KR102024370B1 - Tire steel belt, method of manufacturing the same and tire comprising thereof - Google Patents

Abstract

The present invention relates to a steel cord, a topping rubber and a coating layer coated with a mixed oil, wherein the mixed oil includes a naphthenic oil and a sorbitan fatty acid. The adhesion can be enhanced to prevent the separation of the steel belt and improve the durability of the tire.

Description

TIRE STEEL BELT, METHOD OF MANUFACTURING THE SAME AND TIRE COMPRISING THEREOF

The present invention relates to a tire steel belt, a manufacturing method thereof, and a tire including the same, further including a coating layer on the cross section of the steel belt, thereby improving the adhesion and durability of the steel belt.

A general vehicle tire is composed of a tread part directly contacting the road surface, a sidewall part installed at both ends of the tread part to absorb the impact from the road surface, and a bead part installed at the bottom of the sidewall part and mounted on the rim of the vehicle. Each part is made of semi-finished product by each process, and after forming process, it is formed into green tires and manufactured by tire after vulcanization process.

The tread part is a part in direct contact with the road surface, which has good abrasion resistance and cut resistance, as well as low heat generation, and requires physical properties of sufficient shock absorption. Accordingly, the belt layer is provided at the bottom of the tread portion to increase the strength of the tread portion, and prevents the shock received from the tread portion and the cracks generated in the tread from being transmitted to the carcass.

In order to perform this role, the conventional belt layer is a steel cord is constantly arranged and a rubber topping is made thereon, the belt is cut to a certain size and angle according to the tire specifications or specifications, and a plurality of sheets of steel It is made of a belt.

In general, the steel belt is a component that has a great influence on the grip force, handling performance and ride comfort, along with the role of protecting the carcass, which is a skeleton, in the tire.

However, the steel belt has a problem in that adhesive strength with rubber, which is a main material of a tire, is weak due to the characteristics of the steel cord material. Conventional steel belts are used with brass plating to improve adhesion. However, when the rolled steel belts are cut to apply to tires, unplated parts are exposed on the cut section, and replating only the exposed parts is required. There has been a problem that is impossible.

Therefore, in order to improve the adhesion of the steel cord and prevent corrosion, the development of a technology that complements the exposed cross section of the steel belt is required.

It is an object of the present invention to provide a tire steel belt with improved adhesion and corrosion resistance.

Still another object of the present invention is to provide a method for manufacturing the tire steel belt and a tire manufactured by the same.

The present invention includes a coating layer coated with a steel cord, rubber for topping and mixed oil, wherein the mixed oil includes naphthenic oil and sorbitan fatty acid.

The mixed oil may be a mixture weight ratio of naphthene oil and sorbitan fatty acid 90:10 to 70:30.

The mixed oil may have a specific gravity of 0.840 to 0.863 (20 ° C), a kinematic viscosity of 30 to 45 cSt (40 ° C) or 3 to 7 cSt (100 ° C), and an ester index of 40 to 60.

The sorbitan fatty acid may be any one selected from the group consisting of sorbitan monooleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, and combinations thereof.

The mixed oil coating amount may be 1.0 to 7.5 g / ㎠.

The topping rubber is 100 parts by weight of natural rubber, 50 to 80 parts by weight of carbon black, 1 to 3 parts by weight of resorcinol resin, 3 to 7 parts by weight of vulcanizing agent, 0.3 to 0.7 parts by weight of vulcanization accelerator, 5 to 10 parts of zinc oxide. It may be to include parts by weight, 0.1 to 0.5 parts by weight of stearic acid, and 1 to 3 parts by weight of a softener.

The steel cord may be plated with brass.

The coating layer may be applied to the cross section of the steel cord exposed during the cutting of the steel belt semi-finished product to which the topping rubber on both sides of the steel cord.

The present invention is also a steel cord arrangement step, placing the rubber for topping on both sides of the steel cord and rolling to produce a steel belt semi-finished product, cutting the rolled semi-finished product, and the steel cord exposed during the cutting Applying a mixed oil to the cross section of the to form a coating layer, wherein the mixed oil provides a method for producing a tire steel belt comprising naphthene oil and sorbitan fatty acid.

The steel cord may be arranged as a first steel cord layer arranged in a circumferential direction (0 °) from 15 to 70 ° and a second steel cord layer arranged in a symmetrical direction with the first steel cord layer. .

