Tire cord fabric and pneumatic tire

Abstract

The invention provides a tire cord fabric and a pneumatic tire, which can improve the tire uniformity by improving the processability of the cord fabric during rolling and slitting. In the tire cord fabric (1) provided with a plurality of warp yarns (2) arranged in parallel and weft yarns (3) crossed with respect to the warp yarns (2) at a low density, the warp yarns (2) are organic fiber cords containing polyethylene terephthalate fibers or aramid fibers, the weft yarns (3) are cotton spun yarns, the fineness of the weft yarns (3) is in the range of 150 dtex to 350 dtex, and the density of the weft yarns (3) is in the range of 2.0 pieces / 50 mm to 4.0 pieces / 50 mm. The pneumatic tire is provided with a belt cover layer (18) formed by spirally winding a strip (10) of a rubber-coated cord fabric (1) in the circumferential direction of the tire.

Description

Technical Field

[0001] The present invention relates to a tire cord fabric and a pneumatic tire using a belt material of the cord fabric as a belt covering layer, and more specifically, to a tire cord fabric capable of improving the processability of the cord fabric during calendering and slitting, and a pneumatic tire capable of improving tire uniformity by using the tire cord fabric. Background Art

[0002] In a pneumatic tire, there is a pneumatic tire having a carcass layer spanned between a pair of bead portions, a belt layer arranged on the outer circumference of the carcass layer, and a belt covering layer arranged on the outer circumference of the belt layer. The belt covering layer is formed by spirally winding a belt of a cord fabric covered with rubber along the circumference of the tire. By providing such a belt covering layer, it is possible to prevent the belt layer from bulging when the tire rolls, and as a result, it is possible to improve the high-speed durability of the pneumatic tire and suppress road noise.

[0003] Conventionally, in tire cord fabrics that are the starting materials of the band material of the belt covering layer, highly rigid organic fiber cords are used in the warp yarns (for example, see Patent Document 1). Such tire cord fabrics are processed into the band material of the belt covering layer by a calendering process of the cord fabric coating rubber and a slitting process of cutting the cord fabric along the warp yarns.

[0004] However, if a high elongation yarn (e.g., undrawn yarn of polyethylene terephthalate fiber, yarn of a core-sheath structure with polyethylene terephthalate fiber as a core and cotton as a sheath) is used as the weft yarn of the tire cord fabric, the processability of the cord fabric during calendering and slitting is poor, so that the width of the cord fabric and the belt material becomes unstable, and there is a problem that the number of warp yarns included in the belt material becomes uneven. As a result, there is a problem that the uniformity of the pneumatic tire having the belt cover layer formed using such a slit material is deteriorated.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 5029795 Summary of the invention

[0008] Problems to be solved by the invention

[0009] An object of the present invention is to provide a tire cord fabric capable of improving the processability of the cord fabric during calendering and slitting, and a pneumatic tire capable of improving tire uniformity by using the tire cord fabric.

[0010] Means for solving problems

[0011] The tire cord fabric of the present invention for achieving the above-mentioned object comprises a plurality of warp yarns arranged in parallel and weft yarns inserted crosswise with respect to the warp yarns at a low density, and the tire cord fabric is characterized in that:

[0012] The warp yarn is an organic fiber cord including polyethylene terephthalate fiber or aramid fiber, and the weft yarn is a cotton spun yarn. The fineness of the weft yarn is in the range of 150 dtex to 350 dtex, and the density of the weft yarn is in the range of 2.0 yarns / 50 mm to 4.0 yarns / 50 mm.

[0013] In addition, the pneumatic tire of the present invention for achieving the above-mentioned purpose comprises: a carcass layer, which is spanned between a pair of bead portions; a belt layer, which is arranged on the outer peripheral side of the carcass layer; and a belt covering layer, which is arranged on the outer peripheral side of the belt layer and is formed by spirally winding a belt material of a cord fabric covered with rubber along the tire circumferential direction, wherein the pneumatic tire is characterized in that:

[0014] The cord fabric includes a plurality of warp yarns arranged in parallel, and weft yarns cross-inserted at a low density relative to the warp yarns, the warp yarns are organic fiber cords containing polyethylene terephthalate fibers or aromatic polyamide fibers, the weft yarns are cotton spun yarns, the fineness of the weft yarns is in the range of 150 dtex to 350 dtex, and the density of the weft yarns is in the range of 2.0 yarns / 50 mm to 4.0 yarns / 50 mm.

