JP2770509B2 - Polyester dip cord - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyester dip cord. More specifically, the present invention relates to a polyester dip cord which is excellent in strength and durability when used as a tire cord and can greatly reduce the amount of cord used in a tire.

[Conventional technology]

Polyester fibers are widely used not only for clothing but also for industrial applications because of their excellent mechanical properties, dimensional stability, and durability. Particularly in tire cord applications, the use amount has been increasing in recent years due to its excellent performance.

Conventionally, in high-strength yarns, high-strength yarns obtained by stretching low-oriented undrawn yarns at a high magnification have been used.However, since such high-strength yarns have a high heat-sensitive shrinkage, they are embedded in rubber as tire cords and used in tires. When molded, there is a problem that the uniformity of the tire is deteriorated due to contraction of the cord.
In order to solve such a problem, it has been proposed to improve dimensional stability as a tire cord by stretching a relatively highly oriented undrawn yarn (so-called POY) to have a high strength. It has become the mainstream of technology.

[Problems to be solved by the invention]

As described above, in the related art, the degree of orientation of an undrawn yarn to be drawn to improve the dimensional stability of a tire cord is increased. For example, Japanese Patent Application Laid-Open No. 57-154410 discloses such a prior art. However, the relationship between the dimensional stability (intermediate elongation + dry heat shrinkage) and the cord strength of the processing code (dip cord) of the embodiment described in this publication is as shown in FIG. There is a problem that the cord strength is reduced if the property is improved. Further, in the prior art, when the orientation of undrawn yarn is increased to improve dimensional stability, not only the strength of the tire cord is reduced but also the heat resistance in rubber is significantly deteriorated. ing.

On the other hand, in recent years, there has been a growing demand from tire manufacturers for the development of a dip cord capable of reducing the amount of cord used per tire while improving the uniformity (roundness) of the tire. For this purpose, dimensional stability is good and strength,
Although a highly durable polyester dip cord is required, the above-mentioned conventional technology cannot cope with the strength and durability of the dip cord at present.

An object of the present invention is to provide a dip cord capable of reducing the amount of cord used for a tire by 20% or more by solving the above-mentioned problems and improving strength and durability while improving dimensional stability. Is to do.

[Means for solving the problem]

The object of the present invention described above is to use 150p as antimony metal.
pm or less antimony compound, 5 as germanium metal
It can be achieved by a polyester dip cord containing up to 60 ppm of a germanium compound and having the following physical properties.

A. [Intermediate elongation + dry heat shrinkage] (S) (%) 7 ≦ S ≦ 9 B. Cord strength T (g / d) T ≧ 0.27S + 4.57 C. Intrinsic viscosity (IV) IV ≧ 0.85 D .Amount of carboxy terminal group [(COOH)] (eq / ton) (COOH) ≦ 25 In the present invention, the polyester means a polyester containing ethylene terephthalate as a main repeating unit.

Further, in the present invention, the polyester dip cord is a cord in which a cord is dipped into a commonly used adhesive to enhance the adhesiveness to rubber, and the adhesive is applied to the surface thereof.

In the present invention, [medium elongation + dry heat shrinkage] (S), which indicates dimensional stability of the polyester dip cord, is 7 to 9
Must be%. If this S exceeds 9%, it becomes difficult to manufacture a uniform tire having high roundness due to lack of dimensional stability. Further, if S is less than 7%, the current manufacturing technology in the industry does not provide sufficient durability and strength to significantly reduce the cord usage by 20% or more.

Further, the strength (T) that the polyester dip cord of the present invention should have is required to satisfy T ≧ 0.27S + 4.57 (g / d) in relation to the dimensional stability (S). When the strength T satisfies the above formula, the fatigue resistance of the polyester dip cord can be improved. In other words, it is possible to significantly reduce the cord usage by 20% or more while maintaining the same fatigue resistance as the conventional one.
From such a viewpoint, the strength T of the dip code is more preferably set to satisfy T ≧ 0.27S + 5 (g / d).

In the present invention, the polyester dip cord having the above-described properties needs to have an intrinsic viscosity (IV) of 0.85 or more. If the intrinsic viscosity is less than 0.85, it is not possible to obtain the fatigue resistance that reduces the cord usage by 20% or more.
More preferably, the intrinsic viscosity is 0.95 or more. However, in order to suppress heat generation in the tire, it is not desirable that the intrinsic viscosity is too high.

