KR20210061201A - Dopamine functionalized carbon powder and rubber composition for tire inner liner comprising the same - Google Patents

Abstract

Provided are dopamine-modified carbon powder, a rubber composition for a tire inner liner including the same, and a tire manufactured from the rubber composition for an inner liner. The present invention provides an improved adhesion capability.

Description

Dopamine functionalized carbon powder and rubber composition for tire inner liner comprising the same}

It relates to a dopamine-modified carbon powder, and a rubber composition for a tire inner liner comprising the same.

The tire inner liner is a rubber layer formed inside the tire and plays an important role in maintaining the tire pressure and durability. In general, rubber for inner liner is mainly used for rubber with a low air permeation rate.

The inner liner is manufactured in a semi-finished form through processes such as mixing and extrusion, and then the rubber sheet is rewound during the tire molding process and cut to the required length according to the size of the tire, and the inner liner is attached to the inside by being wound on a forming drum. It is molded into green tires.

The rubber composition for an inner liner is a rubber that is applied to a portion of the tire in contact with the injected air, and its main required characteristics include excellent air permeability, high carcass adhesion, fatigue resistance, and the like.

As a conventional technology, the main required performance is improved by applying a halogenated (Br, Cl) butyl rubber having excellent air permeability, a gas barrier filler, and the like.

However, if the content of halogenated butyl rubber in the rubber composition increases, there is a problem in the manufacturing process due to a decrease in the workability of the compounded rubber and adhesion with the carcass due to a decrease in compatibility between rubbers. Fatigue life may decrease due to defects and dispersion defects.

One aspect is to provide a carbon powder with improved adhesion ability.

Another aspect is to provide a rubber composition comprising the carbon powder.

Another aspect is to provide a tire made of the rubber composition.

According to one aspect,

Dopamine-modified carbon powder is provided.

According to the other side,

There is provided a rubber composition for a tire inner liner comprising the dopamine-modified carbon powder.

According to another aspect,

There is provided a tire made of the rubber composition for the tire inner liner.

The rubber composition for an inner liner comprising a dopamine-modified carbon powder according to an embodiment of the present invention improves adhesion to the carcass layer and increases air permeability.

1 is a view schematically showing the structure of a tire according to an embodiment.
2 is a diagram schematically showing that graphene oxide is modified by dopamine.

Hereinafter, a carbon powder according to an exemplary embodiment, a rubber composition for a tire inner liner including the same, and a tire including the same will be described in more detail.

Since the inventive idea disclosed in the present specification can apply various transformations and have various implementations, specific implementations are described in detail in the detailed description, and when necessary, specific implementations are illustrated in the drawings. Effects and features of the creative ideas of the present specification, and a method of achieving them will be apparent with reference to implementation examples described later in detail together with the drawings. However, the creative idea of the present specification is not limited to the embodiments disclosed below, but may be implemented in various forms.

In the following embodiments, terms such as first and second are not used in a limiting meaning, but are used for the purpose of distinguishing one component from another component.

In the following embodiments, expressions in the singular include plural expressions unless the context clearly indicates otherwise.

In the following embodiments, terms such as include or have means that the features or elements described in the specification are present, and do not preclude the possibility of adding one or more other features or elements in advance.

When one embodiment can be implemented differently, a specific process order may be performed differently from the described order. For example, two processes described in succession may be performed substantially simultaneously, or may be performed in an order opposite to the described order.

Hereinafter, if necessary, embodiments of the present invention will be described in detail with reference to the accompanying drawings, and when describing with reference to the drawings, identical or corresponding components are given the same reference numerals, and redundant descriptions thereof will be omitted. It should be.

In the drawings, components may be exaggerated or reduced in size for convenience of description. For example, the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, and thus the creative ideas disclosed in the present specification are not necessarily limited to those shown.

The carbon powder according to an embodiment is a carbon powder modified with dopamine.

The term carbon powder means a powder consisting of substantially only carbon. The surface of the individual particles constituting the carbon powder may have CH or other common groups, but the inside of the particles is composed of a double bond of carbon, so it can be said that it is substantially composed of only carbon.

According to one embodiment of the present invention, the carbon powder may include carbon black, fullerene, CNT, graphene oxide, graphene, or any combination thereof. For example, the dopamine-modified carbon powder may be dopamine-modified graphene.

