Rubber compositions for sealing materials, pneumatic tires

Abstract

This invention provides a rubber composition for sealing materials with excellent destructive properties and sealing performance, and an inflatable tire (self-healing tire) using the same. The rubber composition for sealing materials contains, relative to 100 parts by weight of butyl rubber, 5 to 20 parts by weight of a resin curing agent and 100 to 300 parts by weight of a liquid polymer.

Description

Technical Field

[0001] This invention relates to rubber compositions for sealing materials and pneumatic tires using the same. Background Technology

[0002] As a type of pneumatic tire with puncture resistance (hereinafter referred to as tire), self-sealing tires are known to have a sealing material coated on the inner surface of the tire. Self-sealing tires are tires in which the hole formed when punctured is automatically sealed by the sealing material, and various studies have been conducted on sealing materials.

[0003] Traditional sealing materials use organic peroxides such as peroxides for cross-linking (e.g., Patent Document 1).

[0004] [Existing Technical Documents]

[0005] [Patent Literature]

[0006] [Patent Document 1] Japanese Patent No. 5589182 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] However, the inventors' research results show that traditional sealing materials that use organic peroxides such as peroxides for crosslinking are difficult to control the crosslinking reaction and have uneven crosslinking structures. Therefore, there is room for improvement in terms of the destructive properties and sealing performance required for sealing materials.

[0009] The present invention solves the above-mentioned problems and aims to provide a rubber composition for sealing materials with excellent destructive properties and sealing performance, as well as an inflatable tire (self-healing tire) using the same.

[0010] [Methods used to solve problems]

[0011] This invention relates to a rubber composition for sealing materials, which, relative to 100 parts by weight of butyl rubber, contains 5 to 20 parts by weight of a resin curing agent and 100 to 300 parts by weight of a liquid polymer.

[0012] Preferably, the resin curing agent is a phenolic resin.

[0013] Preferably, the liquid polymer is liquid polybutene.

[0014] Preferably, the liquid polymer has a kinematic viscosity of 500–6000 cSt, measured at 100°C according to ASTM D445.

[0015] Preferably, in the rubber composition for sealing materials, the content of organic peroxide is less than 1 part by mass relative to 100 parts by mass of butyl rubber.

[0016] The present invention also relates to a pneumatic tire (self-healing tire) having a sealing layer made using the above-described rubber composition.

[0017] Preferably, the sealing layer has a complex elastic modulus G measured at 100°C according to ISO 13145. * The range is 0.75–3.50 kPa.

[0018] Preferably, the sealing layer has an elongation at break of 500% or more, as measured at -25°C according to JIS K 6251.

[0019] [The effects of the invention]

[0020] The sealing material rubber composition of the present invention contains 5 to 20 parts by weight of resin curing agent and 100 to 300 parts by weight of liquid polymer relative to 100 parts by weight of butyl rubber, thus providing a sealing material rubber composition with excellent destructive properties and sealing performance, as well as an inflatable tire (self-healing tire) using the same. Attached Figure Description

[0021] [ Figure 1 A schematic illustration of an example of a coating apparatus used in a method for manufacturing self-sealing tires.

[0022] [ Figure 2 ]constitute Figure 1 An enlarged view of the area near the front end of the nozzle of the coating apparatus shown.

[0023] [ Figure 3 A schematic diagram illustrating the positional relationship between the nozzle and the tire.

[0024] [ Figure 4 A schematic illustration of an example of a generally rope-like sealing material continuously spirally attached to the inner circumferential surface of a tire.

[0025] [ Figure 5 ]constitute Figure 1 An enlarged view of the area near the front end of the nozzle of the coating apparatus shown.

[0026] [ Figure 6 A schematic illustration of an example of sealing material applied to a self-sealing tire.

[0027] [ Figure 7 A schematic illustration of an example of manufacturing equipment used in a method for manufacturing self-sealing tires.

[0028] [ Figure 8Cut at point AA, which is perpendicular (or orthogonal) to the coating direction (length direction) of the sealant. Figure 4 A schematic diagram illustrating an example of the cross-section of a sealing material.

[0029] [ Figure 9 A schematic diagram illustrating an example of the cross-section of a pneumatic tire.

[0030] [Figure Labels]

[0031] 10 tires

[0032] 11. Inner circumferential surface of the tire

[0033] 14. Fetal face

[0034] 15. Fetal body

[0035] 16. Buffer layer (breaker)

[0036] 17. Band layer

[0037] 20 Sealing materials

[0038] 21 width section

[0039] 30 nozzles

[0040] 31. Nozzle tip

[0041] 40 Non-contact displacement sensor

[0042] 50 Rotary drive unit

[0043] 60 Twin-shaft compounding extruder

[0044] 61 (61a 61b 61c) Supply port

[0045] 62 Material feeder

[0046] d, d0, d1, d2: Distances between the inner circumferential surface of the tire and the tip of the nozzle. Detailed Implementation

[0047] The rubber composition (sealing material) for sealing materials of the present invention contains 5 to 20 parts by weight of a resin curing agent and 100 to 300 parts by weight of a liquid polymer, relative to 100 parts by weight of butyl rubber. Therefore, it exhibits excellent destructive properties and sealing performance.

[0048] The above-mentioned rubber composition can achieve the above-mentioned effects. Although the reason for this effect is not clear, it can be inferred as follows.

[0049] For butyl rubber, using a resin curing agent instead of organic peroxides such as peroxides ensures good destructive properties and sealing performance. This is believed to be because the resin curing agent simplifies the control of the crosslinking reaction and facilitates the formation of a uniform crosslinked structure.

[0050] Then, by adding the specific amount of liquid polymer to the butyl rubber, the specific amount of resin curing agent can be more uniformly dispersed in the composition, the crosslinking structure can be more uniform, and good destructive properties and sealing properties can be obtained.

[0051] That is, in the above composition, good destructive properties and sealing properties can be obtained through the synergistic effect of the above-mentioned specific amount of resin curing agent and the above-mentioned specific amount of liquid polymer.

[0052] The rubber composition (sealing material) for sealing materials of the present invention is suitable for parts of the inner surface of a tire, such as the tread of a self-sealing tire, where there is a possibility of puncture. Hereinafter, while describing suitable examples of a method for manufacturing a self-sealing tire, the sealing material will be described.

[0053] Self-sealing tires can be manufactured, for example, by mixing the components that make up the sealing material, preparing the sealing material, and then applying the resulting sealing material to the inner circumferential surface of the tire by means of coating or the like to form a sealing layer.

[0054] This self-sealing tire has a sealing layer on the radially inner side of the tire's inner liner.

[0055] The following are suitable examples illustrating the manufacturing method of self-sealing tires.

[0056] Self-sealing tires can be manufactured, for example, by mixing the components that make up the sealing material, preparing the sealing material, and then applying the resulting sealing material to the inner circumferential surface of the tire by means of coating or the like to form a sealing layer.

[0057] This self-sealing tire has a sealing layer on the radially inner side of the tire's inner liner.

[0058] As a sealing material, there are no particular limitations as long as it is an adhesive sealing material, and the common rubber composition used in tire puncture seals can be used. Butyl rubber is used as the main component of the rubber composition. This results in a favorable situation where good air permeability and resistance to degradation are ensured while achieving moderate flowability. Besides butyl rubber (IIR), other butyl rubbers include brominated butyl rubber (Br-IIR), chlorinated butyl rubber (Cl-IIR), and halogenated butyl rubber (X-IIR). These can be used alone or in combination. Halogenated butyl rubber is preferred because it is easier to crosslink and achieves higher crosslink density compared to unhalogenated butyl rubber, resulting in better performance. Brominated butyl rubber is more preferred because it has a higher promoting effect on the crosslinking reaction, resulting in better performance.

[0059] Based on the viewpoint that this better ensures the flowability of the sealing material, the Mooney viscosity ML1+8 of the aforementioned butyl rubber at 125°C is preferably 20 or higher, more preferably 40 or higher, and further preferably 60 or lower. When the Mooney viscosity is within this range, there is a tendency to obtain better results.

[0060] In addition, the Mooney viscosity ML1+8 at 125°C was measured as follows: According to JIS K-6300-1:2001, at a test temperature of 125°C, the residual heat time of the L-shaped rotor was set to 1 minute, and the rotor rotation time was set to 8 minutes for measurement.

[0061] The halogen content of the aforementioned halogenated butyl rubber is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and further preferably 5.0% by mass or less, more preferably 4.0% by mass or less. This results in a better promoting effect on the crosslinking reaction and thus better overall performance.

[0062] The halogen content can be determined by solution NMR.

[0063] Commercially available butyl rubber products, for example, include those from ExxonMobil, BUTYL Corporation, JSR Corporation, and Cenway Corporation.

[0064] Of the 100% by mass of rubber composition, the content of the aforementioned butyl rubber is preferably 80% by mass or more, more preferably 90% by mass or more, and may be 100% by mass. When the content is within the above range, there is a tendency to obtain better results.

