KR20220040093A - Rubber composition for repairing a tire tread and method of repairing the tire tread by using the rubber composition - Google Patents

Abstract

Provided is a rubber composition for repairing a tire tread which has improved abrasion resistance and reduces retreading time. The rubber composition for repairing a tire tread comprises 100 parts by weight of soft urethane and 50 to 100 parts by weight of a curing agent.

Description

RUBBER COMPOSITION FOR REPAIRING A TIRE TREAD AND METHOD OF REPAIRING THE TIRE TREAD BY USING THE RUBBER COMPOSITION

The present invention relates to a rubber composition for repairing a tire tread for all seasons, and specifically, it is possible to prepare a rubber composition for repairing a tire tread under conditions of no high temperature and high pressure without using any additives, and the abrasion resistance of the repaired tire is improved. It relates to a rubber composition for tire tread repair that can reduce the retreading time.

According to the recent abnormal high temperature phenomenon, unlike in the past, the wear amount of tire rubber tends to increase. Tires, which are subjected to various external shocks from the ground and the environment, are the only parts that connect the vehicle and the road surface, and are made by combining various rubbers and cords to support load, drive, change direction, and mitigate impact. In particular, rubber properties may be sensitive to changes in temperature, and wear performance may affect driving performance.

In general, when the tread of a tire wears to a certain extent, the grip of the tire on the road surface is significantly reduced, especially when it is wet. Worn tires are excluded from use for safety reasons.

As a technology of retreading, instead of abandoning a worn tire and replacing it with a new tire, there are two regeneration methods: hot cure and cold cure of new tread rubber to the worn tire. .

The heat vulcanization regeneration method is a method of attaching new, unvulcanized tread rubber to the worn tire and manufacturing it in a vulcanization condition at a high temperature of about 130 ° C or higher in a mold engraved with a pattern. This is a method of manufacturing the new vulcanized and completed tread rubber under low-temperature vulcanization conditions of 120°C or less.

However, when using the retreading technology, the cost of remanufacturing the tread increases, and in particular, in the case of the thermal vulcanization regeneration method, there is a limitation that high temperature conditions must be accompanied by various additives added.

Therefore, various attempts have been made in each tire manufacturing industry to repair tire tread worn under room temperature conditions instead of high temperature conditions. At the same time, research on reducing the retreading time is still insufficient.

It is an object of the present invention to provide a rubber composition for tire tread repair in which a soft urethane and a curing agent are mixed, so that the rubber composition for tire tread repair is capable of running under low load and low speed conditions and has improved abrasion resistance. to provide tires that

Another object of the present invention is to provide a rubber composition for repairing a tire tread that shortens a retreading time by mixing a soft urethane and a curing agent.

Another object of the present invention is to repair a worn tire tread by providing a rubber composition for repairing a tire tread in a chamber at room temperature using salt, which is an eco-friendly material and a sustainable material.

The present invention also provides a rubber composition for repairing a tire tread capable of re-treading without maintaining a high-temperature condition as no additives are added, and a method of repairing a tire using the same.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned may be understood by the following description, and will be more clearly understood by the examples of the present invention. Moreover, it will be readily apparent that the objects and advantages of the present invention may be realized by means of the instrumentalities and combinations thereof indicated in the appended claims.

To achieve the above object, a rubber composition for repairing a tire tread according to the present invention includes: 100 parts by weight of soft urethane; and 50 to 100 parts by weight of a curing agent.

It is an object of the present invention to provide a rubber composition for tire tread repair in which a soft urethane and a curing agent are mixed, so that the rubber composition for tire tread repair is capable of running under low load and low speed conditions and has improved abrasion resistance. to provide tires that

Another object of the present invention is to provide a rubber composition for repairing a tire tread that shortens a retreading time by mixing a soft urethane and a curing agent.

Another object of the present invention is to repair a worn tire tread by providing a rubber composition for repairing a tire tread in a chamber at room temperature using salt, which is an eco-friendly material and a sustainable material.

The present invention also provides a rubber composition for repairing a tire tread capable of re-treading without maintaining a high temperature condition as no additives are added, and a method for repairing a tire tread using the same.

In addition to the above-described effects, the specific effects of the present invention will be described together while explaining the specific contents for carrying out the invention below.

