JP2006307381A - Heat-resistant cross-linked polyester fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide polyester fibers which maintain characteristics such as dimensional stability, high strength and durability and are simultaneously thermally not melted at high temperature or have excellent heat resistance, and to provide a material useful as the belt and carcass member of a tire from the fibers. <P>SOLUTION: The heat-resistant cross-linked polyester fibers which have excellent heat resistance and in which or in whose surface layers an unsaturated compound is cross-linked are characterized by immersing polyester fibers comprising a copolyester in a compound having at least two unsaturated groups and then irradiating the treated fibers with electron beams or γ-rays. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a heat-resistant crosslinked polyester fiber. More specifically, it provides heat-resistant cross-linked polyester fibers that have dimensional stability, high strength, durability, etc., and are excellent in heat resistance, and are useful for industrial materials such as tire cords, belt materials, canvas, and screen bags. To do.

  Conventionally, organic fibers such as nylon fibers, rayon fibers, and polyester fibers have been used for tire cords as tire fiber reinforcing materials. When nylon fibers are used for tire cords, although they have high toughness and good adhesion to rubber, they have a relatively large elongation, so that they have poor dimensional stability and are liable to cause a flat spot phenomenon. In addition, when rayon fibers are used for tire cords, the strength is lower than that of the nylon fiber tire cords. For this reason, when used for tire carcass members, the amount used must be increased, resulting in tire weight. There is a disadvantage that increases. Furthermore, there are concerns about the future supply of rayon fiber pulp. For this reason, attention has been paid to the use of polyester fiber having excellent dimensional stability and high strength as a tire cord as a material to compensate for the disadvantages of both.

  In recent years, the need for run-flat tires has increased due to the improvement in safety of automobiles. A run-flat tire is a tire that can travel at a predetermined speed over a certain distance even when the tire punctures during high-speed traveling and the tire internal pressure becomes 0 KPa. This run-flat tire has a side reinforcement type that is reinforced by placing a relatively hard rubber layer with a crescent-shaped cross section on the inner surface of the carcass from the beat part of the tire sidewall to the shoulder area, and the rim part in the tire air chamber. A core type having a ring core made of metal or synthetic resin is known.

  This inner side reinforcement type supports the load by the rigidity inherent to the side wall reinforced with a reinforcing rubber layer when the tire punctures and the air escapes during driving, and it can run for a predetermined distance, but it is flexible at high loads. In the case of a large tire, frictional heat is generated due to contact with the road surface, and the temperature inside the tire may be 200 ° C. or higher, and may be extremely high locally. Thus, the main cause of tire failure is deterioration due to heat generation. Therefore, particularly in the case of run-flat tires, heat-resistant rayon fibers, aramid fibers, steel, and the like are used as carcass members.

  On the other hand, when nylon fiber or polyester fiber is used for a carcass member of a run-flat tire, heat begins to break at an adhesive interface with the tire rubber due to heat generation near 200 ° C., and strength and dimensional stability rapidly decrease. When heat generation at a temperature of 0 ° C. or higher occurs, the melting point of the nylon fiber or polyester fiber is exceeded, so that heat melting occurs and the role as a reinforcing material cannot be maintained. Therefore, it has been restricted or unsuitable for applications requiring heat resistance as well as belts and other textile cords as well as carcass members for run-flat tires.

  Polyester fibers made of copolymerized polyethylene terephthalate are less expensive than rayon fibers, and it is commercially advantageous if they are given a heat-resistant function. Furthermore, if the application of heat-resistant function is applied to polyethylene naphthalate fibers and nylon fibers made of copolymerized polyethylene naphthalate, the usage can be expanded and useful.

  Accordingly, various proposals have been made to solve the problem of polyester fibers. For example, a method of imparting a polymer comprising acrylic acid and / or methacrylic acid (see Patent Document 1), a method of containing an epoxy compound or a specific diepoxy compound with respect to the polyester and reducing the terminal amount of the carboxy group of the polyester (patent References 2 to 4) and methods for reducing the amount of terminal carboxy groups by incorporating a carbodiimide compound into polyester (see Patent Documents 5 to 9) are disclosed. These methods are effective as a means for reducing water molecules generated by the neutralization reaction of amine compounds in rubber with carboxy end groups from attacking and hydrolyzing the ester bond of polyester. It does not solve the inherent lack of heat resistance.

