JP6673742B2 - Tire and manufacturing method thereof - Google Patents

Description

  The present invention relates to a tire and a method for manufacturing the tire.

In general, rubber used for tires and the like sometimes deteriorates under the influence of the outside air environment such as in the presence of ozone. As the rubber deteriorates, the rubber may be cracked.
To cope with such a problem, a technique of coating a surface of a tire or the like with polyurethane is known. Patent Document 1 discloses at least a part of a rubber outer surface based on a substantially unsaturated diene elastomer. A tire coated with a coating for protecting against ozone, wherein the coating comprises at least one layer in contact with air, selected from aliphatic polyethers or polyesters and polyethers or polyesters whose main chain is semi-aromatic. Disclosed are tires comprising a polyurethane prepared from the prepared polyol, wherein the bond between the elastomer and the polyurethane is formed by polar functional groups and the coating comprises a surfactant.

JP 2003-535762 A

  An object of the present invention is to provide a tire excellent in crack resistance, suppressed in discoloration over time, and excellent in productivity, and a method for producing the same.

  As a result of intensive studies, the present inventors have found that a tire obtained by laminating and vulcanizing a urethane resin foam on an unvulcanized rubber surface has an organotin compound catalyst in the urethane resin foam of pKa of 7 or more. It has been found that the above-mentioned problems can be solved by setting the content of the basic catalyst exceeding 8 to less than 8 and the content of the basic catalyst having a pKa of 8 to 9 in a specific range.

That is, the present invention relates to the following <1> to <9>.
<1> A tire in which a urethane resin-coated region including a rubber layer and a urethane resin layer covering the surface of the rubber layer to form a tire outer surface is formed in at least a part of the tire outer surface portion. The tire is a tire obtained by laminating a urethane resin foam on an unvulcanized rubber surface and vulcanizing the urethane resin foam. The urethane resin foam has an organotin compound catalyst and a pKa of 7. A basic catalyst having an excess of less than 8 and at least one catalyst selected from the group consisting of basic catalysts having a pKa of 8 or more and 9 or less, wherein the content of the organotin compound catalyst in the urethane resin foam is reduced. A (mass%), when the content of the basic catalyst having a pKa of more than 7 and less than 8 is B (mass%), and the content of the basic catalyst having a pKa of 8 or more and 9 or less is C (mass%), Satisfy the following formulas (1) to (3) A tire characterized by the following.
180 × A + B ≦ 3.3 (1)
10 × A + C ≦ 0.21 (2)
B + C> 0 (3)

<2> The tire according to <1>, wherein the rubber layer contains an aromatic anti-aging agent.
<3> The tire according to <2>, wherein the content of the aromatic antioxidant in the rubber layer is 0.5 to 10 parts by mass based on 100 parts by mass of the rubber component.
<4> The tire according to any one of <1> to <3>, wherein the content of the organotin compound catalyst in the urethane resin foam is 0 to 0.018 mass%.
<5> The tire according to any one of <1> to <4>, wherein the content of the basic catalyst having a pKa of more than 7 and less than 8 in the urethane resin foam is 0 to 3.3% by mass. .
<6> The tire according to any one of <1> to <5>, wherein the content of the basic catalyst having a pKa of 8 to 9 in the urethane resin foam is 0 to 0.21% by mass.
<7> The tire according to any one of <1> to <6>, wherein the urethane resin-coated region is formed in at least a part of a tire outer surface of a tread portion and / or a sidewall portion.
<8> The tire according to any one of <1> to <7>, wherein the urethane resin foam has an expansion ratio of 4 times or more.
<9> A method for producing a tire according to any one of <1> to <8>, wherein a urethane resin foam is laminated on an unvulcanized rubber surface and vulcanized. Manufacturing method.

  ADVANTAGE OF THE INVENTION According to this invention, the tire excellent in crack resistance, discoloration with time is suppressed, and also excellent in productivity, and its manufacturing method can be provided.

FIG. 1A is a photograph of an interface (tire outer surface portion) between a rubber layer and a urethane resin layer in a cross section in a tire width direction of a tire according to an embodiment of the present invention. FIG. 1B is a schematic diagram of FIG. 1A.

Hereinafter, the present invention will be described in detail based on its embodiments. In the following description, “A to B” indicating a numerical range indicates a numerical range including the end points A and B. When A <B, “A to B” and “A> In the case of B, it represents “A or less and B or more”.
Further, parts by mass and% by mass are synonymous with parts by weight and% by weight, respectively.

