KR100444020B1 - Adhesion method for pneumatic tire - Google Patents

Abstract

In the present invention, two organic functional silane-based coupling agents having an amine-based functional group and a sulfan-based functional group for adhering the steel cord to a steel cord cutting surface having no brass layer, and thus, do not form an adhesive with rubber, are used for adhering the steel cord. The present invention relates to an adhesive method for mixing and coating a cement composition in which a rubber composition is dissolved in n-heptane. The steel cord cutting surface from which the brass layer is removed due to the characteristics of the silane coupling agent reacting with the rubber phase and the silane and the metal oxide layer. 100% adhesion to the rubber and rubber can suppress the occurrence of the initial crack which causes the belt to be separated, to prevent the separation between the belt stacks, and consequently to improve the durability of the tire as well as the brass layer and It is easy to use the adhesive because it does not inhibit the adhesion with the rubber.

Description

Bonding method of steel cord cutting surface of pneumatic tire {Adhesion method for pneumatic tire}

The present invention relates to a method for bonding the steel cord cutting surface of the pneumatic tire, and more specifically, between the steel cord cutting surface and the rubber of the pneumatic tire that does not form a bond to the rubber because there is no brass layer to cause an initial crack of the belt portion The present invention relates to an adhesion method that does not impair adhesion between the brass layer and rubber while improving adhesion.

Pneumatic tires are subjected to high loads and deformations of the vehicle while driving. In particular, since the belt portion of the tire supports most of such vehicle loads, it must withstand the deformation of harsh conditions compared to other parts of the tire. At this time, the stress of the belt part deformed is concentrated at the end part, and the concentration of this stress causes the crack generation from the belt end part, and gradually causes the growth, and ultimately the separation between the laminated belts.

In general, the adhesion of steel belts refers to the adhesion of brass plated steel to rubber. That is, it makes strong adhesion by inducing a Cu _x S bond between sulfur which exists in a rubber compound, and copper of a brass layer. By the way, the end portion of the belt portion is to be cut at a predetermined width and angle bar, and as a result, the cutting surface is present as a bare steel surface without a brass coating. Therefore, as described above, the belt edge portion, which is particularly stress concentrated, is such that no adhesion occurs between rubber and steel. This problem causes crack initiation.

Accordingly, the present inventors have developed a method of inducing adhesion between rubber and steel in consideration of the adhesion problem to the belt edge portion, and suppressing peeling of the belt portion based on such effects, and has previously filed a patent application. 2001-18849).

Here, the silane coupling agent is applied to both edge portions of the steel cord from which the brass layer has been removed to impart adhesion between the rubber and the steel, thereby suppressing the occurrence of initial cracks causing the belt to detach, thereby preventing the separation between the belt stacks. It provides a method for bonding the steel cord cutting surface of a pneumatic tire that can prevent it and, as a result, improve durability. Specifically, an alkoxy silyl end group between the bare steel surface and the rubber of the steel cord cutting surface of the pneumatic tire is provided. A silane adhesive layer having a was formed.

Here, as the silane adhesive having an alkoxy silyl end group, specifically, those having an amine functional group and sulfone functional groups were used in combination, and more specifically, bis- (γ-trimethoxysilylpropyl) amine ( Hereinafter, two silane compounds, called silane A) and bis- (3- [triethoxysilyl] -propyl) -tetrasulfane (hereinafter referred to as silane B), were used in combination.

However, when such an adhesive system is applied to both edge portions of the belt portion from which the brass layer is removed, the adhesive layer may be coated on the portion where the brass layer is not removed. In this case, a thin film is formed to inhibit adhesion between the brass and the rubber. Got to know. In other words, when the coating surface is not accurately coated only on the cut surface, the belt edge portion without the brass layer is provided with adhesive force, but the brass portion may act as a factor that inhibits adhesion.

