KR20110067233A - Rubber compositions for tire inner liner improving mechanical properties and air permeability - Google Patents

Abstract

PURPOSE: A rubber composition for a tire inner liner is provided to improve mechanical properties and gas permeability and to reduce the weight while enhancing the performance of tire. CONSTITUTION: A rubber composition for a tire inner liner includes 100 parts by weight of a base rubber selected from the group consisting of natural rubber including at least one halobutyl rubber, synthetic rubber and their mixture; and 0.1-10 parts by weight of exfoliated graphite, expandable graphite or their combination as a reinforcing agent. The exfoliated graphite or expandable graphite has the surface area of 10-3000 m^2/g.

Description

Rubber composition for tire inner liner with improved mechanical properties and gas permeability {RUBBER COMPOSITIONS FOR TIRE INNER LINER IMPROVING MECHANICAL PROPERTIES AND AIR PERMEABILITY}

The present invention relates to a rubber composition for a tire innerliner having improved mechanical properties and gas permeability. More particularly, the present invention relates to a rubber composition for tire innerliner, wherein exfoliated graphite or expanded graphite is applied as a reinforcing filler.

The tire can increase durability by maintaining proper air pressure for a long time, and by using a rubber material having excellent air permeability, the tire can be reduced in weight while maintaining the required air pressure, thereby reducing fuel consumption and tire weight. In particular, for tires for passenger cars, internal air maintenance must be maintained at least 97.5% per month.

In order to play such a role in a tire, an inner liner formed of a rubber composition containing halobutyl rubber having excellent air permeation resistance is used.

Passenger car tires use halobutyl rubber with excellent air holding performance to meet the pneumatic holding capacity requirements of the tire.However, halobutyl rubber is expensive and has poor rolling processability. The thickness is determined so as to maintain the innerliner rolling standard without deformation during tire manufacturing at about 60 to 80%, and is designed in consideration of uniformity of material cost and quality.

However, as the environmental problem has recently emerged as a global problem, all industrial products are required to be changed to environment-friendly products, and in the tire field, tires are required to be lighter due to increased fuel consumption and environmental pollution.

In particular, the low air permeability is recognized as one of the most important physical properties of the inner liner as it keeps the tire pressure constant and improves the driving stability as well as reduces the fuel economy due to the reduction of tire rolling resistance and the thickness of the inner liner. .

Conventional rubber compositions for tire innerliner are butyl rubber, butyl rubber / natural rubber, butyl rubber / synthetic rubber, and recently, researches to improve gas permeability using various additives or reinforcing agents are underway.

In the concept of filler, ordinary clay or calcium carbonate (CaCO ₃ ) containing more than 98% by weight of clay (Al ₂ O ₃ · mSiO ₂ · nH ₂ O) is added to the rubber composition for innerliner to maintain air permeability. Rather than improving physical properties, there is a content that relates to a composition that serves to lower the price of the rubber composition by increasing the volume.

However, when the added amount is above a certain level, not only causes a sudden drop in physical properties but also a problem that the rubber composition is broken at low temperatures.

 In addition, the Republic of Korea Patent No. 10-0788033 and Republic of Korea Patent Publication No. 10-2007-0037216 discloses a rubber composition to improve the gas permeability by applying nano clay or nano filler. However, in the case of the present invention, a hydrophilic group nanoclay, a coupling agent for organicizing the nano filler or a special process for the organicization is required, and even if organic nanoclay has a disadvantage that the dispersibility is significantly lower than the general reinforcing agent.

In addition, Korean Patent No. 10-0837864 discloses a rubber composition in which gas permeability is improved by using a partially crosslinked butyl rubber. However, in the case of the present invention, an additional step for partial crosslinking of the raw rubber is required and may cause an increase in cost and a problem of fairness.

Therefore, the present inventors, while studying a method that can solve the problems of the prior art as described above, in the case of applying exfoliated graphite or expanded graphite to the rubber composition for tire innerliner as a reinforcing filler, not only mechanical properties but also gas permeability The present invention has been completed by discovering that it can be improved.

Accordingly, the present invention is to provide a rubber composition for a tire innerliner by applying exfoliated graphite or expanded graphite as a reinforcing filler to improve not only mechanical properties but also gas permeability.

