JPS588120A - High-performance polyester fiber - Google Patents

Abstract

PURPOSE:The titled fiber that contains a specific amount of ethylene terephthalate unit and has a specified intrinsic viscosity, optical birefringence, and terminal carboxyl concentration, thus being used to reinforce heavy-duty tires, because of its high humid heat reistance and yield resistance. CONSTITUTION:Polyester chips are coated with a compound active on carboxyls and subjected to melt spinning through a spinneret with many nozzles. The resultant fiber is drawn to produce the objective high-performance fiber that is composed 95-100mol% ethylene terephthalate unit and 5-0mol% other polyester unit and has an intrinsic viscosity of 0.8-1.20, an optical birefringence over 200X10<-3>, a filament fineness of 0.8-3 denier and a terminal carboxyl concentration of lower than 25eq/10<6>g. The resultant fiber shows low reduction in its tenacity, even when twisted strongly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyester fiber suitable for reinforcing fibers for tires for heavy vehicles, and more particularly to a high-strength polyester fiber with improved heat resistance and fatigue resistance.

Polyester fibers have a large initial modulus and good dimensional stability, and are widely used as rubber reinforcing cords for tire boards, etc. Due to their particularly high initial modulus, they are used as reinforcing cords for passenger car tires. suitable for

Currently commercially available polyester fibers for rubber reinforcement are
- Made of high polymerization degree polyester with an intrinsic viscosity of 0.9 or more as disclosed in the 78SHI bulletin, the multilayer folded book has a high orientation degree of 20OX10-''sll, 8, S11/d
~9. The main material is polyester fiber having a strength of Sjl/d. However, this commercially available polyester fiber for rubber reinforcement exhibits a high strength I [t-] in raw yarn, but it has a high strength when twisted under the required number of twists of 11I19 and ply twisted to form a so-called raw cord. The disadvantage is that the strength of the cord is lower than that of nylon fiber for rubber reinforcement. Furthermore, when commercially available polyester fibers for reinforcing rubber are exposed to high temperatures in the presence of moisture, their strength tends to decrease due to hydrolysis of the polyester. Therefore, problems such as a decrease in the strength of the polyester cord are likely to occur during the rubber vulcanization process, tire cord production, and during vehicle running. Another disadvantage is that commercially available polyester fiber wires for rubber reinforcement have poor fatigue resistance due to large hysteresis loss.
Has 4. In this way, commercially available polyester fibers for rubber reinforcement have problems in strength, numbing heat resistance, and fatigue resistance.
Therefore, it is not applicable to tires for heavy vehicles such as trucks and passes that are subject to high loads and reach high temperatures, and is rarely used for this purpose. Table IK below compares the performance of current heavy vehicle tire cords (nylon) and current commercially available polyester tire cords. On the other hand, it is known that the terminal carboxyl group of polyester acts as a catalyst for the hydrolysis layer of polyester, and it is also known that the temperature and heat resistance of polyester fibers is improved by reducing the degree of terminal carboxyl group loss. 9. Polyester fibers with a reduced terminal carboxyl group concentration have also been proposed (for example, see Bulletin No. 1855-9091). K was not suitable for use as a tire coat 2 for high-volume vehicles due to lack of improvements in #l and fatigue resistance. In addition, %l111183-polyester fiber with improved fatigue resistance has been shown.9 However, this fiber is used as a tire coat for high-volume vehicles without the improvement of strong WL strength and temperature resistance. Therefore, the object of the present invention is to provide a polyester fiber which has improved strength, heat and humidity resistance, and fatigue resistance, and which can be used as a tire cord for heavy-duty vehicles such as Kuya buses. What we decided to do: 1) As a result of our intensive research into achieving this goal, we found that the concentration of terminal carboxyl groups in the polyester that forms fibers [t! The present invention was achieved by discovering that the problem can be solved all at once by reducing the polyester fiber to 5 eq/xg@II or less and making the single fiber t of the polyester fiber 3 denier or less. The high-performance polyester fiber is made of a polyester in which 5 to 100 moles of ethylene terephthalate units and the remaining po, s to 0 moles are ester units, and the ffi of the polyester is viscous.
7! IX 0.8 to 1.2, multilayer folded book is 200 x 101 or more, single yarn fineness is 0.8 to 3 denier, and terminal carboxyl group concentration t of polyester is 25 eq/10 @, 9
It is characterized by the following:

In the present invention, in order to form fibers, polyester is 95 to 1
00 moles must be ethylene terephthalate units and the remaining 5 to 0 moles must be other ester units. If the ratio of other ester units exceeds 5 moles, the heat setting property of the polyester fiber will deteriorate, and as a result, the cord obtained from it will have poor dimensional stability against heat even after the heat treatment process, and will be used for rubber reinforcement. It's impossible.

V to improve dimensional stability against heat and obtain high strength fibers
Most preferred is polyethylene terephthalate consisting essentially of 1004 ethylene terephthalate units. The polyester used in the present invention may be polymerized by any known polymerization method, and may contain various common additives such as matting agents and stabilizers.

