JP4997865B2 - Gas barrier rubber-like molded body and method for producing the same - Google Patents

Description

  The present invention relates to a rubber-like molded article having good gas barrier properties and a method for producing the same.

  It is well known that a laminated film formed by forming a resin layer containing a polyvalent metal cross-linked product of polycarboxylic acid on a resin film substrate has good gas barrier properties. In general, such a gas barrier film contains a polycarboxylic acid and a polyvalent metal compound on a film substrate, and further, an agent that relaxes the crosslinking (gelation) reaction between them, such as ammonia or amine, metal alkoxide (or An aqueous coating composition containing the hydrolyzed (condensed product) is applied, and then a crosslinking reaction between the polycarboxylic acid and the polyvalent metal compound is promoted by heating or the like to form a gas barrier layer containing the metal crosslinked product. (For example, Patent Documents 1 to 3. Many others). In addition, in order to prevent premature gelation reaction between polycarboxylic acid and polyvalent metal compound, polycarboxylic acid layer and polyvalent metal compound layer are applied so as to be adjacent to each other, and then in the vicinity of the interface between both layers by cross-linking or the like It is also known to form a gas barrier layer containing a metal cross-linked resin (Patent Document 1). Further, a coating film of an aqueous solution or dispersion of an α, β-unsaturated carboxylic acid neutralized with a polyvalent metal or a partially neutralized α, β-unsaturated carboxylic acid is formed on the film substrate. A method for producing a gas barrier laminate film having a gas barrier layer formed by polymerizing this is also known (Patent Documents 4 and 5).

The laminated film product thus formed is considered useful as a packaging material that generally requires gas barrier properties (Patent Documents 1 to 5). However, the product development to the gas-barrier rubber-like molded body which is more flexible and deformable has not been made.
WO03 / 0931317A1 publication JP 2005-60621 A WO2005 / 053954A1 publication WO2005 / 108440A1 publication WO 2006/059773 A1

  The main object of the present invention is to provide a gas barrier rubber-like molding in which a gas barrier layer comprising a neutralized or non-neutralized α, β-unsaturated carboxylic acid polymer layer is formed on a flexible and deformable rubber substrate. To provide a body.

That is, the gas barrier rubber-like molded article of the present invention includes a rubber base material having a certain thickness, and a gas barrier layer laminated on at least one of the two surfaces sandwiching the thickness of the rubber base material, α gas barrier layer has a polyvalent metal by a chemical equivalent basis with 0% to 90% neutralized carboxyl groups, beta-Ri Do from the spot polymer layer of an unsaturated carboxylic acid, and and stretched 10% in one axial direction In this state, after holding for 1 minute, the gas barrier layer does not peel off in a state where the tensile force is released, and the oxygen permeability is the same as that before the tensile stretching .

  A few additional notes about how the present inventors arrived at the present invention.

  As described above, a gas barrier laminate film in which a gas barrier resin layer containing a polycarboxylic acid polyvalent metal crosslinked product is formed on a resin film substrate is well known. However, no gas barrier rubber-like molded article using a rubber substrate instead of a resin film substrate has been developed. The reason is not necessarily clear, but it is understood that the following factors are acting. (A) The biggest factor is that the rubber base material has significantly greater flexibility and stretch deformability than the resin film base material. From the polycarboxylic acid polyvalent metal crosslinked product formed thereon, It is understood that this gas barrier layer cannot follow the elastic deformation of the rubber base material and loses the gas barrier layer. In fact, a 12 μm thick PET (polyethylene terephthalate) film, which is a typical resin film substrate, has a tensile modulus (JIS K7100) of 4000 MPa, whereas the thickness used as a rubber substrate in Example 1 described later. That of the 500 μm nitrile rubber sheet was only 6 MPa. Therefore, in Tables 5 and 6 of Patent Document 4, the surface state evaluation results after stretching 2% and 3% of the obtained gas barrier laminate film are described, but in many laminate films, after stretching 3% In No. 1, the deterioration of the surface state is recorded as compared with after 2% stretching, and the evaluation of gas barrier properties after stretching is not performed. Moreover, evaluation at a draw ratio exceeding 3% has not been made. (B) The second reason is that the surface roughness Ra of the rubber substrate (JIS B0601; for example, Ra = 2.0 μm in the nitrile rubber sheet of Example 1) is that of the resin film substrate (for example, for PET film, (Ra = 0.02 μm). As shown in Examples of Patent Documents 1 to 5, this is considered to be considered not to be a base material suitable for forming a dense gas barrier layer having a thickness of about 0.1 to 1 μm on the surface. .

  On the other hand, according to the study of the present inventors, the gas barrier layer composed of an in-situ polymer layer on the rubber base material of α, β-unsaturated carboxylic acid with suppressed neutralization degree by polyvalent metal No good whitening afterwards, and 10% stretched and held for 1 minute-after release-good adhesion represented by no loss of gas barrier layer adhesion and no substantial change in gas barrier properties It was found to exhibit stretch deformation followability (see the results of the stretch followability evaluation test of the gas barrier layer (polymer layer) in the gas barrier rubber-like molded products of Examples 3 and 6 below). This is because the in-situ polymerization process of α, β-unsaturated carboxylic acid having a suppressed degree of neutralization on the rubber base material improves the adhesion of the obtained polymer to the base material. It is considered that the anchoring effect due to the surface roughness of the material contributes to the improvement of the followability to the elastic deformation of the rubber base material. The gas barrier rubber-like molded product and the method for producing the same according to the present invention are based on the above knowledge.

  Hereinafter, the gas barrier rubber-like molded product of the present invention will be sequentially described along with the production method thereof.