  Further, as a method for preventing the deterioration of the carcass member in the rubber, a method of protecting by a dipping method after coding (see Patent Documents 10 to 12) is disclosed. However, all of these only prevent and protect the fiber surface from entering the amine compound, and the internal structure has not been modified, and the expected effect is small.

  Therefore, a method of coding using oriented and crystallized drawn yarn obtained under specific polyester fiber production conditions (see Patent Document 13) or a yarn immediately after melt spinning polyester is dipped in a crosslinking agent and drawn. However, a method for producing a crosslinked polyester fiber by irradiation with an electron beam (see Patent Document 14) is disclosed. However, these methods do not solve the phenomenon of heat melting at a temperature higher than the melting point of polyester, and do not provide heat resistance at a high temperature of 250 ° C. or higher.

  A fiber made of a copolyester having excellent dimensional stability, high strength, durability and the like used for a carcass member and a belt material is produced by a known method in the art, and Patent Document 15 is an example of a particularly preferable method. , 16 is mentioned.

JP 55-166235 A JP 54-6051 A JP-A-7-166419 JP-A-7-166420 JP 58-23916 A JP-A-5-163612 JP-A-10-168661 JP-A-10-168655 JP 2003-193331 A Japanese Patent Laid-Open No. 2-99667 JP-A-2-127562 JP-A-3-59168 Japanese Patent Laid-Open No. 7-118920 JP-A-6-248521 JP 58-98419 A JP 59-168119 A

  The object of the present invention is to impart heat resistance at a temperature higher than the melting point, which is a problem of polyester fibers, while maintaining excellent dimensional stability, high strength, and durability of polyester fibers made of copolymerized polyester, and heat melting. An object of the present invention is to obtain a polyester fiber excellent in heat resistance that can maintain its form without being formed.

As a result of intensive studies, the present inventors have impregnated a polyester unstretched yarn and / or stretched yarn obtained by melt spinning a polymer comprising a copolyester with a compound having at least two unsaturated bonds. After that, the inventors have found that the above object can be achieved by irradiating actinic rays, and have reached the present invention.

That is, the present invention is achieved by the following.
1. Heat-resistant, characterized by impregnating a polyester undrawn yarn and / or drawn yarn obtained by melt spinning a copolyester with a compound having at least two unsaturated bonds and then irradiating actinic rays Cross-linked polyester fiber.
2. 2. The heat-resistant cross-linking as described in 1 above, wherein the polyester fiber surface layer obtained by impregnation has a compound layer having at least two unsaturated bonds, and the thickness of the layer is at least 1 μm or more. Type polyester fiber.
3. At least the absorbance ratio of the absorbance of the compound and the absorbance of the polyester determined from the IR spectrum of the polyester fiber obtained by impregnation,
Polyester fiber surface layer: 0.1 or more Polyester fiber inside: 0.1 or more, The heat-resistant crosslinked polyester fiber according to 1 or 2 above.
4). A heat-resistant cross-linked polyester fiber obtained by treating a polyester fiber with a carrier agent, impregnating a compound having at least two unsaturated bonds and irradiating with actinic rays.
5. The heat-resistant crosslinked polyester fiber according to any one of 1 to 4 above, wherein the actinic ray is an electron beam or a γ-ray.

  After impregnating a polyester fiber comprising the copolymerized polyester of the present invention with a compound having at least two unsaturated bonds, a crosslinking reaction of the compound present on the surface layer of the polyester fiber by irradiation with electron beam, γ ray or the like or / In addition, the cross-linking reaction of the compound that has penetrated into the inside occurs, and at the same time, the cross-linking reaction between the compound existing in the surface layer and the compound that has penetrated into the inside also occurs, thereby suppressing the thermal melting at the melting temperature of the polyester fiber by forming a cross-linked structure. Can do.

