JP4214038B2 - Polyester fiber and industrial fabric - Google Patents

Description

  The present invention relates to a polyester fiber excellent in hydrolysis resistance and an industrial fabric represented by a papermaking dryer canvas comprising the same.

  Polyester fibers typified by polyethylene terephthalate are used for various purposes in addition to apparel because of their useful functionality, such as papermaking dryer canvas, belt fabrics for thermal bonding processes of nonwoven fabrics, and heat treatment furnaces. It is used as a constituent material for industrial fabrics such as inner conveyor belt fabrics.

  However, the polyester fiber has a drawback that the polyester constituting the fiber is easily hydrolyzed as compared with polyamide and polyolefin. For example, when polyester monofilament is used as a constituent material for a papermaking dryer canvas that dries paper in a high-temperature and high-humidity atmosphere for a long period of time, the polyester monofilament undergoes hydrolysis degradation during operation, and the strength of the papermaking dryer canvas Since it decreases in a short time, there is an important problem that the period of use of the paper dryer canvas is significantly limited.

  In order to solve such drawbacks, various proposals have been conventionally made. For example, polyester monofilaments (for example, polyethylene, polypropylene, polybutene, poly-4-methylpentene 1 and polyester monofilaments to which a specific amount of polyolefin such as polystyrene is added (for example, However, a monofilament obtained by this technique, for example, a monofilament made of polyethylene terephthalate to which polyethylene is added, is not yet practical because it has a very small effect of improving hydrolysis resistance. It was.

Further, a method for improving the hydrolysis resistance of polyester by adding a carbodiimide compound is also known. For example, a polyester monofilament containing a specific amount of a phosphorus atom and a specific amount of a specific monocarbodiimide compound (for example, Patent Document 2) has been proposed, but this monofilament has a problem that the hydrolysis resistance is insufficient to cope with recent high-temperature and high-speed papermaking, although the hydrolysis resistance is improved to some extent. I left it. In addition, although it is simply described that titanium oxide may be added to the polyester (which constitutes the monofilament) in the lower right column on lines 1 and 2 of page 3 of the specification of Patent Document 2, this oxidation is described. No further mention is made of titanium.
Japanese Patent Application Laid-Open No. 51-136923 (pages 1 to 5) JP 58-23916 (pages 1-7))

  An object of the present invention is to provide a polyester fiber typified by a polyester monofilament having excellent hydrolysis resistance without the above-mentioned drawbacks, and an industrial fabric typified by a paper-making dryer canvas comprising the same.

In order to achieve the object of the present invention, according to the present invention, 0.005 to 1.5% by weight of an unreacted monocarbodiimide compound and / or a polycarbodiimide compound 0.1 to 2.0 as a component other than polyester. A polyester fiber characterized by containing 0.05% to 2.5% by weight of titanium dioxide particles having an average particle size of 0.1 to 1.0 μm and containing 40% by weight and 40 to 200 ppm of sulfur atoms is provided.
[However, the polycarbodiimide compound is the sum of the unreacted carbodiimide group (D1) in the polycarbodiimide compound and the carbodiimide group (D2) in which the carboxyl terminal group and / or the hydroxyl terminal group of the polyester are partially reacted. It is an alkyl-substituted aromatic polycarbodiimide compound containing 5 to 100 carbodiimide groups in one molecule ((D1) + (D2)). ]
In the polyester fiber of the present invention,
The titanium dioxide particles contain, as components other than sulfur atoms, 1400 to 2000 ppm of phosphorus atoms, 1000 to 3000 ppm of potassium atoms, 10 to 100 ppm of sodium atoms, and 1 to 20 ppm of iron atoms, and the unreacted monocarbodiimide compound is N N′-di-2,6-diisopropylphenylcarbodiimide The polycarbodiimide compound is substituted with an isopropyl group at the 2,6-position and / or 2,4,6-position of the benzene ring bonded to the carbodiimide group. An aromatic polycarbodiimide compound having the above structure as a repeating unit, further containing 30 to 400 ppm of germanium atoms, and at least one metal atom selected from Group II, Group VII and Group VIII of the Periodic Table 5 to 100 ppm The metal atom is at least one selected from a cobalt atom, a magnesium atom and a calcium atom, and further contains 0.5 to 10% by weight of polystyrene having a syndiotactic structure. The polyester fiber is a monofilament. These are all preferable conditions, and by satisfying at least one of these conditions, it can be expected to obtain a more excellent effect.

  The industrial fabric of the present invention is characterized by using the above-described polyester fiber as a constituent material, and exhibits the best effect when it is a papermaking dryer canvas.

  As will be described below, the polyester fiber of the present invention has hydrolysis resistance superior to that of the conventional one, and is suitable for use as a constituent material for industrial fabrics, particularly as a constituent material for papermaking dryer canvas. Since it is particularly suitable, it has a high utility value in industries such as the papermaking industry.

   Hereinafter, the present invention will be specifically described.

