High modulus nylon 6.6 cords

Abstract

A dipped and heat-set high modulus nylon 6.6 cords having a tensile stress value between 1.2 and 2.0 cN/dtex at 4% elongation. The high modulus nylon 6.6 cords are used as reinforcement in shaped rubber composites. The minimum heat shrinkage of the cords is 4% and the maximum heat shrinkage thereof is 7%.

Claims

1. A two or three-ply dipped and heat-set polyamide 6.6 cord comprising: a plurality of polyamide 6.6 raw yarns; wherein the plurality of polyamide 6.6 raw yarns have a tensile stress value greater than 1.30 cN/dtex; wherein a stress value at 4% elongation of the polyamide 6.6 cord is higher than 1.2 cN/dtex and less than 2.0 cN/dtex, wherein a heat shrinkage of the polyamide 6.6 cord is higher than 4.0% and less than 7.0% determined at 177 C. under 0.045 g/dtex pretension with 2 minutes exposure time; wherein the tensile stress value is determined with a tensile tester according to ASTM D885-16.

2. The polyamide 6.6 cord of claim 1, wherein a stress value at 4% elongation of the raw yarn is preferably higher than 1.35 cN/dtex and less than 1.50 cN/dtex.

3. The polyamide 6.6 cord of claim 1, wherein the heat shrinkage of the polyamide 6.6 cord is preferably 5.0 to 6.5%.

4. The polyamide 6.6 cord of claim 1, wherein a total cord dtex of the polyamide 6.6 cord in is 300 dtex to maximum 4000 dtex.

5. The polyamide 6.6 cord of claim 1, wherein a twist factor of the polyamide 6.6 cord is 100 to 250; wherein the twist factor is calculated according to a following formula of:
twist factor=(t/mSQRT(tex/1000)).

6. The polyamide 6.6 cord of claim 1, wherein the tensile stress value of the plurality of polyamide 6.6 raw yarns is preferably between 1.35 and 1.60 cN/dtex at 4% elongation; wherein the tensile stress value is determined with a tensile tester according to ASTM D885-16.

7. The polyamide 6.6 cord of claim 1, wherein the twist factor of the polyamide 6.6 cord is preferably between 120 and 180; wherein the twist factor is calculated according to the following formula:
twist factor=(t/mSQRT(tex/1000)).

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) According to invention, in order to produce the high modulus cords, the high modulus raw nylon 6.6 yarns are used instead of regular lower modulus raw nylon 6.6 yarns which resulted in improved fatigue resistance.

(2) The tensile stress value at 4% of the said raw nylon 6.6 yarns is greater than 1.30 cN/dtex, preferably between 1.35 and 1.60 cN/dtex (determined with tensile tester according to ASTM D885-16)

(3) The high stretched cords having high modulus maintain their properties in bobbins, because they are not permitted to relax, and they are used in tire without experiencing significant relaxation (modulus drop).

(4) The high modulus cords in high stretched cord fabrics also maintain their properties in rolls, because they are not permitted to relax, and they are used in tire without experiencing significant relaxation (modulus drop).

(5) The tensile properties of the high modulus nylon 6.6 cords are determined after 24 hours conditioning on spool (without unwinding) under winding tension at 24 C. and with 55% relative humidity (ASTM D885-16). After conditioning, the cords are tested within 1 minutes after unwinding from the spool.

(6) In case of cord fabrics, the test tabbies are conditioned as tabby (without separating and cutting out the cords from tabby as fabric) under the same conditions as mentioned above. After conditioning, the cords cut out from the tabbies are tested within 1 minutes.

(7) The two and three-ply cords according to the invention have a stress at 4% elongation of 1.2 cN/dtex(30.6 g/dtex and 34 g/d modulus) to 2.0 cN/dtex(51 g/dtex and 56.7 g/d modulus) and thermal shrinkage at 177 C. of 4.0% to 7.0%.

(8) The stress at 4% elongation is determined according to the following formula:
Stress at 4% elongation(cN/dtex)=Tension at 4% elongation(cN)/linear density(dtex)

(9) The total nominal dtex of the cord is taken as linear density (e.g. 1400 dtex for 700 dtex/2 cord construction).

(10) The modulus values are calculated by multiplying the stress values at 4% elongation with 25 in order to find the needed stress value for 100% elongation.

(11) The thermal shrinkage of yarns and cords are determined with a Testrite heat shrinkage tester under a pretension of 0.045 g/dtex at 177 C. with 2 minutes exposure time.

(12) According to invention, the heat shrinkage of the cords are within the limits of 4% and 7%, preferably 5.0% and 6.5%.

(13) According to invention, the total nominal dtex of the cords can change between 300 and 4000 dtex.

(14) According to invention, in order to have optimum restraining force and bending fatigue resistance, the twist factors of the cord are adjusted between 100 and 250, preferably 120 and 180 according to the following formula;
Twist factor=(t/mSQRT(tex/1000)

(15) The high modulus nylon 6.6 cords can be used as reinforcement in pneumatic tires and mechanical rubber goods.

(16) Definitions:

(17) Dtex: The gramm weight of yarn having 10.000 meter length.

(18) Denier: The gramm weight of yarn having 9.000 meter length

(19) g/d: Gramm/denier

(20) g/dtex: gramm/dtex

(21) Linear density: Weight per unit length as g/dtex or g/d(denier)

(22) Modulus at 4% elongation: (Stress at 4% elongation)25 as g/d or g/dtex

(23) L5 Modulus: Modulus at 5% elongation, (stress at 5% elongation)20 as g/d or g/dtex

(24) Tenacity: Breaking force/total linear density(g/dtex)

(25) Twist: Twist per meter(t/m or tpm)