[tire]
In the tire of the present invention, a urethane resin-coated region composed of a rubber layer and a urethane resin layer that covers the surface of the rubber layer to form a tire outer surface is formed in at least a part of the tire outer surface portion. The tire is a tire obtained by laminating and vulcanizing a urethane resin foam on an unvulcanized rubber surface, and the urethane resin foam has an organotin compound catalyst, pKa Contains at least one catalyst selected from the group consisting of a basic catalyst having a pKa of more than 7 and less than 8 and a basic catalyst having a pKa of 8 or more and 9 or less, and wherein the organotin compound catalyst in the urethane resin foam contains The content is A (% by mass), the content of the basic catalyst having a pKa of more than 7 and less than 8 is B (% by mass), and the content of the basic catalyst having a pKa of 8 or more and 9 or less is C (% by mass). Then, the following equations (1) to (3) And satisfies.
180 × A + B ≦ 3.3 (1)
10 × A + C ≦ 0.21 (2)
B + C> 0 (3)

The present inventors have obtained by laminating a urethane resin foam on an unvulcanized rubber surface and vulcanizing, at least a partial region of the tire outer surface, a rubber layer, the surface of the rubber layer In a tire in which a urethane resin-coated region comprising a urethane resin layer that forms an outer surface of a tire by coating is formed, an organic tin compound catalyst or a basic catalyst (hereinafter, also referred to as an organic tin catalyst) contained in the urethane resin foam. ) Migrated to the rubber layer and promoted oxidation.
In particular, when the rubber layer contains an anti-aging agent, the anti-aging agent is consumed by the organotin catalyst or the like transferred from the urethane resin layer. The antioxidant thus consumed (oxidized antioxidant) migrates to the tire surface over time, and as a result, there is a problem in that the appearance of the tire is impaired.
The present inventors have conducted intensive studies and found that by setting the content of the organotin catalyst or the like to a specific range, discoloration over time is suppressed while maintaining the improvement in crack resistance due to the urethane resin layer. The tire was found to be excellent in productivity, and the present invention was completed.
Although the detailed mechanism of the above action is unknown, a part is presumed as follows. In other words, a tire having a urethane resin layer obtained by laminating a urethane resin foam on an unvulcanized rubber layer and vulcanizing the tire is one in which deterioration due to ozone is suppressed by the urethane resin layer and crack resistance is improved. it is conceivable that.
Further, the amounts of the organotin compound catalyst, the basic catalyst having a pKa of more than 7 and less than 8 and the amount of the basic catalyst having a pKa of 8 or more and 9 or less are within the ranges satisfying the above formulas (1) to (3). Thus, it is considered that the transfer of the organotin catalyst or the like from the urethane resin layer to the rubber layer was suppressed, and as a result, oxidation of the antioxidant and the like was suppressed, and discoloration over time was suppressed.
In addition, a tire manufacturing method in which a urethane resin foam layer is laminated on an unvulcanized rubber surface and vulcanized is superior in productivity to a method in which a urethane rubber layer is formed by spraying or the like.
Hereinafter, the present invention will be described in detail.

In the tire of the present embodiment, a urethane resin layer may be provided on the entire outer surface of the tire, or a urethane resin layer may be provided on a part of the outer surface of the tire. In the present invention, the urethane resin-coated region (region provided with the urethane resin layer) is preferably a tread portion and / or a sidewall portion.
The proportion occupied by the urethane resin-coated region on the outer surface of the tire of the present embodiment is preferably 1 to 100% with respect to the entire outer surface area (100%) of the tire. Further, for example, when a urethane resin-coated region is provided on the outer surface of the sidewall portion, it is preferably 10 to 100% with respect to the entire outer surface area (100%) of the sidewall portion.
In addition, "the whole tire outer surface" means the outer surface of the tire pinched between two bead heel parts. Further, the “entire outer surface of the sidewall portion” refers to an outer surface from the tread contact edge to the bead heel portion.
Here, the `` tread grounding end '' refers to a flat plate that is mounted on the applicable rim and placed perpendicular to the flat plate while the tire filled with the specified internal pressure is stationary and the load corresponding to the maximum load capacity is applied. At both ends in the tire width direction at the contact surface.
The “applicable rim” is an industrial standard effective in a region where a tire is produced or used. For example, in Japan, JATMA (Japan Automobile Tire Association) JATMA YEAR BOOK, and in Europe, ETRTO (The European). Standard rims of applicable sizes (STANDARD RMS of ETRTO REAR MEASURED) are described in STANDARDS MANUAL of TIRE and RIM Technical Organization, and standard rims of applicable sizes described in YEAR BOOK of TIRE and Rim Association (Inc.) of the United States. In BOOK, it refers to Design Rim). In addition, "prescribed internal pressure" refers to the air pressure corresponding to the maximum load capacity in the applicable size and ply rating described in the above JATMA YEAR BOOK, etc., and "maximum load capacity" refers to the tire specified in the above standard. It refers to the maximum mass allowed to be loaded.

  The tire includes, for example, a tread portion, a pair of sidewall portions extending inward in the tire radial direction from both side portions of the tread portion, and a bead portion extending inward in the tire radial direction from each sidewall portion. A tire having a general structure including a carcass extending toroidally between a pair of bead portions and a belt disposed radially outward of the carcass.

