. a-PMAAL
Are shown in Table 1.

The thus-obtained a-PMAAL was melt-extruded at 220 ° C. into pellets by a Labo Plastomill manufactured by Toyo Seiki equipped with a twin screw extruder having a screw diameter of 20 mm. Using the obtained pellet, the screw diameter is 20
a-PMAAL having a thickness of 20 μm by forming a single-layer film at a die temperature of 220 ° C. by using a laboratory plastomill manufactured by Toyo Seiki equipped with a uniaxial extruder having a width of 300 mm and a coat hanger die having a width of 300 mm and a lip gap of 0.3 mm. A film was obtained. The resulting film was colorless and transparent, and had a good appearance. Table 1 shows the physical property values of a-PMAAL and the measurement results of the moisture absorption, oxygen permeability, moisture permeability, and haze value of the obtained film.

Synthesis Example 2 Syndiotactic polymethallyl alcohol (s-
Synthesis of PMAAL) Bis (pentamethylcyclopentadienyl) samarium methyl was used as an initiator instead of the atactic polymethyl methacrylate used in Synthesis Example 1, and 0 ° C. in toluene
An s-PMAAL was obtained in the same manner as in Synthesis Example 1 except that syndiotactic polymethyl methacrylate (having a tacticity of 80% in triad display) obtained by polymerization was used. Obtained s-PMAA
The tacticity of L was analyzed by ¹³ C-NMR measurement in heavy DMSO, and the syndiotacticity was 80% in triad. Using the obtained resin, a film was obtained and evaluated in the same manner as in Synthesis Example 1.
Table 1 shows the physical property values of s-PMAAL and the measurement results of the moisture absorption, oxygen permeability, moisture permeability, and haze value of the obtained film.

Synthesis Example 3 Isotactic polymethallyl alcohol (IP
Synthesis of MAAL) Isotactic polymethyl methacrylate obtained by polymerizing in diethyl ether at −78 ° C. using lithium aluminum hydride as an initiator in place of the atactic polymethyl methacrylate used in Synthesis Example 1 ( Taxi tea 93 in triad display
%) Except that i-PMA was used in the same manner as in Synthesis Example 1.
I got AL. As a result of analyzing the tacticity of the obtained i-PMAAL by ¹³ C-NMR measurement in heavy DMSO, the syndiotacticity was 90% by triad.
Met. Using the obtained resin, a film was obtained and evaluated in the same manner as in Synthesis Example 1. Table 1 shows the physical property values of i-PMAAL and the measurement results of the moisture absorption, oxygen permeability, moisture permeability, and haze value of the obtained film.

Synthesis Example 4 Atactic polyallyl alcohol (a-PAAL)
Synthesis of Azobisisobutyronitrile as a catalyst instead of the atactic polymethyl methacrylate used in Synthesis Example 1, except for using atactic polyethyl acrylate obtained by polymerizing in toluene at 80 ° C. In the same manner as in Synthesis Example 1, a-PAAL was obtained. Using the obtained resin, a film was obtained and evaluated in the same manner as in Synthesis Example 1. Table 1 shows the physical property values of a-PAAL and the measurement results of the moisture absorption, oxygen permeability, moisture permeability, and haze value of the obtained film.

Synthesis Example 5 Styrene-methallyl alcohol random copolymer (S
Synthesis of T-MAAL) Styrene-methyl methacrylate random copolymer obtained by polymerization at 80 ° C. in toluene using azobisisobutyronitrile as a catalyst instead of the atactic polymethyl methacrylate used in Synthesis Example 1 ST-MAAL (styrene content 75 mol%, methallyl alcohol content 25 mol) in the same manner as in Synthesis Example 1 except that a polymer (styrene content 75 mol%, methyl methacrylate content 25 mol%) was used. %). Using the obtained resin, a film was obtained and evaluated in the same manner as in Synthesis Example 1. Table 1 shows the physical property values of the ST-MAAL, and the measurement results of the moisture absorption, oxygen permeability, moisture permeability, and haze value of the obtained film.

Reference Example 1 An ethylene-vinyl alcohol copolymer (ethylene content 32 mol%, saponification degree 99.5%) was formed into a single layer under the same conditions as in Synthesis Example 1 to obtain a film, which was evaluated. Was. The results are summarized in Table 1.

Reference Example 2 A commercially available biaxially stretched polypropylene film (OPP, “Tocello OP U-1” manufactured by Tosello Co., Ltd., melting point: 155 ° C.)
The same evaluation as in Synthesis Example 1 was performed for a thickness of 20 μm). The results are summarized in Table 1.

[0092]

[Table 1]

Example 1 The pellet obtained in Synthesis Example 1 was used as an intermediate layer, and homopolypropylene “J103” manufactured by Grand Polymer, MI =
3.0 g / 10 min (230 ° C., 2160 g load), Vicat softening point 155 ° C.} inner and outer layers, maleic anhydride-modified polypropylene {Mitsui Petrochemical “Admer QF50”
0 ", MI = 5.3 g / 10 min (230 ° C., 2160 g
(Load) is an adhesive (AD) layer, and 5 layers of 3 types (PP / AD / a-PMA) with a co-extruder equipped with a T-type die.
AL / AD / PP = 400μ / 20μ / 20μ / 20μ
/ 400μ) to obtain a thermoforming sheet having an overall thickness of 860μm. Table 2 shows the measurement results of the oxygen permeation amount of the obtained sheet.

