KR100602282B1 - Polyester fiber, preparation thereof and dipped cord - Google Patents

Abstract

According to the present invention, the main repeating unit of the molecular chain is ethylene 2,6-naphthalene dicarboxylate, the minor repeating unit is ethylene terephthalate, and melt spinning the co-polyester having an intrinsic viscosity of 0.7 or more, and having a birefringence of 0.08 or more and a crystallinity of 10 A method for producing a polyester fiber and a minimum strength of 5.0g / d, characterized in that the unstretched yarn which satisfies at most%, the elongation at least 10%, and the glass transition temperature of at least 95 ° C is prepared, followed by stretching and heat treatment. Drawn yarns satisfying birefringence of at least 0.10, crystallinity of at least 15%, and cutting elongation at least 10%, and strength of at least 5.0 g / d, cutting elongation of 10%, medium elongation of 5.5%, dry heat shrinkage of 3.0% or less And a treatment code satisfying the shape stability index 8.0 or less at the same time, the high strength fiber and the treatment cord of the present invention have excellent thermal shape stability. Below it is possible to solve the problems such as deterioration of physical properties at high temperature generated in the tire cord.

Description

Polyester fiber, preparation method and treatment cord

FIELD OF THE INVENTION The present invention relates to polyester fibers, in particular polyester fibers or filament yarns of poly (ethylene 2,6-naphthalene dicarboxylate) copolymers having excellent thermal morphological stability and high strength that are useful for tire cords and their manufacture Method, processing code.

Polyester fibers mainly composed of nylon and polyethylene terephthalate, which are mainly used in automobile tire cords, are generally easy to manufacture and inexpensive, while high temperatures of 70 to 220 ° C., for example, The high shrinkage ratio at the temperature of the tire and particularly the temperature during the tire manufacturing process during driving of the tire is not only difficult in the manufacturing process of the tire but also has a disadvantage in that the shape stability of the tire is poor during the driving. Due to this shape stability disadvantage, nylon tires used in heavy trucks, buses, etc., spot-flat phenomenon occurs. On the other hand, most of the high-speed car tires are still using rayon fibers with excellent thermal form stability at high temperatures, but the demand is gradually decreasing due to environmental barriers in the manufacturing process and relatively lower strength than other fiber materials. .

In addition, various kinds of high modulus low shrinkage polyethylene terephthalate filament yarns used as yarns for tire cords are known and are commercially used in various processes. However, these polyethylene terephthalate filament yarns show limitations in the development of morphological stability at high temperatures due to the inherent properties of the polymer (glass transition temperature, melting temperature, etc.).

In particular, heat generation during high-speed driving is the case that tire cords manufactured by conventional poly (ethylene terephthalate) filament yarns have a sharp decrease in elastic modulus, as well as the inherent deterioration of the inherent properties of the cord due to the repeated movement of tension and shrinkage while driving. There are disadvantages.

Therefore, the present invention is to provide a novel polyester fiber, a method for manufacturing the same and a treated cord using the same that can solve all the problems of the prior art as described above as a technical problem.

In the study of the present inventors to solve the above problems by using a poly (ethylene 2,6-naphthalene dicarboxylate) or its copolymers, such as a decrease in physical properties that can be caused at high temperatures of existing nylon, polyethylene terephthalate fibers The present invention has been succeeded in developing a high strength fiber and processing cord having excellent thermal form stability that can solve the problem.

Therefore, according to the present invention, the main repeating unit of the molecular chain is ethylene 2,6-naphthalene dicarboxylate, the minor repeating unit is ethylene terephthalate, and the melt spinning of the copolyester having an intrinsic viscosity of 0.7 or more, the birefringence of 0.08 or more, the degree of crystallinity Provided is a method for producing a polyester fiber, characterized in that the unstretched polyester, characterized in that it satisfies at least 10%, elongation at least 10% and glass transition temperature 95 ℃ or more at the same time, followed by stretching, heat treatment. do.

In addition, according to the present invention, the main repeating unit of the molecular chain is ethylene 2,6-naphthalene dicarboxylate, the minor repeating unit is ethylene terephthalate, and the copolymer has a intrinsic viscosity of 0.7 or more, and has a minimum strength of 5.0 g / d. The polyester stretched yarn which simultaneously satisfy | fills birefringence 0.10 or more, crystallinity 15% or more, and cut elongation 10% or more simultaneously is provided.