According to one embodiment of the present invention, the dopamine-modified carbon powder may be obtained by adding dopamine and carbon powder in a solvent and reacting at a temperature of 50 to 140° C. for 1 to 72 hours.

According to one embodiment of the present invention, the solvent may be water or polyol.

According to an embodiment of the present invention, the polyol is ethylene glycol (Ethylene Glycol), diethylene glycol (Diethylene Glycol), triethylene glycol (Triethylene Glycol), tetraethylene glycol (Tetraethylene Glycol, or any combination thereof. It may include.

According to an embodiment of the present invention, the reaction may be performed by spontaneous oxidation of dopamine under weakly basic conditions. Dopamine self-polymerization hardly reacts in acidic conditions, and reaction occurs in neutral conditions, but there are disadvantages of modification of dopamine and too thin coating thickness on carbon powder.

According to an embodiment of the present invention, the reaction may be carried out at a pH of 7.7 to 11.

According to an embodiment of the present invention, the weight ratio of the dopamine and the carbon powder may be 1:99 to 99:1. For example, the weight ratio of the dopamine and the carbon powder may be 1:3 to 3:1.

2 is a diagram schematically showing that the graphene oxide is modified by dopamine.

Referring to FIG. 2, it can be seen that the graphene oxide before modification has a dark yellow color.

When graphene (oxide) and dopamine are added to a solvent and heated, dopamine-modified graphene is obtained. Referring to FIG. 2, it can be seen that the modified graphene has a black color. It is believed that dopamine is partially polymerized during the modification process and is present on the graphene surface.

For example, dopamine-modified graphene is obtained by reacting for 10 to 36 hours at a temperature of 50 to 120°C and pH 8.0 to 10 by using water as a solvent and adding graphene (oxide) and dopamine. I can.

The rubber composition for a tire inner liner according to another embodiment includes the dopamine-modified carbon powder.

According to one embodiment of the present invention, the rubber composition may include 60 to 90 parts by weight of butyl rubber and 10 to 30 parts by weight of natural rubber as 100 parts by weight of raw rubber.

The butyl rubber may be, for example, a halogenated butyl rubber.

The natural rubber may be a general natural rubber or a modified natural rubber.

The general natural rubber may be used as long as it is known as natural rubber, and the country of origin is not limited. The natural rubber mainly contains cis-1,4-polyisoprene, but may contain trans-1,4-polyisoprene depending on required properties. Therefore, in addition to natural rubber containing cis-1,4-polyisoprene as a main body, the natural rubber includes trans-1,4-isoprene as a main body, such as Valata, a kind of rubber of the Sapota family from South America. It may also contain rubber.

The modified natural rubber means that the general natural rubber is modified or purified. For example, examples of the modified natural rubber include epoxidized natural rubber (ENR), deproteinized natural rubber (DPNR), and hydrogenated natural rubber.

According to one embodiment of the present invention, the rubber composition may include 1 to 5 parts by weight of the dopamine-modified carbon powder based on 100 parts by weight of the raw rubber.

When the amount of the dopamine-modified carbon powder is less than 1 part by weight, the effect of improving air permeability hardly appears, and when it exceeds 5 parts by weight, the air permeability may be lowered.

According to one embodiment of the present invention, the rubber composition may include a filler, for example, may include carbon black.

The carbon black may have a nitrogen adsorption specific surface area (nitrogen surface area per gram, N ₂ SA) of 30 to 300 m ² /g, and an oil absorption of DBP (n-dibutyl phthalate) of 60 to 180 cc/100 g, but the present invention This is not limited to this.

When the nitrogen adsorption specific surface area of the carbon black ^{exceeds 300 m 2} /g, the processability of the rubber composition for tires may be disadvantageous, and ^{when it is less than 30 m 2} /g, the reinforcing performance by carbon black as a filler may be disadvantageous. In addition, when the DBP oil absorption amount of the carbon black exceeds 180cc/100g, the processability of the rubber composition may be deteriorated, and when it is less than 60cc/100g, the reinforcing performance by carbon black as a filler may be disadvantageous.

Representative examples of the carbon black include N110, N121, N134, N220, N231, N234, N242, N293, N299, S315, N326, N330, N332, N339, N343, N347, N351, N358, N375, N539, N550, N582 , N630, N642, N650, N660, N683, N754, N762, N765, N774, N787, N907, N908, N990 or N991.

For example, the carbon black of the rubber composition for the inner liner may be N660.

