JP5838046B2 - tire - Google Patents

Description

  The present invention relates to a tire in which a multilayer film is disposed on at least a part of a tire sidewall.

In general, improving the appearance of a pneumatic tire, particularly the appearance of the side portion, is important for increasing the commercial value of the pneumatic tire, and various proposals have been made.
For example, it is disclosed to prevent discoloration over time by blending a specific ultraviolet absorber together with a diamine-based anti-aging agent into a rubber composition constituting a tire body such as a tread portion or a side portion. (For example, refer to Patent Document 1). Also disclosed is a surface-protecting glazing agent that imparts gloss by being applied to the surface of a product tire (see, for example, Patent Document 2).

  From the viewpoint of imparting the function of improving the weather resistance as well as the appearance of the tire, a pneumatic tire is proposed in which a nylon film layer is provided outside the sidewall rubber layer (see, for example, Patent Document 3). Furthermore, a pneumatic tire in which a thin film made of ultrahigh molecular weight polyethylene is laminated on the sidewall surface has been proposed from the viewpoint of improving appearance while imparting ozone crack resistance (see, for example, Patent Document 4). .

  On the other hand, in combination with recent user's tendency of multi-preference, personalization, and luxury, for example, even if the color is taken as an example, the color changes depending on the viewing direction or has a higher chroma An elegant and high-quality texture has been demanded. Therefore, structures that produce colors by actively using physical phenomena such as light reflection / interference, diffraction, scattering, etc. without using dyes such as dyes and pigments, or coloration by those physical phenomena and conventional dyes and pigments, etc. Studies have been made on structures that combine the color development by, and produce a more vivid color due to the synergistic effect of both (see, for example, Patent Document 5).

JP 2006-143889 A JP 2002-241705 A Japanese Patent Application Laid-Open No. 07-096719 Japanese Patent Laid-Open No. 03-292205 JP-A-11-127434

However, for example, the tires disclosed in Patent Documents 3 and 4 are not sufficient from the viewpoint of diversifying the appearance design in recent years. In addition, the mere thermoplastic resin films disclosed in these patent documents have poor flexibility and are difficult to stretch, so it is difficult to sufficiently follow the expansion and subsequent contraction of the tire body during tire vulcanization. There was a problem that wrinkles entered and tired at the tire manufacturing stage.
Further, since the color developing structure disclosed in Patent Document 5 is used for paints for automobile painting, etc., it is suitable as an application formed as a coating film on a hard and smooth surface. When used in the above, there was a problem similar to the above.

  The present invention has been made in view of such a situation, and improves the appearance by changing the reflection of light on the surface of the tire side portion, and provides a tire having excellent design properties, and changes in tire distortion. An object of the present invention is to provide a tire that can be confirmed by hue and has excellent daily manageability.

As a result of intensive studies to achieve the above object, the present inventors have found that the object can be achieved by disposing a multilayer film having specific optical characteristics on at least a part of the outer surface of the tire sidewall. I found it.
The present invention has been completed based on such findings.

That is, the present invention
[1] A tire in which a multilayer film is disposed on at least a part of the outer surface of a tire sidewall,
The multilayer film has an optical layer composed of a plurality of thin layers in which thin layers having a refractive index difference between adjacent layers of 0.01 or more are alternately stacked, and the average thickness of the thin layers is 0.01 μm or more and 0.0. A tire of 5 μm or less,
[2] The tire according to claim 1, wherein Young's modulus (JIS K7161-1994) at 23 ° C. of at least one of the plurality of thin layers is 0.1 MPa or more and 500 MPa or less.
[3] The tire according to [1] or [2], wherein the optical layer is formed by laminating three or more thin layers,
[4] The tire according to any one of [1] to [3], wherein the multilayer film is formed by a co-extrusion step.
[5] The tire according to any one of [1] to [4], wherein at least one of the plurality of thin layers is made of a resin composition containing a thermoplastic elastomer.
[6] The thermoplastic elastomer is a polystyrene-based thermoplastic elastomer, a polyolefin-based thermoplastic elastomer, a polydiene-based thermoplastic elastomer, a polyurethane-based thermoplastic elastomer, a polyester-based thermoplastic elastomer, a polyamide-based thermoplastic elastomer, or a silicone-based thermoplastic elastomer. The tire according to [5], which is at least one selected from
[7] The tire according to any one of [1] to [6], wherein a thin layer having a higher refractive index in an adjacent layer of the plurality of thin layers includes at least one of metal fine particles and metal oxide fine particles. And [8] The tire according to any one of [1] to [7], wherein the thin layer having a lower refractive index in the adjacent layer among the plurality of thin layers includes hollow fine particles,
Is to provide.

  According to the present invention, the appearance is improved by changing the reflection of light on the surface of the tire side portion, and a tire having excellent design properties is provided. An excellent tire can be provided.

It is typical sectional drawing which shows an example of the structure of the multilayer film in this invention. It is typical sectional drawing which shows another example of the structure of the multilayer film in this invention. It is a schematic fragmentary sectional view which shows an example of the structure of the tire of this invention.

Hereinafter, the tire according to the present invention will be described in detail.
The tire of the present invention is a tire in which a multilayer film is disposed on at least a part of a tire sidewall, and the multilayer film is formed by alternately laminating thin layers having a refractive index difference between adjacent layers of 0.01 or more. It has an optical layer composed of a plurality of thin layers, and the average thickness of the thin layers is 0.01 μm or more and 0.5 μm or less.

<Multilayer film>
First, the multilayer film in this invention is demonstrated.
The multilayer film in the present invention has an optical layer composed of a plurality of thin layers in which thin layers having a refractive index difference between adjacent layers of 0.01 or more are alternately laminated. An optical layer composed of alternately laminated thin layers having different refractive indexes interferes and develops the color of the wavelength in the visible light region by the reflection / interference action of natural light. The color development is as bright as metallic luster, exhibits a pure and clear color (single color) of a specific wavelength, and is completely different from color development due to light absorption of dyes and pigments. The optical interference effect is greatly influenced by the difference in refractive index between adjacent thin layers, the optical distance of each layer (refractive index × thickness of each layer), and the number of stacked layers. Among them, in order to obtain an excellent optical interference effect. In particular, the refractive index difference between the thin layers is an important factor.

In the present invention, the difference in refractive index between the adjacent thin layers needs to be 0.01 or more. If the difference in refractive index is less than 0.01, it is necessary to increase the number of laminated layers to obtain a high refractive index, and in practical manufacturing conditions, it cannot be recognized as a color by human eyes. is there.
The refractive index difference between the adjacent thin layers is preferably 0.02 or more, and more preferably 0.03 or more. The upper limit of the refractive index difference is about 1.0.

