JPS6197439A - Polyester cord - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a high toughness polyester cord that is particularly suitable for industrial use.

b. Prior art Because polyester fibers have various excellent properties, they are widely used not only for clothing but also for industrial purposes. Polyester fibers, which have particularly high strength and excellent dimensional stability, are useful in industrial applications, and have been used not only for tires but also for non-tire applications and industrial asset applications. However, recently, increasingly high performance is required, such as conveyor belts.

For rubber hose applications, we need even lower shrinkage due to dimensional stability during molding! ! It is claimed to have excellent durability and fatigue resistance under harsh usage conditions.

Furthermore, in applications such as curing sheets, ropes, and fishing nets, high toughness with high elongation is required.

Currently, in these fields, rayon fibers and vinylon fibers, which have a long history, are commonly used, and polyester fibers are also beginning to be used. However, polyester fibers have high strength, low yield, and insufficient durability and fatigue resistance. From this point of view, if these special improvements are made, polyester fibers with low cost/par 7 ounces will become increasingly popular as industrial materials.

In general, in order to produce high toughness polyester fibers with high elongation, a high 1 degree polyester as disclosed in Japanese Patent Publication No. 5B-5g524 is used, molecular orientation is suppressed during the spinning stage, and molecular orientation is suppressed during the drawing stage. A method is known in which the stretching ratio is increased as much as possible, and then sufficient relaxation heat treatment is performed at a high temperature. However, with this method, although it is possible to obtain drawn fibers with high elongation, high toughness, and low shrinkage, it is difficult to twist, knit, and heat-treat under tension. If high-order processing is performed, it will not be possible to obtain a product with low shrinkage and high elongation. On the other hand, in order to reduce the shrinkage rate, for example,
A method using a low polymerization degree polyester as disclosed in Japanese Patent No. 58028 is known. However, with this method, it is difficult to obtain products with high strength and toughness.

In addition, in the above two methods, both methods have low fatigue resistance. or not obtained.

In order to improve fatigue resistance with low yielding properties, for example, Japanese Patent Application Laid-open Nos. 53-58031 and 53-58032 disclose methods that reduce the degree of molecular orientation of drawn yarn and reduce work loss. Polyester fibers and methods for producing the same aimed at improving fatigue properties have been proposed. This method involves rapid cooling in a gas atmosphere of 10 to 60°C under the spinneret. However, in order to achieve high strength, the elongation is extremely low because the yarn is stretched to the point of breaking, and the yarn breaks frequently during stretching, making stable production difficult.

Means to solve the C0 problem The inventors have attempted to overcome these drawbacks.

As a result of extensive research, we found that using polyester wire-drawn fibers that have a specific degree of polymerization, have a higher degree of orientation than ordinary undrawn fibers, and have sufficient elongation at break.
It has been found that a polyester hood with good stretchability and the desired properties of PJ1 can be obtained. In other words, it has high elongation, high toughness, and good fatigue resistance. Surprisingly, when this cord is further heat-treated under industrial tension, it has low shrinkage and increased toughness, making it a polyester that is particularly suitable for non-tire and industrial property applications. The present invention was achieved by discovering that this can be a code.

That is, the present invention uses ethylene terephthalate as the main component of the repeating structural unit of the molecular chain, and has a twist coefficient of 450-13.
50 is a polyester cord in which the first twist and the first twist are applied, the stress increment near the cutting point in the load 1-load elongation curve is zero or negative, and the breaking elongation is 15% or more. This is related to.

The polymer constituting the polyester cord of the present invention is a polyester containing 90 mol % or more, preferably 95 mol % or more of ethylene terephthalate repeating units in the molecular chain. As such polyester, polyethylene terephthalate is suitable, but other copolymer components may be included in a proportion of less than 10 moles, preferably less than 5 moles S. An example of such a copolymer component is isophthalic acid! Examples include naphthalene dicarboxylic acid, adipic acid, oxybenzoic acid, diethylene glycol, phosphoric acid, trimellitic acid, and pentaerythritol. Furthermore, these polyesters may contain additives such as stabilizers and color cleaners. Further, it is preferable that such a polyester cord has an intrinsic viscosity of 0.80 or more as determined from a μρ phenol bath solution at 25° C. in order to obtain high toughness.