The carbon black may be included in an amount of 50 to 90 parts by weight, for example, based on 100 parts by weight of the raw rubber, and is preferably included in an amount of 60 to 80 parts by weight.

According to one embodiment of the present invention, the rubber composition may further include a silicate as a filler. The silicate may be included in an amount of, for example, 10 to 50 parts by weight, and is preferably included in an amount of 20 to 40 parts by weight, based on 100 parts by weight of the raw rubber. For example, the silicate may be magnesium silicate.

The rubber composition for the tire inner liner may optionally further include various additives such as an additional vulcanizing agent, a vulcanization accelerator, a vulcanization accelerator, an anti-aging agent, an antioxidant, or a softening agent. Any of the various additives may be used as long as they are commonly used in the field to which the present invention belongs, and their content is not particularly limited as a bar depending on the blending ratio used in a conventional rubber composition for a tire inner liner.

As the vulcanizing agent, a sulfur-based vulcanizing agent can be preferably used. The sulfur-based vulcanizing agents include inorganic vulcanizing agents such as powdered sulfur (S), insoluble sulfur (S), precipitated sulfur (S), and colloidal sulfur, and tetramethylthiuram disulfide (TMTD), tetraethyl Organic vulcanizing agents such as tetraethyltriuram disulfide (TETD) and dithiodimorpholine may be used. As the sulfur vulcanizing agent, specifically elemental sulfur or a vulcanizing agent that produces sulfur, for example, amine disulfide, polymer sulfur, or the like may be used.

It is preferable that the vulcanizing agent be included in an amount of 0.5 to 10.0 parts by weight based on 100 parts by weight of the raw material rubber as an appropriate vulcanizing effect, and it is preferable in that the raw material rubber is less sensitive to heat and makes it chemically stable.

The vulcanization accelerator refers to an accelerator that accelerates the vulcanization rate or accelerates the delaying action in the initial vulcanization step.

The vulcanization accelerators include sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamic acid-based, aldehyde-amine-based, aldehyde-ammonia-based, imidazoline-based, xanthate-based and these Any one selected from the group consisting of combinations may be used.

Examples of the sulfenamide-based vulcanization accelerator include N-cyclohexyl-2-benzothiazylsulfenamide (CBS), N-tert-butyl-2-benzothiazylsulfenamide (TBBS), and N,N-dicyclohexyl Any one selected from the group consisting of -2-benzothiazylsulfenamide, N-oxydiethylene-2-benzothiazylsulfenamide, N,N-diisopropyl-2-benzothiazolesulfenamide, and combinations thereof Sulfenamide-based compounds of can be used.

Examples of the thiazole-based vulcanization accelerator include 2-mercaptobenzothiazole (MBT), dibenzothiazyl disulfide (MBTS), sodium salt of 2-mercaptobenzothiazole, and zinc salt of 2-mercaptobenzothiazole. , Copper salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, 2-(2,4-dinitrophenyl)mercaptobenzothiazole, 2-(2,6-di Any one thiazole-based compound selected from the group consisting of ethyl 4-morpholinothio)benzothiazole and combinations thereof may be used.

Examples of the thiuram-based vulcanization accelerator include tetramethyl thiuram disulfide (TMTD), tetraethyl thiuram disulfide, tetramethyl thiuram monosulfide, dipentamethylene thiuram disulfide, dipentamethylene thiuram monosulfide, dipentamethylene Thiuram tetrasulfide, dipentamethylene thiuram hexasulfide, tetrabutyl thiuram disulfide, pentamethylene thiuram tetrasulfide, and any one thiuram-based compound selected from the group consisting of a combination thereof may be used.

As the thiourea-based curing accelerator, for example, any one thiourea-based selected from the group consisting of thiacarbamide, diethylthiourea, dibutylthiourea, trimethylthiourea, diorthotolylthiourea, and combinations thereof Compounds can be used.

As the guanidine-based vulcanization accelerator, for example, any one guanidine-based compound selected from the group consisting of diphenylguanidine, diorthotolylguanidine, triphenylguanidine, orthotolylbiguanide, diphenylguanidine phthalate, and combinations thereof can be used. I can.