According to the present invention, the main repeating unit of the molecular chain is ethylene 2,6-naphthalene dicarboxylate, the minor repeating unit is ethylene terephthalate, and the copolymer polyester having intrinsic viscosity of 0.7 or more, strength of 5.0 g / d or more, 10% or more cut elongation, 5.5% or less intermediate elongation (elongation under 4.5 g / d load), 3.0% or less dry heat shrinkage (measured under conditions of 177 ° C x 2 min x 0.03 g / d load) and shape stability index (medium elongation) + Dry heat shrinkage) A polyester treatment cord is provided which simultaneously satisfies 8.0 or less.

Hereinafter, the present invention will be described in more detail.

The polyester fiber of this invention uses co-polyester whose main repeating unit of a molecular chain is ethylene 2,6-naphthalene dicarboxylate, and a minor repeating unit is ethylene terephthalate as a raw material. Preferably, the copolyester is at least 90 mol% of ethylene 2,6-naphthalene dicarboxylate and up to 10 mol% of ethylene terephthalate copolymer of the total repeating units of the molecular chain.

For copolymers where ethylene 2,6-naphthalene dicarboxylate is less than 90 mol% of the total repeating units of the molecular chain or greater than 10 mol% ethylene terephthalate in the total repeating units of the molecular chain, It is difficult to expect the thermal morphological stability required by the present invention by causing a sharp decrease in the glass transition temperature and the melting temperature. In addition, when the raw material resin has an intrinsic viscosity of 0.70 or less, it is good in terms of morphological stability, but it is not preferable because the strength decreases and the toughness decreases.

The polyester unstretched yarn according to the present invention is produced so as to simultaneously satisfy birefringence of 0.08 or more, crystallinity of 10% or less, cutting elongation of 10% or more, and glass transition temperature of 95 ° C or more.

Preferably, the non-stretched yarn having the above characteristics is manufactured by melting the raw material resin, extruding it into multifilament through the spinneret, and passing the heating tube installed under the detention, delaying cooling, and then cooling and solidifying it. At this time, the spinning speed is preferably less than 2,000mpm.

The unstretched yarn obtained when the spinning speed is set too high proceeds to crystallization due to the orientation of molecular chains during spinning, resulting in high birefringence and crystallinity of the unstretched yarn, which makes it difficult to give an appropriate stretch ratio during the subsequent stretching process. High strength expression becomes difficult, especially economical manufacturing is difficult.

When the undrawn yarn of the above characteristics is drawn, it is made of a drawn yarn having a minimum strength of 5.0 g / d or more, a cut elongation of 10% or more, a birefringence of 0.10 or more, and a crystallinity of 15% or more. Preferably, the drawn yarn of the above-described characteristics may be prepared by drawing and heat-treating at a draw ratio of 1.5 times or more, 5.5 times or less, stretching temperature of 120 ° C. or more and 250 ° C. or less after the production of the undrawn yarn. For example, in the case of two-stage drawing, it is preferable that the unstretched yarn is continuously drawn in one-stage drawing at 120 to 150 ° C. and the two-stage drawing at 180 to 250 ° C., but the total draw ratio is 1.5 or more and 5.5 times or less. The proper draw ratio enables the provision of basic properties of the drawn yarn which can be applied with a tire cord, and the first stage stretching temperature is suitable near the glass transition temperature for imparting fluidity during stretching of the molecular chain, and the second stage stretching temperature is fiber after stretching. The temperature should be given around the progress of crystallization to fix the structure.

In the case of tire coding the drawn yarn of the present invention, for example, the drawn yarn is made of cord (or cord paper) and then made of treated cord (or deep cord) impregnated in rubber liquid to give a bonding force with the rubber matrix. .

The treated cord made of the drawn yarn of the present invention has a strength of 5.0 g / d or more, a cut elongation of 10% or more, an intermediate elongation (elongation under a load of 4.5 g / d) of 5.5% or less, and a dry heat shrinkage rate (177 ° C × 2 minutes × 0.03 g / d) It is desirable to simultaneously satisfy 3.0% or less and form stability index (medium elongation + dry heat shrinkage) 8.0 or less.

As an example of a method of making the treatment cord of the present invention, a twisted yarn having a twist number of two or more filaments of 9 × 9 per inch is first stretched at 240 ° C. for 40 seconds after being immersed in a diisocyanate immersion liquid, and a secondary Treatment cords of the above characteristics can be prepared by immersing in rhoresorcinol-formaldehyde-latex solution and relaxing for 60 seconds at 240 ° C.

The polyester fiber according to the present invention as described above is very suitable as a material of the tire cord because it has the advantage of overcoming the problem of poor shape stability at high temperature generated in conventional nylon, polyethylene terephthalate fiber.

Features and other advantages of the present invention as described above will become more apparent from the following examples. However, the present invention is not limited to the following examples.

