RUBBER REINFORCING MATERIAL WITH REDUCED WEIGHT, METHOD OF PREPARING THE SAME AND TIRE COMPRISING THE SAME

Abstract

This invention relates to rubber reinforcing material with reduced weight, a method for preparing the same, and a tire including the same. According to this invention, there is provided a rubber reinforcing material that has a thin thickness and a light weight, and yet has excellent durability. The reinforcing material not only reduces the weight of a tire, but also enables realization of improved rolling resistance.

Claims

1. A rubber reinforcing material comprising: a fiber base; an adhesive layer placed on the fiber base; and a rubber compound layer placed on the adhesive layer, wherein the rubber compound layer has a thickness of 2 to 200 , a t50 value of 150 to 220 seconds, and a t90 value of 300 to 350 seconds (wherein, the t50 value is a time (seconds) required to reach 50% of the maximum crosslinking density of the rubber compound layer, measured by a rheometer according to the ASTM D2084 standard test method, and the t90 value is a time (seconds) required to reach 90% of the maximum crosslinking density).

2. The rubber reinforcing material according to claim 1, wherein the rubber compound layer has a thickness of 20 to 40 .

3. The rubber reinforcing material according to claim 1, wherein the rubber compound layer has intrinsic surface resistance of 4.0×10.sup.8 ohm/sq to 8.0×10.sup.8 ohm/sq.

4. The rubber reinforcing material according to claim 1, wherein the rubber compound layer has adhesive strength of 17.0 N/inch or more according to the ASTM D4393 standard test method.

5. The rubber reinforcing material according to claim 1, wherein the fiber base comprises at least one of a fiber yarn and a textile base.

6. The rubber reinforcing material according to claim 1, wherein the adhesive layer comprises resorcinol-formaldehyde-latex (RFL).

7. A method for preparing the rubber reinforcing material according to claim 1, comprising steps of: preparing a fiber base; forming an adhesive layer on the fiber base; and coating a rubber compound solution on the adhesive layer and heat treating to form a rubber compound layer on the adhesive layer, wherein the rubber compound solution is prepared by adding one component included in the rubber compound solution under 50 to 110° C. and 30 to 50 rpm, and sequentially mixing the other components while stirring for 30 to 120 seconds.

8. The method according to claim 7, wherein the rubber compound solution comprises an elastic polymer, sulfur, a vulcanization accelerator, and a vulcanization retarder.

9. The method according to claim 7, wherein the rubber elastic polymer comprises one or more rubbers selected from the group consisting of natural rubber, styrene-butadiene rubber, butadiene rubber, chloroprene rubber, isobutylene rubber, isoprene rubber, nitrile rubber, butyl rubber, and neoprene rubber.

10. The method according to claim 8, wherein the rubber compound solution comprises 60 to 70 PHR (parts per hundred rubber) of natural rubber, 30 to 40 PHR of styrene-butadiene rubber, 1 to 5 PHR of the sulfur, 1 to 5 PHR of the vulcanization accelerator, and 0.1 to 0.5 PHR of the vulcanization retarder.

11. The method according to claim 8, wherein the rubber compound solution is prepared by mixing 60 to 70 PHR of natural rubber at a temperature of 60 to 70° C. under stirring at 30 to 40 rpm for 100 to 120 seconds (step (a)), adding 30 to 40 PHR of styrene-butadiene rubber to the composition comprising the mixture of step (a), and then mixing them at a temperature of 100 to 110° C. under stirring at 30 to 40 rpm for 30 to 60 seconds (step (b)), adding 1 to 5 PHR of the sulfur and 0.5 to 2.5 PHR of a first vulcanization accelerator to the composition comprising the mixture of step (b), and then mixing them at a temperature of 50 to 60° C. under stirring at 30 to 40 rpm for 30 to 60 seconds (step (c)), and adding 0.5 to 2.5 PHR of a second vulcanization accelerator and 0.1 to 0.5 PHR of the vulcanization retarder to the composition comprising the mixture of step (c), and then mixing them at a temperature of 70 to 80° C. under stirring at 40 to 45 rpm for 30 to 60 seconds (step (d)).

