JP2007303056A - Polyester fiber material having high heat-resistance, tire cord, dip cord and method for producing polyester fiber material having high heat-resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester fiber material, a tire cord, a dip cord and a method for producing the polyester fiber material having high heat-resistance, which provide high heat-resistance to keep the mechanical properties at a high temperature, especially above the melting point of the polyester and provide. <P>SOLUTION: The polyester fiber material having high heat-resistance is a polyester fiber having ethylene terephthalate unit as main repeating unit and satisfying the following properties (a) and (b) at the same time in dynamic viscoelasticity measurement. (a) The storage modulus (E') is ≥0.1 MPa at 275°C and (b) the main dispersion peak temperature of loss tangent (tanδ) is ≤148°C. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a polyester fiber material for rubber reinforcement applied to industrial materials such as tire cords, V belts, conveyor belts, hoses, and the like, and more specifically, mechanical properties at high temperatures, particularly above the melting point of ordinary polyester. It is related with the polyester fiber material for rubber reinforcement excellent in the high heat resistance which can hold | maintain.

  In general, polyester, nylon and rayon are well known as organic fibers as typical examples of fibers used as rubber reinforcing materials, particularly as rubber reinforcing materials for tires, and steel and glass fibers are known as inorganic fibers. It is representative. These materials are used in place due to their inherent properties.

  In recent years, with the progress of radial tire structures, the demand for high elastic modulus, low shrinkage, fatigue resistance, and cost reduction has increased for fiber materials used in carcass materials. As a result, polyester fibers, which are organic fibers excellent in physical properties and cost, are widely used as an alternative to rayon and nylon.

  Further, in recent years, run flat tires have been developed that can run at a predetermined speed over a certain distance even if the tire pressure becomes 0 kPa due to puncture. This run-flat tire has a side reinforcement type that is reinforced by placing a relatively hard rubber layer with a crescent cross section on the inner surface of the carcass from the bead portion of the tire sidewall to the shoulder area, and the rim portion in the tire air chamber. Further, a core type in which a ring core made of metal or synthetic resin is attached is known.

  Of these, the side-reinforcement type can support the load by the inherent rigidity of the sidewall reinforced with a reinforcing rubber layer and run at a predetermined speed at a predetermined speed if the tire punctures and the air escapes during driving. Is possible. However, if the run-flat running is continued, the reinforcing rubber layer generates heat due to repeated compression and expansion, and the tire internal temperature may become extremely high such as 200 ° C. or more, and more locally. For this reason, rayon fibers, aramid fibers, steel, etc., which are excellent in heat-resistant melting property, have been proposed and used as preferred cord materials for the carcass ply cords of run-flat tires.

  On the other hand, tire cords made of polyester fiber or nylon fiber start to break the adhesion interface with tire rubber at high temperatures of 150 to 200 ° C., and the strength and elastic modulus rapidly decrease. As a cord material for run-flat tires, it is not suitable as a cord material for run-flat tires. However, since these fibers are very rich in supply, cheap in price, and light in weight, run cords made from these polyester fibers and nylon fibers are used to make run-flat tires more widespread. It is hoped that.

  So far, various methods for improving the heat resistance of the polyester tire cord in the tire rubber have been proposed. For example, a method for suppressing hydrolysis in rubber by reducing the amount of terminal carboxylic groups of polyester fibers (see, for example, Patent Document 1 and Patent Document 2), a polymer comprising acrylic acid and / or methacrylic acid (For example, see Patent Document 3), a method for containing a fluorine-based polymer (for example, see Patent Document 4), a method for containing a cyclic olefin polymer (for example, see Patent Document 5), and the like. . However, these are all improvements in strength properties relating to heat resistance at 150 to 160 ° C., and were not able to maintain the shape above the melting point of the polyester and maintain the predetermined strength and elastic modulus.

JP 61-252332 A JP-A-7-166420 JP-A-55-166235 JP-A-6-264307 JP-A-8-74126

  The present invention has been made in view of the above-mentioned problems, and its object is to provide a high heat-resistant polyester fiber material, tire cord, dip, which can maintain mechanical properties at high temperatures, particularly above the melting point of ordinary polyester. A cord and a method for producing a high heat-resistant polyester fiber material are provided.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive research. As a result, at least one of the fibers is obtained by reacting a compound having a specific structure at the end of the polyester molecular chain and irradiating it with an electron beam after melt spinning. The present inventors have found that this problem can be solved by forming a crosslinked structure in the part, and have completed the present invention.

  That is, the present invention is as follows.