Further, the amount of carboxy terminal groups (COOH) of the polyester dip code of the present invention needs to be 25 e / ton or less. If the COOH amount exceeds 25 eq / ton, the heat resistance in the rubber becomes insufficient, and it becomes difficult to reduce the cord usage by 20% or more. More preferably, the amount of COOH is set to 20 ep / ton or less.

Further, the amount of the antimony compound contained in the polyester dip cord of the present invention is 150 p as an antimony metal.
It must be less than pm. The antimony compound is used as a polymerization catalyst for the polyester.
If more than pm remain, the heat resistance of the cord in the rubber of the tire deteriorates. Therefore, the amount of the antimony compound in the dip code needs to be 150 ppm or less as antimony metal, preferably 120 ppm or less, more preferably 50 to 120 ppm.

Further, the polyester dip cord of the present invention needs to contain 5 to 60 ppm of a germanium compound as a germanium metal. 5ppm as germanium metal content
With a germanium compound content of less than 150 ppm or less of the antimony compound as an antimony metal, the amount of COOH of the polymer cannot be reduced by the ordinary polymerization method in the catalyst system, and therefore the COOH of the dip code should be 25 eq / ton or less Is difficult. This is when the content of antimony compound is 150 ppm or less as antimony metal,
This is because the polymerization reactivity decreases. If the amount of the germanium compound exceeds 60 ppm as germanium metal, the heat resistance of the cord in rubber becomes insufficient, and it becomes difficult to reduce the cord usage by 20% or more. More preferably,
The content of the germanium compound is preferably 7 to 20 ppm as germanium metal.

As described above, antimony trioxide or antimony pentoxide is preferable as the antimony compound used in the dip code, and germanium dioxide is preferable as the germanium compound.

As described above, the content of the antimony compound is reduced,
By assisting the reduction with a germanium compound, the heat resistance (IRT) of the cord in rubber is improved.
Specifically, in relation to the dimensional stability S, IRT ≧ 8.57S + 8 (%), and more preferably, IRT ≧ 8.57S + 10 (%), and it is possible to significantly improve tire performance (durability). In the present invention, the use of a germanium compound to compensate for the decrease in antimony compounds, and not using other polymerization catalysts such as titanium compounds and tin compounds,
This is because these polymerization catalysts generate a large number of particles in the polymer and cannot obtain a high-strength dip code.

The polyester dip cord of the present invention described above can be obtained, for example, by the following manufacturing method. A polycondensation reaction is performed by adding an antimony compound as a polymerization catalyst so that the remaining amount as antimony metal in the polymer is 150 ppm or less, and the remaining amount as a germanium metal in the polymer is 5 to 60 ppm, and a COOH amount is obtained. 27eq / t
on or less, preferably diethylene glycol (DEG)
Polyester with an amount of 1.3 wt% or less is produced. The thus obtained polyester is subjected to solid-state polymerization to obtain a raw material having an intrinsic viscosity of IV 0.9 or more. The raw material is melt-spun according to a conventional method, and the yarn discharged from the spinneret is passed through a heating tube, gradually cooled, then cooled and solidified by a chimney style, and taken up at a take-up speed of 1500 to 3000 m / min. At this time, control the residence time and spinning temperature during spinning,
A yarn with a COOH content of 25 eq / ton or less is obtained. Subsequently, or after being wound once, it is drawn and heat-treated according to a conventional method to obtain a drawn polyester yarn. At this time, when the stretching ratio and the relaxation rate during the heat treatment are selected and the terminal modulus is set to 50 g / d or less, a decrease in the strength at the time of subsequent twisting can be suppressed. Also,
The heat treatment temperature at this time is preferably 200 ° C. or higher.

The drawn yarn thus obtained is twisted 30 to 60 times per 10 cm (upper twist) according to a conventional method, and then a plurality of plied yarns are twisted 30 to 60 times per 10 cm (primary twist) in the opposite direction. Produce raw cord. Next, the raw cord is treated with an adhesive according to a conventional method to obtain a dip cord. At this time, it is preferable that the temperature of the heat treatment zone is 240 ° C. or more and the stretch ratio is 5 to 10%, and the temperature of the relaxation zone is 240 ° C. or more and the relax ratio is 3% or more.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to examples. The physical properties in the examples were measured as follows.

(1) Metal content (antimony and germanium content) in the dip code was determined by a fluorescent X-ray method.

(2) COOH Amount 0.5 g of a sample was dissolved in 10 ml of o-cresol, the adhesive was removed by filtration, and after cooling, 3 ml of chloroform was added and potentiometric titration was performed with a methanol solution of NaOH.