(Rubber base material)
The rubber base material used in the present invention is made of an arbitrary rubber material having stretch deformability according to the use of the rubber-like molded body to be formed. The required properties may vary depending on the application, but as a typical example, for example, the tensile modulus (JIS K7100) is 0.1 to 1000 MPa, preferably 1 to 100 MPa; surface average roughness Ra as a substrate (JIS B0601) Is 0.01 to 100 μm, preferably 0.02 to 10 μm. The elongation at break may be up to about 120% as a required characteristic in relation to the application, but it may be about 100% to 250% of normal. Such characteristics are usually satisfied by a general rubber material, and a known rubber material can be used. Specific examples thereof include natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, acrylonitrile-butadiene rubber, butyl rubber, ethylene-propylene rubber, chlorobrene rubber, acrylic rubber, chlorosulfonated polyethylene rubber, hydrin rubber, urethane rubber, Examples thereof include at least one selected from the group consisting of polysulfide rubber, silicone rubber, and fluororubber.

  The shape of the rubber base material is determined substantially corresponding to the shape of the product rubber-like molded product that requires gas barrier properties, and is not particularly limited. For example, a sheet, tire, tube or cup, tank, etc. Or a precursor thereof (for example, a half or a sheet-like semi-product for giving these shapes by bonding or sheet molding). Further, the rubber base material has a thickness in a direction in which the gas barrier property required for the molded product is to be expressed, and the thickness is generally about 10 μm to 50 mm, preferably about 100 μm to 10 mm.

(Polymerizable monomer composition)
The α, β-unsaturated carboxylic acid neutralized by 0 to 90% with respect to the chemical equivalent on the basis of the chemical equivalent is zero on the basis of the total amount of the composition on at least one of the two surfaces sandwiching the thickness of the rubber substrate. A film of a polymerizable monomer composition formed by dissolving or dispersing in ˜85 wt% solvent is formed.

<Α, β-unsaturated carboxylic acid>
The α, β-unsaturated carboxylic acid constituting the polymerizable monomer composition used in the present invention is a polycarboxylic acid metal crosslinked product used for forming a gas barrier layer in Patent Documents 1-5. Specific examples of the polycarboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, senecioic acid, tiglic acid, sorbic acid, maleic acid. , Fumaric acid, itaconic acid, citraconic acid, mesaconic acid, maleic anhydride, itaconic anhydride, and at least one selected from the group consisting of citraconic anhydride. Of these, acrylic acid and / or methacrylic acid are preferable, and acrylic acid is particularly preferable in view of characteristics such as handling property and gas barrier property and cost.

  As these α, β-unsaturated carboxylic acids, those neutralized by 0 to 90% on a chemical equivalent basis with polyvalent metals described later (partially neutralized) are used. That is, α, β-unsaturated carboxylic acid that is not neutralized can be used as it is. The polymer layer of α, β-unsaturated carboxylic acid that is not neutralized in this way (Example 1 below) is formed of neutralized α, β-unsaturated carboxylic acid under dry conditions (relative humidity 0%). It exhibits a gas barrier property comparable to that of the polymer layer, and is sufficiently useful depending on the use of the product rubber-like molded product. However, in a humid atmosphere (relative humidity of 40% or more), it is difficult to avoid a decrease in gas barrier properties. Therefore, it is preferable to use α, β-unsaturated carboxylic acid partially neutralized with a polyvalent metal for the production of a rubber-like molded product used in applications requiring gas barrier properties in a humid atmosphere. is there. As a specific example, it is preferable to use an α, β-unsaturated carboxylic acid neutralized with a polyvalent metal at a chemical equivalent basis of 10 to 90%, particularly 45 to 75%, and thereby a gas barrier layer having good water resistance. Is formed. This is almost the same as that used in Patent Document 5. However, if a completely neutralized product (100% neutralized product) of α, β-unsaturated carboxylic acid with a polyvalent metal is used, the polymer layer formed on the rubber substrate is whitened, and the desired gas barrier property is obtained. Since it is not obtained, it should be avoided. For polymer layers of α, β-unsaturated carboxylic acids that are not neutralized or have a low degree of neutralization (for example, a degree of neutralization of 45% or less), divalent metal ions and trivalent metal ions are used after polymerization. Gas barrier properties and water resistance may be improved by applying at least one metal ion selected from the group consisting of:

<Multivalent metal>
The polyvalent metal that gives the partially neutralized product of the α, β-unsaturated carboxylic acid described above is a divalent or higher metal. Preferably, it is at least one metal selected from the group consisting of divalent metals and trivalent metals, and these metals dissociate ions in acidic water to give divalent or trivalent metal ions corresponding to the valence. Is.

  Specific examples of the polyvalent metal include metals of Group 2A of the periodic table such as beryllium, magnesium and calcium; transition metals such as titanium, zirconium, chromium, manganese, iron, cobalt, nickel, copper and zinc; and aluminum. Although it can, it is not limited to these. Among these, zinc, calcium, copper, magnesium, aluminum, and iron are preferable. The partially neutralized product of α, β-unsaturated carboxylic acid with a polyvalent metal has different solubility in water depending on the type of metal, but zinc, calcium and magnesium are particularly preferable as the metal species from the viewpoint of solubility.

  The α, β-unsaturated carboxylic acid partially neutralized with the above polyvalent metal may be formed in the polymerizable monomer composition coated on the rubber substrate. -An unsaturated carboxylic acid and a polyvalent metal salt of an α, β-unsaturated carboxylic acid or other polyvalent metal compound may be mixed. Examples of the polyvalent metal compound other than the polyvalent metal salt of α, β-unsaturated carboxylic acid include polyvalent metal oxides, hydroxides, carbonates, and organic acid salts. As the polyvalent metal oxide, zinc oxide, magnesium oxide, and iron (III) oxide are preferable.

