HYBRID TIRE CORD AND METHOD FOR MANUFACTURING THE SAME

Abstract

Disclosed are a high-performance hybrid tire cord capable of realizing high performance and lightweight of a tire, and a method for manufacturing same. The hybrid tire cord of the present invention comprises a PET primarily-twisted yarn, an aramid primarily-twisted yarn, and an adhesive coated on the PET primarily-twisted yarn and the aramid primarily-twisted yarn. In the hybrid tire cord having a predetermined length, the length of the aramid primarily-twisted yarn is 1 to 1.1 times the length of the PET primarily-twisted yarn, after the secondary twist is untwisted.

Claims

1. A hybrid tire cord comprising: PET primarily twisted yarn; aramid primarily twisted yarn; and an adhesive coated on the PET primarily twisted yarn and on the aramid primarily twisted yarn, wherein the PET primarily twisted yarn and the aramid primarily twisted yarn are secondarily twisted with each other, and a length of the aramid primarily twisted yarn is 1 to 1.1 times a length of the PET primarily twisted yarn after a predetermined length of the hybrid tire cord is untwisted.

2. The hybrid tire cord according to claim 1, wherein the PET primarily twisted yarn is made of PET filaments having 400 to 3000 denier, and the aramid primarily twisted yarn is made of aramid filaments having 400 to 3000 denier.

3. The hybrid tire cord according to claim 2, wherein the PET primarily twisted yarn has 1300 to 3000 denier, and the aramid primarily twisted yarn has 1500 to 3000 denier.

4. The hybrid tire cord according to claim 1, wherein the PET primarily twisted yarn has a first twisting direction, the aramid primarily twisted yarn has a second twisting direction, the PET primarily twisted yarn and the aramid primarily twisted yarn are secondarily twisted with each other in a third twisting direction, the second twisting direction is a same as the first twisting direction, and the third twisting direction is opposite the first twisting direction.

5. The hybrid tire cord according to claim 1, wherein each of the PET primarily twisted yarn and the aramid primarily twisted yarn has a first twist number of 200 to 500 TPM.

6. The hybrid tire cord according to claim 5, wherein the PET primarily twisted yarn and the aramid primarily twisted yarn are secondarily twisted with each other so as to have a second twist number, and the second twist number is a same as the first twist number.

7. The hybrid tire cord according to claim 1, wherein a weight ratio of the aramid primarily twisted yarn to the PET primarily twisted yarn is 20:80 to 80:20.

8. The hybrid tire cord according to claim 7, wherein the weight ratio of the aramid primarily twisted yarn to the PET primarily twisted yarn is 1:3 to 3:1.

9. The hybrid tire cord according to claim 1, wherein the hybrid tire cord has a strength at break of 8.0 to 15.0 g/d, measured according to ASTM D885, and an elongation at break of 5 to 15%, measured according to ASTM D885.

10. The hybrid tire cord according to claim 1, wherein a strength retention rate of the hybrid tire cord after disk fatigue testing, performed according to a JIS-L 1017 method of Japanese Standards Association (JSA), is 80% or higher.

11. The hybrid tire cord according to claim 1, wherein the hybrid tire cord has 3% LASE of 6 kgf or more, 5% LASE of 10 kgf or more, and 7% LASE of 17 kgf or more, measured according to ASTM D885.

12. The hybrid tire cord according to claim 11, wherein the hybrid tire cord has 3% LASE of 8 kgf or more, 5% LASE of 15 kgf or more, and 7% LASE of 25 kgf or more, measured according to ASTM D885.

13. The hybrid tire cord according to claim 1, wherein a dry heat shrinkage of the hybrid tire cord, measured under conditions of a temperature of 180r, a time of 2 minutes, and a primary load of 0.01 g/d, is 0.3 to 2.5%.

14. A method of manufacturing a hybrid tire cord, the method comprising: primarily twisting aramid filaments in a first direction to form aramid primarily twisted yarn; primarily twisting PET filaments in a second direction to form PET primarily twisted yarn; secondarily twisting the aramid primarily twisted yarn and the PET primarily twisted yarn with each other in a third direction to form cabled yarn; dipping the cabled yarn in an adhesive solution; drying the cabled yarn penetrated with the adhesive solution as a result of being dipped; and heat treating the dried cabled yarn, wherein the second direction is a same as the first direction, the third direction is opposite the first direction, and a tension applied to the PET filament in forming the PET primarily twisted yarn is lower than a tension applied to the aramid filament in forming the aramid primarily twisted yarn.

