KR101806907B1 - Composition For Tire Innerliner and Tire Manufactured By Using The Same - Google Patents

Abstract

The present invention relates to a rubber composition for tire inner liner and a tire manufactured by using the same. The rubber composition for tire inner liner uses silicone rubber as raw material rubber and comprises 20 to 50 parts by weight of carbon black with respect to 100 parts by weight of the silicone rubber, thereby reducing the thickness and showing excellent resistance to air permeability when compared to existing compositions.

Description

Technical Field [0001] The present invention relates to a rubber composition for an inner liner and a pneumatic tire using the rubber composition.

The present invention relates to a rubber composition for a tire inner liner capable of exhibiting excellent air permeability while reducing the thickness of the inner liner, and a tire produced using the same.

The inner liner of the tire is located in the innermost part of the tire, and it serves to maintain the air pressure inside the tire without air leaking. Accordingly, the air permeability of the rubber composition for a tire innerliner is required, and in particular, the low air permeability not only improves the running stability by keeping the air pressure of the tire constant, but also reduces the rolling resistance of the tire, Which is one of the most important physical properties of the inner liner.

In order to lower the air permeability, a number of butyl rubber or halogenated butyl rubber having low air permeability have been disclosed as a main component. However, in order to obtain sufficient air tightness, the rubber content or the inner liner thickness is increased . As a result, the total weight of the tire is increased and the fuel efficiency of the automobile is lowered, air pockets are formed between the inner rubber of the carcass layer and the inner liner in the process of vulcanizing the tire or running the vehicle, The shape and physical properties of the inner liner also changed.

Japanese Patent Publication No. 47-31761 discloses that a solution or dispersion of a synthetic resin such as polyvinylidene chloride, saturated polyester resin, or polyamide resin is applied to the inner surface of a vulcanized tire at a thickness of 0.1 mm or less . However, the above-described technique has a problem in that the adhesion between the rubber and the synthetic resin is problematic and the moisture resistance of the inner liner layer deteriorates.

Further, Japanese Patent Application Laid-Open No. 5-508435 discloses a tire comprising a halogen-containing copolymer of a C4 to C7 isomonoolefin and a p-alkylstyrene as a constituent of a tire inner liner, which contains a plasticizer, a carbon black and a vulcanizing agent It has been proposed to use the composition as a tire inner liner. However, such an inner liner has a problem that the air permeability coefficient is insufficient and is not suitable for reducing the weight of the tire.

It is an object of the present invention to provide a rubber composition for a tire innerliner which improves the adhesion of halobutyl rubber and improves the fuel efficiency due to an increase in thickness and is excellent in air permeability, endurance and heat aging resistance.

Another object of the present invention is to provide a tire produced by using the tire innerliner rubber composition.

In order to achieve the above object, the rubber composition for a tire inner liner according to an embodiment of the present invention comprises 30 to 50 parts by weight of carbon black relative to 100 parts by weight of silicone rubber.

A tire according to another embodiment of the present invention is manufactured using the rubber composition for a tire innerliner.

The rubber composition for a tire innerliner according to the present invention exhibits excellent air permeability and fatigue resistance without decreasing tensile strength even if the inner liner thickness is reduced. As a result, it can contribute to weight reduction of a tire and improvement of automobile fuel economy.

The rubber composition for an inner liner of the present invention may contain 30 to 50 parts by weight of carbon black relative to 100 parts by weight of the silicone rubber.

The silicone rubber is a rubber elastomer which is crosslinked by mixing a high-molecular-weight straight-chain diorganopolysiloxane with fine silica or the like as a reinforcing agent, and is excellent in weatherability and electrical properties, and can be used in a range of -50 to 200 ° C. Even at -45 ℃, rubber elasticity is not lost. Even if left at 250 ℃ for 3 days, change of strength and elongation can be kept within 10%.

