JPH08244781A - Container, production thereof and preform - Google Patents

Abstract

PURPOSE: To enhance gas barrier properties and to facilitate production by forming a resin film containing a polyvinyl alcohol type coating agent on the surface of a container composed of biodegradable plastic. CONSTITUTION: The surface of the body part 4 of a preform is subjected to activation treatment so as to chemically adsorb a gas barrier resin. The treated surface of the preform is coated with a coating agent composed of a polyvinyl alcohol type coating agent. The coated preform is heated to stretchable temp. and the flange part 3 thereof is set between a pair of openable and closable molds 9, 10 and compressed air is supplied while the preform is stretched by a stretching rod 11 to mold a plastic bottle 7. The preform is expanded by stretching and blow to be molded into the blow bottle 7 and the molecules of the resin film of the preform are stretched, cooled and solidified to become a resin film 8' and the gas barrier properties and strength of the bottle are enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container which is excellent in gas barrier properties such as oxygen barrier property, carbon dioxide barrier property and odor barrier property and is naturally decomposed, and a method for producing the same.

[0002]

2. Description of the Related Art Recently, plastic containers are used in various containers because they are lighter in weight than glass and have excellent impact resistance.

In particular, polyester bottles made by stretch blow molding, especially polyethylene terephthalate (PE
T), and polyolefin bottles, especially polypropylene (pp) bottles, have excellent physical properties (transparency, gloss, lightness, appropriate rigidity, etc.), such as carbonated beverages, seasonings, cosmetics, Widely used as a container for liquid detergent, etc.

[0004]

However, since such stretch-blown bottles made of polyethylene terephthalate or polypropylene are hard to corrode, there is a problem that if they are scattered and left as dust in a natural environment, they easily cause environmental pollution. is there. In order to solve such a problem, plastics that are easily decomposed by microorganisms are being researched today. Such biodegradable plastics have oxygen barrier property, carbon dioxide barrier property, odor barrier property, etc. There is a problem that the gas barrier property is poor and the storability of the contents is not good.

In order to improve such a point, there is a method of wrapping a film having excellent gas barrier property such as ethylene vinyl acetate (EVOH) and nylon (Ny). Such a method has a problem that the machine is complicated, a range of molding conditions is narrowed, and a cost is increased.

The present invention has been made by paying attention to such a problem, and has a container which is biodegradable and has an excellent gas barrier property, is easy to manufacture, and is low in cost and a method for manufacturing the container. The purpose is to provide preforms.

[0007]

In order to solve the above-mentioned problems, a container according to claim 1 of the present invention has a resin coating containing a polyvinyl alcohol-based coating agent on the surface of a container made of biodegradable plastic. It is characterized by being formed.

The container according to claim 2 of the present invention is the container according to claim 1, wherein the biodegradable plastic is polylactic acid or aliphatic polyester, hydroxypolyester, polycaprolactone or polyamino acid. It is characterized by including.

Further, the container according to claim 3 of the present invention is the container according to claim 1 or 2, wherein the resin coating contains 5% by weight to 70% by weight of a metal alkoxide or a hydrolyzate of the metal alkoxide. The metal of the metal alkoxide contains either silicon or aluminum.

The preform of claim 4 of the present invention is a preform for molding the container of claims 1 to 3, the material of which is polylactic acid, aliphatic polyester, or hydroxy polyester, Alternatively, it is characterized in that it is made of either polycaprolactone or polyamino acid, and a resin coating film made of a polyvinyl alcohol-based coating agent is formed on the surface.

The preform of claim 5 of the present invention is the preform of claim 4, wherein the resin coating contains 5 wt% to 70 wt% of either a metal alkoxide or a metal alkoxide hydrolyzate. It is characterized in that the metal of the metal alkoxide contains either silicon or aluminum.

A method for producing a container according to claim 6 of the present invention is a method for producing a container for forming the container according to any one of claims 1 to 3, which comprises polylactic acid, an aliphatic polyester, a hydroxypolyester, or a polyester. After activating the surface of the preform containing either caprolactone or polyamino acid, at least the resin containing the polyvinyl alcohol-based coating agent is coated on the surface of the preform, and the preform is heated and then the mold is heated. It is characterized in that it is disposed in the cavity of and stretch-blow-molded.

