Polymer films

Abstract

There is provided a polymer film which includes: a base film layer including a polyamide-based resin having a particular relative viscosity and a copolymer including a polyamide-based segment and a polyether-based segment having a specific content; and an adhesive layer formed on at least one side of the base film layer, wherein a ratio of the melt viscosity of the copolymer to the melt viscosity of the polyamide resin is 0.65 to 1.2 at a shear rate of 1000 s.sup.1 and a temperature of 260 C.

Claims

1. A polymer film which comprises: a base film layer comprising a polyamide-based resin having a relative viscosity (96% sulfuric acid solution) of 3.0 to 3.5, an olefinic polymer compound, and a copolymer comprising a polyamide-based segment and a polyether-based segment; and an adhesive layer formed on at least one side of the base film layer and containing resorcinol-formalin-latex (RFL)-based adhesive, wherein a content of the polyether-based segment of the copolymer is more than 2% by weight and less than 15% by weight with respect to the total weight of the base film layer, and wherein a ratio of a melt viscosity of the copolymer to a melt viscosity of the polyamide resin is 0.60 to 1.2 at a shear rate of 1000 s1 and a temperature of 260 C., and the olefinic polymer compound includes a dicarboxylic acid or its acid anhydride-grafted olefinic polymer or copolymer, wherein the polyamide-based resin, the copolymer, and the olefinic polymer compound, respectively are included in a weight ratio of 2:2:1 to 3.5:6.5:2 in the base film layer.

2. The polymer film of claim 1, wherein the polymer film is used for a tire inner liner.

3. The polymer film of claim 1, wherein the ratio of the melt viscosity of the copolymer to the melt viscosity of the polyamide resin is 1.0 to 2.0 at a shear rate of 100 s.sup.1 and a temperature of 260 C.

4. The polymer film of claim 1, wherein the ratio of the melt viscosity of the copolymer to the melt viscosity of the polyamide resin is 0.60 to 1.1 at a shear rate of 2000 s.sup.1 and a temperature of 260 C.

5. The polymer film of claim 1, wherein the ratio of the melt viscosity of the copolymer to the melt viscosity of the polyamide resin is 0.7 to 1.5 at a shear rate of 500 s.sup.1 and a temperature of 260 C.

6. The polymer film of claim 1, wherein the grafted dicarboxylic acid or its acid anhydride is contained in an amount of 0.1% to 10% by weight.

7. The polymer film of claim 1, wherein the base film layer includes 0.1% by weight to 40% by weight of the olefinic polymer compound.

8. The polymer film of claim 1, wherein the relative viscosity (96% sulfuric acid solution) of the polyamide-based resin is 3.2 to 3.4.

9. The polymer film of claim 1, wherein the absolute weight average molecular weight of the copolymer containing polyamide-based segments and polyether-based segments is 50,000 to 300,000.

10. The polymer film of claim 1, wherein the polyamide-based segment includes a repeating unit of the following Chemical Formula 1 or Chemical Formula 2: ##STR00003## wherein, in Chemical Formula 1, R.sub.1 is a linear or branched alkylene group having 1 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a linear or branched arylalkylene group having 7 to 20 carbon atoms; and ##STR00004## wherein, in Chemical Formula 2, R.sub.2 is a linear or branched alkylene group having 1 to 20 carbon atoms, and R.sub.3 is a linear or branched alkylene group having 1 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms, or a linear or branched arylalkylene group having 7 to 20 carbon atoms.

11. The polymer film of claim 1, wherein the polyether-based segment of the copolymer includes a repeating unit of the following Chemical Formula 3:
R.sub.6R.sub.5O.sub.nR.sub.7[Chemical Formula 3] wherein, in Chemical Formula 3, R.sub.5 is a linear or branched alkylene group having 1 to 10 carbon atoms, n is an integer of 1 to 100, and R.sub.6 and R.sub.7 may be identical or different, and are independently a direct bond, O, NH, COO, or CONH.

12. The polymer film of claim 1, wherein the copolymer includes the polyamide-based segment and the polyether-based segment in a weight ratio of 1:9 to 9:1.

13. The polymer film of claim 1, wherein the base film layer has a thickness of 30 m to 300 m, and the adhesive layer has a thickness of 0.1 m to 20 m.