Accordingly, the inventors of the present invention, while applying the adhesion to both edge portions of the tire steel cord, but does not hinder the adhesion between the brass layer and the rubber, the cement was dissolved in heptane with the belt coating composition with the silane coupling agent As a result of mixing and treating the composition, it was found that coating only to the edge portion of the steel cord exposed in the cutting process not only improves adhesion to rubber but also impairs adhesion between brass and rubber. The invention was completed.

Accordingly, an object of the present invention is that when the silane coupling agent is coated on the portion where the brass layer is removed, even if it is contaminated on the surface of the brass layer, the adhesive force at both edge portions of the belt portion can be improved without inhibiting the adhesive force with the rubber. To provide a way.

Such a bonding method of the present invention comprises a silane-based adhesive having the alkoxy silyl end group between the bare steel surface and the rubber of the steel cord cutting surface of the pneumatic tire; And cement prepared by dissolving the rubber composition for bonding the steel cord to 5 to 15 parts by weight based on 100 parts by weight of n-heptane; The adhesive layer is formed by mixing and applying in a weight ratio of 1: 1 to 1: 3.

1 is a photograph taken by the VMS image of the amount of the cord end cross-section and the rubber according to Experimental Example 3,

FIG. 2 is a photograph taken by VMS image of the amount of adhesion with rubber after coating and applying the same amount of silane coupling agent and cement mixed with silane A and silane B in a cord end section in accordance with Experimental Example 3 ,

FIG. 3 is a photograph taken by applying VMS image of the amount of adhesion with rubber after applying the same amount of silane coupling agent and cement mixed with silane A and silane B 1: 3 in the cord end section according to Experimental Example 3 .

The present invention will be described in more detail as follows.

In the present invention, the adhesive layer is formed on the cutting surfaces corresponding to both ends of the steel cord of the tire, and in addition, in order to prevent the adhesion between the brass layer and the rubber layer in consideration of contamination generated during the formation of the adhesive layer. The present invention relates to a method of mixing and coating a cement composition obtained by dissolving a rubber cord adhesive rubber composition of a tire in n-heptane together with a silane coupling agent between a bare steel surface and rubber.

The silane coupling agent used in the present invention has an alkoxy silyl end group, and more specifically, those having an amine functional group and those having a sulfan functional group are used in combination. More specifically, bis- (γ-trimethoxysilylpropyl) amine (hereinafter referred to as silane A) and bis- (3- [triethoxysilyl] -propyl) -tetrasulfane (hereinafter referred to as silane B) It is a combination of two silane compounds of.

These two organofunctional silanes each have a property of reacting with a rubbery phase, a silane, and a metal oxide layer. In the present invention, the two compounds are applied by applying such properties.

Applying such an organofunctional silane compound to a steel cord surface without a brass coating can impart an adhesive force between the steel cord surface and rubber, and the strength of the adhesive force is 83% or more than that of the brass layer. In particular, as a result of evaluating the cross section to be bonded to the rubber with a very small area such as the edge part, the rubber adhesion amount was 0%, whereas the adhesion was 100%.

The mixing ratio of the two organic functional silane compounds suitable for exhibiting such an effect is when silane B is a weight ratio of 1: 1 to 5 with respect to silane A.

On the other hand, the cement composition to be mixed with such a silane coupling agent is obtained by dissolving a rubber composition for bonding the steel cord of a commonly used tire to 5 to 15 parts by weight with respect to 100 parts by weight of n-heptane, at this time The rubber composition is about 6 to 9 parts by weight of insoluble sulfur with respect to 100 parts by weight of natural rubber, and refers to a composition having a high content of sulfur involved in adhesion.

The steel cord adhesive rubber composition is dissolved in 5 parts by weight to 15 parts by weight of n-heptane. If dissolved in n-heptane, the rubber composition for adhesive cord is out of the range with respect to 100 parts by weight of n-heptane. When dissolved, there is a problem that some remain as solids.

When the cement composition obtained by the above method is mixed with the silane coupling agent, the mixing ratio is preferably 1: 1 to 1: 3 with respect to the silane coupling agent. If the amount of the cement composition is mixed with the silane coupling agent, Outside the above range, a problem may occur that is lower than the optimum adhesive strength.

