Film for tire inner liner, method for manufacturing film for tire inner liner, pneumatic tire, and method for manufacturing pneumatic tire

Abstract

This disclosure relates to a film for a tire inner liner film that may exhibit uniform excellent physical properties over all directions when applied to a tire, and may secure excellent durability and fatigue resistance in a tire manufacturing process or in an automobile running process, a method for manufacturing the film for a tire inner liner, a pneumatic tire using the tire inner liner film, and a method for manufacturing the pneumatic tire using the tire inner liner film.

Claims

1. A film for a tire inner liner comprising a base film that is drawn or oriented in a first direction, and is in the undrawn state in a second direction perpendicular to the first direction, wherein the first direction is set parallel to the axial direction of a tire forming drum for manufacturing a pneumatic tire, and a strength ratio of the first direction to the second direction of the base film is 1.1:1 to 2:1, wherein the base film comprises (i) a copolymer comprising polyamide-based segments and polyether-based segments, or (ii) a resin mixture of a polymer comprising polyamide-based segments and a polymer comprising polyether-based segments, and the content of the polyether-based segments of the copolymer or the content of the polymer comprising polyether-based segments is 5 wt % to 50 wt % based on the total weight of the base film.

2. The film for a tire inner liner according to claim 1, wherein the first direction is identical to the machine direction (MD) of the base film, and the second direction is identical to the transverse direction (TD) of the base film.

3. The film for a tire inner liner according to claim 2, wherein the length of the base film in the second direction is 1000 mm or more.

4. The film for a tire inner liner according to claim 1, wherein the film is drawn 5% to 50% in the first direction of the base film, and further comprising an adhesive layer formed on at least one side of the base film.

5. The film for a tire inner liner according to claim 4, wherein the first direction is identical to the transverse direction (TD) of the base film, and the second direction is identical to the machine direction (MD) of the base film.

6. The film for a tire inner liner according to claim 5, wherein the length of the base film in the first direction is 1000 mm or less.

7. The film for a tire inner liner according to claim 1, wherein the copolymer comprises polyamide-based segments and polyether-based segments at a weight ratio of 7:3 to 3:7.

8. The film for a tire inner liner according to claim 1, wherein the resin mixture comprises the polymer comprising polyamide-based segments and the polymer comprising polyether-based segments at a weight ratio of 7:3 to 3:7.

9. The film for a tire inner liner according to claim 1, wherein the base film further comprises a polyamide-based resin having relative viscosity (96% sulfuric acid solution) of 3.0 to 4.0.

10. The film for a tire inner liner according to claim 9, wherein the base film comprises the polyamide-based resin and the (i) copolymer or the (ii) resin mixture at a weight ratio of 7:3 to 3:7.

11. The film for a tire inner liner according to claim 1, further comprising an adhesive layer that is formed on at least one side of the base film and comprises a resorcinol-formalin-latex (RFL)-based adhesive.

12. A method for manufacturing the film for a tire inner liner of claim 1, comprising: melting and extruding a raw material for a base film to form a base film having a width of 1000 mm or more in the transverse direction (TD); and orienting the base film such that total draft in the machine direction becomes 6 to 20.

13. The method for manufacturing a film for a tire inner liner according to claim 12, wherein the total draft in the machine direction is a value obtained by multiplying a melt draft ratio in an extrusion die of the following Equation 1 and a draw ratio after the extrusion die:
melt draft ratio in an extrusion die=speed of a casting roll(m/min)/discharge speed of raw material in a die(m/min).[Equation 1]

14. The method for manufacturing a film for a tire inner liner according to claim 13, comprising drawing such that the draw ratio after the extrusion die becomes 1.05 to 1.5.

15. The method for manufacturing a film for a tire inner liner according to claim 12, wherein the step of melting and extruding raw material for a base film to form a base film having a width of 1000 mm or more in the transverse direction (TD) comprises melting and extruding the raw material for a base film in an extrusion die having a die gap of 0.3 to 1.5 mm.