1. A polyester fiber having an ethylene terephthalate unit as a main repeating unit, which simultaneously satisfies the following characteristics (a) and (b) in dynamic viscoelasticity measurement.
(A) Storage elastic modulus at 275 ° C. (E ′) ≧ 0.1 MPa
(B) Main dispersion peak temperature of loss tangent (tan δ) ≦ 148 ° C.

2. 2. The high heat-resistant polyester fiber material as described in 1 above, wherein the strength is 4.0 cN / dtex or more.

3. A polyester tire cord using the high heat-resistant polyester fiber material described in 1 or 2 above.

4). A polyester tire cord for a run-flat tire using the high heat-resistant polyester fiber material described in 1 or 2 above.

5. 3. A polyester dip cord, wherein the high heat-resistant polyester fiber material according to 1 or 2 is subjected to a dip treatment with a treatment liquid containing at least a resorcin-formaldehyde-latex (RFL) mixed solution.

6). 6. The polyester dip cord according to 5 above, which uses a tire cord.

7). The polyester dip cord according to 5 above, which uses a tire cord for run-flat tires.

8). Polyester having ethylene terephthalate unit as the main repeating unit is blended with 0.2 to 3.0% by weight of the following compound 1, and melt-spun at a spinning speed of 2000 m / min. A process for producing a highly heat-resistant polyester fiber material, characterized by irradiating ionized radiation to a drawn yarn, a twisted cord obtained by twisting one or more drawn yarns, or a woven fabric woven from the twisted cord.

9. 9. The method for producing a high heat-resistant polyester fiber material as described in 8 above, wherein the birefringence of the undrawn yarn is 0.04 or more.

10. 10. The method for producing a high heat-resistant polyester fiber material as described in 8 or 9 above, wherein the density of the undrawn yarn is 1.340 g / cm ² or more.

  ADVANTAGE OF THE INVENTION According to this invention, the polyester fiber material for high heat resistance rubber reinforcement which can maintain a mechanical characteristic at the high temperature, especially above melting | fusing point of polyester, and its manufacturing method can be provided.

  Hereinafter, the present invention will be described in detail. As described above, the present invention can be used as a carcass ply cord for a run-flat tire that may be punctured to lower the internal pressure and have a tire internal temperature of 200 ° C. or higher, and locally a very high temperature higher than the melting point of polyester. Provided is a polyester fiber material for rubber reinforcement that has a highly improved heat resistance and can maintain a predetermined strength and elastic modulus at a high temperature, particularly above the melting point of ordinary polyester that does not have a crosslinked structure. It is.

  The polyester in the present invention is a polyester having terephthalic acid as the main acid component and at least one glycol, preferably at least one alkylene glycol selected from ethylene glycol, trimethylene glycol, and tetramethylene glycol as the main glycol component. And Moreover, the polyester which replaced a part of terephthalic acid with the other bifunctional carboxylic acid component may be sufficient, and / or the polyester which replaced a part of glycol component with the said glycol other than a main component, or another diol component It may be. Examples of the bifunctional carboxylic acid other than terephthalic acid used here include isophthalic acid, naphthalenedicarboxylic acid, diphenylcarboxylic acid, diphenoxyethanedicarboxylic acid, β-hydroxyethoxybenzoic acid, p-oxybenzoic acid, and adipic acid. And aromatic, aliphatic and alicyclic bifunctional carboxylic acids such as sebacic acid and 1,4-cyclohexanedicarboxylic acid. Examples of the diol component other than the glycol include aliphatic, alicyclic and aromatic diol compounds such as cyclohexane-1,4-dimethanol, neopentyl glycol bisphenol A and bisphenol S, and polyoxyalkylene glycol. be able to. Furthermore, within the range in which the polyester is substantially linear, carboxylic acids such as trimellitic acid and pyromellitic acid, polyols such as glycerin, trimethylolpropane and pentaerythritol, 5-hydroxyisophthalic acid, 3,5-dihydroxybenzoic acid A monomer having a trifunctional or higher functional ester-forming group as shown below can be used.

  Furthermore, a small amount of other optional polymers, antioxidants, radical scavengers, antistatic agents, dyeing improvers, dyes, pigments, matting agents, fluorescent brighteners, inert fine particles and other additives are added to the polyester. An agent may be contained.

  As a method for obtaining such a polyester, it is not necessary to employ special polymerization conditions, and it is employed when a reaction product of a dicarboxylic acid component and / or an ester-forming derivative thereof and a glycol component is polycondensed into a polyester. Can be synthesized by any method. The polymerization apparatus may be a batch type or a continuous type. Furthermore, after the polyester obtained in the liquid phase polycondensation step is granulated and pre-crystallized, it can also be subjected to solid phase polymerization in an inert gas atmosphere or under reduced pressure vacuum at a temperature below the melting point.