Examples of the dithiocarbamic acid-based vulcanization accelerator include zinc ethylphenyldithiocarbamate, zinc butylphenyldithiocarbamate, sodium dimethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, Zinc dibutyldithiocarbamate, zinc diamyldithiocarbamate, zinc dipropyldithiocarbamate, complex salt of zinc pentamethylenedithiocarbamate and piperidine, zinc hexadecylisopropyldithiocarbamate, octadecyl Zinc isopropyldithiocarbamate, zinc dibenzyldithiocarbamate, sodium diethyldithiocarbamate, piperidine pentamethylenedithiocarbamate, selenium dimethyldithiocarbamate, tellurium diethyldithiocarbamate, dia Any one dithiocarbamic acid-based compound selected from the group consisting of cadmium mildithiocarbamate and combinations thereof may be used.

The aldehyde-amine-based or aldehyde-ammonia-based vulcanization accelerator is, for example, an aldehyde selected from the group consisting of acetaldehyde-aniline reactant, butylaldehyde-aniline condensate, hexamethylenetetramine, acetaldehyde-ammonia reactant, and combinations thereof -Amine-based or aldehyde-ammonia-based compounds can be used.

As the imidazoline-based vulcanization accelerator, an imidazoline-based compound such as 2-mercaptoimidazoline may be used, and as the xanthate-based vulcanization accelerator, for example, a xanthate-based zinc dibutylxanthogenate or the like can be used. Compounds can be used.

The vulcanization accelerator may be included in an amount of 0.5 to 4.0 parts by weight based on 100 parts by weight of the raw rubber in order to maximize productivity and rubber properties through acceleration of the vulcanization speed.

The vulcanization accelerator aid is a blending agent used in combination with the vulcanization accelerator to complete the accelerating effect, and any one selected from the group consisting of inorganic vulcanization accelerators, organic vulcanization accelerators, and combinations thereof may be used. .

As the inorganic vulcanization accelerator, any one selected from the group consisting of zinc oxide (ZnO), zinc carbonate, magnesium oxide (MgO), lead oxide, potassium hydroxide, and combinations thereof can be used. have. The organic vulcanization accelerator is selected from the group consisting of stearic acid, zinc stearate, palmitic acid, linoleic acid, oleic acid, lauric acid, dibutyl ammonium oleate, derivatives thereof, and combinations thereof. You can use any one of them.

In particular, the zinc oxide and the stearic acid may be used together as the vulcanization accelerator, and in this case, the zinc oxide is dissolved in the stearic acid to form an effective complex with the vulcanization accelerator, thereby reducing advantageous sulfur during the vulcanization reaction. It facilitates the crosslinking reaction of the rubber by making it.

When the zinc oxide and the stearic acid are used together, it may be used in an amount of 1 to 10 parts by weight and 0.5 to 3 parts by weight based on 100 parts by weight of the raw rubber, respectively, to serve as an appropriate vulcanization accelerator. When the content of the zinc oxide and the stearic acid is less than the above range, the vulcanization rate may be slow and productivity may decrease, and when the content of the zinc oxide and the stearic acid exceed the above range, a scorch phenomenon may occur and physical properties may be reduced.

The softening agent is added to the rubber composition to facilitate processing by imparting plasticity to the rubber or to reduce the hardness of the vulcanized rubber, and refers to oils and other materials used during rubber compounding or rubber production. The softener means process oil or oils included in other rubber compositions. As the softener, any one selected from the group consisting of petroleum oils, vegetable oils, and combinations thereof may be used, but the present invention is not limited thereto.

As the petroleum oil, any one selected from the group consisting of paraffin oil, naphthenic oil, aromatic oil, and combinations thereof may be used.

Representative examples of the paraffinic oil include P-1, P-2, P-3, P-4, P-5, and P-6 of Michang Oil Co., Ltd., and a representative example of the naphthenic oil is Michang Oil. N-1, N-2, and N-3 of Co., Ltd. may be mentioned, and representative examples of the aromatic oil include A-2 and A-3 of Michang Oil Co., Ltd.

However, it is known that cancer-causing potential is high when the content of polycyclic aromatic hydrocarbons (hereinafter referred to as PAHs) contained in the aromatic oil is 3% by weight or more with the recent increase in environmental awareness, TDAE ( Treated distillate aromatic extract) oil, mild extraction solvate (MES) oil, residual aromatic extract (RAE) oil, or heavy naphthenic oil may be preferably used.

In particular, the oil used as the emollient has a total content of PAHs of 3% by weight or less with respect to the entire oil, a kinematic viscosity of 95 or more (210 μ SUS), an aromatic component in the softener of 15 to 25% by weight, and a naphthenic component. TDAE oil having 27 to 37% by weight and 38 to 58% by weight of a paraffinic component may be preferably used.