16. The method for manufacturing a film for a tire inner liner according to claim 12, wherein the step of forming a base film comprises melting and extruding raw material for a base film comprising (i) a copolymer comprising polyamide-based segments and polyether-based segments, or (ii) a resin mixture of a polymer comprising polyamide-based segments and a polymer comprising polyether-based segments at 230 C. to 300 C. to form a film having a thickness of 30 m to 300 m, and the content of the polyether-based segments or the content of the polymer comprising polyether-based segments of the copolymer is 5 wt % to 50 wt %, based on the total weight of the base film.

17. The method for manufacturing a film for a tire inner liner according to claim 16, wherein the raw material for a base film further comprises a polyamide-based resin.

18. The method for manufacturing a film for a tire inner liner according to claim 17, wherein the raw material for a base film comprises the polyamide-based resin and the copolymer or the mixture at a weight ratio of 7:3 to 3:7.

19. The method for manufacturing a film for a tire inner liner according to claim 16, wherein the copolymer comprises the polyamide-based segments and the polyether-based segments at a weight ratio of 7:3 to 3:7, and the resin mixture comprises the polymer comprising polyamide-based segments and the polymer comprising polyether-based segments at a weight ratio of 7:3 to 3:7.

20. The method for manufacturing a film for a tire inner liner according to claim 12, further comprising coating a resorcinol-formalin-latex (RFL)-based adhesive on at least one side of the base film layer to a thickness of 0.1 m to 20 m to form an adhesive layer.

21. A pneumatic tire manufactured using the film for a tire inner liner of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically shows the structure of a tire.

(2) FIG. 2 shows the radial direction and the circumferential direction of a pneumatic tire.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(3) Hereinafter, the present invention will be explained in detail with reference to the following examples. However, these examples are only to illustrate the invention and the scope of the invention is not limited thereto.

EXAMPLE

Example: Manufacture of a Film for a Tire Inner Liner and a Pneumatic Tire

Example 1

(1) Manufacturing of a Base Film

(4) 35 wt % of a nylon 6 resin having a relative viscosity (96% sulfuric acid solution) of 3.3 and 65 wt % of a copolymer resin having a relative weight average molecular weight of 145,000 (including 50 wt % of polyamide-based repeat units and 50 wt % of polyether-based repeat units) were mixed, and the supplied mixture was extruded through a T-type die (die gap1.0 mm) having a width of 2000 mm at a temperature of 260 C. while maintaining uniform flow of melted resin. The extruded melted resin was cooled and solidified to a film with a uniform thickness [average thickness: 100 m] using an air knife on the surface of a cooling roll that was controlled to 25 C.

(2) Coating of Adhesive and Drawing in TD

(5) Resorcinol and formaldehyde were mixed at a mole ratio of 1:2, and then condensed to obtain a condensate of resorcinol and formaldehyde. 12 wt % of the condensate of resorcinol and formaldehyde and 88 wt % of styrene/butadiene-1,3/vinylpyridine were mixed to obtain a resorcinol-formalin-latex (RFL)-based adhesive with a concentration of 20%.

(6) The resorcinol-formalin-latex (RFL)-based adhesive was coated on the base film to a thickness of 1 m using a gravure coater.

(7) Subsequently, the base film on which adhesive was coated was drawn in the transverse direction (TD) in a hot-air oven including a caterpillar rail equipped with a mechanical grip. Specifically, the hot-air oven consisted of three sections, wherein the temperature of the first section was set to 110 C., the temperature of the second section was set to 130 C., and the temperature of the third section was set to 150 C., and in the second section, the base film was drawn 20% in the transverse direction (TD) using a mechanical grip.

(8) The speed of a winder that wound the base film on which an adhesive layer was coated was adjusted to maintain a residence time of the base film in the hot-air oven at about 60 seconds, and heat treatment of the adhesive layer and drawing in the transverse direction (TD) were completed.