[0065] In addition to the rubber components mentioned above, other diene-based rubbers such as natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR) can also be used as rubber components. These can be used alone or in combination of two or more.

[0066] As a rubber component, a rubber component containing, for example, at least one functional group with metal coordination ability in its molecular structure may be appropriately applied. Here, the functional group with metal coordination ability is not particularly limited, and examples include functional groups containing atoms with metal coordination ability such as oxygen, nitrogen, and sulfur. Specifically, examples include dithiocarbamate, phosphate, carboxylic acid, carbamate, dithiocarboxylic acid, aminophosphate, and thiol groups. Only one of the above functional groups may be present, or two or more may be present.

[0067] Furthermore, examples of coordinating metals for this functional group include Fe, Cu, Ag, Co, Mn, Ni, Ti, V, Zn, Mo, W, Os, Mg, Ca, Sr, Ba, Al, and Si. For instance, in polymer materials containing compounds with such metal atoms (M1) and functional groups (-COO, etc.) possessing metal coordination ability, each -COOM1 coordinates and overlaps, thereby forming a cluster of metal atoms. Furthermore, the amount of the aforementioned metal atom (M1) added is preferably 0.01 to 200 parts by mass relative to 100 parts by mass of the rubber component.

[0068] Commercially available products containing the aforementioned rubber components may include those from companies such as Sumitomo Chemical Co., Ltd., Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation.

[0069] The sealing material contains a liquid polymer. This allows for better assurance of adequate fluidity. As described above, by adding the specific amount of liquid polymer to butyl rubber, the specific amount of resin curing agent can be more uniformly dispersed in the composition, resulting in a more uniform cross-linking structure and good destructive properties and sealing performance.

[0070] Examples of liquid polymers used in sealing materials include liquid polybutene, liquid polyisobutylene, liquid polyisoprene, liquid polybutadiene, liquid polyalphaolefin, liquid isobutylene, liquid ethylene / alpha olefin copolymer, liquid ethylene / propylene copolymer, and liquid ethylene / butene copolymer. Among these, liquid polybutene is preferred due to its high compatibility with butyl rubbers and the resulting better performance. Examples of liquid polybutene include copolymers with a long-chain hydrocarbon molecular structure obtained by reacting n-butene with isobutylene as the main component; hydrogenated liquid polybutene can also be used. Only one type of liquid polymer can be used, or two or more can be used in combination.

[0071] The kinematic viscosity of liquid polymers such as liquid polybutene at 100°C is preferably 500 cSt or higher, more preferably 580 cSt or higher, and even more preferably 3000 cSt or higher. This kinematic viscosity at 100°C is preferably 6000 cSt or lower, more preferably 5500 cSt or lower, and even more preferably 5000 cSt or lower. When the kinematic viscosity is within the above range, better results are tended to be obtained.

[0072] The kinematic viscosity of liquid polymers such as liquid polybutene at 40°C is preferably 15,000 cSt or higher, more preferably 20,000 cSt or higher, even more preferably 25,000 cSt or higher, particularly preferably 50,000 cSt or higher, and most preferably 100,000 cSt or higher. This kinematic viscosity at 40°C is preferably 250,000 cSt or lower, more preferably 200,000 cSt or lower, and even more preferably 180,000 cSt or lower. When the kinematic viscosity is within the above range, better results are tended to be obtained.

[0073] In addition, the kinematic viscosity is a value measured according to ASTM D445 (2019) at 40°C or 100°C.

[0074] Commercially available products of the aforementioned liquid polymers include, for example, those from JXTG Energy Corporation, Nippon Oil Corporation, DAELIM Corporation, KEMAT Corporation, INEOS Corporation, etc.

[0075] The content of liquid polymer relative to 100 parts by weight of butyl rubber is 100 parts by weight or more, more preferably 120 parts by weight or more, even more preferably 140 parts by weight or more, particularly preferably 160 parts by weight or more, and most preferably 180 parts by weight or more. This content is 300 parts by weight or less, more preferably 280 parts by weight or less, even more preferably 260 parts by weight or less, particularly preferably 240 parts by weight or less, and most preferably 220 parts by weight or less. Contents within the above range tend to yield better results. When the liquid polymer content is less than 100 parts by weight, the sealing material is too hard, thus failing to guarantee a seal; when the content is more than 300 parts by weight, it is too soft, resulting in low destructive properties, and furthermore, it cannot maintain the shape of the sealing material.

[0076] Of these, it is preferable to use only one type of liquid polymer (preferably liquid polybutene) with a kinematic viscosity within the range of 100°C and 40°C, at the aforementioned content. Better results can be obtained by using this type and content of liquid polymer.

[0077] A resin curing agent is used as a crosslinking agent.

[0078] As a resin curing agent, there are no particular limitations as long as it has curing ability; examples include phenolic resins, urea resins, melamine resins, and acrylic resins. These can be used alone or in combination. Among them, phenolic resins are preferred for the purpose of obtaining better results.

[0079] Examples of phenolic resins include phenol-formaldehyde resins obtained by the condensation reaction of phenolic compounds with aldehydes such as formaldehyde, acetaldehyde, and furfural; and phenol-sulfur chloride condensates obtained by the condensation reaction of phenolic compounds with sulfur chloride. These can be used alone or in combination of two or more.

[0080] Examples of phenolic compounds include phenol; alkylphenols such as amyl phenol, pentylphenol, 1-methylbutylphenol, 2-methylbutylphenol, 3-methylbutylphenol, 1-ethylpropylphenol, 1,1-dimethylpropylphenol, 1,2-dimethylpropylphenol, 2,2-dimethylpropylphenol, 4-(1,1,3,3-tetramethylbutyl)phenol, 4-tert-octylphenol, and 4-tert-butylphenol; and alkoxyphenols such as methoxyphenol and ethoxyphenol. Halides of their bromides, etc., may also be examples. These can be used alone or in combination of two or more. Alkylphenols are preferred for better results, and 4-tert-butylphenol is more preferred.

[0081] The number of carbon atoms in the alkyl group of the alkylphenol is not particularly limited, but for the purpose of obtaining better results, it is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. There is no particular upper limit, but it is preferably 10 or less, more preferably 8 or less, even more preferably 6 or less, and particularly preferably 5 or less. When the number of carbon atoms is within the above range, there is a tendency to obtain better results. Furthermore, alkylphenols with different numbers of carbon atoms in the alkyl group can be used in combination as alkylphenols.

[0082] Among phenolic resins, phenol-formaldehyde resin and phenol-sulfur chloride condensate are preferred for the purpose of obtaining better results, and phenol-formaldehyde resin is even more preferred.

[0083] Furthermore, as a (phenol)-(form)aldehyde resin, an alkylphenol-aldehyde resin is preferred, a halogenated alkylphenol-aldehyde resin is more preferred, and a brominated alkylphenol-aldehyde resin is even more preferred, based on the fact that better results can be obtained.

[0084] Furthermore, alkylphenol-sulfur chloride condensates are preferred as phenol-sulfur chloride condensates because they can produce better results.

[0085] Commercially available products that can be used as the aforementioned resin curing agents include, for example, products from Taoka Chemical Co., Ltd., Arkema Corporation, and Hitachi Chemical Co., Ltd.

[0086] The content of resin curing agent relative to 100 parts by weight of butyl rubber is 5 parts by weight or more, more preferably 7 parts by weight or more, further preferably 9 parts by weight or more, particularly preferably 11 parts by weight or more, and most preferably 12 parts by weight or more. This content is 20 parts by weight or less, more preferably 18 parts by weight or less, further preferably 16 parts by weight or less, and particularly preferably 14 parts by weight or less. Contents within the above range tend to yield better results. When the content of resin curing agent is less than 5 parts by weight, the crosslinking reaction cannot proceed sufficiently, resulting in excessive softness and low destructive properties. Furthermore, the shape of the sealing material cannot be maintained. When the content of resin curing agent is more than 20 parts by weight, the sealing agent becomes too hard, thus failing to guarantee a seal.

[0087] As a crosslinking agent, it is preferable not to use conventionally used organic peroxides, sulfur, etc.

[0088] Examples of organic peroxides include acyl peroxides such as benzoyl peroxide, dibenzoyl peroxide, and p-chlorobenzoyl peroxide; peroxide esters such as 1-butyl peroxyacetate, tert-butyl peroxybenzoate, and tert-butyl peroxyphthalate; ketone peroxides such as methyl ethyl ketone peroxide; alkyl peroxides such as di-tert-butyl peroxybenzoate and 1,3-bis(1-butylperoxyisopropyl)benzene; hydroperoxides such as tert-butanol peroxide (tert-butyl hydrogen peroxide); dicumyl peroxide; and tert-butyl cumyl peroxide.

[0089] Commercially available products of the aforementioned organic peroxides include, for example, those from Nippon Oil Co., Ltd., Arkema Corporation, Kawaguchi Pharmaceutical Co., Ltd., Nouryon Corporation, etc.

