JP2003071943A - Oxygen barrier resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin molding which has excellent oxygen barrier properties even under a high humidity condition without necessity of a heat treatment for a long time like prior art and which has a good appearance even after retort-treating. SOLUTION: A method for manufacturing the resin molding comprises the steps of irradiating the molding made of a resin composition containing a high hydrogen-bonding resin with a radioactive ray, and adding a heat to the molding in a range of 100 to 300 deg.C. The resin molding is manufactured by this method. A laminate has at least one layer of the resin molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molded product such as a film, sheet or bottle having an excellent oxygen barrier property and a method for producing the same.

[0002]

2. Description of the Related Art Polyolefin films, nylon films, polyethylene terephthalate (PE) have hitherto been used for materials such as food packaging materials which are required to have an oxygen gas barrier property.
T) Films in which vinylidene chloride latex is coated have been widely used.

However, there is a risk of generation of chlorine gas and dioxins due to chlorine in polyvinylidene chloride at the time of incineration during waste treatment.
It has a problem that it can cause a great adverse effect on the environment and the human body. As an oxygen gas barrier material that does not contain chlorine, polyvinyl alcohol (PV
A) Films are the best known. The PVA film has the characteristic that the oxygen gas barrier property is the best among the synthetic resin films in the dry state, but the oxygen gas barrier property has a large humidity dependency, and under high humidity conditions, this gas barrier property is absorbed due to moisture absorption. It has a problem of being greatly damaged. Further, the PVA film is also a film made of saccharides such as starch, which is easily dissolved in boiling water, poly (meth) acrylic acid, and polyacrylamide, although the oxygen gas barrier property is good in a dry state like PVA, Under high humidity conditions, the oxygen gas barrier property is greatly reduced by moisture absorption. Various studies have been made to solve the problems of the PVA film and the like. For example, multi-layering of PVA film and other hydrophobic film,
Biaxial stretching, heat treatment, copolymerization with ethylene and the like can be mentioned. By using these methods, the water resistance and the oxygen gas barrier property under high humidity are improved, but the degree of the improvement is insufficient.

Further, studies have been made to solve the problems of the PVA film by introducing a crosslinked structure into PVA. However, generally, the oxygen gas barrier property of the PVA film under high humidity is improved with an increase in the crosslink density, but the oxygen gas barrier property under the dry condition originally possessed by the PVA film is reduced accordingly. As a result, it is very difficult to obtain a good oxygen gas barrier property under high humidity. By forming a film from a mixed solution of PVA, saccharides, etc. and poly (meth) acrylic acid, and then heat-treating it, a hydroxyl group of PVA, saccharides etc. and a carboxylic acid of poly (meth) acrylic acid are reacted to form a crosslinked structure. It has been proposed that a film excellent in oxygen gas barrier property under high humidity can be obtained by forming the film (JP-A-10-237180). However, this method requires heat treatment for a long time or heat treatment at a high temperature, and a large amount of energy is required at the time of manufacturing, so that the load on the environment is not small. Further, if the heat treatment temperature is high, there is a risk of discoloration or decomposition of PVA,
When a film is formed on a support such as a plastic film, the support film is deformed such as wrinkles and is not suitable for use as a packaging material. On the other hand, if the heat treatment temperature is low, a very long heat treatment time is required,
There is a problem that productivity is reduced.

On the other hand, as a method for obtaining a film having a low energy and an excellent oxygen gas barrier property, there is a method in which an aqueous PVA solution is coated on the film, dried and irradiated with radiation (Japanese Patent Laid-Open No. 10-1089). . However, in this method, since the crosslinked structure is insufficient, the oxygen gas barrier property under dry conditions is excellent, but the oxygen gas barrier property under high humidity conditions is improved, but it is still insufficient. Furthermore, since the obtained crosslinked structure is insufficient, when the retort treatment is performed, the barrier layer melts,
There is a problem that it cannot be used for packaging retort foods due to whitening and wrinkles.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to perform retort treatment by having excellent oxygen gas barrier properties even under high humidity conditions without requiring heat treatment for a long time as in the conventional case. Another object is to provide a resin molded product having a good appearance.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a resin composition containing a high hydrogen-bonding resin is
By performing two treatments, radiation treatment and heat treatment,
It has been found that a desired resin molded product can be obtained.