[0015] Effects of the Invention

[0016] In the present invention, the tire cord includes a plurality of warp yarns arranged in parallel and weft yarns inserted crosswise with respect to the warp yarns at a low density, the warp yarns are organic fiber cords containing polyethylene terephthalate fibers or aramid fibers, the weft yarns are cotton spun yarns, the fineness of the weft yarns is in the range of 150 dtex to 350 dtex, and the density of the weft yarns is in the range of 2.0 yarns / 50 mm to 4.0 yarns / 50 mm, so that the processability of the tire cord during calendering and slitting can be improved. As a result, the width of the tire cord and the belt material can be stabilized, and the number of warp yarns contained in the belt material can be suppressed from being uneven. As a result, the uniformity of the pneumatic tire having a belt cover layer formed using the belt material can be improved.

[0017] In the present invention, it is preferred that the warp and weft yarns are impregnated with an adhesive composition containing an epoxy compound. The adhesive composition containing an epoxy compound is effective as an adhesive treatment agent for the warp yarn as described above, but the temperature becomes high when the adhesive composition containing an epoxy compound is impregnated. Therefore, if the weft yarn is an undrawn yarn of polyethylene terephthalate fiber or a yarn of a core-sheath structure with polyethylene terephthalate fiber as a core and cotton as a sheath, it is easily affected by heat. In contrast, when cotton spun yarn is used as the weft yarn, it is not easily affected by heat even if the adhesive composition containing an epoxy compound is impregnated.

[0018] In the present invention, it is preferred that the breaking elongation of the weft yarn is 10% or less. This can improve the processability of the cord fabric during calendering and slitting.

[0019] In the present invention, it is preferred that the warp yarn has a two-twisted structure or a three-twisted structure. When the warp yarn has a two-twisted structure or a three-twisted structure, a good effect is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a plan view schematically showing a tire cord fabric constituted by an embodiment of the present invention.

[0021] Figure 2 (a) and (b) are cross-sectional views respectively showing warp yarns constituting a tire cord fabric.

[0022] Figure 3 It is a plan view showing a strip cut from a rubber-covered tire cord fabric.

[0023] Figure 4 This is a meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention.

[0024] Figure 5 Yes Figure 4 A developed view of the belt layer and belt cover layer extraction of a pneumatic tire is shown. DETAILED DESCRIPTION

[0025] Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 This is a diagram schematically showing a tire cord fabric configured according to an embodiment of the present invention.

[0026] like Figure 1 As shown, the cord fabric 1 of this embodiment is composed of a plurality of warp yarns 2 arranged in parallel and weft yarns 3 inserted at a low density to cross the warp yarns 2. The weft yarns 3 are folded back at both ends of the cord fabric 1 in the width direction.

[0027] In the tire cord 1, the warp yarn 2 is an organic fiber cord comprising polyethylene terephthalate fiber or aramid fiber. More specifically, as the organic fiber cord, for example, a cord formed by twisting together a plurality of primary twisted yarns consisting of polyethylene terephthalate fiber, a mixed cord formed by twisting together at least one primary twisted yarn consisting of aramid fiber and at least one primary twisted yarn consisting of nylon fiber, a mixed cord formed by twisting together at least one primary twisted yarn consisting of aramid fiber and at least one primary twisted yarn consisting of polyethylene terephthalate fiber, etc. can be used. Since such an organic fiber cord has high rigidity, it is effective in improving the high-speed durability of a pneumatic tire and suppressing road noise. In particular, the warp yarn 2 preferably has the following Figure 2 (a) shows a two-twisted structure in which two primary twisted yarns 2A and 2B are twisted together, or a structure having a twisted structure as shown in FIG. Figure 2 As shown in (b), the three-twisted structure is formed by twisting three primary twisted yarns 2A, 2B, and 2C together.