The structure of the multilayer film in this invention is demonstrated using FIG.1 and FIG.2. 1 and 2 each schematically show a cross-sectional shape of the multilayer film according to the present invention cut at a right angle on a plane perpendicular to the film surface.
FIG. 1 shows a cross-sectional shape of a multilayer structure portion 10 (optical layer) formed by alternately laminating thin layers A and thin layers B. Moreover, the multilayer film in this invention should just have an optical layer, for example, as shown in FIG. 2, the thing by which the protective layer part 20 was provided in the outer periphery of the multilayer structure part 10 may be used. 1 and 2, a large number of thin layers A and thin layers B are alternately laminated in parallel with the major axis direction (horizontal direction in the drawing) of the film surface. As shown in FIGS. 1 and 2, the optical layer having an optical interference function according to the present invention has thin layers A and thin layers B alternately laminated in parallel to the major axis direction of the film surface. The area effective for optical interference is wide. For the optical interference function, the parallelism of the alternate lamination is particularly important.

In the cross section of the multilayer film, the average thickness of each layer in the thin multilayer structure 10 needs to be 0.01 μm or more and 0.5 μm or less. If the average thickness is less than 0.01 μm, the expected interference effect cannot be obtained. On the other hand, if the average thickness exceeds 0.5 μm, the expected interference effect cannot be obtained. The average thickness of the thin layer is preferably 0.01 μm or more and 0.4 μm or less, and more preferably 0.05 μm or more and 0.15 μm or less.
Further, when the optical distances in the thin layer A and the thin layer B, that is, the product of the layer thickness and the refractive index are equal, a higher interference effect can be obtained. In particular, the maximum interference color is obtained when twice the sum of the two optical distances equal to the primary reflection is equal to the wavelength distance of the desired color.

In the multilayer film of the present invention having the above-described configuration, the optical distance of the alternately laminated layers (refractive index of each thin layer × thickness of each thin layer) is in the major axis direction and minor axis direction of the film cross section. As a result, the half-value width λ _{l = 1/2} of the reflection spectrum of the multilayer film converges in the range of 0 nm <λ _{l = 1/2} <200 nm. When the half-value width of the reflection spectrum exceeds 200 nm, the multilayer film develops multiple colors and offsets each other, so that the color development cannot be visually recognized with the naked eye.

Here, the reflection spectrum of the multilayer film in the case of 0 degree incidence / 0 degree light reception will be described as an example. The emission peak wavelength in this case is related to the optical distance (= thickness) of the layers of the multilayer structure 10, and the emission intensity (relative reflectance when using a reference white plate) is the multilayer structure. This is related to the number of thin layers stacked in the portion 10. That is, the reflection spectrum represents an aggregate distribution that satisfies a certain optical distance. Therefore, when the full width at half maximum of the peak wavelength is wide, not only multiple color development is observed, but also the color development intensity is weakened, so that an excellent interference effect cannot be obtained. In the case of coloration in the entire visible light region, the coloration is white and the color development cannot be visually recognized with the naked eye. However, in the case of the multilayer structure portion 10, the total number of layers having an optical distance (thickness) that develops a certain wavelength decreases. As a result, the color intensity (relative reflectance) is also weakened.
From the above viewpoint, the multilayer structure 10 (optical layer) is preferably formed by stacking five or more thin layers, and more preferably by stacking seven or more layers.

In addition, the multilayer film in the present invention is provided on the tire sidewall as will be described later. On the sidewall surface, which is usually black, a multilayer film having brightness like a metallic luster and having a clear color is provided. In this case, it is desirable from the design consideration of the entire tire that the black color of the sidewall surface can be confirmed to some extent when the tire is viewed from at least the direction perpendicular to the film surface. From this viewpoint, the total light transmittance in the multilayer film is 30% or more. It is preferable that it is 50% or more.
The total light transmittance of the multilayer film is measured by measuring the total light transmittance in the thickness direction of the multilayer film using a fully automatic direct reading haze computer HGM-2DP (manufactured by Suga Test Instruments Co., Ltd.). Is called.

Next, specific embodiments of the multilayer structure (optical layer in the present invention) will be further described.
The multilayer structure includes, for example, a thermoplastic resin film (A layer) and a layer (B layer) made of a resin composition containing an elastomer. Thereby, while being able to maintain the color development intensity in the said multilayer film and the intensity | strength as a film, by having B layer with high ductility, a multilayer film will have flexibility as a whole, and the follow-up of the distortion change in a tire And excellent crack resistance and the like.

  From this viewpoint and the manufacturing viewpoint, the total number of layers A and B is preferably 5 or more, more preferably 7 or more, still more preferably 17 or more, particularly preferably 25 or more, 48 layers or more are particularly preferable, and 65 layers or more are very preferable. The multilayer structure may be a multilayer structure, and the total number of layers A and B may be 128 or more, 256 or more, 512 or more, or 1,024 or more. The upper limit of the total number of layers is appropriately selected depending on the manufacturing cost of the multilayer structure.

  As the stacking order of the A layer and the B layer, it is necessary that the A layer and the B layer are alternately stacked. By irradiating active energy rays to the laminate in which the A layers and the B layers are alternately laminated in this manner, the connectivity between the laminated layers can be improved and high adhesiveness can be expressed. As a result, the interlayer adhesion of the multilayer structure, as well as the color developability and the bending resistance can be significantly improved. Moreover, since A layer is pinched | interposed into B layer from both surfaces by laminating | stacking A layer and B layer alternately, the ductility of A layer is improved more.

  Further, in this multilayer structure, support layers may be laminated on both surfaces or one surface of a laminate composed of such an A layer and a B layer. The support layer is not particularly limited, and for example, a general synthetic resin layer, a synthetic resin film, or the like is also used. Further, a part of the A layer or the B layer can be thickened as necessary.

  In this multilayer structure, since the B layer made of the resin composition containing the elastomer is laminated together with the A layer made of the thermoplastic resin film, for example, the ductility is low in order to adjust the refractive index difference as the A layer. Even when a thermoplastic resin film is used, the ductility of the A layer made of the resin composition having low ductility can be further increased. This is presumably because the resin layer having low ductility is transferred to a highly ductile state by thinly laminating the layer A made of the resin composition having low ductility on the layer B having excellent ductility. In the present invention, paying attention to the above facts, even when the layer A is made of a material having low ductility, the color developability required for the multilayer film in the present invention can be obtained by reducing the thickness of each layer in this way. And bending resistance (flexibility) have been found to be highly compatible.

From the above viewpoint, in the multilayer film used in the present invention, the Young's modulus (JIS K7161-1994) at 23 ° C. of at least one of the thin layers is 0.1 MPa or more and 500 MPa or less. Is preferred. Thus, by including a thin layer with a low Young's modulus in a plurality of thin layers constituting the multilayer structure, it is possible to more effectively provide flexibility when attaching to a tire and bending resistance against strain during use. Can be expressed. As the low Young's modulus thin layer, B layer made of a resin composition containing an elastomer is suitable.
The Young's modulus at 23 ° C. of the specific thin layer is more preferably from 0.1 MPa to 100 MPa.