[0090] Relative to 100 parts by weight of butyl rubber, the content of organic peroxide is preferably 1 part by weight or less, more preferably 0.5 parts by weight or less, even more preferably 0.1 parts by weight or less, particularly preferably 0.01 parts by weight or less, and most preferably 0 parts by weight. When the content is within the above range, there is a tendency to obtain better results.

[0091] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersed sulfur.

[0092] As commercially available sulfur products, products from companies such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., FLEXIS Corporation, Nippon Inkyu Corporation, and Hosoi Chemical Industry Co., Ltd. can be used.

[0093] Relative to 100 parts by weight of butyl rubber, the sulfur content is preferably 1 part by weight or less, more preferably 0.5 parts by weight or less, even more preferably 0.1 parts by weight or less, particularly preferably 0.01 parts by weight or less, and most preferably 0 parts by weight. When the content is within the above range, there is a tendency to obtain better results.

[0094] Here, sulfur content refers to the amount of sulfur from pure sulfur components such as powdered sulfur, excluding sulfur from sulfur-containing compounds such as phenol-sulfur chloride condensates.

[0095] Preferably, crosslinking aids (vulcanization accelerators) that are commonly used in the past are not used.

[0096] As a crosslinking aid (vulcanization accelerator), at least one can be selected from sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamate (salt), aldehyde-amine, aldehyde-amine, imidazoline, xanthic acid and quinoid compounds (quinoid compounds).

[0097] Examples of quinone dioxime compounds include p-benzoquinone dioxime, p-quinone dioxime, p-quinone dioxime diacetate, p-quinone dioxime dihexanoate, p-quinone dioxime dilaurate, p-quinone dioxime distearate, p-quinone dioxime dicrotonate, p-quinone dioxime dicycloalkylate, p-quinone dioxime succinate, p-quinone dioxime adipate, and p-quinone dioxime difuronate. dioximedifuroate), p-quinone dioxime dibenzoate, p-quinone dioxime di(o-chlorobenzoate), p-quinone dioxime di(p-chlorobenzoate), p-quinone dioxime di(p-nitrobenzoate), p-quinone dioxime di(m-nitrobenzoate), p-quinone dioxime di(3,5-dinitrobenzoate), p-quinone dioxime di(p-methoxybenzoate), p-quinone dioxime di(n-pentoxybenzoate), p-quinone dioxime di(m-bromobenzoate), etc.

[0098] Commercially available products that can be used as the aforementioned crosslinking aids include, for example, those from Ouchi Shinsei Chemical Co., Ltd., Fujifilm and Wako Pure Chemical Co., Ltd., Junsei Chemical Co., Ltd., and LORD Corporation.

[0099] Relative to 100 parts by weight of butyl rubber, the content of crosslinking aids such as quinone dioxime compounds is preferably 1 part by weight or less, more preferably 0.5 parts by weight or less, even more preferably 0.1 parts by weight or less, particularly preferably 0.01 parts by weight or less, and most preferably 0 parts by weight. When the content is within the above range, there is a tendency to obtain better results.

[0100] In addition, it is preferable not to use zinc oxide.

[0101] Zinc oxide can be cited as an example of previously known zinc oxide, and commercially available products include those from Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd.

[0102] The zinc oxide content is preferably 1 part by weight or less, more preferably 0.5 parts by weight or less, even more preferably 0.1 parts by weight or less, particularly preferably 0.01 parts by weight or less, and most preferably 0 parts by weight or less, relative to 100 parts by weight of butyl rubber. When the content is within the above range, better results are likely to be obtained.

[0103] The above-mentioned rubber composition may contain inorganic fillers such as carbon black, silica, barium sulfate, talc, mica, and mM2·xSiOy·zH2O (where M2 represents at least one metal selected from aluminum, calcium, magnesium, titanium, and zirconium, or its oxide, hydroxide, hydrate, or carbonate; m represents 1–5, x represents 0–10, y represents 2–5, and z represents a value in the range of 0–10); and plasticizers such as aromatic processing oils, naphthenic processing oils, and paraffinic processing oils. These may be used alone or in combination of two or more.

[0104] Specific examples of fillers represented by mM2·xSiOy·zH2O include aluminum hydroxide (Al(OH)3), aluminum oxide (Al2O3, Al2O3·3H2O(hydrate)), clay (Al2O3·2SiO2), kaolin (Al2O3·2SiO2·2H2O), pyrophyllite (Al2O3·4SiO2·H2O), bentonite (Al2O3·4SiO2·2H2O), and aluminum silicate (Al2SiO5, Al4(SiO2)3·5H2O). Calcium aluminum silicate (Al2O3·CaO·2SiO2), calcium hydroxide (Ca(OH)2), calcium oxide (CaO), calcium silicate (Ca2SiO4), calcium magnesium silicate (CaMgSiO4), magnesium hydroxide (Mg(OH)2), magnesium oxide (MgO), talc (MgO·4SiO2·H2O), attapulgite (5MgO·8SiO2·9H2O), magnesium aluminum oxide (MgO·Al2O3), titanium dioxide (TiO2), titanium black (Ti n O 2n-1 These can be used individually or in combination of two or more.

[0105] Commercially available inorganic fillers include products from companies such as Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Shin Nippon Ka Carbon Co., Ltd., Columbia Carbon Co., Ltd., Degussa Corporation, RHODIA Corporation, Tosoh Silicon Chemical Co., Ltd., Solvay Japan Co., Ltd., and Tokuyama Co., Ltd.

[0106] Commercially available plasticizers, for example, include those from Idemitsu Kosan Co., Ltd., Sankyo Oil & Chemical Co., Ltd., Nippon Energy Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Oil Co., Ltd., Fuji Kosan Co., Ltd., Nissin Oillio Group Co., Ltd., Taoka Chemical Co., Ltd., etc.

[0107] The content of inorganic filler relative to 100 parts by weight of butyl rubber is preferably 1 part by weight or more, more preferably 10 parts by weight or more, and even more preferably 20 parts by weight or more. This content is preferably 50 parts by weight or less, more preferably 40 parts by weight or less. When this content is within the above range, there is a tendency to obtain better results.

[0108] Based on the viewpoint of preventing degradation caused by ultraviolet radiation, and also based on the reason that while ensuring good elongation at break, it can better ensure reinforcement, carbon black is preferred as an inorganic filler. In this case, the carbon black content is preferably 1 part by mass or more, more preferably 10 parts by mass or more, and even more preferably 20 parts by mass or more, relative to 100 parts by mass of butyl rubber. This content is preferably 50 parts by mass or less, more preferably 40 parts by mass or less. When the content is within the above range, there is a tendency to obtain better results.

[0109] As carbon black, general carbon black used for rubber can be used appropriately. Specifically, N110, N115, N120, N121, N125, N134, N135, N219, N220, N231, N234, N293, N299, N326, N330, N335, N339, N343, N347, N351, N356, N358, N375, N539, N550, N582, N630, N642, N650, N660, N683, N754, N762, N765, N772, N774, N787, N907, N908, N990, and N991 can be used appropriately. In addition, our own synthetic products can also be used appropriately. These can be used individually, or two or more can be used together.

[0110] As a plasticizer (oil), dioctyl phthalate (DOP) is preferred because it has a lower softening temperature, which is desirable for maintaining a softened state at low temperatures.

[0111] In addition, the plasticizer described in this specification does not contain the aforementioned liquid polymer.

[0112] The content of plasticizer relative to 100 parts by weight of butyl rubber is preferably 15 parts by weight or more, more preferably 20 parts by weight or more. This content is preferably 40 parts by weight or less, more preferably 30 parts by weight or less.

[0113] In addition to the components mentioned above, additives commonly used in the tire industry, such as silane coupling agents and various antioxidants, may be further added to the rubber composition. The content of these additives is preferably 0.1 to 200 parts by weight relative to 100 parts by weight of butyl rubber.

[0114] The rubber composition (sealing material) used as a sealing material is preferably prepared by mixing butyl rubber, a specific amount of resin curing agent and a specific amount of liquid polymer, and more preferably prepared by mixing butyl rubber, a specific amount of phenol (aldehyde) resin and a specific amount of polybutene.

[0115] By mixing the above materials to prepare a sealing material, and applying the resulting sealing material to the inner circumferential surface of the tire (preferably on the inner radial side of the inner liner), a self-sealing tire with a sealing layer on the inner radial side of the inner liner can be manufactured. However, the mixing of the materials constituting the sealing material can be carried out, for example, using a known mixing machine. An example of the manufacturing equipment used in the method of manufacturing a self-sealing tire is... Figure 7 As shown.

[0116] The sealing material is applied to the inner circumferential surface of the tire, at least on the inner circumferential surface corresponding to the tread portion, and more preferably, at least on the inner circumferential surface corresponding to the buffer layer. By omitting the application of sealing material to areas where it is not necessary, self-sealing tires can be manufactured with improved productivity.