In addition, in the present invention, the intrinsic viscosity of polyester is 0.8
It needs to be between 0 and 1.20. If the intrinsic viscosity is less than 0.80, there is a limit to the strength of the raw yarn that can be used for diaphragm no matter how high the birefringence me, and a strength of 41N:1 is suitable for the level required for heavy vehicle tires. When the m viscosity exceeds 1.20 [-, the melt viscosity of the polyester melt is extremely high, making it difficult to flow and normal melt spinning is impossible. A preferable range of intrinsic viscosity is 0.80 to 0.95. In addition, in the present invention I/c, the multilayer folded book of fibers is 200
h0 birefringence, which must be 10-" or more, is a measure of the degree of molecular orientation; if it is less than 200 Even if the fineness is in the range of 10.8 to 3 deniers, the strength of the cord reaches the level for heavy-duty vehicle tires. Considering stable production, the range of multi-layer folded cords is 200Xi G-" to 210X 10-"'e&,
6° Furthermore, in the IC of the present invention, the single yarn fineness of the polyester fiber must be 0.8 to 3 deniers. By setting the single yarn fineness within this range, the strength and fatigue resistance of the cord can be brought to the level required for heavy vehicle tires.

Figure 1 is a graph showing the change in strength due to twisting. As is clear from this figure, the degree of strength reduction due to twisting depends on the single yarn fineness, and the smaller the single yarn fineness is, the smaller the strength decrease is. Furthermore, the smaller the single yarn fineness, the more advantageous the fatigue resistance. However, in a range where the single yarn fineness exceeds 3 denier, no matter how much the strength of the yarn is increased, the strength of the cord will not exceed the 500 twists/cumulative twist rate commonly used for rubber reinforcing polyester fibers, which is necessary for heavy vehicle tires. It does not meet the standards and its fatigue resistance is insufficient. Furthermore, in a range where the single yarn fineness is less than 0.8 denier, the number of single yarns of polyester fiber is extremely large (for example, 1250 when the total fineness is 1000 denier)! However, it is difficult to manufacture due to the inherent adhesion that occurs during spinning. The preferable range of single yarn fineness is 1.0 to 2.
5 denier 0 According to the present invention, the polyester σ terminal carboxyl group concentration must be 25 eq/IO'11 or less02
If it exceeds 5eq/10'jl, the moisture and heat resistance will fall below the level required for heavy-duty vehicle tires. If the terminal carboxyl group concentration becomes too small, the adhesion to rubber tends to decrease, so the preferable range for the terminal carboxyl group concentration is l! 1 is 10 to 20 eq/10. An example of the method for producing the polyester fiber of the present invention is shown below. Using a known melt spinning machine, a polyester chip coated with an active compound on the carboxyl group is melt spun through a spinneret having a large number of holes with a distance between the holes of 5 cm or more. At this time, the amount of polymer extrusion was set so that the fineness of the single filament after drawing was 0.8 to 3.0 deniers, and the
A heating gas of 0'C or more is supplied, and the range tube 40 am below the spinneret is maintained at a high temperature of 300C or more, so that the multilayer fold of the undrawn yarn becomes 3 x 10-'' or less. The undrawn yarn is continuously guided to a known drawing device, and 2
After being stretched 6.0 times or more in stages and then subjected to a relaxation heat treatment, it is made into a polyester fiber having a single filament thickness of 0.8 to 3.0 denier *yiii.

As the compound active on carboxyl groups, for example, monofunctional epoxy compounds, carbodiimide compounds, oxazoline compounds, etc. can be used.

The method for measuring physical properties in the present invention is as follows.

(1) Polyester proper term 1f Ortho-chloro e! as a solvent! Using phenol and varying the amount of polymer extrusion, 7splc was measured at 35°C,
The value extrapolated to the concentration O is taken as the intrinsic viscosity.

The working strength is measured under the following conditions using a known tensile tester.0 Yarn length: 250g&) Tensile speed: 30m/min Chart speed: 60m/min (S) The straw is placed under tension and subjected to steam treatment at 160°C for 2 hours.The strength of the straw after this steam treatment is used as a measure of moisture resistance.

(4) Fatigue resistance Gutdeyer's Cheve fatigue test method was used.

Tube shape: Inner diameter 12.7 ■ Outer IK 26.0 ■ Length 230 m Angle: 100° internal Pressure = 3. s/d Rotation speed: sso rpm A fatigue test was conducted for 6 hours under the above conditions, the cord was taken out from the tube, and the strength retention after the test was used as a measure of fatigue resistance.

(PoHL, H, A, method (Anal, (,'
hem.

26 (1954), 10. )K follow? 10”l?Mf)
f) The carboxyl group equivalent was measured. As shown in Table IK, polyester fibers obtained from the polyester fibers of the present invention have the same level of strength, heat and humidity resistance, and fatigue resistance as the cords for heavy vehicle tires currently manufactured from nylon fibers. For the first time, polyester fibers could be used as cords for heavy vehicle tires.