  Examples of organic acid salts include acetate, oxalate, citrate, lactate, phosphate, phosphite, hypophosphite, stearate, α, β-monoethylenically unsaturated Examples include, but are not limited to, carboxylates. Examples of the α, β-monoethylenically unsaturated carboxylate include zinc diacrylate, calcium diacrylate, magnesium diacrylate, copper diacrylate, and aluminum acrylate.

  Examples of inorganic acid salts include, but are not limited to, chlorides, sulfates, and nitrates. Alkyl alkoxides of polyvalent metals can also be used as polyvalent metal compounds.

<Solvent>
The polymerizable monomer composition used in the present invention is an α, β-unsaturated carboxylic acid neutralized with 0 to 90% with the above-described polyvalent metal or a precursor thereof in an amount of 0 to 85% based on the total amount of the composition. % By dissolving or dispersing in a solvent. For example, α, β-unsaturated carboxylic acid which is liquid at room temperature such as acrylic acid or methacrylic acid gives a polymerizable monomer composition which can be applied without using a solvent (Example 1 described later).

  As the solvent, it is preferable to use at least one solvent selected from the group consisting of water, alcohol, NMP, THF, and acetone. Among these, water is most preferably used from the viewpoint of application of the polymerizable monomer composition and environmental hygiene during polymerization. The α, β-unsaturated carboxylic acid neutralized by 0 to 90% with a polyvalent metal used in the present invention is a polymerizable monomer composition obtained using such most preferable water as a solvent. A good gas barrier layer is obtained without whitening even by in-situ polymerization.

  The lower limit of the amount of solvent to be used is determined by the suitability for application of the resulting polymerizable monomer composition, and the upper limit is such as the appearance and solvent removal efficiency associated with the degree of neutralization of the resulting polymerizable monomer composition coating film. Determined by Use of a solvent in excess of 85% by weight is not preferable because productivity and film formability may be deteriorated.

<Polymerization initiator>
The polymerizable monomer composition used to form the in-situ polymer layer includes an α, β-unsaturated carboxylic acid neutralized with 0 to 90% with the polyvalent metal or a precursor thereof and a solvent. In addition, a polymerization initiator may be contained. However, when the in-situ polymerization is advanced by irradiation with ionizing radiation having strong energy such as an electron beam, it can be omitted. As the polymerization initiator, a photopolymerization initiator and a thermal polymerization initiator are representative, and at least one polymerization initiator can be contained. Thermal polymerization initiators also include azo compounds and peroxides that are activated by irradiation with ionizing radiation.

  When irradiating a coating film with ultraviolet rays, it is preferable to contain a photopolymerization initiator in the polymerizable monomer composition. Photoinitiators are sometimes simply referred to as photoinitiators or sensitizers. Examples of the photopolymerization initiator include acetophenones, benzophenones, Michler ketones, benzyls, benzoins, benzoin ethers, benzyl dimethyl ketals, thioxanthones, and mixtures of two or more thereof.

  Preferred specific examples of the photopolymerization initiator include acetophenones such as acetophenone, 2,2-diethoxyacetophenone, m-chloroacetophenone, p-tert-butyltrichloroacetophenone and 4-dialkylacetophenone; benzophenones such as benzophenone; Michler's ketone Michler's ketones such as benzyl; benzyls such as benzyl methyl ether; benzoins such as benzoin and 2-methylbenzoin; benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin butyl ether; Benzyl dimethyl ketals; thioxanthones such as thioxanthone; propiophenone, anthraquinone, acetoin Butyroin, Toruoin, benzoyl benzoate, alpha-acyloxime esters may be mentioned carbonyl compounds such as.

  Examples of the photopolymerization initiator include sulfur compounds such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetramethylthiuram monosulfide, thioxanthone, 2-chlorothioxanthone; azobisisobutyronitrile, azobis- Azo compounds such as 2,4-dimethylvaleronitrile; peroxides such as benzoyl peroxide and di-tert-butyl peroxide;

  These photopolymerization initiators are generally added to the polymerizable monomer composition in a proportion of 0.001 to 10% by weight, preferably 0.01 to 5% by weight. When a hydrogen abstraction type photopolymerization initiator such as benzophenone is used, a part of the α, β-unsaturated carboxylic acid can be grafted onto the rubber base material to further improve interlayer adhesion. General-purpose additives such as other sensitizers and light stabilizers may be added together with the photopolymerization initiator.

  When the coating film is heated and thermal polymerization is performed, it is preferable to use a thermal polymerization initiator that is thermally dissociated and exhibits a function as an initiator. Examples of the thermal polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate; 2,2′-azobis [2-methyl-N- [1,1-bis (hydroxymethyl) ethyl] propionamide], 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (methylisobutyrate), 2,2 '-Azobis (N, N'-dimethyleneisobutylamidine) dihydrochloride, 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide, 1,1'-azobis (cyclohexane-1 -Azo polymerization initiators such as carbonitrile; hydroperoxides such as tert-alkyl hydroperoxide; di-tert-butyl peroxide, di- Milperoxide, lauroyl peroxide, benzoyl peroxide, tert-butylperoxy-2-ethylhexanoate, tert-hexylperoxy-2-ethylhexanoate, tert-butylperoxypivalate, di-isopropylperoxide Peroxides such as oxydicarbonate, di-tert-butylperoxyisophthalate, 1,1 ′, 3,3′-tetramethylbutylperoxy-2-ethylhexanoate, tert-butylperoxybutyrate; When a thermal polymerization initiator is used, it is generally added in a proportion of 0.001 to 10% by weight, preferably 0.01 to 5% by weight, in the polymerizable monomer composition.