Hereinafter, each configuration of the present invention will be described in more detail so that those of ordinary skill in the art to which the present invention pertains can easily carry out, but this is only an example, and the scope of the present invention is defined by the following contents Not limited.

The rubber composition for repairing a tire tread according to the present invention is a rubber composition for repairing a tire tread comprising a soft urethane and a curing agent, and the rubber composition for repairing a tire tread includes 100 parts by weight of the flexible urethane and 50 to 100 parts by weight of a curing agent.

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

[Soft Urethane]

Flexible urethane is one of the types of polyurethane, and the polyurethane is a high molecular compound and is a foamed product obtained by using polyol and isocyanate as main materials.

The polyol refers to a liquid polymer material having two or more alcohol groups attached to a hydrocarbon chain. For example, the polyol may include ethylene glycol or propylene glycol etherified diethylene glycol, dipropylene glycol, polyethylene glycol, and the like.

The isocyanate has two or more isocyanate groups, and may be used to improve the properties of the final polymer by partially reacting with the polyol.

Soft urethane has an open cell structure, so it has good air permeability and good cushioning properties, and can have a wide range of specific gravity and various physical properties and mechanical strength depending on the formulation. Specifically, the mechanical strength may correspond to elongation, tensile strength, and abrasion resistance.

Flexible urethane can be classified into slab stock foam and mold foam. The slab stock foam means a foam that is freely foamed without injecting the stock solution into the mold, and the cured foam is cut into a desired shape and used. means the form The flexible urethane according to the present invention is preferably manufactured by the above-mentioned mold form method having excellent moldability.

The flexible urethane according to the present invention may have a hardness of Shore A50 to Shore A85 before curing. More preferably, the hardness of the soft urethane may correspond to Shore A60 to Shore A70 (Shore A70). When the hardness of the soft urethane exceeds the above numerical range, it may be difficult to cure with styrene-butadiene latex, which will be described later.

In addition, the viscosity of the flexible urethane according to the present invention may correspond to 70 to 90 centipoise (cPS). More preferably, the viscosity of the flexible urethane may correspond to 75 to 85 centipoise (cPS). When the viscosity of the flexible urethane is lower than the numerical range, solidification may be difficult even if it reacts with a curing agent to be described later, and if the numerical viscosity is exceeded, the abrasion resistance may not be improved.

[hardener]

The curing agent according to the present invention may correspond to a urethane-only curing agent for curing flexible urethane. Physical properties of the curing agent may be determined according to the type and number of functional groups, and the structure and weight molecular weight of molecules.

For example, the urethane-only curing agent may correspond to a monohydric alcohol, a polyol, a polyamine, etc., and the type of the alcohol and the amine is not limited. In addition, the urethane-only curing agent may correspond to a resin composition applied to a conventional two-component urethane resin, and an aromatic isocyanate having two or more isocyanate groups and two to three active hydroxyl groups and a molecular weight of 1000 to 4000 Polyol compounds. constituted isocyanate pre-polymers. The prepolymer means a partially polymerized resin for casting, such as polymethyl methacrylate and allyl resin.

The curing agent according to the present invention may include 50 to 100 parts by weight of the curing agent based on 100 parts by weight of the flexible urethane.

The rubber composition for repairing a tire tread according to the present invention may contain no additives. Specifically, the treatment may correspond to at least one selected from the group consisting of silica, coupling agent, process oil, zinc oxide, stearic acid, sulfur, and accelerator.

Conventionally, in manufacturing a rubber composition for repairing a tire tread, since synthetic rubber and various additives are added, there is a problem in that the retreading time is relatively long.

In addition, the thermal vulcanization method, which is a regenerative tire method, is a method of attaching a new tread rubber to a worn tire tread and manufacturing it under vulcanization conditions in a mold structure engraved with a pattern. . Due to this, there was a physical limitation that a customer could not attach the mold structure of the same pattern to the worn tire tread anytime, anywhere.

Alternatively, the rubber composition for repairing a tire tread according to the present invention can repair a tire tread in a chamber at room temperature. The rubber composition for repairing a tire tread does not include a material, so that the tire tread may be repaired under the condition that the temperature in the chamber is 11 to 32°C. More preferably, the temperature in the chamber corresponds to 23 to 28 °C. When the temperature of the chamber is less than 11°C, the reaction rate at which the flexible urethane is cured may be remarkably slowed, and if it exceeds the temperature range of 32°C, the abrasion resistance of the tire tread may not be improved.

