JP2019035033A - Thermoplastic elastomer composition, air permeation-resistant film for tire, and pneumatic tire prepared therewith - Google Patents

Abstract

To provide a thermoplastic elastomer composition that makes it possible to obtain a resin film having excellent workability, flexibility, and rubber adhesion while maintaining at least air permeation resistance, an air permeation-resistant film for a tire prepared therewith, and a pneumatic tire prepared therewith.SOLUTION: A thermoplastic elastomer composition has a continuous phase composed of thermoplastic resin, and a dispersion phase composed of vulcanized rubber dispersed in the continuous phase. The vulcanized rubber contains chlorosulfonated polyethylene of 1-10 pts.mass relative to 100 pts.mass of butyl rubber.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermoplastic elastomer composition, an air permeation-resistant film for tires, and a pneumatic tire using the same.

  An inner liner is provided on the inner side surface of the pneumatic tire as an air permeation suppression layer in order to keep the tire air pressure constant. The inner liner is generally composed of a rubber layer such as butyl rubber or halogenated butyl rubber that is difficult for gas to permeate. However, the use of a resin film that can be thinned is being studied in order to reduce the weight of the tire.

  The air permeation-resistant resin film is obtained by melt-kneading a rubber component and a thermoplastic resin and dynamically crosslinking the thermoplastic resin as a continuous phase (matrix phase) and the rubber component as a dispersed phase (domain phase). A thermoplastic elastomer composition (Thermoplastic Vulcanizates; TPV) having a sea-island structure is used.

  Conventionally, a thermoplastic elastomer composition used for an air permeable resistant film is required to have excellent processability, flexibility, and adhesion to rubber. As a method for improving the flexibility, it is conceivable to increase the blending ratio of the rubber component. However, when the blending ratio of the rubber component is increased, the workability deteriorates, so that it is necessary to add a plasticizer. However, when a plasticizer is added, there is a problem that the air permeation resistance deteriorates.

  As a method of blending a large amount of a rubber component in a continuous phase with a small amount of plasticizer, for example, Patent Document 1 discloses dynamic crosslinking of a polyamide resin (A) and a halogenated isoolefin paraalkylstyrene copolymer rubber (B). In the method for producing a thermoplastic elastomer composition, the polyamide resin is modified by melt-kneading the polyamide resin (A) with a compound (C) that can be bonded to the terminal amino group of the polyamide resin in advance. It is disclosed that the reaction with the halogenated isoolefin paraalkylstyrene copolymer rubber (B) is suppressed, and a large amount of the halogenated isoolefin paraalkylstyrene copolymer rubber is blended while reducing the amount of the plasticizer for polyamide resin ( Claim 1, paragraph 0013, etc.).

  However, the invention described in the prior art document 1 is intended to improve the low temperature durability of the polyamide resin, and there is no description about processability, flexibility, and adhesion to rubber, and these characteristics There was room for further improvement.

Japanese Patent No. 5668876

  In view of the above points, the present invention provides a thermoplastic elastomer composition that provides a resin film excellent in processability, flexibility, and adhesion to rubber while maintaining at least air permeation resistance, and uses the same. An object of the present invention is to provide an air permeation resistant film for tires and a pneumatic tire using the same.

  The thermoplastic elastomer composition of the present invention has a continuous phase composed of a thermoplastic resin and a dispersed phase composed of vulcanized rubber dispersed in the continuous phase, and the vulcanized rubber is based on 100 parts by mass of butyl rubber. And 1 to 10 parts by mass of chlorosulfonated polyethylene.

  The air permeation-resistant film for tires of the present invention can be composed of the above thermoplastic elastomer composition.

  The pneumatic tire according to the present invention may be one using the above-mentioned tire air permeable resistant film.

  According to the thermoplastic elastomer composition of the present invention, an air permeable film excellent in processability, flexibility, and adhesion to rubber can be obtained while maintaining air permeability, and is suitable for tires. Can be used.