The polyester fiber of the present invention exhibits excellent performance as reinforcement for (1) rubber products other than Maku tires, and can be widely used, and is also excellent as an industrial fiber for ropes, fishing nets, and the like.

Table 1 Example 1゜[η] is 1.0. Terminal carboxyl group concentration 38 eq/
10' JI polyethylene terephthalate chips with Starbacsol I" (West Germany/Manufactured by Meninil) 1
．． Using a chip sprinkled with 0vt4, while maintaining the temperature between the lower part of the spinneret 401 at 300°C with a heating cylinder, the 0vt4 was spun from a spinneret with a hole distance of 8 m and a number of holes of 500, and the 0vt4 was dispersed at a speed of 300 m/min. Continuous drawing of undrawn yarn pipe 11
Then, the yarn was stretched 6.6 times in 1112 stages, and then limited shrinkage was performed 5 times at 230°C to obtain a drawn yarn of 1000 denier. The physical properties of the obtained drawn yarn were as follows.

(77): 0.96, terminal carboxyl group: 16e
q/IQ@艮Qiang[:10.211/d, Shin[:13ming,
Birefringence: 20s
The cord was twisted at a rate of 500 twists/m to obtain a raw cord.

Subsequently, an adhesive was applied to this raw cord, and then heat treatment was performed at 240° C. while applying a load of 0.1/d 2 using a heat treatment machine to obtain a treated cord. Obtained treatment MA: i-
D is a tire for heavy-duty vehicles as shown below;
12, Humid heat resistance: 934, Fatigue resistance: 984, Comparative example 1゜[η] is 0.76, 111 [27
A polyethylene terephthalate chip of eq/10'j coated with Metavaczol 1@64vt was spun from a spinneret with a hole distance of 11 holes and a number of holes of 192 while maintaining the temperature within 25 CII below the spinneret at 300°C using a heating tube. The yarn is spun at a speed of 300 m/min, and the undrawn yarn is continuously passed through a drawing process, where it is stretched 6 to 7 times in two stages, and then stretched at 230°C for three times. Perform storage10
It was wound up as a drawn yarn of 00 denier. The physical properties of the obtained drawn yarn were as follows.

(η): 0.72, group on terminal carboxy 7: 15 e
q/10"・Strong [: 9.15/d, elongation: 124, birefringence wheel: 201X10-" Next, the drawn yarn was twisted 500 times/twist using a twisting machine.
The raw cord was twisted at a twist rate of 500 times/m. After applying this green cord RC adhesive, heat treatment was performed at 240° C. using a heat treatment machine while applying a load of 0.1/d 2 to obtain a treated cord. The nine cords obtained had low strength and insufficient fatigue resistance as described below, and were unsuitable as I-ear cords for heavy-duty vehicles.

Strength: 6.3jl/d, tension: 17'lG, 1tst heat resistance = 96g, fatigue resistance = 87 The yarn was set as shown and drawn to obtain a drawn yarn of 100 G denier. Table 2 shows the physical properties of cords obtained by treating these drawn yarns in the same manner as in Example 1.

As is clear from the results in Table 2 below, the birefringence is 200
A cord obtained from fibers of 10-" or more has a strength of 9, making it suitable for high-weight applications. i Obtained drawn yarns with different single yarn weave changes. The physical properties of the obtained drawn yarns and the physical properties of the cord obtained by passing these drawn yarns in exactly the same manner as in Example 1 are shown in ms.
As is clear from the results in Margin Table 3.0 below, the cord that satisfies the requirements of the present invention with a single thread W of 3 deniers or less has excellent strength, heat and humidity resistance, and fatigue resistance.
It would be suitable for use in heavy-duty vehicles.@Example 4゜In Example 1, the amount of terminal blocking agent added was varied to obtain drawn yarns with carboxyl group amounts as shown in Table 4◇This drawn yarn Table 4 shows the physical properties of the cord obtained by @NI in the same manner as in Example 1.

As is clear from the results in Table 4 below, cords obtained from fibers with a syl group content of 28@q/1G@# or less in the terminal strength report have excellent temperature and heat resistance for use in heavy-duty vehicles. -ta0

[Brief explanation of the drawing]

1811th? ! Schematic graph showing the effect of the wire arrangement on the strong fK of the twisted yarn 1II''es (when the number of lower twists and the number of upper twists are the same) 0 Asahi Kasei Corporation Application agent Patent Attorney: Akira Makoto, Patent Attorney: Kumo Nishidate, Patent Attorney: Ishi 1) Honorable Patent Attorney: Akira Yamaguchi

Claims (1)

[Claims] It consists of a polyester in which 1.95-1004 moles are ethylene terephthalate units and the remaining 1 to 0 moles are other ester units, and the polyester has an intrinsic viscosity of 0.
80 to 1.20, the multilayer folded book is 200XIF" or more, the single yarn fineness is 0.8 to 3 denier, and the terminal carboxyl group concentration of the polyester is 23eq/10@jl or less. Performance polyester fiber 0