JPH03161508A - Polyester fiber for rubber reinforcement and production thereof - Google Patents

Abstract

PURPOSE:To obtain the title polyester fiber containing a carboxyl terminal group and diethylene glycol at a specific ratio, having specific intrinsic viscosity and strong elongation product, good dimensional stability and high toughness and capable of providing excellent uniformity and endurance to tire. CONSTITUTION:The aimed polyester fiber containing (A) <= 25 eq/ton carboxyl terminal group (COOH) and (B) <=1.3wt.% diethylene glycol(DEG) and preferably obtained by using (C) 30-150ppm antimony compound and 5-120ppm germanium compound as a polymerization catalyst and being >=0.85 in intrinsic viscosity(IV), <8% in middle elongation + dry heat shrinkage (S), >=2S+11 in strong elonga tion product (TE<1/2>) and <=40g/d in terminal modulus(TM).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to polyester fibers for rubber reinforcement. More specifically, the present invention relates to polyester fibers for reinforcing rubber, which have good dimensional stability, high toughness, and good durability, and can produce tires with good uniformity and durability.

[Prior Art] Polyester fibers have excellent mechanical properties, dimensional stability, and durability, and are widely used not only for clothing but also for industrial applications. Among these, it is used in large quantities for reinforcing rubber materials such as tire cords, taking advantage of its characteristics. Conventionally, for tire cord applications, high-strength raw yarns have been used by drawing low-oriented undrawn yarns at high ratios, but in recent years, relatively highly oriented undrawn yarns (so-called POY) have been drawn. Raw yarn is now used. This improves the dimensional stability of the cord and improves tire performance, even at the cost of some strength.
This is a technique that was born out of the desire to make people feel angry.

[Problem to be solved by the invention] Especially in recent years, as tire cords for passenger cars, 1.
- There is a growing trend to use polyester fibers in areas where yarn is used, and polyester fibers are also required to have unprecedented dimensional stability. In response to such demands, techniques have been disclosed to increase the spinning speed of undrawn yarn (POY) and improve its dimensional stability, as proposed in JP-A-61-165547 and JP-A-6119812. ,ing. While I was playing,
As an extension of the conventional technology, can t-method stability be improved simply by increasing the spinning speed of POY? As the spinning speed of POY increases, the toughness decreases significantly, and as a result, the durability of the tire cord, especially the fatigue resistance, decreases significantly. The reality is that it is not.

The inventors of the present invention have considered this problem, and as a result of intensive research on tire cords that have good dimensional stability, toughness, and durability and can be used as a substitute for 1-no-yon, the inventors have fundamentally designed the voluminous material. By controlling certain particles and controlling and improving the orientation characteristics during spinning from the viewpoint of the polymer properties, polyester can be produced! The physical properties of a fibers were determined by rM. Dense:
<<;(・t, box 0, = 27 nl one roll '-' - for the first time') I found out that I can give three commands for one purpose.

That is, the purpose of the present invention is {1} carboxyl terminal group retirement ([COO}{]
) is 25 eg/ton or less, diethylene green
・The alcohol content (DEG) is 1.3 wt% or more”4
Intrinsic viscosity (IV)≧0■85 Intermediate elongation Ten-dry heat shrinkage (S)<8% Strong elongation product (T,/'?)≧2 5 + ]. ．．
] Terminal modulus (TM)≦40g/ci
Refers to Bori-oh Stell whose main repeating unit is 1-.

As a polyester, in order to improve dimensional stability and strength, by-product diethylene glycono1. It is preferable that polyethylene terephthalate is substantially free of addition of the third precept, copolymerization, or inorganic particles.

The polyester fiber of the present invention exhibits no dimensional stability and must have an intermediate dry heat shrinkage, ie, dimensional stability (8) of less than 8%. If the amount of 8 is more than 8%, a polyester cord with low shrinkage and high modulus cannot be obtained, and it is impossible to substitute for rayon. From this point of view, S is preferably 7.5% or less.