  In addition, the structure of a multilayer structure is not only a structure provided with the said thermoplastic resin film (A layer) and the layer (B layer) which consists of a resin composition containing an elastomer, but the refractive index difference between A layer and B layer is also shown. If the configuration is 0.01 or more, for example, it is a multilayer structure in which only layers made of a resin composition containing an elastomer are laminated (a layer made of a resin composition containing both an A layer and a B layer). May be. That is, in the present invention, in order to ensure flexibility in the multilayer film, it is preferable that at least one of a plurality of thin layers constituting the multilayer structure is made of a resin composition containing an elastomer.

  Furthermore, in the present invention, since the multilayer film is flexible as described above, when it is disposed on the tire sidewall, the film will be deformed following the change in tire distortion, and accordingly the multilayer film will be deformed. Since the angle of the light incident on and the angle of the reflected light change, the wavelength (that is, the color) of the reflected light changes. Therefore, for example, a strain change due to a decrease in the internal pressure of the tire can be confirmed by the color of the tire side surface, and can be effectively used for daily management of the tire.

  The upper and lower limits of the average thickness of the single layer A and the single layer B are as described above. However, if the average thickness is smaller than the lower limit, it becomes difficult to mold with a uniform thickness, and color development of the multilayer structure is caused. And its flexibility may be reduced. On the other hand, when the average thickness exceeds the upper limit, when the thickness of the entire multilayer structure is the same, the color developability and crack resistance of the multilayer structure may be reduced. The average thickness of one A layer and one B layer is a value obtained by dividing the total thickness of all A layers and all B layers contained in the multilayer structure by the number of layers A and B, respectively. .

  Regarding the average thickness of the B layer, the ratio of the average thickness of the B layer to the average thickness of the A layer (B layer / A layer) is 1 or more, that is, the average thickness of the B layer is the average of the A layer. The thickness is more preferably equal to or greater than the thickness, and particularly preferably 2 or more. By making the ratio of the thicknesses of the A layer and the B layer in this way, the bending fatigue characteristics until the multilayer structure reaches the entire layer breakage is improved.

  The thickness of the multilayer structure is preferably 0.1 μm or more and 1,000 μm or less, more preferably 0.5 μm or more and 750 μm or less, and further preferably 1 μm or more and 500 μm or less. By setting the thickness of the multilayer structure within the above range, the average thickness of one layer of the A layer and the B layer is combined with the above range, and the applicability of the multilayer film having this to the sidewall portion of the tire is applied. The color developability, flex resistance, crack resistance, durability, stretchability and the like can be further improved while maintaining the above. Here, the thickness of the multilayer structure is obtained by measuring the thickness of the cross section at an arbitrarily selected point of the multilayer structure.

Below, the said thermoplastic resin and elastomer which can be applied to this invention are demonstrated.
The thermoplastic resin is not particularly limited as long as the refractive index difference between adjacent layers in the formed multilayer structure can be 0.01 or more, and various materials can be used. As such a thermoplastic resin, for example, at least one selected from polyamide resins, vinylidene chloride resins, polyester resins, fluorine resins, acrylic resins, and vinyl resins can be used. Among these thermoplastic resins, polyamide-based resins are preferable from the viewpoints of refractive index selectivity, film-forming properties, mechanical strength, and the like.

(Polyamide resin)
Examples of the polyamide resin include aliphatic polyamide homopolymers such as nylon-6, nylon-11, nylon-12, nylon-6,6, nylon-6,10; nylon-6 / 12, nylon-6 / 11, Nylon-6 / 9, Nylon-6 / 6,6, Nylon-6 / 6,6 / 6,12 and other aliphatic polyamide copolymers; polymetaxylylene adipamide (MX-nylon), hexa Aromatic polyamides such as methylene terephthalamide / hexamethylene isophthalamide copolymer (nylon-6T / 6I) can be mentioned. These polyamide resins can be used alone or in combination of two or more. Among these, nylon-6 and nylon-6,6 are preferable.

(Vinylidene chloride resin)
The vinylidene chloride resin may be polyvinylidene chloride, but usually a vinylidene chloride copolymer can be suitably used. The vinylidene chloride copolymer is a copolymer of vinylidene chloride and a copolymerizable monomer. Examples of such a copolymerizable monomer include vinyl halides (such as vinyl chloride) and carboxylic acid vinyl esters (for example, , Vinyl acetate, etc.), unsaturated carboxylic acids (eg, (meth) acrylic acid, crotonic acid, etc.), (meth) acrylic acid esters (eg, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate) , Tert-butyl acrylate, pentyl acrylate, hexyl acrylate and the like (meth) acrylic acid alkyl (for example, (meth) acrylic acid C _1-10 alkyl ester), (meth) acrylonitrile and the like.

(Polyester resin)
Examples of the polyester resin include polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), Examples thereof include aromatic polyesters such as liquid crystal polyester, polybutylene terephthalate-polytetramethylene glycol copolymer, and polyoxyalkylene diimide diacid-polybutylene terephthalate copolymer.

(Fluorine resin, acrylic resin, vinyl resin)
Examples of the fluororesin include polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), and tetrafluoroethylene / ethylene copolymer (ETFE).
Examples of the acrylic resin include poly (meth) acrylate resins such as polymethyl methacrylate (PMMA) and polyethyl methacrylate, polyacrylonitrile, and the like.
Examples of the vinyl resin include vinyl acetate (EVA), polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer resin (EVOH), polyvinylidene chloride (PDVC), polyvinyl chloride (PVC), and vinyl chloride-chloride. Examples thereof include vinylidene copolymer resins and vinylidene chloride-methyl acrylate copolymer resins.

  Moreover, the thin layer which comprises the multilayer structure in this invention may contain the layer which has gas barrier property. As the resin constituting the layer having gas barrier properties, ethylene-vinyl alcohol copolymer resin, polyamide resin, and polyester resin are preferable. In addition to gas barrier properties, ethylene is used from the viewpoints of melt moldability, adhesion to the B layer, and the like. -Vinyl alcohol copolymer resins are particularly preferred.

When the film (A layer) made of a thermoplastic resin has gas barrier properties, the oxygen permeability coefficient at 20 ° C. and 65% RH is preferably 3.0 × 10 ⁻¹⁰ cm ³ / cm ² · sec · cmHg or less. 1.0 × 10 ⁻¹⁰ cm ³ / cm ² · sec · cmHg or less, and more preferably 5.0 × 10 ⁻¹¹ cm ³ / cm ² · sec · cmHg or less. When the oxygen permeability coefficient at 20 ° C. and 65% RH exceeds 3.0 × 10 ⁻¹⁰ cm ³ / cm ² · sec · cmHg, when this thermoplastic resin film (A layer) is used as a gas barrier layer, In order to enhance the internal pressure retention characteristics, the thermoplastic resin film (A layer) must be thickened, and the weight of the tire may not be sufficiently reduced.

