JP4677823B2 - Thermoplastic elastomer laminate - Google Patents

Description

  The present invention relates to a thermoplastic elastomer laminate, and more particularly to a thermoplastic elastomer laminate excellent in gas permeation resistance and excellent in durability at low temperatures.

  A technique of using a thermoplastic elastomer for an air permeation preventive layer of a pneumatic tire is known (see, for example, Patent Document 1). Such a thermoplastic elastomer has excellent gas permeation resistance, but the flexibility of the elastomer at a low temperature. There is a contradictory relationship between gas permeability and gas permeability, and there is a problem in durability in products with dynamic strain such as pneumatic tires and hoses.

Japanese Patent No. 2999188

  Accordingly, an object of the present invention is to provide a thermoplastic elastomer laminate having excellent gas permeation resistance and excellent durability.

  According to the present invention, the thermoplastic elastomers A and B and the vulcanized rubber C are laminated in the order of A layer / B layer / C layer as the thermoplastic elastomers A and B and the vulcanized rubber C. A laminate having a dynamic modulus of elasticity (MA, MB and MC) at −20 ° C. of MA / MB <0.8 and MC <MB is provided.

  According to the present invention, by covering the surface of the thermoplastic elastomer composition layer with high gas permeability resistance but insufficient fatigue resistance with a flexible thermoplastic elastomer, the gas permeability resistance is not greatly impaired. It is possible to obtain a thermoplastic elastomer laminate that can secure the properties.

  Examples of the resin component of the thermoplastic elastomers A and B of the laminate according to the present invention include polyamide resins (for example, nylon 6 (N6), nylon 66 (N66), nylon 11 (N11), nylon 12 (N12), Nylon 610 (N610), nylon 612 (N612), etc.), polyester resins (eg, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), etc.), polynitrile resins (eg, polyacrylonitrile (PAN)) ), Polymethacrylonitrile, etc.), polymethacrylate resins (eg, polymethyl methacrylate (PMMA), polymethacrylate ethyl, etc.), polyvinyl resins (eg, vinyl acetate, polyvinyl alcohol (PVA), poly Vinylidene fluoride (PDVC), polyvinyl chloride (PVC), etc.), cellulose resins (eg, cellulose acetate, cellulose acetate butyrate), fluororesins (eg, polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), etc.), imides Based resin (for example, aromatic polyimide (PI)).

  The thermoplastic elastomer used in the laminate according to the present invention is obtained by blending the thermoplastic resin and the elastomer. Examples of such an elastomer include a diene rubber and a hydrogenated product thereof (for example, NR, IR, etc.). , SBR, BR, NBR, etc.), olefin rubber (eg, ethylene propylene rubber (EPDM, EPM), IIR, etc.), acrylic rubber (ACM), halogen-containing rubber (eg, Br-IIR, C1-IIR, isobutylene para) Methyl bromide copolymer (BIMS), silicone rubber (eg, methyl vinyl silicone rubber, dimethyl silicone rubber, etc.), sulfur-containing rubber (eg, polysulfide rubber), fluoro rubber (eg, vinylidene fluoride rubber) Fluorine-containing vinyl ether rubber), thermoplastic Elastomers (e.g., styrene elastomers, olefin elastomers, ester elastomers, urethane elastomers, polyamide-based elastomer) and the like can be illustrated, it may be a blend of two or more thereof.

  The elastomer component may be dynamically vulcanized when mixed with a thermoplastic resin. Dynamic vulcanization refers to vulcanizing an elastomer component while melt-kneading a thermoplastic resin, an elastomer component, and a crosslinking agent. The vulcanizing agent, vulcanization aid, vulcanization conditions (temperature, time) and the like in the case of dynamic vulcanization may be appropriately determined according to the composition of the elastomer component to be added, and are not particularly limited. A general rubber vulcanizing agent (crosslinking agent) can be used as the vulcanizing agent. Specifically, as the sulfur vulcanizing agent, powder sulfur, precipitated sulfur, etc., for example, about 0.5 to 4 phr [parts by weight per 100 parts by weight of rubber component (polymer)] can be used.

  Specific examples of the organic peroxide vulcanizing agent that can be used in the present invention include dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, benzoyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3,2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2, 5-mono (t-butylperoxy) hexane, 1,3-bis (t-butylperoxyisopropyl) benzene, 4,4-di-t-butylperoxy-valeric acid-n-butyl ester and the like. . Examples of the thiourea vulcanization accelerator include ethylene thiourea and diethyl thiourea.

