PNEUMATIC TIRE

Abstract

The present invention relates to a pneumatic tire comprising: a tread; one pair of shoulders respectively continued to both sides of the tread with the tread part as a center; one pair of sidewalls respectively continued to the shoulders; one pair of beads respectively continued to the sidewalls; a body ply formed on the inner sides of the tread, shoulders, sidewalls and beads; a belt and a cap ply part sequentially stacked between the inner side of the tread and the body ply; and an inner liner bonded to the inner side of the body ply, wherein in the inner liner, a sheet including a rubber component is positioned at the part of the body ply corresponding to the shoulders and the sidewalls, and a polymer film including a polyamide-based component is positioned at the part of the body ply corresponding to the tread.

Claims

1. A pneumatic tire comprising: a tread one pair of shoulders respectively continued to both sides of the tread with the tread as a center; one pair of sidewalls respectively continued to the shoulders; one pair of beads respectively continued to the sidewalls; a body ply formed on the inner side of the tread, shoulders, sidewalls and beads; a belt and a cap ply sequentially stacked between the inner side of the tread and the body ply; and an inner liner bonded to the inner side of the body ply, wherein in the inner liner, a sheet including a rubber component is positioned at the part of the body ply corresponding to the shoulders and the sidewalls, and a polymer film including a polyamide-based component is positioned at the part of the body ply corresponding to the tread.

2. The pneumatic tire according to claim 1, wherein on the basis of the cross section of the tread in the width direction, the polymer film including a polyamide-based component contacts with the part of the body ply corresponding to the tread, and the sheet including a rubber component is stacked such that it contacts with the part of the body ply corresponding to the shoulders and the sidewalls, and one side of the polymer film including a polyamide-based component of the inward direction of the pneumatic tire.

3. The pneumatic tire according to claim 1, wherein on the basis of the cross section of the tread in the width direction, the sheet including a rubber component contacts with the part of the body ply corresponding to the tread, shoulders and sidewalls, and the polymer film including a polyamide-based component is stacked on the opposite side of one side of the sheet including a rubber component that contacts with the part of the body ply corresponding to the tread.

4. The pneumatic tire according to claim 1, wherein on the basis of the cross section of the tread in the width direction, sheets including rubber components are respectively bonded to both ends of the polymer film including a polyamide-based component.

5. The pneumatic tire according to claim 4, wherein on the basis of the cross section of the tread in the width direction, the overlapped length between the end of the polymer film including a polyamide-based component and the sheet including a rubber component is 10 mm to 60 mm.

6. The pneumatic tire according to claim 1, wherein the sheet including a rubber component includes one or more kinds selected from the group consisting of synthetic rubber including butyl rubber or halobutyl rubber, and natural rubber.

7. The pneumatic tire according to claim 1, wherein the thickness of the sheet including a rubber component is 0.1 mm to 5 mm.

8. The pneumatic tire according to claim 1, wherein the polymer film including a polyamide-based component includes one or more compounds selected from the group consisting of polyamide-based resin; and copolymer including polyamide-based segments and polyether-based segments.

9. The pneumatic tire according to claim 8, wherein the content of the polyether-based segments in the polymer film including a polyamide-based component is 2 wt % to 40 wt %.

10. The pneumatic tire according to claim 8, wherein the polymer film including a polyamide-based component includes the polyamide-based resin and copolymer at a weight ratio of 6:4 to 3:7.

11. The pneumatic tire according to claim 8, wherein the polymer film including a polyamide-based component has a thickness of 2 m to 400 m.

12. The pneumatic tire according to claim 1, wherein the polymer film including a polyamide-based component includes one or more compounds selected from the group consisting of olefin-based polymer, olefin-based copolymer, and olefin-based polymer or copolymer grafted with dicarboxylic acid or acid anhydride thereof.

13. The pneumatic tire according to claim 1, wherein the polymer film including a polyamide-based component is bonded to the inner side of the body ply by an adhesion layer comprising a resorcinol-formalin-latex(RFL)-based adhesive, and having a thickness of 0.1 to 20 m.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0102] FIG. 1 schematically shows the structure of a pneumatic tire.

[0103] FIG. 2 schematically shows the cross-section of a pneumatic tire according to one embodiment of the present invention.

[0104] FIG. 3 schematically shows the cross-section of a pneumatic tire according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0105] Hereinafter, the present invention will be explained in detail through the following examples. However, these examples are presented only as the illustrations of the present invention, and the scope of the present invention is not limited thereby.