<Rubber layer>
As the rubber forming the rubber layer (for example, a tread rubber forming a rubber layer of a tread portion or a side rubber forming a rubber layer of a side wall portion), for example, a rubber containing a rubber component, a compounding agent and the like (rubber component, compounding agent) Rubber obtained by vulcanizing (crosslinking) a rubber composition containing the same.
The rubber component can be appropriately selected depending on the purpose. The rubber component is preferably at least one selected from the group consisting of natural rubber and synthetic rubber. As the rubber component, natural rubber may be used alone, synthetic rubber may be used alone, or natural rubber and synthetic rubber may be used in combination.
The synthetic rubber is not particularly limited, but a synthetic diene rubber is preferably exemplified. Examples of the synthetic diene rubber include polybutadiene rubber (BR), polyisoprene rubber (IR), styrene-butadiene copolymer rubber (SBR), styrene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, and ethylene. -Propylene copolymer rubber, ethylene-propylene-diene terpolymer rubber, chloroprene rubber, butyl rubber (isobutylene-isoprene copolymer rubber), halogenated butyl rubber, acrylonitrile-butadiene rubber, and the like. These synthetic rubbers may be used alone or in combination of two or more.

  Examples of the compounding agents include vulcanization accelerators (guadinine-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, thiuram-based, dithiocarbamate-based, and xanthate-based vulcanization accelerators). Accelerators, etc.), vulcanizing agents (sulfur, etc.), anti-aging agents (aromatic anti-aging agents, etc.), waxes (synthetic waxes, natural waxes, etc.), oils (aroma oils, etc.), fillers (silica, carbon black) , Calcium carbonate, etc.), silane coupling agents, organic acid compounds (stearic acid, etc.), zinc oxide, reinforcing agents, softeners, fillers (silica, carbon black, etc.), coloring agents, flame retardants, lubricants, plasticizers, Processing aids, thermoplastic resins, thermosetting resins, and the like. The above-mentioned compounding agents may be used alone or in combination of two or more.

(Aromatic anti-aging agent)
Among these, in the present invention, the rubber layer preferably contains an antioxidant as a compounding agent, and more preferably contains an aromatic antioxidant.
Examples of the aromatic antiaging agent include octylated diphenylamine, 4,4′-bis (α, α-dimethylbenzyl) diphenylamine, p- (p-toluenesulfonylamide) diphenylamine, and N, N′-di-2-naphthyl. Aromatic secondary amine aging such as -p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N-phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine Monophenol-based antioxidants such as 2,6-di-tert-butyl-4-methylphenol and mono (or di- or tri) (α-methylbenzyl) phenol, and 2,2′-methylenebis (4 -Ethyl-6-tert-butylphenol), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), 4,4′-butyl Bisphenol-based antioxidants, such as tyridenbis (3-methyl-6-tert-butylphenol), butylated reaction products of p-cresol and dicyclopentadiene (for example, Nocrack PBK, manufactured by Ouchi Shinko Chemical Co., Ltd.), Polyphenol-based antioxidants such as 2,5-di-tert-butylhydroquinone, 2,5-di-tert-amylhydroquinone, 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, zinc salt of 2-mercaptobenzimidazole, etc. And benzimidazole antioxidants.
Among these, an aromatic secondary amine-based antioxidant is preferable, and N-phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine is more preferable.
The content of the antioxidant is preferably at least 0.1 part by mass, more preferably at least 0.5 part by mass, and preferably at least 1.5 parts by mass with respect to 100 parts by mass of the rubber component. More preferably, it is even more preferably 2.5 parts by mass or more, and even more preferably 3 parts by mass or more. Further, it is preferably at most 10 parts by mass, more preferably at most 8 parts by mass, further preferably at most 5 parts by mass. When the content of the antioxidant is in the above range, the aging of the rubber layer is prevented, the crack resistance is excellent, and the problem of discoloration is further suppressed.

The elastic modulus (sometimes referred to as “rubber elastic modulus” in the present specification) of the rubber layer (for example, tread rubber or side rubber) is, for example, from the viewpoint of further increasing the bonding strength with the urethane resin layer. The pressure is preferably from 1 to 100 MPa, more preferably from 3 to 100 MPa.
The rubber elastic modulus refers to a rebound resilience determined by a Lupke rebound resilience test in accordance with JIS K6255-1996.

<Urethane resin layer>
The urethane resin layer contains at least a urethane resin, and may further contain another resin (for example, an acrylic resin, an epoxy resin, a phenol resin, or the like). The urethane resin layer is formed by laminating a urethane resin foam on an unvulcanized rubber surface and vulcanizing it. Therefore, the urethane resin layer is a layer formed by overheating and compressing the urethane resin foam when vulcanizing the unvulcanized rubber.
As the urethane resin, for example, a two-part curable urethane resin prepared from a polyol and a polyisocyanate is preferable.
Examples of the polyol component include compounds such as ethylene glycol, propylene glycol, 1,4-butanediol, glycerol, trimethylolpropane, 1,2,6-hexanetriol, erythritol, and sorbitol as low molecular polyols.
Polyoxyethylene glycol, polyoxyethylene glyceryl ether, polyoxyethylene trimethylolpropane ether, polyoxyethylene sorbitol ether, polyoxypropylene bisphenol A ether, polyoxypropylene glycol, polyoxypropylene Glyceryl ether, polyoxypropylene trimethylolpropane ether, polyoxypropylene sorbitol ether, polyoxypropylene bisphenol A ether, polyoxyethylene-polyoxypropylene glycol, polyoxyethylene-polyoxypropylene glyceryl ether, polyoxyethylene-polyoxypropylene Trimethylolpropane ether, polyoxyethyl Down - polyoxypropylene sorbitol ethers, polyoxyethylene - consisting compounds such polyoxypropylene bisphenol A ether, polyoxyalkylene - polyol can be exemplified. Examples of polyester-based polyols include polyhydric alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, neopentyl glycol, and trimethylolpropane, and phthalic acid, maleic acid, malonic acid, succinic acid, and adipine. Acid, a condensate with a polycarboxylic acid such as terephthalic acid, which has a hydroxyl group at a terminal, or a ring-opening polymerization of a polyhydric alcohol with a cyclic lactone such as γ-butyrolactone, δ-valerolactone, ε-caprolactone. A product which also has a hydroxyl group at a terminal can be mentioned. Specific examples include polyethylene adipate polyol, polybutylene adipate polyol, polyethylene / butylene adipate polyol, and polyethylene terephthalate polyol.