12. The method according to claim 8, wherein the rubber compound solution further comprises one or more additives selected from the group consisting of a peptizer, carbon black, a process oil, an activator, an antiaging agent, a petroleum resin, and an antioxidant.

13. The method according to claim 7, wherein the rubber compound layer is formed with a thickness of 2 to 200 .

14. A tire comprising the rubber reinforcing material according to claim 1.

15. The tire according to claim 14, wherein the rubber reinforcing material is applied to at least one of a cap ply, a belt, and a carcass.

Description

DESCRIPTION OF DRAWINGS

[0143] FIG. 1 is a partial cutting view of the tire according to one example of the invention.

[0144] FIG. 2 is a schematic cross-sectional view of the rubber reinforcing material according to one example of the invention.

[0145] FIG. 3 is a schematic diagram of the ply yarn.

[0146] FIG. 4 is a schematic cross-sectional view of the rubber reinforcing material according to another example of the invention.

[0147]

TABLE-US-00001 <Reference numerals> 10: tread 20: shoulder 30: side wall 40: bead 50: belt 60: inner liner 70: carcass 80: groove 90: cap ply 101: tire 110: ply yarn 111: primary twisted yarn 1 112: primary twisted yarn 2 201, 301: rubber reinforcing material 210: textile base 220: adhesive layer 230: rubber compound layer

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0148] Hereinafter, preferable examples are presented for better understanding of the invention. However, these examples are presented only as illustrations of the invention, and the invention is not limited thereby.

Preparation Example 1

[0149] According to step (1) to step (7) below, a rubber compound solution was prepared.

[0150] For the preparation of the rubber compound solution, a propeller type of agitator with a capacity of 10 L (container diameter 100 cm, propeller diameter 80 cm, propeller length 120 cm, model name SUPER-MIX MR203, manufactured by HADO Co., Ltd.) was used.

[0151] 60 PHR of natural rubber (20 Grade according to TSR classification standard, SIR20) and 0.1 PHR of a peptizer (Struktol A86) were mixed at a temperature of 70° C. under stirring at 40 rpm for 120 seconds [step (1)].

[0152] To the mixture obtained in step (1), 40 PHR of styrene-butadiene rubber (SBR-1502) was added, and then they were mixed at a temperature of 110° C. under stirring at 40 rpm for 60 seconds [step (2)].

[0153] To the mixture obtained in step (2), 50 PHR of carbon black (Corax® N330) and 6 PHR of a process oil (paraffin-based, P-2, MICHANG) were added, and then they were mixed at a temperature of 100° C. under stirring at 35 rpm for 60 seconds [step (3)].

[0154] To the mixture obtained in step (3), 5 PHR of a first activator (ZnO), 2 PHR of a second activator (stearic acid), and 1.5 PHR of first antiaging agent (TMDQ) were added, and then, they were mixed at a temperature of 110° C. under stirring at 45 rpm for 60 seconds [step (4)].

[0155] To the mixture obtained in step (4), 7 PHR of a petroleum resin (HIKOTACK® P-90), 1 PHR of a second antiaging agent (6PPD), and 2.5 PHR of an antioxidant (wax) were added, and then they were mixed at a temperature of 100° C. under stirring at 40 rpm for 60 seconds [step (5)].

[0156] The mixture obtained in step (5) was left at room temperature (25° C.) for 2 hours, and then mixed. Subsequently, it was mixed at a temperature of 70° C. under stirring at 40 rpm for 120 seconds [step (5.5)].

[0157] To the mixture obtained in step (5.5), 3.4 PHR of sulfur and 0.85 PHR of a first 1 vulcanization accelerator (TBBS) were added, and then they were mixed at a temperature of 60° C. under stirring at 40 rpm for 30 seconds [step (6)].

