JP2017105405A - tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire that is excellent in crack prevention property.SOLUTION: In the tire, at least part of a sidewall portion external surface and/or tread part external surface is covered with an urethane resin layer. The tire satisfies inequalities of 0.1≤B/A≤17 and 30≤L≤300, where A (MPa) represents a coefficient of elasticity of a rubber in a part covered with the urethane resin layer, B (MPa) represents a coefficient of elasticity of the urethane resin layer and L (μm) represents a thickness of the urethane resin layer.SELECTED DRAWING: None

Description

  The present invention relates to a tire.

  In general, the rubber constituting the tire surface may be deteriorated under the influence of the outside air environment such as the presence of ozone. And when deterioration of a tire surface advances, a crack etc. may arise. In order to solve such a problem, a technique is known in which a polyurethane film is formed on the tire surface to impart ozone resistance to the tire (Patent Document 1).

JP-T-2003-535762

However, in the technique described in Patent Document 1, cracks may occur on the tire surface, and further improvement in performance (crack prevention) for preventing cracks generated on the tire surface has been demanded.
Accordingly, an object of the present invention is to provide a tire excellent in crack prevention.

  Therefore, as a result of intensive studies by the present inventors, the elastic modulus of the rubber forming the outer surface of the tire, the elastic modulus of the urethane resin layer covering the rubber, and the thickness of the urethane resin layer satisfy a specific relationship. The present inventors have found that a tire excellent in crack prevention can be obtained.

That is, the present invention is a tire in which at least a part of the outer surface of the sidewall portion and / or the outer surface of the tread portion is coated with a urethane resin layer, and the elastic modulus A of the rubber of the portion coated with the urethane resin layer (MPa), the elastic modulus B (MPa) of the said urethane resin layer, and the thickness L (micrometer) of the said urethane resin layer satisfy | fill a following formula.
0.1 ≦ B / A ≦ 17
30 ≦ L ≦ 300

  The tire of the present invention is preferably a tire obtained by laminating a urethane resin foam on an unvulcanized rubber surface and vulcanizing it.

  Since the tire of the present invention has the above configuration, it is excellent in crack prevention.

The tire of the present invention has a urethane resin layer-covered portion in which at least a part of the outer surface of the sidewall portion and / or the outer surface of the tread portion is covered with the urethane resin layer.
In the present specification, the tire of the present invention in which at least a part of the outer surface of the sidewall portion and / or the outer surface of the tread portion is coated with a urethane resin layer may be simply referred to as “the tire of the present invention”. Further, the tire portion (the tire portion excluding the urethane resin layer covering portion) in the tire of the present invention may be simply referred to as “tire”.

  In the tire of the present invention, a urethane resin layer may be provided on the entire outer surface of the sidewall portion and / or the tread portion of the tire, or urethane may be provided on a part of the outer surface of the sidewall portion and / or the tread portion. A resin layer may be provided. The proportion of the urethane resin layer covering portion in the sidewall portion or tread portion of the tire of the present invention is preferably 1 to 100% with respect to the total outer surface area (100%) of the sidewall portion or tread portion of the tire. Furthermore, 50 to 100% is preferable.

(tire)
The tire is not particularly limited.For example, the tire includes a pair of bead portions and sidewall portions, and a tread portion that is continuous between both sidewall portions, and the tread portion extends at least between the left and right bead portions in a toroidal shape. A carcass of one layer, a belt arranged on the outer side in the tire radial direction of the carcass, and a tread rubber arranged on the outer side in the tire radial direction of the belt, the side wall portion covering the carcass, and a side rubber covering the carcass And tires made of

  Examples of the rubber forming the outer surface of the tire (for example, the side rubber on the outer surface of the sidewall portion and the tread rubber on the outer surface of the tread portion) include, for example, a rubber containing a rubber component, a compounding agent, etc. Rubber obtained by crosslinking a product).