[0117] Here, the inner circumferential surface of the tire corresponding to the tread refers to the inner circumferential surface of the tire located radially inside the tread portion that contacts the road surface. Similarly, the inner circumferential surface of the tire corresponding to the buffer layer refers to the inner circumferential surface of the tire located radially inside the buffer layer. Furthermore, the buffer layer refers to a component disposed inside the tread and located radially outside the tire body; specifically... Figure 9 The components shown in the buffer layer 16, etc.

[0118] Typically, uncured tires are vulcanized using bladders. These bladders expand during vulcanization, forming a tight seal against the inner circumferential surface (inner liner) of the tire. Therefore, at the end of vulcanization, a release agent is usually applied to the inner circumferential surface (inner liner) of the tire to prevent the bladder from sticking to the inner circumferential surface (inner liner).

[0119] Water-soluble coatings or release rubbers are typically used as release agents. However, if a release agent is present on the inner circumferential surface of the tire, there is a concern that the adhesion between the sealant and the inner circumferential surface of the tire may decrease. Therefore, it is preferable to remove the release agent from the inner circumferential surface of the tire beforehand. In particular, more preferably, the release agent is removed beforehand from at least the portion of the inner circumferential surface where the sealant coating begins. Furthermore, it is even more preferable to remove the release agent beforehand from all portions of the inner circumferential surface where the sealant is applied. This further improves the adhesion of the sealant to the inner circumferential surface of the tire, allowing for the manufacture of self-sealing tires with higher sealing performance.

[0120] There are no particular limitations on the method for removing the release agent from the inner circumference of the tire, and known methods such as polishing (buffing), laser treatment, high-pressure water washing, and removal with detergent (preferably a neutral detergent) can be cited.

[0121] By continuously applying a sealant in a spiral pattern to the inner circumferential surface of the tire, the deterioration of tire uniformity can be prevented, allowing for the manufacture of self-sealing tires with excellent weight balance. Furthermore, by continuously applying the sealant in a spiral pattern to the inner circumferential surface of the tire, a uniform sealing layer can be formed in both the circumferential and width directions (especially the circumferential direction), thus enabling the stable and productive manufacture of self-sealing tires with excellent sealing performance. Additionally, the sealant is preferably applied without overlap in the width direction, and more preferably seamlessly. This further prevents the deterioration of tire uniformity while creating a more uniform sealing layer.

[0122] Furthermore, raw materials are sequentially fed into a continuous mixer (especially a twin-screw extruder), where sealing materials are sequentially prepared. The prepared sealing materials are continuously extruded from nozzles connected to the outlet of the continuous mixer (especially the twin-screw extruder), and the sealing materials are directly applied to the inner circumferential surface of the tire. This allows for the production of self-sealing tires with good manufacturability.

[0123] Preferably, the sealing layer is formed by continuously spirally applying a generally rope-like sealing material to the inner circumferential surface of the tire. This creates a sealing layer on the inner circumferential surface of the tire, consisting of a generally rope-like sealing material continuously spirally arranged along the inner circumferential surface. The sealing layer can be formed by layering sealing materials, but it is preferably formed by a single layer of sealing material.

[0124] When the sealing material is roughly in the form of a cord, a sealing layer consisting of a single layer can be formed by continuously applying the sealing material in a spiral pattern to the inner circumferential surface of the tire. Because the sealing material is roughly in the form of a cord, the applied sealing material has a certain thickness, so even a single layer can prevent the deterioration of tire uniformity, allowing for the manufacture of self-sealing tires with excellent weight balance and good sealing performance. Furthermore, since no arbitrary layers of sealing material are layered, only one layer needs to be applied, thus improving the manufacturability of self-sealing tires.

[0125] The number of times the sealing material is wrapped around the inner circumference of the tire is preferably 20 times or more, more preferably 35 times or more, and preferably 70 times or less, more preferably 60 times or less, and even more preferably 50 times or less, because it can prevent the deterioration of tire uniformity, improve manufacturability, and produce self-sealing tires with excellent weight balance and good sealing performance. Here, "2 wraps" means that the sealing material is applied to wrap around the inner circumference of the tire twice. Figure 4 In this process, the sealing material is wound 6 times.

[0126] Next, the method for applying a sealant to the inner circumferential surface of a tire will be described.

[0127] <First Implementation>

[0128] In the first embodiment, the self-healing tire can be manufactured by the following steps: Step (1): while rotating the tire and moving at least one of the tire and the nozzle in the width direction of the tire, an adhesive sealant is applied to the inner circumferential surface of the tire through the nozzle, and the distance between the inner circumferential surface of the tire and the tip of the nozzle is measured by a non-contact displacement sensor; Step (2): based on the measurement result, the distance between the inner circumferential surface of the tire and the tip of the nozzle is adjusted to a predetermined distance by moving at least one of the tire and the nozzle in the radial direction of the tire; Step (3): the sealant is applied to the inner circumferential surface of the tire with the adjusted distance.

[0129] Using a non-contact displacement sensor, the distance between the inner circumferential surface of the tire and the nozzle tip is measured, and the measurement result is fed back, thereby maintaining a fixed distance between the inner circumferential surface of the tire and the nozzle tip. Furthermore, since sealant is applied to the inner circumferential surface of the tire while maintaining this fixed distance, the thickness of the sealant can be made uniform without being affected by deviations in tire shape or unevenness at joints. In addition, since it is not necessary to input coordinate values ​​for each tire size as in the conventional method, the sealant can be applied efficiently.

[0130] Figure 1This is a schematic illustration of an example of a coating apparatus used in a method for manufacturing self-sealing tires. Furthermore, Figure 2 It constitutes Figure 1 An enlarged view of the area near the nozzle tip of the coating apparatus shown.

[0131] Figure 1 The image shows a cross-section of a portion of the tire 10 cut along the meridian (a cross-section cut in a plane that includes both the tire width and radial directions). Figure 2 The image shown is a cross-section of a portion of the tire 10 cut in a plane that includes both the circumferential and radial directions of the tire. Figure 1 and Figure 2 In the diagram, the X direction is the width direction (axial direction) of the tire, the Y direction is the circumferential direction of the tire, and the Z direction is the radial direction of the tire.

[0132] Tire 10 is disposed in a rotary drive device (not shown) that fixes and rotates the tire while simultaneously moving the tire in the width and radius directions. This rotary drive device allows for independent rotation around the tire's axle, movement in the width direction, and movement in the radius direction.

[0133] In addition, the rotary drive unit has a control mechanism (not shown) that can control the amount of movement of the tire in the radial direction. The control mechanism can control the amount of movement of the tire in the width direction and / or the rotational speed of the tire.

[0134] The nozzle 30 is mounted at the front end of an extruder (not shown) and can be inserted into the inside of the tire 10. Then, the adhesive sealing material 20 extruded from the extruder is ejected from the front end 31 of the nozzle 30.

[0135] A non-contact displacement sensor 40 is installed on the nozzle 30 to measure the distance d between the inner circumferential surface 11 of the tire 10 and the front end 31 of the nozzle 30.

[0136] Thus, the distance d measured by the non-contact displacement sensor refers to the distance between the inner circumferential surface of the tire and the tip of the nozzle in the radial direction of the tire.

[0137] In the manufacturing method of the self-healing tire of this embodiment, firstly, the tire 10 formed in the vulcanization process is mounted on a rotary drive device, and a nozzle 30 is inserted into the inside of the tire 10. Then, as... Figure 1 and Figure 2 As shown, the sealing material 20 is continuously applied to the inner circumferential surface 11 of the tire 10 by dispensing the sealing material 20 from the nozzle 30 while the tire 10 is rotated and moved in the width direction. The movement of the tire 10 in the width direction is performed along the pre-input contour shape of the inner circumferential surface 11 of the tire 10.

[0138] As described below, the sealing material 20 is preferably in a generally rope-like shape. More specifically, when the sealing material is applied to the inner circumferential surface of the tire, the sealing material is preferably kept in a generally rope-like shape, at which point the generally rope-like sealing material 20 can be continuously and spirally attached to the inner circumferential surface 11 of the tire 10.

[0139] Additionally, in this specification, "roughly rope-like" refers to a shape that is longer than it is wide and has a certain degree of width and thickness. Figure 4 This schematically illustrates an example of a generally rope-like sealing material continuously spirally adhered to the inner circumferential surface of a tire. Furthermore, Figure 8 It schematically shows that Figure 4 An example of the cross-section of a sealing material when cut with a straight line AA perpendicular to the coating direction (length direction) of the sealing material. Thus, the roughly rope-like sealing material has a certain width ( Figure 8 The length shown in the middle (W) and a certain degree of thickness ( Figure 8 (The length shown in D). Additionally, here, the width of the sealant refers to the width of the sealant after coating, and the thickness of the sealant refers to the thickness of the sealant after coating; more specifically, it refers to the thickness of the sealing layer.