[Styrene-Butadiene Latex]

The rubber composition for repairing a tire tread according to the present invention may further include styrene-butadiene latex in addition to the soft urethane and the curing agent. More preferably, the styrene-butadiene latex may include 70 to 130 parts by weight based on 100 parts by weight of the soft urethane. When styrene-butadiene latex is added in a smaller amount than the above content based on 100 parts by weight of the flexible urethane, the tire tread repaired with the tire tread repair rubber composition may become too hard and break. When the styrene-butadiene latex is added in excess of the above content relative to 100 parts by weight of the flexible urethane, the tire tread becomes too soft to support a high-load automobile.

Styrene-butadiene latex may have a greater crosslink density than styrene-butadiene rubber. Accordingly, the styrene-butadiene latex may have greater tensile strength than the styrene-butadiene rubber. For this reason, the abrasion resistance of the tire tread repair rubber according to the present invention containing the styrene-butadiene latex may be improved. On the other hand, the crosslinking density refers to the ratio of the number of crosslinking points that are structural units that are crosslinked in the crosslinked polymer to the total number of structural units. Therefore, the crosslinking density corresponds to an important factor for measuring the structure of a polymer of a certain part.

On the other hand, the styrene-butadiene latex according to the present invention may correspond to a general form of a styrene-butadiene emulsion (styrene-butadiene emulsion) polymer.

[salt]

The rubber composition for repairing a tire tread according to the present invention may additionally include salt in addition to the soft urethane and the curing agent. More preferably, the salt may include 0.1 to 10 parts by weight based on 100 parts by weight of the soft urethane. When salt is added in excess of the above content relative to 100 parts by weight of soft urethane, a problem may occur that the salt is exposed to the surface and becomes the starting point of cracks during driving.

The salt according to the present invention may correspond to sea salt made by drawing seawater into a salt farm and evaporating only moisture with wind and sunlight. The sea salt is thick and translucent hexagonal crystals. Specifically, salt is sodium chloride (NaCl), which is a cubic crystal formed by combining sodium and chlorine in the same ratio.

The salt according to the present invention is an eco-friendly material and corresponds to a sustainable material, and is a material that a customer can easily purchase. In addition, the salt can control the reaction rate by speeding up the reaction rate of the styrene-butadiene latex. Specifically, when the styrene-butadiene latex reacts with the soft urethane and the curing agent, the salt may solidify the composition including the styrene-butadiene latex.

In the process of manufacturing the rubber composition for tire tread repair according to the present invention, the salt may be prepared by various methods such as the sun-dried decontamination method, the electric decontamination method, the freezing decontamination method, and the ion exchange membrane method, and the technical idea of the present invention is However, the present invention is not limited thereto.

The rubber composition for tire tread repair according to the present invention may additionally include styrene-butadiene latex and salt, thereby providing a tire with improved wear resistance. Specifically, the tire tread repaired with the tire tread repair rubber composition may secure a property improved in abrasion resistance by 10% or more while maintaining adhesion to the existing rubber.

Hereinafter, a method of repairing a tire tread using the rubber composition for repairing a tire tread according to the present invention will be described below.

A tire tread repair method according to the present invention may include forming a mold structure in a chamber. Specifically, the mold structure may correspond to the same pattern as a tire tread having a desired shape. The mold structure according to the present invention may be formed by 3D printing (Three Dimensional Printing) technology, but is not limited thereto, and various methods may be used.

On the other hand, 3D printing technology is a technology that extracts objects with a printer using materials that can make three-dimensional figures such as plastic, nylon, metal, and rubber inside.

In particular, the use of 3D printing technology has the advantage that it is possible to implement a pattern desired by the customer during wear. In addition, the 3D printing technology may enable manufacturing of a mold structure suitable for the shape of a worn tire tread by overcoming the peculiarity that the linear pattern of the tread is difficult to form in the shape of a spherical tire.

A worn or damaged tire may be placed on the mold structure. Specifically, the rubber composition for repairing a tire tread may be injected between the mold structure and the tire to undergo a curing reaction to be hardened. A mixing kit may be used in the process of inputting the rubber composition for tire tread repair.

Accordingly, the customer can purchase the mixture kit to repair worn tires without time and place restrictions.