  The said rubber component is not specifically limited, According to the objective, it can select suitably. Examples of the rubber component include butadiene polymer, natural rubber, epoxidized natural rubber, various butadiene rubbers, various styrene-butadiene copolymer rubbers, isoprene rubber, butyl rubber, and a bromide of a copolymer of isobutylene and p-methylstyrene. , Halogenated butyl rubber, acrylonitrile butadiene rubber, chloroprene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-isoprene copolymer rubber, styrene-isoprene-butadiene copolymer rubber, Examples include isoprene-butadiene copolymer rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluorine rubber, and urethane rubber. The said rubber component may be used individually by 1 type, and may use 2 or more types together.

  The compounding agent is not particularly limited. Xanthate vulcanization accelerators, etc.), vulcanizing agents (sulfur, etc.), anti-aging agents (amine-type anti-aging agents, phenol-type anti-aging agents, etc.), waxes (synthetic wax, natural wax, etc.), oils (aromatics) Oil, etc.), filler (silica, carbon black, alumina, calcium carbonate, etc.), silane coupling agent, organic acid compound (stearic acid, etc.), zinc oxide, reinforcing agent, softener, filler, colorant, flame retardant, Examples thereof include a lubricant, a plasticizer, a processing aid, a thermosoftening resin, and a curable resin.

The elastic modulus (storage elastic modulus) of rubber (for example, side rubber, tread rubber, etc.) constituting the outer surface of the sidewall part and / or the outer surface of the tread part (sometimes referred to as “rubber elastic modulus” in this specification) Although not particularly limited, for example, 1 to 20 MPa is preferable, and 3 to 15 MPa is more preferable, from the viewpoint of further improving crack prevention properties and peeling prevention properties.
The rubber elastic modulus is a value measured by the method described in (Evaluation) (Rubber elastic modulus) described later. The rubber elastic modulus can be adjusted by, for example, the type and ratio of the rubber component, the rubber composition, and the like.

(Urethane resin layer)
The urethane resin layer provided on at least a part of the outer surface of the sidewall part and / or the outer surface of the tread part may be a urethane resin layer having the same composition on the entire surface, or urethane formed by urethane resins having different compositions. It may be a collection of resin layers. Especially, it is preferable that the whole surface is a urethane resin layer of the same composition from a viewpoint of cost and manufacturing efficiency.
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).

As the urethane resin, for example, a two-component curable urethane resin prepared from a polyol and an isocyanate is preferable.
Examples of the polyol include low molecular polyols and high molecular polyols. Examples of the low molecular polyol include ethylene glycol, propylene glycol, 1,4-butanediol, glycerol, trimethylolpropane, 1,2,6-hexanetriol, erythritol, sorbitol and the like. Examples of the polymer polyol include polyoxyethylene glycol, polyoxyethylene glyceryl ether, polyoxyethylene trimethylolpropane ether, polyoxyethylene sorbitol ether, polyoxypropylene bisphenol A ether, polyoxypropylene glycol, and polyoxypropylene glyceryl. Ether, polyoxypropylene trimethylolpropane ether, polyoxypropylene sorbitol ether, polyoxyethylene-polyoxypropylene glycol, polyoxyethylene-polyoxypropylene glyceryl ether, polyoxyethylene-polyoxypropylene trimethylolpropane ether, polyoxyethylene -Polyoxypropylene sorbitol ether, polyoxyethylene Polyether polyols such as polyoxyalkylene-polyols such as ethylene-polyoxypropylene bisphenol A ether; polyhydric alcohols such as ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, neopentyl glycol, and trimethylolpropane; , Phthalic acid, maleic acid, malonic acid, succinic acid, adipic acid, condensates of polycarboxylic acids such as terephthalic acid, having a hydroxyl group at the terminal, the polyhydric alcohol, γ-butyrolactone, δ A polyester-based polyol such as a ring-opening polymerization product with a cyclic lactone such as valerolactone and ε-caprolactone and having a hydroxyl group at the terminal; Specific examples of the polyester polyol include polyethylene adipate polyol, polybutylene adipate polyol, polyethylene / butylene adipate polyol, and polyethylene terephthalate polyol. The said polyol may be used individually by 1 type, and may use 2 or more types together.
Examples of the isocyanate include organic isocyanates having two or more isocyanate groups in one molecule. For example, 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, dicyclohexylmethane diisocyanate, xylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate. , O-toluidine diisocyanate, naphthylene diisocyanate, xylylene diisocyanate, lysine diisocyanate, polymethylene polyphenylene polyisocyanate, hexamethylene diisocyanate, 4,4′-diphenylmethane diisocyanate, tolylene diene Isocyanate, xylene diisocyanate, o-toluidine diisocyanate, Diisocyanate, xylylene diisocyanate Nto, aromatic isocyanates such as polymethylene polyphenylene polyisocyanate is preferred. Further, it is particularly preferable to use 4,4′-diphenylmethane diisocyanate (MDI) and / or tolylene diisocyanate (TDI). In the case of using both, the ratio of parts by weight of TDI / parts by weight of MDI can be used in an arbitrary range, but the range of 0.05 to 20 is preferable, and the range is 0.2 to 5. Is more preferable.