Example 2

(9) A film for a tire inner liner was manufactured by the same method as Example 1, except for the following processes (1) and (2).

(10) (1) The temperature in the first section of the hot air oven was set to 100 C., the temperature of the second section was set to 130 C., the temperature of the third section was set to 140 C., and in the second section of the hot air oven, the base film was drawn 40% in the transverse direction (TD) using a mechanical grip.

(11) (2) The speed of a winder that wound the base film on which an adhesive layer was coated was adjusted to maintain residence time of the base film in the hot-air oven at about 120 seconds, and heat treatment of the adhesive layer and drawing in the transverse direction (TD) were completed.

Example 3

(12) A film for a tire inner liner was manufactured by the same method as Example 1, except for the following processes (1) to (3).

(13) (1) The die gap of the t-type die was set to 0.7 mm.

(14) (2) The temperature of the first section of the hot air oven was set to 120 C., the temperature of the second section was set to 120 C., and the temperature of the third section was set to 150 C., and in the first section and the second section of the hot air oven, the base film was respectively drawn 5% in the transverse direction (TD) using a mechanical grip to a draw total of 10%.

(15) (3) The speed of a winder that wound the base film on which an adhesive layer was coated was adjusted to maintain residence time of the base film in the hot-air oven at about 120 seconds, and heat treatment of the adhesive layer and drawing in the transverse direction (TD) were completed.

Example 4

(16) A film for a tire inner liner was manufactured by the same method as Example 1, except for the following processes (1) to (3).

(17) (1) The die gap of the t-type die was set to 0.7 mm.

(18) (2) The temperature of the first section of the hot air oven was set to 110 C., the temperature of the second section was set to 130 C., and the temperature of the third section was set to 140 C., and in the first section to the third section of the hot air oven, the base film was respectively drawn 5% in the transverse direction (TD) using a mechanical grip to a draw total of 15%.

(19) (3) The speed of a winder that wound the base film on which an adhesive layer was coated was adjusted to maintain a residence time of the base film in the hot-air oven at about 150 seconds, and heat treatment of the adhesive layer and drawing in the transverse direction (TD) were completed.

Example 5

(1) Manufacturing of a Base Film

(20) A base film having a uniform thickness [average thickness: 100 m] was obtained by the same method as Example 1.

(2) Coating of Adhesive and Drawing in TD

(21) 1) Drawing in TD

(22) The base film was drawn in the transverse direction (TD) in a first hot-air oven including a caterpillar rail equipped with a mechanical grip. The first hot-air oven consisted of three sections, wherein the temperatures of the first to third sections were all set to 110 C., the base film was drawn 20% in the transverse direction in the second section, and the drawn base film was stabilized in the third section. The residence time of the base film in the first hot air oven was maintained at about 30 seconds.

(23) 2) Coating of Adhesive

(24) On the base film obtained in the first drawing step, a resorcinol-formalin-latex (RFL)-based adhesive was coated to a thickness of 1 m using a gravure coater by the same method as Example 1.

(25) Further, the base film on which the RFL-based adhesive was coated was dried and heat treated in a second hot air oven including a caterpillar rail equipped with a mechanical grip to complete heat treatment of the adhesive layer.

(26) The second hot air oven consisted of three sections, wherein the temperature of the first section was set to 130 C., the temperature of the second section was set to 140 C., and the temperature of the third section was set to 150 C. The speed of a winder that wound the base film on which an adhesive layer was coated was adjusted to maintain residence time of the base film in the hot-air oven at about 30 seconds, and heat treatment of the adhesive layer was completed.

Example 6

(27) A film for a tire inner liner was manufactured by the same method as Example 1, except that a compounded substance including 50 wt % of a polyamide-based polymer and 50 wt % of a polyether-based polymer was used instead of the copolymer having an absolute weight average molecular weight of 145,000.