14. The polymer film of claim 1, wherein the base film layer is an undrawn film.

15. The polymer film of claim 1, wherein the resorcinol-formalin-latex (RFL)-based adhesive includes 2% to 30% by weight of a condensate of resorcinol and formaldehyde and 68% to 98% by weight of a latex.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

DETAILED DESCRIPTION OF THE EMBODIMENTS

(2) Specific embodiments of the invention will be explained in detail in the following examples. However, these examples are only to illustrate specific embodiments of the invention, and the scope of the invention is not limited thereto.

Example: Manufacture of a Polymer Film

Example 1

(3) (1) Manufacturing of a Base Film

(4) A polyamide-based resin (nylon 6) having a relative viscosity (96% sulfuric add solution) of 3.3, a copolymer resin having an absolute weight average molecular weight of 145,000 (synthesized using 45% by weight of polyethylene glycol having a terminal amine group and 55% by weight of nylon 6 resin), and a maleic anhydride-grafted (0.7 wt %) ethylene-propylene copolymer (density: 0.870 g/cm.sup.3) were mixed with a weight ratio of 4:4:2.

(5) At this time, the raw material feeder was adjusted to a temperature of 50 C. to 100 C. and then the above mixture was supplied to an extrusion die, while preventing the mixture from being fused in an extruder screw and thus causing a feeding failure.

(6) Then, the supplied mixture was extruded through a T-type die (die gap1.0 mm) at a temperature of 260 C. while maintaining uniform flow of melted resin. The extruded melted resin was cooled and solidified into a film with a uniform thickness using an air knife on the surface of a cooling roll that was controlled to 25 C.

(7) Subsequently, a undrawn base film having a thickness of 100 m was obtained without going through the drawing and heat treatment section at a speed of 15 m/min.

(8) (2) Coating of Adhesive

(9) Resorcinol and formaldehyde were mixed at a mole ratio of 1:2, and then subjected to a condensation reaction to obtain a condensate of resorcinol and formaldehyde.

(10) 12% by weight of the condensate of resorcinol and formaldehyde and 88% by weight of styrene/butadiene-1,3/vinylpyridine latex were mixed to obtain a resorcinol-formalin-latex (RFL)-based adhesive with concentration of 20%.

(11) 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 and reacted at 150 C. for 1 min to form an adhesive layer.

Example 2

(12) (1) Manufacturing of a Base Film

(13) The base film was manufactured in the same manner as in Example 1, except that a polyamide-based resin (nylon 6) having a relative viscosity (96% sulfuric add solution) of 3.3, a copolymer resin having an absolute weight average molecular weight of 145,000 (synthesized using 45% by weight of polyethylene glycol having a terminal amine group and 55% by weight of nylon 6 resin), and a maleic anhydride-grafted (0.7 wt %) ethylene-propylene copolymer (density: 0.870 g/cm.sup.3) were mixed with a weight ratio of 3.5:6.5:2.

(14) (2) Coating of Adhesive

(15) The adhesive layer was formed on the manufactured base film by the same method as in Example 1.

Comparative Example: Manufacture of a Polymer Film

Comparative Example 1

(16) (1) Manufacturing of a Base Film

(17) The base film was manufactured in the same manner as in Example 1, except that nylon 6 resin having a relative viscosity (96% sulfuric acid solution) of 2.54 was used.

(18) (2) Coating of Adhesive

(19) The adhesive layer was formed on the above manufactured base film by the same method as in Example 1.

Comparative Example 2

(20) (1) Manufacturing of a Base Film

(21) The base film was manufactured by the same method as in Example 2, except that nylon 6 resin having a relative viscosity (96% sulfuric acid solution) of 2.54 was used.

(22) (2) Coating of Adhesive

(23) The adhesive layer was formed on the above manufactured base film by the same method as in Example 1.

Comparative Example 3

(24) (1) Manufacturing of a Base Film

(25) The base film was manufactured by the same method as in Example 1, except that 50% by weight of a polyamide-based resin (nylon 6) having a relative viscosity (96% sulfuric acid solution) of 3.3, and 50% by weight of a copolymer resin having an absolute weight average molecular weight of 150,000 (synthesized using 80% by weight of polyethylene glycol having a terminal amine group and 20% by weight of nylon 6 resin) were mixed.