[0140] The sealing material is roughly in the form of a rope or strip; specifically, it meets the thickness requirements described later (the thickness of the coated sealing material, the thickness of the sealing layer, etc.). Figure 8 The preferred numerical range of the length shown in D, and the width of the sealing material (the width of the sealing material after coating). Figure 4 The length shown in W is Figure 6 The sealing material is preferably within a preferred range of the length (as shown in W0), and more preferably, it is within a preferred range of the ratio of the thickness of the sealing material to the width of the sealing material (thickness of the sealing material / width of the sealing material) as described later. Furthermore, it may be a sealing material within a preferred range of the cross-sectional area of ​​the sealing material as described later.

[0141] In the self-healing tire manufacturing method of this embodiment, the sealing material is applied to the inner circumferential surface of the tire through the following steps (1) to (3).

[0142] <Process (1)>

[0143] like Figure 2 As shown, the distance d between the inner circumferential surface 11 of the tire 10 and the front end 31 of the nozzle 30 before the sealant 20 is applied is measured by a non-contact displacement sensor 40. The distance d is measured each time the sealant 20 is applied to the inner circumferential surface 11 of each tire 10, from the start of the application of the sealant 20 to the end of the application.

[0144] <Process (2)>

[0145] The distance d is measured and transmitted to the control mechanism of the rotary drive device. In the control mechanism, the radial movement of the tire is adjusted according to the measured data so that the distance between the inner circumferential surface 11 of the tire 10 and the front end 31 of the nozzle 30 is a specified distance.

[0146] <Process (3)>

[0147] The sealing material 20 is continuously ejected from the front end 31 of the nozzle 30, and can therefore be applied to the inner circumferential surface 11 of the tire 10, where the spacing has been adjusted. Through the above processes (1) to (3), a sealing material 20 of uniform thickness can be applied to the inner circumferential surface 11 of the tire 10.

[0148] Figure 3 This is a schematic diagram illustrating the positional relationship between the nozzle and the tire.

[0149] like Figure 3 As shown, during the movement of the nozzle 30 relative to the tire 10 to the positions shown in (a) to (d), the distance between the inner circumferential surface 11 of the tire 10 and the front end 31 of the nozzle 30 is maintained at a specified distance d0 while the sealant is applied.

[0150] For the purpose of achieving better results, the adjusted interval d0 is preferably 0.3 mm or more, and more preferably 1.0 mm or more. Furthermore, the adjusted interval d0 is preferably 3.0 mm or less, and more preferably 2.0 mm or less.

[0151] Here, the adjusted interval d0 refers to the distance in the tire radius direction between the inner circumferential surface of the tire and the front end of the nozzle after the above process (2).

[0152] Furthermore, for the purpose of achieving better results, the adjusted interval d0 is preferably 30% or less of the thickness of the coated sealant, more preferably 20% or less, and more preferably 5% or more of the thickness of the coated sealant, more preferably 10% or more.

[0153] For the purpose of achieving better results, the thickness of the sealing material (the thickness of the sealing material after coating, the thickness of the sealing layer, etc.) is important. Figure 8The length (as shown in D) is not particularly limited, but for the purpose of obtaining better results, it is preferably 1.0 mm or more, more preferably 1.5 mm or more, even more preferably 2.0 mm or more, particularly preferably 2.5 mm or more, and preferably 10 mm or less, more preferably 8.0 mm or less, even more preferably 5.0 mm or less. Furthermore, the thickness of the sealing material can be adjusted by adjusting the tire rotation speed, the tire's width-direction movement speed, and the distance between the nozzle tip and the inner circumferential surface of the tire.

[0154] The thickness of the sealing material (the thickness of the applied sealing material, the thickness of the sealing layer) is preferably substantially fixed. This further prevents the deterioration of tire uniformity and allows for the manufacture of self-sealing tires with better weight balance.

[0155] In this specification, "thickness is substantially fixed" means that the variation in thickness is controlled to be 90-110% (preferably 95-105%, more preferably 98-102%, and even more preferably 99-101%).

[0156] Because of the reduced nozzle clogging, excellent operational stability, and the potential for better results, a generally rope-like sealing material is preferred, and more preferably, the generally rope-like sealing material is spirally applied to the inner circumferential surface of the tire. However, a non-generally rope-like sealing material can be used, and the sealing material can be applied by spraying it onto the inner circumferential surface of the tire.

[0157] When using a roughly rope-like sealing material, the width of the sealing material (the width of the sealing material after coating), Figure 4 The length (as shown in W) is not particularly limited, but for the sake of obtaining better results, it is preferably 0.8 mm or more, more preferably 1.3 mm or more, and even more preferably 1.5 mm or more. In addition, the width of the sealing material is preferably 18 mm or less, more preferably 13 mm or less, even more preferably 9.0 mm or less, particularly preferably 7.0 mm or less, most preferably 6.0 mm or less, and even more preferably 5.0 mm or less.

[0158] The thickness of the sealing material (the thickness of the sealing material after coating, the thickness of the sealing layer, Figure 8 The length shown in D) and the width of the sealing material (width of the applied sealing material, Figure 4 The ratio of the length shown in W (thickness of the sealing material / width of the sealing material) is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.8 or more, particularly preferably 0.9 or more, and preferably 1.4 or less, more preferably 1.3 or less, even more preferably 1.2 or less, and particularly preferably 1.1 or less. The closer this ratio is to 1.0, the more ideal the shape of the sealing material is, resulting in a more productive self-sealing tire.

[0159] Cross-sectional area of ​​the sealing material (cross-sectional area of ​​the sealing material after coating) Figure 8 The area (calculated as D×W) is preferably 0.8 mm for better results. 2 The above, preferably 1.95mm 2 The above further optimizes the thickness to 3.0mm. 2 Of the above, 3.75mm is particularly preferred. 2 In addition, 180mm is preferred. 2 Below, 104mm is preferred. 2 Below, 45mm is further preferred. 2 The following is a preferred size: 35mm. 2 The preferred size is 25mm. 2 the following.

[0160] The width of the area where the sealant is applied (hereinafter also referred to as the width of the application area or the width of the sealant layer). Figure 4 The length shown in the figure is 6×W. Figure 6 The length (as shown in W1+6×W0) is not particularly limited, but for the sake of obtaining better results, it is preferably 80% or more of the tread contact width, more preferably 90% or more, even more preferably 100% or more, and preferably 120% or less, more preferably 110% or less.

[0161] The width of the sealing layer is preferably 85 to 115% of the width of the tire's buffer layer (the length of the buffer layer in the tire width direction) for the purpose of achieving better results.

[0162] In addition, in this specification, when multiple buffer layers are provided in the tire, the length of the buffer layer in the tire width direction refers to the length of the buffer layer with the longest length in the tire width direction among the multiple buffer layers.

[0163] In this specification, the tire contact width is defined as follows: First, under normal conditions (no load) on a tire mounted on a standard rim and inflated to the standard internal pressure, with a standard load applied and the tire contacting the ground at a camber angle of 0 degrees, the outermost contact point along the tire's axial direction is defined as the "contact point" Te. Then, the axial distance between these two contact points Te is defined as the tire contact width TW. Unless otherwise specified, the dimensions of all parts of the tire are values ​​measured under these normal conditions.

[0164] The term "standard rim" refers to the rim specified for each tire within the specification system that includes the tire's base specifications. In JATMA, it refers to "standard rim," in TRA it refers to "design rim," and in ETRTO it refers to "measuring rim." Similarly, "standard tire pressure" refers to the air pressure specified for each tire within the specification system that includes the tire's base specifications. In JATMA, it refers to "maximum air pressure," in TRA it refers to the maximum value recorded in the table "TIRELOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES," and in ETRTO it refers to "INFLATION PRESSURE." When the tire is for passenger cars, this is 180 kPa.

[0165] Furthermore, the aforementioned "regular load" refers to the load specified for each tire in each specification system, including the specifications on which the tire is based. In JATMA, it refers to "maximum load capacity," in TRA it refers to the maximum value recorded in the table "TIRE LOAD LIMITS ATVARIOUS COLD INFLATION PRESSURES," and in ETRTO it refers to "LOAD CAPACITY." When the tire is used for passenger cars, it is equivalent to 88% of the aforementioned load.

[0166] There is no particular limitation on the rotational speed of the tire when applying the sealing material. However, it is preferable to rotate at a speed of 5 m / min or more, more preferably 10 m / min or more, and preferably 30 m / min or less, more preferably 20 m / min or less, for the purpose of obtaining better results.

[0167] By using a non-contact displacement sensor, the risk of malfunctions due to sealing material adhering to the sensor can be reduced. There are no particular limitations on the non-contact displacement sensor used, as long as it can measure the distance between the inner circumferential surface of the tire and the nozzle tip; examples include laser sensors, optical sensors, and capacitance sensors. These sensors can be used individually or in combination. From the viewpoint of measuring rubber, laser sensors and optical sensors are preferred, with laser sensors being more preferred. When using a laser sensor, by irradiating the inner circumferential surface of the tire with laser light, the distance between the inner circumferential surface of the tire and the tip of the laser sensor is measured based on the reflection of the laser light. The distance between the inner circumferential surface of the tire and the nozzle tip is then subtracted from this value to obtain the distance between the inner circumferential surface of the tire and the nozzle tip.