For the elastomer component, a general rubber compounding agent can be used in combination. For example, zinc white, stearic acid, oleic acid, and metal salts thereof can be used. The method for producing the thermoplastic elastomer composition is not particularly limited, but a thermoplastic resin component and an elastomer component (unvulcanized in the case of rubber) are melt-kneaded with a twin-screw kneading extruder or the like in advance, and a continuous phase ( It can be produced by dispersing an elastomer component as a dispersed phase (domain) in a thermoplastic resin forming a matrix phase. When the elastomer component is vulcanized, the elastomer component may be dynamically vulcanized by adding a vulcanizing agent under kneading. Further, various compounding agents (excluding the vulcanizing agent) to the thermoplastic resin or the elastomer component may be added during the kneading, but are preferably mixed in advance before kneading. The kneading machine used for kneading the thermoplastic resin and the elastomer component is not particularly limited, and a screw extruder, a kneader, a Banbury mixer, a biaxial kneading extruder, or the like can be used. As conditions for melt kneading, the temperature may be higher than the temperature at which the thermoplastic resin melts. The shear rate during kneading is preferably 1000 to 7500 sec ⁻¹ . The entire kneading time is from 30 seconds to 10 minutes, and when a vulcanizing agent is added, the vulcanization time after addition is preferably from 15 seconds to 5 minutes. The thermoplastic elastomer composition produced by the above method is then formed into a sheet-like film by extrusion molding or calendar molding. The method for forming a film may be a method of forming a film from a normal thermoplastic resin or thermoplastic elastomer.

  The film thus obtained has a structure in which the elastomer component (Y) is dispersed as a dispersed phase (domain) in the matrix of the thermoplastic resin (X). By adopting a dispersion structure in such a state, thermoplastic processing is possible, and sufficient rigidity can be imparted to the film as the air permeation prevention layer and sufficient rigidity by the effect of the resin layer as the continuous phase. In addition, it is possible to obtain molding processability equivalent to that of a thermoplastic resin at the time of molding regardless of the amount of the elastomer component, so that it can be formed into a film by an ordinary resin molding machine, that is, extrusion molding or calendar molding. Is possible.

  The composition ratio between the specific thermoplastic resin (X) and the elastomer component (Y) when blending the thermoplastic resin and the elastomer is not particularly limited, and the balance of film thickness, air permeation resistance, and flexibility is not limited. The weight ratio (X) / (Y) is preferably 10/90 to 90/10, more preferably 15/85 to 90/10.

  The vulcanized rubber C of the laminate according to the present invention is not particularly limited, but any diene rubber that has been conventionally used in the rubber industry for tires and others, such as natural rubber (NR). , Polyisoprene rubber (IR), various styrene-butadiene copolymer rubber (SBR), various polybutadiene rubber (BR), acrylonitrile-butadiene copolymer rubber (NBR), and ethylene-propylene-diene copolymer (EPDM) ), (Halogenated) butyl rubber and the like, and these can be used alone or as any blend. These vulcanized rubbers are made by adding various conventional compounding agents such as carbon black and silica, reinforcing agents, softeners, anti-aging agents, vulcanizing agents, vulcanization accelerators, etc. to the rubber component. It can be set as the layer of the vulcanized rubber C of the invention.

  The lamination method of the thermoplastic elastomer B layer and the vulcanized rubber C layer is not particularly limited and can be carried out by a conventionally known general method. Specifically, for example, between the B layer and the C layer, a method of bonding by adding an elastomer having a substituent that reacts with the B layer component to the C layer, or an adhesive capable of bonding to the B layer and the C layer is interposed. Can be used. For the A layer and the B layer, for example, a method using an adhesive or heat fusion can be used.

  The dynamic elastic modulus (MA, MB and MC) at −20 ° C. of the thermoplastic elastomers A and B and the vulcanized rubber C constituting the laminate according to the present invention is MA / MB <0.8 and MC <MB Preferably, the relationship MC / MC <0.5 is required. If the dynamic elastic modulus does not satisfy the above conditions, it is not preferable because the fatigue resistance is not excellent for the air permeability.