  The polymerization catalyst is not particularly limited as long as it has a desired catalytic activity, but an antimony compound, a titanium compound, a germanium compound, and an aluminum compound are preferably used. When these catalysts are used, they may be used alone or in combination of two or more, and the amount used is preferably 0.002 to 0.1 mol% with respect to the carboxylic acid component constituting the polyester.

  Further, the intrinsic viscosity (IV) of the polyester in the present invention is preferably 0.6 dl / g or more, more preferably 0.8 dl / g or more. When the IV is less than 0.6 dl / g, the strength and elastic modulus are greatly reduced due to thermal deterioration of the yarn, which is not preferable. Moreover, it is preferable that the amount of carboxyl terminal groups of polyester is 50 eq / ton or less, More preferably, it is 30 eq / ton or less. If it exceeds 50 eq / ton, the heat resistance in the rubber tends to be insufficient, and the durability as a tire cord tends to be insufficient.

  The polyester fiber material of the present invention is, for example, a drawn yarn obtained by hot drawing an undrawn yarn obtained by melt spinning the above polyester, a twisted cord obtained by twisting several yarns, or a knit fabric woven from it. There is no particular upper limit to the number of twisted drawn yarns, but it is usually 10 or less.

  The polyester fiber material of the present invention retains mechanical properties at a temperature equal to or higher than the melting point of ordinary polyester, and has a storage elastic modulus (hereinafter referred to as E ′) of 0.1 MPa or more at 275 ° C. in dynamic viscoelasticity measurement. Preferably, it is 0.5 MPa or more, more preferably 1.0 MPa or more. If E ′ at 275 ° C. is melted at a temperature of less than 0.1 MPa or less than 275 ° C., it is not preferable because it breaks in the reinforced rubber. The measurement of E ′ is performed by using, for example, DMA instrument Q-800 manufactured by TA Instruments Inc., a sample aligned to have a thread length of 1 cm and 12000 dtex, an initial load of 0.01 N, a minimum dynamic force of 0.00001 N, It can be determined by measuring at a rate of temperature increase of 2 ° C./min for a temperature range of 200 ° C. to 370 ° C. under the conditions of ForceTrack 125%, amplitude 10 μm, and frequency 11 Hz. Further, when the sample was melt fractured during the measurement, the temperature was taken as the melt fracture temperature. However, there is no particular upper limit to 275 ° C. E ′, but it is usually 1000 MPa or less and often 10 MPa or less.

  The polyester fiber material of the present invention has a crosslinked structure in at least a part between the polyester molecular chains, and the crosslinked structure is an aliphatic of a compound represented by the following chemical formula (1) introduced at the terminal of the polyester molecule. It is preferable that the unsaturated group is formed by reacting by irradiation with ionizing radiation. The ionizing radiation is preferably an electron beam or γ-ray having a large irradiation transmission power, but is not limited thereto.

  In general, it is well known that the heat-resistant melting property is improved or the solubility in a solvent is lowered by forming a crosslinked structure in the polymer, and these can serve as an index indicating the degree of crosslinking (crosslinking degree). . The heat flow starting temperature of the polyester fiber material in the present invention is not less than the melting point of the polyester resin before forming the crosslinked structure, preferably not less than 265 ° C., more preferably not less than 280 ° C., and still more preferably not less than 300 ° C. If it melts and flows at a temperature lower than the melting point, the shape cannot be maintained in the reinforced rubber and breaks, which is not preferable. The measurement of the heat flow start temperature can be made by visually or microscopically determining whether the sample is hot melt flowing after placing the sample on a hot plate that can be set to a constant temperature for 1 minute.