[0168] The location of the non-contact displacement sensor is not particularly limited as long as it can measure the distance between the inner circumference of the tire before the sealant is applied and the tip of the nozzle. It is preferred to install it on the nozzle, and more preferably to place it at a location where the sealant is not attached.

[0169] Furthermore, there are no specific limitations on the number or size of non-contact displacement sensors.

[0170] Since non-contact displacement sensors are not heat-resistant, it is preferable to use heat-insulating materials or the like for protection and / or to use air or the like for cooling to prevent the thermal effects of the high-temperature sealing material ejected from the nozzle. This improves the durability of the sensor.

[0171] In the description of the first embodiment, an example of tire movement without nozzle movement was given as the movement of the tire in the width and radius directions. However, it is possible that the tire does not move while the nozzle moves, or that both the tire and the nozzle move.

[0172] Furthermore, the rotary drive preferably has a means to increase the width of the tire's bead portion. When applying sealant to the tire, increasing the width of the tire's bead portion facilitates easy application of the sealant. In particular, after mounting the tire on the rotary drive, when introducing the nozzle near the tire's inner circumferential surface, the nozzle can be introduced simply by moving it parallel to the surface, making it easy to control and improving productivity.

[0173] As a means of increasing the width of the tire bead portion, there are no particular limitations, as long as it can increase the width of the tire bead portion. Examples include devices using two sets of multiple (preferably two) rollers with their positions fixed relative to each other, and mechanisms that move separately along the tire width direction. The device is inserted into the tire from both sides of the tire opening to increase the width of the tire bead portion.

[0174] In the above manufacturing method, the sealing material, which is mixed using a biaxial compounding extruder and the cross-linking reaction within the extruder is suppressed, is directly coated onto the inner circumferential surface of the tire. Therefore, the cross-linking reaction begins from the coating stage, resulting in good adhesion to the inner circumferential surface of the tire. Simultaneously, the cross-linking reaction can proceed more effectively, allowing for the manufacture of a self-sealing tire with high sealing performance. Therefore, further cross-linking of the self-sealing tire coated with the sealing material is unnecessary, leading to good productivity.

[0175] Additionally, the following crosslinking process may be performed as needed: a crosslinking process for further crosslinking of self-healing tires coated with sealing material.

[0176] In the crosslinking process, heating the self-healing tire is preferred. This increases the crosslinking speed of the sealing material, allows for a better crosslinking reaction, and enables more productive manufacturing of the self-healing tire. The heating method is not particularly limited and known methods can be used, but an oven is preferred. In the crosslinking process, for example, the self-healing tire can be placed in an oven at 70°C to 190°C (preferably 150°C to 190°C) for 2 to 15 minutes. Furthermore, because even with freshly applied, easily flowing sealing material, the crosslinking reaction can proceed without causing flow or deterioration of uniformity, it is preferable to rotate the tire circumferentially during crosslinking. The rotation speed is preferably 300 to 1000 rpm. Specifically, for example, an oven with a rotating mechanism can be used.

[0177] Furthermore, even without a separate cross-linking process, it is preferable to rotate the tire circumferentially until the cross-linking reaction of the sealant is complete. This ensures that even freshly applied, free-flowing sealant undergoes a cross-linking reaction without causing flow or deterioration of uniformity. The rotation speed is the same as in the cross-linking process.

[0178] To improve the crosslinking speed of the sealing material, it is preferable to preheat the tire before applying the sealing material. This allows for more productive manufacturing of self-sealing tires. The preheating temperature of the tire is preferably 40°C or higher, more preferably 50°C or higher, and further preferably 100°C or lower, more preferably 70°C or lower. By setting the tire preheating temperature within the above range, the crosslinking reaction starts appropriately from the time of coating and proceeds more effectively, resulting in a self-sealing tire with high sealing performance. Furthermore, by setting the tire preheating temperature within the above range, a crosslinking process is unnecessary, thus allowing for more productive manufacturing of self-sealing tires.

[0179] Continuous mixing mills (especially twin-shaft mixing extruders) generally operate continuously. On the other hand, when manufacturing self-sealing tires, the tire needs to be replaced when the coating of one tire is finished. In this case, in order to manufacture higher quality self-sealing tires while suppressing a decline in productivity, the following methods (1) and (2) can be used. Since method (1) has the disadvantage of quality degradation and method (2) has the disadvantage of increased cost, they can be used appropriately depending on the situation.

[0180] (1) By simultaneously operating and stopping the continuous mixer and all supply devices, the supply of sealing material to the inner circumferential surface of the tire is controlled.

[0181] That is, when the coating of one tire is finished, the continuous mixer and all supply devices are stopped simultaneously, the tire is replaced (preferably within 1 minute), the continuous mixer and all supply devices are restarted, and the coating of the tire can be resumed. By changing the tire quickly (preferably within 1 minute), the degradation of quality can be suppressed.

[0182] (2) By maintaining the working position of the continuous mixer and all supply devices, and switching the flow path, the supply of sealing material to the inner circumferential surface of the tire is controlled.

[0183] That is, in a continuous mixer, a flow path different from that of the nozzles that feed directly onto the inner circumference of the tire is pre-set. At the end of coating one tire, the prepared sealing material is discharged from the other flow path until the tire is replaced. In this method, since the continuous mixer and all supply devices can be kept operational while manufacturing self-sealing tires, higher quality self-sealing tires can be produced.

[0184] Furthermore, the carcass cord used in the self-sealing tire is not particularly limited, and examples include fiber cord and steel cord. Steel cord is preferred. Particularly ideal is steel cord made of hard steel wire as specified in JIS G3506. In self-sealing tires, using high-strength steel cord instead of the commonly used fiber cord as the carcass cord significantly improves resistance to sidewall cuts (resistance to cuts to the sidewall caused by driving on curbs, etc.), and further improves the puncture resistance of the entire tire, including the sidewall.

[0185] The structure of steel cord is not particularly limited, and examples include single-twist steel cord composed of 1×n, multi-layered steel cord composed of k+m, bundled steel cord composed of 1×n, and multi-twist steel cord composed of m×n. Here, single-twist steel cord composed of 1×n refers to a single-layered steel cord obtained by twisting n filaments together. Multi-layered steel cord composed of k+m refers to a steel cord with two layers having different twist directions and twist pitches, with k filaments in the inner layer and m filaments in the outer layer. Bundled steel cord composed of 1×n refers to a bundled steel cord obtained by twisting n filaments together. Multi-twist steel cord composed of m×n refers to a multi-twist steel cord obtained by twisting m strands obtained by twisting n filaments down. n is an integer from 1 to 27, k is an integer from 1 to 10, and m is an integer from 1 to 3.

[0186] The twist pitch of the steel cord is preferably 13 mm or less, more preferably 11 mm or less, and preferably 5 mm or more, more preferably 7 mm or more.

[0187] The steel cord preferably includes at least one spiral-shaped filament. This filament allows for larger gaps in the steel cord, improving rubber permeability while maintaining elongation under low loads and preventing poor molding during vulcanization.

[0188] To improve the initial bonding properties to the rubber composition, the surface of the steel cord is preferably electroplated with brass, Zn, or the like.

[0189] The elongation of the steel cord under a 50N load is preferably 0.5% to 1.5%. More preferably, the elongation under a 50N load is 0.7% or more, and even more preferably 1.3% or less.

[0190] The preferred density of steel cord (ends) is 20 to 50 (ends / 5cm).

[0191] <Second Implementation Method>

[0192] In the first embodiment, when the sealing material is generally rope-like, it can be difficult to apply it to the inner circumferential surface of the tire. In particular, it is known that the sealing material at the beginning of the application is prone to peeling off. In the second embodiment, the self-sealing tire manufacturing method is characterized by setting the distance between the inner circumferential surface of the tire and the nozzle tip to d1. After applying the sealing material, the distance is changed to a distance d2, which is greater than d1, and the sealing material is applied again. This allows for the easy manufacture of a self-sealing tire with the following characteristics: by bringing the distance between the inner circumferential surface of the tire and the nozzle tip closer together at the beginning of application, the width of the sealing material corresponding to the beginning of application can be increased. An adhesive, generally rope-like sealing material is continuously and spirally applied to at least the inner circumferential surface of the tire corresponding to the tread portion. At least one end of the sealing material in the longitudinal direction is a width portion wider than the width of the adjacent portion in the longitudinal direction. In this self-sealing tire, by increasing the width of the sealing material corresponding to the beginning of application, the adhesion of that portion can be improved, preventing peeling of the sealing material in that portion.

[0193] Furthermore, in the description of the second embodiment, only the differences from the first embodiment are described, and the description of content that is repeated in the first embodiment is omitted.

[0194] Figure 5 It constitutes Figure 1 The enlarged view near the nozzle tip of the coating apparatus shown in the figure (a) shows the state immediately after the application of the sealant begins, and (b) shows the state after a specified time has elapsed.

