KR20190083186A - Tire steel belt, method of manufacturing the same and tire comprising thereof - Google Patents

Abstract

The present invention relates to a tire steel belt having a steel cord, rubber for topping, and a coating layer applied with mixed oil, wherein the mixed oil comprises naphthene oil and sorbitan fatty acids. Therefore, a cross section is reinforced, and a bonding force of the cross section is increased to prevent the steel belt from being separated, and improve durability of a tire.

Description

TECHNICAL FIELD [0001] The present invention relates to a tire steel belt, a method of manufacturing the same, and a tire including the same. BACKGROUND OF THE INVENTION [0001]

The present invention relates to a tire steel belt which further includes a coating layer on an end face of a steel belt to improve the adhesion and durability of the steel belt, a method of manufacturing the same, and a tire including the same.

A general vehicle tire comprises a tread portion that is in direct contact with the road surface, a side wall portion that is provided at both ends of the tread portion to absorb impact from the road surface, and a bead portion that is installed at the bottom of the side wall portion, Each part to be composed is finished with semi-finished products by each process, and is molded into a green tire while undergoing molding process, followed by vulcanization to manufacture tire.

The tread portion is a portion directly contacting with the road surface, which must have good abrasion resistance and cut resistance, and must have a low heat generation and a sufficient physical property of a shock absorbing force. Accordingly, a belt layer is provided at the bottom of the tread portion to increase the strength of the tread portion, and to prevent the impact received from the tread portion and cracks or the like generated in the tread from being transmitted to the carcass.

In order to perform such a role, a conventional belt layer is formed by regularly arranging steel cords and rubber topping, and these belts are cut at a predetermined size and angle according to the size or specification of the tire, Belt.

In general, steel belts are a component that greatly affects the gripping force, handling performance and ride comfort, as well as protecting the carcass, which is called the skeleton, in the tire.

However, the steel belt has a problem in that the adhesive strength to rubber, which is the main material of the tire, is weak due to the characteristics of the steel cord material. Existing steel belts are used with brass plating to improve adhesion, but when the rolled steel belt is cut to apply to the tire, the uncoated portion is exposed on the cut surface and only the exposed portion is re-plated There has been a problem that is impossible.

Therefore, it is necessary to develop a technique for improving the adhesion of the steel cord and complementing the exposed cross section of the steel belt in order to prevent corrosion.

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

It is still another object of the present invention to provide a method of manufacturing the tire steel belt and a tire manufactured using the same.

The present invention provides a tire steel belt comprising a steel cord, a topping rubber and a coating layer coated with a mixed oil, wherein the blended oil comprises naphthenic oil and sorbitan fatty acid.

The mixed oil may have a mixing weight ratio of naphthenic oil and sorbitan fatty acid of 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 application amount may be 1.0 to 7.5 g / cm 2.

Wherein the topping rubber comprises 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, 0.1 to 0.5 parts by weight of stearic acid, and 1 to 3 parts by weight of a softening agent.

The steel cord may be brass plated.

The coating layer may be applied to a cross section of a steel cord exposed at the time of cutting a steel belt semi-finished product in which a rubber for topping is rolled on both sides of a steel cord.

The present invention also relates to a method of manufacturing a steel cord comprising the steps of arranging a steel cord, placing the rubber for topping on both sides of the steel cord and rolling the same to manufacture a steel belt semi-finished product, cutting the rolled semi-finished product, Wherein the mixed oil comprises naphthenic oil and sorbitan fatty acid. The present invention also provides a method for manufacturing a tire steel belt, comprising the steps of:

The steel cord may be arranged in a first steel cord layer arranged at 15 to 70 degrees with respect to the circumferential direction (0 DEG) and a second steel cord layer arranged in a direction symmetrical to the first steel cord layer .

The present invention also provides a tire wherein 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 by using the above-mentioned reinforced steel belt.

1 is a half sectional view of a tire according to an embodiment of the present invention.
2 is a cross-sectional view of a tire steel belt according to an embodiment of the present invention.
FIG. 3 is a graph showing an adhesive force test result of a steel belt section according to an experimental example of the present invention.

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

According to one embodiment of the present invention, a tire steel belt according to the present invention comprises a steel cord, a rubber for topping and a coating layer coated with a mixed oil. The mixed oil is characterized by containing 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.

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 laid between the left and right pair of bead portions 3 and both end portions of the carcass layer 4 in the tire width direction are respectively located on the periphery of the bead core 5 from the inside to the outside of the tire Climb up. A steel belt layer 6 is provided on the outer side of the carcass layer 4 in the tread portion 1 and an inner liner 7 is disposed on the inside of the carcass layer 4.