  In the polymerizable monomer composition used in the present invention, a thickener, if necessary, within a range not inhibiting the polymerization of α, β-unsaturated carboxylic acid and the ionic crosslinking reaction with polyvalent metal ions. Inorganic layered compounds, dispersants, surfactants, softeners, heat stabilizers, antioxidants, oxygen absorbers, colorants, antiblocking agents, polyfunctional monomers, and the like can be included.

  As for α, β-unsaturated carboxylic acid, a part of the degree of neutralization of 0 to 90% based on chemical equivalent based on polyvalent metal (for example, about 2 to 40% based on chemical equivalent) is monovalent as necessary. It can be replaced with a metal neutralized product. As the monovalent metal, sodium, potassium and lithium are used, and sodium and potassium are particularly preferable. For neutralization, these monovalent metals may be added to the composition as hydroxides, halides, carbonates, organic acid salts, and the like. By including a neutralized product of α, β-unsaturated carboxylic acid with these monovalent metals, the gas barrier properties of the resulting gas barrier layer can be further improved.

(Coating and polymerization)
In order to apply the polymerizable monomer composition onto at least one surface of the rubber base material, a spray method, a dipping method, a coating method using a coater, a printing method using a printing machine, etc. Any coating method can be used depending on the shape of the substrate coated surface. When applying using a coater or printing machine, for example, gravure coaters such as direct gravure method, reverse gravure method, kiss reverse gravure method, offset gravure method; reverse roll coater, micro gravure coater, air knife coater, dip coater, Various systems such as a bar coater, comma coater, and die coater can be employed.

  In this way, after the polymerizable monomer composition is applied on at least one surface of the rubber base material to form a coating film, the wet state is maintained without substantially drying the solvent of the coating film. The partially neutralized α, β-unsaturated carboxylic acid monomer is polymerized by irradiating the coated film with ionizing radiation and / or heat treatment, thereby containing a partially neutralized polycarboxylic acid polymer. A polymer layer (gas barrier layer) is formed.

  Prior to the application of the polymerizable monomer composition to the rubber base material, on the coated surface of the rubber base material, for the purpose of improving the adhesion of the polymer layer mainly obtained as needed to the rubber base material. Further, surface treatment such as etching, corona discharge, plasma treatment, electron beam irradiation or primer coating can be performed. Moreover, primer application may be effective also in the meaning which adjusts the excess roughness of the rubber base-material surface.

  Considering that the surface average roughness Ra of the rubber substrate is about 0.1 to 10 μm, the thickness of the in-situ polymer layer (and the total of the primer layer provided as necessary) is the conventional thickness. It is preferably thicker than the normal thickness of the gas barrier layer made of the polycarboxylic acid polyvalent metal cross-linked product, 0.1 to 50 μm, and more preferably 0.5 to 20 μm.

  The ionizing radiation applied to the wet coating film of the polymerizable monomer composition is preferably ultraviolet rays, electron beams (beta rays), gamma rays, and alpha rays, and more preferably ultraviolet rays and electron beams. In order to irradiate ionizing radiation, an apparatus that generates each radiation source is used. In order to irradiate an electron beam, an accelerated electron beam extracted from an electron beam accelerator of 20 to 2000 kV is usually used. The irradiation dose of the accelerated electron beam is usually 1 to 300 kGy, preferably 5 to 200 kGy. The penetration depth of the electron beam into the irradiated object varies depending on the acceleration voltage. The higher the acceleration voltage, the deeper the electron beam penetrates. When an electron beam is used, the adhesion between the rubber substrate and the in-situ polymer layer can be improved by the graft reaction of the α, β-unsaturated carboxylic acid to the rubber substrate.

  To irradiate ultraviolet rays, using UV irradiation devices such as germicidal lamps, fluorescent lamps for ultraviolet rays, carbon arc, xenon lamps, low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultra high pressure mercury lamps, metal halide lamps, electrodeless lamps, Irradiate light including a wavelength region of 200 to 400 nm. The lamp output of the UV irradiation device is displayed as an output wattage (W / cm) per 1 cm of emission length. As the wattage per unit length increases, the ultraviolet intensity generated increases. The lamp output is usually selected from the range of 30 to 300 W / cm. The light emission length is usually selected from the range of 40 to 2500 mm.

  In order to form the in-situ polymer layer by heating the wet coating film, the coating film is usually heated to a temperature of 50 to 250 ° C, preferably 60 to 220 ° C, more preferably 70 to 200 ° C. Examples of the heating means include a method of heating the coating film using a heater, and a method of passing the coating film through a heating furnace whose temperature is controlled. The heating time is usually 1 minute to 24 hours, preferably 1 minute to 12 hours, more preferably 5 to 120 minutes. It is preferable from the viewpoint of gas barrier property of the in-situ polymer layer that the heating time is lengthened as the heating temperature is low and the heating time is shortened as the heating temperature is high.

  When it is necessary to remove the polymerization inhibition effect due to oxygen when forming the in-situ polymer layer, the irradiation with ionizing radiation and / or heat treatment is performed in an inert gas atmosphere such as nitrogen gas, carbon dioxide gas, or rare gas. It is preferable to carry out below. In order to remove the polymerization inhibition effect due to oxygen, it is preferable to coat the surface of the wet coating film formed on the substrate with another substrate (coating material). Examples of other base materials used as the covering material include, but are not limited to, a light-transmissive resin cover film, a glass plate, paper, and aluminum foil.