That is, the present invention is characterized in that a molded product made of a resin composition containing a high hydrogen bonding resin is subjected to a treatment of irradiating with radiation and a treatment of applying heat in the range of 100 to 300 ° C. And a method for manufacturing a resin molded product.

The present invention also relates to a resin molded product manufactured by the above manufacturing method.

The present invention also relates to a laminate having at least one layer of the above resin molded product.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The high hydrogen-bonding resin referred to in the present invention is a resin having a hydrogen-bonding group or an ionic group resin, and the hydrogen-bonding group and the ionic group are contained in the whole resin. It satisfies the ratio of 10% by weight to 70% by weight.

As the hydrogen-bonding group, a hydroxyl group, an amino group,
Examples thereof include an amide group, a thiol group, a carboxyl group, a sulfonic acid group, and a phosphoric acid group, and examples of the ionic group include a carboxylate group, a sulfonate ion group, a phosphate ion group, an ammonium group, and a phosphonium group.

Specifically, for example, polyvinyl alcohol, an ethylene-vinyl alcohol copolymer having a vinyl alcohol fraction of 41 mol% or more, hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, amylose, amylopectin, pullulan,
Polysaccharides such as curdlan, xanthan, chitin, chitosan, cellulose, pullulan, chitosan, polyacrylic acid, sodium polyacrylate, polybenzenesulfonic acid, sodium polybenzenesulfonate, polyacrylamide, polyethyleneimine, polyallylamine,
The ammonium salt, polyvinyl thiol, polyglycerin, etc. are mentioned.

Polyvinyl alcohol is obtained by hydrolyzing (saponifying) the acetic ester portion of a vinyl acetate polymer, and more precisely, it is a copolymer of vinyl alcohol and vinyl acetate. Here, the percentage of saponification is preferably 85% or more, more preferably 95% or more, in terms of molar percentage. The degree of polymerization is 50 to 500.
0 is the preferred range.

Monomers may be added to the composition in order to form a resin molded product together with the above high hydrogen bond resin.
Examples of the monomer that can be used include known monomers such as acrylate that can be polymerized by irradiation with radiation.

Specifically, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate,
Butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, phenoxyethyl (meth) acrylate, lauryl (meth) acrylate, ethoxyethyl (meth) acrylate, methoxymethyl (meth) acrylate, N, N-diethylaminoethyl ( (Meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, glycidyl (meth) acrylate, allyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-methoxyethoxy Ethyl (meth) acrylate, 2-ethoxyethoxyethyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth)
Acrylate, 2-hydroxycyclopentadienyl (meth) acrylate, dicyclopentadiene ethoxy (meth) acrylate, acryloylmorpholine,
1,3-butanediol di (meth) acrylate, 1,
4-butanediol di (meth) acrylate, 1,6-
Hexanediol di (meth) acrylate, polyethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, Hydroxypivaphosphate neopentyl glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, 3-methylpentanediol di (meth) acrylate, methylenebisacrylamide, bis (acryloxyethoxy) bisphenol A, bis (acryloxyethoxy) ) Tetrabromobisphenol A, bis (acryloxypolyethoxy) bisphenol A, 1,3-bis (hydroxyethyl) -5,5-dime Ruhindatoin, N- vinylpyrrolidone, (meth) acrylamide, (meth) acrylonitrile.