  The polyisocyanate may be any organic isocyanate having two or more isocyanate groups in one molecule, such as 4,4′-diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), dicyclohexyl methane diisocyanate, xylene diisocyanate, It is preferable to use at least one selected from methylene diisocyanate, isophorone diisocyanate, o-toluidine diisocyanate, naphthylene diisocyanate, xylylene diisocyanate, lysine diisocyanate and polymethylene polyphenylene polyisocyanate, and 4,4′-diphenylmethane diisocyanate, Isocyanate, xylene diisocyanate, hexamethylene diisocyanate, o-toluidine Diisocyanate, naphthylene diisocyanate, xylylene diisocyanate, such as polymethylene polyphenylene polyisocyanate, aromatic polyisocyanate is preferred. It is particularly preferable to use 4,4'-diphenylmethane diisocyanate: MDI and / or tolylene diisocyanate: TDI. When both are used in combination, the ratio of the parts by mass of TDI / parts by mass of MDI (TDI / MDI) can be used in any range, but is preferably in the range of 0.05 to 20, more preferably 0.2 to 5 More preferably, it is within the range.

In the above method for synthesizing a polyurethane from a polyol and a polyisocyanate, as the catalyst, any catalyst used in the production of ordinary urethane foam can be used. Examples thereof include tin-based catalysts such as dibutyltin dilaurate and stannas octoate, and tertiary amines such as triethylamine and tetramethylhexanemethylenediamine. In the present invention, an organic tin compound catalyst is used as a catalyst used in the synthesis of polyurethane. And at least one selected from the group consisting of a basic catalyst having a pKa of more than 7 and less than 8 and a basic catalyst having a pKa of 8 or more and 9 or less. Thereby, the urethane resin layer contains at least one selected from the group consisting of an organotin compound catalyst, a basic catalyst having a pKa of more than 7 and less than 8, and a basic catalyst having a pKa of 8 or more and 9 or less. In the present invention, pKa means pKa in water.
Examples of the organotin compound catalyst include dibutyltin dichloride, dibutyltin oxide, dibutyltin dibromide, dibutyltin dimaleate, dibutyltin dilaurate (DBTDL), dibutyltin diacetate, dibutyltin sulfide, tributyltin sulfide, tributyltin oxide, and tributyltin oxide. Examples thereof include acetate, triethyltin ethoxide, tributyltin ethoxide, dioctyltin oxide, tributyltin chloride, tributyltin trichloroacetate, and tin 2-ethylhexanoate. Among these, tin 2-ethylhexanoate is preferred from the viewpoint that a sufficient catalytic ability can be obtained with a small amount.
The content of the organotin compound catalyst in the urethane resin foam is preferably 0 to 0.018% by mass, more preferably 0 to 0.01% by mass, and 0 to 0.008% by mass. It is even more preferred.

Examples of the basic catalyst having a pKa of more than 7 and less than 8 include N-methylmorpholine (pKa = 7.67), N-ethylmorpholine (pKa = 7.67), ethylenediamine (pKa = 7.12), and triamine. Ethanolamine (pKa = 7.76), N-methylenediamine (pKa = 7.42) and the like are exemplified. When the basic catalyst has two or more pKa, the first pKa is more than 7 and less than 8.
Among these, N-methylmorpholine, ethylenediamine, and triethanolamine are preferred from the viewpoint of obtaining a high catalytic ability with a small amount.
The content of the basic catalyst having a pKa of more than 7 and less than 8 in the urethane resin foam is preferably 0 to 3.3% by mass, and more preferably 1.5 to 3% by mass.
In the present invention, pKa is determined by a known method {for example, Can. J. Chem. 65, 626 (1987)} and means pKa in water.

Examples of the basic catalyst having a pKa of 8 or more and 9 or less include triethylenediamine (pKa = 8.8), diethanolamine (pKa = 8.87), and tris [2- (dimethylamino) ethyl] amine (pKa = 8.8). 17) is exemplified. When the basic catalyst has two or more pKas, the first pKa is 8 or more and 9 or less.
Among these, triethylenediamine and diethanolamine are preferred from the viewpoint of obtaining a high catalytic ability with a small amount.
The content of the basic catalyst having a pKa of 8 or more and 9 or less in the urethane resin foam is preferably 0 to 0.21% by mass, and more preferably 0 to 0.2%.