The polyester cord of the present invention has a twist coefficient of 450 to
It is essential that the first twist and/or final twist of 1350 is applied.

Here, the twist coefficient is defined by the following formula.

K=T, f'5 T is the number of upper m per 10 cm length of the cord. Even if the treatment is applied, the desired elongation and high toughness cannot be obtained, and if the elongation exceeds 1350, the elongation increases but the strength decreases, and the toughness decreases and even after subsequent high-order treatment, the elongation and toughness are lowered. It is inappropriate because it does not produce a shrinkable product. The twist coefficient should be 450 to 1350, taking into account further processing depending on the application.

Due to its purpose, the polyester cord of the present invention has performance that is significantly different from conventional cords in the shape of the unloading curve. That is, the increment of stress near the cutting point in the loader-carrier curve is zero or negative. In addition, the load 1-load elongation curve is JI
Measured in accordance with SL1017-1963 (5, 4,). The characteristic load-unloading curve of this polyester cord is shown in FIG. 1 in comparison with a conventional cord. In FIG. 1, A, N, and B are the cutting points of the present invention cord and the conventional cord, and slope A' and slope B' indicate the increment of stress (tentatively named terminal modulus) near each cutting point. As is clear from FIG. 1, the polyester cord of the present invention has a negative terminal modulus, and has a percentage sign significantly different from that of the conventional positive modulus. If the terminal modulus is negative, not only the elongation will significantly increase due to tension treatment and/or heat treatment in subsequent high-order processing, but also the strength will increase, the toughness will increase significantly, and the material will have low shrinkage. Fatigue resistance is also improved. If the same treatment as the conventional cord Ic is applied, both the strength and elongation will decrease, the toughness will decrease, and the shrinkage rate will increase.

The polyester cord of the present invention has the above-mentioned characteristic load-
In addition to the unloading curve, it is necessary that the cutting elongation is 15% or more. If it is less than 1596, even if it exhibits the above-mentioned characteristic load-unloading curve, it will not be possible to obtain the desired high toughness with high elongation through high-order processing. The polyester cord preferably has a cutting strength of 5.5 g/de or more to obtain high toughness for the final intended use. Furthermore, in order for the polyester cord of the present invention to exhibit low shrinkage upon high-level processing, it is preferable that the dry heat shrinkage rate at 150°C is 10% or less.

In addition, the dry heat shrinkage rate is JIS L1017-1963 (
5, 12).

The polyester cord of the present invention can be obtained, for example, by the following method. In other words, undrawn fibers having a specific degree of polymerization and a sufficient degree of elongation at break because they do not have a high degree of orientation compared to ordinary undrawn fibers are used and drawn at a specific draw ratio. The fibers are then heat treated to form drawn fibers. Then this stretching l
#! A polyester cord is obtained by twisting the yarn at the predetermined twist coefficient according to a conventional method.

More specifically, a polyester containing ethylene terephthalate as a main repeating unit and having an intrinsic viscosity of 0.80 to 0 or a polyester having an intrinsic viscosity of 0.7 to 0.9 is reacted with a polymerization degree accelerator. It is melted and transported by a conventional method 7, and then it is drawn from a spinneret until the fineness after drawing becomes 1 to 20 degrees (discharged into a yarn, and immediately after discharge, it is rapidly cooled or kept warm at a temperature below the melting point and up to the temperature at which crystallization starts). or in a heated atmosphere at a temperature above the melting point.