The present invention also provides a tire in which the steel belt is interposed between the carcass and the tread portion.

The present invention can provide a tire steel belt with improved adhesion and corrosion resistance.

The present invention can also provide a tire comprising the tire steel belt.

The present invention can also improve the durability of the tire using the supplemented steel belt.

1 is a half sectional view of a tire according to an embodiment of the present invention.
2 is a view showing a cross section of the tire steel belt according to an embodiment of the present invention.
Figure 3 is a graph showing the adhesion test results of the steel belt cross section according to an experimental example of the present invention.

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

According to an embodiment of the present invention, the tire steel belt according to the present invention includes a coating layer coated with a steel cord, rubber for topping and mixed oil. The mixed oil is characterized in that it comprises naphthenic oil and sorbitan fatty acid.

1 is a half sectional view of the tire. Hereinafter, the tire will be described with reference to FIG. 1.

Referring to FIG. 1, the tire includes a tread portion 1, a sidewall portion 2, and a bead portion 3. A carcass layer 4 is constructed between the left and right pairs of bead portions 3, and both ends of the tire width direction of the carcass layer 4 extend from the inside of the tire to the outside of the bead core 5, respectively. Wind up In the tread portion 1, a steel belt layer 6 is disposed outside the carcass layer 4, and an inner liner 7 is disposed inside the carcass layer 4.

The steel belt layer 6 will be described with reference to FIG. 2. FIG. 2 is a cross-sectional view of the steel belt layer 6, which is composed of a cord 6a and a rubber for topping 6b.

Steel belt according to the present invention is a steel cord (6a) arranging step (S1), the step of placing the rubber topping rubber (6b) on both sides of the steel cord (6a) step to produce a steel belt semi-finished product (S2) To cut the rolled semi-finished product (S3), by applying a mixed oil to the cross section of the steel cord (6a) exposed during the cutting to form a coating layer (S4).

Hereinafter, the steel belt will be described in the order of its manufacturing method.

S1. Steel Cord Arrangement Step

The steel cord 6a may be plated with brass (Brass, Cu / Zn) at a level of 200 to 300 nm in carbon steel having a carbon content of 0.70 to 0.95 wt%.

The steel cord 6a may be arranged in an oblique line of 15 to 70 ° with respect to the circumferential direction (0 °), or may further include a second steel cord layer arranged in a direction symmetrical to the direction. .

S2. Manufacturing the steel belt semi-finished product by placing and rolling the rubber for topping on both sides of the steel cord

The topping rubber 6b forms a skeleton of the tire together with the cord 6a and functions to support internal pressure. The topping rubber 6b has good adhesion to the cord 6a and should not be aging even for a long run.

The topping rubber is 100 parts by weight of natural rubber, 50 to 80 parts by weight of carbon black, 1 to 3 parts by weight of resorcinol resin, 3 to 7 parts by weight of vulcanizing agent, 0.3 to 0.7 parts by weight of vulcanization accelerator, 5 to 10 parts of zinc oxide. It may be to include parts by weight, 0.1 to 0.5 parts by weight of stearic acid, and 1 to 3 parts by weight of a softener.

The natural rubber may be used as long as it is known as a general natural rubber, and the origin and the like are not limited. The natural rubber contains cis-1,4-polyisoprene as a main agent, but may also include trans-1,4-polyisoprene depending on the required properties. Therefore, the natural rubber includes, in addition to the natural rubber containing cis-1,4-polyisoprene as a main agent, for example, a natural containing trans-1,4-isoprene as a main agent such as a balata, which is a kind of rubber of South American sapotagua. Rubber may also be included.

As said carbon black, it is preferable that nitrogen adsorption amount is 130-150m <2> / g, and DBP value 120-130cc / 100g.

The topping rubber 6b may further include a resorcinol resin to improve adhesion to the cord 6a. The resorcinol resin may be specifically resorcinol formaldehyde latex (RFL). The resorcinol formaldehyde latex is synthesized by reacting resorcinol and formaldehyde under alkaline conditions and then adding latex, wherein the resorcinol formaldehyde resin and latex are 1: 4.9 to 1: 5.2 parts by weight is mixed Can be.

The resorcinol formaldehyde latex can form a three-dimensional network structure to provide desirable heat and fatigue resistance to the adhesive itself to improve the adhesion to the cord (6a) to be bonded.

As the vulcanizing agent, metal oxides such as sulfur-based vulcanizing agents, organic peroxides, resin vulcanizing agents, and magnesium oxide may be used.