15. The method according to claim 14, wherein a length of the PET primarily twisted yarn is 1.005 to 1.050 times a length of the aramid primarily twisted yarn after a predetermined length of the cabled yarn, formed at the step of forming the cabled yarn, is untwisted.

16. The method according to claim 14, wherein a tension applied to the PET filament in forming the PET primarily twisted yarn is 50% to 95% of a tension applied to the aramid filament in forming the aramid primarily twisted yarn.

17. The method according to claim 14, wherein forming the aramid primarily twisted yarn, forming the PET primarily twisted yarn and forming the cabled yarn are performed in a single twisting machine.

18. The method according to claim 14, wherein forming the aramid primarily twisted yarn and the PET primarily twisted yarn, and forming the cabled yarn are successively performed.

19. The method according to claim 14, wherein the adhesive solution comprises at least one of a resorcinol-formaldehyde-latex (RFL) adhesive and an epoxy-based adhesive.

20. The method according to claim 14, wherein the drying is performed at 70 to 200r for 30 to 120 seconds, and the heat treating is performed at 200 to 250 C. for 30 to 120 seconds.

21. 1 The method according to claim 14, wherein the dipping, the drying, and the heat treating step are successively performed, and a tension applied to the cabled yarn at the dipping, the drying, and the heat treating is 0.4 kg/cord or higher.

22. The method according to claim 14, wherein, after the heat treating, a length of the aramid primarily twisted yarn, measured after the hybrid tire cord is untwisted, is 1 to 1.1 times a length of the PET primarily twisted yarn.

23. A hybrid tire cord for carcasses, the hybrid tire cord comprising: PET primarily twisted yarn; aramid primarily twisted yarn; and an adhesive coated on the PET primarily twisted yarn and on the aramid primarily twisted yarn, wherein the PET primarily twisted yarn and the aramid primarily twisted yarn are secondarily twisted with each other, and a length of the aramid primarily twisted yarn is 1 to 1.1 times a length of the PET primarily twisted yarn after a predetermined length of the hybrid tire cord is untwisted.

Description

EXAMPLE 1

[0111] PET filaments having 1000 denier and aramid filaments having 1000 denier were introduced into a cable cord twisting machine (Cable Corder made by Allma Company), and Z-directional primary twisting and S-directional secondary twisting were simultaneously and successively performed to manufacture 2-ply cabled yarn (i.e. raw cord). At this time, the cable cord twisting machine was set so as to perform primary twisting and secondary twisting with a twist number of 460 TPM, and the tension applied to each of the PET filaments and the aramid filaments was adjusted such that the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (length of the PET primarily twisted yarn/the length of the aramid primarily twisted yarn) (L.sub.P/L.sub.A) was 1.005. In order to acquire the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn, a load of 0.05 g/d was applied to a sample of the cabled yarn (raw cord) having a length of 1 m in order to release and untwist the secondary twisting such that the aramid primarily twisted yarn and the PET primarily twisted yarn were separated from each other, and the length of the aramid primarily twisted yarn and the length of the PET primarily twisted yarn were measured in the state in which a load of 0.05 g/d was applied to each of the aramid primarily twisted yarn and the PET primarily twisted yarn.

[0112] Subsequently, the cabled yarn (raw cord) was dipped in a resorcinol-formaldehyde-latex (RFL) adhesive solution including 2.0 wt % of resorcinol, 3.2 wt % of formalin (37%), 1.1 wt % of sodium hydroxide (10%), 43.9 wt % of styrene/butadiene/vinylpyridine (15/70/15) rubber (41%), and water. The cabled yarn (raw cord) penetrated with the RFL solution as the result of being dipped was dried at 150 C. for 100 seconds and was then heat treated at 240 C. for 100 seconds to manufacture a hybrid tire cord, i.e. a dip cord. The tension applied to the cabled yarn during the dipping, drying, and heat treating processes was 0.5 kg/cord.