[0028] In addition, the intermediate elongation of the organic fiber cord constituting the warp yarn 2 at a load of 2.0 cN / dtex is preferably 5.0% or less. If the intermediate elongation is greater than 5.0%, the improvement effect of road noise is reduced. In addition, the intermediate elongation at a load of 2.0 cN / dtex is the elongation (%) of the sample cord measured by a tensile test under the conditions of a clamping interval of 250 mm and a tensile speed of 300±20 mm / min in accordance with the "Test Method for Chemical Fiber Tire Cord" of JIS-L1017.

[0029] In addition, the total fineness of the organic fiber cords constituting the warp yarn 2 is preferably in the range of 1800 dtex to 5000 dtex. If the total fineness is less than 1800 dtex, the strength is low, so the durability is reduced. On the other hand, if the total fineness exceeds 5000 dtex, the reinforcing layer in the pneumatic tire will become thicker than required, so it is not preferred.

[0030] In the cord fabric 1, the weft yarn 3 is a cotton yarn. The fineness of the weft yarn 3 is in the range of 150 dtex to 350 dtex, and the density of the weft yarn 3 is in the range of 2.0 yarns / 50 mm to 4.0 yarns / 50 mm. Such weft yarns 3 play a moderate breaking strength and a moderate restraining force. In addition, the density of the weft yarn 3 is the insertion density of the weft yarn 3 arranged along the length direction of the warp yarn 2, which is the insertion density per 50 mm length of the warp yarn 2.

[0031] The cord fabric 1 is processed into a rubber cord by a calendering process in which the cord fabric 1 is coated with rubber from both sides when passing between a pair of rollers and a slitting process in which the cord fabric 1 is cut along the warp yarn 2. Figure 3 The strip 10 shown in FIG. Figure 3In the embodiment, the tape 10 is composed of a plurality of warp yarns 2 arranged in parallel along the longitudinal direction thereof, weft yarns 3 crossing the warp yarns 2 , and a covering rubber 4 covering the warp yarns 2 and the weft yarns 3 .

[0032] The above-mentioned cord fabric 1 includes a plurality of warp yarns 2 arranged in parallel, and weft yarns 3 inserted crosswise with respect to the warp yarns 2 at a low density, the warp yarns 2 are organic fiber cords containing polyethylene terephthalate fibers or aramid fibers, the weft yarns 3 are cotton spun yarns, the fineness of the weft yarns 3 is in the range of 150 dtex to 350 dtex, and the density of the weft yarns 3 is in the range of 2.0 yarns / 50 mm to 4.0 yarns / 50 mm, so that the processability of the cord fabric 1 during calendering and slitting can be improved. As a result, the width of the cord fabric 1 and the tape 10 can be stabilized, and the number of warp yarns 2 included in the tape 10 can be suppressed from being uneven.

[0033] Here, if the weft yarn 3 is a high elongation yarn, the weft yarn 3 is easy to stretch, so the width of the cord fabric 1 is easy to change during calendering. If the fineness of the weft yarn 3 is less than 150 dtex, the weft yarn 3 is easy to break, so it is difficult to arrange it at equal intervals on the warp yarn 2. On the contrary, if it is greater than 350 dtex, the strength is too high and the weft yarn 3 is difficult to cut. In addition, if the density of the weft yarn 3 is less than 2.0 yarns / 50 mm, the restraining force in the width direction of the cord fabric 1 becomes small, so the width of the cord fabric 1 tends to be excessively widened during calendering. On the contrary, if it is greater than 4.0 yarns / 50 mm, the restraining force in the width direction of the cord fabric 1 becomes large, so the width of the cord fabric 1 tends to be excessively narrowed during calendering.

[0034] The breaking elongation of the weft yarn 3 is preferably 10% or less. This can improve the processability of the cord fabric 1 during calendering and slitting. If the breaking elongation of the weft yarn 3 is greater than 10%, the width of the cord fabric 1 is likely to vary during calendering.

[0035] Generally, the above-mentioned cord fabric 1 is subjected to an impregnation treatment using an adhesive composition before being rubber-coated. First, the cord fabric 1 is immersed in a treatment liquid of an adhesive composition containing an epoxy compound, so that the adhesive composition containing an epoxy compound is attached to the warp yarn 2 and the weft yarn 3. After the cord fabric 1 to which the adhesive composition containing an epoxy compound is attached is dried in a drying zone at a temperature range of, for example, 100°C to 150°C, the warp yarn 2 is heat-treated in a heat setting zone at a temperature range of, for example, 235°C to 250°C while applying a tension of, for example, 0.15g / dtex to 0.60g / dtex.