As the thermoplastic resin used in the present invention, a flexible resin (A2) having a storage shear modulus G ′ at −20 ° C. lower than that of the thermoplastic resin (A1) is dispersed in a matrix made of the thermoplastic resin (A1). You may use the made resin composition.
The flexible resin (A2) preferably has a functional group that reacts with a hydroxyl group. When the flexible resin (A2) has a functional group that reacts with a hydroxyl group, the flexible resin (A2) is uniformly dispersed in the thermoplastic resin (A1). Here, examples of the functional group that reacts with a hydroxyl group include a maleic anhydride residue, a hydroxyl group, a carboxyl group, and an amino group. Specific examples of the flexible resin (A2) having a functional group that reacts with a hydroxyl group include maleic anhydride-modified hydrogenated styrene-ethylene-butadiene-styrene block copolymer, maleic anhydride-modified ultra-low density polyethylene, and the like. It is done.

  In addition, the thermoplastic resin used in the present invention is within a range that does not impair the object of the present invention, and if necessary, other resins, or the radical crosslinking agent, the thermal stabilizer, the ultraviolet absorber, the antioxidant, It may be a resin composition containing various additives such as a colorant, a filler, and sulfur. When the resin composition of the thermoplastic resin contains an additive, the amount thereof is preferably 50% by mass or less, more preferably 30% by mass or less, and more preferably 10% by mass or less based on the total amount of the resin composition. It is particularly preferred that

Next, there is no restriction | limiting in particular as an elastomer which can be used for this invention, It selects suitably from conventionally well-known thermoplastic elastomers.
Examples of the thermoplastic elastomer include polystyrene thermoplastic elastomers, polyolefin thermoplastic elastomers, polydiene thermoplastic elastomers, polyvinyl chloride thermoplastic elastomers, chlorinated polyethylene thermoplastic elastomers, polyurethane thermoplastic elastomers (hereinafter referred to as thermoplastic elastomers). , Sometimes referred to as “TPU”), at least one selected from the group consisting of polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and fluororesin-based thermoplastic elastomers. Among these, from the viewpoint of ease of molding, polystyrene-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polydiene-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and silicone-based elastomers At least one selected from the group consisting of is preferably used.

(Polystyrene thermoplastic elastomer)
The polystyrene-based plasticizing elastomer has an aromatic vinyl polymer block (hard segment) and a rubber block (soft segment), and the aromatic vinyl polymer portion forms a physical cross-link and becomes a crosslinking point. On the other hand, the rubber block imparts rubber elasticity.
This polystyrene-based thermoplastic elastomer is, for example, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isobutylene-styrene, depending on the arrangement pattern of the soft segments therein. Block copolymer (SIBS), styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-ethylene / propylene-styrene block copolymer (SEPS), and polybutadiene and butadiene-styrene random copolymer A block copolymer of crystalline polyethylene and ethylene / butylene-styrene random copolymer obtained by hydrogenating a block copolymer of the above, a block copolymer of polybutadiene or ethylene-butadiene random copolymer and polystyrene. Obtained by hydrogenating a click copolymers include, for example, di-block copolymer of crystalline polyethylene and polystyrene.
Among these, styrene-isobutylene-styrene block copolymer (SIBS), styrene- from the viewpoint of balance such as mechanical strength, heat stability, weather resistance, chemical resistance, gas barrier properties, flexibility, and workability. Ethylene / butylene-styrene block copolymers (SEBS) and styrene-ethylene / propylene-styrene block copolymers (SEPS) are preferred.

(Polyolefin thermoplastic elastomer)
Examples of the polyolefin-based thermoplastic elastomer include a thermoplastic elastomer using a polyolefin such as polypropylene or polyethylene as a hard segment and an ethylene-propylene-diene copolymer rubber as a soft segment. There are blended and implantable types. Mention may also be made of maleic anhydride-modified ethylene-butene-1 copolymer, maleic anhydride-modified ethylene-propylene copolymer, halogenated butyl rubber, modified polypropylene, modified polyethylene and the like.

(Polydiene thermoplastic elastomer)
Examples of the polydiene thermoplastic elastomer include 1,2-polybutadiene TPE, trans 1,4-polyisoprene TPE, hydrogenated conjugated diene TPE, and epoxidized natural rubber.
1,2-polybutadiene-based TPE is a polybutadiene containing 90% or more of 1,2-bonds in the molecule, and crystalline syndiotactic 1,2-polybutadiene as a hard segment and amorphous 1,2 as a soft segment. It consists of 2-polybutadiene.
On the other hand, trans 1,4-polyisoprene-based TPE has a trans 1,4 structure of 98% or more. Crystalline trans 1,4 segment as a hard segment and amorphous trans 1,4 as a soft segment. It consists of segments.

(Polyurethane thermoplastic elastomer)
The polyurethane-based thermoplastic elastomer (TPU) comprises (1) a polyurethane obtained by a reaction of a short-chain glycol and an isocyanate as a hard segment, and (2) a polyurethane obtained by a reaction of a long-chain glycol and an isocyanate as a soft segment. , A linear multi-block copolymer. Here, polyurethane is a general term for compounds having a urethane bond (—NHCOO—) obtained by a polyaddition reaction (urethanization reaction) of isocyanate (—NCO) and alcohol (—OH).
This TPU is composed of a polymer polyol, an organic polyisocyanate, a chain extender and the like. This polymer polyol is a substance having a plurality of hydroxyl groups, and can be obtained by polycondensation, addition polymerization (for example, ring-opening polymerization), polyaddition or the like. Examples of the polymer polyol include polyester polyol, polyether polyol, polycarbonate polyol, or a cocondensate thereof (for example, polyester-ether-polyol). These polymer polyols may be used alone or in combination of two or more. Among these, a polyester polyol or a polycarbonate polyol is preferable, and a polyester polyol is particularly preferable.
For example, the polyester polyol can be obtained by condensing an ester-forming derivative such as dicarboxylic acid, its ester or its anhydride and a low molecular weight polyol by direct esterification or transesterification, or by opening a lactone according to a conventional method. It can be produced by polymerization.

(Polyester thermoplastic elastomer)
In the polyester-based thermoplastic elastomer (TPEE), polyester was used as a hard segment in the molecule, and polyether or polyester having a low glass transition temperature (Tg) was used as a soft segment. It is a multi-block copolymer. TPEE has the following types depending on the difference in molecular structure, and the polyester / polyether type and the polyester / polyester type dominate.
(1) Polyester / polyether type TPEE
Generally, aromatic crystalline polyester is used as the hard segment and polyether is used as the soft segment.
(2) Polyester / Polyester type TPEE
Aromatic crystalline polyester as hard segment and aliphatic polyester as soft segment.
(3) Liquid crystalline TPEE
As a special one, there is a liquid crystal type TPEE using rigid liquid crystal molecules as hard segments and aliphatic polyester as soft segments.

(Polyamide thermoplastic elastomer)
The polyamide-based thermoplastic elastomer (TPA) is a multi-block copolymer using polyamide as a hard segment and polyether or polyester having a low Tg as a soft segment. The polyamide component is selected from nylon 6, 66, 610, 11, 12, and the like, and nylon 6 or nylon 12 is mainly used.
As the constituent material of the soft segment, a long-chain polyol of polyether diol or polyester diol is used. Representative examples of polyethers include diol poly (oxytetramethylene) glycol (PTMG), poly (oxypropylene) glycol, and the like. Representative examples of polyester diols include poly (ethylene adipate) glycol, poly (butylene-1,4 adipate) glycol, and the like.