[0158] To the mixture obtained in step (6), 0.6 PHR of a second vulcanization accelerator (DPG) and 0.2 PHR of a vulcanization retarder (N-(cyclohexylthio)phthalimide) were added, and then they were mixed at a temperature of 80° C. under stirring at 45 rpm for 30 seconds [step (7)].

Preparation Example 2

[0159] A rubber compound solution was prepared by the same method as Preparation Example 1, except that the temperatures in step (1), step (2), step (6), and step (7) were changed as follows. [0160] step (1): 60° C. [0161] step (2): 110° C. [0162] step (6): 50° C. [0163] step (7): 70° C.

Preparation Example 3

[0164] A rubber compound solution was prepared by the same method as Preparation Example 1, except that the stirring speeds in step (1), step (2), step (6), and step (7) were changed as follows. [0165] step (1): 35 rpm [0166] step (2): 35 rpm [0167] step (6): 30 rpm [0168] step (7): 40 rpm

Preparation Example 4

[0169] A rubber compound solution was prepared by the same method as Preparation Example 1, except that the mixing times of the mixture in step (1), step (2), step (6), and step (7) were changed as follows. [0170] step (1): 100 seconds [0171] step (2): 45 seconds [0172] step (6): 60 seconds [0173] step (7): 60 seconds

Preparation Example 5

[0174] A rubber compound solution was prepared by the same method as Preparation Example 1, except that the contents of natural rubber, styrene-butadiene rubber, and carbon black in step (1), step (2), and step (3) were changed as follows. [0175] step (1): natural rubber 70 PHR [0176] step (2): styrene-butadiene rubber 30 PHR [0177] step (3): carbon black 55 PHR

Comparative Preparation Example 1

[0178] A rubber compound solution was prepared by the same method as Preparation Example 1, except that the temperatures in step (6) and step (7) were changed as follows. [0179] step (6): 45° C. [0180] step (7): 70° C.

Comparative Preparation Example 2

[0181] A rubber compound solution was prepared by the same method as Preparation Example 1, except that the temperatures in step (1), step (2), step (6), and step (7) were changed as follows. [0182] step (1): 75° C. [0183] step (2): 120° C. [0184] step (6): 70° C. [0185] step (7): 90° C.

Comparative Preparation Example 3

[0186] A rubber compound solution was prepared by the same method as Preparation Example 1, except that the stirring speeds (rpm) in step (1), step (2), step (6), and step (7) were changed as follows. [0187] step (1): 25 rpm [0188] step (2): 35 rpm [0189] step (6): 35 rpm [0190] step (7): 40 rpm

Comparative Preparation Example 4

[0191] A rubber compound solution was prepared by the same method as Preparation Example 1, except that the stirring speeds (rpm) in step (1), step (2), step (6), and step (7) were changed as follows. [0192] step (1): 45 rpm [0193] step (2): 40 rpm [0194] step (6): 45 rpm [0195] step (7): 55 rpm

Comparative Preparation Example 5

[0196] A rubber compound solution was prepared by the same method as Preparation Example 1, except that the mixing times in step (1), step (2), step (6), and step (7) were changed as follows. [0197] step (1): 100 seconds [0198] step (2): 120 seconds [0199] step (6): 150 seconds [0200] step (7): 60 seconds

Examples 1 to 5

[0201] (1) Preparation of Textile Base

[0202] Nylon filaments (primary twisted yarn 1) of 1260 de and aramid filaments (primary twisted yarn 2) of 1500 de were prepared. Using a cable corder, primary twisting (counterclockwise direction) and secondary twisting (clockwise direction) of the filaments 1 and 2 were simultaneously conducted to prepare a ply yarn (110) having a twist number of 300 TPM.

