JPH1035634A - Blow-molded container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart high barrier properties and minimize barrier-properties decrease which occurs when humidity is high, by forming and spreading a layer of high-barrier resin, formed from a specific composition, over a container made of a heat-resistant resin. SOLUTION: A layer made of a resin which is difficult to solve in hot water, composing a container, is resistant to water and formed from a composition of PVA and (meth)acrylic polymer. Also, the layer of resin which is difficult to solve in hot water is formed from a composition of PVA, (meth)acrylic polymer, and a hydroxyl-group-containing plasticizer. The (meth)acrylic polymer is at least one kind of a polymer selected from the group consisting of poly(meth)acrylic acid and its partial neutralized product. Further, other layer composing the container is a layer made of a heat-resistant resin, and the resin which allows blow molding and is resistant to heat generated in the process of sterilization and heat generated in the process of drying and heating is used in terms of heat resistance. Thus, remarkably high barrier properties to oxygen, carbon dioxide gas, and so on can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a blow-molded container containing at least a specific resin layer having excellent gas barrier properties and a heat-resistant resin layer. The present invention relates to a packaging container, such as a blow bottle, which can be suitably used for hermetically packaging foods, medicines, and the like that require blocking of oxygen and carbon dioxide.

[0002]

2. Description of the Related Art Plastic containers are light-weight, hard to break, and do not rust.
It is used as a container for packaging cosmetics and the like.
For example, polyethylene terephthalate (PET) containers are rapidly expanding their applications as packaging containers for edible oils, carbonated drinks, and the like, taking advantage of their excellent heat resistance, gas barrier properties, and fragrance retention properties. . However, in recent years, due to the sophistication of eating habits, it has been required to store foods and other packaged items for a longer period of time while preventing them from deteriorating or decaying, and as a response, plastic containers have been required. Higher gas barrier properties have been required than ever before.

Conventionally, as a means for imparting gas barrier properties to a plastic container, a latex of a vinylidene chloride copolymer (PVDC) or an aqueous solution of polyvinyl alcohol (PVA) is applied to the wall surface of the container. ,
A method of forming a gas barrier coating film, a method of forming a gas barrier resin such as PVDC or ethylene-vinyl alcohol copolymer (EVOH) as a core layer, a method of forming a multilayer with a thermoplastic resin layer, PVDC, EVOH, etc. A method of forming a container using an alloy of a gas barrier resin and a thermoplastic resin, and a method of depositing and forming a thin film of an inorganic oxide such as silicon oxide in the container have been proposed.

[0004]

However, in the above-mentioned method using the conventional resin for the gas barrier property imparting layer, the level of barrier property obtained is limited, and
Containers using PVA have problems such as lack of water resistance,
OH containers have drawbacks such as a significant decrease in gas barrier properties under high humidity, and PVDC containers may have environmental problems in disposal or incineration. The inorganic oxide vapor deposition method has problems such as being far from practical use at a technically immature stage. Under such circumstances, the above-mentioned conventional method has little possibility as a means for obtaining a significantly higher level of barrier properties, and there is an urgent need to consider a new countermeasure.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a plastic container that reliably solves the above-mentioned problems of the prior art.
It has a remarkably high barrier property against oxygen and carbon dioxide gas, and has a small decrease in barrier property under high humidity, has water resistance, and has little environmental problems when disposed or incinerated. To provide a blow molded container.

[0006]

Means for Solving the Problems As a result of earnest studies, the present inventors have found that a high-barrier resin layer formed of a specific composition is formed and coated on a blow-molded container made of a heat-resistant resin. It has been found that the above problem is solved. The present invention is based on the above findings.

That is, the present invention provides a blow-molded container comprising at least a layer of a poorly water-soluble resin formed of a composition comprising PVA and a (meth) acrylic acid-based polymer, and a layer formed of a heat-resistant resin. It is in. Further, a second aspect of the present invention is a blow molding method including at least a layer of a poorly water-soluble resin formed of a composition comprising PVA, a (meth) acrylic acid-based polymer and a hydroxyl group-containing plasticizer, and a layer formed of a heat resistant resin. It is to provide a molded container.
Further, a third object of the present invention is to provide a blow molded container in which the hot water hardly soluble resin layer is coated on at least one surface of a blow molded container made of a heat resistant resin.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

(Heat-water-poorly water-soluble resin layer) The layer made of the hot-water-insoluble resin constituting the blow-molded container of the present invention has water resistance and imparts a high gas barrier property to the blow-molded container of the present invention. Play a role. In the present invention, the term “hardly water-soluble resin” refers to about 1 g of a film-like substance made of the resin,
After pouring into 500 cm ³ of water at 0 ° C. and immersing for 10 minutes, the insoluble matter is recovered and, when dried, 80% by mass or more, preferably 85% by mass or more of the mass before immersion, as insoluble matter Refers to the recovered resin.