In this way, when the silane coupling agent and the cement composition are mixed and applied to the bare steel surface from which the brass layer has been removed, the amount is preferably applied to a thickness of about several μm.

As described above, when a separate adhesive layer is formed between both edge portions of the steel cord from which the non-bonding brass layer is removed and the rubber layer, it is possible to suppress the occurrence of an initial crack that causes the belt to detach. By suppressing crack generation, it is possible to prevent separation between the belt stacks, and ultimately improve the durability of the tire. In addition, even if a part of the adhesive is applied to the brass layer, the adhesion between the brass layer and the rubber does not inhibit, so there is no need to pay particular attention to coating only on both edge portions.

Hereinafter, the present invention will be described in detail with reference to the following Examples, but the present invention is not limited by the Examples. In the following examples, Example 1 is a result of coating the cement composition according to the present invention on the surface of the steel cord from which the brass layer is removed to give an adhesive force, and Examples 2 to 3 test the case coated on the brass. .

Examples 1-3 and Comparative Examples 1-4

The brass layer was used after removing the brass layer from the 3 + 9 + 15 (0.22) 1 W cord used in the tire to test the adhesion using the steel cord without the brass layer. A peeling solution was prepared and used to remove the brass layer. The peeling solution was prepared by mixing 300 ml of NH ₄ OH and 25 g of CCl ₃ COOH in 500 ml of distilled water.

The bare steel, from which the brass layer was removed, was immersed and washed in hexane and methanol, and then washed with acetone and dried with hot air.

General rubber cord adhesive rubber was used as the rubber.

Meanwhile, as the adhesive, silane A, silane B, and a silane mixture prepared by mixing them in a weight ratio of 1: 1 to 1: 3, respectively, and a rubber composition for adhering steel cords were dissolved in 10 parts by weight of 100 parts by weight of n-heptane. A cement system prepared by mixing the prepared cement in a 50:50 weight ratio was prepared in a vial, and then the previously prepared soak cord was used by dip coating.

Coated steel cords were immediately fabricated and vulcanized into rubber pull-out samples and edge-adhesion specimens with rubber stock without special drying.

Basically, the test was performed according to the ASTM D 2229-80 method for the untreated group of brass flattened steel and rubber and the bare steel and each cement composition applied.

The treatment methods of Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 1 below, and the results of measuring the adhesive strength are shown in Table 2 below.

Example Comparative Example One 2 3 One 2 3 4 Silane coupling agent (mixing ratio) Silane A One One One - - One - Silane B 3 One 3 - - 3 - Mixing ratio (weight ratio) of cement and silane coupling agent cement 50 50 50 - - 0 100 Silane Coupling Agent 50 50 50 - - 100 0 Code surface condition Soaked (without brass) Brass layer Soaked (without brass) Brass layer

Example Comparative Example One 2 3 One 2 3 4 Adhesive force (kgf / in) 92 118 123 27 121 98 119 Adhesion amount (%) 80 100 100 0 100 90 100

From the results in Table 2 above, the adhesion to the brass flat steel cord (Comparative Example 2) basically showed an adhesion amount of 100% at 121 kgf, while in the bare steel (Comparative Example 1) it had an adhesion amount of 0% at 27 kgf. That is, it can be seen that the adhesion between the steel cord from which the brass layer is removed and the rubber is not performed.

By the way, when the surface of the system prepared by mixing 1: 3 mixture of silane A and B and cement at 50:50 (Example 1) showed an adhesive strength of 92 kgf / in and an adhesion amount of 80%. That is, through the effective mechanism of adhesion by the functional group of the mixed silane mixture showed an adhesion of up to 76% compared to the brass cord. In addition, in the case of Examples 2 and 3, when the brass was not removed, the present system was applied to exhibit an adhesive strength equal to or higher than that of Comparative Example 2. By the way, when only the silane coupling agent is coated on the brass layer (Comparative Example 3), it can be seen that the adhesive force is reduced. This shows that a problem may occur if the edges, which are cut surfaces, are not accurately coated and diffused in the brass layer. Comparative Example 4 confirms the effect of the simple cement composition, it can be seen that the problem does not occur when the adhesion to the brass does not occur.