[0013]

According to the container of claims 1 and 2 of the present invention,
The container is made of biodegradable plastic such as polylactic acid, fatty acid polyester, hydroxypolyester, polycaprolactone, or polyamino acid, and the surface thereof is coated with a polyvinyl alcohol-based coating agent to form a resin film. As a result, the gas barrier property is improved, and if it is left outdoors after use and gets wet with water drops, it swells and elutes, and is eventually biodegraded.

According to the container of claim 3 of the present invention, in addition to the function of the container of claims 1 and 2, in the range of 5 to 70% by weight of the metal alkoxide or the metal alkoxide hydrolyzate in the resin coating. Since it is included, the gas barrier property is further improved compared to the case where it is not included.

According to the preform of claim 4 of the present invention, in addition to the function of the container of claims 1 and 2, when the preform is set in a mold and stretch blow molded, the biodegradable plastic is stretched. As the container is formed, the coating agent on the surface is stretched and oriented and crystallized, and the gap between the resins is narrowed, so that the gas barrier property is improved. Moreover, according to the preform of the fifth aspect, since the metal alkoxide or the metal alkoxide hydrolyzate is contained, the gas barrier property is further improved.

According to the method for producing a container of claim 6 of the present invention, the time and effort required for producing the container are short, the production time is short as compared with the laminating method, and the production cost is low. It is possible to obtain a container having the above-mentioned property, and furthermore, even if it is scattered and left outside after use, it biodegrades and disappears, thus preventing environmental pollution.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A resin coating container and a manufacturing method thereof according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a sectional structure of a preform according to an embodiment of the present invention.

This preform 1 forms a plastic bottle by being held in a pair of molds that are opened and closed and stretched and blown. Screw part 2 protruding outside the mold
And a flange portion 3 supported by the edge portion of the die on the side of the air blowing port to play a role of supporting the preform during stretch molding, and is blown with compressed air to be biaxially stretched to expand into a plastic bottle shape. It is composed of a bottomed cylindrical body 4. A resin coating 5 having an excellent gas barrier property is formed on the surface of the body portion 4 of the plastic 1 (the outer surface of the cylindrical portion in this embodiment). The mold used for stretch blow molding is the same as a known mold for stretch blow molding a normal preform.

The material of the preform 1 may be a so-called biodegradable polymer compound which can be stretch blow molded and biochemically decomposed by microorganisms. Specifically, polylactic acid and fat having proper stretchability can be used. Examples thereof include group polyesters, hydroxy polyesters, polycaprolactones, polyamino acids, and the like.

The polylactic acid may be polylactic acid which is a copolymer with tartaric acid, glycolic acid, α-malic acid, polyethylene glycol, lactone or the like.

The aliphatic polyester may be an aliphatic polyester obtained by polycondensing a dicarboxylic acid such as adipic acid, succinic acid or oxalic acid and a glycol such as ethylene glycol, propylene glycol or butanediol.

As the hydroxy polyester,
3-Hydroxybutyrate A 3-hydroxyvalerate copolymer is preferred.

It should be noted that these plastics may contain known additives such as an ultraviolet absorber, a plasticizer, a coloring agent, a crystal nucleating agent, an antistatic agent and the like. The method of molding the preform 1 includes direct blow molding method, injection molding method, injection blow molding method,
There are an extrusion molding method, a vacuum molding method, a compression molding method, and a machining method, but a combination thereof may be used.

When the gas barrier resin coating 5 is formed on the preform 1, the gas barrier resin is chemically adsorbed on the surface of the bottomed cylindrical body 4 of the molded preform 1. , Perform activation processing. As a method of this activation treatment, there are a corona treatment by corona discharge, an ozone treatment, etc. in addition to the flame treatment in which the flame F is applied as shown in FIG. During the frame processing of the preform 1, the flame is applied while rotating the preform 1 around the center line extending in the coaxial direction. As a result, the entire circumference of the body 4 of the preform 1 is activated.