The toughness (T, r7> of the polyester fiber of the present invention is T
It must be a high toughness fiber that satisfies F1≧23+11. In general, when highly oriented spinning is carried out to reduce the dimensional stability (S), the toughness (T./''T) also decreases markedly. However, the fatigue resistance of the tire cord ε is the same. In terms of toughness, 8 tends to be better.As a result of research by the present inventors, the limit of toughness that satisfies the durability of a tire becomes lower as dimensional stability (S) decreases; It was found that with two hearts with low stability (S), even with relatively low toughness, the durability reaches a level where you can wear 4 pairs of shoes.
With Ichino. Intensive study on the lower limit of such toughness 1,
As a result, by setting TJ7: ≧28+11, I/-
They found that sufficient durability (fatigue resistance) can be achieved if S is in a small range, which is the type of yarn that is aimed at replacing Yong. More preferable results are obtained.

In addition, the carboxyl terminal group i (COOH) of the polyester fiber of the present invention must be 2 5 eg/ton or less. If [COOH] exceeds 258 Mton, the heat resistance in the rubber deteriorates, resulting in insufficient durability as a tire cord. [COOH] is preferably 2 1 eg/ton or less.

Furthermore, the amount of diethylene glycol (DEG>) in the polyester fiber of the present invention needs to be 1.3 wt% or less.

When DEC exceeds 1.3wt%, dimensional stability deteriorates,
Moreover, durability becomes poor. From this point of view, DEG is 1.
It is preferably 1 wt% or less, and more preferably <0.9 wt% or less.

The intrinsic viscosity (IV) of the polyester fiber of the present invention is 0.8
Must be 5 or more. If IV is less than 0.85, durability is insufficient no matter what conditions are adopted. From this point of view, IV is preferably 0.9 to 1.3.

Furthermore, the terminal modulus of the polyester fiber of the present invention must be 40 g/d or less. If the terminal modulus exceeds 40 g/d, no matter how tough the yarn is obtained, the strength will decrease during twisting, and the toughness as a tire cord will decrease, resulting in poor durability. From this point of view, the terminal modulus is preferably 30 g/d or less.

The high toughness polyester fiber satisfying <Tfl≧23+11 as in the present invention cannot be obtained simply by the conventionally known high-speed spinning and drawing method.

As a result of intensive study on measures to improve toughness in a region with low dimensional stability (S) as in the present invention, we found that it is important to strictly control the oriented crystallization behavior in oriented crystallization such as high-speed spinning. I found out something.

Conventionally, structural control of such POY has mainly focused on controlling cooling conditions, but as a result of more detailed research, it has been found that by strictly controlling the catalyst composition during the production of the polymer, the particles in the polymer can be significantly reduced. It was also found that modification from the polymer aspect, which involves controlling the conformation and crystallinity of POY by selecting a catalyst, is effective. We have found that a combination system of antimony compounds and germanium compounds is effective as such a catalyst composition, since it does not fall down when used as a conventional rubber reinforcing material. That is, 30 to 150 ppm antimony compound as antimony and 5 to 120 ppm as germanium.
It has been found that the use of a germanium compound as a polymerization catalyst is effective in achieving the object of the present invention.

The antimony compound is preferably antimony trioxide or antimony pentoxide, and the germanium compound is preferably germanium dioxide.