It is sectional drawing of the pneumatic tire which concerns on one Embodiment of this invention.

  Hereinafter, matters related to the implementation of the present invention will be described in detail.

  The thermoplastic elastomer composition according to the present embodiment has a sea-island structure in which a thermoplastic resin is a continuous phase (matrix phase) and a rubber component is a dispersed phase (domain phase).

  Examples of the thermoplastic resin constituting the continuous phase include nylon 6, nylon 66, nylon 46, nylon 11, nylon 12, nylon 610, nylon 612, nylon 6/66 copolymer, and nylon 6/66/610 copolymer. Polyamide resins such as coalescence, nylon MXD6, nylon 6T, nylon 6 / 6T copolymer; polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, poly Polyester resins such as arylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyester, polyoxyalkylene diimidic acid / polybutyrate terephthalate copolymer; polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile Polystyrene resins such as styrene / styrene copolymer (AS), methacrylonitrile / styrene copolymer, methacrylonitrile / styrene / butadiene copolymer; cellulose resins such as cellulose acetate and cellulose acetate butyrate; polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), fluorine resins such as tetrafluoroethylene / ethylene copolymer (ETFE); imide resins such as aromatic polyimide (PI); ethylene A vinyl alcohol copolymer (EVOH) is mentioned, These can be used individually or in combination of 2 or more types, respectively.

  Butyl rubber (IIR) is used as the rubber component constituting the dispersed phase. Further, the rubber component may contain other rubber components as long as the effects of the present invention are not impaired. Examples of such rubber components include natural rubber (NR), epoxidized natural rubber (ENR), isoprene rubber (IR), styrene butadiene rubber (SBR), nitrile rubber (NBR), and hydrogenated nitrile rubber (H- NBR), diene rubbers such as hydrogenated styrene butadiene rubber and hydrogenated rubbers thereof; olefin rubbers such as ethylene propylene rubber (EPDM), maleic acid modified ethylene propylene rubber, maleic acid modified ethylene butylene rubber, and acrylic rubber (ACM) Halogen-containing rubber such as chloroprene rubber (CR); other examples include silicon rubber, fluorine rubber, polysulfide rubber, and the like.

  The content of butyl rubber (IIR) in the rubber component constituting the dispersed phase is preferably 80% by mass or more and less than 100% by mass, and more preferably 90% by mass or more and less than 100% by mass.

  The content ratio of the thermoplastic resin and the rubber component (ratio as the polymer component excluding the components such as the filler) varies depending on the type of the thermoplastic resin, and is not particularly limited, but the mass ratio (thermoplastic resin / The rubber component) is usually preferably about 60/40 to 25/75, more preferably 50/50 to 30/70.

  The rubber component constituting the dispersed phase preferably contains 1 to 10 parts by mass of chlorosulfonated polyethylene (CSM) with respect to 100 parts by mass of butyl rubber, and contains 3 to 10 parts by mass. Is more preferable, and it is further more preferable to contain 5-10 mass parts. The chlorosulfonated polyethylene may be previously kneaded with butyl rubber before the melt-kneading of the thermoplastic resin and the rubber component, or may be added during the melt-kneading of the thermoplastic resin and the rubber component.

  Various components generally added to the rubber composition such as a crosslinking agent, zinc white, stearic acid, a filler, a softening agent, and an antioxidant can be appropriately added to the rubber component constituting the dispersed phase. That is, the rubber component constituting the dispersed phase may be a rubber composition obtained by adding various components to butyl rubber.

  Examples of the crosslinking agent for crosslinking the rubber component include vulcanizing agents such as sulfur and sulfur-containing compounds, vulcanization accelerators, and phenolic resins. From the viewpoint of heat resistance, it is preferable to use a phenolic resin. Examples of the phenolic resin include a resin obtained by a condensation reaction of phenols and formaldehyde, and an alkylphenol-formaldehyde condensate or a brominated alkylphenol-formaldehyde condensate is more preferable.