After activating the preform 1, the preform 1 is dipped in a liquid tank 6 containing a coating agent 5 as shown in FIG. 3 to apply the coating agent 5 on the surface of the preform 1. The coating method of the coating agent 5 includes dipping, spraying, brushing and the like.

As the coating agent 5 for forming the resin film (see FIG. 4), a coating agent which is easily decomposed and discharged by microbial decomposition, hydrolysis, etc. is preferable, and a polyvinyl alcohol type coating agent (PVA) is used. These coating agents 5 enable stretch blow molding after coating and improve oxygen barrier properties, carbon dioxide barrier properties, and odor barrier properties.

The coating agent 5 contains an alkoxide or an alkoxide hydrolyzate, and the alkoxide or the alkoxide hydrolyzate contained in the coating agent is contained in a concentration of 5% by weight to 70% by weight.

The alkoxide contained may be tetraethyl orthosilicate (Si (OC ₂ H ₅ ) ₄ ), triisopropylaluminum, (Al (OC ₃ H ₇ ) ₃ ), or the like, of the general formula M (OR) n (M is Si , Al, Zr, and other metals, and R is an alkyl group). Among them, the metal M is S
i and Al have excellent alkoxide characteristics.

The amount of alkoxide or alkoxide hydrolyzate added varies depending on the draw ratio, the type of coating agent applied, etc., and is not generally determined, but the uniformity of the coating film 8'of the blow bottle 7 obtained after molding is From the point, 70% or less is preferable, and 40% is more preferable.
It is the following. Also, depending on the thickness of the coating film 8'to be formed, the gas barrier property of the blow bottle is improved only by adding a small amount of alkoxide or alkoxide hydrolyzate, so the lower limit may be any percentage, but more It is preferably at least 5%.

When PVA absorbs water, it swells and its gas barrier property deteriorates. However, by coating the preform 1 with the coating agent 5 in advance, the preform 1 is stretched, blown and cooled to form oriented crystals, The deterioration of the barrier property can be suppressed.

The coating agent 5 also includes a polyvinyl alcohol-based coating agent (hereinafter, PVA) containing no alkoxide. Even with a coating agent containing no alkoxide, the activation treatment is performed to such an extent that the surface of the preform 1 can be coated.

Since the coating agent 5 is excellent in gas barrier properties such as oxygen barrier property, carbon dioxide barrier property and odor barrier property, it may be coated with the coating agent alone, but it is preferable that the coating agent 5 contains an alkoxide or an alkoxide hydrolyzate. preferable.

The preform 1 coated with the coating agent 5 is first dried before being stretch-blown by heating the preform 1 coated with the coating agent by infrared radiation from an infrared heater or heating in an oven. While doing so, the surface temperature of the body portion 4 of the preform 1 is raised to 100 ° C to 150 ° C. After the temperature of the preform 1 is raised, the preform 1 is gradually cooled. 60 ° C when the material of preform 1 is polylactic acid
To 100 ° C, and when the material of preform 1 is aliphatic polyester, it is cooled to 70 ° C to 130 ° C. The temperature distribution of the part 4 is made uniform.

Preform 1 heated to a temperature at which it can be stretched
The flange portion 3 is set between a pair of molds 9 and 10 that can be opened and closed, and while being stretched by the stretching rod 11, compressed air is supplied from an air nozzle (not shown) to mold a plastic bottle.

The pressure and speed of the drawing rod 11 depend on the shape of the preform 1 to be drawn and the shape of the final molded product, but are usually at a pressure of 3 to 20 Kgf · cm ⁻² and a speed of ^{2 to} 50 cm / s. To move.

The compressed air sets the primary blow pressure and the secondary blow pressure, and the primary blow pressure is 1 to 10 Kgf · c.
m ⁻² , and the secondary blow pressure is about 10 to 40 kg · cm ⁻² . The primary blow pressure and the secondary blow pressure do not necessarily have to be separated, and stretch blow molding can be performed with a single pressure, and the molding method is not limited.

