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 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 fiber base is a fabric woven with warp yarns and weft yarns, the warp yarn is a single-ply yarn with fineness of 420 denier to 800 denier, and is included in the fabric at a warp yarn density of 55/inch to 65/inch, and the weft yarn has dry heat shrinkage of -1.0 % to +3.0 % according to the standard test method of ASTM D 885 (177° C., 2 minutes, load of 0.05 g/de).

2. The rubber reinforcing material according to claim 1, wherein the warp yarn and the weft yarn respectively comprise one or more materials selected from the group consisting of nylon, rayon, aramid, polyester, and cotton.

3. The rubber reinforcing material according to claim 1, wherein the weft yarn is a single-ply yarn with fineness of 420 denier to 800 denier, and is included in the fabric at the weft yarn density of 0.05/mm to 5/mm.

4. The rubber reinforcing material according to claim 1, wherein the fiber base has a thickness of 100 .Math.m to 600 .Math.m.

5. The rubber reinforcing material according to claim 1, wherein the fiber base has dry heat shrinkage of -1.0 % to +3.0 % according to the standard test method of ASTM D 885 (specimen size: weft yarn direction length 60 cm x width 1 cm, 177° C., 2 minutes, load of 0.05 g/de based on weft yarn).

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

7. The rubber reinforcing material according to claim 1, wherein the rubber compound layer comprises one or more elastic polymers selected from the group consisting of natural rubber and synthetic rubber.

8. The rubber reinforcing material according to claim 1, wherein the rubber compound layer has a thickness of 5 .Math.m to 200 .Math.m.

9. The rubber reinforcing material according to claim 1, wherein the rubber reinforcing material has a maximum load of 1.0 kgf to 1.2 kgf and tensile strain of 11 % to 13 % in the tensile test for a specimen (size weft yarn direction length 25 cm x width 1 cm) under 150° C.

10. A method for preparing the rubber reinforcing material according to claim 1, comprising steps of: preparing a fiber base woven at the warp yarn density of 55/inch to 65/inch, using warp yarn, which is a single-ply yarn having fineness of 420 denier to 800 denier, and weft yarn having dry heat shrinkage of -1.0 % to +3.0 % according to the standard test method of ASTM D 885(177° C., 2 minutes, load of 0.05 g/de); forming an adhesive layer on the fiber base; and applying a rubber coating solution on the adhesive layer and heat treating to form a rubber compound layer on the adhesive layer.

11. The method according to claim 10, wherein the adhesive layer comprises resorcinol-formaldehyde-latex (RFL).

12. The method according to claim 10, wherein the rubber coating solution comprises 10 wt% to 40 wt% of one or more elastic polymer compositions selected from the group consisting of natural rubber and synthetic rubber, and 60 wt% to 90 wt% of a solvent.

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

14. The tire according to claim 13, wherein the rubber reinforcing material is applied in 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 shows the images of the exterior of the fiber bases according to (a) Example 1 and (b) Comparative Example 1, taken by a camera, after measuring dry heat shrinkage.

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 201: rubber reinforcing material 210: fiber base 220: adhesive layer 230: rubber compound layer

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0146] 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.

Example 1

[0147] As warp yarn, single-ply yarn (twist of 200 TPM) with fineness of 630 denier, made of nylon, was prepared. As weft yarn, single-ply yarn (twist of 200 TPM) with fineness of 260 denier, made of cotton, was prepared. The weft yarn had dry heat shrinkage of -0.16 % according to the standard test method (177° C., 2 minutes, 0.05 g/de load) of ASTM D 885 (see experimental examples below).

[0148] Using the warp yarn and weft yarn, a fiber base (210) with a thickness of 45 .Math.m having warp yarn density of 55/inch (density between warp yarns of 90%) and weft yarn density of 2.5/mm was woven.

[0149] The fiber base (210) was immersed in an adhesive coating solution including 15 wt% of resorcinol-formaldehyde-latex (RFL) and 85 wt% of a solvent (water, H.sub.2O), and then heat treated at 150° C. for 100 seconds to form an adhesive layer (220).

[0150] Subsequently, using a comma coater, a rubber coating layer was applied on the adhesive layer (220) in the amount per unit area of 120 ~ 130 g/m.sup.2, and then solvents were evaporated at 70° C. to prepare a rubber reinforcing material (201) including a rubber compound layer (230) with a thickness (t1) of 10 .Math.m.