Physical properties presented herein are measured by the following method.

* Intrinsic viscosity (IV): measured by dissolving in ortho-chlorophenol using an Ostwald viscometer.

* Strength and elongation at break: measured by Instron's fast-extension type tenxyl strength tester according to JIS-L1017 method.

* Dry heat shrinkage: The length (L1) of the sample measured at 20 g load after 24 hours at 25 ° C and 65% RH, and the length of the sample treated under 0.03 g / d load at 177 ° C for 2 minutes (L2). ) Is obtained by measuring (TR method).

Dry heat shrinkage ratio = (L1-L2) / L1 × 100.

* Intermediate elongation: Change in elongation length under 4.5g / d load.

* Shape stability index: moderate elongation + dry heat shrinkage rate.

* Birefringence: The birefringence (△ n) is calculated by the following equation. The retardation R is obtained from an interference chromaticity by a sample by attaching a berek compensator to the polarizing microscope.

Where d is the thickness of the sample (mm)

* Crystallinity: The crystallinity (X _c ) is calculated by the following equation.

Where ρ: density of yarn (g / cm 3)

ρ _a : 1.445

ρ _c : 1.335

Density (ρ) is measured using a density gradient column using normal heptane and carbon tetrachloride at 25 ℃.

<Example and Comparative Example>

1. Manufacture of undrawn yarn

Through solid phase polymerization, polymers with intrinsic viscosity of 0.72 and 87 mol% and 95 mol% of ethylene 2,6-naphthalene dicarboxylate (EN), the main repeating units of the molecular chain, were melted at 310 ° C. to 0.6 diameter. It was extruded with the spinneret which has 144 detent holes which are mm and L / D 2.0. Directly below the detention, a heating tube was installed with a length of 120 mm and a temperature of 350 ° C., with a relative humidity of 95% and a cooling atmosphere of 25 ° C. under the heating tube. The discharge amount was adjusted so that the total fineness of the drawn yarn was 1,000 denier. However, the spinning speed was applied differently as shown in Table 1. The birefringence, crystallinity, elongation at break, and glass transition temperature of the obtained non-drawn yarn were measured, and the results are shown in Table 1.

Experiment number Raw material Flux (m / min) Undrawn Shrine EN (mol%) Tg (℃) Birefringence Crystallinity (%) Elongation at break (%) Tg (Q.R) (° C) A-Ⅰ 95 116.8 500 0.010 4.8 16.3 117.2 A-Ⅱ 95 116.8 1500 0.029 6.9 13.4 115.9 A-Ⅲ 95 116.8 2800 0.083 11.1 8.2 116.8 B-Ⅰ 87 94.3 500 0.009 4.2 16.2 93.9 B-Ⅱ 87 94.3 1500 0.027 6.7 12.4 93.7 B-Ⅲ 87 94.3 2800 0.083 10.8 8.6 94.3

2. Manufacture of Drawing Yarn

The stretched yarn was prepared by stretching and heat-treating in two stages in succession to the spinning production of the above non-drawn yarns (A-I, A-II, A-III). Spinning speed, draw ratio, and temperature conditions are as specified in Table 2 below. The strength, birefringence, crystallinity, and elongation at break of the obtained non-drawn yarn were measured, and the results are shown in Table 1.

Experiment number Miyeon Shrine Total draw ratio Drawing temperature (1st / 2nd stage) (℃) Drawing material Strength (g / d) Cutting elongation (%) Crystallinity (%) Birefringence (%) A-Ⅰ-1 A-Ⅰ 4.87 85/235 4.8 9.2 21.4 0.138 A-Ⅰ-2 A-Ⅰ 4.87 125/175 4.6 10.8 14.2 0.127 A-Ⅰ-3 A-Ⅰ 4.87 125/235 5.2 10.5 18.7 0.149 A-II-1 A-Ⅱ 3.68 125/175 4.8 9.4 18.9 0.126 A-II-2 A-Ⅱ 3.43 125/235 5.5 10.3 18.6 0.132 A-II-3 A-Ⅱ 3.68 125/235 5.8 10.2 19.8 0.138 A-III-1 A-Ⅲ 1.47 85/235 4.7 14.4 21.8 0.124 A-III-2 A-Ⅲ 1.47 125/175 4.5 13.8 20.8 0.129 A-III-3 A-Ⅲ 1.47 125/235 4.8 15.7 21.9 0.124 A-III-4 A-Ⅲ 1.72 85/235 5.7 8.8 23.9 0.139 A-Ⅲ-5 A-Ⅲ 1.72 125/175 5.5 8.5 23.4 0.148 A-III-6 A-Ⅲ 1.72 125/235 5.7 9.5 25.8 0.144

3. Manufacturing of Processing Code

The stretched yarns were prepared as twisted yarns having a twist number of 9 × 9 per inch of twisted water, and the stretched yarns were stretched at 240 ° C. for 40 seconds after being immersed in diisocyanate immersion liquid, and then resorcinol-formaldehyde- It treated with a latex solution and relaxed for 60 seconds at 240 ℃ to prepare a treatment cord. The strength, cutting elongation, intermediate elongation, dry heat shrinkage, and shape stability index of the prepared treatment cords were measured, and the results are shown in Table 3.