  Although the ratio of the urethane resin in the said urethane resin layer is not specifically limited, From a viewpoint which a crack prevention property and peeling prevention property improve further, it is 0.1-100 mass% with respect to 100 mass% of urethane resin layers, for example. Is more preferable, and it is 50-100 mass% more preferably. Moreover, it is preferable that the resin component in the said urethane resin layer is only a urethane resin (it does not contain other resin) from a viewpoint of the balance of a mechanical characteristic with the rubber | gum of the sidewall part outer surface.

The elastic modulus (storage elastic modulus) of the urethane resin layer (which may be referred to as “urethane elastic modulus” in the present specification) is, for example, 1 to 100 MPa from the viewpoint of further improving crack prevention and peeling prevention. Is preferable, and more preferably 3 to 50 MPa.
The urethane elastic modulus is a value measured by the method described in (Evaluation) (urethane elastic modulus) described later. The urethane elastic modulus can be adjusted by, for example, the composition and ratio of the urethane resin, the thickness of the urethane resin layer, and the like.

The thickness of the urethane resin layer is 30 to 300 μm, and for example, 50 to 300 μm is preferable, and 70 to 150 μm is more preferable from the viewpoint of further improving crack prevention properties and peeling prevention properties.
Among them, from the viewpoint of further improving the crack preventing property and the peeling preventing property and further improving the strength of adhesion between the rubber forming the sidewall portion outer surface and / or the tread portion outer surface and the urethane resin layer, 1/3 < In the case of the rubber elastic modulus / the urethane elastic modulus, the urethane resin layer is preferably thicker than 40 μm. When the rubber elastic modulus / the urethane elastic modulus ≦ 1/3, the thickness of the urethane resin layer is 30. It is preferably ˜40 μm.

(Tire manufacturing method of the present invention)
The method for producing the tire of the present invention is not particularly limited. For example, (i) a method in which a urethane resin sheet is laminated on the surface of an unvulcanized rubber (unvulcanized tire) and vulcanized, and (ii) unvulcanized Method of laminating urethane resin foam on the surface of rubber (unvulcanized tire) and vulcanizing, (iii) On the outer surface of vulcanized rubber (vulcanized tire) (for example, on the outer surface of the sidewall portion and / or the tread) (Iv) a method of applying a urethane resin-containing solution to the outer surface and drying it, and (iv) on the outer surface of the vulcanized rubber (vulcanized tire) (for example, on the outer surface of the sidewall portion and / or on the outer surface of the tread portion). And a method of laminating a urethane resin sheet. Among these, from the viewpoint of improving the strength of adhesion between the sidewall portion outer surface and / or the tread portion outer surface and the urethane resin layer, (ii) a urethane resin foam is laminated on the unvulcanized rubber surface and vulcanized. The method is preferred.