In order to solve the above technical problem, the present invention reinforces 100 parts by weight of the raw material rubber selected from the group consisting of natural rubber, synthetic rubber and mixtures thereof including at least one halobutyl rubber in the rubber composition for tire inner liner It provides a rubber composition for a tire innerliner comprising 0.1 to 10 parts by weight of exfoliated graphite, expanded graphite or a combination thereof as a filler.

In the rubber composition for a tire innerliner according to the present invention, the exfoliated graphite or expanded graphite preferably has a surface area of 10 to 3000 m ² / g.

In addition, in the rubber composition for a tire inner liner according to the present invention, it is preferable that the raw material rubber forms a composite rubber together with a surfactant or a fatty acid which is anionic, cationic, nonionic, or a mixture thereof.

The present invention can provide a rubber composition for a tire innerliner having improved mechanical properties and gas permeability by applying exfoliated graphite or expanded graphite having a flat plate structure to a conventional rubber composition for tire innerliner as a reinforcing filler. .

In addition, the present invention can increase the performance and reduce the weight of the tire by providing a rubber composition for a tire innerliner with improved mechanical properties and gas permeability.

Hereinafter, the present invention will be described in more detail.

In the rubber composition for tire inner liner, the present invention comprises 0.1 to 10 parts by weight of exfoliated graphite, expanded graphite or a combination thereof as 100 parts by weight of the raw material rubber.

Peeled graphite or expanded graphite used as reinforcing filler in the present invention has a plate-like structure as shown in FIG. Representative of the exfoliated graphite is graphene (Graphene), the expanded graphite refers to the graphite expanded hundreds of times than the initial volume. The exfoliated graphite or expanded graphite is an allotrope with carbon black, the strength of which is incomparable with that of carbon black, and exhibits excellent tensile strength, high elasticity, high conductivity, and the like at the same mass.

The exfoliated graphite or expanded graphite is bonded to three carbon atoms adjacent to one carbon atom, and a hexagonal ring is formed by the bond between the carbon atoms, and they are a plane-like material that is repeated in a honeycomb form. Such exfoliated graphite or expanded graphite has a large surface area, and its surface area is in the range of 10 to 3000 m ² / g, and because of the large surface area, when the same amount is uniformly dispersed, high thermal, mechanical and physical properties are improved. It appears large.

The exfoliated graphite or expanded graphite is preferably used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the raw material rubber. When exfoliated graphite or expanded graphite having a flat structure of less than 0.1 part by weight is added, it is not expected to improve the air permeability characteristics of the rubber by adding them, and when used in excess of 10 parts by weight, There exists a possibility that the fall of dispersibility and a physical property may arise.

The exfoliated graphite or expanded graphite is preferably used in combination with carbon black, which is a general purpose reinforcing material in this field.

In the rubber composition for a tire inner liner according to the present invention, any material can be used as long as the raw material rubber can be used as a raw material for the tire inner liner rubber composition. As an example of such raw rubber, natural rubber, butyl rubber, halogenated butyl rubber may be used or may be used by mixing thereof. Among these, synthetic rubber, natural rubber, a mixture of synthetic rubber and natural rubber are suitable, and more preferably, the raw material rubber contains at least one halobutyl rubber.

In addition, in the rubber composition for a tire inner liner according to the present invention, it is preferable that the raw material rubber forms a composite rubber together with a surfactant or a fatty acid which is an anionic, cationic, nonionic, or a mixture thereof.

In addition, the rubber composition for a tire inner liner according to the present invention may be added by mixing galvanized, stearic acid, anti-aging agent, processing oil, vulcanizing agent, vulcanization accelerator and the like as necessary, but is not limited thereto.

 Hereinafter, the present invention will be described by the following examples and comparative examples. However, these are not limited to the scope of the present invention by these as an embodiment of the present invention.

Example  One

70 parts by weight of universal carbon black was added based on 100 parts by weight of the raw material rubber, 2 parts by weight of graphene was added, and the remaining additives were introduced by referring to the contents shown in Table 1 below to prepare rubber specimens.

Comparative example  One

Based on 100 parts by weight of the raw material rubber, 70 parts by weight of N660 having excellent gas permeability among general carbon black was added, and the remaining additives were introduced by referring to the contents shown in Table 1 below to prepare rubber specimens.

