JP2008087435A - Gas barrier rubber molded body and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber molded body (a product or a half-finished product) having a gas barrier layer showing excellence in deformation followability and elongation and/or compression moldability laminated on a rubbery base material showing excellence in flexible deformability and impact resistance as its intrinsic property. <P>SOLUTION: The gas barrier rubbery molded body comprises the rubber base material having a certain thickness, and a gas barrier layer laminated on at least one surface of two surfaces pinching the thickness of the rubber base material, wherein the gas barrier layer is characteristically composed of a cross-linked body prepared by a reaction of a carboxyl group of a carboxyl group-containing polymer (A) with a reactive organic cross-linking agent (B). <P>COPYRIGHT: (C)2008,JPO&INPIT

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 Japanese Patent Application No. 2005-240665 Specification

  The main object of the present invention is to provide a gas barrier rubber-like molded article in which a gas barrier layer comprising an unsaturated carboxylic acid polymer layer crosslinked with an organic crosslinking agent is formed on a flexible and deformable rubber substrate. There is.

  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, The gas barrier layer is composed of a crosslinked product of an organic crosslinking agent (B) having reactivity with the carboxyl group of the polymer (A) having a carboxyl group.

  Some details on how the present invention has been achieved will be described.

  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 its gas barrier property. 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 unsaturated carboxylic acid polymer with an organic crosslinking agent as disclosed in Patent Document 6 is used instead of the crosslinked carboxylic acid polymer with a polyvalent metal. When a gas barrier layer made of a cross-linked product is formed, the gas barrier layer has the ability to follow the elastic deformation of the rubber base material and further maintain the gas barrier property even when subjected to molding with stretching or / and compression. Was found. Here, the surface roughness of the rubber base material is determined by the anchoring effect of the rubber base material so as to follow the deformation of the rubber base material of the gas barrier layer in the molding accompanied by expansion / contraction or stretching or / and compression of the rubber base material. This is thought to contribute to the improvement of 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, tray or cup, It can be in the shape of a hollow container such as a tank or a precursor thereof (for example, a half or a sheet-like semi-finished product for giving these shapes by sheet forming with bonding or stretching or / and compression). 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.

(Gas barrier layer)
The gas barrier rubber-like molded product of the present invention is reactive with the carboxyl group of the polymer (A) in which the gas barrier layer has a carboxyl group on at least one of the two surfaces sandwiching the thickness of the rubber base as described above. A gas barrier layer made of a crosslinked product of an organic crosslinking agent (B) having The rubber-like molded product of the present invention can also be formed by laminating and laminating a separately formed gas barrier layer via an appropriate adhesive, but in order to form a gas barrier layer with better adhesion, A gas barrier layer is formed by forming a coating film of a polymerizable monomer composition containing an unsaturated carboxylic acid (a) which is a precursor of a polymer (A) having a carboxyl group and an organic crosslinking agent (B), and performing in-situ polymerization. Is preferably formed.

(Polymerizable monomer composition)
The polymerizable monomer composition is obtained by dissolving the unsaturated carboxylic acid (a) and the organic crosslinking agent (B) in a solvent used in a proportion of 0 to 85% by weight based on the total amount of the composition, if necessary. Obtained by dispersing.

<Unsaturated carboxylic acid (a)>
As the unsaturated carboxylic acid (a) constituting the polymerizable monomer composition used in the present invention, the polycarboxylic acid metal crosslinked product used for forming a gas barrier layer in Patent Documents 1 to 5 is used. Specific examples of the carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, senecioic acid, tiglic acid, sorbic acid, maleic acid, Examples thereof include at least one selected from the group consisting of fumaric acid, itaconic acid, citraconic acid, mesaconic acid, maleic anhydride, itaconic anhydride, and 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.