In the present invention, the hardly water-soluble resin layer is made of P
It is formed from a composition comprising VA and a (meth) acrylic acid-based polymer. Further, the hardly water-soluble resin layer is made of PV
A, formed from a composition comprising a (meth) acrylic acid-based polymer and a hydroxyl group-containing plasticizer.

As the PVA, a conventionally known PVA can be used. In view of exhibiting a suitable gas barrier property in combination with a (meth) acrylic acid-based polymer, the degree of saponification is usually 95 mol. % Or more and an average degree of polymerization in the range of 300 to 2500 is preferable.

On the other hand, a (meth) acrylic acid-based polymer is
It is at least one polymer selected from the group consisting of poly (meth) acrylic acid and partially neutralized products thereof. Poly (meth) acrylic acid is a compound containing two or more carboxyl groups, and more specifically, polyacrylic acid,
Examples thereof include polymethacrylic acid, a copolymer of acrylic acid and methacrylic acid, or a mixture thereof.

The partially neutralized poly (meth) acrylic acid is obtained by converting the above poly (meth) acrylic acid into at least one selected from the group consisting of sodium hydroxide, lithium hydroxide, potassium hydroxide and ammonium hydroxide. What carried out partial neutralization using the basic compound of this is preferable. In such an embodiment, the degree of neutralization is greater than 0 and not more than 20%,
Preferably it is more than 0 and 18% or less. By using the partially neutralized product, the gas barrier property of the hardly water-soluble resin layer can be further improved, and coloring which is considered to be caused by thermal decomposition or the like can be reduced.

Here, the degree of neutralization is obtained by the following equation. Degree of neutralization = (A / B) × 100 A: 1 g of partially neutralized (meth) acrylic acid-based polymer
The total number of moles of neutralized carboxyl groups therein. B: Total number of moles of carboxyl groups before partial neutralization in 1 g of (meth) acrylic acid-based polymer to be partially neutralized. In addition, the above-mentioned "moles of carboxyl groups" refers to the number of moles of acrylic acid using the molecular weight of 72 g / mol, which is a monomer unit of acrylic acid, from the mass of the acrylic acid-based polymer. Is to determine the number of moles from the mass of the methacrylic acid-based polymer using a molecular weight of 86 g / mol which is a monomer unit of methacrylic acid.

The mixing ratio of PVA to the (meth) acrylic acid polymer is such that PVA: (meth) acrylic acid polymer = 9 from the viewpoints of gas barrier properties, thermal stability, and productivity.
5: 5 to 5:95, preferably 80:20 to 5:
95 (mass ratio). When the mixing ratio of PVA is 9
If it is more than 5 or less than 5, the gas barrier properties and water resistance are not sufficient.

In the present invention, the resin layer that is hardly soluble in hot water is
When it is necessary to impart flexibility or low-temperature strength,
A composition comprising PVA and a (meth) acrylic acid-based polymer may contain a hydroxyl group-containing plasticizer.
The plasticizer is a plasticizer having at least one hydroxyl group, preferably a plasticizer having two or more hydroxyl groups, among those conventionally known as plasticizers for plastics. The molecular weight is not particularly limited, but is preferably in the range of 3000 or less, preferably 1000 or less, more preferably 700 or less from the viewpoint of gas barrier properties of the resulting hardly water-soluble resin.

Specific examples of the plasticizer include ethylene glycol, trimethylene glycol, propylene glycol, tetramethylene glycol, 2,3-butanediol, 1,3-butanediol, pentamethylene glycol, hexamethylene glycol, diethylene glycol, and triethylene glycol. Examples include ethylene glycol, trimethylolpropane, sorbitol, mannitol, dulcitol, erythritol, and glycerin. These may be used in a mixture. Among them, glycerin and sorbitol are preferable from the viewpoint of gas barrier properties and productivity of the hardly water-soluble resin.