The sheet thus obtained was thermoformed into a cup shape (mold shape 70φ × 70 mm, drawing ratio S = 1.0) at a sheet temperature of 150 ° C. using a thermoforming machine (manufactured by Asano Seisakusho). 5kg / cm ² , plug: 45φ × 65m
m, syntax foam, plug temperature: 150 ° C., mold temperature: 70 ° C.). Table 2 shows the results of measuring the oxygen permeation amount of the obtained thermoformed container.

Examples 2, 3 and Comparative Examples 1, 2, 3 Instead of using the resin obtained in Synthesis Example 1 in Example 1, Synthesis Example 2 (Example 2) and Synthesis Example 3 (Example 3) And the resins obtained in Synthesis Example 4 (Comparative Example 1) and Synthesis Example 5 (Comparative Example 2) and the same EVOH used in Reference Example 1.
A thermoforming sheet was obtained and thermoformed to obtain a thermoformed container in the same manner as in Example 1 except that Comparative Example 3 was used. Table 2 summarizes the evaluation results of the obtained sheets and containers.

Example 4 In Example 1, instead of using homopolypropylene having a thickness of 400 μm as the inner and outer layers, high impact polystyrene (HIPS) having a thickness of 200 μm “Idemitsu Styrol ET61” manufactured by Idemitsu Petrochemical, MI = 3 g / 10
A thermoforming sheet was obtained and thermoformed in the same manner as in Example 1, except that min (2160 g load) was used. Table 2 shows the evaluation results of the obtained sheets and containers.

Comparative Example 4 A thermoforming sheet was prepared in the same manner as in Example 4 except that the same EVOH as that used in Reference Example 1 was used instead of the resin obtained in Synthesis Example 1 in Example 4. Was obtained and thermoformed to obtain a thermoformed container. Table 2 shows the evaluation results of the obtained sheets and containers.

Example 5 The pellet obtained in Synthesis Example 1 was used as an intermediate layer, and nylon 6 was used.
(PA-6) ｛MI = 7.2 g / 10 min (230 ° C., 2
160g load), "UBE nylon 1022" manufactured by Ube Industries
B "} as inner and outer layers, maleic anhydride-modified polyethylene {M
I = 3.3 g / 10 min (210 ° C., 2160 g load),
Adhesive (A) made by Mitsui Petrochemical “Admer SF600”
D) The layer is composed of 3 layers by a co-extruder equipped with a T-type die.
Seed 5 layer (PA-6 / AD / a-PMAAL / AD / PA
−6 = 50 μ / 5 μ / 20 μ / 5 μ / 50 μ) to obtain a thermoforming film having a total thickness of 130 μm. Table 2 shows the results of measuring the oxygen permeability and the moisture permeability of the obtained thermoforming film.

The thus-obtained thermoforming film was heated at a heater plate temperature of 100 ° C. for 1.5 seconds by a thermoforming machine (R530 manufactured by Mulchivac) to reduce the film temperature to about 85
° C, the mold shape (vertical: 130 mm, horizontal: 110
mm, depth: 50 mm, rectangular parallelepiped shape, drawing ratio S = 0.4
5) was formed using compressed air (atmospheric pressure 5 kgf / cm ² ) to obtain a thermoformed container. Table 2 shows the results of measuring the oxygen permeation amount of the obtained thermoformed container.

Comparative Example 5 A thermoforming film was prepared in the same manner as in Example 5, except that the same EVOH as that used in Reference Example 1 was used instead of the resin obtained in Synthesis Example 1. Get
Thermoforming was performed to obtain a thermoformed container. Table 2 shows the evaluation results of the obtained thermoforming film and thermoforming container.

[0101]

[Table 2]

[0102]

The multilayer structure for thermoforming according to the present invention has excellent gas barrier properties, especially gas barrier properties under high humidity, and also has excellent steam barrier properties, melt moldability and transparency. The resulting thermoformed container is useful as a container for food, medicine, and the like.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B65D 1/09 B65D 1/00 B // B29K 29:00 B29L 9:00

Claims (5)

[Claims] 1. A thermoforming multilayer structure having a layer composed of a gas barrier resin containing 30 mol% or more of a repeating structural unit represented by the following formula (1) and a layer composed of another thermoplastic resin. Embedded image (In the formula, R ¹ represents an alkyl group having 1 to ² carbon atoms, and R ² represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.) 2. The multilayer structure for thermoforming according to claim 1, wherein the thermoplastic resin is polyolefin, polystyrene or polyamide. 3. The thermoforming multilayer structure according to claim 1, further comprising a layer made of an adhesive resin between the layer made of a gas barrier resin and the layer made of a thermoplastic resin. 4. The multilayer structure for thermoforming according to claim 3, wherein the adhesive resin is a polyolefin modified with an unsaturated carboxylic acid or an anhydride thereof. 5. A thermoformed container obtained by thermoforming the multilayered structure for thermoforming according to claim 1.