PREPARATION EXAMPLE

Preparation Example 1. Preparation of a Polymer Film Including a Polyamide-Based Component

[0106] (1) Preparation of a substrate film Polyamide-based resin with a relative viscosity of 3.3 (sulfuric acid 96% solution), prepared from -caprolactam (nylon 6), copolymer resin having a weight average molecular weight of about 105,000 (including 25 wt % of polyether-based segments having a polytetramethylene oxide main chain, and 75 wt % of polyamide-based segments derived from -caprolactam), and copolymer resin having a weight average molecular weight of about 115,000 (synthesized using 25 wt % of polyether-based segments having a poly(iso-propylene)oxide main chain with an amine end group, and 75 wt % of polyamide-based segments derived from -caprolactam) were mixed at a weight ratio of 5:2.5:2.5, and a crosslinking agent of styrene 2-isopropenyl-2-oxazoline copolymer and a heat resistant agent [a mixture of copper iodide and potassium iodidecontent of Cu in the mixture is 7 wt %] were added thereto, thus preparing a mixture for preparing a polymer film including a polyamide-based component. The content of the crosslinking agent in the mixture was 0.5 wt %, and the content of the heat resistant agent was 0.3 wt %.

[0107] And, the mixture was extruded while maintaining uniform flow of molten resin, through a T-type die(die gap1.0 mm) at 260 C., and the molten resin was cooled and solidified to a film with a uniform thickness, using an air knife, on the surface of a cooling roll adjusted to 25 C. And, an undrawn polymer film including a polyamide-based component with a thickness of 100 um was obtained without passing through drawing and heat treatment sections at the velocity of 15 m/min.

[0108] (2) Formation of an Adhesion Layer

[0109] Resorcinol and formaldehyde were mixed at a mole ratio of 1:2, and then, the mixture was subjected to a condensation reaction to obtain the condensation product of resorcinol and formaldehyde. 12 wt % of the condensation product of resorcinol and formaldehyde and 88 wt % of styrene/butadiene-1,3/vinylpyridine latex were mixed to obtain resorcinol-formalin-latex(RFL)-based adhesive of the concentration of 20%. And, the resorcinol-formalin-latex(RFL)-based adhesive was coated on both sides of the undrawn polymer film including a polyamide-based component using a gravure coater, and dried and reacted at 150 C. for 1 minute to form an adhesion layers respectively with a thickness of 2 m on both sides.

Preparation Example 2. Preparation of a Film Using Butyl Rubber and Natural Rubber(NR)

[0110] 100 parts by weight of raw material rubber including 60 wt % of butyl rubber and 40 wt % of natural rubber, 30 parts by weight of carbon black, 3 parts by weight of paraffin oil, 2 parts by weight of zinc oxide, 1 part by weight of stearic acid, 2 parts by weight of an anti-ageing agent, 1 part by weight of sulfur, and 1 part by weight of a vulcanization accelerator were put in a mixer, and the mixture was vulcanized at 160 C. for 20 minutes, thus preparing a rubber film with a uniform thickness.

Example: Preparation of a Pneumatic Tire

Example 1

[0111] Using the polymer film prepared in Preparation Example 1 and the rubber film prepared in Preparation Example 2, a 205R/75R15 standard tire was manufactured, and evaluated. As a cord included in a body ply, a 1300De/2ply HMLS tire cord was applied, and as a belt, a steel cord was used, and as a cap ply, a N66 840De'/2ply product was applied.

[0112] Specifically, the rubber film prepared in Preparation Example 2 (thickness: 1.00 mm) was covered on a tire molding drum, and the polymer film including a polyamide-based component of Preparation Example 1 was overlapped on the part of a body ply corresponding to a tread, and then, the overlapped part was fixed with a tie gum having a thickness of 1 mm so as to fix the polymer film.

[0113] And, on the inner liner film, rubber for a body ply was stacked, rubber layers for the formations of a bead wire; a belt; a cap ply; and a tread, shoulders and sidewalls were sequentially formed to manufacture a green tire.

[0114] The manufactured green tire was put in a mold, and a tire was manufactured through vulcanization at 160 C. for 30 minutes.

Example 2

[0115] A pneumatic tire was manufactured by the same method as Example 1, except that the thickness of the rubber film prepared in Preparation Example 2 was changed to 0.60 mm.

Example 3

[0116] A pneumatic tire was manufactured by the same method as Example 1, except that 1) the thickness of the rubber film prepared in Preparation Example 2 was changed to 1.2 mm, and 2) the end of the polymer film including a polyamide-based component of Preparation Example 1 and the end of the rubber film prepared in Preparation Example 2 were overlapped by 20 mm to form a splice.

Example 4

[0117] A pneumatic tire was manufactured by the same method as Example 1, except that 1) the thickness of the rubber film prepared in Preparation Example 2 was changed to 1.2 mm, and 2) the end of the polymer film including a polyamide-based component of Preparation Example 1 and the end of the rubber film prepared in Preparation Example 2 were overlapped by 10 mm to form a splice.