[0195] Figure 5The figure shows a cross-section obtained by cutting a part of the tire 10 in a plane including the circumferential direction and the radial direction of the tire. In Figure 5 the X direction is the width direction (axial direction) of the tire, the Y direction is the circumferential direction of the tire, and the Z direction is the radial direction of the tire.

[0196] In the second embodiment, first, the tire 10 formed in the vulcanization process is set on the rotary drive device, and the nozzle 30 is inserted into the inside of the tire 10. Then, as shown in Figure 1 and Figure 5 , while rotating the tire 10 and moving the tire 10 in the width direction, the sealing material 20 is continuously applied to the inner peripheral surface 11 of the tire 10 by discharging the sealing material 20 from the nozzle 30. The movement of the tire 10 in the width direction is performed, for example, along the contour shape of the inner peripheral surface 11 of the tire 10 input in advance.

[0197] Since the sealing material 20 has adhesiveness and is substantially in a rope-like shape, it can be continuously attached spirally to the inner peripheral surface 11 of the tire 10 corresponding to the tread portion.

[0198] At this time, within a specified time period from the start of attachment, as shown in Figure 5 (a), the distance between the inner peripheral surface 11 of the tire 10 and the front end 31 of the nozzle 30 is set to d1, and the sealing material 20 is attached. Then, after the specified time has elapsed, as shown in Figure 5 (b), by moving the tire 10 in the radial direction, the above interval is changed to a distance d2 greater than the distance d1, and the sealing material 20 is attached.

[0199] In addition, before the attachment of the sealing material ends, the above interval can be changed back from the distance d2 to the distance d1, but from the viewpoints of manufacturing efficiency and tire weight balance, it is preferable that the distance is d2 until the attachment of the sealing material ends.

[0200] Furthermore, although it is preferable to keep the value of the distance d1 fixed within a specified time period from the start of attachment and keep the value of the distance d2 fixed after the specified time has elapsed, as long as the relationship d1 < d2 is satisfied, the values of the distances d1 and d2 do not have to be fixed.

[0201] The value of the distance d1 is not particularly limited, and for the reason that better effects can be obtained, it is preferably 0.3 mm or more, more preferably 0.5 mm or more, and the value of the distance d1 is preferably 2 mm or less, more preferably 1 mm or less.

[0202] The value of the distance d2 is not particularly limited, but for the purpose of obtaining better results, it is preferably 0.3 mm or more, more preferably 1 mm or more, and preferably 3 mm or less, more preferably 2 mm or less. The distance d2 is preferably the same as the adjusted interval d0 mentioned above.

[0203] In addition, in this specification, the distances d1 and d2 between the inner circumferential surface of the tire and the tip of the nozzle refer to the distances between the inner circumferential surface of the tire and the tip of the nozzle in the radial direction of the tire.

[0204] There is no particular limitation on the rotational speed of the tire when applying the sealing material. However, it is preferable to be 5 m / min or more, more preferably 10 m / min or more, and preferably 30 m / min or less, more preferably 20 m / min or less, for the purpose of obtaining better results.

[0205] Through the above procedures, the self-healing tire of the second embodiment can be manufactured.

[0206] Figure 6 This is a schematic illustration of an example of a sealing material attached to a self-healing tire according to the second embodiment.

[0207] A generally rope-like sealing material 20 is wound around the tire in the circumferential direction and continuously attached to it in a spiral shape. Furthermore, one end of the sealing material 20 in the longitudinal direction has a width portion 21 that is wider than the width of the adjacent portion in the longitudinal direction. This width portion 21 corresponds to the starting portion of the sealing material attachment.

[0208] The width of the sealing material (the width of the sealing material after coating), Figure 6 The length shown in W1 is not particularly limited, but for the purpose of obtaining better results, the width other than the width portion is preferred. Figure 6 The width of the sealing material (as shown in W0) is 103% or more, more preferably 110% or more, and even more preferably 120% or more. Furthermore, the width of the sealing material's width portion is preferably 210% or less, more preferably 180% or less, and even more preferably 160% or less, of the width excluding the width portion.

[0209] Furthermore, the width of the sealing material's width portion is preferably substantially fixed in the length direction, but there may be areas where it is substantially variable. For example, the width portion may have the following shape: the width is widest at the beginning of the attachment section, and the width narrows as it extends along the length direction. Here, in this specification, "substantially fixed width" means that the variation in width is controlled to be 90-110% (preferably 97-103%, more preferably 98-102%, and even more preferably 99-101%).

[0210] The length of the width portion of the sealing material (the length of the width portion of the sealing material after coating), Figure 6 The length shown in L1 is not particularly limited, but for the sake of obtaining better results, it is preferable to be less than 650 mm, more preferably less than 500 mm, even more preferably less than 350 mm, and particularly preferably less than 200 mm. In addition, the shorter the length of the width portion of the sealing material, the better, but when considering the control of the distance between the inner circumference of the tire and the tip of the nozzle, the limit is about 10 mm.

[0211] The width of the sealing material beyond its width portion (the width of the sealing material beyond its width portion after coating) Figure 6 The length (as shown in W0) is not particularly limited, but for the purpose of obtaining better results, it is preferably 0.8 mm or more, more preferably 1.3 mm or more, even more preferably 1.5 mm or more, and preferably 18 mm or less, more preferably 13 mm or less, even more preferably 9.0 mm or less, particularly preferably 7.0 mm or less, most preferably 6.0 mm or less, and even more preferably 5.0 mm or less. W0 is preferably the same as W above.

[0212] In addition, the width of the sealing material other than the width portion is preferably substantially fixed in the length direction, but there may be places where it is substantially not fixed.

[0213] The width of the area where the sealant is applied (hereinafter also referred to as the width of the application area or the width of the sealant layer). Figure 6 The length (as shown in W1+6×W0) is not particularly limited, but for the sake of obtaining better results, it is preferably 80% or more of the tread contact width, more preferably 90% or more, even more preferably 100% or more, and preferably 120% or less, more preferably 110% or less.

[0214] The width of the sealing layer is preferably 85 to 115% of the width of the tire's buffer layer (the length of the buffer layer in the tire width direction) for the purpose of achieving better results.

[0215] In the self-healing tire of the second embodiment, the sealing material is preferably applied in a way that does not overlap in the width direction, and more preferably applied seamlessly.

[0216] Furthermore, in the self-healing tire of the second embodiment, the other end of the sealing material in the length direction (the end corresponding to the end of the attachment) may also be a width portion that is wider than the width of the adjacent portion in the length direction.

[0217] The thickness of the sealing material (the thickness of the sealing material after coating, the thickness of the sealing layer, Figure 8The length shown in D is not particularly limited, but for the purpose of obtaining better results, it is preferably 1.0 mm or more, more preferably 1.5 mm or more, even more preferably 2.0 mm or more, particularly preferably 2.5 mm or more, and preferably 10 mm or less, more preferably 8.0 mm or less, and even more preferably 5.0 mm or less.

[0218] The thickness of the sealing material (the thickness of the applied sealing material, the thickness of the sealing layer) is preferably substantially fixed. This further prevents the deterioration of tire uniformity and allows for the manufacture of self-healing tires with superior weight balance.

[0219] The thickness of the sealing material (the thickness of the sealing material after coating, the thickness of the sealing layer, Figure 8 The length shown in D) and the width outside the width of the sealing material (the width outside the width of the coated sealing material, Figure 6 The ratio of the length shown in W0 (thickness of the sealing material / width of the sealing material excluding the width portion) is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.8 or more, particularly preferably 0.9 or more, and preferably 1.4 or less, more preferably 1.3 or less, even more preferably 1.2 or less, and particularly preferably 1.1 or less. The closer this ratio is to 1.0, the more ideal the shape of the sealing material becomes as rope-like, and the more productive the self-sealing tires with high sealing performance can be manufactured.

[0220] Cross-sectional area of ​​the sealing material (cross-sectional area of ​​the sealing material after coating) Figure 8 The area (calculated as D×W) is preferably 0.8 mm for better results. 2 The above, preferably 1.95mm 2 The above further optimizes the thickness to 3.0mm. 2 Of the above, 3.75mm is particularly preferred. 2 In addition, 180mm is preferred. 2 Below, 104mm is preferred. 2 Below, 45mm is further preferred. 2 The following is a preferred size: 35mm. 2 The preferred size is 25mm. 2 the following.

[0221] In the second embodiment, even if the viscosity of the sealing material is within the above-mentioned range, especially even if the viscosity is high, the bonding force of the portion can be improved by increasing the width of the sealing material corresponding to the beginning of the adhesion, thus preventing the sealing material in that portion from peeling off.

[0222] The self-healing tire of the second embodiment is preferably manufactured by the manufacturing method described above, but any other suitable manufacturing method may be used as long as at least one end of the sealing material can be modulated into a width portion.

[0223] The above description, especially in the description of the first embodiment, describes the case where a non-contact displacement sensor is used when applying sealing material to the inner circumferential surface of the tire. However, it is also possible to apply sealing material to the inner circumferential surface of the tire without measuring with a non-contact displacement sensor, by controlling the movement of the nozzle and / or the tire based on pre-input coordinate values.