[0203] Using the ply yarn (110) as a warp yarn and cotton yarn as a weft yarn, fabric was woven to prepare a textile base (210) with a thickness of 0.04 mm.

[0204] (2) Formation of Adhesive Layer

[0205] The textile base (210) was dipped in an adhesive coating solution including 15 wt % of resorcinol-formaldehyde-latex (RFL) and 85 wt % of solvent (water, H.sub.2O), and then heat treated at 150° C. for 100 seconds to form an adhesive layer (220).

[0206] (3) Formation of Rubber Compound Layer

[0207] Subsequently, using a comma coater, each rubber compound solution of the preparation examples was coated on the adhesive layer (220) in the coating amount per unit area of 120˜130 g/m.sup.2, and then the solvent was evaporated at a temperature of 70° C. to prepare a rubber reinforcing material (201) in which a rubber compound layer (230) is formed.

[0208] (4) Cutting

[0209] The rubber reinforcing material (201) was cut to a width of 10 mm, thus preparing a rubber reinforcing material for a cap ply (90). For the cutting, a cutter knife was used.

[0210] (5) Manufacture of Tire

[0211] The cut rubber reinforcing material was applied for the manufacture of a 205/55R16 standard tire. For the manufacture of a tire, a body ply including a 1300De/2ply HMLS tire cord and a steel cord belt were used.

[0212] Specifically, rubber for the body ply was laminated on an inner liner rubber, a bead wire, and a belt part were laminated, and then the above-prepared rubber reinforcing material was applied, and rubber layers for the formation of tread part, shoulder part, and side wall part were sequentially formed to manufacture a green tire. The green tire was put in a vulcanization mold, and vulcanized at 170° C. for 15 minutes to manufacture a tire.

Comparative Examples 1 to 5

[0213] Rubber reinforcing materials and tires including the same were prepared by the same method as Examples 1 to 5, except that, when forming the rubber compound layer, each rubber compound solution obtained in comparative preparation examples was used as a rubber compound solution.

Experimental Example

[0214] (1) Thickness

[0215] In each rubber reinforcing material according to examples and comparative examples, the thickness (t1) of the fiber base and the rubber compound layer were measured using a vernier caliper of Mitutoyo Corporation.

[0216] (2) Vulcanization Characteristics of Rubber Compound Layer (t50, t90)

[0217] From each rubber reinforcing material according to the examples and comparative examples, a specimen of the rubber compound layer was collected. According to the ASTM D2084 standard test method, t50 and t90 values of the specimen were measured using a rheometer (MDR 2000, Alpha Technologies).

[0218] (3) Pressure-Sensitive Tack of Adhesives

[0219] According to the ASTM D2979 standard test method, pressure-sensitive tack of adhesives of the rubber compound layer were measured under the following conditions. [0220] cylinder diameter: 10 mm [0221] load: 300 gf [0222] detachment speed: 5 mm/min [0223] start load: 10 gf [0224] loading speed at the beginning of test: 10 mm/min [0225] target load-reaching speed: 0.2 mm/min [0226] maintenance time: 20 s

[0227] (4) Adhesive Strength

[0228] According to the ASTM D4393 standard test method, strap peel adhesion of the rubber compound layer was tested. The test was conducted at a cross head speed of 125 mm/min using an Instron clamp (Grip, CAT. No. 2712-041).

[0229] (5) Fatigue Strength Maintenance Rate

[0230] Fatigue strength maintenance rate was measured through a bending fatigue test. A specimen was prepared with a length of 30 cm and a width of 1 inch. Vulcanization was conducted at 170° C. for 15 minutes. Before the test, the specimen was installed in a pulley of a bending fatigue tester, and then left at 100° C. for 30 minutes. Further, the specimen was bent for 25,000 cycles under conditions of 150 RPM, 100° C., and a pulley size 1 inch. Herein, the pulley size means the diameter of pulley on which the specimen is hung. Adhesive strength of the specimen after running, compared to the adhesive strength before running, is defined as fatigue strength maintenance rate.