  As the light-transmissive resin cover film, a polyolefin film, a polyester film, a polyamide film, or the like is preferably used. Here, the light transmittance means a property capable of transmitting ionizing radiation such as ultraviolet rays, and the light transmittance is not limited. In general, any plastic film that is transparent or translucent can be used as a light-transmissive resin cover film. In the case of using an electron beam as the ionizing radiation, an ionizing radiation transmissive base material that transmits an accelerating electron beam may be used. The type of the base material may be a transparent or translucent base material such as a light-transmitting resin cover film. It is not limited to materials. By the above process, the wet coating film is treated by irradiation with ionizing radiation and / or heating while holding the wet coating film between the rubber substrate and the other substrate (coating material). Thus, a rubber-like molded product having a layer configuration of “rubber substrate / polymer layer / substrate” can be obtained. Furthermore, a rubber-like molded product having a layer configuration of “rubber substrate / polymer layer” can be obtained by adding another step of peeling the substrate (coating material).

(Metal application processing)
When an in-situ polymer layer is formed using an α, β-unsaturated carboxylic acid that is not neutralized or has a low degree of neutralization, a polycarboxylic acid can be obtained by, for example, applying an aqueous solution in which metal ions are dissolved after polymerization. The neutralization degree of the acid can be increased and the gas barrier property can be improved. As the metal ion, at least one metal ion selected from divalent metal ions and trivalent metal ions can be used from the viewpoint of gas barrier properties. Furthermore, monovalent metal ions can be used in combination as required. With respect to these metal ion species or metal compound species that give these metal ions, those described above as those used for neutralization of the α, β-unsaturated carboxylic acid can be appropriately selected.

(Heat treatment)
When an in-situ polymer layer is formed by irradiation with ionizing radiation and / or heating, and when the above-described post-polymerization metal application is performed, the gas barrier property can be further improved by removing the residual solvent by heat treatment. can get. The heat treatment for this is performed by, for example, holding a molded body having an in-situ polymer layer formed on a rubber substrate at 50 to 220 ° C. for 1 minute to 24 hours.

(Rubber shaped product)
The rubber-like molded product of the present invention thus obtained has an oxygen permeability of 100 × 10 ⁻⁴ cm ³ (STP) / (m ² · s · MPa measured under, for example, drying conditions at a temperature of 30 ° C. and a relative humidity of 0%. ) Gas barrier properties represented by the following. When α, β-unsaturated carboxylic acid having a neutralization degree of 10 to 90% on the chemical equivalent basis is used, 90 × 10 ⁻⁴ cm ³ (STP) / (m ² · s under the same drying conditions. When the α, β-unsaturated carboxylic acid having a degree of neutralization of 45 to 75% based on the chemical equivalent is used, the temperature is 30 ° C. and the relative humidity is 80%. A water-resistant gas barrier property represented by an oxygen permeability of 50 × 10 ⁻⁴ cm ³ (STP) / (m ² · s · MPa) or less under high humidity conditions is obtained.

  The gas barrier rubber-like molded article of the present invention utilizes the above-described excellent gas barrier property and characteristic stretch deformation property or impact resistance, so that a tire or its tube that requires air pressure retention, oxygen permeation inflow and Gasoline tanks that require prevention of permeation of flammable volatile gases, products such as tableware containers and carbonated beverage containers that require particularly high impact resistance in addition to the requirement of prevention of oxygen permeation to prevent deterioration of the quality of contents Alternatively, it is used as a molding precursor (semi-finished product).

  Hereinafter, the present invention will be described more specifically with reference to production examples (Examples, Comparative Examples, Reference Examples). In addition, the physical properties described in the present specification are based on measurement values obtained by the following methods.

<Oxygen permeability>
The oxygen permeability of the rubber-like molded body (the oxygen permeability of the rubber base material is sufficiently large, and thus it is evaluated that it substantially matches the oxygen permeability of the polymer layer) is modern control (Modern Control). Using an oxygen permeability tester “Oxtran 2/20” manufactured by the company, measurement was performed under conditions of a temperature of 30 ° C. and a relative humidity of 0% (or 80%). The measuring method was performed in accordance with ASTM D3985-81 (corresponding to JIS K7126 method B). The unit of the measured value is cm ³ (STP) / (m ³ · s · MPa). “STP” means standard conditions (0 ° C., 1 atm) for defining the volume of oxygen.

<Surface roughness>
The surface smoothness of the substrate was evaluated using an ultra-deep shape measurement microscope (“VK-8500” manufactured by KEYENCE). The evaluation method measured surface average roughness Ra according to JIS B0601.

  In the following description, “part” and “%” regarding the blending ratio are based on weight. The degree of neutralization (%) is based on the chemical equivalent.

(Preparation of coating solution)
Of the chemicals (unsaturated carboxylic acid, polyvalent metal compound and initiator) used in the preparation of the coating liquid (polymerizable monomer composition), Zn diacrylate (polyvalent metal compound) is manufactured by Aldrich. Except for, other drugs are manufactured by Wako Pure Chemical Industries, Ltd.

[Example 1]
Acrylic acid is applied as it is to coating liquid No. It was set to 1.

[Example 2]
2.50 parts of acrylic acid, 0.50 parts of zinc oxide, 0.14 parts of sodium hydroxide and 0.20 parts of benzophenone were dissolved in 1.50 parts of distilled water to obtain a coating solution No. 2 was obtained.

[Example 3]
Dissolving 3.00 parts of acrylic acid and 1.00 parts of zinc oxide in 2.50 parts of distilled water, the coating solution No. 3 was obtained.