(Silicone-based thermoplastic elastomer)
Silicone-based thermoplastic elastomers are mainly composed of organopolysiloxane and are classified into polydimethylsiloxane, polymethylphenylsiloxane, and polydiphenylsiloxane. Some are modified with vinyl groups, alkoxy groups, and the like. Specific examples include the KE series (manufactured by Shin-Etsu Chemical Co., Ltd.), SE series, CY series, SH series (above, manufactured by Toray Dow Corning Silicone Co., Ltd.) and the like.

  The resin composition constituting the elastomer layer is within a range that does not impair the object of the present invention, if necessary, a resin other than the elastomer material, or the radical crosslinking agent, heat stabilizer, ultraviolet absorber, antioxidant, and the like described above. Various additives such as colorants and fillers may be included. When the resin composition of the elastomer layer contains an additive, the amount thereof is preferably 50% by mass or less, more preferably 30% by mass or less, and more preferably 10% by mass or less with respect to the total amount of the resin composition. It is particularly preferred.

Of the adjacent thin layers in the multilayer film of the present invention, the resin constituting the thin layer having the higher refractive index preferably has a refractive index of 1.50 or more, and a refractive index of 1.55 or more. It is more preferable to have. On the other hand, the resin constituting the thin layer having a lower refractive index among the adjacent thin layers preferably has a refractive index of 1.55 or less, and has a refractive index of 1.50 or less. More preferably.
From this point of view, as a preferable combination of the thin layers (thermoplastic resin / elastomer) adjacent in the stacking direction constituting the multilayer structure which is the optical layer in the present invention, when the refractive index is n, For example, nylon 6 (n: 1.530) / EPDM (n: 1.480), styrene-butadiene-styrene rubber (n: 1.560) / acrylic rubber (n: 1.460), thiourethane (n: 1) .700) / polybutadiene (n: 1.520). Moreover, as a suitable combination of the thin layer (elastomer / elastomer) adjacent to the laminating direction constituting the multilayer structure, for example, thermoplastic urethane elastomer (n: 1.540) / EPDM (n: 1.480), chloroprene (N: 1.560) / polybutadiene (n: 1.520), polysulfide rubber (n: 1.600) / silicone rubber (n: 1.400) and the like.

Moreover, in this invention, the refractive index of the adjacent thin layer in the said multilayer film can also be adjusted by making a resin etc. which comprise a thin layer contain microparticles | fine-particles.
Specifically, when forming a thin layer having a higher refractive index among adjacent thin layers, it is preferable to contain at least one of metal fine particles and metal oxide fine particles in the resin or the like constituting the layer.

As the metal oxide fine particles, high refractive index metal oxide fine particles such as TiO ₂ , ZrO ₂ , CeO ₂ , Al ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , LaO ₂ , Ho ₂ O ₃ , ZnO, etc. And one or more of high refractive index metal fine particles such as Zr, Ti and Ce. The particle diameter of the fine particles is preferably 0.1 μm or less.
In addition, the ratio of the metal oxide fine particles and the like to the resin is such that if the amount of the metal oxide fine particles is excessively large and the resin is insufficient, the film strength of the high refractive index layer is lowered. Since the rate cannot be sufficiently increased, the ratio of the metal oxide fine particles and the like to the total of the metal oxide fine particles and the resin is preferably in the range of 10 to 60% by volume, particularly 20 to 50% by volume. .

On the other hand, when forming a thin layer having a lower refractive index among adjacent thin layers, it is preferable to contain hollow fine particles in the resin or the like constituting the layer.
Here, the hollow fine particles refer to fine particles having an outer shell layer and the inside surrounded by the outer shell layer being a porous structure or a cavity. The porous structure and the cavity contain air (refractive index: 1), and the refractive index of the layer can be reduced by containing the hollow particles in the low refractive index layer. Examples of the hollow fine particle material that can be used in the present invention include inorganic and organic materials. In view of productivity, strength, and the like, inorganic materials are preferable. In this case, the outer shell layer is formed of an inorganic material.

When the hollow fine particles are formed of an inorganic material, the hollow fine particle material is preferably at least one selected from the group consisting of metal oxides, metal nitrides, metal sulfides, and metal halides. If hollow fine particles are used as the above-mentioned material, fine particles can be obtained in which the outer shell has high strength and is not easily crushed by external pressure. More preferably, the material of the hollow fine particles is formed of a metal oxide or a metal halide, and particularly preferred is the use of porous silica (porous silica) as the hollow fine particles.
Porous silica is hollow shell silica fine particles, and the average particle diameter is preferably 10 to 200 nm, and more preferably 10 to 150 nm. If the average particle size of the porous silica is less than 10 nm, it is difficult to lower the refractive index of the porous silica, and if it exceeds 200 nm, light is diffusely reflected, and the surface roughness of the formed low refractive index layer is increased. There is a problem.

Porous silica has air having a low refractive index (refractive index = 1.0) inside the hollow, and therefore its refractive index is significantly lower than that of ordinary silica (refractive index = 1.46). The refractive index of the porous silica is determined by the volume ratio of the hollow part, but is usually preferably about 1.20 to 1.40.
The refractive index of porous silica: n (porous silica) is expressed by the following formula (1) from the refractive index of silica constituting the shell of hollow fine particles: n (silica) and the refractive index of air inside: n (air). ).
n (porous silica) = n (silica) × (silica volume fraction) (1)
Since n (silica) is about 1.47 and n (air) is as low as 1.0, the refractive index of such porous silica is very low.

In the present invention, the higher the content of porous silica in the low refractive index layer, the lower the refractive index layer can be formed, but the lower the binder component content, the lower the content. The film strength of the refractive index layer is lowered, and the scratch resistance and durability are lowered. However, the decrease in film strength due to the increase in the amount of porous silica can be compensated for by surface treatment of porous silica, and the film strength can also be supplemented by selecting the type of binder component to be blended. it can.
In the present invention, the porous silica content in the low refractive index layer is set to 20 to 50% by mass, particularly 25 to 50% by mass, by selecting the surface treatment of the porous silica, the resin component, and the like. It is preferable to increase the rate.

(Manufacturing method of multilayer structure)
The method for producing the multilayer structure is not particularly limited as long as the A layer and the B layer are laminated and bonded satisfactorily. For example, known methods such as co-extrusion, bonding, coating, bonding, and adhesion are known. This method can be adopted. Specifically, the method for producing the multilayer structure includes (1) using a resin composition for forming an A layer and a resin composition for forming a B layer, and having the A layer and the B layer by a multilayer coextrusion method. A method for producing a multilayer structure, and (2) using a resin composition for forming an A layer and a resin composition for forming a B layer, by laminating and stretching a plurality of laminates via an adhesive. Examples thereof include a method for producing a multilayer structure having an A layer and a B layer. Among these, from the viewpoint of high productivity and excellent interlayer adhesion, there is a method of molding by a multilayer coextrusion method using the resin composition for forming the A layer and the resin composition for forming the B layer of (1). preferable.