  In said (i), the said urethane resin sheet (film) can apply | coat the composition containing the said urethane resin on a peeling film, for example, and can manufacture it by photocuring or thermosetting. The urethane resin sheet may further contain other resins (for example, the other resins described above).

  The thickness of the urethane resin sheet is not particularly limited, but is preferably 30 to 400 μm, more preferably 50 to 300 μm, for example, from the viewpoint of ozone resistance and a further improvement in peel prevention.

  In the urethane resin sheet, it is difficult for air bubbles to enter between the outer surface of the sidewall part and / or the outer surface of the tread part and the urethane resin layer, and the outer surface of the sidewall part and / or the outer surface of the tread part and the urethane resin layer. From the viewpoint of improving the bonding strength, for example, a hole penetrating the urethane resin sheet may be provided.

  In the above (i), the vulcanization method is not particularly limited. For example, the urethane resin sheet and unvulcanized rubber (for example, a sidewall portion and / or a tread portion of an unvulcanized tire) are formed on the inner surface of a mold. ) And vulcanization molding.

  In said (i), as vulcanization temperature, 140-200 degreeC is mentioned, for example. Moreover, as vulcanization | cure time, 5 to 60 minutes are mentioned, for example.

  In the above (ii), 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 forming the urethane resin foam may further contain other resins (for example, the above-mentioned other resins), a surfactant, a solvent / filler, and the like.

  In the above (ii), examples of the urethane resin in the urethane resin foam include those described above.

  In the above (ii), examples of the foaming agent (foaming gas) include water, hydrocarbon compounds (propane, butane, pentane, etc.), carbon dioxide gas, nitrogen gas, air and the like.

  In the above (ii), the cell structure of the urethane resin foam is not particularly limited, but it is difficult for bubbles to enter between the outer surface of the sidewall part and / or the outer surface of the tread part and the urethane resin layer, and the sidewall part. From the viewpoint of improving the strength of adhesion between the outer surface and / or the outer surface of the tread portion and the urethane resin layer, for example, a semi-continuous semi-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 preferred.

In the above (ii), the expansion ratio of the urethane resin foam is not particularly limited. From the viewpoint of improving the strength of adhesion between the sidewall portion outer surface and / or the tread portion outer surface and the urethane resin layer, for example, 50 times or less is preferable, More preferably, it is 35 times or less, More preferably, it is 20 times or less, Most preferably, it is 19 times or less.
The expansion ratio refers to “density before foaming / density after foaming”. In addition, the volume of a foam means the volume measured based on JISK7222. The expansion ratio can be adjusted by, for example, the composition and ratio of the urethane resin, the type and ratio of the foaming agent, and the foaming conditions.

In the above (ii), the density of the urethane resin foam is not particularly limited, but is 3 to 150 kg from the viewpoint of improving the adhesion strength between the sidewall portion outer surface and / or the tread portion outer surface and the urethane resin layer. / M ³ is preferable, and more preferably ³ to 100 kg / m ³ .
In addition, the said density says the value measured based on JISK6402. The said density can be adjusted with the kind and ratio of a foaming agent, foaming conditions, etc., for example.

  Examples of the vulcanization method, vulcanization temperature, and vulcanization time in (ii) above include those described above.

  In said (iii), the said urethane resin containing solution is although it does not specifically limit, For example, it can prepare by mixing the said urethane resin, a solvent, etc. uniformly. The urethane resin-containing solution may further contain another resin (for example, the other resin described above).

In the above (iii), examples of the urethane resin in the urethane resin-containing solution include those described above.
Although content of the urethane resin in the said urethane resin containing solution is not specifically limited, For example, 70-100% is preferable with respect to 100 mass% of urethane resin containing solutions, More preferably, it is 90-100%.

  In said (iii), as drying conditions of the said urethane resin containing solution, 30-150 degreeC and the conditions for 10 to 100 minutes are mentioned, for example.