In the present invention, the content of the organotin compound catalyst in the urethane resin foam is A (% by mass), the content of the basic catalyst having a pKa of more than 7 and less than 8 is B (% by mass), and the pKa is 8 to 9%. When the content of the following basic catalyst is C (mass%), the following formulas (1) to (3) are satisfied.
180 × A + B ≦ 3.3 (1)
10 × A + C ≦ 0.21 (2)
B + C> 0 (3)
In the present invention, by satisfying the above expressions (1) to (3), discoloration of the tire is suppressed. That is, the discoloration of the tire is prevented by suppressing the content of the organotin catalyst or the like to a small amount.
Formulas (1) and (2) mean that the catalyst having a higher pKa contributes more to the discoloration of the tire, and the formula (3) indicates that the pKa is more than 7 and less than 8 And at least one basic catalyst selected from the group consisting of basic catalysts having a pKa of 8 or more and 9 or less.

Here, (180 × A + B) in the formula (1) is 3.3 or less, preferably 3.0 or less, and more preferably 2.5 or less. The lower limit is not particularly limited, but is preferably 1.0 or more, more preferably 1.5 or more, from the viewpoint of urethane synthesis.
(10 × A + C) in the expression (2) is 0.21 or less, and preferably 0.20 or less. The lower limit is not particularly limited, but is preferably 0.01 or more from the viewpoint of urethane synthesis.

  (B + C) in the formula (3) is more than 0, preferably 0.05 or more, more preferably 0.1 or more, and further preferably 0.15 or more. Further, it is preferably at most 3.5, more preferably at most 3.0, even more preferably at most 2.5.

  When producing a urethane resin foam, the content in the urethane resin foam can be approximated by the charged amount of the organic tin compound and the basic catalyst with respect to the polyol compound and the polyisocyanate compound as the raw materials. However, it is assumed that the hydroxyl group in the polyol compound and the isocyanate group in the polyisocyanate compound are approximately equivalent.

  The proportion of the urethane resin in the urethane resin layer is, for example, 10 to 100% by mass with respect to 100% by mass of the urethane resin layer from the viewpoint that the strength of adhesion to the rubber layer is further increased and the rubber layer is more easily followed. % By mass is preferred. It is preferable that the resin component in the urethane resin layer is only a urethane resin (does not include any other resin) from the viewpoint of balance of mechanical properties with the rubber layer.

The average thickness of the urethane resin layer is, for example, preferably 15 to 400 mm, more preferably, from the viewpoint of further increasing the bonding strength between the rubber layer and the urethane resin layer and further improving the crack resistance of the tire outer surface. Is 30 to 300 mm.
Above all, from the viewpoint of further increasing the bonding strength between the rubber layer and the urethane resin layer, when the rubber elastic modulus / the urethane resin elastic modulus <１ ／, it is difficult for the urethane resin layer to follow the rubber layer surface. From the viewpoint, the average thickness of the urethane resin layer is preferably 15 to 40 mm. When the rubber elastic modulus / the urethane resin elastic modulus ≧ 1/3, the urethane resin layer easily follows the surface of the rubber layer, and is hardly peeled off even if the urethane resin layer is thick, and the crack resistance is further improved. From the viewpoint of being excellent, the average thickness of the urethane resin layer is preferably larger than 40 mm.
The average thickness of the urethane resin layer was reduced from the point on the interface between the two points A and B in FIG. 1 described later in the cross section in the tire width direction to the tire outer surface (urethane resin coating region surface). The length of the perpendicular line to the feet (C and D in FIG. 1B) is defined as the thickness of the urethane resin layer at that point, and the average value of the thickness measured at all points between the two points A and B is calculated. Say.

If the two points A and B are selected from the interface between the rubber layer 2 and the urethane resin layer 1, the line on the interface connecting the two points A and B is a portion where the urethane resin layer is not provided (outside the tire). (A part to be a surface).
The portion where the urethane resin layer is not provided between the two points A and B is, for example, a perpendicular foot C (C in FIG. 1B) drawn from the point A to the surface of the urethane resin coating region 3 and a point The length (100%) of the line α on the outer surface of the tire, which is a connection between B and a perpendicular foot D (D in FIG. 1B) drawn on the surface of the urethane resin-coated region 3, The length of the portion where α is not provided with the urethane resin layer 1 (the portion where the line α is on the outer surface of the tire) is preferably 40% or less, more preferably 20% or less. In particular, it is preferable that there is no portion on the line α where the urethane resin layer 1 is not provided.
In addition, the length of the portion where the urethane resin layer 1 is not provided on the line α is preferably, for example, less than 200 μm from the viewpoint of the adhesive strength between the rubber layer 2 and the urethane resin layer 1.

If there is no portion where the urethane resin layer 1 is not provided on the shortest line on the tire outer surface connecting the two points C and D, the minimum thickness d of the urethane resin layer between the two points A and B is as follows: From the viewpoint of excellent ozone resistance, for example, the thickness is preferably 1 to 400 mm, and more preferably 30 to 400 mm.
Note that the minimum thickness d of the urethane resin layer between the two points C and D is the thickness of the urethane resin layer when calculating the average thickness of the urethane resin layer in the cross section in the tire width direction including the two points A and B. This is the minimum value (see FIG. 1B).