  Although content of a crosslinking agent will not be specifically limited if a rubber component can be bridge | crosslinked appropriately, and it changes also with the kind, As a standard, it is about 0.1-5 mass parts with respect to 100 mass parts of butyl rubber.

  Note that sulfur as a crosslinking agent is not essential, and as a crosslinking system, only a vulcanization accelerator or a phenol-based resin may be blended. When using the thermoplastic elastomer composition according to the present embodiment as an air permeable film for tires, it is preferable to co-crosslink at the time of vulcanization molding of a rubber member or a rubber layer as a bonded member, This is because the crosslinking of the rubber component proceeds too much due to the temperature at which the air permeation resistant film is produced, and the above-mentioned co-crosslinking becomes difficult.

  The various components optionally added to the rubber component may be added to the rubber component in advance, or may be added during the melt-kneading of the thermoplastic resin and the rubber component. In particular, it is preferable to add a vulcanized component such as a vulcanization accelerator at the final stage of melt-kneading so that the rubber component is not cross-linked as much as possible. Dynamic crosslinking may be performed in the melt-kneading stage. However, if the rubber component is too crosslinked, it is difficult to co-crosslink as described above during vulcanization molding of the member to be bonded. It is preferable to set the heating time and temperature so as not to occur.

  Further, it is preferable that the rubber component does not substantially contain a plasticizer. Here, “substantially free” means a content in a range where no significant effect is observed depending on the content, and it varies depending on the type of plasticizer, etc., but usually in 100 parts by mass of butyl rubber. On the other hand, it is less than 1 part by mass and preferably less than 0.1 part by mass.

  Plasticizers include dibutyl phthalate, dioctyl phthalate, dioctyl adipate, dibutyl glycol adipate, dibutyl carbitol adipate, dioctyl sebacate, tricresyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, trioctyl phosphate, tributoxydiethyl phosphate, butyl Examples thereof include benzenesulfonamide.

  The thermoplastic elastomer composition according to the present embodiment may be obtained by mixing a compatibilizer together with a thermoplastic resin and a rubber component. By blending the compatibilizing agent, the interfacial tension between the thermoplastic resin and the rubber component can be reduced, and the dispersed phase having a sea-island structure can be made finer. As a compatibilizing agent, as one embodiment, an ethylene-glycidyl (meth) acrylate copolymer (that is, an ethylene-glycidyl methacrylate copolymer and / or an ethylene-glycidyl acrylate copolymer) may be used. Although content of this compatibilizing agent is not specifically limited, It can be 0.5-10 mass parts with respect to 100 mass parts of butyl rubber.

  Moreover, when applying the thermoplastic elastomer composition according to the present embodiment to an air permeable film for tires, a resorcin-based formaldehyde condensate may be contained as an adhesion improver. The adhesion improver is blended in order to improve the adhesion between the air permeable resistant film and the adjacent rubber member in the tire. As the resorcin-based formaldehyde condensate, a compound obtained by condensing a phenol compound containing at least a part of resorcin and formaldehyde is used. Preferably, a resorcin-alkylphenol-formaldehyde cocondensate or a modified resorcin-formaldehyde resin is used. As a modified resorcinol-formaldehyde resin, an unsaturated group-containing monomer is bonded to at least a part of a phenol compound constituting a skeleton to form a side chain of an arylalkyl group (aralkyl group) or a graft polymer chain. Or a polymer of an unsaturated group-containing monomer or a copolymer of resorcin and the like. Moreover, you may partially contain aldehyde compounds other than formaldehyde. For example, at least one selected from styrene, α-methylstyrene, p-methylstyrene, α-chlorostyrene, divinylbenzene, vinylnaphthalene, indene, and vinyltoluene (particularly preferably styrene) coexists with resorcin and formaldehyde. It may be a reaction product obtained by mixing a small amount of butyraldehyde or other aldehyde. Although content of a resorcinol formaldehyde condensate is not specifically limited, It can be set as 1-10 mass parts with respect to 100 mass parts of butyl rubber.