FIG. 5 shows a plastic bottle 7 obtained by stretch blow molding the preform 1 of this embodiment.
The plastic bottle 7 has a resin coating 8 ′ on the outer peripheral surface. This resin coating 8 ′ is stretched with the resin coating 8 coated with the preform 1 when the preform 1 is stretch-blown.

By stretching and blowing, the preform 1 swells to form the blow bottle 7, and at the same time, the molecules of the resin coating 8 of the preform 1 are oriented and crystallized by stretching to reduce the gap between the resin coating 8'and the resin. The coating 8 ′ is cooled and solidified to improve the gas barrier property and the strength. Further, since the preform 1 is coated in advance, the coating space can be small and the machine can be made compact.

Since polyvinyl alcohol PVA is easily hydrolyzed, it decomposes even if it is discarded outdoors such as when the container becomes unnecessary. A metal alkoxide when PVA is decomposed or a metal alkoxide hydrolyzate is naturally present as a metal oxide (general formula M _n O _m , M is a metal), and when the container is no longer needed, it can be used outdoors. There is no concern about environmental pollution even if it is discarded and left in the ground and absorbed into the ground.

It is also conceivable to subject the uncoated preform 1 to stretch blow molding to form a plastic bottle, which is then subjected to a frame treatment or the like for coating treatment. The coating resin coating may be applied to the inner surface of a plastic bottle or tray or cup.

Further, a hot parison method or a cold parison method can be considered as a manufacturing method for coating the coating agent 5 after forming the blow bottle. Furthermore, although the stretch blow molding method has been described as an example of the container manufacturing method in the above-mentioned embodiment, the container manufacturing method of the present invention is not limited, and a direct blow molding method or injection molding used for molding plastics is used. Method, injection molding method, extrusion molding method, vacuum molding method, etc.
You may coat.

The material of the container molded by the direct blow molding method, the injection molding method, the injection blow molding method, the extrusion molding method, the vacuum molding method and the like is, for example, polylactic acid, aliphatic polyester, hydroxy polyester, polycaprolactone, poly Examples thereof include amino acids, and these may be used alone or in combination. Additives to these plastics,
For example, it may contain an ultraviolet absorber, a plasticizer, a lubricant, a coloring agent, a crystal nucleating agent, an antistatic agent and the like. As the hydroxy polyester, 3-hydroxybutyrate and 3-hydroxyvalerate copolymer are preferable.

Examples of containers and the like for improving the gas barrier property include containers such as plastic bottles, plastic tanks, plastic tubes, plastic boxes, plastic cases, and plastic bags, as well as plastic sheets, plastic films, and plastics. Panels and the like are also possible.

Next, an experimental example of the resin coating container of the present invention will be described below.

[0046]

[Experimental Example 1] In Experimental Example 1, the glass transition temperature was 56.
3 ° C, crystallization temperature 107.8 ° C, melting point 160.3 °
C, weight average molecular weight / number average molecular weight (Mw / Mn) =
Polylactic acid composed of 2.4 was injection molded at a cylinder temperature of 200 ° C and a mold temperature of 15 ° C, and the diameter of the flange 3 was 3
0mm, diameter of body 4 is 27.4mm, body length 120
mm, 15 g of preform (bottom parison) was obtained.

The preform was subjected to a flame treatment to a wettability of 58 dynes, and 40 g of a hydrochloric acid solution of PH = 2 was added to 8.3 g of tetraethylorthosilicate (Si (OC ₂ H ₅ ) ₄ ) to hydrolyze the solid content. A 5% SiO ₂ solution was obtained. This was mixed with polyvinyl alcohol PVA at a weight ratio of 5% aqueous solution such that SiO ₂ / PVA = 1/1.