  Moreover, it is preferable that the gel fraction which shows the ratio of the insoluble residue with respect to a predetermined solvent is 10 weight% or more, More preferably, it is 20 weight% or more, More preferably, it is 30 weight% or more. If the gel fraction is lower than 10% by weight, the degree of crosslinking is too low, and the dimensional stability and strength of the tire cord at high temperatures are insufficient, which is not preferable. The solvent for measuring the gel fraction is not particularly limited as long as it is an organic solvent that completely dissolves the aromatic polyester before forming a crosslinked structure at a predetermined temperature and a predetermined time. For example, phenol, o-chlorophenol , M-chlorophenol, p-chlorophenol, 2,3-dichlorophenol, 2,4-dichlorophenol, 2,5-dichlorophenol, 2,6-dichlorophenol, 3,4-dichlorophenol, 3,5- Dichlorophenol, 2,3,4-trichlorophenol, 2,3,5-trichlorophenol, 2,3,6-trichlorophenol, 2,4,5-trichlorophenol, 2,4,6-trichlorophenol, 3, 4,5-trichlorophenol, 1,1,1,2-tetrachloroethane, 1,1,2,2-tetrachloroe Down, chloroform, can be exemplified dichloromethane, carbon tetrachloride, dichloro acetic acid, hexafluoroisopropanol and the like, which may be used in combination one kind even or two or more kinds. Although the temperature of the solvent at the time of melt | dissolution is not specifically limited, For example, it is 20 to 200 degreeC. The dissolution time is not particularly limited, but may be a time required for the dissolution to reach a saturated state, for example, 10 minutes to 5 hours.

  Furthermore, in the polyester fiber material of the present invention, the main dispersion peak temperature of tan δ (hereinafter referred to as Tα) in the measurement of the dynamic viscoelasticity at 110 Hz of the drawn yarn is preferably 148 ° C. or less, more preferably 147 ° C. or less. It is. When Tα is higher than 148 ° C., the high elastic modulus and low shrinkage required for tire cords, particularly carcass ply cords, are not sufficiently exhibited. Here, Tα is an index showing the degree of microstructural amorphous chain restraint, and a low Tα means that amorphous chain restraint is weak, and as a result, excellent thermal dimensional stability. Is expressed. The drawn yarn having a Tα of 148 ° C. or lower of the present application is, for example, about 1.5 to 3.0 times the highly oriented undrawn yarn (so-called POY) taken at a relatively high spinning speed of 2000 m / min or more, which will be described later. It can be obtained by hot drawing at a low draw ratio.

  The polyester fiber material in the present invention is, for example, melt-spun by adding a compound represented by the chemical formula (1) to a polyester having an ethylene terephthalate unit as a main repeating unit at an arbitrary position in an extruder supply port or a melt extrusion process. However, the compound and polyester may be melt-kneaded and pelletized by a known method in advance and used for melt spinning. Further, this kneaded resin can be used as a master batch by blending with a polyester resin. The temperature at the time of melt-kneading is not particularly limited as long as it is substantially equal to or higher than the melting point of the polyester. However, if the temperature is excessively high, the polymer chain is broken due to thermal deterioration, which is not preferable. The melting point is preferably in the range of (melting point + 70 ° C.). Also, the time for melt kneading is not particularly limited, but is 1 minute to 40 minutes, preferably 2 minutes to 20 minutes.

  In the present invention, the compounding amount of the compound represented by the chemical formula (1) with respect to the polyester is preferably 0.2 to 3.0% by weight. More preferably, it is 0.4 to 2.5% by weight. When the blending amount is less than 0.2% by weight, the crosslinked structure that appears after irradiation with ionizing radiation is not sufficient, and it becomes difficult to maintain the mechanical characteristics at the melting point or higher, which is not preferable. Since this property is basically proportional to the content of the compound represented by the chemical formula (1), sufficient thermodynamic properties can be imparted by increasing the blending amount. However, a blending amount exceeding 3.0% by weight is not preferable because the spinnability is lowered and it is difficult to obtain a spinning speed for expressing a high elastic modulus and low shrinkage. Furthermore, it is difficult to obtain a high draw ratio and to obtain high strength. This is because an excessive compound represented by the chemical formula (1) is crosslinked by heat at the time of spinning to form a gelled product. When the gelled product is generated, it is difficult to produce industrially stable production. In addition, since the measurement of the content is soluble in a predetermined solvent before irradiation with ionizing radiation, it can be determined by, for example, H-NMR measurement and IR measurement, and after irradiation with ionizing radiation, the solvent However, it is not limited to these measurements as long as the content of the compound represented by the chemical formula (1) can be obtained.

