Sealant composition and tire using the same

Abstract

To address the problem that conventional technology lacks satisfactory sealing performance for a penetration hole formed when a foreign object such as a nail penetrates a tread portion.SOLUTION: A sealant composition is a two-component curable system comprising: (i) a silanol-terminated polydimethylsiloxane having at least two hydroxyl functional groups per molecule; (ii) a crosslinking agent; (iii) a condensation catalyst selected from the group consisting of titanate and / or zirconate; (iv) a filler; and (v) a hollow body having a true specific gravity of 0.3 or less and an average particle diameter of 20 μm to 200 μm, wherein an amount of the hollow body is 0.1 to 100 pts.mass relative to 100 pts.mass of the component (i) silanol-terminated polydimethylsiloxane.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sealant composition and a tire using the same. [Background technology]

[0002] A known pneumatic tire has a sealant layer provided radially inward of an inner liner layer in the tread portion of the tire. In such a pneumatic tire, when a foreign object such as a nail penetrates the tread portion, the sealant composition flows into the through-hole, thereby exerting sealing properties and suppressing a decrease in air pressure, thereby enabling the tire to continue running. The sealant material compositions are disclosed in, for example, Patent Documents 1 to 4 listed below. Furthermore, Patent Document 5 below discloses a foam sealing compound containing a sealing gel, a resin, and a natural or synthetic rubber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5646474 [Patent Document 2] Patent No. 5651109 [Patent Document 3] Patent No. 5525522 [Patent Document 4] Patent No. 5738897 [Patent Document 5] Special Publication No. 2020-507640 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned conventional technology has room for improvement in sealing performance for through holes formed when a foreign object such as a nail penetrates the tread portion. Specifically, to improve sealing performance, the sealant composition needs to flow into the through holes and have appropriate flow properties so that it does not flow toward the center of the tire tread in the width direction when the tire is running. However, the conventional technology has not been able to meet this requirement, and improvement is needed. An object of the present invention is to provide a sealant composition that can solve the above problems and also reduce road noise by having sound absorption properties, and a tire using the same. [Means for solving the problem]

[0005] As a result of extensive research, the present inventors have discovered that the above-mentioned problems can be solved by a sealant composition in which hollow bodies having specific true specific gravity and average particle size are blended with a rubber component having a specific composition, and have been able to complete the present invention.

[0006] That is, the present invention provides a sealant material composition for forming a sealant layer of a pneumatic tire having a sealant layer on the inner surface of the tire, comprising: (i) at least one silanol-terminated polydimethylsiloxane having at least two hydroxyl functional groups per molecule; (ii) silanes having at least two hydrolyzable groups or at least three hydrolyzable groups per molecule, and silyl-functional molecules having at least two silyl groups, each silyl group containing at least two hydrolyzable groups or at least three hydrolyzable groups; and at least one cross-linking agent selected from the group (iii) a condensation catalyst selected from the group of titanates and / or zirconates; (iv) a filler; and (v) a hollow body having a true specific gravity of 0.3 or less and an average particle size of 20 μm to 200 μm; Including, The sealant material composition is a two-component curing type in which the (iii) and the (iv) are not stored together before use, The blending amount of the hollow bodies is 0.1 to 100 parts by mass per 100 parts by mass of the (i) silanol-terminated polydimethylsiloxane. The present invention provides a sealant material composition characterized by the above-mentioned. The present invention also provides a tire using the sealant material composition. [Effects of the Invention]

[0007] The sealant material composition of the present invention comprises: (i) at least one silanol-terminated polydimethylsiloxane having at least two hydroxyl functional groups per molecule; (ii) silanes having at least two hydrolyzable groups or at least three hydrolyzable groups per molecule, and silyl-functional molecules having at least two silyl groups, each silyl group containing at least two hydrolyzable groups or at least three hydrolyzable groups; and at least one cross-linking agent selected from the group (iii) a condensation catalyst selected from the group of titanates and / or zirconates; (iv) a filler; and (v) a hollow body having a true specific gravity of 0.3 or less and an average particle size of 20 μm to 200 μm; Including, The sealant material composition is a two-component curing type in which the (iii) and the (iv) are not stored together before use, The blending amount of the hollow bodies is 0.1 to 100 parts by mass per 100 parts by mass of the (i) silanol-terminated polydimethylsiloxane, so that the hollow bodies easily flow into holes formed when foreign objects such as nails penetrate the tread, and have appropriate flow properties that prevent them from flowing toward the center of the tire tread width direction during tire operation. This results in excellent sealing properties. Furthermore, the blending of hollow bodies with specific true specific gravity and average particle size imparts sound absorption properties to the tire, thereby reducing road noise. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 10 is a diagram for explaining measurement of the amount of deformation. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will now be described in further detail. The composition containing the above (i) to (iv) used in the present invention is known and is disclosed, for example, in Japanese Patent No. 7248865. The composition containing the above (i) to (iv) will be outlined below.