Example 7

(1) Manufacturing of a Base Film

(28) 35 wt % of nylon 6 resin having a relative viscosity (96% sulfuric acid solution) of 3.3 and 65 wt % of a copolymer resin having a relative weight average molecular weight of 145,000 (including 50 wt % of polyamide-based repeat units and 50 wt % of polyether-based repeat units) were mixed, and the supplied mixture was extruded through a t-type die (die gap1.0 mm) having a width of 1800 mm at a temperature of 260 C. while maintaining uniform flow of melted resin.

(29) Herein, the discharge amount of raw material from the die was set to 1550 g/min, and the extruded an melted resin was cooled and solidified to a film [thickness 90 m, width 1700 mm, density 1.05 g/cm.sup.3] on the surface of a casting roll of a cooling part that was maintained at 25 C. using an air knife.

(30) The speed of the casting roll of a cooling part was 9.6 m/min, and the manufactured base film was oriented in the machine direction (MD) at a melt draft ratio in the extrusion die of 11.7.

(2) Drawing in the Machine Direction (MD) in the Manufacturing Step of a Base Film

(31) To further orient the obtained base film in the machine direction (MD), the speed of the roll at the back end of the casting roll of a cooling part was increased to 10.6 m/min, thereby manufacturing a base film having a final thickness of 85 m and a width of 1632 mm at a draw ratio of 1.1 after the extrusion die.

(3) Coating of Adhesive

(32) Resorcinol and formaldehyde were mixed at a mole ratio of 1:2, and then condensed to obtain a condensate of resorcinol and formaldehyde. 12 wt % of the condensate of resorcinol and formaldehyde and 88 wt % of styrene/butadiene-1,3/vinylpyridine were mixed to obtain a resorcinol-formalin-latex (RFL)-based adhesive at a concentration of 20%.

(33) The resorcinol-formalin-latex (RFL)-based adhesive was coated on the base film to a thickness of 1 m using a gravure coater, and dried at 150 C. for 1 minute and reacted to form an adhesive layer. At this time, drawing in the machine direction (DM) of the base film by a peripheral speed difference between coating rolls was not undertaken.

(34) A melt draft ratio in the extrusion die of 11.7 and a draw ratio after the extrusion die of 1.1 were applied to the obtained film for a tire inner liner, so that total draft in the machine direction of the film became 12.9.

Example 8: Manufacturing of a Film for a Tire Inner Liner

(35) (1) Manufacturing of a Base Film

(36) A base film was manufactured by the same method as Example 7, except for using the following 1) and 2).

(37) 1) The discharge amount of raw material from the die was set to 1770 g/min, and the extruded melted resin was cooled and solidified to a film [thickness 98 m, width 1720 mm] on the surface of a casting roll of a cooling part that was maintained at 25 C. using an air knife.

(38) 2) The speed of the casting roll of a cooling part was 10 m/min, and the manufactured base film was oriented in the machine direction (MD) at a melt draft ratio in the extrusion die of 10.7.

(39) (2) Drawing in the Machine Direction (MD) in the Manufacturing Step of a Base Film

(40) To further orient the obtained base film in the machine direction (MD), the speed of the roll at the back end of the casting roll of a cooling part was increased to 14 m/min, thereby manufacturing a base film having a final thickness of 77 m and a width of 1565 mm at a draw ratio after the extrusion die of 1.4.

(41) (3) Coating of Adhesive

(42) A resorcinol-formalin-latex (RFL)-based adhesive was coated on the obtained base film to a thickness of 1 m to form an adhesive layer by the same method as Example 7.

(43) Total draft of the finally manufactured inner liner film in the machine direction was 15.0.

Example 9: Manufacturing of a Film for a Tire Inner Liner

(44) (1) Manufacturing of a Base Film

(45) An oriented base film was manufactured at a melt draft ratio in an extrusion die of 11.7 by the same method as Example 7, except that additional drawing in the machine direction was not applied in the manufacturing step of the base film.