In the tire of the present invention, at least a part of the outer surface portion of the tire, a rubber layer, a urethane resin layer covering the surface of the rubber layer and forming a tire outer surface, a urethane resin coating region formed of In the cross section in the tire width direction, two points A and B on the interface between the rubber layer and the resin layer in the cross section in the tire width direction, and the length of the line segment AB is X, AB Assuming that the length of the interface between them is Y, there are two points A and B such that X ≧ 1 mm and Y / X ≧ 1.1 (however, the line segment AB passes outside the tire). (Excluding two points).
FIG. 1 shows an embodiment of a tire preferred in the present invention. In FIG. 1, in at least a part of the tire outer surface portion, a resin coating region 3 including a rubber layer 2 and a resin layer 1 that covers the surface of the rubber layer 2 and forms a tire outer surface is formed. ing.

The length X of the line segment AB is more preferably 1 to 5 mm, and still more preferably 1 mm.
The above Y / X is more preferably 1.2 or more, and still more preferably 1.3 or more. Further, it is preferably 4 or less.
When the ratio Y / X is 1.1 or more, the urethane resin layer follows the uneven shape of the surface of the rubber layer, and the rubber layer and the resin layer are complicatedly entangled at the interface between the rubber layer and the urethane resin layer. This is preferable because an anchor effect is obtained and the bonding strength of the urethane resin layer is significantly improved.
In addition, referring to FIG. 1, the length Y of the interface between the two points A and B is a line connecting the two points A and B along the interface between the rubber layer 2 and the urethane resin layer 1. (Extended length on the interface between the two points A and B) (see FIG. 1B). When no bubbles or the like exist between the rubber layer 2 and the urethane resin layer 1, the interface between the rubber layer 2 and the urethane resin layer 1 is the surface of the rubber layer (see FIG. 1B).

In the present invention, the maximum height roughness Ry of the interface between the rubber layer 2 and the urethane resin layer 1 between the two points A and B is such that the resin enters the rubber layer in a complicated manner, so that the urethane resin From the viewpoint that the rubber layer and the rubber layer are complicatedly entangled with each other and the bonding strength between the rubber layer and the urethane resin layer is improved, for example, the thickness is 5 to 400 μm.
Note that the maximum height roughness Ry refers to a value measured in accordance with the provisions of JIS B 0601: 2001.

(Urethane resin foam)
The tire of the present invention is a tire obtained by laminating a urethane resin foam on an unvulcanized rubber surface and vulcanizing, and the urethane resin layer is formed by overheating and compressing the urethane resin foam. Is done.
The urethane resin foam can be produced, for example, by foaming a composition containing the urethane resin and a foaming agent (foaming gas). The composition for forming the urethane resin foam may further include another resin (for example, the above-described other resin), a surfactant, a solvent, and the like.
Examples of the foaming agent (foaming gas) include water, hydrocarbon compounds (propane, butane, pentane, and the like), carbon dioxide gas, nitrogen gas, air, and the like.
The method for producing the urethane resin foam is not particularly limited, and a known method such as a one-shot method or a prepolymer method can be used. In the one-shot method, a polyol and an isocyanate are mixed and reacted (foamed) in the presence of a foam stabilizer, a catalyst, and a foaming agent. In the prepolymer method, a polyol and an isocyanate are preliminarily reacted to obtain a urethane prepolymer, which is then mixed with a foam stabilizer, a catalyst, a foaming agent, and, if necessary, further reacted (foamed) with a polyol. It is.
There is no particular limitation on the method of foaming and molding a polyurethane foam, and examples thereof include a slab foaming method, a molding method, and an on-site spray molding method. Among them, the slab foaming method is preferable. In the slab foaming method, for example, a polyurethane foam stock solution mixed and stirred by a one-shot method is discharged onto a belt conveyor, and the polyurethane foam stock solution spontaneously foams at room temperature and atmospheric pressure while the belt conveyor moves. It is a curing method. Usually, after that, it is cured in a drying oven and cut into a predetermined shape.

  The cell structure of the urethane resin foam is, for example, semi-continuous and semi-continuous from the viewpoint that bubbles are less likely to enter between the rubber layer and the urethane resin layer, and the bonding strength between the rubber layer and the urethane resin layer is further improved. A closed cell structure (a cell structure in which a closed cell structure and an open cell structure are mixed) or an open cell structure is preferable.

The expansion ratio of the urethane resin foam is, for example, preferably 50 times or less, more preferably 20 times or less, from the viewpoint of further improving the bonding strength between the rubber layer and the urethane resin layer. In addition, it is preferably at least 4 times, more preferably at least 8 times, from the viewpoint that air bubbles hardly enter between the rubber layer and the urethane resin layer, and the bonding strength between the rubber layer and the urethane resin layer is further improved.
The expansion ratio refers to “density before foaming / density after foaming”. That is, it refers to "the density of the composition obtained by removing the foaming agent from the composition forming the urethane resin foam / the density of the urethane resin foam". In addition, the volume of a foam refers to the volume measured based on JISK7222: 2005.