[0010] The polymer (i) used in the present invention is at least one silanol-terminated polydimethylsiloxane having at least two hydroxyl functional groups per molecule. Typically, the silanol-terminated polydimethylsiloxane has a viscosity on the order of 1,000 to 300,000 mPa·s, alternatively 1,000 to 250,000 mPa·s, at 23°C, as measured using a Brookfield cone-plate viscometer (RV DIII) with the cone-plate best suited for the viscosity of interest. In one embodiment, polymers of the above type have a viscosity of 30,000 to 200,000 mPa·s at 23° C., alternatively 45,000 to 175,000 mPa·s, alternatively 50,000 to 150,000 mPa·s at 23° C., when measured using a Brookfield cone and plate viscometer (RV DIII) using the spindle optimal for the viscosity involved, e.g., a CP-51 or CP-52 spindle, at 0.1 to 5 rpm.

[0011] The crosslinking agent (ii) used in the present invention is - silanes with at least two hydrolyzable groups per molecular group, or alternatively at least three hydrolyzable groups, and / or - a silyl-functional molecule having at least two silyl groups, each silyl group containing at least two hydrolyzable groups, alternatively at least three hydrolyzable groups; is selected from.

[0012] Silane-type crosslinkers (ii) having two hydrolyzable groups may be considered chain extenders, but can be used for crosslinking when polymer (i) has three or more reactive groups per molecule. Thus, crosslinker (ii) may have two, or alternatively three or four, silicon-bonded condensable groups (preferably hydroxyl groups and / or hydrolyzable groups) per molecule that are reactive with the condensable groups in polymer (i).

[0013] A silyl-functional molecule is one that contains two or more silyl groups, each of which contains at least two hydrolyzable groups, or alternatively, at least three hydrolyzable groups. Thus, a disilyl-functional molecule contains two silicon atoms, each of which has at least one hydrolyzable group, separated by an organic or siloxane polymer backbone. Typically, the silyl groups on the disilyl-functional molecule may be terminal groups.

[0014] Disilanes are silyl-functional molecules that have at least two silyl groups, the two silicon atoms of which are bonded to one another.

[0015] Hydrolyzable groups on silyl groups include acyloxy groups (e.g., acetoxy, octanoyloxy, and benzoyloxy); ketoximino groups (e.g., dimethylketoximo and isobutylketoximino); alkoxy groups (e.g., methoxy, ethoxy, and propoxy), and alkenyloxy groups (e.g., isopropenyloxy and 1-ethyl-2-methylvinyloxy).

[0016] Silane crosslinkers (ii) include alkoxy-functional silanes, oximosilanes, acetoxysilanes, acetoneoximesilanes, and / or enoxysilanes.

[0017] When the crosslinker is a silane and the silane has three silicon-bonded hydrolyzable groups per molecule, the fourth group is preferably a non-hydrolyzable silicon-bonded organic group. These silicon-bonded organic groups are preferably hydrocarbyl groups optionally substituted with halogens such as fluorine and chlorine. Examples of such fourth groups include alkyl groups (e.g., methyl, ethyl, propyl, and butyl); cycloalkyl groups (e.g., cyclopentyl and cyclohexyl); alkenyl groups (e.g., vinyl and allyl); aryl groups (e.g., phenyl and tolyl); aralkyl groups (e.g., 2-phenylethyl), and groups obtained by replacing all or part of the hydrogen atoms in the aforementioned organic groups with halogens. The fourth silicon-bonded organic group may be a methyl group.

[0018] A typical silane is represented by the formula (3): R'' 4-r Si(OR 5 ) r (3) [In the formula, R 5 is an organic group such as a hydrocarbyl group having 1 to 10 carbon atoms, optionally substituted with one or more halogen groups such as chlorine or fluorine; r has a value of 2, 3, or 4. Typical silanes are those in which R" represents methyl, ethyl, vinyl, or isobutyl. R" is an organic group selected from linear and branched alkyl, allyl, phenyl, and substituted phenyl, acetoxy, and oxime. In some cases, R 5 represents methyl or ethyl, and r is 3.

[0019] Another type of suitable crosslinker (ii) is Si(OR 5 )4[wherein, R 5 is as above, or is propyl, ethyl or methyl. 5 Partial condensates of 4 are also possible.

[0020] In one embodiment, crosslinker (ii) is a silyl-functional molecule having at least two silyl groups, each silyl group having at least two hydrolyzable groups. Crosslinker (ii) may additionally comprise a silyl-functional molecule having at least two silyl groups, some or all of which contain only one hydrolyzable group.