[Example 4]
Dissolve 3.00 parts of acrylic acid and 0.60 parts of calcium carbonate in 4.50 parts of distilled water. 4 was obtained.

[Example 5]
A coating liquid No. 1 was prepared by dissolving 0.50 parts of acrylic acid, 1.50 parts of zinc diacrylate, and 0.10 parts of ammonium persulfate in 1.80 parts of distilled water. 5 was obtained.

[Example 6]
Dissolve 3.00 parts of methacrylic acid and 0.55 parts of magnesium oxide in 2.30 parts of distilled water. 6 was obtained.

[Example 50]
Dissolve 1.50 parts of zinc diacrylate in 2.50 parts of distilled water to obtain coating solution No. 50 was obtained.

The general composition of the coating solution obtained above is summarized in Table 1 below.

(Production example of gas barrier rubber-like molded product)
Various coating liquids were applied onto various rubber base materials shown in Tables 2 to 3 below, UV irradiation or electron beam (EB) irradiation, and heat treatment as necessary, to obtain a gas barrier rubber-like molded body. . The contents of various base materials indicated by symbols are as follows.

<Rubber base material>
NBR # 500: Nitrile rubber sheet having a thickness of 500 μm (“Nitrile rubber IN-80” manufactured by Irumagawa Rubber Co., Ltd .; tensile modulus (JIS K7113) = 6 MPa, surface average roughness Ra (JIS B0601) = 2 μm)
CR # 1000: 1 mm thick chloroprene rubber sheet (“Irokawa Rubber Co., Ltd.“ Chloroprene Rubber NEO-180 ”)
EPDM # 500: Ethylene-propylene rubber sheet having a thickness of 500 μm ("Ethylene-propylene rubber EP-5065" manufactured by Irumagawa Rubber Co., Ltd.)
Si # 300: Silicone rubber sheet with a thickness of 300 μm (“Silicone rubber IS-825” manufactured by Irumagawa Rubber Co., Ltd.)
F # 500: Fluoro rubber sheet with a thickness of 500 μm (Irumakawa Rubber Co., Ltd. “Fluoro rubber JF-900”)
U # 1000: 1 mm thick urethane rubber sheet ("urethane rubber IUC-749" manufactured by Irumagawa Rubber Co., Ltd.)
BR # 1000: 1 mm thick butyl rubber sheet (“VB260N” manufactured by Kureha Elastomer Co., Ltd.)
SBR # 1000: 1 mm thick styrene-butadiene rubber sheet (“GB450A” manufactured by Kureha Elastomer Co., Ltd.)

<Coating substrate>
ONy # 15: Biaxially stretched 6 nylon film with a thickness of 15 μm treated with internal corona treatment (“EMBLEM ONBC” manufactured by Unitika Ltd.)
OPP # 20: Biaxially stretched polypropylene film with a thickness of 20 μm treated with single-sided corona treatment (“Lelephan BO” manufactured by Toray Industries, Inc.)
PET # 12: Polyethylene terephthalate film having a thickness of 12 μm (“E5100” manufactured by Toyobo Co., Ltd .; tensile modulus (JIS K7100) = 4000 MPa; surface average roughness Ra = 0.02 μm)

(Production example by UV irradiation-heat treatment)
[Example 1]
Coating liquid No. 1 prepared in Example 1 above. 1 was applied on NBR # 500 (nitrile rubber sheet having a thickness of 500 μm) using a desktop bar coater (“K303PROFER” manufactured by RK Print-Coat Instruments) so that the wet coating amount was 24 g / m ² . Immediately after coating using a UV irradiation device (“COMPACT UV CONVEYOR CSOT-40” manufactured by GS YUSASA) on the wet film, the lamp output is 120 W / cm, the conveyance speed is 5 m / min, and the lamp height. The coating film was polymerized by irradiating with ultraviolet rays (UV light) under the condition of 24 cm.

  The rubber sheet subjected to the above treatment was heat-treated in a gear oven at 120 ° C. for 5 minutes to obtain a rubber-like molded body, and then the oxygen permeability was measured. A summary of the layer structure, UV irradiation conditions, heat treatment conditions, and measured oxygen permeability are shown in Table 2 below together with the following examples and comparative examples.

[Examples 2-5 and Comparative Examples 1-2]
A rubber-like molded body was obtained in the same manner as in Example 1 except that the rubber base material, coating liquid, wet coating amount, coating base material, UV irradiation condition and heat treatment condition were changed as shown in Table 2. In Examples 2 and 5, the heat treatment after UV irradiation was omitted. Moreover, about Examples 3-5, after coat | covering the coating liquid layer with the coating base material 2 shown in Table 2, the lamp output was increased from 120 W / cm to 160 W / cm, and UV irradiation was performed. In Examples 1 to 5, a transparent polymer coating film was formed, but the polymer layer of Comparative Example 2 was whitened.

  As is apparent from Table 2 above, Example 1 in which a gas barrier layer was formed by an in-situ polymer layer of the coating liquid as compared with Comparative Example 1 in which UV irradiation was performed without using the coating liquid. The rubber-like molded body of ˜5 has a remarkable improvement in gas barrier properties (decrease in oxygen permeability). In addition, the rubber-like molded product of Comparative Example 2 in which a Zn-neutralized acrylic acid polymer layer having a neutralization degree of 100% was formed had a neutralized (meth) acrylic acid polymer layer having a neutralization degree of 0 to 90%. Compared to the rubber-like molded product of the present invention, it can be seen that the gas barrier property is an order of magnitude lower due to the whitening of the polymer layer.