This SiO ₂ / PVA coated preform was reheated to 110 ° C. (reheating temperature) and gradually cooled to a uniform preform temperature of 90 ° C. (stretching temperature), and the stretching rod pressure was 7 kgf.・ Cm ^-2 0.5
s, the primary blow 5 Kgf · cm ^-2 3s, secondary blow is stretch blow molded at 15 kgf · cm ^-2 3s, longitudinal stretching ratio 1.3 times, transverse stretching ratio 2.6 times, the bottle height 150
A 300 ml SiO ₂ / PVA coated polylactic acid blow bottle having a diameter of 65 mm and a diameter of 65 mm was obtained.

The blow bottle thus obtained has a transparent appearance, a uniform coating agent, and a wall thickness of 0.6 mm.
It became a container. When this blow bottle was buried in soil for 6 months, the strength of this blow bottle decreased significantly,
There was no force to hold the shape. The plastic bottle left in the air did not change its appearance. The results of measuring the oxygen permeability of this plastic bottle are shown in Table 1.

[0050]

Experimental Example 2 In Experimental Example 2, the same preform as in Experimental Example 1 was used. This preform was subjected to stretch blow molding without coating treatment to obtain a stretch blow container without coating treatment. The blow bottle was subjected to a flame treatment to a wettability of 60 dynes, dipped in an Al ₂ O ₃ / PVA coating agent having 15% Al, and Al ₂ O ₃
A polylactic acid blow bottle coated with / PVA was obtained.
When this blow bottle was buried in the soil for 6 months, the blow bottle had a marked decrease in strength and no ability to retain its shape. There was no change in the appearance of the plastic bottle left in the air. The results of measuring the oxygen permeability of this blow bottle are shown in Table 1.

[0051]

Experimental Example 3 In Experimental Example 3, weight average molecular weight / number average molecular weight (Mw / Mn) = 3, difference between melting temperature and recrystallization temperature = 30.4 ° C. (melting temperature = 93.8 ° C., Recrystallization temperature = 63.4 ° C), heat of fusion = 35.9 J / g Aliphatic polyester consisting of dicarboxylic acid and glycol is injection-molded, 30 mm diameter flange, 28 mm diameter body, 100 mm length A preform (bottom parison) having a thickness of 2.0 mm and a weight of 10 g was obtained.

The preform was frame-treated to have a wettability of 57 dynes, dipped in a PVA coating agent, and
A VA coated preform was obtained.

The PVA-coated preform was reheated to 94 ° C (stretching temperature) and the stretch rod pressure was adjusted to 7
kgf · cm ⁻² 0.5 s, primary blow 3.3 Kgf ·
cm ^-2 2s, secondary blow stretch blow molding at 30Kgf · cm ^-2 5s, longitudinal draw ratio 1.4 times, transverse draw ratio 2.2 times, bottle height 140mm, diameter 62mm 35
0 ml of polyvinyl alcohol coated aliphatic polyester blow bottle was obtained.

The blow bottle thus obtained has a transparent appearance, a uniform coating agent, and a wall thickness of 0.5 mm.
It became a container. When this blow bottle was buried in soil for 6 months, the strength of this blow bottle decreased significantly,
There was no force to hold the shape. The plastic bottle left in the air did not change its appearance. The results of measuring the oxygen permeability of this plastic bottle are shown in Table 1.

[0055]

Experimental Example 4 In Experimental Example 4, 3-hydroxybutyrate 3
A hydroxyvalerate copolymer was used at a cylinder temperature of 140
100m height by injection molding at ° C and mold temperature of 60 ° C
m, a container diameter of 40 mm, and a wall thickness of 0.2 mm were obtained.
Frame processing this cup to a wetness of 54 dynes,
It was immersed in an Al ₂ O ₃ / PVA coating agent containing 30% of Al to obtain an Al ₂ O ₃ / PVA coating cup. The cup thus obtained had a uniform coating layer and a transparent appearance. When this cup was buried in the soil for 6 months, the strength was significantly reduced and there was no ability to retain its shape. There was no change in appearance of the cup left in the air. The results of measuring the oxygen permeability of this cup are shown in Table 1.

[0056]

Experimental Example 5 In Experimental Example 5, 3 hydroxybutyrate 3
A hydroxyvalerate copolymer was used at a cylinder temperature of 140
Direct blow molding at ° C, mold temperature 60 ° C, bottle height 190 mm, bottle diameter 75 mm, capacity 650 m
A blow bottle having a weight of 1, 20 g and a wall thickness of 0.3 mm was obtained.