[0021] The silyl (e.g., disilyl)-functional crosslinker (ii) may have a siloxane or organic polymer backbone. For such siloxane or organic crosslinkers, the molecular structure may be linear, branched, cyclic, or macromolecular; i.e., the silicone or organic polymer chain having an alkoxy-functional end group comprises a polydimethylsiloxane having at least one trialkoxy end group, the alkoxy group being either a methoxy or ethoxy group. For siloxane-based polymers, the crosslinker viscosity is in the range of 0.5 mPa·s to 80,000 mPa·s at 23°C using a Brookfield cone-plate viscometer (RV DIII) (measured in the same manner as for polymer (i)). While any of the above hydrolyzable groups are suitable, the hydrolyzable group is preferably an alkoxy group, and as such, the terminal silyl group may be -R a Si(OR b )2, -Si(OR b )3, -R a 2SiOR b or -(R a )2Si-R c -SiR d p (OR b ) 3-p [In the formula, each R a independently represent a monovalent hydrocarbyl group, such as an alkyl group, especially one having 1 to 8 carbon atoms (preferably methyl), and each R b and R d The groups are independently alkyl groups having up to 6 carbon atoms, and R cis a divalent hydrocarbon group which may be interrupted by one or more siloxane spacers having up to six silicon atoms, and p is a value of 0, 1, or 2. Typically, each terminal silyl group has two or three alkoxy groups.

[0022] Crosslinker (ii) is a disilyl-functional polymer, i.e., a polymer containing two silyl groups, each containing at least two hydrolyzable groups, or alternatively at least three hydrolyzable groups, such as a polymer of formula (4): (R 4 O) m (Y 1 ) 3-m -Si(CH2) x -((NHCH2CH2) t -Q(CH2) x ) n -Si(OR 4 ) m (Y 1 ) 3-m (4) [In the formula, R 4 is C 1~10 is an alkyl group, and Y 1 is an alkyl group having 1 to 8 carbon atoms; Q is a chemical group containing a heteroatom having a lone pair of electrons, such as an amine, an N-alkylamine, or a urea; each x is an integer from 1 to 6; t is 0 or 1; each m is independently 2 or 3; and n is 0 or 1.

[0023] Examples of disilyl polymer crosslinkers (ii) having silicone or organic polymer chains with alkoxy-functional end groups include 1,6-bis(trimethoxysilyl)hexane (also known as hexamethoxydisilylhexane, HMSH), polydimethylsiloxanes having at least one trialkoxy end group (the alkoxy group can be a methoxy or ethoxy group).