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

The steel belt according to the present invention includes a step of arranging a steel cord 6a, a step S2 of placing a rubber for topping 6b on both sides of the steel cord 6a and rolling the same, , Cutting the rolled semi-finished product (S3), and coating a mixed oil on an end face of the steel cord 6a exposed at the time of cutting to form a coating layer (S4).

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

S1. Steel Code Layout Steps

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

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

S2. Placing the rubber for topping on both sides of the steel cord and then rolling to manufacture a semi-finished steel belt product

The topping rubber 6b forms a skeleton of the tire together with the cord 6a and functions to support the internal pressure. The topping rubber 6b should have good adhesion with the cord 6a and should not be aged even when traveling for a long time.

Wherein the topping rubber comprises 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, 0.1 to 0.5 parts by weight of stearic acid, and 1 to 3 parts by weight of a softening agent.

The natural rubber may be any known natural rubber, and the origin of the natural rubber is not limited. The natural rubber includes cis-1,4-polyisoprene as a main component, but may also include trans-1,4-polyisoprene depending on required characteristics. Therefore, in addition to natural rubber containing cis-1,4-polyisoprene as a main component, natural rubber including trans-1,4-isoprene as a main component, such as balata, Rubber may also be included.

The carbon black preferably has a nitrogen adsorption amount of 130 to 150 m 2 / g and a DBP value of 120 to 130 cc / 100 g.

The topping rubber may further include a resorcinol resin to improve the adhesive strength with (6b) the cord 6a. The resorcinol resin may specifically be resorcinol formaldehyde latex (RFL). The resorcinol formaldehyde latex is synthesized by reacting resorcinol with formaldehyde under alkaline conditions and then adding latex. The resorcinol formaldehyde resin and latex are mixed in a ratio of 1: 4.9 to 1: 5.2 .

The resorcinol formaldehyde latex forms a three-dimensional network structure to provide desirable heat and fatigue resistance to the adhesive itself, thereby improving the adhesion with the cord 6a to be bonded.

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

The sulfur vulcanizing agent is an inorganic vulcanizing agent such as powder sulfur (S), insoluble sulfur (S), precipitated sulfur (S), colloid sulfur, etc., tetramethylthiuram disulfide (TMTD) Organic vulcanizing agents such as tetraethyltriuram disulfide (TETD) and dithiodimorpholine can be used, and sulfur containing naphthenic oil can be used.

Examples of the sulfur vulcanizing agent include a vulcanizing agent which produces elemental sulfur or sulfur, for example, amine disulfide, polymer sulfur and the like.

It is preferable that the vulcanizing agent is included in an amount of 3 to 7 parts by weight based on 100 parts by weight of the raw material rubber (natural rubber) from the viewpoint that the raw rubber is less sensitive to heat and chemically stable.

The vulcanization accelerator refers to an accelerator that promotes the vulcanization rate or accelerates the retardation in the initial vulcanization step.

Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamate, aldehyde-amine, aldehyde-ammonia, imidazoline, Or a combination thereof.

Examples of the thiol-based vulcanization accelerator include 2-mercaptobenzothiazole (MBT), dibenzothiazyl disulfide (MBTS), sodium salt of 2-mercaptobenzothiazole, zinc salt of 2-mercaptobenzothiazole , A copper salt of 2-mercaptobenzothiazole, a cyclohexylamine salt of 2-mercaptobenzothiazole, 2- (2,4-dinitrophenyl) mercaptobenzothiazole, 2- Ethyl 4-morpholinothio) benzothiazole, and combinations thereof. The thiazole-based compound may be used alone or in combination of two or more thereof.

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 rubber in order to maximize productivity improvement and rubber property enhancement through vulcanization speed promotion.

The vulcanization accelerating assistant may be any one selected from the group consisting of an inorganic vulcanization accelerator aid, an organic vulcanization accelerator aid, and a combination thereof, which is used in combination with the vulcanization accelerator to complete the promoting effect thereof .

As the inorganic vulcanization accelerating aid, any one selected from the group consisting of zinc oxide (ZnO), zinc carbonate, magnesium oxide (MgO), lead oxide, potassium hydroxide and combinations thereof may be used have. As the organic vulcanization accelerating auxiliary, there may be selected from the group consisting of stearic acid, zinc stearate, palmitic acid, linoleic acid, oleic acid, lauric acid, dibutyl ammonium oleate, derivatives thereof, Can be used.

In particular, the zinc oxide and the stearic acid may be used together as the vulcanization accelerating assistant. In this case, the zinc oxide is dissolved in the stearic acid to form an effective complex with the vulcanization accelerator, Thereby facilitating the crosslinking reaction of the rubber.