EXAMPLE 2

[0113] A hybrid tire cord (dip cord) was manufactured using the same method as in Example 1, except that the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (L.sub.P/L.sub.A) was 1.010.

EXAMPLE 3

[0114] A hybrid tire cord (dip cord) was manufactured using the same method as in Example 1, except that the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (L.sub.P/L.sub.A) was 1.020.

EXAMPLE 4

[0115] A hybrid tire cord (dip cord) was manufactured using the same method as in Example 1, except that the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (L.sub.P/L.sub.A) was 1.030.

EXAMPLE 5

[0116] A hybrid tire cord (dip cord) was manufactured using the same method as in Example 1, except that the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (L.sub.P/L.sub.A) was 1.050.

EXAMPLE 6

[0117] A PET filament having 1500 denier and an aramid filament having 1500 denier were introduced into a cable cord twisting machine (Cable Corder made by Allma Company), and Z-directional primary twisting and S-directional secondary twisting were simultaneously and successively performed to manufacture 2-ply cabled yarn (i.e. a raw cord). At this time, the cable cord twisting machine was set so as to perform primary twisting and secondary twisting with a twist number of 380 TPM, and the tension applied to each of the PET filaments and the aramid filaments was adjusted such that the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (length of the PET primarily twisted yarn/the length of the aramid primarily twisted yarn) (L.sub.P/L.sub.A) was 1.03. In order to acquire the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn, a load of 0.05 g/d was applied to a sample of the cabled yarn (raw cord) having a length of 1 m in order to release and untwist the secondary twisting such that the aramid primarily twisted yarn and the PET primarily twisted yarn were separated from each other, and the length of the aramid primarily twisted yarn and the length of the PET primarily twisted yarn were measured in the state in which a load of 0.05 g/d was applied to each of the aramid primarily twisted yarn and the PET primarily twisted yarn.

[0118] Subsequently, the cabled yarn (raw cord) was dipped in a resorcinol-formaldehyde-latex (RFL) adhesive solution including 2.0 wt % of resorcinol, 3.2 wt % of formalin (37%), 1.1 wt % of sodium hydroxide (10%), 43.9 wt % of styrene/butadiene/vinylpyridine (15/70/15) rubber (41%), and water. The cabled yarn (raw cord) penetrated with the RFL solution as the result of being dipped was dried at 150 C. for 100 seconds and was then heat treated at 240 C. for 100 seconds to manufacture a hybrid tire cord. The tension applied to the cabled yarn during the dipping, drying, and heat treating processes was 0.5 kg/cord.

EXAMPLE 7

[0119] A hybrid tire cord was manufactured using the same method as in Example 6, except that PET filaments having 2000 denier was used instead of the PET filaments having 1500 denier, aramid filaments having 2000 denier was used instead of the aramid filaments having 1500 denier, and the cable cord twisting machine was set so as to perform primary twisting and secondary twisting with a twist number of 300 TPM.

EXAMPLE 8

[0120] A hybrid tire cord was manufactured using the same method as in Example 6, except that the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (L.sub.P/L.sub.A) was 1.005.

EXAMPLE 9

[0121] A hybrid tire cord was manufactured using the same method as in Example 6, except that the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (L.sub.P/L.sub.A) was 1.05.

Comparative Example 1

[0122] A hybrid tire cord (dip cord) was manufactured using the same method as in Example 1, except that the cable cord twisting machine was set so as to perform primary twisting and secondary twisting with a twist number of 360 TPM, and the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (L.sub.P/L.sub.A) was 0.980.

Comparative Example 2

[0123] A hybrid tire cord (dip cord) was manufactured using the same method as in Example 1, except that the cable cord twisting machine was set so as to perform primary twisting and secondary twisting with a twist number of 400 TPM, and the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (L.sub.P/L.sub.A) was 0.980.

Comparative Example 3

[0124] A hybrid tire cord (dip cord) was manufactured using the same method as in Example 1, except that the cable cord twisting machine was set so as to perform primary twisting and secondary twisting with a twist number of 430 TPM, and the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (L.sub.P/L.sub.A) was 0.980.

Comparative Example 4

[0125] A hybrid tire cord (dip cord) was manufactured using the same method as in Example 1, except that the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (L.sub.P/L.sub.A) was 0.980.