The resin composition and the molded product of the present invention may contain a known photopolymerization initiator (sensitizer) within a range not impairing the effects of the present invention. Specifically, benzoin, benzoin methyl ether, benzoin ethyl ether,
Benzoin and its alkyl ethers such as benzoin isopropyl ether, acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 4- (1-t-butyldioxy-1-)
Acetophenones such as methylethyl) acetophenone,
Anthraquinones such as 2-methylanthraquinone, 2-amylanthraquinone, 2-t-butylanthraquinone, and 1-chloroanthraquinone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone,
Thioxanthones such as 2-chlorothioxanthone, ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal, phenyl ketones such as 1-hydroxycyclohexyl phenyl ketone, benzophenone, 4
Benzophenones such as-(1-t-butyldioxy-1-methylethyl) benzophenone and 3,3 ', 4,4'-tetrakis (t-butyldioxycarbonyl) benzophenone, 2-methyl-1- [4- ( Methylthio) phenyl] -2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, acylphosphine oxides, xanthones and the like. It can be used as a kind or a mixture of two kinds or more. Further, an inorganic layered compound may be added to the resin composition and the molded product of the present invention. Specific examples include vermiculite, montmorillonite, hectorite, tetrasilylic mica, muscovite and phlogopite. Further, a solvent may be added to the above resin composition in order to improve coatability. As the solvent, a high hydrogen bond resin or a solvent capable of dissolving other monomers or photopolymerization initiators used as necessary,
It can be used without particular limitation, such as methanol, ethanol,
Alcohols such as 2-propanol, butanol and ethylene glycol, cellosolves such as cellosolve and butyl cellosolve, carbitols such as carbitol and butyl carbitol, esters such as cellosolve acetate and carbitol acetate, acetone, methyl isobutyl ketone, Examples thereof include ketones such as methyl ethyl ketone, ethers such as diethylene glycol dimethyl ether, and the like.

The form of the molded article referred to in the present invention is a film,
Not only sheets, but also molded products such as containers in various forms such as bottles are included.

Further, the laminate referred to in the present invention is a laminate in which two or more layers are formed, and the films made of a resin composition containing a high hydrogen-bonding resin are stuck together,
Examples include those obtained by coating a support with a resin composition containing a high hydrogen-bonding resin, and multilayer structures thereof. Examples of the support include polyethylene terephthalate,
Examples include films made of polyester resins such as polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate, films made of polyamide resins such as nylon 6, nylon 66, nylon 46, and films made of polyolefin resins such as polyethylene and polypropylene. .

Known techniques can be applied to the laminating and coating. Specifically, multi-layer laminate molding method, co-extrusion molding method, blow molding method, discharge from casting head, roll coat, air knife coat, gravure roll coat, doctor roll coat, doctor knife coat, curtain flow coat, spray, wire bar,
Examples include rod coating and dipping. At this time, the coating film is formed to have a thickness of 0.5 to 200 μm. When the coating thickness is out of this range, it is difficult to obtain a coating having a uniform thickness, which is not preferable.

The type of radiation used in the present invention is not particularly limited, and examples thereof include α-ray, β-ray, γ-ray and electron beam. In particular, electron beams are more preferable from the viewpoint of production efficiency and safety. As a radiation device, an acceleration voltage of 20 to 2000
Examples include electron beam accelerators taken out from kV accelerators, xenon lamps, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, and ultra-high-pressure mercury lamps. The heat treatment apparatus is not particularly limited, and heat treatment method in a dry heat atmosphere such as an oven, heat roll contact, heat medium contact (air, oil, etc.), infrared heating,
Various things such as microwave heating can be applied. The heat treatment temperature is preferably in the range of 100 to 300 ° C, particularly 12
The range of 0-250 degreeC is more preferable. If the temperature is lower than 100 ° C., the crosslinking reaction is insufficient, so that it is difficult to obtain a sufficient oxygen gas barrier property under high humidity conditions. Even if the heat treatment is carried out for a long time, it is not preferable because the production efficiency is lowered. On the other hand, if the temperature exceeds 300 ° C., wrinkles, deformation, and thermal decomposition occur in the support and the resin composition, and the oxygen gas barrier property and the mechanical properties deteriorate, which is not preferable. The irradiation conditions of the radiation used in the present invention are not particularly limited,
Various conditions are possible. The irradiation atmosphere is preferably an inert gas atmosphere such as under nitrogen, but there is no particular problem even in air. Further, the irradiation speed and irradiation time are not particularly limited as long as a predetermined absorbed dose is irradiated. Either the radiation treatment or the heat treatment may be performed first, or may be performed simultaneously.