  As a result, the feature is that the form can be maintained without causing thermal melting. What is more surprising is that the shape can be maintained even at a temperature of 300 ° C. or higher without thermal melting. The present invention is useful as a carcass member of a run-flat tire that has been difficult to use due to insufficient heat resistance, and can also be applied to impart heat resistance to nylon fibers other than fibers made of a copolyester.

Hereinafter, the present invention will be described in detail.
The present invention is a heat-resistant material that can maintain its shape without heat melting even at a high temperature, particularly at a melting point of the copolyester or higher, preferably 265 ° C. or higher, more preferably 280 ° C. or higher, more preferably 300 ° C. or higher. An improved heat-resistant cross-linked polyester fiber is provided.

  The copolyester in the present invention, particularly the aromatic copolyester, is a polycondensate of an aromatic dicarboxylic acid component and a diol component, and is not particularly limited, including known ones. Examples of aromatic dicarboxylic acid components include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyl ether dicarboxylic acid, and 5-sodium sulfone. Examples include phthalic acid. Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferred. Examples of the diol component include ethylene glycol, diethylene glycol, triethylene glycol, trimethylene glycol, tetramethylene glycol, propylene glycol, octanetylene glycol, decanmethylene glycol, and polyethylene glycol; aliphatic diols such as cyclohexanediol and cyclohexanedimethanol Alicyclic diols; aromatic diols such as naphthalenediol, bisphenol A, resorcin, and the like can be exemplified. Of these, aliphatic diols such as ethylene glycol and trimethylene glycol are preferred. In the aromatic polyester of the present invention, the aromatic dicarboxylic acid component and the diol component are each composed of a single component, and may be a copolyester composed of three or more types. Furthermore, you may blend 2 or more types of aromatic polyester resins.

  Further, in the copolymer polyester, a small amount of other optional polymers, antioxidants, radical scavengers, electrostatic agents, dyeing improvers, dyes, pigments, matting agents, fluorescent whitening agents, inert fine particles, and other Additives may be included. As a method for obtaining an aromatic polyester, it is not necessary to employ special polymerization conditions, and when a reaction product of an aromatic dicarboxylic acid component and / or an ester-forming derivative thereof and a diol component is polycondensed into a polyester. It can be synthesized by any method employed. 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 using these catalysts, 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 aromatic carboxylic acid component constituting the polyester. .

  Further, the intrinsic viscosity (IV) of the copolyester in the present invention is preferably 0.6 or more, more preferably 0.8 or more. When IV is 0.6 or less, the intended strength and elastic modulus cannot be obtained. Moreover, it is preferable that the amount of carboxy terminal groups of aromatic polyester is 50 eq / ton or less, More preferably, it is 30 eq / ton or less. When it exceeds 50 eq / ton, when it is used as a polyester tire cord, durability is deteriorated due to generation of hydrolysis by an amine compound entering from rubber, which is not preferable.

Further, in the present invention, a method can be employed in which the copolymerized polyester is used as a yarn under conventional melt spinning conditions. The taken-up yarn is temporarily wound into an undrawn yarn or drawn continuously after spinning. It can be obtained by, for example, hot drawing by a spin draw method. In general, 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 superheated roll, superheated steam, a heat plate, a heat box or the like, and is not particularly limited.
As these polyester fibers, those excellent in dimensional stability, high strength and durability manufactured for industrial materials such as a reinforcing material for rubber products such as tires can be preferably used.

  In the present invention, a compound having at least two unsaturated bonds is impregnated into the undrawn yarn and / or drawn yarn of the copolyester fiber thus obtained, and the compound exists on the surface and inside of the polyester fiber. Polyester fibers are produced batchwise or continuously.