[0231] (6) Intrinsic Surface Resistance

[0232] For the specimen prepared with a length of 30 cm and a width of 1 inch, intrinsic surface resistance was measured using an electric resistance measuring device (model name: Insulation Tester 1550C, manufactured by FLUKE).

TABLE-US-00002 TABLE 1 Rubber reinforcing material Example 1 Example 2 Example 3 Example 4 Example 5 Rubber compound solution Preparation Preparation Preparation Preparation Preparation Example 1 Example 2 Example 3 Example 4 Example 5 Rubber Thickness (   ) 40 40 40 40 40 compound t50 (s) 208 209 205 206 181 layer t90 (s) 335 336 333 334 311 Pressure-sensitive 209.8 210.8 208.1 212.2 209.6 adhesion (N/inch) Adhesive strength 17.2 17.0 17.2 17.5 17.2 (N/inch) Fatigue strength 100 100 101 100 101 maintenance rate (%) Intrinsic surface 7.3 × 10.sup.8 7.0 × 10.sup.8 6.9 × 10.sup.8 6.8 × 10.sup.8 4.3 × 10.sup.8 resistance (ohm/sq)

TABLE-US-00003 TABLE 2 Rubber reinforcing material Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Rubber compound solution Comparative Comparative Comparative Comparative Comparative Preparation Preparation Preparation Preparation Preparation Example 1 Example 2 Example 3 Example 4 Example 5 Rubber Thickness (   ) 42 43 43 44 46 compound t50 (s) 222 140 233 145 135 layer t90 (s) 370 298 375 289 280 Pressure sensitive 191.4 185.5 184.3 177.5 164 adhesion (N/inch) Adhesive property 16.3 16.0 16.1 16.0 15.9 (N/inch) Fatigue strength 96 95 93 92 95 maintenance rate (%) Intrinsic surface 6.2 × 10.sup.8 6.0 × 10.sup.8 5.1 × 10.sup.8 8.1 × 10.sup.8 7.0 × 10.sup.8 resistance (ohm/sq)

[0233] Referring to Tables 1 and 2, it was confirmed that the rubber compound layer formed using each rubber compound solution of Preparation Examples 1 to 5 has excellent vulcanization characteristics (t50, t90), pressure-sensitive adhesion, and adhesive strength, and yet has a high fatigue strength maintenance rate and low intrinsic surface resistance, compared to those formed using the rubber compound solution of Comparative Preparation Example 1 to 5.

[0234] (7) Property Evaluation of Tire

[0235] Using a tire cord prepared by a rolling process (using two-ply yarn made of nylon with fineness of 840 denier as a warp yarn, warp yarn density of 25/inch), a 205/60 R16 standard tire was manufactured as a reference example.

[0236] For the tires of the reference example and Example 1, the following properties were measured. The property values of the tire of Example 1 is a value converted based on the property value (100%) of the reference example. [0237] material weight: the weights of rubber reinforcing material of Example 1 and the tire cord of the reference example [0238] tire weight: weights of the tires of Example 1 and the reference example [0239] high speed running performance: measured according to the US FMVSS 139H standard test method [0240] Durability I: measured according to the US FMVSS 139E standard test method [0241] Durability II: measured according to the Europe ECE-R119 standard test method [0242] Rolling resistance (RRC): measured according to the ISO 28580 standard test method

TABLE-US-00004 TABLE 3 Reference Tire Example 1 (index) Example (index) Material weight 30 100 Tire weight 98 100 High speed running performance 102 100 Durability I 102 100 Durability II 102 100 Rolling resistance (RRC) 102 100

[0243] Referring to Table 3, it was confirmed that the tire of Example 1 including the rubber reinforcing material according to the embodiment of the invention has a light weight, and yet has excellent high speed running performance, durability, and rolling resistance, compared to the tire of the reference Example.