The sulfur-based vulcanizing agents include inorganic vulcanizing agents such as powdered sulfur (S), insoluble sulfur (S), precipitated sulfur (S) and colloidal sulfur, tetramethylthiuram disulfide (TMTD) and tetraethyl. Organic vulcanizing agents such as tetraethyltriuram disulfide (TETD) and dithiodimorpholine may be used, and sulfur containing naphthenic oil may be used.

Specifically, as a sulfur vulcanizing agent, a vulcanizing agent for producing elemental sulfur or sulfur, for example, amine disulfide, polymer sulfur, and the like can be used.

The vulcanizing agent is preferably included in 3 to 7 parts by weight based on 100 parts by weight of the raw material rubber (natural rubber) in that the raw material rubber is less sensitive to heat and chemically stable.

The vulcanization accelerator refers to an accelerator that promotes the rate of vulcanization or promotes delay in the initial vulcanization stage.

The vulcanization accelerators include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine, aldehyde-ammonia, imidazoline, xanthate and their Any one selected from the group consisting of a combination can be used.

Examples of the thiazole vulcanization accelerators 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 thiazole compound selected from the group consisting of ethyl 4-morpholinothio) benzothiazole and combinations thereof can be used.

The vulcanization accelerator may be included in an amount of 0.3 to 0.7 parts by weight based on 100 parts by weight of the raw material rubber in order to maximize productivity and rubber properties by promoting the vulcanization rate.

The vulcanization accelerator is a compounding agent used in combination with the vulcanization accelerator to complete its promoting effect. Any one selected from the group consisting of inorganic vulcanization accelerators, organic vulcanization accelerators and combinations thereof can be used. .

The inorganic vulcanization accelerator may be any one selected from the group consisting of zinc oxide (ZnO), zinc carbonate, magnesium oxide (MgO), lead oxide, potassium hydroxide, and combinations thereof. 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 either one.

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

When using the zinc oxide and the stearic acid together may be used in 5 to 10 parts by weight and 0.1 to 0.5 parts by weight with respect to 100 parts by weight of the raw material rubber, respectively, to serve as a suitable vulcanization accelerator. When the content of zinc oxide and the stearic acid is less than the above range, the vulcanization rate may be low, and productivity may be lowered. When the zinc oxide and the stearic acid are below the above range, a scorch phenomenon may occur and physical properties may be reduced.

The softener is added to the rubber composition to impart plasticity to the rubber to facilitate processing or to lower the hardness of the vulcanized rubber, and refers to oils and other materials used in rubber compounding or rubber production. The softener may be any one selected from the group consisting of petroleum oil, vegetable oil and combinations thereof, but the present invention is not limited thereto.

The petroleum oil may be any one selected from the group consisting of paraffinic oil, naphthenic oil, aromatic oil, and combinations thereof. Typical examples of the aromatic oils include A-2 and A-3 of Michang Oil Co., Ltd.

The softener is preferably contained in 1 to 3 parts by weight based on 100 parts by weight of the raw material rubber.

The semi-finished steel belt 6 can be manufactured by rolling the topping rubber 6b including the above structure on the upper and lower portions of the steel cord 6a arranged in S1 and then rolling.

S3. Cutting the rolled semifinished product

Semi-finished products of rolled tire steel belts can be cut and used for the application. When cutting, the uncoated steel cord 6a cross section is exposed. The exposed cross section has no adhesive force and thus is easily separated from the rubber material, thereby degrading durability.

In particular, the exposed cross section is located at the shoulder of the tire, causing separation of the steel belt layer 6 from the tread or carcass layer. Usually the start of separation of the steel belt layer 6 begins at the interface of the steel belt layer 6. When the two layers of steel belt layer 6 are included, the first steel belt layer and the second steel belt layer 6 have the same angle but are stacked in opposite directions. Relatively much movement occurs at both ends of the layer and the second steel belt layer 6. Many movements of the ends of the steel belt layer 6 may cause separation of the steel belt layer 6.

Therefore, in order to solve such a problem, it is necessary to increase the adhesive strength of the exposed cross section. However, in the tire cutting process, it is practically impossible to apply a plating bath and an electric power supply to all cutting facilities to plate the cut surface of the rubber-coated steel cord 6a semifinished product. It is also not possible with current technology to plate only the cross section of the inner steel cord 6a that is not plated in rubber-coated semi-finished products.