[0022]

EXAMPLES The present invention will be described in detail below with reference to examples. Unless otherwise specified,% means% by weight and part means part by weight. <Oxygen permeability> After each film was left in an atmosphere of 25 ° C. and 80% RH for 3 weeks, the Modern Control was carried out.
The oxygen permeability at 25 ° C. and 80% RH was determined using an oxygen permeability tester OX-TRAN TWIN manufactured by the company.
Specifically, oxygen gas and nitrogen gas (carrier gas) humidified at 25 ° C. and 80% RH were used. The oxygen permeability of the film formed from the mixture containing the oxygen gas barrier layer was calculated by the following formula. 1 / P _total = 1 / P _film + 1 / P _PET where P _total : oxygen of a laminated film composed of a film layer formed from a composition containing an oxygen gas barrier layer and a support film (polyethylene terephthalate film) layer Permeability P _film : Oxygen permeability of a film layer formed from a composition containing an oxygen gas barrier layer P _PET : Oxygen permeability of a support film (polyethylene terephthalate film) layer [Example 1] Wako Pure as polyacrylic acid An aqueous solution was prepared using polyacrylic acid (number average molecular weight: about 25,000) manufactured by Yakuhin Kogyo Co., Ltd. Further, polyvinyl alcohol (saponification degree: 96% or more, average polymerization degree: about 500) manufactured by Wako Pure Chemical Industries, Ltd. was used as PVA, and dissolved in hot water and then cooled to room temperature to obtain an aqueous solution of PVA. Mixing the polyacrylic acid aqueous solution and the PVA aqueous solution so that the carboxylic acid and the hydroxyl unit have a molar ratio as shown in Table 1,
Further, 10 parts by weight of sodium hypophosphite monohydrate manufactured by Wako Pure Chemical Industries, Ltd. as a reaction catalyst was added to 100 parts by weight of PVA and polyacrylic acid in total to prepare an aqueous solution having a solid content of 15% by weight. Two types were adjusted.

The obtained aqueous solution was applied onto a stretched polyethylene terephthalate film (stretched PET film having a thickness of 25 μm) using a bar coater, and this film was accelerated using an electron beam irradiation device manufactured by Nisshin High Voltage Co., Ltd. Voltage 175kV, current 16.7mA, conveyor speed 1
Electron beam irradiation was performed once under a nitrogen atmosphere at 5 m / min (absorption dose 100 kGy). Then, in an electric oven,
By performing the drying and heat treatment as shown in, a film having a thickness of 5 μm was formed to obtain a laminated film. The obtained laminated film and the stretched PET film of the support, each at 25 ° C.,
The P _film value was determined from the measurement results of oxygen permeability at 80% RH. The results are shown in Table 1. Moreover, the obtained laminated film was immersed in hot water at 80 ° C. for 10 minutes to evaluate the surface condition of the laminated body. The results are shown in Table 1.

[0024]

[Table 1]

Evaluation of hot water treatment 5 (excellent) -1 (inferior) [Example 2] The same as Example 1 except that acryloylmorpholine was used.
Similar method except that 3 parts by weight of (ACMO) was added.
I got a film with. Of the obtained laminated film and support
Stretched PET film, at 25 ° C and 80% RH respectively
From the measurement result of oxygen permeability of P _filmThe value was calculated. That conclusion
The results are shown in Table 2. In addition, the obtained laminated film is 80
The surface condition of the laminate was evaluated by immersing it in hot water at ℃ for 10 minutes.
It was The results are shown in Table 2.