Further, the density of the composition excluding the foaming agent from the composition forming the urethane resin foam is not particularly limited, but is preferably 0.4 to 37.5 kg / m ³ , and more preferably 1.0 to 12 kg / m ³ . it is a 5kg / ^{m 3.}
The density of the urethane resin foam is not particularly limited, from the viewpoint of improving the strength of adhesion between the tire surface and the urethane layer is preferably 20~150kg / ^{m 3,} more preferably from 20 and 100 kg / ^{m 3.}
In addition, the said density says the value measured based on JISK7222: 2005.

<Tire manufacturing method>
The tire of the present invention is obtained by laminating a urethane resin foam on an unvulcanized rubber surface and vulcanizing it. In the tire of the present invention obtained as described above, the urethane resin easily enters the rubber layer surface at the time of vulcanization, the urethane resin and the rubber of the tire are intertwined in a complicated manner, and a high anchoring effect is obtained. It is preferable from the viewpoint of improving the bonding strength between the resin and the urethane resin layer.
In addition, when the urethane resin layer is provided on the tire outer surface after molding and vulcanization, the tire outer surface becomes substantially flat, the rubber layer and the urethane resin layer do not become complicatedly entangled, and the bonding strength may be insufficient. is there.

Examples of the vulcanization method include a method in which the urethane resin foam and the unvulcanized rubber (unvulcanized tire) are placed in contact with the inner surface of a mold and vulcanized and molded.
The vulcanization temperature is, for example, 140 to 200 ° C. The vulcanization time is, for example, 5 to 60 minutes.

  The tire of the present embodiment can be used, for example, as a tire for automobiles, heavy-duty vehicles (construction / mine vehicles, trucks / buses, etc.), motorcycles, bicycles, and the like.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

The components used in the examples and comparative examples are as follows.
6PPD: N-phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine (aromatic secondary amine-based antioxidant), manufactured by Ouchi Shinko Chemical Co., Ltd., trade name: Nocrack 6C
・ N-methylmorpholine: pKa = 7.4, manufactured by Nippon Emulsifier Co., Ltd. ・ Triethylenediamine: pKa = 8.8, manufactured by Tosoh Corporation, trade name “TEDA L33” (mixture of dipropylene glycol and triethylenediamine)
-Organotin compound catalyst: manufactured by Nippon Chemical Industry Co., Ltd., trade name "Nikka Octix Tin" (stannic 2-ethylhexylate (active ingredient amount 28% by weight))

Examples 1 to 8 and Comparative Examples 1 to 8
[Preparation of unvulcanized rubber composition]
The components shown in Table 1 below were mixed to prepare an unvulcanized rubber composition. The amount of the antioxidant added was appropriately changed as shown in Table 2 below.

Each component in Table 1 is as follows.
* 1 JSR “# 1500”
* 2 Tokai Carbon Co., Ltd., Trademark: Seast KH (N339)
* 3 Nippon Silica Co., Ltd., trademark: Nipsil AQ
* 4 Degussa Co., Ltd., trademark Si69, bis (3-triethoxysilylpropyl) tetrasulfide * 5 N-phenyl-N '-(1,3-dimethylbutyl) -p-phenylenediamine (Ouchi Shinko Chemical Industry Co., Ltd.) Nocrack 6C)
* 6 Diphenylguanidine (Ouchi Shinko Chemical Co., Ltd., Noxeller D)
* 7 Dibenzothiazyl disulfide (Noxeller DM-P, manufactured by Ouchi Shinko Chemical Co., Ltd.)
* 8 Nt-butyl-2-benzothiazylsulfenamide (manufactured by Sanshin Chemical Industry Co., Ltd., Suncellor NS-G)

[Preparation of urethane resin foam-1]
100 g of a polyol (manufactured by Nippon Polyurethane Co., Ltd., trade name "N2200-64") is weighed and placed in a predetermined container, and 2.0 g of water is added thereto. Momentive Co., Ltd., trade name "L-530": 0.5 g was weighed, mixed by stirring with a stirrer, and mixed by stirring to prepare a polyol component. Next, a predetermined amount of isocyanate (TDI: tolylene diisocyanate, an amount of TDI in which the hydroxyl group and the isocyanate group of the polyol are equivalent) is added to a container containing a mixture of the above polyol components, stirred, and then foamed at room temperature. And cured to obtain a block-like polyurethane foam.

[Preparation of urethane resin foam-2 to 15]
Urethane resin foams 2 to 15 were prepared in the same manner as urethane resin foam-1, except that the amount of catalyst used was changed as shown in Table 2.
In Table 2, the contents of the organotin compound catalyst, N-methylmorpholine, and triethylenediamine are addition amounts as solid contents.
The expansion ratios of the urethane resin foams 1 to 15 are as shown in Table 2.

[Production of tires]
A urethane resin foam of about 3 mm (adjusted to a thickness of about 100 μm after thinning (vulcanization)) was laminated on an unvulcanized tire, and vulcanized at 170 ° C. for 7 minutes to produce a tire.
In addition, about the tire obtained in the Example, it cut | disconnected in the tire width direction and the cross section in the tire width direction was image | photographed. In the obtained image, two points a and b on the interface between the rubber layer and the urethane resin layer in the urethane resin coating region are determined so that the length of the line segment ab is 1 mm, and the distance between the two points a and b is determined. The length y (mm) of the interface was measured. Then, the ratio (Y / X) between the length X of the line segment ab and the length Y of the interface between the abs was calculated by the following equation.
Y / X = Interface length between abs / Length between abs = y / 1
As a result, in Examples, Y / X was 1.1 or more.