(26) (2) Coating of Adhesive

(27) The adhesive layer was formed on the above manufactured base film by the same method as in Example 1.

Comparative Example 4

(28) (1) Manufacturing of a Base Film

(29) The base film was manufactured by the same method as in Example 1, except that 50% by weight of a polyamide-based resin (nylon 6) having a relative viscosity (96% sulfuric acid solution) of 2.54, and 50% by weight of a copolymer resin having an absolute weight average molecular weight of 150,000 (synthesized using 80% by weight of polyethylene glycol having a terminal amine group and 20% by weight of nylon 6 resin) were mixed.

(30) (2) Coating of Adhesive

(31) The adhesive layer was formed on the above manufactured base film by the same method as in Example 1.

Experimental Example: Measurement of Physical Properties of a Polymer Film

Experimental Example 1: Measurement of Melt Viscosity

(32) The melt viscosities of the nylon 6 and the copolymer resin used in the examples and comparative examples, respectively, were measured at orifice diameter 1 mm*length 20 mm at a temperature of 260 C. and a shear rate shown in Table 1 below, using a Rheo-Tester 2000 (GOTTFERT GMBH).

(33) The ratio of the melt viscosity of the copolymer to the melt viscosity of the polyamide-based resin was obtained from the above measured melt viscosity.

(34) The results are shown in Table 1 below.

(35) TABLE-US-00001 TABLE 1 Results of experiment 1 Ratio of the melt viscosity of the copolymer to the melt viscosity of the polyamide-based resin (260 C.) Shear rate 100 s.sup.1 500 s.sup.1 1000 s.sup.1 2000 s.sup.1 Example 1 1.029 0.746 0.685 0.672 Example 2 1.040 1.762 0.718 0.702 Comparative 3.285 1.710 1.373 1.196 Example 1 Comparative 4.910 2.374 1.863 1.539 Example 2 Comparative 0.923 0.686 0.639 0.628 Example 3 Comparative 2.692 1.574 1.294 1.125 Example 4

Experimental Example 2: Oxygen Permeability Test

(36) The oxygen permeability of each film for a tire inner liner obtained in the examples and comparative examples was measured.

(37) The specific measurement method thereof is as follows.

(38) (1) Oxygen permeability: measured at 25 C. under a 60 RH % atmosphere using an Oxygen Permeation Analyzer (Model 8000, Illinois Instruments product) according to ASTM D 3895.

Experimental Example 3: Measurement of Internal Pressure Retention

(39) The tire was manufactured using the tire inner liner films of the examples and comparative examples according to the standard 205R/65R16.

(40) Then, 90-day internal pressure retention according to the following Equation 3 was measured at a temperature of 21 C. under a pressure of 101.3 kPa in accordance with ASTM F1112-06.
Internal Pressure Retention (%)={1(Tire inflation pressure upon initial testingTire inflation pressure after having been left for 90 days)/(Tire inflation pressure upon initial testing)}100[Equation 3]

(41) The results of Experimental Example 2 and Experimental Example 3 are shown in Table 2 below.

(42) TABLE-US-00002 TABLE 2 Results of Experimental Examples 2 and 3 Oxygen permeability Internal pressure retention Unit cc/(m.sup.2 .Math. 24 h .Math. atm) % Example 1 83 1.5 Example 2 98 1.7 Comparative 70 1.4 Example 1 Comparative 109 1.9 Example 2 Comparative 40 1.2 Example 3 Comparative 50 1.1 Example 4

Experimental Example 4: Determination of the Ease of Molding

(43) The tire was manufactured using the tire liner film of the examples and comparative examples according to the standard 205R/65R16.

(44) In the method for manufacturing a tire, a green tire was manufactured and then the manufacturing ease and appearance were evaluated. Then, after vulcanization, the final appearance of the tire was observed.

(45) In this case, when there was no distortion in a green tire or a the after vulcanization and a standard deviation of diameter was within 5%, it was evaluated as good.