This blow bottle was subjected to a frame treatment to obtain a wettability of 60 dynes and SiO ₂ containing 60% of silicon Si.
/ PVA coating agent to obtain SiO ₂ / PVA coating blow bottle. This blow bottle 6
When it was buried in the soil for a month, its strength decreased significantly and it had no ability to retain its shape. There was no change in appearance of the cup left in the air. The results of measuring the oxygen permeability of this cup are shown in Table 1.

[0058]

Comparative Example 1 Next, the same preform as in Experimental Example 1 was subjected to stretch blow molding without being subjected to coating treatment to obtain an uncoated stretch blow bottle similar to that in Experimental Example 1. The results of measuring the oxygen permeability of this blow bottle are shown in Table 1.

[0059]

Comparative Example 2 Next, the same preform as in Experimental Example 3 was stretch blow-molded without coating treatment, and an uncoated stretch blow bottle similar to Experimental Example 3 was obtained as Comparative Example 2. Table 1 shows the oxygen permeability results of the blow bottle of Comparative Example 2.

[0060]

Comparative Example 3 A preform similar to that of Comparative Example 2 was stretch-blown without coating treatment, flame-treated to a wetness of 57 dynes, immersed in a PVA coating agent, and subjected to the same initial oxygen permeability as in Experimental Example 1. To obtain a PVA coated blow bottle.

[0061]

Comparative Example 4 Furthermore, in Comparative Example 4, the cup obtained by the injection molding of Experimental Example 4 was used and no coating treatment was performed. Table 1 shows the results of measuring the oxygen permeability of Comparative Example 4.
Shown in

[0062]

Comparative Example 5 As Comparative Example 5, the bottle obtained by the direct blow molding of Experimental Example 5 was used and no coating treatment was performed. The results of measuring the oxygen permeability of this container are shown in Table 1.

[0063]

[Table 1] After 1 month of initial use Bottle material Capacity (l) Coating agent Metal concentration Oxygen permeability Oxygen permeability Experimental example 1 Polylactic acid 0.3 SiO ₂ / PVA 50% 0.3 Experimental example 2 Polylactic acid 0.3 SiO ₂ / PVA 5 0.4 Comparison Example 1 Polylactic acid 0.3 0.8 Experimental Example 3 Aliphatic Polyester 0.3 PVA 0 0.6 0.6 Comparative Example 2 Aliphatic Polyester 0.35 1.1 Comparative Example 3 Aliphatic Polyester 0.35 PVA 0 0.6 0.9 Experimental Example 4 Human Oxypolyester 0.4 Al ₂ O ₃ / PVA 30 0.5 Comparative Example 4 Human Epoxy Polyester 0.4 1.2 Experimental Example 5 Human Epoxy Polyester 0.65 SiO ₂ / PVA 60 0.7 Comparative Example 5 Human Epoxy Polyester 0.65 1.8 (Oxygen permeability is in ml / pkg · day, oxygen permeability is 40 ° C after 1 month Humidity The container of this example is a biodegradable plastic that is decomposed by microorganisms, and the surface of the biodegradable plastic is shown. Since the resin coating of the coating agent is formed on the
The gas barrier property is improved, and even if it is left on the ground or scattered, it is prevented from biodegrading and polluting the environment. Particularly, when a preform coated with a coating agent is stretched to form a container, not only the preform but also the resin coating film of the coating agent is stretched, so that the molecular gap of the resin is narrowed and the gas barrier is crystallized. The properties of gas molecules are close to each other and the oxygen barrier property, carbon dioxide barrier property,
Gas barrier properties such as odor barrier properties are improved. When the alkoxide or the alkoxide hydrolyzate is contained in the crystal, the gas barrier property is further improved due to the good gas barrier property of the metal. Further, according to the method of manufacturing the preform 1 and the blow bottle of the present embodiment, the preform 1 coated with the resin film having the gas barrier property in advance is stretch-blown. By comparison, it is possible to obtain a container having a sufficient gas barrier property in spite of a short manufacturing time and a low manufacturing cost.