[0151] Herein, as the rubber coating solution for the formation of the rubber compound layer (230), a solution in which an elastic polymer composition was dispersed in a mixed solvent of toluene and tetrahydrofuran mixed at the weight ratio of 20:80, at a concentration of 12 wt%, was used.

[0152] As the elastic polymer composition, a mixture of 100 parts by weight of styrene butadiene rubber (SBR), 60 parts by weight of carbon black, 20 parts by weight of para oil, 3 parts by weight of zinc oxide, 2 parts by weight of stearic acid, 2 parts by weight of an anti-aging agent (RUBBER ANTIOXIDANTS, BHT), 2 parts by weight of sulfur, and 1 part by weight of vulcanization accelerators (ZnBX) was used.

[0153] 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 cutting, a cutter knife was used.

[0154] The cut rubber reinforcing material was applied for the manufacture of a tire of a 205/55R16 standard. For the manufacture of the tire, a body ply including 1300De/2ply HMLS tire cord and steel cord belt were used.

[0155] Specifically, rubber for the body ply was laminated on inner liner rubber, bead wire and a belt part were laminated, and then the above-prepared rubber reinforcing material was introduced, and rubber layers for the formation of a tread part, a shoulder part, and a side wall part were sequentially formed, thus manufacturing a green tire. The green tire was put in a vulcanization mold and vulcanized at 170° C. for 15 minutes, thus manufacturing a tire.

Example 2

[0156] A rubber reinforcing material and a tire including the same were prepared by the same method as Example 1, except that single-ply yarn (twist of 200 TPM) with fineness of 260 denier, made of rayon, was used as weft yarn. The weft yarn had dry heat shrinkage of +0.27 % according to the standard test method (177° C., 2 minutes, 0.05 g/de load) of ASTM D 885 (see experimental examples below).

Comparative Example 1

[0157] A rubber reinforcing material and a tire including the same were prepared by the same method as Example 1, except that a single-ply yarn (twist of 200 TPM) with fineness of 630 denier, made of nylon, was used as weft yarn. The weft yarn had dry heat shrinkage of +5.06 % according to the standard test method (177° C., 2 minutes, 0.05 g/de load) of ASTM D 885 (see experimental examples below).

Comparative Example 2

[0158] A rubber reinforcing material and a tire including the same were prepared by the same method as Example 1, except that cotton covered nylon yarn (twist of 200 TPM) with fineness of 160 denier was used as weft yarn. The weft yarn had dry heat shrinkage of +1.04% according to the standard test method (177° C., 2 minutes, 0.05 g/de load) of ASTM D 885 (see experimental examples below).

Experimental Example

Measurement of Thickness

[0159] The thicknesses of the fiber base and the rubber compound layer in each rubber reinforcing material according to the examples and comparative examples were measured using vernier calipers of Mitutoyo Corporation.

Measurement of Dry Heat Shrinkage of Weft Yarn

[0160] According to the standard test method of ASTM D 885, a load of 0.05 g/de was applied to each weft yarn specimen (length 60 cm) used in the examples and comparative examples, heat of 177° C. was applied for 2 minutes, and then a change in the length of the weft yarn specimen was measured. It was measured a total of 5 times, and the average rate of change (%) in the length of the weft yarn specimen is shown in the following Table 1. In case the dry heat shrinkage value is (+), it means shrinkage behavior, and in case the value is (-), it means relaxation behavior.

Measurement of Dry Heat Shrinkage of Fiber Base

[0161] According to the standard test method of ASTM D 885, a load of 0.05 g/de, on the basis of fineness of weft yarn, was applied to each fiber base specimen according to the examples and comparative examples (weft yarn direction length 60 cm x width 1 cm) in the weft yarn direction, heat of 177° C. was applied for 2 minutes, and then changes in the length and width of the fiber base specimen were measured. It was measured a total of 5 times, and the average rate of change (%) in the area of the fiber base specimen is shown in the following Table 1. In case the dry heat shrinkage value is (+), it means shrinkage behavior, and in case the value is (-), it means relaxation behavior.