(Example of production by EB irradiation-heat treatment)
[Example 6]
Coating liquid No. 1 prepared in Example 1 above. 1 was coated on NBR # 500 (nitrile rubber sheet having a thickness of 500 μm) by using the same table bar coater as in Example 1 so that the wet coating amount was 12 g / m ² . Immediately after coating, ONy # 15 (biaxially stretched 6 nylon film having a thickness of 15 μm) was placed on the wet paint film surface to obtain a laminate having a layer structure of rubber substrate / coating film / ONy. . Next, from the coated substrate (ONy) side, using an EB irradiation device of a tray transfer conveyor type (“CB250 / 15 / 180L” manufactured by Iwasaki Electric Co., Ltd.), an acceleration voltage of 150 kV, a transfer speed of 10 m / min, and an irradiation dose of 50 kGy The coating was polymerized by irradiating an electron beam (EB) under the conditions.

  The rubber sheet subjected to the above treatment was heat-treated in a gear oven at 180 ° C. for 60 minutes to obtain a rubber-like molded product, and then the oxygen permeability was measured. The summary of the layer structure, EB irradiation conditions, heat treatment conditions, and oxygen permeability are shown in Table 3 below together with the following examples and comparative examples.

[Examples 7 to 10 and Comparative Examples 1 and 2]
A rubber-like molded body was obtained in the same manner as in Example 1 except that the rubber base material, coating liquid, wet coating amount, coating base material, EB irradiation, and heat treatment conditions were changed as shown in Table 3. In Examples 7, 9, and 10, the heat treatment after EB irradiation was omitted, and in Examples 8 to 10, coating of the coating surface with the coating substrate was omitted. In Examples 6 to 10, a transparent polymer layer was formed, but the polymer layer of Comparative Example 4 was whitened.

(Example of manufacturing by heating)
[Example 11]
Coating liquid No. 1 prepared in Example 5 above. 5 was coated on SBR # 1000 (styrene-butadiene rubber sheet having a thickness of 1 mm) using the same desktop bar coater as in Example 1 so that the wet coating amount was 24 g / m ² . After coating, an Al foil having a thickness of 50 μm was quickly covered on the surface of the wet coating film to obtain a laminate having a layer structure of rubber substrate / coating film / Al. Next, this laminate was placed in a gear oven, heated at 180 ° C. for 120 minutes to polymerize the coating film, and then the Al foil was peeled off to obtain a rubber-like molded product according to the present invention. The oxygen permeability of 17 × 10 ⁻⁴ [cm ³ (STP) / (m ² · s · MPa)] was obtained in the same manner as in 1. The outline is added to Table 3 for convenience.

(Extension following property of gas-barrier rubber-like molded product)
The rubber-like molded bodies obtained in Examples 3 and 6 were each uniaxially at a tensile speed of 300 / min using a tensile compression tester (“Tensilon RCT-1210A” manufactured by A & D Co., Ltd.). The film was stretched 10% in the direction and held in this state for 1 minute, and then the tensile force was released. With respect to the rubber-like molded body after this tensile drawing, the appearance (peeling of the polymer layer) and the oxygen permeability were evaluated.

As a result, for the rubber-like molded products of Examples 3 and 6, no peeling of the polymer layer was observed, and 4 × 10 ⁻⁴ and 73 × 10 ⁻⁴ [cm ³ (STP) / (m ² × s · MPa)] and is substantially equivalent to 3 × 10 ⁻⁴ and 75 × 10 ⁻⁴ [cm ³ (STP) / (m ² · s · MPa)] before the tensile stretching test. It was confirmed to show oxygen permeability.

[Example 12]
[Rubber composition A]
According to the following composition, sulfur and zinc oxide were kneaded to prepare a masterbatch, and then a rubber composition A kneaded with the masterbatch, sulfur and zinc oxide was obtained with an 8-inch roll to obtain a pneumatic tire for passenger cars. 195 / 65R15 (that is, a radial (R) tire having a cross-sectional width of 195 mm and a flatness (height / width) of 65% and a rim diameter of 15 inc) was produced.

Rubber composition A (compounding unit: parts by weight)
Natural rubber (“RSS # 3” manufactured by Tech Be Hang) 40
BR-IIR (“Bromobutyl 2244” manufactured by JSR Corporation) 60
HAF (Mitsubishi Chemical Corporation “Diamond Black H”) 50
Oil (“SUNPAR2280” manufactured by Nippon San Oil Co., Ltd.) 10
Stearic acid (made by Wako Pure Chemical Industries) 2
Zinc oxide (Mitsui Mining & Smelting Co., Ltd. “Zinc Hana 1”) 3
Sulfur (made by Wako Pure Chemical Industries) 1

[Manufacture of gas-barrier rubber-like molded product (tire)]
Coating liquid No. obtained in Example 1 above. 1 is applied to the inside of the tire using a spray gun so that the wet coating amount is about 15 g / m ^2, and the irradiation amount is about 600 W · sec using a UV irradiation device (“handy cure”). A tire having a gas barrier layer formed thereon was obtained by irradiating the wet coating film with ultraviolet rays so as to be / cm ² .

[Evaluation]
The tire with the gas barrier layer formed above and the tire without the gas barrier layer formed (the coating liquid for forming the gas barrier layer and the UV irradiation are not applied) are respectively set to 100 km at an initial internal pressure of 200 kPa. It was 10000 km traveled by pressing with a load of 6 kN onto a drum having a rotational speed corresponding to a speed of / h. After running tests with these two types of tires, each was further left for 3 months, and then each internal pressure was measured. When the internal pressure retention coefficient was determined by the following equation, a value of 0.4 was obtained. This indicates that the internal pressure reduction rate of the tire with the gas barrier layer formed is reduced by 40% compared to the tire without the gas barrier layer, and the internal pressure retention of the tire is improved.