Comparative Example 5

[0126] A hybrid tire cord (dip cord) was manufactured using the same method as in Example 6, except that the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (L.sub.P/L.sub.A) was 1.000.

Comparative Example 6

[0127] A hybrid tire cord (dip cord) was manufactured using the same method as in Example 6, except that the ratio of the length of the PET primarily twisted yarn to the length of the aramid primarily twisted yarn in the cabled yarn (raw cord) (L.sub.P/L.sub.A) was 0.98.

[0128] Examples 1 to 9 and Comparative Examples 1 to 6 are summarized in Table 1 below.

TABLE-US-00001 TABLE 1 Denier of Denier of Number of PET aramid primary/ primarily primarily secondary twisted twisted twists (L.sub.P/L.sub.A) yarn yarn (TPM) (Raw Cord) Example 1 1000 1000 460 1.005 Example 2 1000 1000 460 1.010 Example 3 1000 1000 460 1.020 Example 4 1000 1000 460 1.030 Example 5 1000 1000 460 1.050 Example 6 1500 1500 380 1.030 Example 7 2000 2000 300 1.030 Example 8 1500 1500 380 1.005 Example 9 1500 1500 380 1.050 Comparative 1000 1000 360 0.980 Example 1 Comparative 1000 1000 400 0.980 Example 2 Comparative 1000 1000 430 0.980 Example 3 Comparative 1000 1000 460 0.980 Example 4 Comparative 1500 1500 380 1.000 Example 5 Comparative 1500 1500 380 0.980 Example 6

[0129] For the hybrid tire cords (dip cords) manufactured according to Examples 1 to 9 and Comparative Examples 1 to 6, (i) the ratio of the length of the aramid primarily twisted yarn to the length of the PET primarily twisted yarn (length of the aramid primarily twisted yarn/the length of the PET primarily twisted yarn) (L.sub.A/L.sub.P), (ii) strength, elongation at specific load (at 4.5 kg), and elongation at break, (iii) 3% LASE, 5% LASE, and 7% LASE, (iv) dry heat shrinkage, and (v) the strength retention rate after disk fatigue testing were measured using the following methods, and the results are shown in Table 2.

[0130] (i) The ratio of the length of the aramid primarily twisted yarn to the length of the PET primarily twisted yarn (L.sub.A/L.sub.P)

[0131] A load of 0.05 g/d was applied to samples of the hybrid tire cord having a length of 1 m in order to release and untwist the secondary twisting such that the aramid primarily twisted yarn and the PET primarily twisted yarn were separated from each other, and the length of the aramid primarily twisted yarn and the length of the PET primarily twisted yarn were measured in the state in which a load of 0.05 g/d was applied to each of the aramid primarily twisted yarn and the PET primarily twisted yarn.

[0132] Subsequently, the value of the length of the aramid primarily twisted yarn/the length of the PET primarily twisted yarn) (L.sub.A/L.sub.P) was calculated.

[0133] (ii) Strength (kgf), elongation at specific load (at 4.5 kg) (%), and elongation at break (%)

[0134] 10 samples having a length of 250 mm were tensioned at a cross-head speed of 300 m/min using Instron Tester (Instron Engineering Corp., Canton, Mass) according to ASTM D-885 testing method in order to measure the strength, elongation at specific load (at 4.5 kg), and elongation at break thereof. Subsequently, the average of each of the strength, elongation at specific load (at 4.5 kg), and elongation at break of the 10 samples was calculated in order to determine the strength, elongation at specific load (at 4.5 kg), and elongation at break of the hybrid tire cord (dip cord).

[0135] (iii) 3% LASE, 5% LASE, and 7% LASE

[0136] 10 samples having a length of 250 mm were tensioned at a cross-head speed of 300 m/min using Instron Tester (Instron Engineering Corp., Canton, Mass) according to the ASTM D-885 testing method in order to measure 3% LASE, 5% LASE, and 7% LASE of the hybrid tire cord. Subsequently, the average of each of 3% LASE, 5% LASE, and 7% LASE of the 10 samples was calculated in order to obtain 3% LASE, 5% LASE, and 7% LASE of the hybrid tire cord.