  The compound having at least two unsaturated bonds used in the present invention is a compound capable of proceeding radical polymerization reaction by irradiation with electron beam or γ-ray, and is acryloyl group, methacryloyl group, itaconoyl group, malenoyl group, fumaroyl group. A compound having two or more unsaturated groups in one molecule consisting of a crotoyl group, an acryloylamino group, a methacryloylamino group, a cinnamoyl group, a vinyl group, an allyl group, a styryl group, and the like, and more specifically, Examples include compounds having a cyanuric acid or isocyanurate ring in one molecule and derivatives thereof, such as triallyl isocyanurate, triallyl cyanurate, diallyl methyl isocyanurate, diallyl ethyl isocyanurate, diallyl decyl isocyanurate, diallyl dodecyl iso Anurate, diallyl myristyl isocyanurate, diallyl cetyl isocyanurate, diallyl stearyl isocyanurate, ethyl bis diallyl isocyanurate, tetramethylene bis diallyl isocyanurate, hexamethylene bis diallyl isocyanurate, decamethylene bis diallyl isocyanurate, oxydiethyl bis diallyl isocyanurate , Dioxytriethylenebisdiallyl isocyanurate, diallyl methyl cyanurate, diallyl ethyl cyanurate, diallyl decyl cyanurate, xylene bis diallyl isocyanurate, 1,3-diallyl-5- (2,3-epoxypropan-1-yl ) -1,3,5-triazine-2,4,6 (1H, 3H5H) -trione, tris (2-hydroxyethyl) isocyanane Compounds such as thiotriacrylate and the like, and can be used without particular limitation as long as the compound having a cyanuric acid or isocyanurate ring in one molecule and a compound having an unsaturated group in its derivative are used. , Triallyl isocyanurate, 1,3-diallyl-5- (2,3-epoxypropan-1-yl) -1,3,5-triazine-2,4,6 (1H, 3H5H) -trione, tris ( 2-Hydroxyethyl) isocyanocyanurate triacrylate or the like can be preferably used, and two or more kinds may be mixed if necessary.

  A preferable viscosity of the compound used in the present invention can be used as long as it is in the range of 5 to 150 mPa · s at room temperature (25 ° C.), but it may be heated to such an extent that the compound does not volatilize. Furthermore, it can be preferably recommended that the temperature is increased to near the glass transition point of the aromatic copolymer polyester so that the compound is positively impregnated into the polyester fiber.

  The conditions for impregnating the polyester fiber with the above compound are not particularly limited, but it is preferable to immerse in a warm bath at 30 to 100 ° C. for about 3 to 15 minutes in order to allow the compound to penetrate into the polyester fiber. When a low viscosity compound is used at room temperature (25 ° C.), it can penetrate inside in about 3 to 5 minutes, and the compound adhering to the polyester fiber can be removed by an optional roller or guide bar. The thickness after crosslinking and curing of the polyester fiber surface layer is preferably 1 μm or more, preferably 4 μm or more. When the thickness of the surface layer is 1 μm or less, it is disadvantageous because the crosslinking density is insufficient and the heat resistance is insufficient.

  The presence of the compound contained in the polyester fiber thus obtained can be confirmed by the absorbance ratio obtained from the absorbance of the polyester and the absorbance of the compound obtained from the IR spectrum by the IR spectrum analysis measurement method. If it is 0.1 or more, a compound exists and crosslinkability is obtained. If it is 0.1 or less, sufficient crosslinkability cannot be obtained, so that the heat resistance is insufficient, which is not preferable. Usually, not only undrawn yarn but also drawn yarn has 50% or more amorphous part, so that the active impregnation of the compound into this amorphous part is the most preferable impregnation method.

  In the present invention, it is preferable to use a carrier agent in order to further improve the permeability of the compound. Specific examples of the carrier agent include carrier agents such as 1,2,4-trichlorobenzene, orthodichlorobenzene, orthophenylphenol, duphenyl, methylnaphthalene, butyl benzoate, dimethyl terephthalate, and methyl salicylate. It is preferable to treat in the previous step of impregnating the compound. The carrier agent treatment is preferably a dipping treatment or a treatment by a spraying method. In the case of a spraying treatment, the treatment is preferably performed by heating at around 100 ° C.