<Organic crosslinking agent (B)>
In addition to the unsaturated carboxylic acid (a), the polymerizable monomer composition includes an organic crosslinking agent (B) having reactivity with the carboxyl group of the polymer (A) formed by in situ polymerization. . Examples of functional groups that give reactivity with carboxyl groups include methylol groups, epoxy groups, isocyanate groups, imide groups, and hydroxyl groups. As the organic crosslinking agent (B), an organic compound having one or more, preferably two or more of these functional groups is used, and specific examples thereof include methylol compounds such as N-methylolacrylamide (N-MAM); Epoxy compounds such as 4-epoxycyclohexenylmethyl-3 ', 4'-epoxycyclohexenecarboxylate; Isocyanate compounds such as hexamethylene diisocyanate; Imide compounds such as N, N-diisopropylcarbodiimide and N, N-dicyclohexylcarbodiimide; Polyvinyl alcohol (PVA), hydroxy compounds such as glycerin and starch.

  These organic crosslinking agents (B) have a weight ratio between the weight (Bw) and the weight (Aw) of the unsaturated carboxylic acid (a) or the polymer (A) having a carboxy group formed by in situ polymerization therefrom. (Aw / Bw) may be contained in the polymerizable monomer composition or in the gas barrier layer in an amount of 1 to 20, more preferably 1.1 to 15, particularly preferably 1.2 to 10. preferable. In any case where this ratio is less than 1 or more than 20, the gas barrier layer is poor in following the elastic deformation or deformation during molding of the rubber substrate through crosslinking of the gas barrier layer by addition of the organic crosslinking agent (B), The gas barrier properties of the resulting gas barrier layer also deteriorate.

  As described above, the organic crosslinking agent (B) is used to form a crosslinked gas barrier layer by reacting with the carboxyl group of the polymer (A). Previously, it is understood that as a kind of plasticizer, it also serves to supplement the followability of the gas barrier layer against deformation of the rubber substrate. Hydroxy compounds such as glycerin are preferable as the organic cross-linking agent (B) that functions to supplement the following properties of the gas barrier layer.

<Solvent>
In the polymerizable monomer composition used in the present invention, the unsaturated carboxylic acid (a) and the organic crosslinking agent (B) described above are dissolved or dispersed in 0 to 85% by weight of a solvent based on the total amount of the composition. Is obtained. The solvent is mainly used to adjust the coating suitability of the polymerizable monomer composition. For example, an unsaturated carboxylic acid that is liquid at room temperature such as acrylic acid or methacrylic acid can be applied without using a solvent. A polymerizable monomer composition (Example 1 etc. 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 lower limit of the amount of solvent to be used is determined by the applicability of the obtained polymerizable monomer composition, and the upper limit is determined in terms of the appearance of the resulting polymerizable monomer composition coating film and the solvent removal efficiency. Use of a solvent in excess of 85% by weight is not preferable because productivity and film formability may be deteriorated.

<Polymerization initiator>
In addition to the unsaturated carboxylic acid (a), the organic crosslinking agent (B) and the solvent, the polymerizable monomer composition used for forming the in-situ polymer layer contains a polymerization initiator. Also good. 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.

  In the case of irradiating the coating film with ultraviolet rays, it is not necessary to contain it, but it is preferable to contain a photopolymerization initiator in the polymerizable monomer composition from the viewpoint of film formability and polymerization efficiency. 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 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; benzyldimethyl ketal and the like 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 portion of the unsaturated carboxylic acid (a) 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.

  The polymerizable monomer composition further includes an unsaturated carboxylic acid (a) within a range that does not hinder the deformation followability of the gas barrier layer obtained by the crosslinking reaction between the polymer (A) and the organic crosslinking agent (B). ) May be included in an amount that neutralizes a part of the chemical equivalent of the carboxyl group, for example, up to 50%. As the metal ions, monovalent metal ions such as Na and K, which hardly inhibit the deformability of the generated gas barrier layer, are preferably used, but up to about 30% based on the chemical equivalent of the metal ions, zinc, calcium, Multivalent metal ions such as magnesium, copper, aluminum and iron or compounds thereof can also be included. These metal ions work in the direction of slightly inhibiting the deformability of the obtained gas barrier layer, but are preferable for improving the gas barrier property.