The present invention can solve the problem by forming a coating layer in the following way.

S4. Step of forming a coating layer by applying a mixed oil to the cross section of the steel cord exposed when cutting

The coating layer is formed by applying a mixed oil to the cross section of the steel cord 6a exposed at the time of cutting the steel belt semi-finished product to which the topping rubber is rolled on both sides of the steel cord 6a.

The mixed oil may include naphthenic oil and sorbitan fatty acid.

The naphthene oil refers to a base oil having a viscosity index of 85 or less and having at least 30% of the carbon bonds in the analysis according to ASTM D-2140 having a naphthenic composition. Preferably the naphthene oil may have a naphthene content of 10 to 50% by weight.

The sorbitan fatty acid (Sorbitan Fatty Acid) means a nonionic surfactant. Specifically, the sorbitan fatty acid may be any one selected from the group consisting of sorbitan monooleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, and combinations thereof.

The mixed oil may be a mixed weight ratio of naphthenic oil and sorbitan fatty acid 90:10 to 70:30.

The mixed oil is effective in preventing corrosion and enhancing adhesive properties. When the mixed amount exceeds the above range, the corrosion resistance and the adhesive property may decrease, and the mixed amount may be less than the above range. In this case, there is a fear that the adhesive strength of the finally obtained composition is reduced to achieve the object to be obtained in the present invention.

The mixed oil has a specific gravity of 0.840 to 0.863 (20 ° C), a kinematic viscosity of 30 to 45 cSt (Centistokes) at 40 ° C, a kinematic viscosity of 3 to 7 cSt at 100 ° C, and an ester index of 40 to 60 It may be.

The mixed oil applied to the cross section of the tire steel cord 6a exhibits an excellent aging adhesive force in a wide range of areas, so that the amount of oil applied is maintained in the range of 1.0 to 7.5 g / cm 2, preferably 1.0 to 7.5 g / cm 2. It is preferable to apply. When the amount of oil applied is less than 1.0 g / cm 2, the application effect of oil is insufficient. On the contrary, when the amount exceeds 7.5 g / cm 2, the application effect (adhesive effect) of oil tends to decrease rather than cutting. It is undesirable because the process causes contamination of the conveyor belt of the cutting equipment and the bobbin winding the cutting material.

In addition, the mixed oil according to the present invention does not need to be diluted and used in a separate concentration, and there is an advantage that the application can be easily performed because it does not have to go through a drying process at a high temperature after application.

The application of the mixed oil proceeds with the steel cord 6a embedded in the rubber. Using a brush can be applied directly to the cut surface of the steel cord (6a) or by applying a predetermined amount to the cutting knife (cutting knife) to be applied to the cut surface of the steel cord (6a) when cutting.

The tire according to another embodiment of the present invention includes the tire steel belt 6.

Since the method of manufacturing the tire steel belt 6 can be applied to any method conventionally used for the production of tires, detailed description thereof will be omitted.

The tire may be, but is not limited to, a tire for a bus truck (BTR), a tire for a small truck (LTR), or a tire for a passenger car.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Preparation Example 1: Steel Belt Manufacturing

Naphthene oil and sorbitan were mixed to prepare a mixed oil. In order to reproduce the cut surface of the steel cord, an unplated steel cord having a 3 (0.20) + 6 (0.35) structure was prepared and the mixed oil prepared above was applied. The coating amount is shown in Table 1 below.

division Mixed oil application amount (g / ㎠) Example 1 0.5 Example 2 1.5 Example 3 3.5 Example 4 7.5 Example 5 15.5 Comparative Example 1 0

Semi-finished steel belts were formed by rolling at a pressure of 103 atm and 150 ° C. for 30 minutes in a state where the rubber sheet prepared in the composition of Table 2 was attached to both sides of the steel cord coated with the mixed oil.

Item Parts by weight caoutchouc 100 Carbon black 60 Zinc oxide 7 sulfur 5 Stearic acid 0.3 Benzothiazole 0.5  Aromatic oils 2.0 Resorcinol resin 1.5

Experimental Example: Measurement of Physical Properties of Prepared Rubber Composition

The adhesion test of the steel belts prepared in Examples and Comparative Examples was performed according to ASTM D-2229, the results of which are shown in Table 3 below.

division Mixed oil application amount (g / ㎠) Initial Adhesion (kgf / in) Aging Adhesion (kgf / in) Heat aging Water aging Brine aging   Example 1   0.5 80 50 55 68  Example 2  1.5 83 67 65 71  Example 3  3.5 82 68 66 73  Example 4  7.5 85 65 63 69  Example 5  15.5 50 60 62 68

Initial adhesive strength was shown by measuring the adhesive force between the steel belt rubber (topping rubber) and the steel cord while pulling out the steel cord from the steel belt in the tensile tester prepared in Preparation Example 2.