[0024] Thus, examples of the crosslinking agent (ii) include alkyltrialkoxysilanes such as methyltrimethoxysilane (MTM) and methyltriethoxysilane, tetraethoxysilane, partially condensed tetraethoxysilane, alkenyltrialkoxysilanes such as vinyltrimethoxysilane and vinyltriethoxysilane, and isobutyltrimethoxysilane (iBTM). Other suitable silanes include ethyltrimethoxysilane, vinyltriethoxysilane, phenyltrimethoxysilane, alkoxytrioximosilane, alkenyltrioximosilane, 3,3,3-trifluoropropyltrimethoxysilane, methyltriacetoxysilane, vinyltriacetoxysilane, ethyltriacetoxysilane, dibutoxydiacetoxysilane, phenyl-tripropionoxysilane, methyltris(methylethylketoximo)silane, vinyl-tris-methylethylketoximo)silane, methyltris(methylethylketoximino)silane, methyltris(isopropenoxy)silane, vinyltris(isopropenoxy)silane, ethylpolysilicate, n-propylorthosilicate, ethylorthosilicate, dimethyltetraacetoxydisiloxane, oximosilane, acetoxysilane, acetoneoximesilane, enoxysilane and other trifunctional alkoxysilanes. and partial hydrolysis and condensation products thereof; bis(trialkoxysilylalkyl)amines, bis(dialkoxyalkylsilylalkyl)amines, bis(trialkoxysilylalkyl)N-alkylamines, bis(dialkoxyalkylsilylalkyl)N-alkylamines, bis(trialkoxysilylalkyl)ureas, bis(dialkoxyalkylsilylalkyl)ureas, bis(3-trimethoxysilylpropyl)amine, bis(3-triethoxysilylpropyl)amine, bis(4-trimethoxysilylbutyl)amine, bis(4-triethoxysilylbutyl)amine, bis(3-trimethoxysilylpropyl)N-methylamine, bis(3-triethoxysilylpropyl)N-methylamine, bis(4-trimethoxysilylbutyl)N-methylamine, bis(4-triethoxysilylbutyl)N-methylamine, bis(3-trimethoxysilylpropyl)urea, bis(3-triethoxysilylpropyl)urea,Bis(4-trimethoxysilylbutyl)urea, Bis(4-triethoxysilylbutyl)urea, Bis(3-dimethoxymethylsilylpropyl)amine, Bis(3-diethoxymethylsilylpropyl)amine, Bis(4-dimethoxymethylsilylbutyl)amine, Bis(4-diethoxymethylsilylbutyl)amine, Bis(3-dimethoxymethylsilylpropyl)N-methylamine, Bis(3-diethoxymethylsilylpropyl)N-methylamine, Bis(4-dimethoxymethylsilylbutyl) ethyl) N-methylamine, bis(4-diethoxymethylsilylbutyl) N-methylamine, bis(3-dimethoxymethylsilylpropyl)urea, bis(3-diethoxymethylsilylpropyl)urea, bis(4-dimethoxymethylsilylbutyl)urea, bis(4-diethoxymethylsilylbutyl)urea, bis(3-dimethoxyethylsilylpropyl)amine, bis(3-diethoxyethylsilylpropyl)amine, bis(4-dimethoxyethylsilylbutyl)amine, bis(4-diethoxymethylsilylbutyl)amine bis(3-dimethoxyethylsilylpropyl) N-methylamine, bis(3-diethoxyethylsilylpropyl) N-methylamine, bis(4-dimethoxyethylsilylbutyl) N-methylamine, bis(4-diethoxyethylsilylbutyl) N-methylamine, bis(3-dimethoxyethylsilylpropyl)urea, bis(3-diethoxyethylsilylpropyl)urea, bis(4-dimethoxyethylsilylbutyl)urea and / or bis(4-diethoxyethylsilylbutyl)urea; bis(triethoxysilylpropyl)amine, bis(trimethoxysilylpropyl)amine, bis(triethoxysilylpropyl)urea, bis(diethoxymethylsilylpropyl) N-methylamine; di- or trialkoxysilyl-terminated polydialkylsiloxanes, di- or trialkoxysilyl-terminated polyarylalkylsiloxanes, di- or trialkoxysilyl-terminated polypropylene oxide, polyurethanes,Examples of the crosslinking agent (ii) include polyacrylates, polyisobutylenes, di- or triacetoxysilyl-terminated polydialkyls, polyarylalkylsiloxanes, di- or trioxyiminosilyl-terminated polydialkyls, polyarylalkylsiloxanes, and di- or triacetoxy-terminated polydialkyls or polyarylalkyls. The crosslinking agent (ii) may also include any combination of two or more of the above.

[0025] The condensation catalyst (iii) used in the present invention is selected from the group of titanates and / or zirconates, which increases the rate at which the composition cures. By titanate or zirconate, we mean a titanium or zirconium atom having up to four organic groups (typically alkyl groups) or chelates attached through oxygen, i.e., M-OR, where M is titanium or zirconium. In most cases, R is an alkyl group or chelate containing up to 10 carbons, as discussed below.

[0026] The titanate-based catalyst and / or zirconate-based catalyst can be represented by the general formula Ti[OR 22 ]4 or Zr[OR 22 ]4[In the formula, each R 22 may be the same or different and represent a monovalent, primary, secondary, or tertiary aliphatic hydrocarbon radical, which may be linear or branched, having 1 to 10 carbon atoms. Optionally, the titanate and / or zirconate may contain partially unsaturated groups. R 22 Examples of R include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, tertiary butyl, and branched secondary alkyl groups such as 2,4-dimethyl-3-pentyl. 22 If are identical, R 22is an isopropyl group, a branched secondary alkyl group, or a tertiary alkyl group, particularly tertiary butyl. Examples of suitable titanates include tetra n-butyl titanate, tetra t-butyl titanate, titanium tetrabutoxide, and tetraisopropyl titanate. Examples of suitable zirconates include tetra n-propyl zirconate, tetra n-butyl zirconate, and zirconium diethyl citrate.

[0027] The titanate and / or zirconate may be chelated. Chelation may be by any suitable chelating agent, such as an alkyl acetylacetonate, e.g., methyl or ethyl acetylacetonate. Alternatively, the titanate may be a monoalkoxy titanate, resulting in a triple chelating agent, e.g., 2-propanolato, trisisooctadecanoato titanate, or diisopropyldiethylacetoacetate titanate.

[0028] The molar ratio of catalyst M-OR functional groups, where M is titanium or zirconium, to the sum of water and all silicon-bonded hydroxyl groups present in the filler present in the composition, as determined according to ISO 787-2:1981, is from 0.01:1 to 0.6:1. In one embodiment, R is R as defined above. 22 is.

[0029] Fillers (iv) used in the present invention include reinforcing fillers, non-reinforcing fillers, or combinations thereof.