Example 5

[0118] A pneumatic tire was manufactured by the same method as Example 1, except that 1) the thickness of the rubber film prepared in Preparation Example 2 was changed to 1.2 mm, and 2) the end of the polymer film including a polyamide-based component of Preparation Example 1 and the end of the rubber film prepared in Preparation Example 2 were overlapped by 5 mm to form a splice.

Comparative Example 1

[0119] A pneumatic tire was manufactured by the same method as Example 1, except that the rubber film prepared in Preparation Example 2 (thickness 1.2 mm) was used alone.

Comparative Example 2

[0120] A pneumatic tire was manufactured by the same method as Example 1, except that the rubber film prepared in Preparation Example 2 (thickness 0.60 mm) was used alone.

Experimental Example: Measurement of the Performances of Pneumatic Tires

[0121] 1. Measurement of Durability

[0122] Using a FMVSS139 tire durability measurement method, while increasing a load, the durability of a tire was tested and evaluated. Such a durability measurement was conducted by two methods of Endurance Test wherein a load is increased by a step load method, and High Speed Test wherein a speed is increased, and with the result of Comparative Example 1 as 100, the results of Examples and Comparative Examples were compared and evaluated.

[0123] 2. Measurement of Internal Pressure Maintenance Performance

[0124] Using the tire inner liner films of Examples and Comparative Examples, 205R/65R16 tires were manufactured. And, the initial internal pressures of the manufactured tires were measured by the method of ASTM F1112-06, and the tire internal pressures were measured at a temperature of 21 C. under a pressure of 101.3 kPa for 120 days. By the following Calculation Formula, internal pressure retentions(IPR) were measured, compared and evaluated.

Internal Pressure Retention (%)=internal pressure after 120 days/initial internal pressure*100[Calculation Formula]

[0125] 3. Measurement of Rolling Resistance (RR)

[0126] The rolling resistances of the 205R/65R16 tires manufactured using the tire inner liner films of Examples and Comparative Examples were measured under conditions of an internal pressure of 210 kPa and a load of 490 kgf, by the method of SAE J2452/ISO 285580. Here, with the rolling resistance measured in Comparative Example 1 as 100, the rates to the rolling resistance of Comparative Example 1 were measured and evaluated.

[0127] 4. Measurement of the Weight of a Tire

[0128] The weights of the finished tires were measured, and the weights of the tires obtained in Examples and Comparative Examples were compared.

TABLE-US-00001 TABLE 1 Evaluation results of tires Example Example Example comparative Comparative 3 4 5: Example Example Example Example overlap overlap overlap 1: 2: 1 2 20 mm 10 mm 5 mm NR/IR NR/IIR Thickness of 1.00 0.62 1.20 0.62 1.20 1.20 0.62 rubber inner liner (mm) Measurement 101 98 99 98 82 100 98 of durability Endurance TEST (%) Measurement 103 100 101 100 90 100 99 of durability High Speed Test (%) Internal 2.6 2.0 2.6 2.5 2.0 2.5 1.8 pressure before running (bar) Internal 93.0 89.2 90.5 87.4 85.2 88.5 81.6 pressure retention after 120 days (%) Rolling 98,2 98.5 97.2 97.3 97.5 100 99.2 resistance (%) Tire weight 10.67 10.34 10.45 10.14 10.41 10.80 10.31 (kg)

[0129] As shown in Table 1, it was confirmed that the pneumatic tires including the inner liner films of Examples 1 to 5 may lead to weight decrease of about 0.13 kg/one tire to 0.66 kg/one tire, compared to the tire of Comparative Example 1, and they have relatively low rolling resistances compared to the inner liners of Comparative Examples 1 to 2.

[0130] And, it was confirmed that the pneumatic tires including the inner liner films of Examples 1 to 5 can secure internal pressure retention equivalent to or more excellent than that of Comparative Example 1, due to excellent air barrier, and particularly, have far superior internal pressure retention after 120 days.

[0131] And, in the pneumatic tires including the inner liner films of Examples 1 to 5, cracks were not generated inside even during running of an automobile or under severe strain conditions of tires, and thus, they exhibited durability equivalent to or more excellent than those of Comparative Examples 1 to 2 in Endurance Test.

[0132] And, each pneumatic tire including the inner liner films of Examples 1 to 5, although the thickness of the previous inner liner made of rubber(butyl/natural rubber, etc.) was decreased to about half, have a durability value equivalent to the tire using any inner liner of Comparative Examples 1 and 2, and simultaneously, exhibited very excellent internal pressure retention.

EXPLANATION TO SYMBOLS

[0133] 1: Tread [0134] 11: Tread rubber [0135] 2: Shoulder [0136] 3: Sidewall [0137] 4: Cap ply [0138] 5: Belt [0139] 6: Body ply [0140] 7: Inner liner [0141] 8: APEX [0142] 9: Bead [0143] 91: Bead core [0144] 92: Bead filler [0145] 12: Side Rubber [0146] 13: Cushion rubber