In particular, when styrene-butadiene latex and salt are added to the rubber composition for repairing a tire tread according to the present invention, the salt acts as a curing agent, so that the abrasion resistance of the rubber composition can be further improved.

Meanwhile, in the tire tread repair method according to the present invention, a target tire can support a load of less than 500 kg per unit. More preferably, the tire can support a load of less than 450 kg per tire.

Hereinafter, a tire including the rubber composition for repairing a tire tread according to the present invention will be described below.

A tire including the tire tread repair rubber composition according to the present invention can withstand a load of less than 500 kg (kilogram) per tire. More preferably, it can withstand a load of less than 450 kg per tire. Therefore, the rubber composition for tire tread repair according to the present invention can be applied to low-load automobiles such as golf carts, Segways, and single-seater personal mobility.

Meanwhile, a tire including the tire tread repair rubber composition according to the present invention may be a tire used in a low speed region. Specifically, the low-speed region may correspond to 150 km/h or less, and more preferably correspond to 120 km/h.

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily carry out, but this is only an example, and the scope of the present invention is defined by the following contents Not limited.

[Production Example]

Tire treads were repaired with the rubber compositions for repairing tire treads according to Examples and Comparative Examples with the composition shown in Table 1 below. Meanwhile, Table 2 below shows the load supported by the tire repaired with the tire tread repair rubber composition and the temperature conditions of the chamber during the curing reaction.

<Example 1>

Example 1 is a rubber composition for repairing a tire tread in which 50 parts by weight of a curing agent exclusively for urethane is added to the flexible urethane based on 100 parts by weight of the flexible urethane.

Meanwhile, a curing reaction was performed on the composition under the condition that the chamber temperature was 23°C. The load supported by one tire including the composition corresponds to 400 kg.

<Example 2>

Example 2 is a rubber composition for tire tread repair in which 100 parts by weight of a urethane-only curing agent, 100 parts by weight of styrene-butadiene latex, and 6 parts by weight of salt are added to the flexible urethane with respect to 100 parts by weight of the flexible urethane.

Meanwhile, a curing reaction was performed on the composition under the condition that the chamber temperature was 23°C. The load supported by one tire including the composition corresponds to 400 kg.

<Comparative Example 1>

Comparative Example 1 corresponds to a conventional rubber composition for repairing a tire tread including a synthetic rubber and a material. Meanwhile, a curing reaction was performed on the composition under the condition that the chamber temperature was 23°C.

With respect to 100 parts by weight of the composite of synthetic rubber, soft urethane and urethane-specific curing agent, 120 parts by weight of silica, 19 parts by weight of coupling agent, 30 parts by weight of eutectic oil, 3 parts by weight of zinc oxide, 1 part by weight of stearic acid, 2 parts by weight of sulfur , 2 parts by weight of an accelerator is added to the composite.

The load supported by one tire including the composition corresponds to 400 kg.

<Comparative Example 2>

Comparative Example 2 is the same composition as Example 1, but the curing reaction proceeds in the composition at a chamber temperature of 10°C. The load supported by the tire including the composition corresponds to 400 kg.

<Comparative Example 3>

Comparative Example 3 is the same composition as Example 1, but the curing reaction proceeds in the composition at a chamber temperature of 33°C. The load supported by the tire including the composition corresponds to 400 kg.

<Comparative Example 4>

Comparative Example 4 is the same composition as Example 1, but the curing reaction proceeds in the composition at a chamber temperature of 23°C. The load supported by the tire including the composition corresponds to 500 kg.

Comparative Example 1 Example 1 Example 2 Synthetic rubber ¹⁾ 40 - - soft urethane ²⁾ 30 100 50 Urethane-exclusive curing agent ³⁾ 30 50 50 SBR Latex ⁴⁾ - - 50 Salt ⁵⁾ - - 3 silica ⁶⁾ 120 - - coupling agent ⁷⁾ 19 - - Process oil ⁸⁾ 30 - - zinc oxide ⁹⁾ 3 - - stearic acid ¹⁰⁾ One - - sulfur ¹¹⁾ 2 - - accelerator ¹²⁾ 2 - - 1) SBR1739
2) Soft urethane with Shore A hardness of 70 and 80 cPS
3) 1, 3-phenylenediisocyanate
4) SBR1739 Latex
5) Nonghyup Shinan Sea Salt
6) Nitrogen adsorption 160~200m2/g CTAB adsorption 150~170m2/g and hydrogen ion index of 6~8 pH highly dispersible silica
7) X-50s (including Si69 50%)
8) The total content of PAHs (PolyCyclic Aromatic Hydocarbons) component is 3% by weight or less, and the kinematic viscosity is 95 (10% by weight of aromatic component in 210 μ softener, 40% by weight of naphthenic component and 40% by weight of paraffinic component) TDAE oil
9) ZnO
10) Stearic acid
11) Sulfur
12) CBS (N-cyclohexyl-2-benzothiazylsulfenamide)