[0064]

According to the container of claims 1 and 2, the container is made of biodegradable plastic such as polylactic acid or fatty acid polyester, and the surface thereof is coated with a polyvinyl alcohol-based coating agent. Since it forms a resin film by being formed, the gas barrier property is improved, and when it is left outdoors after use and gets wet with water drops, it swells and elutes, and is eventually biodegraded.

According to the container of claim 3 of the present invention, in addition to the function of the container of claims 1 and 2, the metal alkoxide or the metal alkoxide hydrolyzate is contained in the resin coating in the range of 5% by weight to 70% by weight. Since it is included, the gas barrier property is further improved compared to the case where it is not included.

According to the preform of claim 4 of the present invention, in addition to the function of the container of claims 1 and 2, when the preform is set in a mold and stretch blow molded, the biodegradable plastic is stretched. As the container is formed, the coating agent on the surface is stretched and oriented, and the gap between the resins is narrowed and crystallized, so that the gas barrier property is improved. Moreover, according to the preform of the fifth aspect, since the metal alkoxide or the metal alkoxide hydrolyzate is contained, the gas barrier property is further improved.

According to the method for producing a container of claim 6 of the present invention, the time and effort required for producing the container are short, the production time is short as compared with the laminating method, and the production cost is low. It is possible to obtain a container having the above-mentioned property, and furthermore, even if it is scattered and left outside after use, it biodegrades and disappears, thus preventing environmental pollution.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an uncoated preform according to an embodiment of the present invention.

FIG. 2 is an explanatory view of a state in which activation processing of the preform surface of FIG. 1 is performed.

FIG. 3 is an explanatory diagram showing a state of immersion of a preform in a coating agent after activation treatment.

FIG. 4 is a cross-sectional view of a state in which a preform after forming a resin film with a coating agent is stretch-blown.

FIG. 5 is a cross-sectional view of the coated preform of this example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Preform 2 Screw part 3 Flange part 4 Body part 5 Coating agent 6 Liquid tank 7 Plastic bottle 8 Resin coating 8'Stretched resin coating 9 Mold 10 Mold 11 Stretching rod

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location B29K 77:00 B29L 9:00 (72) Inventor Kazuya Hachibo 1-5 Taito, Taito-ku, Tokyo No. 1 Toppan Printing Co., Ltd.

Claims (6)

[Claims] 1. A container characterized in that a resin film containing a polyvinyl alcohol-based coating agent is formed on the surface of a container made of biodegradable plastic. 2. The container according to claim 1, wherein the biodegradable plastic bottle is a simple substance or a complex of any one of polylactic acid, aliphatic polyester, hydroxypolyester, polycaprolactone, or polyamino acid. A container characterized by. 3. The container according to claim 1, wherein the resin coating contains 5 wt% to 70 wt% of a metal alkoxide or a hydrolyzate of the metal alkoxide, and the metal of the metal alkoxide is silicon or aluminum. A container characterized by being any of the following. 4. A preform for molding the container according to any one of claims 1 to 3, wherein the material is at least polylactic acid, aliphatic polyester, hydroxypolyester, polycaprolactone, or polyamino acid. A preform having a resin coating formed of a polyvinyl alcohol-based coating agent on the surface. 5. The preform according to claim 4, wherein the resin coating contains 5 wt% to 70 wt% of either a metal alkoxide or a metal alkoxide hydrolyzate, and the metal of the metal alkoxide is silicon or aluminum. A preform characterized by being one of: 6. A method of manufacturing a container for forming the container according to any one of claims 1 to 3, which comprises a polylactic acid, an aliphatic polyester, a hydroxy polyester, a polycaprolactone, or a polyamino acid. After activating the surface of the preform, at least the polyvinyl alcohol-based coating agent is coated on the surface of the preform, and the preform is heated and then disposed in the cavity of the mold for stretch blow molding. And a method of manufacturing a container.