  In the polymerizable monomer composition used in the present invention, a thickener is optionally added within a range that does not inhibit the polymerization of the unsaturated carboxylic acid (a) and the crosslinking reaction between the organic crosslinking agent (B). , Inorganic layered compounds, dispersants, surfactants, softeners, heat stabilizers, antioxidants, oxygen absorbers, colorants, antiblocking agents, polyfunctional monomers, and the like.

(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, a gravure coater such as a 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.

  Thus, by applying the polymerizable monomer composition on at least one surface of the rubber substrate and forming a coating film, the coating film is irradiated with ionizing radiation and / or heat-treated, The unsaturated carboxylic acid monomer (a) is polymerized to form an in-situ polymer layer (gas barrier layer) containing a crosslinked product in which at least a part of the carboxyl group is reacted with an organic crosslinking agent.

  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 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 having an acceleration voltage 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 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 provide a step of coating the surface of the 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 performing the treatment by irradiation with ionizing radiation and / or heating on the coating film between the rubber substrate and the other substrate (coating material) provided by the step by the above-mentioned step, “rubber substrate / A rubber-like molded product having a layer structure of “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)
In this invention, in order to improve the gas barrier property of the formed in situ polymer layer, the process of providing a metal ion can be provided. Specifically, for example, by applying an aqueous solution in which metal ions are dissolved after polymerization, the degree of neutralization of the polycarboxylic acid can be increased and the gas barrier properties 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. About these metal ion seed | species or the metal compound seed | species which gives these metal ions, what was mentioned above as what is added to a polymerizable monomer composition as needed can be selected suitably.

(Heat treatment)
When the in-situ polymer layer is formed by irradiation with ionizing radiation and / or heating, and when the post-polymerization metal application treatment is performed, the residual solvent is removed by heat treatment, and the polymer (A) Gas barrier properties can be obtained by further promoting the crosslinking reaction between the organic crosslinking agent (B) and the organic crosslinking agent (B). 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)
According to the rubber-like molded product of the present invention thus obtained, the oxygen permeability measured under a high humidity condition of, for example, a temperature of 30 ° C. and a relative humidity of 80% is 100 × 10 ⁻⁴ cm ³ (STP) / (m ² · s · MPa) or less, preferably 85 × 10 ⁻⁴ cm ³ (STP) / (m ² · s · MPa) or less, more preferably 75 × 10 ⁻⁴ cm ³ (STP) / (m ² · s · MPa ) Water-resistant gas barrier properties represented by the following can be 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).

  In particular, the rubber-like molded product of the present invention has its gas barrier following the stretching or / and compression molding before the heat treatment for advancing the crosslinking reaction between the polymer (A) and the organic crosslinking agent (B). In order to maintain the properties, it is suitably used as a molding precursor (semi-finished product) for giving the product through such molding.

  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, so it is evaluated that it substantially matches the oxygen permeability of the gas barrier layer formed thereon). Using an oxygen permeability tester “Oxtran 2/20” manufactured by (Modern Control), measurement was performed under conditions of a temperature of 30 ° C. and a relative humidity of 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 ² · 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.

(Preparation of coating solution)
In each case, the unsaturated carboxylic acid (a), the organic crosslinking agent (B), the polymerization initiator, the metal ion source, and the solvent are mixed at the blending ratio shown in Table 1 below to obtain the polymerizable monomer composition used in the present invention. Corresponding coating solution No. 1 to 8 and a coating solution No. for comparison or reference. 50-52 were prepared. The main ingredient types and sources are as follows.

<Unsaturated carboxylic acid (a)>
Acrylic acid, methacrylic acid, maleic acid and itaconic acid are all manufactured by Wako Pure Chemical Industries, Ltd.

<Organic crosslinking agent (B)>
Hexamethylene diisocyanate is manufactured by Aldrich; N-MAM (N-methylolacrylamide) is manufactured by Soken Chemical Co., Ltd .; PVA (polyvinyl alcohol) and glycerin are manufactured by Wako Pure Chemicals; “Celoxide 2021” (trade name) (3,4-epoxycyclohexenylmethyl-3 ', 4'-epoxycyclohexene carboxylate) is manufactured by Daicel Chemical Industries.