[0030] Examples of finely divided reinforcing fillers include high surface area fumed and precipitated silicas such as rice husk ash, as well as some calcium carbonate. Examples of finely divided non-reinforcing fillers include crushed quartz, diatomaceous earth, barium sulfate, iron oxide, titanium dioxide, carbon black, glass beads, hollow glass beads, talc, and wollastonite. Other fillers that may be used alone or in combination with the above fillers include carbon nanotubes, e.g., multi-walled carbon nanotubes, carbon fiber, aluminite, calcium sulfate (anhydrite), gypsum, calcium sulfate, barium titanate, magnesium carbonate, kaolin, aluminum trihydroxide, clays such as magnesium hydroxide (hydrotalcite), graphite, diamond, copper carbonate (e.g., malachite), nickel carbonate (e.g., sallachite), barium carbonate (e.g., witherite), and / or strontium carbonate (e.g., strontium sieboldii). Examples of anhydrous inorganic fillers are exemplified by onyx; metal oxides such as aluminum trihydrate, aluminum oxide, beryllium oxide, magnesium oxide, zinc oxide, etc.; nitrides such as aluminum nitride and boron nitride; carbides such as silicon carbide and tungsten carbide, and combinations thereof.

[0031] Further examples of fillers (iv) include aluminum oxide, silicates from the group consisting of the olivine family, the garnet family, aluminosilicates, cyclic silicates, chain silicates, and layer silicates. The olivine family includes silicate minerals such as, but not limited to, forsterite and Mg2SiO4. The garnet family includes red garnet; Mg3Al2Si3O 12 ; green garnet; and Ca2Al2Si3O 12 The aluminosilicates include, but are not limited to, ground silicate minerals such as sillimanite; Al2SiO5; mullite; 3Al2O3.2SiO2; kyanite; and Al2SiO5. The cyclic silicate family includes, but is not limited to, cordierite and Al3(Mg,Fe)2[Si4AlO 18The chain silicate family includes, but is not limited to, crushed silicate minerals such as wollastonite and Ca[SiO3]. The layer silicates include, but are not limited to, mica; K2AI 14 [Si6Al2O 20 ](OH)4;phyllite;Al4[Si8O 20 ](OH)4; talc, Mg6[SiO 20 ](OH)4; serpentine, e.g. asbestos; kaolinite; Al4[Si4O 10 ](OH)8; and silicate minerals such as vermiculite.

[0032] Any combination of two or more of the above fillers (iv) may be used.

[0033] In a preferred embodiment, the filler (iv) used is selected from fumed and precipitated silica, calcium carbonate, carbon black, hollow glass beads and / or carbon nanotubes, such as multi-walled carbon nanotubes, and mixtures thereof.

[0034] Filler (iv) may optionally be surface-treated with a treating agent. Treating agents and treatment methods are known in the art. The surface treatment of fillers is typically carried out using, for example, fatty acid esters such as fatty acids or stearates, or organosilanes, organosiloxanes, or organosilazanes, such as hexaalkyldisilazanes or short-chain siloxanediols. Generally, the surface treatment makes the filler hydrophobic, thus facilitating handling and obtaining a homogeneous mixture with other components in the composition. Silanes, for example, R 7 e Si(OR 6 ) 4-e [In the formula, R 7is a substituted or unsubstituted monovalent hydrocarbon group having 6 to 20 carbon atoms, for example, alkyl groups such as hexyl, octyl, dodecyl, tetradecyl, hexadecyl, and octadecyl, and aralkyl groups such as benzyl and phenylethyl, with alkyl groups having 6 to 20 carbon atoms being preferred; R 6 is an alkyl having 1 to 6 carbon atoms and the letter e is 1, 2, or 3] can also be used as a filler treating agent.

[0035] The composition containing the above (i) to (iv) may preferably be: (i) a silanol-terminated polydimethylsiloxane having a viscosity of 30,000 mPa·s to 200,000 mPa·s at 23°C in an amount of 60% to 90% by weight of the composition, or alternatively 70% to 90% by weight of the composition; (ii) a crosslinker comprising a silyl-functional polymer having at least two silyl groups, each silyl group containing at least two hydrolyzable groups, in an amount of 1.0% to 10.0%, alternatively 1% to 7.5%, by weight of the composition; (iii) a condensation catalyst selected from the group of titanates and / or zirconates in an amount of 0.01% to 5.0%, alternatively 0.05% to 3.0% by weight of the composition; (iv) a filler in an amount of 10% to 40% by weight, alternatively 10% to 25% by weight, alternatively 10% to 20% by weight of the composition, where the total weight percent of the composition including (i) to (iv) is 100% by weight.