The hydroxyl group-containing plasticizer is used in an amount of 1 to 50 parts by mass, preferably 2 to 40 parts by mass, more preferably 5 to 30 parts by mass based on 100 parts by mass of the total amount of the PVA and the (meth) acrylic acid-based polymer. Range. When the amount of the hydroxyl group-containing plasticizer is less than 1 part by mass, the flexibility is not sufficient. On the contrary, when the amount of the hydroxyl group-containing plasticizer exceeds 50 parts by mass, the gas barrier property of the hardly water-soluble resin layer is greatly reduced, and Bleeding tends to occur on the surface of the resin layer, and there is a problem in using the container.

In the present invention, the composition is used as a coating solution in the form of a solution dissolved or suspended in a solvent. Such a solvent is not particularly limited as long as it dissolves or suspends PVA, a (meth) acrylic acid-based polymer or a hydroxyl group-containing plasticizer. Preferred examples of the solvent include water, alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, and a mixed solvent of water and the alcohol. Among them, water is preferred from the viewpoint of handling properties and the like.

The solvent is used in an amount of 100 to 50 parts by weight based on 100 parts by mass of the total amount of PVA and (meth) acrylic acid-based polymer.
00 parts by mass, preferably in the range of 200 to 2000 parts by mass. If the amount of the solvent is less than 100 parts by mass, it is difficult to apply the composition to the container with good uniformity of the thickness.
If the amount is more than 00 parts by mass, the concentration of the solution becomes low, so that there is a problem that the production cost is increased.

The composition is prepared by adding and mixing the above components, dissolving or suspending PVA or a hydroxyl group-containing plasticizer in a solvent, and then adding (meth) acrylic acid or a partially neutralized product thereof. And the method of polymerization. Further, if necessary, various additives can be added to the composition within a range that does not impair the purpose of the present invention. In particular, it is preferable to add an inorganic salt such as sodium hypophosphite from the viewpoint of promoting the formation of a resin layer which is hardly soluble in hot water than the composition and reducing the coloring of the resin which is hardly soluble in hot water. The amount added is PVA and (meth)
The amount is preferably 20 parts by mass or less based on the total amount (100 parts by mass) of the acrylic acid-based polymer.

In the formation and application of the hardly water-soluble resin layer from the above composition, a solution comprising the composition is applied to form a coating film, and then the solvent is removed from the coating film by drying or the like. After that, by performing heat treatment by blowing hot air,
Preferably, it can be carried out (described later).

(Heat-Resistant Resin Layer) One of the layers constituting the blow-molded container of the present invention is a layer made of a heat-resistant resin.
This resin may be any resin that can be blow-molded, and as heat resistance, heat when sterilizing the container or the like,
The resin is not particularly limited as long as it is a resin that can withstand the heat of drying and heat treatment in a step of forming and applying a hardly water-soluble resin layer from the composition (described later).

Specific examples of the heat-resistant resin include PET, polyethylene naphthalate (PEN), polycarbonate, polyphenylene sulfide, polyphenylene oxide, polyether ketone, polyarylate, and poly-4.
-Methylpentene-1 or a mixture thereof is preferred. Incidentally, the heat-resistant resin used in the present invention, as long as the requirements for the heat-resistant resin is not impaired, a heat stabilizer, a lubricant, a plasticizer,
Various additives such as fillers and pigments can be added.

(Method of Manufacturing Blow Molded Container) The method of manufacturing the blow molded container of the present invention is not particularly limited, but a preferred embodiment is a step of manufacturing a blow molded body using a heat-resistant resin. And a step of forming and applying a hardly water-soluble resin layer on at least one surface of the wall surface of the molded article. Here, "blow molded body"
The term includes not only containers manufactured by blow molding, but also parisons and preforms (test tube-shaped bottomed parisons) that are precursors for manufacturing containers.

The blow molded article can be manufactured by molding the heat-resistant resin by a known method such as direct blow, injection blow, stretch blow and the like. These molding methods may be appropriately selected depending on the use of the blow molded article as the final product.

The blow-molded article may be a single layer made of a heat-resistant resin or a multilayer. As an example of the multilayer molded body, one composed of a PET layer and a polyarylate layer is preferable. Further, a multilayer molded body of a heat-resistant resin and a conventionally known thermoplastic resin such as a polyamide or an olefin-based resin may be used.

The formation and coating of the hardly water-soluble resin layer on the blow-molded body is performed by dissolving the composition in a solvent on at least one side of the wall of the blow-molded body (that is, on one or both walls of the blow-molded body). Alternatively, the suspended solution (coating solution)
First, a coating film is formed by a method of coating or atomizing (spraying), or a method of immersing a blow molded article in the solution, and then the solvent is removed from the coating film by drying or the like, and then, hot air blowing is performed. A heat treatment (preferably in the range of 160 to 300 ° C., more preferably 180 to 260 ° C.) is performed by attaching or the like, and the heat treatment can be suitably performed. By the heat treatment, a resin layer formed from the composition becomes a resin layer of the above-mentioned “hardly water-soluble resin”.