(46) (2) Coating of Adhesive

(47) Resorcinol and formaldehyde were mixed at a mole ratio of 1:2, and then condensed to obtain a condensate of resorcinol and formaldehyde. 12 wt % of the condensate of resorcinol and formaldehyde and 88 wt % of styrene/butadiene-1,3/vinylpyridine were mixed to obtain a resorcinol-formalin-latex (RFL)-based adhesive at a concentration of 20%.

(48) The resorcinol-formalin-latex (RFL)-based adhesive was coated on the base film to a thickness of 1 m using a gravure coater, and dried at 150 C. for 1 minute and reacted to form an adhesive layer.

(49) In the coating step of the resorcinol-formalin-latex (RFL)-based adhesive, a nipping roll of which speed was controlled identically to the unwinder at the front end of a gravure coater was installed, wherein the speed of the unwinder was set to 20 m/min, and the speed of the winder that wound the base film on which the adhesive layer was formed was set to 26 m/min, so that draft became 1.3, thus orienting the base film on which the adhesive was coated in the machine direction (MD).

(50) The total draft of the finally manufactured inner liner film [thickness 77 m, width 1530 mm] in the machine direction was 15.2.

Example 10: Manufacturing of a Film for a Tire Inner Liner

(51) (1) Manufacturing of a Base Film

(52) A base film that was oriented in the machine direction (MD) was manufactured at a melt draft ratio in an extrusion die of 11.7 by the same method as Example 7.

(53) (2) Drawing in the Machine Direction (MD) in the Manufacturing Step of a Base Film

(54) To further orient the obtained base film in the machine direction (MD), the speed of the roll at the back end of the casting roll of a cooling part was increased to 11.5 m/min, and a draw ratio in the manufacturing step of the base film was set to 1.2.

(55) (3) Coating of Adhesive

(56) Resorcinol and formaldehyde were mixed at a mole ratio of 1:2, and then condensed to obtain a condensate of resorcinol and formaldehyde. 12 wt % of the condensate of resorcinol and formaldehyde and 88 wt % of styrene/butadiene-1,3/vinylpyridine were mixed to obtain a resorcinol-formalin-latex (RFL)-based adhesive at a concentration of 20%.

(57) The resorcinol-formalin-latex (RFL)-based adhesive was coated on the base film to a thickness of 1 m using a gravure coater, and dried at 150 C. for 1 minute and reacted to form an adhesive layer.

(58) In the coating step of the resorcinol-formalin-latex (RFL)-based adhesive, a nipping roll of which speed was controlled identically to the unwinder at the front end of a gravure coater was installed, wherein the speed of the unwinder was set to 20 m/min, and the speed of the winder that wound the base film on which the adhesive layer was formed was set to 24 m/min so that the draft became 1.2, thus orienting the base film on which the adhesive was coated in the machine direction (MD). [Draw ratio after the extrusion die=1.2*1.2]

(59) The total draft of the finally manufactured inner liner film [thickness 71 m, width 1510 mm] in the machine direction was 16.9.

Example 11: Manufacturing of a Film for a Tire Inner Liner

(60) A film for a tire inner liner was manufactured by the same method as Example 7, except that a compounded substance including 50 wt % of a polyamide-based polymer and 50 wt % of a polyether-based polymer was used instead of the copolymer having an absolute weight average molecular weight of 145,000. The density of the base film was 1.05 g/cm.sup.3.

Example 12: Manufacturing of a Pneumatic Tire

(61) (1) The film for a tire inner liner obtained in Examples 1 to 6 was mounted on a tire forming drum in the horizontal direction to the width direction of the tire forming drum, such that the transverse direction (TD) of the base film became the radial direction (a direction parallel to the axial direction of the tire forming drum) of a tire.