<Polymerization initiator>
BP (benzophenone) is manufactured by Wako Pure Chemical Industries, Ltd.

(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)
NR # 1000: Natural rubber sheet with a thickness of 1 mm ("Natural rubber sheet G-3000" manufactured by Irumagawa Rubber Co., Ltd.)
SBR # 1000: 1 mm thick styrene-butadiene rubber sheet (“GB450A” manufactured by Kureha Elastomer Co., Ltd.)
BR # 1000: 1 mm thick butyl rubber sheet (“VB260N” manufactured by Kureha Elastomer Co., Ltd.)

<Coating substrate>
CNy # 20: unstretched nylon film having a thickness of 20 μm (“Rayfan NO 1041” manufactured by Toray Synthetic Films Co., Ltd.)
OPP # 20: Biaxially stretched polypropylene film with a thickness of 20 μm treated with single-sided corona treatment (“Trephan 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 having the composition shown in Table 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, a UV irradiation device (“COMPACT UV CONVEYOR CSOT-40” manufactured by GS YUASA Co., Ltd.) is used from the top of the coating film for a lamp output of 120 W / cm, a conveyance speed of 5 m / min, and a lamp height of 24 cm. The film was polymerized by irradiating with ultraviolet rays (UV light).

  The rubber sheet subjected to the above treatment was heat-treated at 150 ° C. for 5 minutes in a gear oven to obtain a rubber-like molded body, and then the oxygen permeability was measured. The 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, comparative examples and reference examples.

[Examples 2 to 5, Comparative Examples 1 to 3 and Reference Example 1]
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 3 to 5 and Comparative Example 2, the coating liquid layer was coated with the coating substrate shown in Table 2, and then the lamp output was increased from 120 W / cm to 160 W / cm, and UV irradiation was performed. .

In Example 3 and Comparative Examples 1 and 2, after UV irradiation and before heat treatment, using a biaxial stretching machine (“X6H-S” manufactured by Toyo Seiki Co., Ltd.) for 1 minute at a temperature of 160 ° C., Biaxial stretching was performed at a speed of 10 m / min and a magnification of 1.5 × 1.5 (= area magnification of 2.25). Furthermore, in Example 4, after the UV irradiation, the coated sheet was compression-molded with a mold having a radius of 10 cm and a depth of 0.25 cm (the area magnification accompanying this was 1.1 times). Then, a heat treatment was performed to obtain a rubber-like molded product having a circular tray shape.

As can be seen from the results in Table 2 above, according to Examples 1 to 5 according to the present invention, all were 100 × 10 ⁻⁴ [cm ³ (STP) under high humidity conditions of 30 ° C. and 80% RH. / M ² · s · MPa] A water-resistant gas barrier property typified by an oxygen permeability of less than or equal to is obtained, and the gas barrier property is also obtained after stretch molding (Example 3) and after compression molding (Example 4). Maintained.

On the other hand, in Comparative Example 1 without coating with the gas barrier layer, the rubber-like molded body obtained by Comparative Example 3 formed after stretching and without using the unsaturated carboxylic acid (a) was 10 [cm]. ³ (STP) / m ² · s · MPa], indicating a poor gas barrier property. On the other hand, the rubber-like molded product of Comparative Example 2 coated with a gas barrier property that was not crosslinked with the organic crosslinking agent (B) was 80 × 10 ⁻³ (= 800 × 10 ⁻⁴ ) [cm ³ (STP) / m ² · s · MPa], and the rubber-like molded product of Reference Example 1 in which the amount of the organic crosslinking agent (B) is excessive is 40 × 10 ⁻³ (= 400 × 10 ⁻⁴ ) [cm ³ (STP) / m ² · s · MPa] and the desired gas barrier properties are not obtained.