[0036] The hollow body (v) used in the present invention is a hollow, preferably spherical, body, and examples thereof include inorganic hollow bodies such as glass balloons, hollow silica, shirasu balloons, fly ash balloons, and ceramic balloons; and resin hollow bodies. Examples of resin hollow bodies include resin hollow bodies having an outer shell made of a phenolic resin, urea resin, polystyrene resin, polyvinylidene chloride, or acrylonitrile copolymer (e.g., a copolymer of acrylonitrile and methacrylonitrile, or a copolymer of acrylonitrile and a vinyl monomer copolymerizable with acrylonitrile, such as butadiene or styrene). Among these, resin hollow bodies are preferred from the viewpoints that the outer shell is less likely to crack, the hollow body maintains its shape, and the sound absorption properties are excellent.

[0037] The hollow body (v) used in the present invention has a true specific gravity of 0.3 or less and an average particle size of 20 μm to 200 μm. By satisfying these conditions, the sealant composition can be endowed with appropriate flowability and excellent sound absorption properties. The true specific gravity is preferably 0.1 or less, and more preferably 0.01 to 0.1. The average particle size is preferably 20 μm to 100 μm. The true specific gravity and average particle size can be measured by known methods. For example, the true specific gravity can be measured by the liquid displacement method, and the average particle size can be measured as the median diameter (D50: particle size at 50% of the cumulative particle size distribution) by laser diffraction.

[0038] The hollow body (v) is blended in an amount of 0.1 to 100 parts by mass, preferably 0.1 to 50 parts by mass, and more preferably 1 to 30 parts by mass, per 100 parts by mass of the silanol-terminated polydimethylsiloxane (i).

[0039] The sealant composition of the present invention comprises each of the ingredients (i) to (v) above. The sealant composition of the present invention is typically stored in multiple, usually two-component curable forms prior to use. In the case of two-component curable compositions, they may be mixed using any suitable standard two-part mixing device, such as a dynamic or static mixer, and, if desired, dispensed from the device for use in the intended application.

[0040] One embodiment of the two components is exemplified below: One part is Part A and the other part is Part B.

[0041] [Table 1]

[0042] In each case, the filler (iv) and the catalyst (iii) are not in the same part. Preferably, the filler (iv) is mixed with the polymer (i) in the base part, which may also contain other additives.

[0043] The two parts can be mixed in any suitable ratio (by mass) of base part to catalyst package, for example, 15:1 to 1:1, or 10:1 to 1:1, preferably 10:1 to 5:1.

[0044] In addition to the above components, optional components may be blended into the sealant material composition of the present invention, as long as the object of the present invention is achieved.

[0045] Examples of optional ingredients include adhesion promoters, heat resistance agents, cold resistance agents, flame retardants, thixotropic agents, pigments, surfactants, fluxes, acid acceptors, protectants, UV stabilizers, antioxidants, antiozonants, anti-corrosion additives, dyes, and any suitable combination thereof.

[0046] The sealant composition of the present invention preferably has a complex viscosity of 4000 Pa s or less at 30°C, for example, 7 days after mixing the liquids A and B. By having a complex viscosity of 4000 Pa s or less at 30°C, the sealant composition can easily flow into the formed through-holes, and can be further imparted with appropriate flowability that prevents the sealant composition from flowing toward the center of the tire tread in the width direction during tire running. The complex viscosity at 30°C is preferably from 500 to 4000 Pa·s, and more preferably from 1000 to 3000 Pa·s. The complex viscosity can be measured by the method described in ASTM D4440.

[0047] The sealant composition of the present invention is preferably such that, for example, 7 days after mixing the A and B liquids, a sample of the sealant composition having a thickness of 1.2 mm is placed on parallel plates having a diameter of 8 mm, and a shear stress of 3000 Pa is applied in the rotational direction of the parallel plates for 60 minutes, resulting in a deformation of the sample of 100% or less. The deformation amount of the sample is measured under the following conditions. Measurement equipment: TA Instruments ARES-G2 dynamic viscoelasticity measuring instrument Jig: 8mm diameter parallel plate Sample thickness: 1.2 mm Shear stress: 3000Pa Duration: 60 minutes

[0048] Hereinafter, the measurement of the deformation amount of the sample will be described with reference to FIG. The measuring device has, as its main components, a rotatable jig 1 and a jig 2 facing jig 1. Jigs 1 and 2 are equipped with parallel plates 12 and 14, respectively. First, a sample S made of the sealant material composition and having a thickness of 1.2 mm is placed on parallel plate 12 having a diameter of 8 mm, and sample S is fixed between parallel plate 12 and another parallel plate 14. The thickness of sample S is 1.2 mm. Only parallel plate 12 is rotated, and a shear stress of 3000 Pa is applied in the direction of rotation for 60 minutes, and the deformation (strain) of sample S after 60 minutes is measured. The temperature in the measurement chamber is set to 80°C.