[0026]

[Table 2]

Evaluation of Hot Water Treatment 5 (Excellent) -1 (Poor) [Comparative Example 1] A film was obtained in the same manner as in Example 1 except that the electron beam irradiation was not performed. The obtained laminated film and the stretched PET film of the support, each 25
The P _film value was obtained from the measurement results of oxygen permeability at 80 ° C. and 80% RH. The results are shown in Table 3. Moreover, the obtained laminated film was immersed in hot water at 80 ° C. for 10 minutes to evaluate the surface condition of the laminated body. The results are shown in Table 3.

[0028]

[Table 3]

Evaluation of Hot Water Treatment 5 (Excellent) -1 (Poor) [Comparative Example 2] A film was obtained in the same manner as in Example 1 except that heating was not performed. The obtained laminated film and the stretched PET film of the support, respectively, 25 ° C., 80
The P _film value was obtained from the measurement result of the oxygen permeability in% RH. The results are shown in Table 4. Moreover, the obtained laminated film was immersed in hot water at 80 ° C. for 10 minutes to evaluate the surface condition of the laminated body. The results are shown in Table 4.

[0030]

[Table 4]

Evaluation of hot water treatment 5 (excellent) -1 (inferior) [Comparative Example 3] As PVA, polyvinyl alcohol manufactured by Wako Pure Chemical Industries, Ltd. (saponification degree: 96% or more, average polymerization degree: about 500) was used. An aqueous solution of PVA was obtained by dissolving it in hot water and then cooling to room temperature to prepare an aqueous solution having a solid content of 15% by weight.

The obtained aqueous solution was coated on a stretched polyethylene terephthalate film (stretched PET film having a thickness of 25 μm) using a bar coater, and this film was accelerated using an electron beam irradiation device manufactured by Nisshin High Voltage Co., Ltd. Voltage 175kV, current 16.7mA, conveyor speed 1
Electron beam irradiation was performed once under a nitrogen atmosphere at 5 m / min (absorption dose 100 kGy). Then, in an electric oven, Table 5
By performing the drying and heat treatment as shown in, a film having a thickness of 5 μm was formed to obtain a laminated film. The obtained laminated film and the stretched PET film of the support, each at 25 ° C.,
The P _film value was determined from the measurement results of oxygen permeability at 80% RH. The results are shown in Table 5. Moreover, the obtained laminated film was immersed in hot water at 80 ° C. for 10 minutes to evaluate the surface condition of the laminated body. The results are shown in Table 5.

[0033]

[Table 5]

Hot water treatment evaluation 5 (excellent) -1 (inferior)

[0035]

Industrial Applicability According to the present invention, it is possible to provide a resin molded product having low energy, high production efficiency, and excellent oxygen gas barrier property even under high humidity conditions.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B29K 67:00 B29K 67:00 C08L 101: 02 C08L 101: 02 F term (reference) 4F073 AA17 BA03 BA17 BA18 BA34 BB01 BB03 CA41 CA42 CA45 GA01 4F100 AK01A AK01B AK21B AK25B AK42A BA02 BA10A BA10B BA15 CC00B EH462 EJ38A EJ422 EJ532 GB23 JA20B 4F201 AA19 BR02 BC06 BA07 BR02 BR12 BA07 BC02 BR02 BA06 BA02 BR02 BA06

Claims (3)

[Claims] 1. A process of irradiating a molded product made of a resin composition containing a high hydrogen-bonding resin with radiation, and 100 to 3
A method for producing a resin molded product, which comprises performing heat treatment in the range of 00 ° C. 2. A resin molded product manufactured by the manufacturing method according to claim 1. 3. At least one resin molded product according to claim 2.
A laminate having layers.