(Example of production by EB irradiation-heat treatment)
[Example 6]
Coating liquid No. 1 having the composition shown in Table 1 above. 1 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 12 g / m ² . After coating, CNy # 20 (non-stretched nylon film having a thickness of 20 μm) was immediately covered on the surface of the coating film to obtain a laminate having a layer structure of rubber substrate / coating film / CNy. Next, from the coated substrate (CNy) side, using an EB irradiation apparatus 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, comparative examples and reference examples.

[Examples 7 to 10, Comparative Examples 4 to 6 and Reference Example 2]
A rubber-like molded body was obtained in the same manner as in Example 6 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 Example 7, the coating liquid No. was applied to a styrene-butadiene rubber tube having a diameter of 100 mm and a thickness of 1 mm. 3 was applied by dipping, wrapped with a 12 μm thick PET film, and then coated on both sides under the conditions of an acceleration voltage of 300 kV, a conveyance speed of 10 m / min, and an irradiation dose of 50 kGy using the same EB irradiation apparatus as in Example 6. After EB irradiation, heat treatment was performed under the same conditions as in Example 6. The obtained coated rubber tube was cut open and formed into a sheet shape, and the oxygen permeability was measured.

  In Examples 8 to 9 and Comparative Example 5, after EB irradiation and before heat treatment, using a biaxial stretching machine (“X6H-S” manufactured by Toyo Seiki Co., Ltd.) for 1 minute at 160 ° C., Biaxial stretching was performed at a speed of 10 m / min and a magnification of 1.5 × 1.5 (= area magnification of 2.25). Further, in Example 10, after EB irradiation, the obtained rubber sheet was compression-molded with a mold having a radius of 10 cm and a depth of 1 cm (the area magnification accompanying this was 1.4 times). A heat treatment was carried out therein to obtain a rubber-like molded product having a circular tray shape.

As can be seen from the results in Table 3 above, according to Examples 6 to 10 according to the present invention, all were 100 × 10 ⁻⁴ [cm ³ (STP) under high humidity conditions of 30 ° C. and 80% RH. / M ² · s · MPa] A water-resistant gas barrier property represented by an oxygen permeability of less than or equal to is obtained, and the gas barrier property is after stretch molding (Examples 8 to 9) and after compression molding (Example 10). ) Is also maintained.

On the other hand, Comparative Example 4 without coating with the gas barrier layer and Comparative Example 5 coated with the gas barrier layer that was not crosslinked with the organic crosslinking agent (B) were both 10 [cm ³ (STP) / m. ² · s · MPa], which shows an inferior gas barrier property, and the compounding amount of the rubber-like molded article of Comparative Example 6 formed without using the unsaturated carboxylic acid (a) and the organic crosslinking agent (B) is excessive. The rubber-like molded bodies obtained in Example 2 were 80 × 10 ⁻³ (= 800 × 10 ⁻⁴ ) [cm ³ (STP) / m ² · s · MPa] and 40 × 10 ⁻³ (= 400 ×, respectively). 10 ⁻⁴ ) [cm ³ (STP) / m ² · s · MPa] and the desired gas barrier properties are not obtained.

(Evaluation by tire structure)
[Example 11]
[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 ratio (height / width) of 65% and a rim diameter of 15 inches) 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 (manufactured by Wako Pure Chemical Industries, Ltd.) 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)]
Formulation coating liquid No. 1 shown in Table 1 above. 2 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”). The tire was irradiated with ultraviolet rays so as to be / cm ² to form a gas barrier layer.

[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 12]
Coating liquid No. shown in Table 1 above. 4 on a rubber sheet having a thickness of 500 μm formed by the rubber composition A used in Example 11 above, using an EB irradiation coating line (manufactured by I. Electron Beam Co., Ltd.), a gravure wet coating amount was 24 g / m. ² and coated with CNy # 20 (unstretched nylon film having a thickness of 20 μm), followed by EB irradiation under the conditions of an acceleration voltage of 120 kV and an irradiation dose of 50 kGy, and rubber sheet A / polymer film / coating material An inner liner having a (CNy) layer structure was obtained. Using this inner liner, an automotive pneumatic tire 195 / 65R15 was formed by a conventional method, and the internal pressure retention coefficient was measured in the same manner as in Example 11. A coefficient of 1 was obtained.