  The thermoplastic elastomer composition according to the embodiment is not limited to this, but can be obtained by melt-kneading a thermoplastic resin and a rubber component together with a crosslinking agent and dynamically crosslinking the rubber with the crosslinking agent. Thus, by dynamically crosslinking the rubber component, the particle size of the dispersed phase can be reduced and the flexibility can be improved. Containing components such as a crosslinking agent may be added during the kneading, or may be mixed in advance before kneading. The kneader used for kneading is not particularly limited, and examples thereof include a twin screw extruder, a screw extruder, a kneader, and a Banbury mixer. The melt-kneading conditions are not particularly limited. For example, the kneading can be performed at 200 to 250 ° C. at a rotation speed of 100 to 300 rpm for 1 to 3 minutes. The particle size of the dispersed phase of the thermoplastic elastomer composition is not particularly limited, but is preferably from 0.1 to 2 μm, more preferably from 0.1 to 1 μm in terms of average particle diameter.

  As one embodiment, a rubber master batch pellet is prepared by adding a crosslinking agent and CSM to a rubber component, and the pellet is put into a kneader together with a thermoplastic resin and a compatibilizer, and melt kneaded to dynamically You may obtain the pellet of a thermoplastic elastomer composition by bridge | crosslinking. Also, the thermoplastic elastomer composition pellets can be obtained by adding thermoplastic resin, rubber component, cross-linking agent, CSM and compatibilizer into the kneader without pre-mixing, melt-kneading and dynamic cross-linking. Good. The adhesion improver may be added at the same time as the rubber component, and may be before or after dynamic crosslinking. However, when a phenolic resin is added as a crosslinking agent, the adhesion improver should be added after dynamic crosslinking. Is preferred. The melt-kneading conditions in this case are not particularly limited, but for example, it is preferable to knead for 1 to 3 minutes at 200 to 250 ° C. and at a rotation speed of 100 to 300 rpm.

  Thus, the air-permeable-resistant film which concerns on embodiment of this invention is obtained by film-forming the pellet of the obtained thermoplastic elastomer composition. The method for forming a film is not particularly limited. For example, a method for forming a normal thermoplastic resin into a film, such as extrusion molding or calendar molding, can be used.

  The thickness of the air permeation-resistant film is not particularly limited because it depends on the application. For example, in the case of tires, the thickness can be 0.02 to 1.0 mm, preferably 0.05 to 0.5 mm. Preferably it is 0.05-0.3 mm.

The air permeability of the air-resistant film is also not particularly limited because it depends on the application. However, in the case of tires, it conforms to JIS K7126-1 “Plastics-Film and Sheet-Gas Permeability Test Method-Part 1: Differential Pressure Method”. Thus, it is preferable that the value measured at a test gas: air and at a test temperature: 80 ° C. is at least the same air permeation resistance as an inner liner composed of a rubber layer such as butyl rubber or halogenated butyl rubber. More preferably, it is 0.0 × 10 ¹³ fm ² / Pa · s or less.

  The air permeable resistant film according to the present embodiment is applied to various pneumatic tires such as tires for passenger cars, various automobile tires including heavy load tires such as trucks and buses, and motorcycle tires including bicycles. can do.

  FIG. 1 is a cross-sectional view of a pneumatic tire 1 according to an embodiment. As shown in the figure, a pneumatic tire 1 includes a pair of bead portions 2 that are assembled to a rim, a pair of sidewall portions 3 that extend outward from the bead portion 2 in the tire radial direction, and the pair of sidewall portions 3. It is comprised from the tread part 4 which earth | grounds to the provided road surface. A ring-shaped bead core 5 is embedded in each of the pair of bead portions 2. A carcass ply 6 using an organic fiber cord is folded around the bead core 5 and locked, and is provided between the left and right bead portions 2. Further, on the outer peripheral side of the tread portion 4 of the carcass ply 6, a belt 7 made of two belt plies using a rigid tire cord such as a steel cord or an aramid fiber is provided.