When forming and coating the hardly water-soluble resin layer on the blow molded article, the blow molded article is required to prevent shrinkage of the blow molded article due to heat such as drying and heat treatment and to improve dimensional stability. Subsequent to the step of manufacturing the blow molded article, a step of heat setting the blow molded article may be inserted. The heat setting can be performed by a known method.

The formation and coating of the hardly water-soluble resin layer on the blow-molded article is carried out, specifically, by forming a coating film of a coating solution comprising the composition on at least one side of the wall surface of a parison or a preform. It can be suitably performed by a method of performing blow molding, a method of performing molding and heat treatment, a method of forming a coating film of a coating solution of a composition on at least one surface of a wall surface of a blow molding container, and performing a drying or heat treatment. it can.

In particular, from the viewpoint of heat resistance of the obtained blow-molded article, a preform made of a heat-resistant resin is produced by injection blow molding, and the preform is blow-molded to a size larger than that of the final product blow-molded container (primary blow molding). Molding), and then forming a coating film of a coating solution of the composition on at least one side of the wall surface of the obtained primary molded product, and subjecting the molded product formed with the coating film to heat fixing treatment and heat treatment in an oven. (Usually, the molded product shrinks during this process.) Then, it is put into a mold and blow-molded (secondary molding) again.
A method (double blow method) of forming a blow-molded container on which a hardly water-soluble resin layer is formed and coated is preferable.

In the formation and coating of the hardly water-soluble resin layer on the blow-molded article, if it is necessary to make the adhesion between the wall surface of the blow-molded article and the hardly water-soluble resin layer more tight, the blow A known adhesive is applied to the wall surface of the molded body,
Alternatively, after performing a known surface modification treatment such as a corona discharge treatment, a hot water sparingly soluble resin layer can be formed and applied. Further, for the purpose of protecting the hardly water-soluble resin layer formed and applied to the blow molded body, a known thermoplastic resin such as the heat-resistant resin or polyamide or olefin resin was dissolved or suspended in a solvent. A solution can be applied on the surface of the hardly water-soluble resin layer.

(Gas Barrier Property) The hot water sparingly soluble resin layer constituting the blow molded container of the present invention is characterized by having water resistance and excellent barrier properties against oxygen, carbon dioxide gas and the like. Especially,
When the blow-molded container is used for applications that require high oxygen barrier properties, by controlling the heat treatment conditions, the thickness of the resin layer (thickness: 3 μm) of the hardly water-soluble resin layer is reduced.
Oxygen permeability at 80 ° C. and 80% RH is approximately 100 cm ³
/ M ² · day · atm or less, and further 80 cm ³ / m ² ·
It is preferable to adjust the value to not more than day · atm.

(Thickness of Each Layer) The thickness of each layer constituting the blow-molded container of the present invention depends on various physical properties (eg, oxygen gas barrier properties, rigidity, etc.) to be imparted to the container, or the material of each layer. The thickness may be appropriately selected as described above, but usually the thickness is preferably as follows. The heat-resistant resin layer is 10 to 3000 μm, preferably 50 to 1500 μm. The hardly water-soluble resin layer is 0.1 to 30 μm, preferably 0.2 to 10 μm.

[0035]

【Example】

[Examples 1 to 5, Comparative Examples 1 to 5] (Production of blow molded container) As a heat-resistant resin, PET (J055; intrinsic viscosity (IV value) manufactured by Toray Industries, Inc.)
0.7), a preform is prepared by injection molding, and then the preform is stretched in the machine direction and the transverse direction while being blown to a volume of about 1.5 times the volume of the final product container. A molded article (primary molding) was obtained. Thereafter, the molded body was kept in an oven controlled at 225 ° C. and subjected to a heat-setting treatment (during the heat-setting treatment, the molded body shrunk to about 0.9 times the volume of the container as the final product). Then, it is put again in the mold, blow-molded (secondary molding), and biaxially stretched PET bottle (capacity = 500 ml,
Straight body diameter = 100 mm, PET layer thickness of straight body = 25
0 μm).