If the amount of antimony compound is less than 30 ppm, a large amount of germanium compound must be used in combination in order to maintain polymerization reactivity, which not only increases cost, but also increases the cost.
The amount of diethylene glycol increases and the dimensional stability decreases. If the amount of antimony compound exceeds 150 ppm, even if the amount of germanium compound used in combination is increased, the reduction of antimony metal will not be achieved due to the reduction of the antimony compound, and the strength and toughness of the yarn will not be improved, and the rubber will deteriorate. The heat resistance inside also decreases. Furthermore, if the amount of germanium compound is less than 5 ppm, the amount of antimony compound used cannot be reduced to 150 ppm or less in order to maintain polycondensation reactivity. Moreover, if the amount of germanium compound exceeds 120 ppm, the cost will increase significantly and it will not only be impossible to use industrially, but also DEGi will be high and dimensional stability will deteriorate. From the viewpoint of anti-corrosion, the amount of the antimony compound is preferably 40 to 120 ppm as antimony, and 80 to 120 ppm.
m is more preferred. Further, the amount of the germanium compound is preferably 6 to 30 ppm as germanium.

As mentioned above, controlling the catalyst composition of the bolymer to reduce defects in the yarn is effective in improving toughness and durability, but such improvement is particularly achieved by reducing the amount of antimony metal precipitated by reducing the antimony compound. It is valid. That is, the effect of the present invention is further enhanced by controlling the amount of antimony metal in the fiber to 5 ppm or less, more preferably 3 ppm or less.

A method for industrially obtaining the polyester fiber of the present invention will be described below.

A polycondensation reaction is carried out using an antimony compound of 30 to 1 to 50 ppm as antimony and a germanium compound of 5 = 120 ppm as germanium as polymerization catalysts. In this case, it is preferable to use phosphoric acid as the phosphorus compound and to add phosphoric acid at the beginning of polycondensation and before addition of germanium compounds such as antimony compounds.
The conditions of charging amount, polymerization temperature, and polymerization time are selected appropriately, and IV0.65 or more, COOH≦25eg, "to
n, DE G≦1−, 3 W t% boriethylene 1
/nterephthalate chips were obtained.

The chips thus obtained were subjected to solid-phase polymerization, if desired, according to a conventional method to obtain polyethylene terephthalate of IV], , 0 or higher.

The chips obtained in this way are melt-spun according to the usual method, slowly cooled in a heating cylinder, and then cooled and solidified in a chimney wind before being collected. At this time, the piping and back parts in the spinning machine are plated with chrome-plated,
It is preferable to suppress the precipitation (reduction) of antimony metal.Also, as a filter for passing through males, it is absolutely
)t. It is preferable to use the following metal wire (SUS) nonwoven fabric. Furthermore, it is more preferable to reduce the amount of dust in the nitrogen used in the solid-phase polymer and the nitrogen in the spinning machine as much as possible, and to reduce the amount of dust by passing through the air using a chimney style. . The number of foreign substances present in the yarn is reduced to 800 pieces/■ or less, more preferably l
In order to improve toughness and Δ resistance, it is a preferable method to maintain the level of ~500 particles/■ or less.

Thus, the yarn is discharged from the nozzle and the degree of orientation (Δn) is 8.
0X10-3 or more, preferably (△n) is 95X10
' Highly oriented spinning so that the (Δn) is sox
If POY of less than io-3 is used, the dimensional stability will be poor. This undrawn yarn (POY) is spun and subsequently or once rolled, then hot roller stretched and heat-set at a temperature of 210°C or higher.21. Dimensionally stable when heat-set at a temperature of less than 0°C. In this case, it is preferable to set the draw ratio to 0.93 times or less than the break draw ratio of the undrawn yarn because the terminal modulus can be reduced and defects such as voids in the fiber can be suppressed.

Although the polyester fiber of the present invention can be obtained by the following method, it is important to suppress the oriented crystallization resistance of POY in order to improve the dimensional stability and increase the toughness. As a result of research on effective volima compositions for such control, it was found that the scale, amount, addition method, etc. of the phosphorus compound are important factors.

Phosphorus compounds are generally used to improve the durability of volima, but it is a truly surprising fact that phosphorus compounds affect the dimensional stability of fibers in relation to their toughness, as described above, and the present inventors This is a new finding discovered as a result of their research.