Experiment number Unpainted Shrine Drawing company Treatment code property Strength (g / d) Elongation at break (%) Medium Elongation (%) Dry heat shrinkage (%) Shape stability index (%) D1 A-Ⅰ A-Ⅰ-1 4.68 12.1 5.6 3.1 8.7 D2 A-Ⅰ A-Ⅰ-2 4.42 13.8 5.3 3.1 8.4 D3 A-Ⅰ A-Ⅰ-3 5.11 18.8 5.3 2.6 7.9 D4 A-Ⅱ A-II-1 4.61 11.5 5.1 2.8 7.9 D5 A-Ⅱ A-II-2 5.27 14.4 5.3 2.3 7.6 D6 A-Ⅱ A-II-3 5.49 14.4 5.3 2.4 7.7 D7 A-Ⅲ A-III-1 4.54 16.6 5.6 2.7 8.3 D8 A-Ⅲ A-III-2 4.29 16.2 5.6 2.7 8.3 D9 A-Ⅲ A-III-3 4.63 16.8 5.3 2.8 8.1 D10 A-Ⅲ A-III-4 5.43 9.2 4.8 2.3 7.1 D11 A-Ⅲ A-Ⅲ-5 5.41 9.0 4.7 2.3 7.0 D12 A-Ⅲ A-III-6 5.63 9.7 5.2 2.2 7.4

As can be seen from the above experimental results, according to the present invention, the main repeating unit of the molecular chain is ethylene 2,6-naphthalene dicarboxylate, the minor repeating unit is ethylene terephthalate, and has a intrinsic viscosity of 0.7 or more. Since the birefringence of 0.08 or more, the crystallinity of 10% or less, the elongation at least 10% and the glass transition temperature of 95 ℃ or more at the same time can be produced undrawn yarns (A-I, A-II), from the minimum Manufactured stretched yarns (A-I-3, A-II-2, and A-II-3) which simultaneously satisfy strengths of 5.0 g / d or more, birefringence of 0.10 or more, crystallinity of 15% or more, and elongation at least 10%. From the drawn yarns, the treatment cord (D3, D5, D6) can be manufactured.

The high-strength fibers and treated cords of the present invention as described above are excellent in thermal form stability and can solve problems such as deterioration of physical properties at high temperatures generated in conventional tire cords.                     

Claims (5)

The main repeating unit of the molecular chain is ethylene 2,6-naphthalene dicarboxylate, the minor repeating unit is ethylene terephthalate, melt spinning a copolyester having an intrinsic viscosity of 0.7 or more, and having a birefringence of 0.08 or more, crystallinity of 10% or less, and cleavage A method of producing a polyester fiber, characterized in that after the polyester unstretched yarn that satisfies at least 10% elongation and glass transition temperature of 95 ℃ or more at the same time and subsequently stretched, heat treatment. The method of claim 1, wherein the spinning speed is less than 2,000mpm. The method of claim 1, wherein the stretching is performed at a total draw ratio of at least 1.5 times, at most 5.5 times, at a drawing temperature of at least 120 ° C and at most 250 ° C. The main repeating unit of the molecular chain is ethylene 2,6-naphthalene dicarboxylate, the minor repeating unit is ethylene terephthalate, copolyester with an intrinsic viscosity of 0.7 or more, minimum strength 5.0g / d or more, birefringence 0.10 The polyester stretched yarn which simultaneously satisfies at least 15% of the crystallinity and at least 10% of the elongation at break. The main repeating unit of the molecular chain is ethylene 2,6-naphthalene dicarboxylate, the minor repeating unit is ethylene terephthalate, copolyester with an intrinsic viscosity of 0.7 or more, strength of 5.0 g / d or more and elongation at least 10%. It satisfies both the median elongation (elongation under 4.5g / d load) of 5.5% or less, dry heat shrinkage (measured under conditions of 177 ° C × 2 minutes × 0.03g / d load) of 3.0% or less and the shape stability index of 8.0 or less Polyester processing cord made into.