(62) (2) The film for a tire inner liner obtained in Examples 7 to 11 was mounted on a tire forming drum in the horizontal direction to the width direction of the tire forming drum, such that the machine direction (MD) of the base film became the radial direction (a direction parallel to the axial direction of the tire forming drum) of a tire.

(63) A body ply layer was laminated on the film for a tire inner liner, a bead wire was attached to the end of the body ply layer in the width direction of the forming drum, a belt part was formed on the body ply layer, a cap ply part was formed on the belt part, and a rubber part was formed on the belt part to manufacture a green tire.

(64) The manufactured green tire was put in a mold, and a tire with a standard of 205R/75R15 was manufactured through vulcanization at 160 for 30 minutes. At this time, 1300De/2ply HMLS tire cord was used as the cord included in the body ply, steel cord was used as the belt, and N66 840De/2ply was used as the cap ply.

Comparative Example

Comparative Example 1

(65) A film for a tire inner liner was manufactured by the same method as Example 1, except that the drawing process of the base film in the transverse direction, after coating the adhesive, was omitted.

Comparative Example 2

(66) A film for a tire inner liner was manufactured by the same method as Example 1, except that the base film was drawn 60% in the transverse direction in the second section of the hot air oven.

Comparative Example 3

(67) A film for a tire inner liner was manufactured by the same method as Example 1, except that the base film was drawn 3% in the transverse direction in the second section of the hot air oven.

Comparative Example 4: Manufacturing of a Film for a Tire Inner Liner

(68) A film for a tire inner liner was manufactured by the same method as Example 7, except that the drawing process in the machine direction in the manufacturing process of the base film was omitted.

Comparative Example 5: Manufacturing of a Film for a Tire Inner Liner

(69) (1) Manufacturing of a Base Film

(70) A base film [thickness 121 m, width 1750 mm] was manufactured by the same method as Example 7, except that the die gap of the t-type die was set to 0.5 mm, and the speed of the casting roll of a cooling part was set to 7 m/min. The melt draft ratio in the extrusion die was 4.3.

(71) (2) Drawing in the Machine Direction (MD) in the Manufacturing Step of a Base Film

(72) To further orient the obtained base film in the machine direction (MD), the speed of the roll at the back end of the casting roll of a cooling part was increased to 7.7 m/min, thereby manufacturing a base film at a draw ratio of 1.1 after the extrusion die.

(73) (3) Coating of Adhesive

(74) A resorcinol-formalin-latex (RFL)-based adhesive was coated on the manufactured base film to a thickness of 1 m using a gravure coater by the same method as Example 7.

(75) The total draft of the finally manufactured inner liner film [thickness 114 m, width 1680 mm] in the machine direction was 4.7.

Comparative Example 6: Manufacturing of a Film for a Tire Inner Liner

(76) (1) Manufacturing of a Base Film

(77) A base film [thickness 89 m, width 1650 mm] was manufactured by the same method as Example 1, except that the die gap of a t-type die was set to 1.3 mm, and the speed of the casting roll of a cooling part was set to 10 m/min. The melt draft ratio in the extrusion die was 15.9.

(78) (2) Drawing in the Machine Direction (MD) in the Manufacturing Step of a Base Film

(79) To further orient the obtained base film in the machine direction (MD), the speed of the roll at the back end of the casting roll of a cooling part was increased to 14 m/min, thereby manufacturing a base film at a draw ratio of 1.4 after the extrusion die.

(80) (3) Coating of Adhesive

(81) A resorcinol-formalin-latex (RFL)-based adhesive was coated on the manufactured base film to a thickness of 1 m using a gravure coater by the same method as Example 7.

(82) The total draft of the finally manufactured inner liner film [thickness 71 m, width 1485 mm] in the machine direction was 22.2.