  The compound represented by the chemical formula (1) reacts with the epoxy group and the carboxyl group terminal of the polyester by melt-kneading with the polyester, and a catalyst for promoting this reaction may be added at the same time. The catalyst is not particularly limited and used, for example, an alkali metal compound represented by sodium acetate, potassium acetate, lithium acetate, sodium stearate, potassium stearate, lithium stearate and the like, barium acetate, magnesium acetate, Alkaline earth metal compounds such as strontium acetate, barium stearate, magnesium stearate, strontium stearate, triethylamine, tributylamine, trihexylamine, triethanolamine, triethylenediamine, dimethylbenzylamine, pyridine, picoline, etc. Tertiary amines, imidazole compounds such as 2-methylimidazole, 2-ethylimidazole, 2-isopropylimidazole, tetramethylammonium chloride, Quaternary ammonium salts such as laethylammonium chloride, trimethylbenzylammonium chloride, triethylbenzylammonium chloride, phosphine compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, trioctylphosphine, triphenylphosphine, tetramethylphosphonium bromide, tetrabutyl Phosphonium salts such as phosphonium bromide, tetraphenylphosphonium bromide, triphenylbenzylphosphonium bromide, phosphate esters such as trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, oxalic acid, p-toluenesulfonic acid, dinonylnaphthalenedisulfonic acid , Dodecylbenzenesulfonic acid Organic acids, boron trifluoride, aluminum tetrachloride, titanium tetrachloride, etc. Lewis acids such as tin tetrachloride may be exemplified. These can be used alone or in combination of two or more. Of these, alkali metal compounds, alkaline earth metal compounds, phosphine compounds, and phosphate ester compounds are preferably used. Although the addition amount of a catalyst is not specifically limited, 0.001-1 weight part is preferable with respect to 100 weight part of polyester, Furthermore, it is 0.01-0.5 weight part.

  In the present invention, it is preferable that a crosslinking group is introduced by the reaction between the compound represented by the chemical formula (1) and the carboxyl group terminal of the polyester, but the heat resistance is also reduced by reducing the amount of the carboxyl group terminal of the polyester. Contributes to improvement. That is, it is thought that the carboxyl group terminal of the polyester fiber material causes a degradation reaction of the polyester by autocatalysis in the rubber, but this degradation reaction is also suppressed by blocking the carboxyl group terminal by the reaction of the above compound. .

  For example, a polyester containing a compound represented by the chemical formula (1) melted and kneaded by an extruder is melted and discharged from a spinneret, and then cooled and solidified by cooling air in a spinning cylinder, and a spinning speed of 2000 m / min or more. It is preferably taken up at 2500 m / min or more. This yarn is referred to as an undrawn yarn. A spinning speed of 2000 m / min or less is not preferable because sufficient spinning stress cannot be applied to promote orientation crystallization during spinning. However, if the spinning speed becomes too high, the unstretched birefringence and density become excessively large, so that it is difficult to stretch and it is difficult to obtain high strength. Therefore, it is preferably set to 6000 m / min or less, more preferably 4500 m / min. Is less than a minute. Further, the birefringence of the obtained undrawn yarn is 0.04 or more, preferably 0.05 or more, more preferably 0.06 or more. A birefringence of less than 0.04 is not preferable because the high elastic modulus and low shrinkage required for tire cords, particularly carcass ply cords, are not sufficient. However, if the birefringence of the undrawn yarn becomes too large, it becomes difficult to draw and it becomes difficult to obtain high strength.

Further, the density of the undrawn yarn is preferably 1.340 g / cm ² or more. More preferably, it is 1.345 g / cm < ² > or more, More preferably, it is 1.350 g / cm < ² > or more. When the density is less than 1.340 g / cm ² , the development of high elastic modulus and low shrinkage is not sufficient. However, if the density of the undrawn yarn becomes too large, it becomes difficult to draw and it is difficult to obtain high strength. The temperature of the cooling air is not particularly limited as long as it satisfies the desired birefringence and density, but is preferably 20 to 80 ° C, more preferably 40 to 70 ° C.

  A drawn yarn can be obtained by winding the undrawn yarn taken up once or by hot drawing by a spin draw method of drawing continuously after spinning. The thermal stretching is performed by high-strength one-stage stretching or two-stage or more multi-stage stretching. The heating method includes a method using a heating roller, superheated steam, a heat plate, a heat box, or the like, and is not particularly limited. The stretching ratio can be stretched at any value depending on the desired physical properties, but is preferably 1.5 to 3.0 times.

  The drawn yarn thus obtained was twisted 10 to 100 times per 10 cm (bottom twist) in accordance with a conventional method, and then a plurality of yarns were combined and twisted 10 to 100 times per 10 cm in the opposite direction (upper A twisted cord (raw cord) is formed. Furthermore, a woven fabric (raw fabric) can be obtained from this twisted yarn cord according to a conventional method. Although the total number of twisted yarns is not particularly limited, it can be generally said that it is 10 or less.