[0036] Next, the cord fabric 1 is immersed in a treatment liquid of an adhesive composition composed of resorcinol formalin latex (RFL) to attach the RFL adhesive composition to the warp yarns 2 and the weft yarns 3. After the cord fabric 1 to which the RFL adhesive composition is attached is dried in a drying zone in a temperature range of, for example, 100°C to 150°C, the warp yarns 2 are heat-treated in a normalizing zone in a temperature range of, for example, 225°C to 255°C while applying a tension of, for example, 0.15g / dtex to 0.35g / dtex. In addition, an adhesive composition from which resorcinol and formalin are removed may be used instead of the RFL adhesive composition.

[0037] The cord fabric 1 using spun cotton yarn as the weft yarn 3 is particularly effective when subjected to an impregnation treatment with an adhesive composition containing an epoxy compound. That is, the adhesive composition containing an epoxy compound is effective as an adhesive treatment agent for the warp yarn 2, but the impregnation treatment with the adhesive composition containing an epoxy compound will reach a high temperature, so if the weft yarn 3 is an undrawn yarn of polyethylene terephthalate fiber or a yarn of a core-sheath structure with polyethylene terephthalate fiber as a core and cotton as a sheath, it is easily affected by heat. In contrast, when using spun cotton yarn as the weft yarn 3, it is not easily affected by heat even if it is impregnated with an adhesive composition containing an epoxy compound.

[0038] The tire cord fabric of the present invention can be used for reinforcing layers of a pneumatic tire, such as a carcass layer, a belt cover layer, and a sidewall reinforcing layer, and is preferably used for a belt cover layer in particular.

[0039] Figure 4 1 is a diagram showing a pneumatic tire according to an embodiment of the present invention. Figure 1 As shown, the pneumatic tire of this embodiment includes: a tread portion 11 extending in a ring shape along the tire circumferential direction; a pair of sidewall portions 12, 12 arranged on both sides of the tread portion 11; and a pair of bead portions 13, 13 arranged on the inner side of these sidewall portions 12 in the tire radial direction.

[0040] A carcass layer 14 is provided between a pair of bead portions 13, 13. The carcass layer 14 includes a plurality of reinforcing cords extending in the tire radial direction and folded back from the inside to the outside of the tire around a bead core 15 disposed at each bead portion 13. A bead filler 16 formed of a rubber composition and having a triangular cross-section is disposed on the outer periphery of the bead core 15.

[0041] On the other hand, a plurality of belt layers 17 are buried on the outer peripheral side of the carcass layer 14 at the tread portion 11. These belt layers 17 include a plurality of reinforcing cords inclined relative to the tire circumferential direction, and are arranged in a manner that the reinforcing cords intersect each other between the layers. In the belt layer 17, the inclination angle of the reinforcing cords relative to the tire circumferential direction is set, for example, in the range of 10° to 40°. As the reinforcing cords of the belt layer 17, steel cords are preferably used. For the purpose of improving high-speed durability, at least one belt covering layer 18 is arranged on the outer peripheral side of the belt layer 17, in which the reinforcing cords are arranged at an angle of, for example, less than 5° relative to the tire circumferential direction.

[0042] like Figure 5 As shown, the belt cover layer 18 is formed by spirally winding a strip material 10 of a rubber-coated cord fabric 1 on the outer peripheral side of the belt layer 17 in the tire circumferential direction. The width of the strip material 10 is, for example, 5 mm to 20 mm. By providing such a belt cover layer 18, it is possible to prevent the belt layer 17 from bulging when the tire rolls, and as a result, it is possible to improve the high-speed durability of the pneumatic tire and suppress road noise.

[0043] When the cord fabric 1 constructed as described above is used as the starting material of the belt covering layer 18, the processability of the cord fabric 1 during calendering and slitting is improved, so that the width of the cord fabric 1 and the belt material 10 can be stabilized, and the number of warp yarns included in the belt material 10 can be suppressed from being uneven. As a result, the uniformity of the pneumatic tire having the belt covering layer 18 formed using the belt material 10 can be improved.