The TDAE oil is advantageous in terms of environmental factors such as cancer-causing potential of PAHs while improving low-temperature characteristics and fuel economy performance of tires including the TDAE oil.

The plant oils include castor oil, cottonseed oil, linseed oil, canola oil, soybean oil, palm oil, palm oil, peanut oil, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil , Jojoba oil, macadamia nut oil, saflower oil, tung oil, and any one selected from the group consisting of a combination thereof may be used.

The softening agent is preferably used in an amount of 0 to 10 parts by weight based on 100 parts by weight of the raw rubber in that it improves the processability of the raw rubber.

The anti-aging agent is an additive used to stop a chain reaction in which the tire is automatically oxidized by oxygen. As the anti-aging agent, any one selected from the group consisting of amine-based, phenol-based, quinoline-based, imidazole-based, carbamic acid metal salts, waxes, and combinations thereof may be appropriately selected and used.

Examples of the amine-based anti-aging agent include N-phenyl-N'-(1,3-dimethyl)-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-diaryl-p-phenylenediamine, N-phenyl-N' -Any one selected from the group consisting of cyclohexyl p-phenylenediamine, N-phenyl-N'-octyl-p-phenylenediamine, and combinations thereof may be used. The phenolic antioxidants include phenolic 2,2'-methylene-bis(4-methyl-6-tert-butylphenol), 2,2'-isobutylidene-bis(4,6-dimethylphenol), 2 ,6-di-t-butyl-p-cresol, and any one selected from the group consisting of combinations thereof may be used. As the quinoline-based antioxidant, 2,2,4-trimethyl-1,2-dihydroquinoline and derivatives thereof may be used, and specifically, 6-ethoxy-2,2,4-trimethyl-1,2-di Consisting of hydroquinoline, 6-anilino-2,2,4-trimethyl-1,2-dihydroquinoline, 6-dodecyl-2,2,4-trimethyl-1,2-dihydroquinoline and combinations thereof Any one selected from the group can be used. As the wax, waxy hydrocarbon may be preferably used.

In addition to the anti-aging effect, the anti-aging agent must have a high solubility in rubber, low volatility, and inert to rubber, and not inhibit vulcanization, etc., 1 to 10 parts by weight of the raw rubber. It may be included in parts by weight.

A typical amount of the antioxidant may be included in, for example, about 1 to about 5 parts by weight. Representative antioxidants are, for example, diphenyl-p-phenylenediamine and others, but are not limited thereto.

Referring to FIG. 1, the tire 10 includes a tread part 100, a sidewall part 200, and a bead part 300.

The tread portion 100 is a portion in contact with the ground in cross section, and serves to protect the tire from impact and trauma from the road surface. A plurality of blocks partitioned by grooves may be formed on the surface of the tread portion as described above to improve the drainage characteristics of the tire.

The sidewall 200 and the bead 300 are sequentially positioned on both sides along the width direction of the tire with the tread portion as the center.

The sidewall 200 is a part that extends from both ends of the tread to form side surfaces of the tire, withstands continuously repeated contraction and expansion during driving, and protects the carcass layer 400 located on the inner surface. Do it.

The bead part 300 is provided at both ends of the sidewall 200 to surround the end of the cord paper, and the bead part 300 includes a bead core 500 including a ring-shaped steel wire.

A carcass layer 400 is positioned between the pair of left and right bead portions 300, and is bonded to the tire rubber sheet inside the tire to form the skeleton of the tire, and the carcass layer 400 is the bead core 500 ) It is winding up from the inside of the tire to the outside.

An inner liner 700 is located on one side of the inner side of the carcass layer 400 and serves to prevent air inside the tire from escaping to the outside.

In the inner liner 700, a rubber composition according to an embodiment of the present invention is used.

The belt layer 600 is positioned on the outer surface of the carcass layer 400 located on the tread unit 100 as a reinforcing layer that increases the elasticity of the tread and has maneuverability and stability.

The belt layer rubber may include a cobalt compound, and the cobalt compound is a cobalt salt, a cobalt-boron ester, an organic acid cobalt salt, an inorganic acid cobalt salt, a non-cobalt salt, and the like, and as an adhesion system, cobalt salt alone, cobalt- In addition to RH and cobalt-HRH, resins (e.g., methylene acceptor: phenolic, resorcinol, cresol, etc., or donor: hexamethylenetetraamine (HMT), hexamethoxymethylmelamine (HMMA), pentamethoxymethyl) Melamine (PMMA)] modified adhesive system.