  The cross-linked structure of the polyester fiber material in the present invention is, for example, a structure caused by an aliphatic unsaturated group of the compound represented by the chemical formula (1) introduced at the terminal of the polyester molecule. It is preferably formed by irradiation. The ionizing radiation is preferably an electron beam or γ-ray having a large irradiation transmission power, but is not limited thereto. This irradiation with ionizing radiation can be carried out in any process from the spinning process of the polyester fiber to the manufacturing process of the dip counter. However, in terms of irradiation efficiency and quality stability, undrawn yarn, drawn yarn or twisted yarn It is preferable to irradiate in the state of a cord or a woven fabric. The irradiation dose of ionizing radiation is not particularly limited as long as the desired physical properties are satisfied, but is 20 to 3000 kGy, preferably 50 to 1500 kGy. If the irradiation dose is too low, the degree of cross-linking tends to be insufficient, and if it is too high, the polyester is decomposed and the strength properties are deteriorated, which is not preferable. The irradiation process is generally performed at room temperature, but can be performed in an arbitrary temperature environment of 0 to 200 ° C. The atmosphere gas may be air or an inert gas, but it is preferable to irradiate in an inert gas because oxygen may inhibit the crosslinking reaction.

  The strength of the polyester fiber material in the present invention is preferably 4.0 cN / dtex or more. More preferably, it is 5 cN / dtex, More preferably, it is 6.0 cN / dtex or more. If the strength is less than 4.0 cN / dtex, not only the physical properties of the final product but also the process passability in the production process is lowered, which is not preferable. It can be said that the higher the strength, the better, but it is usually 10 cN / dtex or less.

  Furthermore, the polyester fiber material in the present invention can be subjected to a dip treatment for imparting adhesiveness to rubber to obtain a dip cord or a dip anti-dip. The dip treatment liquid is preferably a treatment liquid containing at least a resorcin-formaldehyde-latex (RFL) mixed liquid. The details of the dip process are those described in Japanese Patent Application Laid-Open No. 2006-2327.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In addition, the evaluation method of various characteristics followed the following.

(1) Dynamic viscoelasticity a. Storage modulus (E ')
Samples aligned to a thread length of 1 cm and 12000 dtex using DMA instrument Q-Q 800 manufactured by TA Instruments Inc., initial load 0.01N, Minimum Dynamic Force 0.00001N, ForceTrack 125%, amplitude 10 μm, frequency Under a condition of 11 Hz, a temperature range of 200 ° C. to 370 ° C. was measured at a rate of temperature increase of 2 ° C./min, and storage elastic modulus (E ′) was determined. If the sample melts and breaks during measurement,
The temperature was defined as the melt fracture temperature (° C.).
In addition, the measurement sample shall use untwisted drawn yarn, and in the case of a twisted cord or woven fabric, each is untwisted and returned to the state of the untwisted drawn yarn.
b. Loss tangent (tan δ) main dispersion peak temperature Samples aligned to a yarn length of 2 cm and 1500 dtex using DMA-Q800 manufactured by T.A. Instrument Co., Ltd., initial load 0.049 N, Minimum Dynamic Force 0 Under the conditions of 0.0001N, Force Track 250%, amplitude 10 μm, frequency 110 Hz, the temperature range of 30 ° C. to 200 ° C. is measured at a rate of temperature increase of 2 ° C./min, and the main dispersion peak temperature of loss tangent (tan δ) is obtained. It was.
In addition, the measurement sample shall use untwisted drawn yarn, and in the case of a twisted cord or woven fabric, each is untwisted and returned to the state of the untwisted drawn yarn.

(2) Gel fraction 25 ml of parachlorophenol / 1,1,2,2-tetrachloroethane = 3/1 mixed solvent was added to 0.1 g (weighed) of the sample and immersed at 90 ° C. for 100 minutes, and then 30 ° C. The residue obtained by suction filtration with a glass filter was dried under reduced pressure, and the weight percent of the insoluble matter was defined as the gel fraction (%).

(3) Strength Using “Tensilon” manufactured by Orientic Co., Ltd., with a sample length of 20 mm (length between chucks), an elongation rate of 100% / min, a stress-strain curve at an ambient temperature of 20 ° C. and a relative humidity of 65% The value obtained by dividing the stress at the breaking point by the fineness was obtained as the strength (cN / dtex). As each value, an average value of five measurements was used.
In addition, the measurement sample shall use untwisted drawn yarn, and in the case of a twisted cord or woven fabric, each is untwisted and returned to the state of the untwisted drawn yarn.

(4) Intrinsic viscosity [IV]
The polymer was dissolved in a mixed solvent of parachlorophenol / 1,1,2,2-tetrachloroethane = 3/1 at a concentration of 0.4 g / dl and measured at 30 ° C. (dl / g).