  Examples of the urethane resin sheet in the above (iv) are the same as those described above. In the above (iv), after laminating the urethane resin sheets, heating (for example, heating at 100 to 250 ° C. for 0.1 to 1 minute) may be performed.

(Physical properties of the tire of the present invention)
In the tire of the present invention, the elastic modulus A (MPa) of the rubber covered with the urethane resin layer, the elastic modulus B (MPa) of the urethane resin layer, and the thickness L (μm) of the urethane resin layer are The tire satisfies the following formula.
0.1 ≦ B / A ≦ 17
30 ≦ L ≦ 300
If the B / A is higher than 17, an elastic difference between the urethane resin and the rubber is generated, and it is easy to break, so that sufficient crack resistance cannot be ensured. On the other hand, if B / A is lower than 0.1, the effect of suppressing deformation of the crack tip is small, which is not preferable.
On the other hand, when the L is thinner than 30 μm, ozone diffuses and attacks the rubber to easily cause cracks. On the other hand, if it is thicker than 300 μm, the properties of the urethane resin affect the motion performance of the tire, which is not preferable.
In the tire of the present invention, the relationship between the elastic modulus A and the elastic modulus B is, for example, preferably 0.1 <B / A <13, more preferably, from the viewpoint of further improving crack prevention properties and peeling prevention properties. Is 0.5 <B / A <10.

  The tire of the present invention is not particularly limited, but can be used as tires 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 based on examples, but the present invention is not limited to these examples.

Example 1
A urethane resin-containing solution is applied on the entire outer surface of the sidewall portion and tread portion of a commercially available vulcanized tire (tire size: 195 / 65R15), dried at 145 ° C. for 30 minutes, and then the sidewall portion and tread portion of the tire. A urethane resin-coated tire having a urethane resin layer having a thickness of 100 μm on the outer surface of the part was manufactured. The measurement of rubber elastic modulus and the evaluation of crack prevention were performed at the side wall portion.

(Example 2)
A urethane resin-coated tire was produced in the same manner as in Example 1 except that the thickness of the urethane resin layer was 30 μm. The measurement of rubber elastic modulus and the evaluation of crack prevention were performed at the side wall portion.

(Example 3)
A urethane resin foam having an open cell structure with a thickness of 1 mm, a firing ratio of 10 times, and a density of 100 kg / m ³ is laminated on the entire outer surface of the sidewall portion and the tread portion of the unvulcanized tire, and 160 ° C., 15 The urethane resin-coated tire having a urethane resin layer having a thickness of 110 μm on the outer surfaces of the sidewall portion and the tread portion of the tire was manufactured by vulcanization under the conditions of minutes. The measurement of rubber elastic modulus and the evaluation of crack prevention were performed at the side wall portion.

Example 4
A urethane resin-coated tire was manufactured in the same manner as in Example 1 except that the urethane resin-containing solution was changed and the thickness of the urethane resin layer was 35 μm. The measurement of rubber elastic modulus and the evaluation of crack prevention were performed at the side wall portion.

(Example 5)
A urethane resin-coated tire having a urethane resin layer thickness of 46 μm was produced in the same manner as in Example 3 except that the elastic modulus of the urethane resin layer was changed. The measurement of rubber elastic modulus and the evaluation of crack prevention were performed at the side wall portion.

(Example 6)
A urethane resin-coated tire was produced in the same manner as in Example 1 except that the thickness of the urethane resin layer was 40 μm. The rubber elastic modulus was measured and the crack prevention property was evaluated at the tread portion.

(Example 7)
In the same manner as in Example 3, a urethane resin-coated tire having a urethane resin layer thickness of 110 μm was manufactured. The rubber elastic modulus was measured and the crack prevention property was evaluated at the tread portion.

(Example 8)
A urethane resin-coated tire was produced in the same manner as in Example 1 except that the urethane resin-containing solution was changed and the thickness of the urethane resin layer was 40 μm. The rubber elastic modulus was measured and the crack prevention property was evaluated at the tread portion.