(46) Also, when distortion was generated in a green tire or a tire after vulcanization and thus the tire was not properly made or the tire inner liner was melted or torn and broken or when a standard deviation of diameter was greater than 5%, it was evaluated as poor form.

Experimental Example 5: Measurement of Durability

(47) The durability of the tires was evaluated while increasing a load using an FMVSS139 tire durability measurement method.

(48) The durability measurement was conducted by two methods of an endurance test wherein a load was increased by a step load, and a high speed test wherein speed was increased, to thereby verify the presence of cracks in the inside of the tire. When there were no cracks, it was indicated as good, and when cracks incurred, it was indicated as crack.

(49) The results of the Experimental Examples 4 and 5 are shown in Table 3 below.

(50) TABLE-US-00003 TABLE 3 Results of Experimental Examples 4 and 5 Manufacturing state Durability Durability of a green tire/state measurement measurement of a final tire (Endurance test) (High speed test) Example 1 Good/good Good Good Example 2 Good/good Good Good Comparative Good/bad form Crack rack Example 1 Comparative Good/bad form Crack rack Example 2 Comparative Bad form/bad form Example 3 Comparative Bad form/bad form Example 4

(51) As shown in Table 1 above, the tire inner liner films of Examples 1 and 2 obtained using a polyamide-based resin having a relative viscosity (96% sulfuric acid solution) of 3.3 and a particular copolymer resin (the polyether-based segments are contained in an amount of 22.5% by weight and 39% by weight, respectively, based on the total weight of the based film) showed that a ratio of the melt viscosity (at 260 C.) of the copolymer to the melt viscosity of the polyamide-based resin ranges from 1.0 to 2.0 at a shear rate of 100 s.sup.1, from 0.7 to 1.5 at a shear rate of 500 s.sup.1, from 0.65 to 1.2 at a shear rate of 1000 s.sup.1, and from 0.65 to 1.1 at a shear rate of 2000 s.sup.1.

(52) In addition, in Examples 1 and 2, the polyamide-based resin and the copolymer were uniformly kneaded with each other and melted and thus a base film layer having uniform physical properties in the entire area of the film could be formed. Further, as confirmed from the results of Experimental Example 2 and 3 in Table 2, the polymer films of the examples using the base film layer not only have excellent moldability but also high gas barrier property and internal pressure retention performance.

(53) In contrast, in Comparative Examples 1, 2, and 4, it was confirmed that that a ratio of the melt viscosity of the copolymer to the melt viscosity of the polyamide-based resin is greater than 2.5 at a shear rate of 100 s.sup.1 and a temperature of 260 C., greater than 1.5 at a shear rate of 500 s.sup.1 and a temperature of 260 C., greater than 1.2 at a shear rate of 1000 s.sup. and a temperature of 260 C., and greater than 1.1 at a shear rate of 2000 s.sup.1 and a temperature of 260 C.

(54) In other words, if the polyamide-based resin and the copolymer used in Comparative Examples 1, 2, and 4 were kneaded to form a base film layer, the mixing was not easy due to a great difference in the melt density, and a phase separation phenomenon between the two components could occur.

(55) As confirmed from the results of Experimental Examples 2 and 3, the polymer film obtained in Comparative Examples 1, 2, and 4 had problems in that moldability was significantly diminished even when a tire was actually made and tested, and that cracks were generated when a durability test was conducted.

(56) Further, in the case of Comparative Example 3, it was confirmed that a ratio of the melt viscosity of the copolymer to the melt viscosity of the polyamide-based resin was less than 1.0 at a shear rate of 100 s.sup.1 and a temperature of 260 C., less than 0.7 at a shear rate of 500 s.sup.1 and a temperature of 260 C., and less than 0.65 at a shear rate of 1000 s.sup.1 and a temperature of 260 C.

(57) In other words, if the polyamide-based resin and the copolymer used in Comparative Example 3 were kneaded to form a base film layer, the mixing is not easy due to a great difference in the melt density, and the phase separation phenomenon between the two components could occur.

(58) Further, in the case of Comparative Example 3, like other comparative examples, it was confirmed from the results of Experimental Examples 2 and 3 that moldability was significantly diminished even when a tire was actually molded and also that the desired gas barrier property and internal pressure retention performance were not obtained.