When butyl rubber or halobutyl rubber is used as the starting rubber, there is a problem that the thickness is thick considering the air permeability and the cord exposures of the body ply. When silicone rubber is used as raw material rubber, it has excellent air permeability because there is no double bond in the same thickness as butyl rubber or halobutyl rubber.

In the past, a small amount of silicone rubber was used as a filler (filler) while using raw rubber to apply the heat resistance of the silicone to a tire. However, the present inventors have made efforts to improve the air permeability and reduce the thickness of the inner liner, The present inventors have completed the present invention by using silicone rubber as rubber and finding the most preferable amount of carbon black to be added.

In order to use the raw rubber as the silicone rubber instead of the butyl rubber or the halobutyl rubber, the content of the carbon black is preferably 30 to 50 parts by weight.

When the content of the carbon black is less than 30 parts by weight, the tensile strength may be lowered. When the content of the carbon black is more than 50 parts by weight, the flexural fatigue performance may be deteriorated.

The CTAB specific surface area of carbon black is preferably 20 m ² / g to 55 m ² / g, more preferably 20 m ² / g to 40 m ² / g, and most preferably 40 m ² / g.

When the CTAB specific surface area of the carbon black is less than 20 m ² / g, there is a problem with the reinforcing property. When the specific surface area exceeds 55 m ² / g, there is a problem in dispersion.

The vulcanizing agent is preferably a peroxide such as benzoyldicumyl peroxide. Silicone rubber has little double bonds.

<Rubber component>

 In the rubber composition for an inner liner of the present invention, the silicone rubber can be used without limiting the manufacturer or the like.

<Carbon black>

The carbon black may be included in an amount of 30 to 50 parts by weight based on 100 parts by weight of the silicone rubber. When the content of the carbon black is less than 30 parts by weight, the tensile strength may be lowered. When the content of the carbon black is more than 50 parts by weight, the flexural fatigue performance may be deteriorated.

The carbon black has a CTAB specific surface area of 20 to 40 m ² / g, and ASTM standards N500 to N700 can be used.

&Lt; Other compounding agent >

In the rubber composition for an inner liner of the present invention, it is preferable to use an organic peroxide as the vulcanizing agent.

The organic peroxide can be, for example, benzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide, 2,5- Di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 2,5- Di-t-butylperoxybenzene, t-butylperoxybenzene, 2,4-dichlorobenzoylperoxide, 1,1-di (tert-butylperoxy) t-butylperoxy-3,3,5-trimethylsiloxane, n-butyl-4,4-di-t-butylperoxyvalerate, and the like. Of these, benzoyl peroxide, dicumyl peroxide, t-butyl peroxybenzene and di-t-butyl peroxy-diisopropylbenzene are preferable, and benzoyl peroxide can be more preferably used.

The vulcanizing agent may be used alone or in combination of two or more kinds.

The vulcanization accelerator may be at least one selected from the group consisting of a sulfenamide system, a thiazole system, a thiuram system, a thiourea system, a guanidine system, a dithiocarbamate system, an aldehyde-amine system or an aldehyde-ammonia system, May be used.

Examples of the sulfenamide system include CBS (N-cyclohexyl-2-benzothiazylsulfenamide), TBBS (N-tert-butyl-2-benzothiazylsulfenamide), N, N-dicyclohexyl- Sulfinamide compounds such as thiazyl sulfenamide, N-oxydiethylene-2-benzothiazyl sulfenamide and N, N-diisopropyl-2-benzothiazole sulfenamide.

Examples of the thiazole system include sodium salts, zinc salts, copper salts, cyclohexylamine salts, 2- ((2-mercaptobenzothiazole), 2-mercaptobenzothiazole Thiazole-based compounds such as 2,4-dinitrophenyl) mercaptobenzothiazole and 2- (2,6-diethyl-4-morpholinothio) benzothiazole can be used.