  In the multilayer coextrusion method, the resin composition for forming the A layer and the resin composition for forming the B layer are heated and melted, supplied from different extruders or pumps to the extrusion dies through the respective flow paths, and extruded. The multilayer structure is formed by laminating and bonding after being extruded into multiple layers from the die. As this extrusion die, for example, a multi-manifold die, a field block, a static mixer, or the like can be used.

  In the multilayer structure, the multilayer laminate obtained in this manner is irradiated with active energy rays as described above to promote the crosslinking reaction and further improve the interlayer adhesion between the A layer and the B layer. It is preferable to make it. Since the multilayer structure is thus irradiated with the active energy rays, the adhesion between the layers is enhanced, and as a result, the color development and the bending resistance of the multilayer film can be enhanced.

  The active energy rays are those having energy quanta among electromagnetic waves or charged particle beams, specifically, ultraviolet rays, γ rays, electron beams and the like. Among these active energy rays, an electron beam is preferable from the viewpoint of improving the interlayer adhesion. By using an electron beam as the active energy ray, the interlayer cross-linking reaction is further promoted, and the interlayer adhesion of the multilayer structure can be further improved.

  When irradiating an electron beam, various electron beam accelerators such as a cockroft Walton type, a bandegraft type, a resonant transformer type, an insulated core transformer type, a linear type, a dynamitron type, and a high frequency type are used as an electron beam source. It is preferable to irradiate within an irradiation dose range of 5 to 600 kGy with a normal acceleration voltage of 100 to 500 kV.

Moreover, when using an ultraviolet-ray as an active energy ray, it is good to irradiate what contains the ultraviolet-ray with a wavelength of 190-380 nm. The ultraviolet light source is not particularly limited, and for example, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a carbon arc lamp, or the like is used.
As described above, this multilayer structure is excellent in interlayer adhesion, and has high color developability, stretchability, thermoformability and durability.

  In the multilayer structure produced as described above, the peeling resistance between the A layer and the B layer is, after heating at 180 ° C. for 15 minutes, in accordance with JIS-K6854, at 23 ° C. under 50% RH atmosphere. In the measurement at a speed of 50 mm / min, it is preferably 25 N / 25 mm or more, more preferably 27 N / 25 mm or more, further preferably 30 N / 25 mm or more, and particularly preferably 50 N / 25 mm or more. Thus, the A layer and the B layer have very good interlayer adhesion.

  Moreover, this multilayer structure is not limited to the said embodiment. For example, other layers may be included in addition to the A layer and the B layer. Although the kind of resin composition which comprises this other layer is not specifically limited, A thing with high adhesiveness between A layer and / or B layer is preferable. The other layer has a molecular chain having a functional group that reacts with a hydroxyl group possessed by, for example, EVOH in the A layer, or a carbamate group or an isocyanate group in the molecular chain of, for example, TPU in the B layer. Those that are particularly preferred.

<Tire>
The tire of the present invention is configured by arranging the multilayer film described above on at least a part of the outer surface of the tire sidewall. Here, the said tire sidewall outer surface means the outer surface of the sidewall part in a tire. First, the structure of a tire is demonstrated using drawing.
FIG. 3 is a schematic partial cross-sectional view of a pneumatic tire showing an example of the tire of the present invention. In FIG. 3, a tire T includes an annular tread 1, a pair of sidewalls 2 extending in the tire radial direction from both ends of the tread 1, a bead portion 3 formed at an inner end of the sidewall 2, and an inside of the bead portion 3. An annular bead core 4 embedded in the carcass 5, a carcass 5 penetrating the tread 1 and the sidewall 2 and having both ends wound up around the bead core 4, an annular breaker 6 disposed outside the carcass 5 in the tread 1; An inner liner layer 7 provided on the inner surface of the tire and a multilayer film 8 provided on the outside (side wall outer surface) of the rubber layer forming the sidewall 2 are provided.

The multilayer film 8 provided on the outer side of the rubber layer of the sidewall 2 only needs to be disposed on at least a part of the outer surface of the sidewall 2, and is disposed on the entire outer surface of the sidewall 2 as shown in FIG. It may be arranged on a part of the outer surface.
The thickness of the multilayer film 8 is preferably in the range of 1 to 1000 μm, more preferably in the range of 10 to 200 μm, including the multilayer structure in the above-described preferable thickness range. When the thickness of the multilayer film 8 is less than 1 μm, the flexibility of the film is too high. For example, when the film is applied to the unvulcanized rubber of the sidewall 2, it tends to become wrinkles and it is difficult to form a smooth surface. On the other hand, when the thickness exceeds 1000 μm, the flexibility of the film is lowered, and the multilayer film 8 may be peeled off or damaged without being able to follow the deformation of the sidewall 2 during use.

  As a tire manufacturing method according to the present invention, a conventional method can be used except for the step of arranging the multilayer film 8 on the outer surface of the sidewall 2. For example, on a tire molding drum, members usually used for manufacturing a tire such as a carcass layer, a belt layer, and a tread layer made of unvulcanized rubber are sequentially laminated, and the drum is removed to obtain a green tire. Next, the desired tire can be manufactured by heat vulcanizing the green tire according to a conventional method.

  As a method of arranging the multilayer film 8 on the outer surface of the sidewall 2, for example, (1) a resin film to be the multilayer film 8 is stuck on the outer surface of the unvulcanized tire, and the unvulcanized tire is vulcanized in that state. The resin film is adhered to the outer surface of the sidewall 2 by molding. (2) A resin film to be the multilayer film 8 is attached to the outer surface of the tire after vulcanization using an adhesive, and the resin film is attached to the outer surface of the tire. There are two main methods of adhering to the outer surface of the sidewall 2.

  Regarding the method (1) above, in detail, a resin film cut into a predetermined shape is placed at a predetermined position on the outer surface of the side portion (ie, sidewall portion) in the tire (ie, green tire) before vulcanization. The resin film was placed on the outer surface of the sidewall portion as a multilayer film 2 by vulcanizing and molding the unvulcanized tire in a tire vulcanization mold while the resin film was attached. A pneumatic tire is manufactured.

  In this case, the arranged resin film can maintain the adhesiveness with the surface of the non-vulcanized tire having tackiness, and can prevent positional deviation of the resin film during vulcanization. The application of the resin film to the unvulcanized tire may be performed on the unvulcanized tire before setting the unvulcanized tire on the vulcanization mold, or A resin film may be set at a predetermined position, and the resin film may be affixed to an unvulcanized tire while closing in the vulcanization mold. Preferably, a resin film is stuck on an unvulcanized tire before being set in a vulcanization mold as in the former.

  The vulcanization molding of the unvulcanized tire itself can be performed according to a conventional method, and the structure of the vulcanization molding die is not particularly limited. Although it does not specifically limit about vulcanization temperature, Usually, it implements at 140-200 degreeC.