[0049] In the present invention, the deformation amount is more preferably 10 to 100%. The sealant material composition of the present invention having the above-described deformation amount can more easily flow into the formed through-holes and can further impart appropriate flowability so that the composition does not flow toward the center in the width direction of the tire tread when the tire is running.

[0050] The sealant composition of the present invention can be applied as a sealant layer on the radially inner side of the inner liner layer in the tread of a pneumatic tire. The sealant layer can be formed by applying the sealant composition of the present invention in the form of a string or strip using a nozzle, with the liquids A and B being mixed together before application from the nozzle. When a foreign object such as a nail penetrates the tread, the sealant constituting the sealant layer flows into the hole, thereby preventing a decrease in air pressure and enabling the tire to continue running. The sealant layer preferably has a thickness of 2 mm to 6 mm. [Example]

[0051] The present invention will be further described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, "parts" means "parts by mass."

[0052] Standard Example, Examples 1 to 5 and Comparative Example 1 Liquid A and liquid B were prepared in the formulations (parts by mass) shown in Table 1 to obtain sealant compositions.

[0053] Test tire production A pneumatic tire having a tire size of 255 / 45R19, a tread portion, a pair of sidewall portions, and a pair of bead portions, and having a sealant layer made of a sealant material on the radially inner side of the inner liner layer in the tread portion, was coated with the various sealant materials described above as the sealant layer to produce various test tires. The application was carried out using a nozzle and an application device that mixed the A and B solutions upstream of the nozzle at a mass ratio of 10:1. The sealant layer was 3 mm thick.

[0054] Sealing performance evaluation The test tire was mounted on an SUV (2400cc class vehicle), the air pressure was set to 230kPa, and the load was set to 100% of the maximum load. A φ4mm nail was pierced into the shoulder of the test tire, and after removing the nail and leaving it for one hour, the air pressure of the test tire was measured and evaluated according to the following criteria. A rating of ◯ or △ was sufficient for practical use. 〇: 200kPa or more △: 150kPa or more and less than 200kPa ×: Less than 150 kPa

[0055] Flowability evaluation The test tire was mounted on an SUV (2400cc class vehicle), the air pressure was set to 230 kPa, and the vehicle was driven at 200 km / h for 1 hour. After that, the degree of flow from the edge of the sealant layer of the test tire was checked and evaluated according to the following evaluation criteria. ◎: Within 0.5cm 〇: 0.5 to less than 1 cm △: 1cm or more but less than 2cm ×: 2cm or more

[0056] Sound absorption evaluation The test tire was mounted on an SUV (2400cc class vehicle), and the air pressure was set to 230kPa, with a load of 100% of the maximum load, and sound absorption was evaluated. Sound absorption was evaluated by the driver's sensory evaluation. The results were expressed as an index, with the standard example value being 100. The higher the index, the better the sound absorption.

[0057] The complex viscosity and deformation of the sealant were also measured by the methods described above.

[0058] The results are shown in Table 2.

[0059] [Table 2]

[0060] *1:Silanol-terminated polydimethylsiloxane (having a number-average molecular weight of approximately 60,000 g / mol and a viscosity of approximately 50,000 mPa·s at 23°C) *2: Trimethoxysilyl-terminated polydimethylsiloxane (crosslinking agent) (having a number-average molecular weight of approximately 63,000 g / mol and a viscosity of 56,000 mPa·s at 23°C) *3: Carbon black (Evonik Printex A) *4: Hollow body 1 (F-65DE manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., acrylonitrile polymer, average particle size 40 to 60 μm, true specific gravity 0.030 ± 0.005) *5: Hollow body 2 (F-80DE manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., acrylonitrile polymer, average particle size 90-130 μm, true specific gravity 0.020 ± 0.005) *6: Hollow body 3 (MFL-100MCA manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., acrylonitrile polymer / calcium carbonate, average particle size 60-70 μm, true specific gravity 0.12 ± 0.02) *7:Tetra n-butoxy titanium

[0061] From the results in Table 1, it can be seen that the sealant material composition of each example contains (i) at least one silanol-terminated polydimethylsiloxane having at least two hydroxyl functional groups per molecule, (ii) silanes having at least two hydrolyzable groups or at least three hydrolyzable groups per molecule, and silyl-functional molecules having at least two silyl groups, each silyl group containing at least two hydrolyzable groups or at least three hydrolyzable groups; and at least one cross-linking agent selected from the group (iii) a condensation catalyst selected from the group of titanates and / or zirconates; (iv) a filler; and (v) a hollow body having a true specific gravity of 0.3 or less and an average particle size of 20 μm to 200 μm; Including, The sealant material composition is a two-component curing type in which the (iii) and the (iv) are not stored together before use, It was found that the blending amount of the hollow bodies with respect to 100 parts by mass of the (i) silanol-terminated polydimethylsiloxane was 0.1 to 100 parts by mass, and therefore the sealing property and flowability were good, and the sound absorption properties were also excellent. In contrast to this, in Comparative Example 1, the blending amount of hollow bodies (v) exceeded the upper limit specified by the present invention, and therefore the sealing property deteriorated.