In general, to improve adhesion, improve the adhesion system of the adhesive compound rubber (cobalt-RH, cobalt-HRH, their modification system), improve the resin used as an adhesion aid and improve the performance, improve the cobalt salt used as the adhesion aid, adhesion Improvements in the vulcanization system of rubber and the use of new compounding compositions (reinforcing agents, carbon black, silica, polymers, and chemicals) are being used.

The content of the cobalt compound may include 0.2 to 5.0 parts by weight based on 100 parts by weight of the raw rubber, but is not limited thereto.

A cap ply 800 including a hybrid cord may be disposed between the belt layer 600 and the tread portion 100. The cap ply 800 may suppress the flow of the belt layer 600 while driving to maintain the performance of the tire.

The tire inner liner rubber composition may be prepared through a three-step manufacturing process, and may be prepared through a one-step, conventional two-step continuous production process of producing a dopamine-modified carbon powder. That is, during the first step of thermomechanical treatment or kneading at a maximum temperature ranging from 50 to 190°C, preferably at a high temperature of 80 to 150°C and the finishing step in which the crosslinking system is mixed, typically less than 110°C, for example It may be prepared in a suitable mixer using the second step of mechanical treatment at a low temperature of 40 to 100°C, but is not limited thereto.

A tire according to another embodiment of the present invention includes the step of using the rubber composition for a tire inner liner when forming a green tire. The method of forming a green tire using the rubber composition for a tire inner liner can be applied to any method as long as it is a method conventionally used for manufacturing a tire, and a detailed description thereof will be omitted in the present specification.

1 illustrates a tire for a passenger car, but is not limited thereto, and may be a tire for a passenger car, a tire for a race, an airplane tire, a tire for agricultural machinery, an off-the-road tire, a truck tire, a bus tire, and the like. have. In addition, the tire may be a radial tire or a bias tire, preferably a radial tire.

The present invention will be described in more detail through the following examples and comparative examples. However, the examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Dopamine Modified Graphene Produce

5.0 g of graphene oxide and 1.5 g of dopamine were added to 500 ml of DI-Water, and the pH was maintained at 8.5 and stirred at 60° C. for 24 hours.

Thereafter, the mixture was freeze-dried (lyophilization) to obtain dopamine-modified graphene.

Graphene oxide before modification had a dark yellow color, but graphene after modification had a black color.

Comparative example 1, 2 and Example One

Each of the components in Table 1 below was added to a Banbury mixer in the ratio (unit: parts by weight) and mixed. After all the ingredients were added to the Tangential type Banbury mixer, the ratio of each ingredient was adjusted so that the fill factor of 1.65L capacity was 0.65 to 0.70.

division Comparative example One Comparative example 2 Example One caoutchouc 20 20 20 Butyl rubber 80 80 80 Carbon Black ^{1 )} 60 55 55 Mg silicate 30 30 30 normal graphene ²⁾ - 3.0 - Dopamine-modified graphene - - 3.0 Adhesive ³⁾ 2.0 2.0 2.0 Oil ⁴⁾ 11 11 11 zinc oxide 3.0 3.0 3.0 Stearic acid 0.02 0.02 0.02 sulfur 1.0 1.0 1.0 Accelerator ^{5 )} 1.0 1.0 1.0

1) N660

2) unmodified graphene

3) C5 resin

4) RAE oil

5) Accelerator: 2,2'-DITHIOBISBENZOTHIAZOLE

Evaluation example

Basic physical properties

The unvulcanized rubber prepared in Example 1 and Comparative Examples 1 and 2 was prepared in a curing machine at 180° C. for 10 minutes. For each vulcanized specimen, the physical properties were evaluated as follows, and the results are shown in Table 2 below.

Hardness

According to ASTM D2240-97, a single specimen was measured five times on a smooth surface with a thickness of 6 mm using a Shore A hardness tester, and the average value was determined.

Tensile properties

The measurement of the tensile strength of the crosslinked specimen was performed according to ASTM D412 using a tensile tester (INSTRON). The specimen for measurement was manufactured in a sheet form using a hydraulic press and a dumbbell type using a specimen cutter. Test conditions were measured at room temperature at a tensile speed of 500 mm/min

100% Modulus

In the tensile test, the stress value at 100% elongation was expressed, and the force received per unit area was measured.