Examples of the thiuram compound include TMTD (tetramethylthiuram disulfide), tetraethylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram disulfide, dipentamethylenethiuram monosulfide, dipentamethylthiuram tetrasulfide , Dipentamethylenethiuram hexa sulphide, tetrabutyl thiuram disulfide, and pentamethylenethiuram tetrasulfide can be used.

Examples of the thiourea compound include thiourea compounds such as thiacarbamide, diethyl thiourea, dibutyl thiourea, trimethyl thiourea, and diorthotolyl thiourea.

As the guanidine-based compound, guanidine-based compounds such as diphenylguanidine, diorthotolylguanidine, triphenylguanidine, orthotolylbiguanide, and diphenylguanidine phthalate can be used.

Examples of dithiocarbamates include zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate , Zinc dibutyldithiocarbamate, zinc diamidithiocarbamate, zinc dipropyldithiocarbamate, complexing of zinc with piperidinediocarbamate and piperidine, hexadecyl (or octadecyl ) Zinc isopropyl dithiocarbamate, zinc dibenzyldithiocarbamate, sodium diethyldithiocarbamate, piperidine pentamethylene dithiocarbamate, selenium dimethyldithiocarbamate, diethyl And dithiocarbamate-based compounds such as tellurium dithiocarbamate and cadmium diamidithiocarbamate.

Examples of the aldehyde-amine type or aldehyde-ammonia type include aldehyde-amine type or aldehyde-ammonia type compounds such as acetaldehyde-aniline reactant, butylaldehyde-aniline condensate, hexamethylenetetramine and acetaldehyde- .

As the imidazoline compound, for example, imidazoline compounds such as 2-mercaptoimidazoline and the like can be used. As the xanthate-based compound, for example, a xanthate-based compound such as zinc dibutylxanthogenate can be used. These vulcanization accelerators may be used alone or in combination of two or more.

As the vulcanization accelerating auxiliary, for example, zinc oxide, stearic acid and the like can be used.

Oils may be exemplified by process oils, plant oils, or mixtures thereof. As the process oil, paraffinic process oil, naphthenic process oil, aromatic process oil and the like can be mentioned. The vegetable oils include vegetable oils such as castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, pine oil, pine tar, tall oil, Milk, milk, yam, macadamia nut oil, safflower oil, tung oil and the like.

The pneumatic tire of the present invention is produced by a conventionally known method using the rubber composition for inner liner of the present invention. That is, the rubber composition for an inner liner containing the above-described essential components and other compounding agents as required is kneaded and extruded in accordance with the shape of the rubber for inner liner of the tire at the stage of unvulcanization, And an unvulcanized tire is formed on the tire molding machine by molding in a usual manner. By heating and pressing the unvulcanized tire in a vulcanizer, the pneumatic tire of the present invention can be obtained.

&Lt; Examples 1 to 5 >

The composition as shown in Table 1 below except for the sulfur and vulcanization accelerator was added to a Banbury mixer and kneaded at about 150 ° C for 3 minutes. Subsequently, sulfur and a vulcanization accelerator were added to the obtained kneaded product in the amounts shown in Table 1 and kneaded at about 80 DEG C for 5 minutes using a biaxial open roll to obtain an unvulcanized rubber composition Lt; / RTI &gt;

The unvulcanized rubber composition thus obtained was extruded to a predetermined thickness to prepare an unvulcanized rubber sheet, which was then vulcanized at 170 DEG C for 10 minutes to obtain a vulcanized rubber sheet.

On the other hand, the unvulcanized rubber composition obtained above was extruded in a sidewall shape, molded in combination with another member, vulcanized at a temperature of 150 DEG C and a pressure of 25 kgf for 35 minutes with a tire molding machine, 65R15).

<Experimental Example 1: Measurement of physical properties of the rubber composition>

(Durometer A hardness)

The vulcanized rubber sheet obtained by the above method was measured for durometer A hardness at room temperature in accordance with JIS K6253.