[0044] Example

[0045] A tire cord fabric having a plurality of warp yarns arranged in parallel and weft yarns inserted crosswise at a low density relative to the warp yarns was produced, wherein the material of the warp yarns, the material of the weft yarns, the elongation at break of the weft yarns, the fineness of the weft yarns, and the density of the weft yarns were set as shown in Table 1 in the prior art examples, embodiments 1 to 4, and comparison examples 1 to 4.

[0046] The tire cord fabric was subjected to a first dipping treatment using an adhesive composition containing an epoxy compound and a second dipping treatment using an adhesive composition composed of resorcinol formalin latex (RFL). As the warp yarn of the tire cord fabric, a cord formed by twisting a plurality of primary twist yarns composed of polyethylene terephthalate (PET) fibers together, or a mixed cord formed by twisting primary twist yarns composed of aramid fibers and primary twist yarns composed of nylon fibers together, was used. As the weft yarn of the tire cord fabric, a yarn having a core-sheath structure with polyethylene terephthalate fibers as a core and cotton as a sheath, or a cotton spun yarn was used.

[0047] The tire cord fabrics of the above-mentioned Conventional Example, Examples 1 to 4, and Comparative Examples 1 to 4 were evaluated for processability during calendering and processability during slitting by the following methods. The results are collectively shown in Table 1.

[0048] Processability during calendering:

[0049] In the calendering process of the rubber-coated cord fabric, the width variation of the rubber-coated calendered material (cord fabric coated with rubber) was measured over the entire length. Regarding the evaluation results, "×" indicates that the width variation of the calendered material exceeds 10 mm, "△" indicates that the width variation is less than 10 mm and exceeds 5 mm, and "○" indicates that the width variation is less than 5 mm.

[0050] Processability during slitting:

[0051] In the process of slitting the rolled material into a certain width, the width variation of the strip after slitting was measured over the entire length. The evaluation results were marked with "×" to indicate that the width variation of the strip exceeded 2 mm, "△" to indicate that the width variation was less than 2 mm and more than 1 mm, and "○" to indicate that the width variation was less than 1 mm.

[0052] [Table 1]

[0053]

[0054] According to Table 1, the tire cord fabric of the conventional example has a high elongation yarn in the weft, so the calendering width fluctuates and the slitting width is unstable. In contrast, the tire cord fabrics of Examples 1 to 4 have a stable calendering width and a stable slitting width because the weft yarn is a cotton yarn. On the other hand, the tire cord fabric of Comparative Example 1 has a too thin weft, so the weft yarn is easily broken during calendering, and as a result, the warp yarn cannot be constrained at equal intervals, and slitting is also difficult. The tire cord fabric of Comparative Example 2 has a too thick weft, so it is difficult to slit due to excessive strength. The tire cord fabric of Comparative Example 3 has a too low density of weft yarn, so the restraining force in the width direction of the cord fabric becomes small, the calendering width becomes wide, and the slitting width is also unstable. The tire cord fabric of Comparative Example 4 has a too high density of weft yarn, so the restraining force in the width direction of the cord fabric becomes large, the calendering width becomes narrow, and the slitting width is also unstable.

[0055] Next, when manufacturing an inflatable tire having a carcass layer spanned between a pair of bead portions, a belt layer arranged on the outer circumferential side of the carcass layer, and a belt covering layer arranged on the outer circumferential side of the belt layer, the belt covering layer is formed by spirally winding a belt material obtained from the tire cord fabric of the prior art examples, Examples 1 to 4, and Comparative Examples 1 to 4 along the circumferential direction of the tire.

[0056] The pneumatic tires of the prior art examples, Examples 1 to 4, and Comparative Examples 1 to 4 were evaluated for the variation in the number of warp yarns in the belt material and the tire uniformity by the following methods. The results are shown in Table 2.

[0057] Uneven number of warp yarns in the tape:

[0058] The number of warp yarns in the belt used for 10 tires was measured to find the number of variations from the reference value. For example, when the reference value of the number of warp yarns was 8, the evaluation result was set as "±1" if there was a belt with 7 or 9 warp yarns.