[0224] According to the above-described manufacturing method, a self-healing tire can be manufactured having a sealing layer made of the aforementioned rubber composition for sealing materials on the inner side of the inner liner in the radial direction of the tire. Because the sealing layer of this pneumatic tire is made of the aforementioned rubber composition for sealing materials, it exhibits excellent destructive properties and sealing performance.

[0225] Preferably, the sealing layer is composed of a generally rope-like sealing material that is continuously spirally arranged along the inner circumferential surface of the tire. More preferably, the generally rope-like sealing materials arranged in a spiral configuration are seamlessly arranged without overlapping each other in the width direction.

[0226] The self-sealing tire with the above-described structure has excellent sealing performance because it has a sealing layer (composed of a roughly rope-like sealing material arranged in a continuous spiral along the inner circumferential surface of the tire) with uniform sealing material in both the tire circumferential and width directions (especially the tire circumferential direction) on the inner circumferential surface of the tire. Furthermore, due to the sealing material, tire balance is less likely to break down, reducing the deterioration of tire uniformity.

[0227] Furthermore, by making the sealing layer made of the rubber composition using the aforementioned sealing material into the structure described above, there is a tendency to obtain better results. It is speculated that this is because ensuring the uniform thickness of the sealing layer allows for better performance.

[0228] In addition, the sealing layer of the above structure can be manufactured, for example, by continuously spirally applying a generally rope-shaped sealing material to the inner circumferential surface of the tire.

[0229] The aforementioned sealing layer, according to ISO 13145 (2012), has a complex elastic modulus G measured at 100°C. * The preferred pressure is 0.75–3.50 kPa. G *More preferably, it is 1.00 or higher; further preferably, 1.25 or higher; particularly preferably, 1.50 or higher; most preferably, 1.75 or higher; even more preferably, 2.00 or higher; further preferably, 2.20 or higher; particularly preferably, 2.30 or higher; further preferably, it is 3.25 kPa or lower; further preferably, 3.00 kPa or lower; particularly preferably, 2.80 kPa or lower; and most preferably, 2.60 kPa or lower. When the complex elastic modulus is within the above range, it tends to yield better results. In addition, in this specification, the complex elastic modulus G... * The values ​​are measured at 100°C according to ISO 13145 (2012), specifically by the method described in the examples.

[0230] The elongation at break of the aforementioned sealing layer, measured at -25°C according to JIS K 6251 (2017), is preferably 500% or higher. More preferably, it is 525% or higher; even more preferably, 550% or higher; particularly preferably, 575% or higher; most preferably, 600% or higher; even more preferably, 625% or higher; and even more preferably, 650% or higher. Since a higher elongation at break is better, there is no particular upper limit, for example, 3000%. When the elongation at break is within the above range, there is a tendency to obtain better results.

[0231] In addition, in this specification, the elongation at break is a value obtained by tensile testing at -25°C according to JIS K 6251 (2017), specifically a value obtained by the method described in the examples.

[0232] In the aforementioned sealing layer, in order to increase the complex elastic modulus G * If the elongation at break is within the above-mentioned range, the above-mentioned rubber composition for sealing materials can be used to make it. In particular, for butyl rubber, a specific amount of resin curing agent and a specific amount of liquid polymer can be added.

[0233] More specifically, for butyl rubber, adding a specific amount of phenolic resin and a specific amount of liquid polybutene is sufficient.

[0234] The above-mentioned tires are suitable for use as passenger car tires, large passenger car tires, large SUV tires, truck / bus tires, two-wheeled vehicle tires, racing tires, winter tires (studless tires, snow tires, stud tires), all-season tires, run-flat tires, aircraft tires, mining tires, etc.

[0235] [Example]

[0236] The present invention is described in detail based on the embodiments, but the present invention is not limited to these embodiments.

[0237] The following describes the various chemicals used in the examples.

[0238] Butyl rubber: Bromobutyl 2255 (manufactured by ExxonMobil, Mooney viscosity ML1+8 = 46 at 125°C, halogen content: 2.0% by mass)

[0239] Carbon black: Vulcan 6 (manufactured by MahaChem, N220)

[0240] Liquid polybutene: JXTG Energy Corporation (manufactured polybutene HV1900, kinematic viscosity at 40°C 160,000 cSt, kinematic viscosity at 100°C 3,710 cSt, number average molecular weight 2,900)

[0241] Peroxide: BENZOXE (manufactured by Kawaguchi Pharmaceutical Co., Ltd., benzoyl peroxide)

[0242] Quinone crosslinking agent: VULNOC GM-P (manufactured by Ouchi Shinsei Chemical Co., Ltd., p-quinone dioxime)

[0243] Phenolic Resin 1: Vultac TB7 (manufactured by Arkema, 4-tert-butylphenol-sulfur chloride condensate)

[0244] Phenolic (formaldehyde) resin 2: TACKIROL V-200 (manufactured by Taoka Chemical Industry Co., Ltd., alkylphenol-sulfur chloride condensate)

[0245] Phenolic (aldehyde) resin 3: TACKIROL 250-1 (manufactured by Taoka Chemical Industry Co., Ltd., brominated alkylphenol-aldehyde resin)

[0246] Manufacturing of self-healing tires

[0247] According to the formula shown in Table 1, use a 3L kneading mixer to knead and process at 170°C for 60 minutes to prepare the sealing material.

[0248] Next, from a nozzle directly connected to the outlet of the internal mixer and positioned at the front end on the inner surface of the tire, a prepared sealing material (temperature 170°C, viscosity 35000 Pa·s (40°C), approximately in the shape of a rope, 3 mm thick, and 4 mm wide) is sequentially extruded onto the inner surface of a circumferentially rotating tire (205 / 55R16, preheating temperature: 40°C). Figures 1-4A sealing material is continuously and spirally coated onto the inner circumferential surface of the tire to form a 3mm thick, 180mm wide adhesion area, creating a sealing layer and manufacturing a self-healing tire. Furthermore, the viscosity of the sealing material is measured using a rotational viscometer at 40°C according to JIS K 6833.

[0249] Here, the cross-linking and curing reaction takes place by the heat generated during mixing.

[0250] The obtained test tires were used for the following evaluation, and the results are shown in Table 1.

[0251] <Dynamic Complex Elastic Modulus>

[0252] Test pieces were cut from the sealing layer of the aforementioned self-healing tire. Then, using an RPA manufactured by Alpha Technologies, the dynamic complex modulus G was determined at 100°C according to ISO 13145 (2012). * .

[0253] Tensile Test

[0254] A test piece was cut from the sealing layer of the self-healing tire described above. Then, a dumbbell-shaped test piece No. 3 was made using the test piece, and a tensile test was performed at -25°C using an Auto Graph (precision universal testing machine) manufactured by Shimadzu Corporation, according to JIS K 6251 (2017), to determine the elongation at break.

[0255] Complex elastic modulus G * At a pressure above 0.75 kPa and an elongation at break above 500%, the failure characteristics are considered excellent. In particular, when the complex elastic modulus G... * When the strength is above 0.80 kPa and the elongation at break is above 520%, it is judged to have superior destructive characteristics.

[0256] <Air tightness performance>

[0257] Using the aforementioned self-healing tires, tests were conducted on 100 tires stored in a constant temperature chamber at -25°C. Success rate of airtight sealing when driving in / pulling out long nails.

[0258] <Shape Preservation>

[0259] The self-healing tires were evaluated after being left to stand at 60°C for 5 days to accelerate deterioration. Products that maintained their seal shape and appearance were marked as qualified (0) and unqualified (×).

[0260] [Table 1]

[0261]

[0262] As shown in Table 1, compared to 100 parts by weight of butyl rubber, the examples containing 5-20 parts by weight of resin curing agent and 100-300 parts by weight of liquid polymer have excellent destructive properties and sealing performance.

Claims

1. A rubber composition for use as a sealing material, characterized in that, Relative to 100 parts by weight of butyl rubber, the rubber composition contains 5-20 parts by weight of resin curing agent and 100-300 parts by weight of liquid polymer. The resin curing agent is a phenol-sulfur chloride condensate. The liquid polymer is liquid polybutene.

2. The rubber composition for sealing materials according to claim 1, wherein, The liquid polymer has a kinematic viscosity of 500–6000 cSt, measured at 100°C according to ASTM D445.

3. The rubber composition for sealing materials according to claim 1, wherein, The content of organic peroxides is less than 1 part by mass relative to 100 parts by mass of butyl rubber.

4. A pneumatic tire, characterized in that, It has a sealing layer made using the rubber composition according to any one of claims 1 to 3.

5. The pneumatic tire according to claim 4, wherein, The sealing layer has a complex elastic modulus G* of 0.75–3.50 kPa, measured at 100°C according to ISO 13145.

6. The pneumatic tire according to claim 4 or 5, wherein, The sealing layer, according to JIS K 6251, has an elongation at break of over 500% as measured at -25°C.

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