Next, regarding the method (2), in detail, the resin film cut into a predetermined shape is bonded to a predetermined position on the outer surface of the side portion (that is, the sidewall portion) in the vulcanized tire. Paste through the agent.
The material for the adhesive layer is not particularly limited as long as it can firmly bond the resin film to be the multilayer film 8 and the sidewall, but a diene polymer modified with a polar functional group (modified diene polymer) ) Is preferably included.
The polar functional group includes epoxy group, amino group, imino group, nitrile group, ammonium group, isocyanate group, imide group, amide group, hydrazo group, azo group, diazo group, hydroxyl group, carboxyl group, carbonyl group, oxy Examples thereof include a carbonyl group, a sulfide group, a disulfide group, a sulfonyl group, a sulfinyl group, a thiocarbonyl group, a nitrogen-containing heterocyclic group, an oxygen-containing heterocyclic group, an alkoxysilyl group, and a tin-containing group, and an epoxy group is particularly preferable.

  Examples of the modified diene polymer include modified natural rubber and / or modified synthetic rubber. Examples of the modified synthetic rubber include modified polyisoprene rubber (IR), modified polybutadiene rubber (BR), modified styrene-butadiene copolymer (SBR), and modified styrene-isoprene copolymer (SIR). These modified natural rubber and modified synthetic rubber are excellent in durability in a low temperature environment. As the modified diene polymer, epoxidized natural rubber (ENR) or epoxidized butadiene rubber (EBR) is also preferably used.

  The adhesive layer preferably contains two or more modified diene polymers having different modification rates. Thereby, the adhesiveness with a carcass can be improved with a modified diene polymer having a low degree of modification, and the adhesiveness with a thermoplastic resin film can be improved with a modified diene polymer with a high modification rate.

  The thickness of the adhesive layer is preferably 5 to 200 μm, more preferably 10 to 100 μm. When the thickness is 5 μm or more, the multilayer film and the sidewall can be firmly bonded, and the function of improving crack resistance in a low-temperature environment is satisfactorily exhibited. When it is 200 μm or less, weight reduction of the pneumatic tire is achieved.

In order to improve the adhesion of the sidewall 2 to the rubber layer, for example, a method of immersing the film in a resorcin formaldehyde latex solution (RFL treatment) on the resin film to be the multilayer film 8, and the film surface on the silane cup It is effective to perform a pretreatment for adhesion by a method of treating with a ring agent, a method of subjecting the film surface to a primary treatment by corona discharge, and then a secondary treatment with a silane coupling agent.
With the above configuration, the resin film can be securely adhered to the sidewall material by winding the surface of the resin film that becomes the multilayer film 8 having the adhesive layer in close contact with the sidewall material. Moreover, durability of the multilayer film 8 can be improved by performing these adhesion | attachment pre-processing.

  The tire 1 according to the embodiment of the present invention is filled with a gas such as air or nitrogen. The structure of the tire T shown in the figure is an example, and is not limited to the structure of FIG. For example, it may be a passenger car tire, a heavy duty tire, an off-the-road tire, a motorcycle tire, an aircraft tire, an agricultural tire, and the like.

Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.
First, a method for measuring and evaluating each characteristic according to the example will be described.

<Measurement method for each characteristic>
(1) Refractive index of thin layer (n)
About resin used for formation of each thin layer, it measured according to A method of JISK7142-2008.

(2) Young's modulus The resin used for forming each thin layer was pelletized, and this was formed into a single-layer film having a thickness of 20 μm using a twin-screw extruder (manufactured by Toyo Seiki Co., Ltd.) under the following extrusion conditions. .
・ Screw: 20 mmφ, full flight cylinder ・ Die temperature setting: C1 / C2 / C3 / die = 200/200/200/200 (° C.)
Next, a strip-shaped test piece having a width of 15 mm was prepared using the above film, and left in a temperature-controlled room under conditions of 23 ° C. and 50% RH for 1 week, and then an autograph (Shimadzu Corporation, AG-A500). Type) was used to measure an SS curve (stress-strain curve) at 23 ° C. and 50% RH under conditions of a chuck interval of 50 mm and a tensile speed of 50 mm / min, and Young's modulus in accordance with JIS K7161-1994. (Tensile modulus) was determined.

<Evaluation method>
In accordance with the production example described later, tires were produced in the embodiments, and the design and tire color change were evaluated by the following methods.
(1) Designability The tire side portion was visually observed, and the color development was evaluated according to the following criteria.
○: The side portion shows a transparent blue or green color, and the color changes depending on the viewing direction.
Δ: The side portion shows a transparent blue or green color, but the color does not change depending on the viewing direction.
X: The side portion is the rubber color (black) of the base, and the color does not change depending on the viewing direction.
Further, the reflection spectrum was evaluated using a microspectrophotometer (manufactured by Hitachi, model U-6000). The reflection spectrum was measured using a standard white plate as a reference under conditions of 0 ° incidence / 0 ° light reception, and the reflection peak wavelength and relative reflectance were measured.

(2) Evaluation of tire color change About a tire with a film obtained as described below attached to the side, the tire is mounted on a passenger car, and the inner pressure of the tire is 220 kPa and 160 kPa from the same point. Observations were made on the changes in color seen. In particular, the evaluation was given as ◯ when the size of the portion that changed to the rainbow color around the portion exhibiting the reflection color was easily changed due to the difference in internal pressure, and × when the size was not clear.

(3) Tire durability evaluation by drum running test The produced tire was pressed at a load of 6 kN on a drum having a rotation speed corresponding to a speed of 80 km / h at an air pressure of 140 kPa in an atmosphere of −20 ° C. and running for 10,000 km. did. The appearance of the side surface of the tire after running the drum was visually observed to evaluate the presence or absence of cracks in the multilayer film.

<Manufacture of multilayer film>
(Production Example 1) Production of multilayer film 1 Nylon (Ube Industries, Ltd., 5033B) pellets A1 (n: 1.530) and EPDM (Esplen 502, Sumitomo Chemical Co., Ltd.) pellets B1 (n: 1.480) 1 are alternately formed by the resin compositions constituting the pellets, and a multilayer structure of 33 layers of 16 layers A and 17 layers B in FIG. 1 is formed, and B layer as a support layer on the outermost surface. Was fed into a co-extruder in a molten state at 220 ° C. in a total of 35 layer feed blocks so as to be extruded at about 10 μm, and co-extruded and joined to form a multilayer laminate. The slit shape was designed so that the layer thicknesses of the adjacent A layer and B layer were substantially the same. The thus obtained laminate consisting of a total of 35 layers was rapidly cooled and solidified on a casting drum which was kept at a surface temperature of 35 ° C. and electrostatically applied. The cast film obtained by rapid cooling and solidification was pressure-bonded onto a release paper and wound up. In addition, the flow path shape and the total discharge amount were set so that the time from the melt of the pellets A1 and the pellets B1 to the rapid cooling and solidification on the casting drum was about 4 minutes.

  The cast film obtained as described above was subjected to cross-sectional observation with DIGITAL MICROSCOPE VHX-900 (manufactured by KEYENCE) and electron microscope VE-8800 (manufactured by KEYENCE). 0.08 μm, and the overall thickness was 23 μm. In addition, each thickness was made into the average value of the measured value in 9 points | pieces selected at random.