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Example 2 Chamber temperature (℃) 23 10 33 23 23 23 Load (kg/tire) 400 400 400 500 400 400

[ Experimental example: measurement of physical properties ]

A tire with a broken block was placed on the mold structure, and the compositions according to Examples and Comparative Examples were cured to be integrated with the tire, and evaluation was performed based on Comparative Example 1. The results are shown in Tables 3 and 4 below.

Each evaluation method is as follows.

One) wear index

Using a Rambon wear tester, the wear resistance index of Comparative Examples 2 to 4 and Examples 1 and 2 compared to Comparative Example 1 is measured. The Rambon wear tester applies a load between the specimen and the grinding stone in a state in which a significantly larger abrasive wheel is in contact with the specimen, and simultaneously rotates the specimen axis and the grinding stone axis to induce wear due to slip caused by the difference in rotational speed between the two axes. It is a device that makes The higher the wear index, the better the wear resistance performance.

2) Retreading time index

Under the assumption of retreading, the retreading times of Comparative Example 1, Comparative Examples 2 to 4, and Examples 1 and 2 were measured.

3) Adhesion index with existing rubber

The durability test was operated to measure the degree of adhesion (whether or not the block was detached), and it was evaluated by driving the tire at 200 km/h for 2 hours.

Comparative Example 1 Example 1 Example 2 Wear Resistance Index 100 98 110 Retreading Time Index 100 5 10 Adhesion Index with Existing Rubber 100 98 99

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Example 2 Retreading Time Index 100 120 30 33 5 10 Wear Resistance Index 100 7 10 3 98 110

Referring to Tables 3 and 4, the tire repaired according to Examples 1 and 2 was lighter than the tire repaired according to Comparative Examples 1 to 4, while maintaining adhesion to the existing rubber at a level similar to that of Comparative Example 1. The reading time is significantly reduced, and compared to Comparative Examples 1 to 4, it is possible to secure the same level or improved properties.

Claims (12)

100 parts by weight of soft urethane; and
A rubber composition for repairing a tire tread comprising 50 to 100 parts by weight of a curing agent. The method of claim 1,
A rubber composition for repairing a tire tread further comprising styrene-butadiene latex. 3. The method of claim 2,
A rubber composition for repairing a tire tread further comprising salt. The method of claim 1,
The soft urethane is a rubber composition for repairing a tire tread having a hardness of Shore A50 to Shore A85. The method of claim 1,
The flexible urethane is a rubber composition for repairing a tire tread having a viscosity of 70 to 90 centipoise (cPS). A tire comprising the rubber composition for tire tread repair according to any one of claims 1 to 5. forming a mold structure in the chamber;
placing a worn tire on the mold structure;
A rubber composition for tire tread repair is injected between the mold structure and the tire,
The rubber composition for tire tread repair,
100 parts by weight of soft urethane and
A tire tread repair method comprising 50 to 100 parts by weight of a curing agent. 8. The method of claim 7,
The rubber composition for tire tread repair,
Styrene-butadiene latex (Styrene-butadiene latex) and salt (Salt) further comprising at least one selected from the group consisting of,
A tire tread repair method wherein the temperature in the chamber is 11 to 32 °C. 8. The method of claim 7,
The soft urethane is a tire tread repair method having a hardness of Shore A50 to Shore A85. 8. The method of claim 7,
The method for repairing a tire tread, wherein the flexible urethane has a viscosity of 70 to 90 cPS (centipoise). 8. The method of claim 7,
The tire is a tire tread repair method that supports a load of less than 500 kg per unit. 8. The method of claim 7,
The mold structure is a tire tread repair method formed using a 3D printing (Three Dimensional Printing) technology.