(Formation and Coating of Hot-Water-Resistant Resin Layer on Blow Molded Container) As polyacrylic acid (PAA), PAA manufactured by Wako Pure Chemical Industries, Ltd. (viscosity = 8 to 12 Pa · s, 3
(0 ° C .; number average molecular weight = 150,000) and diluted with water to prepare a 20% by mass aqueous solution.
To this 20% by mass aqueous solution, a calculated amount of sodium hydroxide based on the number of moles of the carboxyl group of PAA was added and dissolved to prepare a partially neutralized (PAANA) aqueous solution having a degree of neutralization of 10%. On the other hand, Povar 105 (degree of saponification = 98.5 mol%; average degree of polymerization = 500) manufactured by Kuraray Co., Ltd. was diluted with water to prepare a 20% by mass aqueous solution. The above PAANA solution and PVA solution are
The mixture was mixed so as to have a mass ratio (solid content) shown in Table 1 to prepare a 20% by mass aqueous solution of the mixture. Next, the mixture aqueous solution was applied to the outer wall surface of the PET bottle,
Water was evaporated and removed in an oven adjusted to ° C. to obtain a PET bottle on which a dried film was formed. Then 230 ° C
Blow-molded container of the present invention in which a heat treatment is performed by holding the PET bottle for 30 seconds in an oven adjusted to a temperature, and a resin layer (thickness = 3 μm) hardly soluble in hot water is formed and coated on the outer wall surface of the PET bottle. (Examples 1 to 5) were obtained.

A sample was cut from the body of the blow-molded container manufactured as described above, and a Modern Control was cut out.
The oxygen permeability (30 ° C., 80% RH) was measured using OX-TRAN 2/20 manufactured by ol Corporation. The results are shown in Table 1. Further, the hot water insoluble resin layer was scraped off from the blow-molded container, and about 1 g of the resin layer was poured into 500 cm ³ of water at 80 ° C., immersed for 10 minutes, and the insoluble matter was recovered. Are shown in Table 1.

On the other hand, as a comparative example, a PET bottle (Comparative Example 1), a PET bottle having a resin layer made of PAA alone on the outer wall surface and coating (Comparative Example 2), and a PAANA A single resin layer was formed and coated (Comparative Example 3).
A resin layer composed of VA alone was formed and coated (Comparative Example 4), a mixture aqueous solution composed of PAANA and PVA was applied to the outer wall surface of a PET bottle, and water was evaporated and removed in an oven adjusted to 100 ° C. Then, a dried film was formed, and the oxygen permeability of a sample not subjected to the subsequent heat treatment (230 ° C., 30 seconds) (Comparative Example 5) was measured. In addition, in Comparative Examples 2 to 5, the resin layer of the coating film was scraped off, and the insoluble content in water at 80 ° C. was measured.

[0039]

[Table 1] 組成 Composition of coating (resin) layer (* 1) Oxygen permeability (* 2) Water resistance (* 3) ＰＡ PAA PAANA Na PVA ─────────────────── ─────────────── Example 1-30 70 2.7 85 Example 2-50 50 0.6 90 Example 3-70 30 0.1 95 Example 4-80 20 0.5 90 Example 5-90 10 2.4 85 Comparative Example 1---6.0-Comparative Example 2 100--6.00 Comparative Example 3-100-6.00 Comparative Example 4-- 100 6.0 0 Comparative Example 5-70 30 6.0 0 ( * 1) Unit: parts by mass (* 2) Unit: cm ³ / m ² · day · atm; measured at 30 ° C. and 80% RH (* 3) Unit: mass%

Examples 6 to 9, Comparative Example 6 A partially neutralized product of polyacrylic acid having the degree of neutralization shown in Table 2 (PAAN
a) or unneutralized polyacrylic acid (PAA) and PV
An aqueous solution (concentration: 20% by mass) containing A and A at a mass ratio (solid content) of 70:30 was prepared, and using this aqueous solution,
In the same manner as in Examples 1 to 5, blow-molded containers of the present invention (Examples 6 to 9) were obtained in which a resin layer hardly soluble in hot water was formed and coated on the outer wall surface of the PET bottle. Using the blow molded container thus obtained, the oxygen permeability was measured in the same manner as in Examples 1 to 5. The results are shown in Table 2. Table 2 shows the results obtained by shaving off the hardly water-soluble resin layer from the blow-molded container and measuring the insoluble content in water at 80 ° C.

On the other hand, as a comparative example, P having a neutralization degree of 50%
PAANA was prepared in the same manner as in Examples 7 to 9 using AANA.
And an aqueous solution (concentration: 20% by mass) containing PVA at a mass ratio (solid content) of 70:30. Next, using this aqueous solution, a blow-molded container (Comparative Example 6) in which a resin layer was formed and coated on the outer wall surface of the PET bottle was obtained. Table 2 shows the measurement results of the oxygen permeability. Comparative Example 6
The resin layer of the coating film was scraped off, and the insoluble content in water at 80 ° C. was measured. The results are shown in Table 2.