  In order to obtain the heat-resistant cross-linked polyester fiber of the present invention, after impregnation with a compound, actinic rays such as ultraviolet rays, electron beams, and γ rays are irradiated to generate a radical reaction and crosslink. In particular, an electron beam or γ-ray having a large irradiation energy transmission power can be preferably used. In the present invention, the irradiation energy of actinic rays is 50 to 10,000 KGy, preferably 100 to 6000 KGy, and the electron beam is irradiated for crosslinking. When the irradiation energy of the electron beam is 50 KGy or less, the crosslinking reaction does not proceed sufficiently, and irradiation with 10000 KGy or more is not preferable because the polyester may be decomposed and the strength properties may be lowered. Further, if the irradiation amount is excessive, the compound layer becomes brittle and interfacial peeling occurs, which is not preferable.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Various measuring instruments and measuring methods are shown below.
(1) Electron beam irradiation Measurement equipment Irradiator Electro curtain laboratory machine Acceleration voltage 165KV
Electron current 5mA
Measurement method A sample obtained by the immersion treatment was set on a trace and irradiated with an electron beam. In addition, the electron beam was irradiated uniformly on the front and back, and the irradiation amount was the sum of them.
(2) Dynamic viscoelasticity measuring device Equipment Rheogel-E4000 Co., Ltd. UBM Measurement condition Frequency 11Hz
Starting temperature 30 ° C
Step temperature 2 ℃
End temperature 300 ℃
Temperature increase rate 5 ℃ / min
Sample width 5mm, length 15mm
Measurement Method After setting the sample on a measuring instrument, the measurement was performed under the measurement conditions. The end of measurement was visually observed to determine whether the shape was maintained.
(3) Absorbance ratio Measuring instrument FT-IR analyzer FTS7000 manufactured by Digilab
ATR attachment Thermo Spectra-Tech
Thunderdome (IRE: Ge)
Detector DTGS, resolution 8 cm ⁻¹ integration count 128 times Infrared microscope Digilab UMA600
Measurement method The surface layer of the sample and the inside after removing the surface layer were taken out, molded on a film by applying pressure, placed on a Kbr plate, and the IR spectrum was measured by a microscopic transmission method.
From the obtained spectra, the ratio of the absorbance of 1690 cm ⁻¹ (absorption of isocyanurate ring) to the absorbance of 1720 cm ⁻¹ (PET ester bond) was determined by the following equation.
Absorbance ratio = ^1. Absorbance at 1690.sup.- ¹ cm / ^1. Absorbance at 1720.sup.- ¹ cm The respective absorbances were taken from the valley near 1880 cm.sup.- ¹ and the height from the baseline at 1640 cm.sup.- ¹ .
(4) Intrinsic viscosity The polymer was dissolved in a mixed solvent of parachlorophenol / tetrachloroethane = 3/1 at a concentration of 0.4 g / dl and measured at 30 ° C.
(5) Fineness According to the definition of JIS-L1017, the fineness was measured after being left in a room where the temperature and humidity were controlled at 20 ° C. and 65% RH for 24 hours.
(6) Strong Elongation According to the definition of JIS-L1017, after leaving in a room where temperature and humidity were controlled at 20 ° C. and 65% RH for 24 hours, the strength, breaking elongation and intermediate elongation were measured with a tensile tester.
(7) Surface layer thickness Measured using a thickness measuring machine.
The thickness of the surface layer was a value obtained by subtracting the thickness of the polyester fiber before impregnation from the thickness of the impregnated and crosslinked polyester fiber.

Example 1
A polyethylene terephthalate chip having an intrinsic viscosity (IV) of 0.95 was adjusted at a spinning temperature of 310 ° C. from a spinneret having a hole number of 336 so that the fineness would be 1440 dtex, and 70 ° C. and 1.0 m in a spinning cylinder. After the yarn cooled and solidified with a cooling air of / sec is taken up at a spinning speed of 3400 m / min, the draw ratio is 1. so that the strength continues to be 6.9 cN / dtex and the intermediate elongation is 5.5%. A polyester fiber stretched 6 times was obtained. Using this polyester fiber, it was immersed in a bath made of triallyl isocyanurate (viscosity 80 to 110 mPa · s) at room temperature for 5 minutes, then squeezed with a roller, and the required amount of the resulting triallyl isocyanurate-impregnated polyester fiber was obtained. Was placed in a tray and irradiated with an electron beam with an electron energy of 6000 KGy. It measured by each measuring method using the obtained polyester beam bridge | crosslinked polyester fiber.