When the zinc oxide and the stearic acid are used together, they may be used in an amount of 5 to 10 parts by weight and 0.1 to 0.5 parts by weight, respectively, based on 100 parts by weight of the raw rubber to serve as an appropriate vulcanization accelerating auxiliary. If the content of the zinc oxide and the stearic acid is less than the above range, the vulcanization rate may be slow and the productivity may be deteriorated. If the content exceeds the above range, the scorch phenomenon may occur and the physical properties may be deteriorated.

The softening agent is added to the rubber composition in order to impart plasticity to the rubber to facilitate processing or to decrease the hardness of the vulcanized rubber, and means an oil or other material used in rubber compounding or rubber production. The softener may be selected from the group consisting of petroleum oils, vegetable oils, and combinations thereof, but the present invention is not limited thereto.

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

The softening agent is preferably included in an amount of 1 to 3 parts by weight based on 100 parts by weight of the raw rubber.

The rubber for topping 6b having the above configuration may be placed on the upper and lower sides of the steel cord 6a arranged in S1 and then rolled to manufacture the semi-finished product of the steel belt 6. [

S3. Cutting the rolled semi-finished product

The rolled tire steel belt semi-finished product can be cut to suit the application area. An unplated steel cord (6a) section is exposed during cutting. The exposed cross-section has no adhesive force and is easily separated from the rubber material, thereby deteriorating 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 starts at the interface of the steel belt layer 6. The first steel belt layer 6 and the second steel belt layer 6 have the same size and angle but are stacked in opposite directions when the steel belt layer 6 includes two layers. A relatively large amount of movement occurs at both ends of the layer and the second steel belt layer 6. This movement of the end of the steel belt layer 6 can cause the separation of the steel belt layer 6.

Therefore, in order to solve such a problem, it is necessary to increase the adhesive force of the exposed cross section. However, it is practically impossible to apply the plating bath and the electricity supplying equipment to all the cutting equipment in order to plate the cut surface of the steel cord (6a) semi-finished product which is rubberized in the tire cutting process. Also, it is not possible with the present technology to coat only the inner steel cord 6a section which is not plated in the rubber-finished semi-finished product.

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

S4. A step of applying a mixed oil to an end face of the exposed steel cord at the time of cutting to form a coating layer

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

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

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

Said Sorbitan Fatty Acid means a nonionic surfactant. 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 have a mixing weight ratio of naphthenic oil and sorbitan fatty acid of 90:10 to 70:30.

The mixed oil is effective in preventing corrosion and enhancing the bonding property. When the mixing amount exceeds the above range, the corrosion resistance and the bonding property may be lowered, and the mixing amount thereof may be less than the above range , The adhesive force of the finally obtained composition is decreased and it may be difficult to achieve the object to be obtained in the present invention.

Wherein the mixed oil has a specific gravity of 0.840 to 0.863 at 20 캜 and a kinematic viscosity of 30 to 45 cSt at 40 캜 and a kinematic viscosity of 3 to 7 cSt at 100 캜 and an ester index of 40 to 60 Lt; / RTI >

The mixed oil applied to the end face of the tire steel cord 6a exhibits good aging adhesion in a wide range so that the oil application amount 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 it. When the oil application amount is less than 1.0 g / cm 2, the oil application effect becomes insufficient. Conversely, when the application amount exceeds 7.5 g / cm 2, the oil application effect (adhesion effect) tends to be rather reduced. Which causes contamination of the conveyor belt of the cutting equipment and the bobbins wound around the cutting material, which is not desirable.

In addition, since the mixed oil according to the present invention does not need to be diluted to a separate concentration and does not have to be subjected to a drying process at a high temperature after application, the application operation can be easily performed.

The application of the mixed oil proceeds while the steel cord 6a is embedded in the rubber. A method of directly coating the cut surface of the steel cord 6a using a brush or a method of applying a certain amount of the cutting knife to the cut surface of the steel cord 6a during cutting.

A tire according to another embodiment of the present invention includes the tire steel belt (6).

The method for manufacturing the tire steel belt 6 can be applied to any method conventionally used for manufacturing tires, and a detailed description thereof will be omitted herein.

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

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[Preparation Example 1: Production of steel belt]

Naphthenic oil and sorbitan were mixed to prepare a mixed oil. Steel cord of 3 (0.20) +6 (0.35) structure which was not plated was prepared and the prepared mixed oil was applied to reproduce the cut surface of the steel cord. The coating amount is shown in Table 1 below.