  As described above, according to the present invention, a rubber-like molded article in which a gas barrier layer excellent in deformation followability and stretch or / and compression moldability is formed on a rubber base material excellent in stretch deformability and impact resistance ( Product or semi-finished product).

Claims (21)

Of a polymer (A) comprising 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, wherein the gas barrier layer has a carboxyl group A gas barrier rubber-like molded product comprising a crosslinked product of an organic crosslinking agent (B) having reactivity with a carboxyl group. The rubber-like material according to claim 1, wherein the gas barrier layer comprises an in-situ polymer on a rubber substrate of a polymerizable monomer composition containing an organic crosslinking agent (B) and an unsaturated carboxylic acid (a). Molded body. The polymer (A) containing the carboxyl group 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, The rubber-like molded object according to claim 1 or 2, which is a polymer of at least one unsaturated carboxylic acid (a) selected from the group consisting of maleic anhydride, itaconic anhydride and citraconic anhydride. The rubber-like molded object according to any one of claims 1 to 3, wherein the organic crosslinking agent (B) has two or more functional groups having reactivity with a carboxyl group. The rubber-like molded object according to any one of claims 1 to 4, wherein the functional group having reactivity with the carboxyl group of the organic crosslinking agent (B) is a methylol group, an epoxy group, an isocyanate group, an imide group, or a hydroxyl group. The rubber according to any one of claims 1 to 5, wherein the weight ratio (Aw / Bw) of the weight (Aw) of the polymer (A) to the weight (Bw) of the organic crosslinking agent (B) is 1 to 20. Shaped compact. The rubber-like molded object in any one of Claims 1-6 in which a part of carboxyl group of the polymer (A) containing the said carboxyl group is neutralized with the metal 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 7, 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 8, wherein the rubber substrate has a shape of a sheet, a tire, a tube, a tray or cup, a hollow container such as a tank, or a precursor thereof. The oxygen permeability measured under a high humidity condition at a temperature of 30 ° C and a relative humidity of 80% is 100 x 10 ^-4 cm ³ (STP) / (m ² · s · MPa) or less. The rubber-like molded object as described in 2. A coating film of a polymerizable monomer composition containing an unsaturated carboxylic acid (a) and an organic crosslinking agent (B) is formed on at least one of two surfaces sandwiching the thickness of a rubber base material having a certain thickness. The method for producing a gas barrier rubber-like molded article according to any one of claims 1 to 10, wherein the gas barrier layer is formed by forming and polymerizing in situ. The unsaturated carboxylic acid (a) 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 11, wherein the unsaturated carboxylic acid is at least one selected from the group consisting of citraconic anhydride, itaconic anhydride, and citraconic anhydride. The production method according to claim 11 or 12, wherein the polymerizable monomer composition further contains at least one of a photopolymerization initiator and a thermal polymerization initiator. The manufacturing method according to claim 11, wherein the polymerizable monomer composition further contains a metal ion. The manufacturing method according to any one of claims 11 to 14, wherein the molded body is subjected to a molding step including stretching or / and compression after in situ polymerization. The manufacturing method according to claim 11, further comprising a step of promoting crosslinking of the gas barrier layer by heat treatment. The manufacturing method according to claim 16, wherein after the in-situ polymerization, the formed body is subjected to a forming step including stretching or / and compression, followed by heat treatment. The production method according to any one of claims 11 to 17, wherein the in-situ polymerization is a polymerization treatment by irradiation with ionizing radiation, heating or both of the coating film. The manufacturing method of Claim 18 which superposes | polymerizes after coat | covering a coating film with a film-form base material. The manufacturing method according to claim 18 or 19, wherein the ionizing radiation is ultraviolet rays, electron beams, gamma rays, or alpha rays. The manufacturing method according to any one of claims 11 to 20, further comprising a step of providing at least one metal ion selected from the group consisting of divalent metal ions and trivalent metal ions to the gas barrier layer.