Elongation

Elongation refers to the elongation rate when the test piece is cut in a tensile testing machine.

Viscoelasticity

The Tan δ Max peak is generally referred to as Tg (Glass Transition Temperature) in DMA, and represents the peak in the temperature-Tan δ graph, and E'' (Loss modulus) is the highest point. Tan δ @ 60℃ refers to tanδ when the temperature is 60℃ in the temperature-Tan δ graph, and is used as a characteristic for fuel economy.

division Comparative example One Comparative example 2 Example One Hardness 62 63 65 100% modulus (kg/cm2) 23 24 25 Tensile strength (kg/cm2) 84 90 100 Elongation (%) 509 519 550 Tan δ Max peak -24 -20 -20 Tan δ @ 60℃ 0.3 0.25 0.20

Referring to Table 2, in terms of basic physical properties, it can be seen that Example 1 is equivalent to or higher than Comparative Examples 1 and 2.

Crack resistance

The unvulcanized rubber was prepared by producing a vulcanized specimen at 180° C. for 10 minutes in a vulcanizing machine, and measured by averaging the crack growth length (mm) two times after being stretched 10,000 times under a specific condition using a Demattia Flexometer equipment.

adhesiveness

The unvulcanized rubber composition was measured by measuring the adhesive force between rubbers four times using a tackness tester equipment, and averaged.

Air permeability

After preparing a specimen by vulcanizing the unvulcanized rubber composition to a thickness of 1 mm at 180° C. for 10 minutes, the air permeability was evaluated using a gas-permeability equipment.

Crack resistance , Adhesion and air permeability test

The adhesion was evaluated for the unvulcanized rubber prepared in Example 1 and Comparative Examples 1,2, and after preparing a specimen with each unvulcanized rubber composition, air permeability and crack resistance were evaluated, and the results are shown in Table 3. I got it.

division Comparative example One Comparative example 2 Example One Crack growth 10000 times (mm) 5.47 3.81 2.49 Adhesion (kgf) 0.580 0.811 1.091 Air permeability (P) 6.52 5.01 (123%) 3.21 (151%)

From the above results, it can be seen that the rubber composition for an inner liner of the embodiment of the present invention has superior crack resistance, adhesion, and air permeability than Comparative Examples 1 and 2.

This is because unmodified graphene has only the interaction between rubber and Van der Waals attraction, but in the case of the dopamine-modified graphene of the present invention, other functional groups such as catechol group and amine group are introduced into graphene with more various forces. This is because it interacts with the rubber and as a result, the adhesion with the carcass is improved. As a result, the air permeability was also improved.

Therefore, in the case of manufacturing a tire using the rubber composition for an inner liner of the present invention, the air permeability of the inner liner is improved, thereby preventing known leakage in the final product, the tire, which can be of great help in maintaining durability.

As described above, although it has been described with reference to preferred embodiments of the present invention, those skilled in the art will variously modify the present invention within the scope not departing from the spirit and scope of the present invention described in the following claims. Or it can be implemented by modification.

10: tire
100: Tread
200: side wall part
300: bead part
400: carcass layer
500: bead core
600: belt layer
700: inner liner
800: cap fly

Claims (10)

Dopamine-modified carbon powder. The method of claim 1,
The carbon powder is a carbon powder comprising carbon black, fullerene, CNT, graphene oxide, graphene, or any combination thereof. The method of claim 1,
The dopamine-modified carbon powder
Carbon powder obtained by adding dopamine and carbon powder in a solvent and reacting at a temperature of 50 to 140° C. for 1 to 72 hours. The method of claim 3,
Carbon powder in which the solvent is water or polyol. The method of claim 4,
The polyol (polyol) is a carbon powder containing ethylene glycol (Ethylene Glycol), diethylene glycol (Diethylene Glycol), triethylene glycol (Triethylene Glycol), tetraethylene glycol (Tetraethylene Glycol, or any combination thereof. The method of claim 3,
Carbon powder in which the reaction is carried out under basic conditions. The method of claim 3,
Carbon powder in which the reaction is carried out at pH 7.7 to 11. The method of claim 3,
The weight ratio of the dopamine and the carbon powder is 1: 99 to 99: 1 carbon powder. A rubber composition for a tire inner liner comprising the dopamine-modified carbon powder of claim 1. A tire made of the rubber composition for a tire inner liner of claim 1.

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