(5) Melting point Melting when 10 mg of a sample was measured for an exothermic / endothermic curve (DSC curve) in a nitrogen stream using a differential scanning calorimeter MacScience DSC 3100S at a heating rate of 20 ° C./min. The apex temperature of the endothermic peak accompanying this was defined as the melting point Tm (° C.).

(6) Using a birefringence deflection microscope, measurement was performed by the Belek Compensator method.

(7) Using a density calcium nitrate aqueous solution, measurement was performed at 30 ° C. by a density gradient tube method.

(8) Spinning status The spinning status was evaluated based on yarn breakage. Sampling is possible when there is no thread breakage for 1 hour or more and stable winding is possible, and sampling is possible, but Δ when the thread breakage occurs in less than 1 hour, stable winding due to frequent thread breakage The case where it was impossible was set as x.

(9) Dip cord strong elongation In accordance with JIS-L1017, after standing in a temperature-controlled room at 20 ° C. and 65% RH for 24 hours or more, it is strong with a tensile tester at a load of 2.0 cN / dtex. The elongation (hereinafter referred to as intermediate elongation) and cutting elongation were measured. Here, the cord strength is a value obtained by dividing the cord strength by the reference fineness in the cord configuration. For example, if two yarns of 1440 dtex are twisted together, the standard fineness is 2880 dtex, and the intermediate elongation load is 57.6 N.

(10) Dip code shrinkage rate In accordance with JIS-L1017, after leaving in a temperature-controlled room at 20 ° C and 65% RH for 24 hours or longer, heat treatment is performed at 150 ° C for 30 minutes under no load in the dryer. It was determined from the test length difference before and after this heat treatment.

(11) Dip Code Dimensional Stability Index The sum of intermediate elongation and shrinkage rate of the dip cord was used as an index of dimensional stability. A smaller value means better dimensional stability.

(Examples 1-3)
In a reactor, 100 mole parts of terephthalic acid, 200 mole parts of ethylene glycol, 0.025 mole part of antimony trioxide, and 0.3 mole part of triethylamine as a stabilizer are subjected to dehydration reaction at 250 ° C. and an internal pressure of 2.5 kg / cm 2 for 150 minutes. Went. Thereafter, the temperature was gradually raised and reduced, and a polycondensation reaction was performed at 275 ° C. and 0.1 mmHg to a predetermined torque. After completion of the reaction, the polymer was converted into chips according to a conventional method, and further solid phase polymerization was performed at 230 ° C. under a vacuum of 0.01 mmHg to obtain polyethylene terephthalate chips having an intrinsic viscosity of 1.05. The chip was dried according to a conventional method, and then fed to a melt extruder and simultaneously diallyl monoglycidyl isocyanurate heated to 50-60 ° C. from the extruder inlet was 0.5% by weight in Example 1 with respect to the polymer. In Example 2, it was added at a constant flow rate so as to be 1.3% by weight and in Example 3 to be 2.5% by weight. The kneaded polymer was discharged from a spinneret at 310 ° C. having 336 orifices having a hole diameter of 0.5 mm, cooled and solidified with cooling air at 70 ° C. and 1.0 m / sec, and after spinning, a spinning speed of 3000 m Taken at 1 min / min and without winding, stretched 1.30 times at 70 ° C., stretched 1.31 times at 90 ° C., heat treated at 210 ° C., and 4.0% relaxation at 130 ° C. It was processed to obtain a drawn yarn of 1440 dtex, 336 filament. The drawn yarn was irradiated with an electron beam with an acceleration voltage of 300 keV in a nitrogen atmosphere at a constant tension of 500 kGy. The results are shown in Table 1, and it was found that E ′ was maintained at 0.1 MPa or higher without melt fracture even at a temperature of 275 ° C. or higher in the dynamic viscoelasticity measurement. Furthermore, from the comparison of Examples 1, 2, and 3, it was found that by increasing the blending amount of diallyl monoglycidyl isocyanurate, E ′ at 275 ° C. was increased and the melt fracture temperature was increased.

Subsequently, two drawn yarns after the electron beam irradiation were twisted together to obtain a raw cord of 1440 dtex / 2 and a twist number of 43 × 43 (t / 10 cm).
Further, after the cord is immersed in a mixed solution of a blocked isocyanate aqueous solution and a chlorophenol-resorcin-formaldehyde (RF) condensate as a first treatment liquid in order to impart adhesiveness to rubber to the raw cord. , Dried in an oven at 120 ° C. for 56 seconds, and then heat-treated in an oven at 235 ° C. for 45 seconds while applying a tension of 0.5 cN / dtex. Subsequently, the cord was immersed in a mixed solution of resorcin-formaldehyde-latex (RFL), a blocked isocyanate aqueous solution, and an aqueous dispersion of an epoxy compound as the second treatment liquid, and then dried in an oven at 120 ° C. for 56 seconds, then 0. While applying a tension of 5 cN / dtex, heat treatment was performed in an oven at 235 ° C. for 45 seconds to obtain a dip cord.