[Evaluation]
The following evaluation was performed about the obtained tire.
<Rubber elastic modulus>
The rubber elastic modulus was determined by cutting out a rectangular parallelepiped test piece having a width of 5 mm, a length of 40 mm, and a depth of 2 mm from the tread portion of the tire, and using a spectrometer (Toyo Seiki Co., Ltd.), a distance between chucks of 10 mm and an initial strain of 150 μm. The storage elastic modulus (MPa) was measured under the conditions of a dynamic strain of 1%, a frequency of 52 Hz, and room temperature (25 ° C.).

<Membrane productivity>
The productivity of the membrane was evaluated according to the following evaluation criteria.
○: good foaming △: foaming difficult ×: foaming impossible

<Crack resistance>
The urethane resin-coated tires and tires obtained in Examples and Comparative Examples were cut out, and the temperature was 40 ° C. using an ozone weather meter (trade name “OMS-H”, manufactured by Suga Test Instruments Co., Ltd.) according to JIS K6259: 2004. Exposure was performed under conditions of a tensile strain of 30% and an ozone concentration of 50 pphm. After a lapse of 3 days, the urethane resin-coated region on the outer surface of the tire (the outer surface of the tire in Comparative Example 7) was observed, and the crack resistance was evaluated according to the following evaluation criteria in accordance with JIS K6259: 2004.
(Evaluation criteria)
：: No cracks ：: Degree of initial nucleus found ×: Cracks have developed

<Color difference index>
Based on JIS Z8701: 1999, a and b were measured with a color difference meter, and the total value of a and b was indexed with each of a and b in Comparative Example 7 being 100. The measurement was performed at the center of the sample after evaluating the crack resistance.

In Examples 1 to 8 satisfying the formulas (1) to (3), tires having excellent film productivity, excellent crack resistance, and suppressed discoloration over time were obtained.
On the other hand, in Comparative Example 1, which did not satisfy the formula (3), no subsequent evaluation was performed because a urethane resin foam could not be obtained. Further, Comparative Example 8, which did not contain both the organotin catalyst and the basic catalyst, was not evaluated since a urethane resin foam could not be obtained.
In Comparative Examples 2 to 7, which did not satisfy the formula (1) or the formula (2), although a urethane resin foam could be formed, it was found that discoloration with time was more likely to occur than in the examples.
In Comparative Example 7 in which the surface protective film was not formed, crack resistance was poor.

  ADVANTAGE OF THE INVENTION According to this invention, the tire excellent in crack resistance, discoloration with time is suppressed, and also excellent in productivity, and its manufacturing method can be provided.

Claims (9)

A tire in which a urethane resin-coated region composed of a rubber layer and a urethane resin layer covering the surface of the rubber layer to form a tire outer surface is formed on at least a part of the tire outer surface portion,
The tire is a tire obtained by laminating a urethane resin foam on an unvulcanized rubber surface and vulcanizing the tire,
The urethane resin foam contains at least one catalyst selected from the group consisting of an organotin compound catalyst, a basic catalyst having a pKa of more than 7 and less than 8, and a basic catalyst having a pKa of 8 or more and 9 or less. ,
The content of the organotin compound catalyst in the urethane resin foam is A (% by mass), the content of the basic catalyst having a pKa of more than 7 and less than 8 is B (% by mass), and a base having a pKa of 8 or more and 9 or less. A tire characterized by satisfying the following formulas (1) to (3) when the content of the reactive catalyst is C (mass%).
180 × A + B ≦ 3.3 (1)
10 × A + C ≦ 0.21 (2)
B + C> 0 (3)   The tire according to claim 1, wherein the rubber layer contains an aromatic antioxidant. The tire according to claim 2, wherein the content of the aromatic antioxidant in the rubber layer is 0.5 to 10 parts by mass with respect to 100 parts by mass of the rubber component.   The tire according to any one of claims 1 to 3, wherein the content of the organotin compound catalyst in the urethane resin foam is 0 to 0.018% by mass.   The tire according to any one of claims 1 to 4, wherein the content of the basic catalyst having a pKa of more than 7 and less than 8 in the urethane resin foam is 0 to 3.3% by mass.   The tire according to any one of claims 1 to 5, wherein the content of the basic catalyst having a pKa of 8 to 9 in the urethane resin foam is 0 to 0.21% by mass.   The tire according to any one of claims 1 to 6, wherein the urethane resin-coated region is formed in at least a part of a tire outer surface of a tread portion and / or a sidewall portion.   The tire according to any one of claims 1 to 7, wherein the urethane resin foam has an expansion ratio of 4 times or more. A method for producing a tire according to any one of claims 1 to 8,
A method for producing a tire, comprising laminating a urethane resin foam on an unvulcanized rubber surface and vulcanizing the same.