Expose for a certain period of time to perform delayed cooling. Thereafter, the yarn is cooled and solidified, and it is useful to cool and solidify it under neutral conditions.

x ．． Birefringence of 0.02 to 0.07, preferably 0.03 to 0.0
7, more preferably undrawn fibers with a breaking elongation of 0.035 to 0.050 and 100 to 200%. The oil agent can be applied by any method such as an oiling p-lab method or a spray method. Further, as the oil agent, any textile oil agent can be applied as needed. At this time, in fields where adhesion with rubber is important as a fiber application, it is useful to apply a surface treatment agent to impart adhesion.

Next, the upper gt=undrawn fibers are subjected to drawing heat treatment.

Even if this drawing heat treatment step is performed continuously following spinning,
After winding it up, you can take another step. In the case of continuous drawing after spinning, the previously proposed patent application 1983-8
8927 (; Publication No. 1 Soft). In addition, in the case where the yarn is wound up once after spinning and then stretched, the method of No. 19 of Publication No. This can be carried out in accordance with the method described in Japanese Patent No. 57-189094. The latter stretching method is preferred in terms of reducing stretching strain during stretching and heat treatment strain. That is, the undrawn fiber is preheated at a temperature of Tg+15 to Tg+50°C (here, Tg is the glass transition temperature of the undrawn fiber) for at least 0.5 seconds, and then drawn in the first stage at a draw ratio of 759 or less of the total draw ratio. The birefringence is set to 1.2 to 3.3 times the birefringence of the undrawn fiber. Next, the single-stage drawn yarn is further subjected to multi-stage drawing heat treatment. At this time, if the elongation is large and toughness is required, after the first stage drawing, the second stage stretching is carried out at the actual temperature in the range of -50°C to the melting temperature -1)0°C, and then If necessary, the melting temperature of the fiber as the actual yarn temperature after multi-stage drawing
50℃ to melting temperature -1) 0.4 to 1.5 in the range of 0℃
It is preferable to carry out a relaxation heat treatment of 7% or less while holding the film for 2 seconds, so that the stretching ratio is 85 or less of the substantially total stretching ratio.

In addition, in order to increase the heat resistance of the polyester cord in rubber and improve the durability of products for various uses, the terminal carboxyl group content of the polyester fiber should be set to 20 equivalents/106 grams of polymer or less, preferably 15 equivalents/M/106 grams of polymer. It is particularly preferable to do the following. For this purpose, the following various methods can be adopted.

That is, as in 0j Japanese Patent Publication No. 44-2791) (method 12 of reacting polyester in a melted state with f6 phenyl glycidyl ether), as in Japanese Patent Publication No. 45-41235, reacting a linear polyester carbonate with polyester in a molten state. Method (3) As described in Attachment 1@47-12891 (Method of reacting polyester with ethylene oxide 141%) For glycol ester of oxalic acid, polyester is reacted with oxalic acid polyester as in Publication No. 48-35953 (5g Special Publication Showa 48-4171
(6) Method of reacting polyester with diaryl oxalates and/or diaryl malonates and diaryl carbonates as in Japanese Patent Publication No. 49-5233 (7) A method of reacting carbodiimide with BolJ ester as in U.S. Pat. It is possible to adopt it at any time. In particular, it avoids the color of the resulting laminated material, does not cause foaming due to decomposition of the saturating agent during molding, does not reduce the degree of polymerization, and reduces the amount of terminal carboxyl groups to 1.
A method of reducing the amount to 5 equivalents/106 grams of polymer or less is preferred. Next, this polyester fiber is subjected to the desired first twist and/or final twist described above in accordance with a conventional method.