(3) DEG amount After the sample was alkali-decomposed, it was quantified using gas chromatography.

(4) Intrinsic viscosity (IV) Orthochlorophenol using an Ostwald viscometer
After dissolving 8 g of the sample in 100 ml, the relative viscosity η _r of the solution from which the adhesive component was removed by filtration was measured at 25 ° C., and the intrinsic viscosity IV was calculated by the following approximate expression.

IV = 0.0242η _r +0.2634 t: Fall time of solution (second) to: Fall time of orthochlorophenol (second) d: Density of solution (g / cc) do: Density of orthochlorophenol (g / cc) (5) Dry heat shrinkage sample taken up in skein-like, 20 ° C., then was allowed to stand for 24 hours or more temperature control chamber 65% RH, the sample length l ₀ which is measured by applying a load corresponding to 0.1 g / d of the sample, no tension state And left in an oven at 177 ° C. for 30 minutes, taken out of the oven, left in the temperature control room for 4 hours, and again calculated from the length l ₁ measured by applying the above load.

Dry heat shrinkage = [(l ₀ −l ₁ ) / l ₀ ] × 100 (%) (6) Strong elongation, intermediate elongation Using a Tensilon tensile tester manufactured by Toyo Baldwin Co., Ltd., test length 25 cm, take-off speed An SS curve was obtained at 30 cm / min, and the elongation was calculated.

The intermediate elongation was the elongation at a stress of 4.5 g / d for the original yarn and the elongation at a stress of 2.25 g / d for the treated cord.

(7) Heat resistance in rubber (IRT) A dip cord was embedded in rubber and evaluated by the strong retention after vulcanization at 150 ° C for 6 hours.

(8) Fatigue resistance (GY life) According to ASTM-D885, the rupture time of the tube was determined at a tube internal pressure of 3.5 kg / cm ² , a rotation speed of 80 rpm, and a tube angle of 90 °. The result is a commercially available tire cord (Toray Co., Ltd. 10
00-420-703M) as the reference code,
○, ×.

◎: Level up 30% or more of reference code ○: Level up 20% or more to less than 30% of reference code ×: Level less than 20% increase of reference code Example 1 100 parts of dimethyl terephthalate and ethylene glue Call 50.
0.035 parts of manganese acetate tetrahydrate was added to 2 parts, and transesterification was carried out by a conventional method. Phosphoric acid in the resulting product
After addition of 0.0091 parts, 0.0025 parts of germanium dioxide and 0.0125 parts of antimony trioxide were added.
The polycondensation reaction was performed for 50 minutes.

The intrinsic viscosity of the obtained polymer is 0.715, COOH amount 18.9eq / to
n, DEG amount was 0.9 wt%. The amount of antimony in the polymer was 100 ppm, the amount of germanium was 14 ppm, and the amount of phosphorus was 22 ppm.

After preliminarily drying the polymer at 160 ° C. for 5 hours, it was subjected to solid-phase polymerization at 225 ° C. to obtain a solid-phase polymerization chip having an intrinsic viscosity IV shown in Table 1. The chips were spun with an extruder-type spinning machine at different spinning temperatures and residence times to obtain yarns with different COOH.
In spinning, the spun yarn discharged from the nozzle of the discharge hole with a diameter of 0.66 mm is gradually cooled in a heating cylinder with a length of 250 mm and a temperature of 300 ° C, then cooled and solidified by applying 18 ° C air cooling, and the take-off shown in Table 1 is taken. Picked up at speed.

The undrawn yarn thus obtained is drawn at a temperature of 90 ° C.
At a heat treatment temperature of 240 ° C., the draw ratio and the relaxation rule were changed to obtain a drawn yarn as shown in Table 1. Next, this drawn yarn was made into a raw cord by applying a lower twist of 49 T / 10 cm in the S direction and a upper twist of 49 T / 10 cm in the Z direction. Next, the raw cord was dipped with an adhesive using a Ritzler computer to prepare a processing cord. The processing conditions were a fixed length treatment at 160 ° C. in the drying section, a tension treatment at 240 ° C. in the heat treatment section, and a relaxation treatment at 240 ° C. in the post-treatment section. The intermediate elongation of the treated cord was adjusted to 3 to 4% by adjusting the tension and relaxation rates. The intrinsic viscosity IV, the amount of COOH and the physical properties, and the heat resistance and fatigue resistance of each of the treated cords are as shown in Table 1.