  The thermoplastic elastomer composition and rubber composition used in the present invention include, in addition to the above-described essential components, other reinforcing agents (fillers) such as carbon black and silica, vulcanization or crosslinking agents, vulcanization or crosslinking acceleration. Additives, various oils, anti-aging agents, plasticizers for tires, and other additives that are generally blended for general rubbers can be blended. The composition can be used to vulcanize or crosslink. The blending amounts of these additives may be conventional conventional blending amounts as long as the object of the present invention is not adversely affected.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, it cannot be overemphasized that the scope of the present invention is not limited to these Examples.

Standard Examples 1-4, Examples 1-2, and Comparative Example 1
The thermoplastic resin pellets A, B, D and E were prepared by mixing, extruding, cooling with water, and cutting the raw materials having the formulations shown in Tables I and II using a twin-screw mixer. The thermoplastic resin pellets were extruded using a blow molding machine to extrude a single-layer or two-layer cylindrical thermoplastic film, which was cut into strips to prepare a thermoplastic film. On the other hand, in the unvulcanized rubber compositions C and F, the components other than the vulcanization accelerator and sulfur are mixed using a closed mixer, and then the vulcanization accelerator and sulfur are added thereto, and the mixture is about 2 rolls. A 2 mm thick sheet was cut into a strip shape to prepare an unvulcanized rubber sheet.

  Next, the unvulcanized rubber sheet and the thermoplastic film obtained above are superposed in combinations as shown in Table III and Table IV, and heated and pressed at 180 ° C. for 10 minutes with a hot press, and both are vulcanized and bonded. Then, it was punched with a JIS No. 3 dumbbell to obtain a sample for fatigue test.

Physical property evaluation test method Fatigue test: Using a sample punched with a JIS No. 3 dumbbell, 40% constant strain elongation was repeatedly given in an atmosphere of −40 ° C. The fatigue life was assumed.

Air permeability: air permeability coefficient measurement method of film: Measured according to JIS K7126 “Plastic film and sheet gas permeability test method (Method A)”.
Test piece: The monolayer film produced in each example was used as a test piece, and air (N ₂ : O ₂ = 8: 2) was used as a test gas, and measurement was performed at a temperature of 30 ° C.

E ′ (−20 ° C.): The dynamic elastic modulus (E ′) of the single layer film is −20 ° C., 20 Hz, dynamic strain 10 ± 2% using a DVE-V4 type dynamic viscoelasticity measuring machine manufactured by Rheology. Measured in extension mode.
The results are shown in Tables I to IV, respectively.

  As shown in Table III, according to the cutting life in a 40% elongation fatigue test at −20 ° C., the A layer having a low elastic modulus is outside the standard example 1 and 2 in which single layer A or B and rubber are laminated. In Example 1 arranged in the above, fatigue resistance is good for air permeability. On the other hand, Comparative Example 1 in which the A layer is disposed on the inner side is greatly inferior in fatigue resistance in spite of almost the same air permeability as Example 1.

  As shown in Table IV, in contrast to the standard examples 3 and 4 using the single layers D and E, the second example of the present invention has an air permeability that is almost in the middle of the standard examples 3 and 4. Nevertheless, the fatigue resistance is close to that of standard example 3, and the balance between both characteristics is good.

  As described above, according to the present invention, a laminate having excellent gas permeation resistance and durability can be obtained, so that it can be used for flexible pressure vessels such as inner liner layers of pneumatic tires and inner layers of high pressure hoses. It is suitable for.

Claims (5)

In a laminate in which the thermoplastic elastomers A and B and the vulcanized rubber C are laminated in the order of A layer / B layer / C layer as layers, the dynamics of the thermoplastic elastomers A and B and the vulcanized rubber C at −20 ° C. Thermal elastic modulus (MA, MB and MC) is MA / MB <0.8 and MC <MB, and the thermoplastic elastomer A and / or B is a heat generated by dispersing rubber in a polyamide resin. A laminate that is a plastic elastomer .   The laminate according to claim 1, wherein the A layer and the B layer are bonded by heat fusion or an adhesive layer.   The laminate according to claim 1 or 2, wherein the B layer and the C layer are bonded with an adhesive having an elastic modulus lower than that of the B layer. The laminated body according to any one of claims 1 to 3 , wherein the vulcanized rubber C is a diene rubber composition. The laminated body according to any one of claims 1 to 4 , wherein the air permeability of the B layer is 50 x 10 ^-12 cm ³ · cm / cm ² · sec · cmHg or less.