[0059] Tire uniformity:

[0060] Each test tire was mounted on a uniformity tester, and the conicity of 10 test tires was measured to find the standard deviation σ. The evaluation results were expressed as an index with the reciprocal of the standard deviation σ set to 100. The larger the index value, the better the uniformity of the tire.

[0061] [Table 2]

[0062]

[0063] As can be seen from Table 2, in the tire of the conventional example, since the weft yarn is a high elongation yarn, the calendering width fluctuates, and the number of warp yarns in the tape is uneven. In contrast, in the tires of Examples 1 to 4, since the weft yarn is a cotton spun yarn, the calendering width is stable, the slitting width is also stable, and the number of warp yarns in the tape is constant, resulting in improved uniformity. On the other hand, in Comparative Example 1, since the weft yarn is too thin, the weft yarn is easy to break during calendering and difficult to slit. Therefore, in Comparative Example 1, the tape cannot be provided for tire manufacturing. In the tire of Comparative Example 2, since the weft yarn is too thick, the weft yarn is difficult to break during slitting, wrinkles are generated in the width direction of the calendered material, and the number of warp yarns in the tape is uneven, resulting in deterioration of uniformity. In the tire of Comparative Example 3, since the density of the weft yarn is too low, the restraining force in the width direction of the cord fabric becomes small, the calendering width becomes wide, and the slitting width is also unstable, resulting in deterioration of uniformity. In the tire of Comparative Example 4, since the density of the weft yarns was too high, the restraining force in the width direction of the cord fabric became large, the calendering width became narrow, and the slitting width became unstable, resulting in deterioration in uniformity.

[0064] Description of Reference Numerals

[0065] 1 Cord fabric

[0066] 2 Warp

[0067] 3 Weft

[0068] 4 Covering rubber

[0069] 10 Strip

[0070] 11 Tread

[0071] 12 Sidewall

[0072] 13 Bead section

[0073] 14 Carcass layer

[0074] 15 Bead core

[0075] 16 Bead filler

[0076] 17 Belt

[0077] 18 Belt Cover

Claims

1. A tire cord fabric comprising a plurality of warp yarns arranged in parallel and weft yarns inserted crosswise with respect to the warp yarns at a low density, wherein the tire cord fabric is characterized in that: The warp yarn is an organic fiber cord including polyethylene terephthalate fiber or aramid fiber, and the weft yarn is a cotton spun yarn. The fineness of the weft yarn is in the range of 150 dtex to 350 dtex, and the density of the weft yarn is in the range of 2.0 yarns / 50 mm to 4.0 yarns / 50 mm.

2. The tire cord fabric according to claim 1, characterized in that: The warp yarns and the weft yarns are impregnated with an adhesive composition containing an epoxy compound.

3. The tire cord fabric according to claim 1 or 2, characterized in that: The breaking elongation of the weft yarn is less than 10%.

4. The tire cord fabric according to any one of claims 1 to 3, characterized in that: The warp yarns have a two-twisted structure or a three-twisted structure.

5. A pneumatic tire comprising: a carcass layer spanned between a pair of bead portions; a belt layer arranged on the outer peripheral side of the carcass layer; and a belt covering layer arranged on the outer peripheral side of the belt layer and formed by spirally winding a belt of a cord fabric covered with rubber along the tire circumferential direction, wherein the pneumatic tire is characterized in that: The cord fabric includes a plurality of warp yarns arranged in parallel, and weft yarns cross-inserted at a low density relative to the warp yarns, the warp yarns are organic fiber cords containing polyethylene terephthalate fibers or aromatic polyamide fibers, the weft yarns are cotton spun yarns, the fineness of the weft yarns is in the range of 150 dtex to 350 dtex, and the density of the weft yarns is in the range of 2.0 yarns / 50 mm to 4.0 yarns / 50 mm.

6. The pneumatic tire according to claim 5, characterized in that: The warp yarns and the weft yarns are coated with an adhesive composition containing an epoxy compound.

7. The pneumatic tire according to claim 5 or 6, characterized in that: The breaking elongation of the weft yarn is less than 10%.

8. The pneumatic tire according to any one of claims 5 to 7, characterized in that: The warp yarns have a two-twisted structure or a three-twisted structure.

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