Experimental Example 1

In Experimental Example 1, a system prepared by mixing a 1: 1 mixture of silanes A and B and cement in a mixture of Table 1 at 50:50 (Example 2) was coated on a general brass flat cord to evaluate a low adhesive strength. As a result, the results showed the same level of adhesion as in Comparative Example 2 and the adhesion amount showed a value of 100%. That is, it has been shown that the system of the present invention forms adhesion to the edge portion and at the same time does not degrade the original adhesion even when contaminated with the brass layer.

Experimental Example 2

In Experimental Example 2, a system (Example 1) prepared by mixing a 1: 3 mixture of silanes A and B and cement in a mixture of Table 1 at 50:50 was tested in the same manner as in Experiment 1. The adhesion level showed rather strong adhesion when the adhesive of the present invention was coated. In addition, the adhesion amount showed 100%.

Experimental Example 3

In Experiment 3, the 1: 1 and 1: 3 mixtures of silanes A and B in the mixture of Table 1 were coated and tested at the edge of the steel cord from which the brass layer was removed. That is, since the cross-sectional area of the edge portion is relatively small, in order to quantitatively evaluate the practical adhesion degree in this portion, the amount of rubber adhered to the edge portion (with a soaked steel state as the cutting surface) with or without silane coupling agent treatment was measured. Taken and compared. In particular, for the edge part, the cord was placed up to the middle part of the rubber specimen, and after vulcanization and drawing, images were taken and compared.

In particular, for the edge portion, the cord was placed up to the middle portion of the rubber specimen, followed by vulcanization and drawing, and images were taken and compared.

Both 1: 1 and 1: 3 mixtures of silanes A and B showed 100% adhesion and 0% when no silane coupling agent was used. The results are shown in Table 3 below.

Silane A: B 1: 1 1: 3 - Cement: Silane Coupling Agent 50:50 50:50 - Cross section adhesion amount (%) 100 100 0

In addition, the photograph which photographed the rubber adhesion amount is as FIG. FIG. 1 is a photograph of rubber adhesion when no silane coupling agent is used, FIG. 2 is a photograph of rubber adhesion using a 1: 1 mixture of silane A and silane B, and FIG. 3 is a 1: 3 of silane A and silane B. It is a photograph of rubber adhesion amount using a mixture.

As described in detail above, according to the present invention, two organic functional silane coupling agents having an amine functional group and a sulfan functional group are used, and a conventional rubber cord adhesive rubber composition is dissolved in n-heptane. When the obtained cement composition is mixed and applied to the steel cord cutting surface from which the brass layer has been removed and adhered to the steel cord rubber, in general, there is no brass layer so that adhesion with the rubber is not formed, but due to the action of the silane coupling agent 100 As it can be attached, it is possible to suppress the occurrence of the initial crack which causes the belt to be separated, to prevent the separation between the belt stacks, and to improve the durability of the tire, and even to apply the brass layer to the steel cord rubber It is easy to use because it does not inhibit the adhesive force with.

Claims (2)

(Correction) A bonding method in which a silane adhesive layer having an alkoxy silyl end group is formed between a soaked steel surface and rubber of a steel cord cutting surface of a pneumatic tire, Formation of the adhesive layer, A silane adhesive having the alkoxy silyl end group and Pneumatic tire, characterized in that is carried out by mixing and applying a cement prepared by dissolving the rubber composition for bonding the steel cord to 5 to 15 parts by weight with respect to 100 parts by weight of n-heptane in a weight ratio of 1: 1 to 1: 3 Method for cutting steel cord cutting surface The method for adhering the steel cord cutting surface of a pneumatic tire according to claim 1, wherein the rubber cord bonding rubber composition contains insoluble sulfur in an amount of about 6 to 9 parts by weight based on 100 parts by weight of natural rubber.