Example 4
A drawn yarn, a drawn yarn after electron beam irradiation, and a dip cord were obtained in the same manner as in Example 1 except that the spinning speed was 2200 m / min, the single-stage draw ratio was 1.50 times, and the two-stage draw ratio was 1.33 times. It was. Table 1 shows the results. Although there was no significant difference in E ′ at 275 ° C., it was found that Tα was high and the dimensional stability of the dip cord was slightly deteriorated.

(Example 5)
Table 1 shows the results of setting the electron beam irradiation amount to 1000 kGy in Example 1. It was found that E ′ at 275 ° C. was increased, although the strength was slightly reduced as compared with Example 1.

(Comparative Example 1)
A drawn yarn, a drawn yarn after electron beam irradiation, and a dip cord were obtained in the same manner as in Example 1 except that diallyl monoglycidyl isocyanurate was not added. The results are shown in Table 1. It was found that melt fracture occurred at 268 ° C., and that E ′ at 275 ° C. could not be maintained even when a normal polyethylene terephthalate fiber was irradiated with an electron beam of 1000 kGy.

(Comparative Example 2)
The result of not irradiating with an electron beam in Example 1 is shown in Table 1. It was found that melt fracture occurred at 268 ° C. and E ′ at 275 ° C. could not be maintained.

(Comparative Example 3)
A drawn yarn, a drawn yarn after electron beam irradiation, and a dip cord were obtained in the same manner as in Example 1 except that the spinning speed was 500 m / min, the one-stage draw ratio was 3.5 times, and the two-stage draw ratio was 1.23 times. It was. Table 1 shows the results. Although there was no significant difference in E ′ at 275 ° C., it was found that Tα increased to 150 ° C. and the dimensional stability of the dip cord was greatly deteriorated.

(Comparative Example 4)
Although diallyl monoglycidyl isocyanurate was adjusted to 3.5% by weight with respect to the polymer and melt extrusion was performed, smoke and thread breakage occurred frequently, and stable winding was impossible.

  The heat-resistant polyester fiber material of the present invention is characterized in that it has a crosslinked structure at least partly between the polyester molecular chains, and does not melt even at a high temperature above the melting point of the polyester and retains mechanical properties. Since it is possible, it is suitable for rubber reinforcement applications exposed to high temperatures, particularly for tire cords for run-flat tires.

Claims (10)

A polyester fiber having an ethylene terephthalate unit as a main repeating unit, which simultaneously satisfies the following characteristics (a) and (b) in dynamic viscoelasticity measurement.
(A) Storage elastic modulus at 275 ° C. (E ′) ≧ 0.1 MPa
(B) Main dispersion peak temperature of loss tangent (tan δ) ≦ 148 ° C.   The high heat-resistant polyester fiber material according to claim 1, wherein the strength is 4.0 cN / dtex or more.   A polyester tire cord using the high heat-resistant polyester fiber material according to claim 1.   A polyester tire cord for a run-flat tire using the high heat-resistant polyester fiber material according to claim 1.   A polyester dip cord, wherein the highly heat-resistant polyester fiber material according to claim 1 or 2 is subjected to a dip treatment with a treatment solution containing at least a resorcin-formaldehyde-latex (RFL) mixed solution.   The polyester dip cord according to claim 5, which uses a tire cord.   The polyester dip cord according to claim 5, which uses a tire cord for a run-flat tire. The polyester having ethylene terephthalate unit as the main repeating unit was blended with 0.2 to 3.0% by weight of the following compound 1 and melt-spun at a spinning speed of 2000 m / min or more, and the undrawn yarn was hot-drawn. A method for producing a highly heat-resistant polyester fiber material, characterized by irradiating a drawn yarn, a twisted cord obtained by twisting one or more drawn yarns, or a knit fabric woven with the twisted cord with ionizing radiation.

  The method for producing a high heat-resistant polyester fiber material according to claim 8, wherein the birefringence of the undrawn yarn is 0.04 or more. The method for producing a high heat-resistant polyester fiber material according to claim 8 or 9, wherein the density of the undrawn yarn is 1.340 g / cm ² or more.