The polyester cord of the present invention can be used as it is or after being knitted or woven, but depending on the application, it may be further heat-treated under tension or heat-treated under tension after being treated with an adhesive to give it adhesive properties with rubber. . When pasting under tension, it is usually applied at a temperature of 200 to 260°C under tension of 1% or more to 5 points.
Heat treatment for 0 to 240 seconds. The resulting cord has sufficient strength, i.e., 6 &
/de or more, elongation is 13 parts or more, toughness (strength Xv'
(li) 25 or more, sufficiently low tightness, ie, dry heat shrinkage rate at 150°C of 4.096 or less, 1.5. fJ/de high modulus with elongation under the load of 2.5% or less and bending angle extension 9
Shows tube fatigue resistance with a tube life of 300 minutes or more at 0°.

d. Effects As mentioned above, the polyester cord of the present invention has toughness,
Due to its excellent shrinkage, modulus and iron resistance, it is suitable for various leakage structures such as V-belt, μ-edge belt, V-belt, IJV-belt, I''-bearing belt, Timing-<
Luto.

It is extremely useful for reinforcing structures such as natural rubber such as Polymax and synthetic materials.

e. Examples The present invention will be explained in further detail with reference to Examples below. In addition, all parts in Examples indicate parts by weight.

Example 97 parts of dimethyl terephthalate, 6 parts of ethylene glycol
9 parts of calcium acetate monohydrate, and 0.025 parts of antimony trioxide were placed in an autoclave, and after removing methanol produced as a result of transesterification at 80 to 230°C, H, P.O.
Add 0.05 part of 50% water treatment solution and heat to 280°C.
After about 1 hour, the pressure in the reaction system was reduced to 0.2 inl 1 g, and the pressure was reduced to 0.2 inl 1 g for 1 hour.
The polymerization reaction was continued for 0 minutes to obtain a polymer having an intrinsic viscosity of O, SO and a terminal carboxyl group content of 28 equivalents/10·g polymer.

100 parts of this polymer chip was triblended with 2,2'-bis(2-oxazoline) (CF) as shown in Table 1, and then melted and transported at about 300°C.
After the yarn is discharged from a spinneret having 0 spinnerets, the discharged yarn is blown with cooling air at 25° C. over 300 fins for 4. After cooling and solidifying with ON ml for 1 minute, an oil agent was applied with an oil ruler and then rolled up at a take-up speed of the first red recorder. The properties of the obtained undrawn fibers are shown in Table 1.

This undrawn fiber is supplied to a roll heated to 85°C,
After the first stage stretching between the take-up pole and the pulley, the second stage stretching was carried out through a gas bath heated to 325°C. Thereafter, heat treatment was performed using a heating ρ-ra at 130°C and a gas bath at 330°C. The total stretching ratio and the performance of the obtained drawn yarn are also listed in Table 1.

Next, three of these drawn yarns were twisted together to give two twists, and then the three yarns were combined to give an S twist to obtain nine 1]00deX polyester cords.

The performance of the obtained hood is also listed in Table 1.

Furthermore, these cords were dipped in adhesive (RFL liquid) and
A tension heat treatment was performed at 5° C. for 2 minutes.

The properties of this treated cord and its heat resistance and strength were measured by embedding it in rubber and vulcanizing it. The results are also listed in Table i1. In addition,
To measure heat resistance and strength, this treated cord was embedded in a vulcanization mold and accelerated vulcanization was performed at 170° C. and a pressure of 50 kg/ffl for 120 minutes.The treated cord was taken out and strength was measured.

[Brief explanation of the drawing]

FIG. 1 shows the load-back extension curve of a polyester hood. Song A1) l fi+ is the one of the present invention 1 curve (
2) is a conventional one. In the figure, A and B are the cutting points, and slopes A' and B' are the increments of stress near the cutting points. Procedural amendment July 5, 1982

Claims (3)

[Claims] (1) Ethylene terephthalate is the main component of the repeating structural unit of the molecular chain, and the twist coefficient is 450 to 1350 for the first twist and/or the first twist. A polyester cord whose increment is zero or negative and whose elongation at break is 15% or more. (2) The polyester cord according to claim (1), which has a dry heat shrinkage rate of 10% or less. (3) The polyester cord according to claim (1) or (2), which has a cutting strength of 5.5 g/de or more.