As a result of the research conducted by the present inventors, phosphoric acid was used as the phosphorus compound, the amount applied was 10 to 40 ppm as phosphorus, and the timing of addition was at the beginning of MW1. Two is better [2
I discovered something. By using such a phosphorus compound, the toughness of the fiber can be increased for the same dimensional stability.

That is, TFR≧23+14.0 can be achieved. It is unclear why such phosphorus compounds exert their effects.
1. The present inventors assume that the formation of the fiber structure during spinning is controlled by the thickening effect of phosphoric acid by appropriately adding a trifunctional phosphorus compound such as phosphoric acid at the initial stage of polymerization.

[Example] The present invention will be explained in more detail with reference to Examples below.

Note that the physical properties in the examples were measured as follows.

A. Metal stars (antimony-5-germanium, phosphorus content, etc.) in the volima and fibers were determined using the fluorescent X-ray method.

B7 carboxyl terminal group amount ([COOH]) sample 0
．． Dissolve 5' in 10 owl of 0-chloride/sol, and after completely dissolving, cool and add 3 ml of chloroform.
It was determined by potentiometric titration using a methanol solution of OH.

C. After a sample of DEG was subjected to alkaline decomposition, it was determined using gas chromatography. D. Tensile strength, intermediate elongation, terminal modulus using a Tensilon tensile tester manufactured by Toyo Baldwin Co., Ltd., with a test length of 25.
The strength and elongation were calculated by obtaining the SS curve at a drawing speed of 30 cm/min.

Further, from the same SS curve, the elongation corresponding to the strength of 4.5 g/d was read to determine the intermediate elongation.

The terminal modulus was determined by dividing the difference between the stress at the point where 2.4% was subtracted from the cutting elongation and the breaking stress by 2.4×10 −2 .

E. Dry heat shrinkage rate ΔSd Take a sample in the form of a skein and place it in a temperature-controlled room at 20°C and 65% RH for 24 hours.
After being left for more than an hour, a sample of length no., which was measured by applying a load equivalent to 0.1 g/d of the sample, was left in an oven at 150°C for 5 minutes without tension, and then removed from the oven and described above. It was left in a temperature-controlled room for 4 hours, and the above load was applied again, and the measured length a1 was calculated using the following formula.

ΔSd= (Q o −U 1＞/no xlOO
(%〉F. Number of foreign objects in the thread) The sample was divided into individual threads and the thread was stretched on a slide glass so that it did not slacken.
Using an Olympus optical microscope (phase contrast method), magnification 20
Scan at 0x magnification and count the number of foreign objects in the thread. Perform the measurement with N number 5, find the average value X (ke/6ω), and convert this value to the number of foreign substances per ■.
0.8 g of the sample is dissolved in 10 ml of the solution (referred to as p), and the relative viscosity (ηr) is determined using the following formula using an Ostwald viscometer, and I■ is also calculated.

ηr=η/ηo=tXd/toXdo I V=0.024277 r +0.2634η:
Viscosity of Bolima solution η0: Viscosity of solvent t: Falling time of solution (seconds) d: Density of solution (g/cd) to: Falling time of OcP (seconds) do: Density of OcP (g/cJ) H. Antimony Metal content Volima 40g was mixed with orthochlorophenol (QC P >
Dissolve in 500011 and centrifuge (l2.○OOr
pmX2 hours), then washed and dried. The spectrum of the obtained centrifuged grains is measured using an X-ray diffraction device, and metal antimony is determined from the spectrum.

■． A heat-resistant cord in rubber was embedded in rubber, and the strength retention rate after vulcanization at 150°C for 6 hours was evaluated. Strong retention rate of 60% or more ◎, 5
0% or more and less than 60% was rated O, and less than 50% was rated x.