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

A semi-finished steel belt was manufactured by rolling the rubber sheet having the composition shown in the following Table 2 on both sides of the steel cord coated with the mixed oil for 30 minutes at a temperature of 103 atm and at a temperature of 150 캜.

Item Weight portion caoutchouc 100 Carbon black 60 Zinc oxide 7 sulfur 5 Stearic acid 0.3 Benzothiazole 0.5  Aromatic oil 2.0 Resorcinol resin 1.5

[Experimental Example: Measurement of Physical Properties of the Rubber Composition]

The adhesion tests of the steel belts prepared in the above Examples and Comparative Examples were conducted according to ASTM D-2229, and the results are shown in Table 3 below.

division Mixed oil application amount (g / cm2) Initial adhesion force (kgf / in) Aging Adhesion (kgf / in) Thermal aging Moisture age Brine age   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

The initial adhesive strength was measured by measuring the adhesive strength between the rubber (topping rubber) and the steel cord of the steel belt while pulling the steel cord from the steel belt in the tensile tester of the steel belt specimen manufactured in Production Example 2 above.

The aging adhesion strength was measured by the same method as that of the initial adhesion strength test after the steel belt specimen was stored at 100 ° C for 3 weeks in order to examine the thermal aging adhesion strength in a high temperature atmosphere.

In order to evaluate the moisture aging adhesion under the moisture atmosphere, another specimen was stored for 3 weeks in a 96% relative humidity atmosphere at 70 ° C. After that, the adhesive strength was measured in the same manner as the initial adhesion strength measurement method. To evaluate the salt water aging adhesion, the adhesive strength was measured by the same method as that of the initial adhesive force after storage for 3 weeks in 20% NaCl aqueous solution.

As shown in Table 3, in the case of the test piece according to the present invention, the initial adhesive strength was similar to that of the conventional non-treated product (comparative example), but the aging adhesion in the extremely aging atmosphere Aging, water aging, salt water aging) were superior to those of conventional products.

As described above, the steel belt coated with the naphthenic oil and the mixed oil containing the sorbitan fatty acid according to the present invention has excellent properties in tearing property of the mixed oil when forming the composite with the tire rubber, An effect of maintaining the aging adhesion force in an extreme environment due to driving is expected. Therefore, the steel cord coated with the mixed oil on the cut surface has an advantage of exhibiting high aging adhesion to rubber of all compositions and can be utilized for reinforcing various rubber products including belts, straps and hoses in addition to tire reinforcing .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

1: Tread portion
2: side wall portion
3: bead portion
4: Carcass layer
5: Bead core
6: Steel belt layer
7: inner liner

Claims (11)

Steel cord,
Rubber for topping and
A coating layer to which a mixed oil is applied,
Wherein said mixed oil comprises naphthenic oil and sorbitan fatty acid
Tire steel belt. The method according to claim 1,
Wherein the mixed oil is a mixture of naphthenic oil and sorbitan fatty acid in a weight ratio of 90:10 to 70:30. The method according to claim 1,
Wherein the mixed oil has a specific gravity of 0.840 to 0.863 at 20 DEG C, a kinematic viscosity of 30 to 45 cSt at 40 DEG C or 3 to 7 cSt at 100 DEG C and an ester index of 40 to 60, belt. The method according to claim 1,
Wherein the sorbitan fatty acid is any one selected from the group consisting of sorbitan monooleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, and combinations thereof. The method according to claim 1,
Wherein the mixed oil application amount is 1.0 to 7.5 g / cm < 2 >. The method according to claim 1,
Wherein the topping rubber comprises 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, 0.1 to 0.5 parts by weight of stearic acid, and 1 to 3 parts by weight of a softener. The method according to claim 1,
Wherein the steel cord is brass plated. The method according to claim 1,
Wherein the coating layer is applied to a cross section of a steel cord exposed at the time of cutting a steel belt semi-finished product in which a rubber for topping is rolled on both sides of a steel cord. Steel cord arrangement step,
Placing the rubber for topping on both sides of the steel cord and rolling the same to manufacture a semi-finished steel belt product,
Cutting the rolled semi-finished product, and
Applying a mixed oil to an end face of the exposed steel cord at the time of cutting to form a coating layer,
Wherein said mixed oil comprises naphthenic oil and sorbitan fatty acid
Tire steel belt manufacturing method. 10. The method of claim 9,
Wherein the steel cord is arranged in a first steel cord layer arranged at 15 to 70 degrees with respect to the circumferential direction (0 DEG) and a second steel cord layer arranged in a direction symmetrical to the first steel cord layer Steel belt manufacturing method. A tire according to any one of claims 1 to 8 interposed between a carcass and a tread portion.

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