As shown in Table 1, No. 1 having (intermediate elongation + dry heat shrinkage) (S) of more than 9% has insufficient tire uniformity. In addition, No. 6 in which S is less than 7% has a low strength (T) of the treated cord and does not satisfy T ≧ 0.27S + 4.75, and its fatigue resistance is not much different from the conventional one. Heat resistance in rubber (IRT) was also low. In Nos. 8 and 7 obtained by increasing the draw ratio of the same undrawn yarns as Nos. 3 and 4, the strength of the original yarn was high, but the strength of the twisted yarn was greatly reduced, and the strength of the dip cord was reduced. As a result, in No. 8, T ≧ 0.27S + 4.75 was not satisfied, and the fatigue resistance was at a level not much different from the conventional product (reference code). Also, although No. 7 had an improvement effect as compared with No. 4 as compared with the reference cord, the improvement in fatigue resistance was smaller. In addition, intrinsic viscosity, IV is 0.85
No. 9, which was less than 1, had poor fatigue resistance and could not be used as a tire cord. No. 11 with COOH exceeding 25 eq / ton
Had a low IRT and poor heat resistance in rubber.

Tire uniformity, durability, excellent fatigue resistance and strength are all excellent, No. 2, 3, 4, 5, satisfying the conditions of the present invention
There were only 7,10 dip codes. In particular, among these, the No. 3 and No. 4 dip cords have heat resistance in rubber (IR
T) Both fatigue resistance were excellent.

FIG. 1 shows how the fatigue resistance changes with respect to dimensional stability S and strength T for dip cords No. 1 to 8 obtained from the same discharge yarn of a tip having an intrinsic viscosity IV of 1.42. It is shown.

As is clear from FIG. 1, the dip cords of Nos. 1, 2, 5, and 7 are at a level satisfying T ≧ 0.27 + 4.57, and the fatigue resistance is improved by more than 20% compared to the conventional product (reference cord) ( (Circle), and it can be seen that the dip cords of Nos. 3 and 4 show a level of satisfying T ≧ 0.27S + 5 and show an increase in fatigue resistance (◎) of 30% or more with respect to the reference code. Also, it can be seen that the strength T (strength after dip) of these dip codes is significantly higher than the reference code.

Example 2 A dip code as shown in Table 2 was obtained by changing the amounts of antimony trioxide and germanium dioxide used as the polymerization catalyst, and spinning and post-processing under the same conditions as in No. 4 of Example 1. Was. The heat resistance in rubber (IRT) of these dip cords was as shown in Table 2.

As is clear from Table 2, the amount of antimony (Sb) is 150 ppm.
No. 13 and 17 dip cords exceeding the limit and No. 16 dip cords with germanium (Ge) content exceeding 60 ppm had low heat resistance in rubber, and none of them satisfied the condition of IRT ≧ 8.57S + 8 . In particular, No. 17 having a large amount of antimony had only a remarkably low strength. In addition, the dip cord of No. 14 having less than 5 ppm of germanium had high COOH and also had poor heat resistance in rubber. 12 antimony
It can be seen that the No. 4 dip cord having 0 ppm or less and a germanium content of 7 to 20 ppm has particularly excellent heat resistance in rubber.

[Effects of the Invention] As described above, according to the present invention, by controlling the type and amount of catalyst remaining in the dip code, and controlling the code properties such as dimensional stability and strength, the conventional dip code Good heat resistance and fatigue resistance can be provided. Therefore, the polyester dip cord of the present invention can drastically reduce the amount of cord used for obtaining a tire of the same quality as the conventional one, and can achieve weight reduction and cost reduction.

[Brief description of the drawings]

FIG. 1 is a view showing a change in fatigue resistance with respect to dimensional stability and strength of a tire cord of the present invention. FIG. 2 is a diagram showing the relationship between dimensional stability and strength of a conventional tire cord.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) D02G 1/00-3/48 D02J 1/00-13/00

Claims (1)

(57) [Claims] 1. A polyester dip cord comprising an antimony compound of 150 ppm or less as antimony metal and 5 to 60 ppm of germanium compound as germanium metal and having the following physical properties. A. [Intermediate elongation + dry heat shrinkage] (S) (%) 7 ≦ S ≦ 9 B. Cord strength T (g / d) T ≧ 0.27S + 4.57 C. Intrinsic viscosity (IV) IV ≧ 0.85 D .Amount of carboxy terminal group [(COOH)] (eq / ton) (COOH) ≦ 25