J. Fatigue resistance (GY life) Tube internal pressure 3.5 kg/according to ASTM-D885
The bursting time of the tube was determined at oJ, rotational speed of 850 rpm, and tube angle of 90°. The evaluation is based on conventional tire cord (manufactured by Toray Industries, Inc. 100 0-24 0-70
3M) 1-30% increase ◎, same level as conventional tire cord
An increase in the labor cost is marked as ○, and an inferior result is marked as an X.

Example 1 100 parts of dimethyl terephthalate and 5 parts of ethylene glycol
Add 0.035 parts of manganese acetate tetrahydrate to 0.2 parts,
Transesterification was carried out using a conventional method. Next, 0.0091 part of phosphoric acid (29 p as phosphorus) was added to the obtained raw material.
pm), then add 0.0025 parts of germanium dioxide (
17 ppm as germanium), and further added 0.0125 parts of antimony trioxide (104 parts as antimony).
pm) and a polycondensation reaction was carried out for 3 hours and 10 minutes. (Polymerization temperature: 285°C) The intrinsic viscosity (IV) of the obtained bolamer was 0.72, and the amount of carboxyl terminal groups ([COOH]
) is 17. leg/ton, DEG amount is 0.7wt%
Met.

The amount of antimony in the Borima is 1. The amount of germanium was 10 ppm, and the amount of phosphorus was 20 m)pm.

Furthermore, the amount of antimony metal in Borima was 0.3 ppm. The above-mentioned volima was pre-dried at 160° C. for 5 hours and then homopolymerized at 225° C., IV=1. Thirty-five solid phase polymerized chips were obtained. This chip is spun using an extruder type spinning machine at a temperature of 2
Spinning was carried out at 95°C.

At this time, a metal nonwoven fabric with an absolute elapsed time of 1 to 5 μm was used as the filter, and a round hole with a diameter of 0.6 mm was used as the cap. In addition, chromium plating was applied to the parts of the bollima piping and back parts that come in contact with the bollima, and the nitrogen in the bopper and the nitrogen for the chimney were all passed through a 1μ filter before use. The thread discharged from the nozzle has a length of 25 mm and an inner diameter of 25-φ.
After being slowly cooled in a heating cylinder at a temperature of 300° C., the specimens were cooled and solidified by applying chimney cooling air, and after oiling, they were taken at the taking-up speed shown in Table 1. The resulting unstretched system was stretched at a stretching temperature of 90°C and a heat treatment temperature of 240°C, with the magnification and relaxation ratio changed to obtain a stretched system.
The stretching ratio is 0.88 to 0.92 which is the limit ratio for NQ1 to 3.
NQ4 was set to 0.95 times the limit magnification. The number of foreign substances in the polyester fiber yarn produced in this way was 15.
0 cases/■ to -450 cases/■, and IV 0.98 to 1.

01, the amount of carboxyl terminal group is 1 4e (1/toll
, DEG was 0.7 wt%. Next, this drawn yarn was first twisted at 49T/1 0cm in the S direction, and final twisted at 49T/10an in the Z direction to form a raw cord.

Next, a treated cord was prepared by dipping this cord in adhesive using a two-bath method using a combination treater manufactured by Riller. Table 1 shows the physical properties of the yarn and treated cord.

(Left below) As is clear from Table ■, Δ1l of undrawn yarn is 80XIO
When the Na 1 was less than -3, the dimensional stability exceeded 8%, and the tire performance (possibility of replacing rayon) was at an unsatisfactory level. Also, under the same conditions as NQ2, the stretching ratio was set to 0, which is the limit stretching ratio.
．． The terminal modulus of N (14), which was made higher than 93 times, exceeded 40 g/d. Therefore, although the strength of the yarn was high, the strength retention rate was poor, and the strength of the dip cord was low, resulting in unsatisfactory fatigue resistance.POY Δn of 80X10
-3 or more, dimensional stability less than 8%, strong median product T/-
≧2 S +1. ]−, the terminal modulus is 40
No. g/d or less. 2 and 3 are tire performance, fatigue resistance,
A cord with good heat resistance was obtained.Example 2 A drawn yarn and treated cord were obtained under the same conditions as Nα2 in Example 1, except that the amount of polymerization catalyst used was changed as shown in Table 2. The results of drawn yarn properties are shown in Table 2, and the results of treatment codes are shown in Table 3.