Next, this film was irradiated with an electron beam with an acceleration voltage of 200 kV and an irradiation dose of 200 kGy by an electron beam accelerator (manufactured by Nissin High Voltage, model name “Curetron EB200-100”) to obtain a multilayer film 1. .
The Young's moduli at 23 ° C. of pellets A1 and B1 measured separately as films were 4000 MPa and 10 MPa, respectively.

(Production Example 2) Production of Multilayer Film 2 In Production Example 1, the pellets used were thermoplastic urethane elastomer (Kuraray Co., Ltd., Kuramyron 3190) pellets A2 (n: 1.540) and EPDM pellets B2 (n: 1). 480), and a multilayer film 2 was obtained in the same manner as in Production Example 1 except that the melting temperature in the co-extruder was 200 ° C.
The average thickness of each of the A layer and the B layer in the multilayer film 2 was 0.08 μm, and the overall thickness was 23 μm. Further, the Young's moduli at 23 ° C. of pellets A2 and B2 measured separately as films were 15 MPa and 10 MPa, respectively.

(Production Example 3) Production of Multilayer Film 2 In Production Example 1, the pellets used were polycarbonate (Mitsubishi Engineering Plastics, Novalex H-3000) pellets A3 (n: 1.590) and polymethyl methacrylate. (PMMA, Sumitomo Chemical Co., Ltd., Sumipex MH) Pellets B3 (n: 1.487), and multilayer film 3 was obtained in the same manner as in Production Example 1 except that the melting temperature in the co-extruder was 260 ° C. .
The average thickness of each of the A layer and the B layer in the multilayer film 3 was 0.07 μm, and the overall thickness was 23 μm. Further, the Young's moduli at 23 ° C. of pellets A3 and B3 measured separately as films were 2490 MPa and 2900 MPa, respectively.

(Manufacture example 4) Manufacture of multilayer film 4 In manufacture example 1, it carried out similarly to manufacture example 1 except having performed coextrusion so that a four-layered laminate which made pellet A1 and pellet B1 into two layers may be formed. Thus, a multilayer film 4 was obtained.
The average thickness of each of the A layer and the B layer in the multilayer film 4 was 0.07 μm, and the overall thickness was 20 μm.

(Production Example 5) Production of multilayer film 5 and production of pellets Pellet A2: 30 parts by mass of ZrO ₂ (refractive index n = 2.2, manufactured by Toyo Ink Co., Ltd.) with respect to 100 parts by mass The mixture was melt-mixed at 190 ° C. using a machine to produce a high refractive index pellet A5. Further, with respect to 100 parts by mass of pellet B2, 50 parts by mass of porous silica fine particles (manufactured by Catalyst Kasei Kogyo Co., Ltd., refractive index n = 1.23, average particle size: 60 nm) were used using a twin screw extruder. The mixture was melted and mixed at 140 ° C. to produce a low refractive index pellet B5.
-Production of multilayer film In Production Example 1, the pellets used were the above pellet A5 (n: 1.650) and pellet B5 (n: 1.410), and the melting temperature in the co-extruder was 200 ° C, A multilayer film 5 was obtained in the same manner as in Production Example 1.
The average thickness of each of the A layer and the B layer in the multilayer film 5 was 0.08 μm, and the overall thickness was 22 μm. Further, the Young's moduli at 23 ° C. of pellets A5 and B5 measured separately as films were 18 MPa and 14 MPa, respectively.

(Manufacture example 6) Manufacture of multilayer film 6 In manufacture example 1, except coextruding so that the average thickness of each of A layer and B layer might be 0.55 micrometer, and the whole thickness may be 38 micrometers, Similarly, a multilayer film 6 was obtained.

(Production Example 7) Production of Multilayer Film 7 Production Example 1 is the same as Production Example 1 except that pellet B3 (n: 1.487) is used instead of pellet A1, and the melting temperature in the co-extruder is 260 ° C. Similarly, a multilayer film 7 was obtained.
The average thickness of each of the A layer and the B layer in the multilayer film 7 was 0.08 μm, and the overall thickness was 23 μm. Further, the Young's modulus at 23 ° C. of pellet B3 measured separately as a film was 2900 MPa.

<Example 1>
(Production of tire)
An unvulcanized green tire (195 / 65R15) was produced according to a conventional method. On the other hand, the multilayer film 1 is cut into a predetermined size, and the film is attached to the entire outer surface of the side portion of the green tire as shown in FIG. 3, and set in a steel tire molding mold in this state. Then, the tire 1 was obtained by heat vulcanization at 140 ° C. for 30 minutes.

The prototype tire 1 was used to evaluate the design properties and tire color change, and then the tire durability was evaluated.
These results are summarized in Table 1.

<Example 4, Reference Examples 1-3 , Comparative Examples 1-2>
In the production of the tire of Example 1, tires were produced in the same manner as in Example 1 except that the multilayer films 2 to 7 were used instead of the multilayer film 1, and the same evaluation was performed on these.
The results are summarized in Table 1.

As shown in the results of Table 1, the tire of Example 1 is superior in durability against distortion due to running, is superior in design to the tire of the comparative example, and is daily management of changes in tire internal pressure and the like. It turned out that it is excellent also in property.

DESCRIPTION OF SYMBOLS 1 Tread 2 Side wall 3 Bead part 4 Bead core 5 Carcass 6 Breaker 7 Inner liner layer 8 Multilayer film 10 Multilayer structure part 20 Protective layer part

Claims (8)

A tire in which a multilayer film is disposed on at least a part of an outer surface of a tire sidewall,
The multilayer film has an optical layer composed of five or more thin layers in which thin layers having a refractive index difference between adjacent layers of 0.01 or more are alternately stacked, and the average thickness of the thin layers is 0.01 μm or more. A tire having a thickness of 0.5 μm or less, wherein the optical layer includes a layer A made of a thermoplastic resin film and a layer B made of a resin composition containing an elastomer.   The tire according to claim 1, wherein a Young's modulus (JIS K7161-1994) at 23 ° C of at least one of the five or more thin layers is 0.1 MPa or more and 500 MPa or less. The tire according to claim 1 or 2 , wherein at least one of the five or more thin layers is made of a resin composition containing a thermoplastic elastomer. The thermoplastic elastomer is selected from among polystyrene-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, polydiene-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers and silicone-based thermoplastic elastomers. The tire according to claim 3, which is at least one selected. The tire according to any one of claims 1 to 4 , wherein a thin layer having a higher refractive index in an adjacent layer among the five or more thin layers includes at least one of metal fine particles and metal oxide fine particles. The tire according to any one of claims 1 to 5 , wherein a thin layer having a lower refractive index in an adjacent layer among the five or more thin layers includes hollow fine particles. The tire according to any one of claims 1 to 6 , wherein the total light transmittance in the multilayer film is 30% or more. It is a manufacturing method of the tire given in any 1 paragraph of Claims 1-7,
A method for manufacturing a tire, wherein the multilayer film is formed by a coextrusion process .

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