[0042]

[Table 2] 組成 Composition of coating (resin) layer (* 1) Oxygen permeability (* 2) Water resistance (* 3) ─────────────── PAANA PVA ──────────────────── ────────────── Example 6 70 (degree of neutralization = 0%) 30 4.4 85 Example 7 70 (degree of neutralization = 5%) 30 0.6 90 Example 870 (degree of neutralization = 10%) 30 0.1 95 Example 9 70 (degree of neutralization = 15%) 30 2.4 85 Comparative Example 6 70 (degree of neutralization = 50%) 30 6.0 70 ───────────────────────────────── (* 1) Unit: mass part (* 2) Unit: cm ³ / m ² · day · atm; measured at 30 ° C. and 80% RH (* 3) Unit: mass%

Example 10 PAANA having a degree of neutralization of 10%
Glycerin as a hydroxyl group-containing plasticizer in an aqueous solution (concentration: 20% by mass) containing styrene and PVA at a mass ratio (solid content) of 70:30, and the total amount (solid content) of PAANA and PVA
An aqueous solution was prepared by adding 20 parts by mass to 100 parts by mass. Next, the aqueous solution was blow-molded to a volume of about 1.5 times the volume of the final product container while stretching the preforms prepared in Examples 1 to 5 (the preform was stretched in the vertical and horizontal directions). On the outer wall surface of
The compact was kept in an oven adjusted to 100 ° C. to evaporate and remove water. Then, it was held in an oven adjusted to 230 ° C. for 30 seconds to perform a heat setting treatment and a heat treatment (during this treatment, the compact shrunk to a volume of about 0.8 times the volume of the final product container). Then, it is put into a mold again, blow-molded (secondary molding), and a hot water sparingly soluble resin layer (thickness = 3μ)
m) formed and coated, a biaxially stretched PET bottle which is a blow-molded container of the present invention (capacity = 500 ml, straight body diameter = 100 mm, thickness of straight body PET layer = 250 μm)
Was manufactured. In addition, no cracks or the like were generated on the surface of the obtained PET bottle coated with the hardly water-soluble resin. Next, the oxygen permeability was measured in the same manner as in Examples 1 to 5. The result is 3.8 cm ³ / m ² · day · atm
Met. Further, the result of measuring the insoluble content of the hardly water-soluble resin layer in water at 80 ° C. was 85% by mass.

As is evident from the above examples, the P on which the hardly water-soluble resin layer formed from the composition of the present invention was applied was coated.
It can be seen that the ET bottles (Examples 1 to 10) have excellent gas barrier properties and water resistance. On the other hand, PET bottles not coated with the hardly water-soluble resin layer of the present invention (Comparative Examples 2 to 5)
6) was inferior in gas barrier properties and water resistance.

[0045]

The present invention relates to a blow-molded container containing at least a resin layer formed of a specific composition and a heat-resistant resin layer. The container has a significantly higher barrier against oxygen, carbon dioxide and the like. It has the characteristics of being excellent in water resistance and having a small decrease in barrier property under high humidity.
In addition, it also has the characteristic of having little impact on the environment when disposed or incinerated. INDUSTRIAL APPLICABILITY The blow-molded container of the present invention can be suitably used for hermetic packaging of foods, pharmaceuticals, and the like that require blocking of oxygen and carbon dioxide.

Continuing on the front page (72) Inventor Hiroyuki Oba 18-13 Kamitamari, Tamari-mura, Niigata-gun, Ibaraki Pref.Resin Processing Technology Center, Kureha Chemical Industry Co., Ltd. 18-13 Kureha Chemical Industry Co., Ltd. Resin Processing Technology Center (72) Inventor Junji Yoshii 20-20 Hinodecho, Noda City, Chiba Prefecture

Claims (3)

[Claims] 1. A blow-molded container comprising at least a layer of a poorly water-soluble resin formed of a composition comprising polyvinyl alcohol and a (meth) acrylic acid-based polymer, and a layer comprising a heat-resistant resin. 2. The container according to claim 1, wherein the composition contains a hydroxyl group-containing plasticizer. 3. The container according to claim 1, wherein the blow-molded container made of a heat-resistant resin is coated with the hardly water-soluble resin layer on at least one surface.