As is clear from Tables 2 and 3, sb is 30 to 150
ppm antimony compound, 5-120pp as Ge
NQ2, 6, 7 using m germanium compound are C
The O O H and DEG amounts were both good, and the resulting fibers also satisfied Tfl≧23+11 and had good heat resistance and fatigue resistance in rubber.

However, in Nα5 and Nα11 using an antimony compound exceeding 150 ppm as sb, the sb metal increases and the toughness of the fiber is low, and the strength elongation product TFτ≧2S+11 is not satisfied. These Nα5 and N(111) had inferior fatigue resistance compared to conventional products.
Nα8 using an antimony compound of less than
It exceeded a ton. Therefore, the aging resistance in rubber was poor.

Further, in Nα9, in which less than 30 ppm of an antimony compound was used as sb and Ge was increased from 120 ppm as a germanium compound, the DEG expression exceeded 1.3 Wt%.

Therefore, the dimensional stability (S) increases, and T(Mo≧23
+1 Neither requirement 1 was met. In N(19), both the fatigue resistance and the heat resistance in the rubber decreased. In addition, NQ 10 with a germanium compound amount of less than 5 Dpm as Ge had poor polymerization reactivity, and the (Coo days) in the yarn exceeded 25 eMton, resulting in poor heat resistance. was insufficient.

Example 3 A drawn yarn was cut using the same wire as in Example 1, No. 3, except that the same number of moles of trimethyl phosphate was used as the phosphorus compound used during polymerization. Table 4 shows the characteristics of each drawn yarn.

Table 4 Simply changing the phosphorus species from phosphoric acid to phosphoric acid l-rimethinolate deteriorated the dimensional stability of the fiber by 0.8% [7L].

For this reason, the dimensional stability is similar to that of J, but the toughness is inferior. That is, ζ' using phosphoric acid and dimethyl does not satisfy rJU'≧23-}11.

Although the fatigue resistance of N012 is a better level than the conventional product, it is inferior to NQ3, and the difference from the conventional product is small.

[Effects of the Invention] The polyester fiber of the present invention has significantly better dimensional stability and toughness than conventional products. Polyester fibers have a low shrinkage rate when used as a tire tire, and can be used as a substitute for tire tires, as well as simplifying the post cure inflation (PCI) process, which is commonly used in the tire manufacturing process. .

1 - ``Applicant: Toray Industries, Inc.''

Claims (3)

[Claims] (1) Carboxyl terminal group amount ([COOH]) is 25e
g/ton or less, diethylene glycol content (DEG
) is 1.3 wt% or less, and the intrinsic viscosity (IV) is ≧0.
85 Polyester fiber for rubber reinforcement having intermediate elongation + dry heat shrinkage (S) <8% strong elongation product (T√E) ≧2S+11 terminal modulus (TM) ≦40 g/d. (2) The polyester fiber for rubber reinforcement according to claim (1), comprising a polyester using as a polymerization catalyst 30 to 150 ppm of an antimony compound as antimony and 5 to 120 ppm of a germanium compound as germanium. (3) Polyester obtained using 30 to 150 ppm of antimony compound as antimony and 5 to 120 ppm of germanium compound as germanium is highly oriented and spun to obtain an intrinsic viscosity of 0.9 or more and degree of orientation (Δn) of 80 x 10^- A method for producing polyester fibers for rubber reinforcement, which is characterized in that the fibers are highly oriented with an orientation of ^3 or more, then stretched at a stretching ratio of 0.93 times or less than the limit stretching ratio, and heat set at a temperature of 210° C. or higher.