(Tensile strength TB, elongation at break EB, 300% modulus)

The tensile strength TB (MPa) and the elongation at break (%) of EB were measured at room temperature in accordance with JIS K6251 for a No. 3 dumbbell specimen cut out from the vulcanized rubber sheet obtained by the above method.

(De Mattia curvature test)

The specimens having a length of 140 mm to 155 mm and a width of 25 mm 0.1 mm cut out from the vulcanized rubber sheet obtained by the above method were subjected to a dynamical bending test machine to change the strain by the method according to JIS K6260, The growth rate was measured. The measurement results are expressed as the number of bends until the crack grows to 1 mm. The larger the value, the better the bending thermal growth resistance.

(Cold Storage Crack Test)

Test specimens of 140 to 150 mm in length and 20 to 0.1 mm in width, cut out from the vulcanized rubber sheet obtained by the above method, are placed in a -40 ° chamber to check for the occurrence of cracks.

<Experimental Example 2: Measurement of physical properties of manufactured tire>

(Air permeability)

The tire inner liner film was used to produce a green tire of 195/65 R15, followed by vulcanization to prepare a final tire. The air permeability of the test tire produced by the above method was evaluated. The lower the value, the higher the permeability of air.

(Tire appearance evaluation)

If there is no damaged portion of the inner liner portion after vulcanization, it is evaluated as good, and if there is a damaged portion, it is evaluated as bad.

Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 combination
(Parts by mass) Halogenated butyl rubber 100 50 - - - - - - Silicone rubber ^{1 )} - 50 100 100 100 100 100 100 Carbon black ^{2 )} 50 50 10 20 30 40 50 70 Vulcanizing agent (sulfur) ^{3 )} 1.5 1.0 0 0 0 0 0 0 Vulcanizing agent (organic peroxide) ^{4 )} - 0.8 1.2 1.2 1.2 1.2 1.2 1.2 Stearic acid 2 One 0 0 0 0 0 0 Zinc oxide 1.5 1.5 0 0 0 0 0 0 Vulcanization accelerator 1.5 1.0 0.2 0.2 0.2 0.2 0.2 0.2 evaluation Durometer A Hardness 50 49 42 43 48 48 50 53 300% modulus (kg / cm2) 82 70 58 53 72 75 77 93 Break elongation EB (%) 532 580 624 601 580 530 632 670 Dimatia test (1 mm growth) 40,000 40,000 55,000 55,000 55,000 55,000 45,000 30,000 Low Temperature Storage Crack Yes / No (-40 ℃) radish radish radish radish radish radish radish U Air permeability (inner liner thickness: 2 mm) 198 176 153 148 143 145 148 151 Tire Appearance Good Good Good Good Good Good Good Good

(Unit: parts by weight)

1) Silicone rubber: organic silicon, KCC

2) Carbon black: CTAB specific surface area (40 m ² / g)

3) Vulcanizing agent: sulfur, Miwon Corporation

4) Vulcanizing agents: organic peroxides: Peroxan HX, INFOCOMS

As shown in Table 1, when Comparative Example 1 in which carbon black was added in the same amount and Example 5 were compared, Example 5 in which silicone rubber was used in place of halogenated butyl rubber was evaluated to be excellent in air permeability and dimathia .

However, when the carbon black is 10 or 20 parts by weight (Examples 1 and 2), the hardness and the modulus are too low to be appropriate, and when 70 parts by weight, .

When the inner liner thickness is reduced when the silicone rubber is applied, the silicone rubber can have the same permeability as that of Comparative Example 1, thereby being useful for reducing the weight of the tire.

Claims (4)

A raw rubber and carbon black,
Wherein the raw material rubber includes a silicone rubber but not a butyl rubber and a halobutyl rubber,
Wherein the carbon black comprises 30 to 50 parts by weight based on 100 parts by weight of the raw rubber. delete The rubber composition for a tire innerliner according to claim 1, wherein the carbon black has a CTAB value of 20 to 55 m ² / g. A tire produced by using the rubber composition for a tire innerliner according to claim 1.