  An inner liner 8 is provided inside the carcass ply 6 over the entire inner surface of the tire. In the present embodiment, the air permeable resistant film is used as the inner liner 8. As shown in the enlarged view in FIG. 1, the inner liner 8 is bonded to the inner surface of the carcass ply 6 that is a rubber layer on the inner surface of the tire, and more specifically, a topping rubber that covers the cord of the carcass ply 6. Affixed to the inner surface of the layer.

  In the pneumatic tire according to the present embodiment, in order to prevent the cord of the carcass ply 6 from biting into the inner liner 8, a tie rubber layer is selectively disposed in a part between the layers of the carcass ply 6 and the inner liner 8. It may be done.

  As a method for manufacturing a pneumatic tire using an air permeable resistant film according to the present embodiment, for example, using an air permeable resistant film as an inner liner, an inner liner is mounted on the outer periphery of a molding drum, A carcass ply is affixed thereon, and each tire member such as a belt, tread rubber, and sidewall rubber is further affixed and inflated to produce a green tire (unvulcanized tire). A pneumatic tire is obtained by vulcanization molding. In the example shown in FIG. 1, the air permeation-resistant film is provided on the inner surface side of the carcass ply. However, the air pressure from the inside of the tire can be prevented and the air pressure of the tire can be maintained, that is, the internal pressure. As long as it is provided as an air permeation suppression layer for holding, it can be provided at various positions such as the outer surface side of the carcass ply, and is not particularly limited.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

  In accordance with the composition (parts by mass) shown in Table 1, dry blending of a thermoplastic resin and a compatibilizer in advance and other components other than the rubber component, chlorosulfonated polyethylene, and the adhesion improver were dry mixed. This was melt kneaded using a twin screw extruder (Plastic Industries Laboratory) at a temperature of 220 ° C. and dynamically crosslinked to obtain pellets of a thermoplastic elastomer composition. The obtained pellets were again put into a twin screw extruder together with an adhesion improver, kneaded at a temperature of 220 ° C., then molded into a width of 14 cm and a thickness of 0.2 mm using a single screw extruder, A sample was obtained.

The details of each component in Table 1 are as follows.
<Thermoplastic elastomer composition>
IIR: “IIR268” manufactured by ExxonMobil Chemical
・ Nylon 6/66: “Novamid 2020J” manufactured by DSM
・ Chlorosulfonated polyethylene 1: “TS-320” manufactured by Tosoh Corporation
・ Chlorosulfonated polyethylene 2: “TS-530” manufactured by Tosoh Corporation
・ Chloroprene rubber: “B-15” manufactured by Tosoh Corporation
・ Plasticizer: “BM-4” manufactured by Daihachi Chemical Industry Co., Ltd.
・ Crosslinking agent: “Tacchi Roll 250-III” manufactured by Taoka Chemical Industries
・ Zinc flower: "Zinc flower No. 1" manufactured by Mitsui Mining & Smelting Co., Ltd.
・ Stearic acid: “Lunac S-20” manufactured by Kao Corporation
・ Compatibilizer: “Bond First E” manufactured by Sumitomo Chemical Co., Ltd.
-Adhesion improver: "Sumikanol 620" manufactured by Taoka Chemical Industry Co., Ltd.