[0137] (iv) Dry heat shrinkage

[0138] Samples were placed under atmospheric conditions of a temperature of 25 C. and a relative humidity of 65% for 24 hours, and then the dry heat shrinkage of the samples was measured using a Testrite instrument under conditions of a temperature of 180 C., a time of 2 minutes, and a primary load of 0.01 g/d (20 g).

[0139] (v) Strength retention rate after disk fatigue testing

[0140] The hybrid tire cord (dip cord), the strength (strength before fatigue) of which was measured, was vulcanized with rubber to manufacture samples, and the samples were repeatedly tensioned and contracted within a range of 8% for 16 hours while the samples were rotated at a speed of 2500 rpm at 80 C. using a disk fatigue tester according to the JIS-L 1017 method of the Japanese Standards Association (JSA) such that the samples were fatigued. Subsequently, the rubber was removed from the samples, and then the strength after fatigue of the hybrid tire cord (dip cord) was measured. The strength retention rate defined by Equation 1 below was calculated based on the strength before fatigue and the strength after fatigue.

strength retention rate (%)=[strength after fatigue (kgf)/strength before fatigue (kgf)]100 <Equation 1>

[0141] Here, the strength before fatigue (kgf) and the strength after fatigue (kgf) were obtained by measuring the strength at break of samples having a length of 250 mm while tensing the samples at a cross-head speed of 300 m/min using Instron Tester (Instron Engineering Corp., Canton, Mass) according to ASTM D-885 testing method.

TABLE-US-00002 TABLE 2 Elongation at Elongation at 3% 5% 7% Dry heat Strength Strength specific load break LASE LASE LASE shrinkage retention rate (L.sub.A/L.sub.P) (kgf) (%) (%) (kgf) (kgf) (kgf) (%) (%) Example 1 1.000 24.1 2 9.3 6.9 12.5 18.9 1.02 90.3 Example 2 1.010 25.6 1.9 9.3 7.0 12.4 18.7 1.02 92.5 Example 3 1.010 24.6 2 8.9 6.8 12.6 18.8 0.96 96.4 Example 4 1.020 24.7 1.9 8.9 7.0 12.8 19.6 0.96 98.7 Example 5 1.025 24.2 1.7 7.2 7.9 15.0 22.9 0.89 95.1 Example 6 1.02 38.4 1.4 9.3 10.7 17.8 27.6 1.71 85.6 Example 7 1.025 45.1 0.9 8.8 14.9 23.6 35.4 0.89 86.4 Example 8 1.035 37.2 1.4 9.5 9.3 16.6 26.1 1.56 81.4 Example 9 1.00 38.3 1.4 8.9 12.1 19.3 28.7 1.44 80.2 Comparative 1.100 26.3 1.8 7.7 7.6 14.9 23.8 0.85 41.6 Example 1 Comparative 1.070 23.6 2.2 8.6 7.3 14.5 23.5 0.8 59.9 Example 2 Comparative 1.070 23.5 2.3 9.1 7.0 14.1 23.2 0.88 53.9 Example 3 Comparative 1.100 22.6 2.5 13.1 6.8 13.9 22.8 0.87 68.1 Example 4 Comparative 1.07 35.4 1.6 9.9 9.9 16.7 26.2 0.84 42.5 Example 5 Comparative 1.10 32.1 1.6 10.3 9.5 16.2 25.5 0.83 40.1 Example 6

[0142] Referring to Table 1 and Table 2, each of the hybrid tire cords manufactured according to Comparative Examples 1 to 6 has a strength retention rate of less than 70%. In contrast, it can be seen that each of the hybrid tire cords manufactured using the manufacturing method according to the embodiment of the present disclosure (Examples 1 to 9) has a strength retention rate of 80% or more. The hybrid tire cords according to Examples 1 to 9 having this physical property may be usefully applied to a high-performance lightweight tire.

[0143] In addition, it can be seen that each of the hybrid tire cords according to Examples 9 to 9 has 3% LASE of 8 kgf or more, 5% LASE of 15 kgf or more, and 7% LASE of 25 kgf or more, measured according to ASTM D885, in addition to a strength retention rate of 80% or more. The hybrid tire cords according to Examples 9 to 9 may be used as a reinforcement material for a high-pressure tire, and may be used particularly for a carcass of the high-pressure tire.