TABLE-US-00002 Dry heat shrinkage (%) Example 1 Example 2 Comparative Example 1 Comparative Example 2 Weft yarn -0.16 + 0.27 + 5.06 -1.04 Fiber base -0.25 + 0.21 + 5.02 -1.08

Measurement of Dry Heat Shrinkage of Rubber Reinforcing Material

[0162] According to the standard test method of ASTM D 885, a load (5 g or 10 g) was applied to each rubber reinforcing material specimen according to the examples and comparative examples (weft yarn direction length 60 cm x width 1 cm) in the weft yarn direction, heat (25° C., 150° C., 160° C., or 177° C.) was applied for 2 minutes, and then changes in the length and width of the rubber reinforcing material specimen were measured. It was measured a total of 5 times, and the average rate of change (%) in the area of the rubber reinforcing material specimen is shown in the following Table 2. In case the dry heat shrinkage value is (+), it means shrinkage behavior, and in case the value is (-), it means relaxation behavior.

TABLE-US-00003 Dry heat shrinkage (%) Example 1 Comparative Example 1 load 5 g load 10 g load 5 g load 10 g @ 25° C. - 0.21 - 0.35 - 0.01 - 0.18 @ 150° C. - 1.03 - 2.94 - 0.08 - 0.19 @ 160° C. - 1.05 - 2.37 - 0.07 - 0.30 @ 177° C. - 2.32 - 1.69 - 0.02 + 0.03

Exterior of Fiber Base

[0163] After measuring dry heat shrinkage of the fiber base according to Experimental Example 3, the exterior of each fiber base according to Example 1 and Comparative Example 1 was photographed by a camera. The photographed image is shown in FIG. 3 ((a): Example 1, (b) Comparative Example 1).

[0164] Referring to FIG. 3, it is confirmed that in the fiber base of Comparative Example 1, wrinkles were generated due to the overlap of dislocated warp yarns. To the contrary, it is confirmed that in the fiber base of Example 1, the arrangement of warp yarns was uniform and wrinkles were not generated.

Measurement of Tensile Properties of Rubber Reinforcing Material

[0165] Each rubber reinforcing material specimen according to Example 1 and Comparative Example 1(size: weft yarn direction length 25 cm x width 1 cm) was mounted in a half chamber to measure tensile properties.

[0166] The specimen was fitted in an upper grip and a lower grip of the half chamber (distance between grips: 20 cm) in the direction perpendicular to the horizontal plane. To the specimen part (heated length 12 cm) positioned between the grips, heat (25° C., 150° C., 160° C., or 177° C.) was applied for 2 minutes, and then the specimen was pulled at a speed of 300 mm/min. Maximum load (kgf) and tensile strain when the specimen was broken were measured. They were measured a total of 5 times, and the average values are shown in the following Table 3.

TABLE-US-00004 Tensile properties Example 1 Comparative Example 1 Maximum load (kgf) Tensile strain (%) Maximum load (kgf) Tensile strain (%) @ 25° C. 1.96 19.12 17.33 34.72 @ 150° C. 1.13 11.60 11.90 32.08 @ 160° C. 1.06 14.80 11.40 33.50 @ 177° C. 0.99 14.80 11.07 33.95

[0167] Referring to Table 3, the rubber reinforcing material of Comparative Example 1 exhibited high tensile strain compared to the rubber reinforcing material of Example 1. This means that it is difficult to prepare a uniform product with the rubber reinforcing material of Comparative Example 1, due to overlap of fabrics in the preparation process. Thus, it can be expected that the rubber reinforcing material of Comparative Example 1 has relatively poor preparation uniformity.

Evaluation of Tire Properties

[0168] A 205/60 R16 standard tire applying a tire cord prepared by a rolling process (using two-ply yarn made of nylon with fineness of 840 denier as warp yarn, warp yarn density of 25/inch) was prepared as a reference example.

[0169] For each tire of the reference example and Example 1, the following properties were measured. The property values of the tire of Example 1 are values converted based on the property values (100%) of the tire of the reference example.

[0170] material weight: weights of the rubber reinforcing material of Example 1 and the tire cord of the reference example [0171] tire weight: weights of tires of Example 1 and the reference example [0172] high speed running performance: measured according to the standard test method of US FMVSS 139H [0173] durability I: measured according to the standard test method of US FMVSS 139E [0174] durability II: measured according to the standard test method of Europe ECE-R119 [0175] rolling resistance (RRc): measured according to the standard test method of ISO 28580

TABLE-US-00005 Tire Example 1 (index) Reference example (index) Material weight 30 100 Tire weight 98 100 High speed running performance 104 100 Durability I 106 100 Durability II 105 100 Rolling resistance (RRc) 102 100

[0176] Referring to Table 4, it was confirmed that since the tire of Example 1 includes the rubber reinforcing material according to the embodiment of the invention, it has reduced weighted, and yet exhibits excellent high speed running performance, durability, and rolling resistance.