Comparative example  2

Based on 100 parts by weight of the raw material rubber, 72 parts by weight of N660 having excellent gas permeability in general carbon black was added, and the remaining additives were introduced by referring to the contents shown in Table 1 below to prepare rubber specimens.

Comparative example  3

70 parts by weight of universal carbon black was added based on 100 parts by weight of the raw material rubber, 2 parts by weight of carbon nanotubes were added, and the remaining additives were added with reference to the contents shown in Table 1 below to prepare rubber specimens.

Comparative example  4

70 parts by weight of universal carbon black was added based on 100 parts by weight of the raw material rubber, 2 parts by weight of graphite was added, and the remaining additives were introduced by referring to the contents shown in Table 1 below to prepare rubber specimens.

division
(Parts by weight) Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Butyl rubber 60 60 60 60 60 Natural rubber 40 40 40 40 40 Stearic acid One One One One One General purpose carbon black
(N660) 70 70 72 70 70 Carbon Nano Tube 0 0 0 2 0 Graphene 2 0 0 0 0 Graphite 0 0 0 0 2 oil 10 10 10 10 10 Processing aid 8 8 8 8 8 Vulcanization accelerator 2 2 2 2 2 brimstone One One One One One Zincification 5 5 5 5 5

Test Example  One

After pressing the rubber composition of Example 1 and Comparative Examples 1 to 4 prepared by using the rubber compound of Table 1 for 10 minutes by hot press (hot press) to make a plate of thickness 3mm and then vulcanization time according to ASTM-related regulations , Maximum torque, hardness, 300% modulus, tensile strength, elongation, gas permeability, etc. were measured and the test results are described in Table 2.

Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Mechanical
Properties Shore A 73 67 69 67 68 300% modulus
(kgf / cm2) 72 52 54 55 49 The tensile strength
(kgf / cm2) 79 78 79 79 84 % Elongation 350 370 360 350 410 Gas Permeation Rate (E ^-17 ) 7.87 10.51 10.01 9.51 9.59 The unit of gas permeability is m ⁴ / sec · N and the measurement condition is 4psi, 60 ℃

In Table 2, the hardness means that the higher the hardness, the higher the numerical value for the tensile properties (300% modulus, tensile strength, elongation) means that the respective properties are excellent. In addition, the gas permeability means that the lower the value is excellent.

 In the rubber prepared by the inner liner rubber composition of the present invention as shown in Table 2, the result of the test example, Example 1 to which exfoliated graphite or expanded graphite is equal to or more than physical properties compared to rubbers of Comparative Examples 1 to 4 It can be seen that it can improve the air permeability in particular.

In addition, when the same raw material rubber is used, 2 parts by weight of exfoliated graphite (graphene, graphene) or expanded graphite may be added to improve gas permeability of about 35% or more.

Therefore, the use of exfoliated graphite or expanded graphite in the rubber composition for tire innerliner can replace butyl rubber or reduce the amount of use, thereby increasing the performance of the tire and reducing the weight.

As described above, the inner liner rubber composition for tires having improved mechanical properties and gas permeability as a preferred embodiment of the present invention has been described, but the present invention is not limited to the specific preferred embodiments described above, and is claimed in the claims. Without departing from the gist of the present invention, any one of ordinary skill in the art to which the present invention pertains can make various modifications, and such changes are included within the technical scope of the claims. have.

1 is a photograph taken with an electron microscope of peeled graphite or expanded graphite used as a reinforcing filler in the rubber composition for a tire innerliner of the present invention.

Claims (3)

In the rubber composition for tire inner liner, 0.1 to 10 parts by weight of exfoliated graphite, expanded graphite or a combination thereof as 100 parts by weight of a raw material rubber selected from the group consisting of natural rubber, synthetic rubber and mixtures thereof including at least one halobutyl rubber. A rubber composition for a tire innerliner comprising a. The method of claim 1, The exfoliated graphite or expanded graphite has a rubber composition for a tire inner liner, characterized in that it has a surface area of 10 to 3000m ² / g. The method of claim 1, The raw rubber is a rubber composition, characterized in that in the form of a composite rubber with a surfactant, anionic, cationic, nonionic, or a mixture thereof or a fatty acid.

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