Example 9
In the same manner as in Example 3, a urethane resin-coated tire having a urethane resin layer thickness of 300 μm was manufactured. The rubber elastic modulus was measured and the crack prevention property was evaluated at the tread portion.

(Comparative Example 1)
A urethane resin-coated tire was produced in the same manner as in Example 1 except that the thickness of the urethane resin layer was 20 μm. The measurement of rubber elastic modulus and the evaluation of crack prevention were performed at the side wall portion.

(Comparative Example 2)
A urethane resin-coated tire was produced in the same manner as in Example 1 except that the urethane resin-containing solution was changed and the thickness of the urethane resin layer was 10 μm. The measurement of rubber elastic modulus and the evaluation of crack prevention were performed at the side wall portion.

(Comparative Example 3)
A urethane resin-coated tire was produced in the same manner as in Example 1 except that the urethane resin-containing solution was changed and the thickness of the urethane resin layer was 500 μm. The rubber elastic modulus was measured and the crack prevention property was evaluated at the tread portion.

(Comparative Example 4)
The same tire as in Example 1 was used without any coating. The measurement of rubber elastic modulus and the evaluation of crack prevention were performed at the side wall portion.

[Evaluation]
The urethane resin-coated tires or tires obtained in Examples and Comparative Examples were subjected to the following measurements and evaluations.

(Rubber elastic modulus)
The urethane resin layer was peeled off from the urethane resin-coated tire or tire sidewall or tread surface obtained in the Examples and Comparative Examples, and a rubber piece having a width of 5 mm, a length of 40 mm, and a thickness of 2 mm was cut out, and a spectrometer (Toyo Seiki Co., Ltd., rubber elastic modulus (the outer surface of the sidewall or tread part) under the conditions of 10 mm chuck distance, 150 μm initial strain, 1% dynamic strain, frequency 52 Hz, and measurement temperature 30 ° C. The elastic modulus, MPa).

(Urethane elastic modulus)
The urethane resin was processed under the same conditions as in Examples and Comparative Examples, and the elastic modulus of the urethane resin after processing was measured.

(Urethane resin layer thickness)
Cross sections of the urethane resin-coated tires or tires obtained in the examples and comparative examples were cut out, the thicknesses of the urethane resin layers at five locations were measured with an optical microscope, and the average value was taken as the thickness of the urethane resin layer.

(Crack prevention)
The urethane resin-coated tires or tire sidewalls or tread parts obtained in the examples and comparative examples were cut out and measured with a Suga tester ozone weather meter (trade name “OMS-H” manufactured by Suga Tester Co., Ltd.). . Measurement conditions were carried out according to JIS K6259 at 40 ° C., 30%, and 50 pphm. The size of the crack at that time was observed, and the ozone crack after 7 days was evaluated according to the following criteria according to the above JIS. In addition, evaluation of crack prevention property was performed in the same site | part (tread part or sidewall part) as the site | part which measured the rubber elastic modulus.
0: No crack 1: Invisible to the naked eye but can be observed with a 10 × magnifier 2: Observable with the naked eye 3: Cracks are deep and relatively large (less than 1 mm)
4: Cracks are deep and large (1 mm to 3 mm)
5: Those that are likely to cause cracks or cuts of 3 mm or more

Claims (2)

A tire in which at least part of the outer surface of the sidewall part and / or the outer surface of the tread part is coated with a urethane resin layer,
The elastic modulus A (MPa) of the rubber covered with the urethane resin layer, the elastic modulus B (MPa) of the urethane resin layer, and the thickness L (μm) of the urethane resin layer satisfy the following formula: A characteristic tire.
0.1 ≦ B / A ≦ 17
30 ≦ L ≦ 300   The tire according to claim 1, which is obtained by laminating a urethane resin foam on an unvulcanized rubber surface and vulcanizing.