Comparative Example 7: Manufacturing of a Pneumatic Tire

(83) (1) A pneumatic tire was manufactured by the same method as Example 12, except that the film for a tire inner liner obtained in Comparative Examples 1 to 3 was mounted on a tire forming drum in the horizontal direction to the width direction of the tire forming drum so that the transverse direction (TD) of the base film became the radial direction (a direction parallel to the axial direction of the tire forming drum) of a tire.

(84) (2) A pneumatic tire was manufactured by the same method as Example 12, except that the film for a tire inner liner obtained in Comparative Examples 4 to 6 was mounted on a tire forming drum in the horizontal direction to the width direction of the tire forming drum so that the transverse direction (TD) of the base film became the radial direction (a direction parallel to the axial direction of the tire forming drum) of a tire.

Experimental Example

1. Measurement of Physical Properties of a Film for a Tire Inner Liner

(85) (1) Measurement of the Strength Ratio of the Machine Direction (MD) and the Transverse Direction (TD) of a Film for a Tire Inner Liner

(86) The films for a tire inner liner obtained in the examples and comparative examples were allowed to stand at a temperature of 23 C. under relative humidity of 50% for 24 hours, and then manufactured into a specimen having a length of 30 mm and a width of 30 mm.

(87) The strengths of the machine direction (MD) and the transverse direction (TD) of the manufactured specimens were measured 10 times at a tensile speed of 300 mm/min in a tensile test machine (Instron), and among the measured values, the average value of 8 values excluding the maximum value and the minimum value was calculated.

(88) (2) Oxygen Permeability Test

(89) The oxygen permeability of each film for a tire inner liner obtained in the examples and comparative examples was measured at 25 C. under 60 RH % using an Oxygen Permeation Analyzer (Model 8000, Illinois Instruments product), according to ASTM D 3895.

2. Measurement of Physical Properties of a Tire

(90) (1) Measurement of Durability

(91) The durabilities of the tires obtained in Example 12 and Comparative Example 7 were evaluated while increasing a load using an FMVSS139 tire durability measurement method. The durability measurement was conducted by two methods of an endurance test wherein load was increased by step load, and a high speed test wherein speed was increased.

(92) (1) While the measurement result of the tire using the inner liner film of Comparative Example 1 was considered as 100, the measurement results of the tires using the inner liner films of Examples 1 to 6 and Comparative Examples 2 to 3 were compared and evaluated.

(93) (2) While the measurement result of the tire using the inner liner film of Comparative Example 4 was considered as 100, the measurement results of the tires using the inner liner films of Examples 7 to 11 and Comparative Examples 5 to 6 were compared and evaluated.

(94) (2) Measurement of Internal Pressure Retention

(95) For the tires manufactured using the tire inner liner films of the examples and comparative examples, 90 days internal pressure retention was measured at a temperature of 21 C. under pressure of 101.3 kPa according to ASTM F1112-06. It is recognized that if the IPR value is low when internal pressure retention is high.

(96) (3) Tire Preparation Processibility

(97) It was confirmed whether or not a defect, a tear, a crack, and the like is generated in the finally manufactured tires of Example 12 and Comparative Example 7, to evaluate tire preparation processibility.

(98) In Example 12 and Comparative Example 7, 100 tires were respectively manufactured using the inner liner films of the examples and comparative examples, the inside of each manufactured tire was observed with the naked eye, and the number of normal products without crystals and the like was confirmed to calculate a yield of normal products.

(99) The results of the Experimental Example are shown in the following Table 1 and Table 2.