[0062] The present invention includes the following embodiments. Embodiment 1: A sealant material composition constituting a sealant layer of a pneumatic tire having a sealant layer on the inner surface of the tire, comprising: (i) at least one silanol-terminated polydimethylsiloxane having at least two hydroxyl functional groups per molecule; (ii) silanes having at least two hydrolyzable groups or at least three hydrolyzable groups per molecule, and silyl-functional molecules having at least two silyl groups, each silyl group containing at least two hydrolyzable groups or at least three hydrolyzable groups; and at least one cross-linking agent selected from the group (iii) a condensation catalyst selected from the group of titanates and / or zirconates; (iv) a filler; and (v) a hollow body having a true specific gravity of 0.3 or less and an average particle size of 20 μm to 200 μm; Including, The sealant material composition is a two-component curing type in which the (iii) and the (iv) are not stored together before use, The blending amount of the hollow bodies is 0.1 to 100 parts by mass per 100 parts by mass of the (i) silanol-terminated polydimethylsiloxane. A sealant material composition characterized by: Embodiment 2: The sealant material composition according to embodiment 1, wherein the hollow body (v) has a true specific gravity of 0.1 or less. Embodiment 3: The sealant material composition according to embodiment 1 or 2, wherein the hollow body (v) is at least one selected from glass balloons, hollow resin bodies, hollow silica, shirasu balloons, fly ash balloons, and ceramic balloons. Embodiment 4: 4. The sealant material composition according to any one of embodiments 1 to 3, wherein the complex viscosity of the sealant material composition at 30°C after mixing the two components is 4000 Pa·s or less. Embodiment 5: 5. The sealant material composition according to any one of embodiments 1 to 4, wherein, after mixing the two components, a sample of the sealant material composition having a thickness of 1.2 mm is placed on parallel plates having a diameter of 8 mm, and a shear stress of 3000 Pa is applied in the rotational direction of the parallel plates for 60 minutes, and the sample deforms by 100% or less. Embodiment 6: A tire using the sealant material composition according to any one of embodiments 1 to 5. Embodiment 7: 7. The tire according to embodiment 6, wherein the sealant material composition has a thickness of 2 to 6 mm. [Explanation of symbols]

[0063] 1, 2 Jig 12, 14 Parallel Plate

Claims

1. A sealant material composition constituting a sealant layer of a pneumatic tire having a sealant layer on the inner surface of the tire, comprising: (i) at least one silanol-terminated polydimethylsiloxane having at least two hydroxyl functional groups per molecule; (ii) a silane having at least two hydrolyzable groups or at least three hydrolyzable groups per molecule, and a silyl-functional molecule having at least two silyl groups, each silyl group containing at least two hydrolyzable groups or at least three hydrolyzable groups; and at least one cross-linking agent selected from the group (iii) a condensation catalyst selected from the group of titanates and / or zirconates; (iv) a filler; and (v) a hollow body having a true specific gravity of 0.3 or less and an average particle size of 20 μm to 200 μm; Including, The sealant material composition is a two-component curing type in which the (iii) and the (iv) are not stored together before use, The blending amount of the hollow bodies is 0.1 to 100 parts by mass per 100 parts by mass of the (i) silanol-terminated polydimethylsiloxane. A sealant material composition characterized by:

2. 2. The sealant material composition according to claim 1, wherein the hollow body (v) has a true specific gravity of 0.1 or less.

3. 2. The sealant material composition according to claim 1, wherein the hollow bodies (v) are at least one selected from the group consisting of glass balloons, hollow resin bodies, hollow silica, shirasu balloons, fly ash balloons, and ceramic balloons.

4. 2. The sealant material composition according to claim 1, wherein the complex viscosity of the sealant material composition at 30°C after mixing the two components is 4000 Pa·s or less.

5. 2. The sealant material composition according to claim 1, wherein a sample of the sealant material composition having a thickness of 1.2 mm is placed on parallel plates having a diameter of 8 mm, and a shear stress of 3000 Pa is applied in the rotational direction of the parallel plates for 60 minutes. The sealant material composition according to claim 1, wherein the sample deforms by 100% or less after mixing the two components.

6. A tire using the sealant material composition according to claim 1.

7. 7. The tire according to claim 6, wherein the thickness of the sealant material composition is 2 to 6 mm.

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