<Rubber composition for adhesion evaluation>
・ NR: RSS # 3
・ SBR: “JSR1502” manufactured by JSR Corporation
Carbon black: “Showa Black N-330T” manufactured by Cabot Japan
・ Stearic acid: “Lunac S-20” manufactured by Kao Corporation
・ Zinc flower: "Zinc flower No. 1" manufactured by Mitsui Mining & Smelting Co., Ltd.
・ Sulfur: “Powder sulfur” manufactured by Tsurumi Chemical Co., Ltd.
・ Vulcanization accelerator: “Noxeller NS-P” manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.
Melamine derivative: Hexamethoxymethylmelamine, “CYRETS 963L” manufactured by Nippon Cytec Industries, Ltd.

  About each sample which consists of the obtained thermoplastic elastomer composition, workability (melt viscosity), air permeability, a softness | flexibility (10% tensile stress), and adhesiveness were evaluated. Each evaluation method is as follows.

Processability (melt viscosity): Using a capillary rheometer manufactured by Yasuda Seiki Seisakusho, the melt viscosity at 230 ° C. and a shear rate of 800 (1 / s) was measured. The index was displayed. A larger index indicates a higher melt viscosity and inferior processability.

Air permeability: According to JIS K7126-1 “Plastics—Films and sheets—Gas permeability test method—Part 1: Differential pressure method” Test gas: Air, Test temperature: Value measured at 80 ° C. is there. The smaller this value, the better the air permeation resistance.

-Flexibility (10% tensile stress): Measured according to the tensile test of JIS K6251. The dumbbell shape was No. 3 (thickness was 200 μm), and the stress in the state of 10% elongation when pulled at a speed of 500 mm / min was measured to determine the median value in the extrusion direction of the film. The smaller this value, the better the flexibility.

Adhesiveness: A rubber composition for adhesion evaluation having a thickness of 0.3 mm, prepared according to the formulation (parts by mass) described in Table 2, is used as a tie rubber layer on the surface of the unvulcanized topping rubber layer of the carcass ply. Pasted. Each sample consisting of a resin film with a thickness of 0.2 mm is overlapped with a tie rubber layer affixed to the carcass ply, the press temperature is 160 ° C., the press time is 20 minutes, the press pressure is 30 kg / cm ^2, and press vulcanization is performed. Implemented and integrated the adhesive. The obtained vulcanized adhesive was cut into a 25 mm width strip and subjected to a 180 ° peel test at a peel rate of 50 mm / min. The average value between 8 cm was defined as the adhesive strength.

An evaluation result is as showing in Table 1, and the value of the air permeability of each example and a comparative example is 5.0 * 10 < ¹³ > fm < ² > / Pa * s or less, and has the outstanding air permeability resistance. It was confirmed. In addition, Examples 1 to 3 using chlorosulfonated polyethylene were improved in processability, flexibility and adhesiveness as compared with Comparative Examples 1 to 4.

  From the comparison between Comparative Example 1 and Comparative Example 2, it was confirmed that the air permeation resistance and the adhesiveness deteriorated by containing a plasticizer.

  Further, from the comparison between Comparative Example 1 and Comparative Examples 3 and 4, it was confirmed that the adhesiveness deteriorated when chloroprene of a halogenated rubber different from chlorosulfonated polyethylene was used.

  The thermoplastic elastomer composition of the present invention can be used for an inner liner of various tires such as passenger cars, light trucks, and buses.

DESCRIPTION OF SYMBOLS 1 ... Pneumatic tire 2 ... Bead 3 ... Side wall 4 ... Tread 5 ... Bead core 6 ... Carcass ply 7 ... Belt 8 ... Inner liner

Claims (3)

A continuous phase composed of a thermoplastic resin and a dispersed phase composed of vulcanized rubber dispersed in the continuous phase;
A thermoplastic elastomer composition, wherein the vulcanized rubber contains 1 to 10 parts by mass of chlorosulfonated polyethylene with respect to 100 parts by mass of butyl rubber.   An air-permeable film for tire, comprising the thermoplastic elastomer composition according to claim 1. A pneumatic tire using the air-permeable film for tires according to claim 2.

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