(100) TABLE-US-00001 TABLE 1 The results of experiments of Examples 1 to 6 and Comparative Examples 1 to 3 Durability Durability Strength Oxygen measurement measurement Internal pressure Tire/ ratio permeability Endurance High Speed Test retention (IPR) processibility (TD/MD) cc/(m.sup.2 .Math. 24 hr .Math. atm) Test (%) (%) [%/3 months] (%) Example 1 1.54 76 183 178 2.1 100 Example 2 1.86 63 203 206 1.3 100 Example 3 1.15 93 156 148 2.6 99.7 Example 4 1.31 82 176 178 1.8 100 Example 5 1.72 70 192 193 1.2 100 Example 6 1.55 78 180 170 2.3 100 Comparative 0.83 103 100 100 15 15.2 Example 1 Comparative 2.31 58 38 50 58 25.1 Example 2 Comparative 1.02 98 103 102 5.5 33.2 Example 3

(101) As shown in Table 1, it is confirmed that the tire inner liner films of Examples 1 to 6 have a ratio of the strength of the transverse direction (TD) to the strength of the machine direction (MD) of 1.31 to 1.86, the tire inner liner films have optimum oxygen permeability and internal pressure retention and simultaneously may secure excellent durability when practically applied to a tire, and have superior tire processibility compared to the inner liner films of the comparative examples.

(102) To the contrary, when the inner liner films of Comparative Example 1 and Comparative Example 3 are used, it is confirmed that an orientation difference between the circumferential direction and the radial direction of a tire is significantly generated in the manufacturing process of a tire, thus inducing a thickness difference and partial non-uniformity of physical properties of the inner liner films, and thus durability, internal pressure retention, and processibility of a tire are lowered.

(103) Further, when the inner liner film of Comparative Example 2 is used, it is confirmed that when drawn in the transverse direction of the base film, the adhesive layer on the base film is broken to show lowered adhesion to a carcass layer, and thus durability, internal pressure retention, and tire processibility are significantly lowered.

(104) TABLE-US-00002 TABLE 2 Results of experiments of Examples 7 to 11 and Comparative Examples 4 to 6 Example Example Comparative Comparative Comparative Example 7 Example 8 Example 9 10 11 Example 4 Example 5 Example 6 Strength ratio 1.2 1.4 1.4 1.8 1.2 1.1 1.0 2.2 (MD/TD) Oxygen 78 83 92 100 76 115 110 65 permeability cc/(m.sup.2 .Math. 24 hr .Math. atm) Durability 145 175 165 183 143 100 105 53 measurement Endurance Test (%) Durability 138 183 168 153 139 100 103 55 measurement High Speed Test (%) Internal pressure 1.8 1.5 1.3 1.2 1.9 45 40 50 retention (IPR) [%/3 months] Tire processibility 99.3 100 100 100 99.5 20.2 30.3 5.1 (%)

(105) As shown in Table 2, it is confirmed that the tire inner liner films of Examples 7 to 11 have a ratio of the transverse direction (TD) to the machine direction (DM) of 1.2 to 1.8. Further, the tire inner liner films may have optimum oxygen permeability and internal pressure retention and simultaneously secure excellent durability when practically applied to a tire, and the tire processibility is superior to the inner liner films of the comparative examples.

(106) To the contrary, when the inner liner films of Comparative Examples 4 and 6 are used, it is confirmed that an orientation difference between the circumferential direction and the radial direction of a tire is significantly generated in the tire manufacturing process, which induces a thickness difference and partial non-uniformity of physical properties of the inner liner films, and thus durability, internal pressure retention, and processibility of a tire are lowered.

(107) Specifically, in the case of Comparative Example 4, an orientation difference between the circumferential direction and the radial direction of a tire is significantly generated in the tire manufacturing process, which induces a thickness difference and partial non-uniformity of physical properties of the inner liner films, thus lowering durability, internal pressure retention, and processibility of a tire.

(108) In the case of Comparative Example 5, although an orientation difference between the circumferential direction and the radial direction of a tire is less generated compared to Comparative Example 1, a thickness difference and partial non-uniformity of physical properties of the inner liner film are still generated, thus lowering durability, internal pressure retention, and processibility.

(109) In the case of Comparative Example 6, an orientation difference between the circumferential direction and the radial direction of a tire is significantly generated, and tearing of the inner liner film frequently occurred after manufacturing a tire, thus making it difficult to manufacture a normal product.