The aging adhesive strength was measured in the same manner as the initial adhesive strength measurement after the steel belt specimen was stored for 3 weeks at 100 ℃ in order to determine the thermal aging adhesive strength in a high temperature atmosphere.

In addition, another test piece was stored for 3 weeks in an atmosphere of 96% relative humidity at 70 ° C. in order to determine the water aging adhesive strength in a moisture atmosphere, and then the adhesive strength was measured in the same manner as in the initial adhesive force measuring method. In order to determine the salt aging adhesive strength was measured for 3 weeks in 20% NaCl aqueous solution and then the adhesive strength was measured by the same measurement method as the initial adhesive strength measurement method.

Referring to Table 3, in the case of the specimen of the present invention, the initial adhesive strength is similar to that of the conventional cross-section untreated product (comparative example), but the aging adhesiveness (thermal) over time in an extreme aging atmosphere Aging, water aging, brine aging) showed superior results compared to conventional products.

As described above, the steel belt coated on the cutting surface of the mixed oil containing naphthene oil and sorbitan fatty acid according to the present invention, the composite oil of the tire while improving the tear physical properties of the rubber when the composite with the tire rubber The effect of maintaining the aging adhesive strength under extreme conditions by driving is expected. Therefore, the steel cord coated on the cut surface of the mixed oil has an advantage of exhibiting high aging adhesiveness for rubber of all compositions, and can be used for reinforcing various rubber products including belts, straps and hoses in addition to tire reinforcement. It is expected.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1: tread section
2: sidewall
3: bead part
4: carcass layer
5: bead core
6: steel belt layer
7: innerliner

Claims (11)

Steel Cord,
Topping rubber and
A mixed oil coated coating layer,
The coating layer is applied to the cross section of the steel cord exposed during the cutting of the steel belt semi-finished product to which the topping rubber is rolled on both sides of the steel cord,
The mixed oil is to include naphthenic oil and sorbitan fatty acid
Tire steel belt. The method of claim 1,
The mixed oil is a tire steel belt is a mixed weight ratio of naphthene oil and sorbitan fatty acid 90:10 to 70:30. The method of claim 1,
The mixed oil has a specific gravity of 0.840 to 0.863 (20 ° C.), a kinematic viscosity of 30 to 45 cSt (40 ° C.) or 3 to 7 cSt (100 ° C.), and an ester index of 40 to 60. belt. The method of claim 1,
The sorbitan fatty acid is a tire steel belt is any one selected from the group consisting of sorbitan monooleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate and combinations thereof. The method of claim 1,
The mixed oil coating amount is 1.0 to 7.5 g / ㎠ tire steel belt. The method of claim 1,
The topping rubber is 100 parts by weight of natural rubber, 50 to 80 parts by weight of carbon black, 1 to 3 parts by weight of resorcinol resin, 3 to 7 parts by weight of vulcanizing agent, 0.3 to 0.7 parts by weight of vulcanization accelerator, 5 to 10 parts of zinc oxide. A tire steel belt comprising 1 part by weight, 0.1 to 0.5 parts by weight of stearic acid, and 1 to 3 parts by weight of a softener. The method of claim 1,
The steel cord is a tire steel belt is brass plated. delete Steel cord arrangement step,
Manufacturing a steel belt semi-finished product by placing and rolling the rubber for topping on both sides of the steel cord;
Cutting the rolled semifinished product, and
And applying a mixed oil to the cross section of the steel cord exposed during the cutting to form a coating layer.
The mixed oil is to include naphthenic oil and sorbitan fatty acid
Tire steel belt manufacturing method. The method of claim 9,
The steel cord is a tire arranged with a first steel cord layer arranged in a circumferential direction (0 °) in a range of 15 to 70 ° and a second steel cord layer arranged in a symmetrical direction with the first steel cord layer. Steel belt manufacturing method. A tire in which the steel belt according to any one of claims 1 to 7 is interposed between the carcass and the tread portion.

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