[Equation 1]
Internal pressure retention coefficient = (200−a) / (200−b)
a: Running test of tire with gas barrier layer formed and internal pressure after standing for 3 months b: Running test of tire without gas barrier layer formed and internal pressure after standing for 3 months

[Example 13]
A zinc acetate aqueous solution (concentration of 5% by weight) was applied to the coated polymer layer of the tire formed with the gas barrier layer produced in Example 12 with a spray gun, washed with water, and neutralized with the carboxylic acid polymer as the gas barrier layer. The tire which performed the process which raises a degree further was obtained. This tire had an internal pressure retention coefficient of 0.1, and it was confirmed that the internal pressure retention characteristics were improved by the treatment with the aqueous zinc acetate solution.

[Example 14]
Coating liquid No. obtained in Example 1 above. In place of coating liquid No. 1 obtained in Example 5 above. A tire having a gas barrier layer formed thereon was prepared in the same manner as in Example 12 except that No. 5 was used. This tire had an internal pressure retention coefficient of 0.1, and an internal pressure retention property improved over that of Example 12 was obtained.

  As described above, according to the present invention, there are provided a rubber-like molded product (product or semi-finished product) having excellent gas barrier properties in addition to stretchable deformation and impact resistance as essential characteristics, and a method for producing the same. The

Claims (17)

A rubber base material having a certain thickness, and a gas barrier layer laminated on at least one of two surfaces sandwiching the thickness of the rubber base material, the gas barrier layer being 0 to 0 on a chemical equivalent basis by a polyvalent metal α has a 90% neutralized carboxyl groups, beta-Ri Do from the spot polymer layer of an unsaturated carboxylic acid, and was stretched 10% in one axial direction, after holding for 1 minute in this state, a tensile force A gas-barrier rubber-like molded article characterized in that , in an open state, the gas barrier layer does not peel off and exhibits an oxygen permeability equivalent to that before tensile stretching . The α, β-unsaturated carboxylic acid is acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, senetic acid, tiglic acid, sorbic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, maleic anhydride The rubber-like molded object according to claim 1, which is at least one selected from the group consisting of acid, itaconic anhydride, and citraconic anhydride. The rubber-like molded product according to claim 1 or 2, wherein the polyvalent metal is a metal that gives a divalent ion or a trivalent ion. The rubber base material is natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, acrylonitrile-butadiene rubber, butyl rubber, ethylene-propylene rubber, chlorobrene rubber, acrylic rubber, chlorosulfonated polyethylene rubber, hydrin rubber, urethane rubber, many The rubber-like molded product according to any one of claims 1 to 3, comprising at least one selected from the group consisting of sulfurized rubber, silicone rubber and fluororubber. The rubber-like molded product according to any one of claims 1 to 4, wherein the rubber substrate has a shape of a sheet, a tire, a tube or cup, a hollow container such as a tank, or a precursor thereof. The oxygen permeability measured under a drying condition at a temperature of 30 ° C and a relative humidity of 0% is 100 x 10 ^-4 cm ³ (STP) / (m ² · s · MPa) or less. The rubber-like molded product described. An α, β-unsaturated carboxylic acid neutralized by 0 to 90% with a polyvalent metal on a chemical equivalent basis is formed on at least one of two surfaces sandwiching the thickness of a rubber base material having a certain thickness. 2. A gas barrier layer is formed by forming a coating film of a polymerizable monomer composition dissolved or dispersed in 0 to 85% by weight of a solvent based on the total amount and polymerizing in situ. The manufacturing method of the gas-barrier rubber-like molded object in any one of -6. The α, β-unsaturated carboxylic acid is acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, senecioic acid, tiglic acid, sorbic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, maleic anhydride The production method according to claim 7, which is at least one unsaturated carboxylic acid selected from the group consisting of an acid, itaconic anhydride, and citraconic anhydride. The production method according to claim 7 or 8, wherein the polyvalent metal is at least one polyvalent metal selected from the group consisting of divalent metals and trivalent metals. The method according to any one of claims 7 to 9, wherein the solvent of the polymerizable monomer composition is at least one solvent selected from the group consisting of water, alcohol, NMP, THF, and acetone. The manufacturing method according to claim 7, wherein the polymerizable monomer composition further contains at least one of a photopolymerization initiator and a thermal polymerization initiator. The rubber base material is natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, acrylonitrile-butadiene rubber, butyl rubber, ethylene-propylene rubber, chloroprene rubber, acrylic rubber, chlorosulfonated polyethylene rubber, hydrin rubber, urethane rubber. The production method according to claim 7, comprising at least one selected from the group consisting of polysulfide rubber, silicone rubber, and fluororubber. The production method according to any one of claims 7 to 12, wherein the in-situ polymerization treatment is treatment by irradiation with ionizing radiation or heating or both of the coating film in a wet state. The production method according to claim 13, wherein the polymerization treatment is performed after the wet coating film is coated with a film-like substrate. The production method according to claim 13 or 14, wherein the ionizing radiation is ultraviolet rays, electron beams, gamma rays, or alpha rays. The method according to any one of claims 7 to 15, further comprising a step of imparting at least one metal ion selected from the group consisting of divalent metal ions and trivalent metal ions to the gas barrier layer. The manufacturing method according to any one of claims 7 to 16, wherein the rubber substrate has a shape of a sheet, a tire, a tube or cup, a hollow container such as a tank, or a precursor shape thereof.