(Example 2)
The treatment was carried out in the same manner as in Example 1 except that the immersion time in triallyl isocyanurate was 4 days.

(Example 3)
It processed and measured by the method similar to Example 1 except having heated and processed the bath temperature which consists of triallyl isocyanurate to 70 degreeC.

Example 4
1,3-diallyl-5- (2,3-epoxypropan-1-yl) -1,3,5-triazine-2,4,6 (1H, 3H5H) -trione (product name diallyl monoglycidyl isocyanuric acid) It measured by the method similar to Example 1 except having processed into the 70 degreeC heating bathtub which consists of.

(Example 5)
It measured by the method similar to Example 1 except having processed to the 30 degreeC heating bath which consists of tris (2-hydroxyethyl) isocyanurate triacrylate.

(Example 6)
The polyester fiber used in Example 1 was preliminarily treated with a chlorobenzene carrier carrier heated at 100 ° C. for 5 minutes, and then treated and measured in the same manner as in Example 3.

  As is clear from Table 1 and FIG. 6, the polyester fibers obtained in Examples 1 to 6 were polyester fibers that retained their shape without being melted by heat even at a high temperature of 300 ° C. and were excellent in heat resistance.

(Comparative Example 1)
The polyester fiber used in Example 1 was measured for the fiber state without compound impregnation treatment or electron beam crosslinking.

  As shown in Table 1 and FIG. 7, the polyester was melted at a melting point of 255 ° C. and did not retain its shape.

  The method for improving heat resistance by impregnating a compound having at least two unsaturated bonds of the present invention and irradiating actinic rays to cause a crosslinking reaction is not limited to fibers made of copolyester, but other natural fibers. And can be used for organic fibers. It is also expected to be used in other fields where heat resistance and dimensional stability are required, such as film and engineering plastics.

The IR spectrum data of the surface of the polyester fiber before the impregnation process used in Examples 1-6 and Comparative Example 1. IR spectrum data of the surface of the heat-resistant crosslinked polyester fiber obtained in Example 1. IR spectrum data inside the heat-resistant crosslinked polyester fiber obtained in Example 1. IR spectrum data of the surface of the heat-resistant crosslinked polyester fiber obtained in Example 2. IR spectrum data inside the heat-resistant crosslinked polyester fiber obtained in Example 2. It is the dynamic viscoelasticity of the heat-resistant crosslinked polyester fiber obtained in Example 1. It is the dynamic viscoelastic property of the polyester fiber of the comparative example 1.

Claims (5)

  Heat-resistant, characterized by impregnating a polyester undrawn yarn and / or drawn yarn obtained by melt spinning a copolyester with a compound having at least two unsaturated bonds and then irradiating actinic rays Cross-linked polyester fiber.   2. The heat resistance according to claim 1, wherein the surface layer of the polyester fiber obtained by impregnation has a layer of a compound having at least two unsaturated bonds, and the thickness of the layer is at least 1 μm or more. Cross-linked polyester fiber. At least the absorbance ratio of the absorbance of the compound and the absorbance of the polyester determined from the IR spectrum of the polyester fiber obtained by impregnation,
Polyester fiber surface layer: 0.1 or more Polyester fiber inside: 0.1 or more, The heat-resistant crosslinked polyester fiber according to claim 1 or 2.   A heat-resistant cross-linked polyester fiber obtained by treating a polyester fiber with a carrier agent, impregnating a compound having at least two unsaturated bonds and irradiating with actinic rays.   5. The heat resistant cross-linked polyester fiber according to claim 1, wherein the actinic ray is an electron beam or a gamma ray.

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