   The polyester in the polyester fiber of the present invention comprises a dicarboxylic acid component and a glycol component. Examples of the dicarboxylic acid component include terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, 1,4-cyclohexanedicarboxylic acid, and the like. Examples of the glycol component include ethylene glycol, propylene glycol, tetramethylene glycol, and 1,4-cyclohexanedimethanol. These dicarboxylic acid components and glycol components can be used in appropriate combination. Further, a part of the dicarboxylic acid component may be replaced with adipic acid, sebacic acid, dimer acid, sulfonic acid metal salt-substituted isophthalic acid, etc., and a part of the glycol component may be diethylene glycol, neopentyl glycol, It may be replaced by 1,4-cyclohexanediol, polyalkylene glycol or the like. Furthermore, a small amount of chain branching agents such as pentaerythritol, trimethylolpropane, trimellitic acid, trimesic acid and boric acid can be used in combination. The polyester includes aliphatic polyesters such as polylactic acid, polybutylene succinate adipate, polyethylene succinate and polycaprolactone.

  Among these, it is most preferable to use polyethylene terephthalate (hereinafter referred to as PET) in which 90 mol% or more of the dicarboxylic acid component is made of terephthalic acid and 90 mol% or more of the glycol component is made of ethylene glycol.

  The intrinsic viscosity of the polyester used in the present invention is usually 0.5 or more, but 0.7 or more is more preferable because of excellent strength. Here, the intrinsic viscosity is an intrinsic viscosity determined from a viscosity measured at 25 ° C. in an o-chlorophenol solution, and is a value represented by [η].

  In particular, the polyester constituting the polyester monofilament is preferably one obtained by performing solid phase polycondensation subsequent to melt polycondensation. Performing solid-phase polymerization is preferable because the concentration of carboxyl end groups (hereinafter referred to as COOH end groups) can be reduced along with the increase in the molecular weight of polyester.

The polyester fiber of the present invention contains 0.005 to 1.5% by weight of an unreacted monocarbodiimide compound and / or 0.1 to 2.0% by weight of a polycarbodiimide compound.
[However, the polycarbodiimide compound is the sum of the unreacted carbodiimide group (D1) in the polycarbodiimide compound and the carbodiimide group (D2) in which the carboxyl terminal group and / or the hydroxyl terminal group of the polyester are partially reacted. It is an alkyl-substituted aromatic polycarbodiimide compound containing 5 to 100 carbodiimide groups in one molecule ((D1) + (D2)). ]
The content of the unreacted monocarbodiimide compound is more preferably in the range of 0.01 to 1.0% by weight, and still more preferably in the range of 0.03 to 0.8% by weight. Further, the content of the polycarbodiimide compound is more preferably in the range of 0.15 to 1.5% by weight, and further preferably in the range of 0.2 to 1.2% by weight.

  The polyester fiber of the present invention does not contain a polycarbodiimide compound, contains only a monocarbodiimide compound in an amount of less than 0.005% by weight, and does not contain a monocarbodiimide compound, and only 0.1% by weight of a polycarbodiimide compound. Even if it contains less than%, hydrolysis resistance becomes insufficient, which is not preferable. In addition, when the polyester fiber of the present invention contains more than 1.5% by weight of a monocarbodiimide compound or more than 2.0% by weight of a polycarbodiimide compound, melt spinning may become unstable. The resulting polyester fibers, particularly monofilaments, are not preferred because of insufficient strength.

  The unreacted monocarbodiimide compound (hereinafter referred to as MCD compound or MCD) contained in the polyester fiber of the present invention is an active compound containing one carbodiimide group (—N═C═N—) in the molecule. .

 Examples of the unreacted MCD compound include N, N′-di-o-triylcarbodiimide, N, N′-diphenylcarbodiimide, N, N′-dioctyldecylcarbodiimide, N, N′-di-2,6. -Dimethylphenylcarbodiimide, N-triyl-N'-cyclohexylcarbodiimide, N, N'-di-2,6-diisopropylphenylcarbodiimide, N, N'-di-2,6-di-tert.-butylphenylcarbodiimide, N-triyl-N′-phenylcarbodiimide, N, N′-di-p-nitrophenylcarbodiimide, N, N′-di-p-aminophenylcarbodiimide, N, N′-di-p-hydroxyphenylcarbodiimide, N , N′-di-cyclohexylcarbodiimide and N, N′-di-p-triylcarbodiimide It is. One or two or more compounds may be arbitrarily selected from these MCD compounds and contained in the polyester fiber. From the viewpoint of stability after addition to the polyester, a compound having an aromatic skeleton is advantageous. N, N'-di-2,6-diisopropylphenylcarbodiimide, N, N'-di-2,6-di-tert.-butylphenylcarbodiimide, N, N'-di-2, 6-dimethylphenylcarbodiimide, N, N′-di-o-triylcarbodiimide and the like are more preferable, and N, N′-di-2,6-diisopropylphenylcarbodiimide (hereinafter referred to as TIC) is particularly preferable. As the TIC, commercially available products such as “STABAXOL” (registered trademark) I manufactured by Rhein Chemie or “Stabilizer” (registered trademark) 7000 manufactured by Raschig AG can be used.

  The unreacted MCD compound contained in the polyester fiber has a function of reactively blocking and inactivating the COOH end group of the polyester itself having a catalytic action for promoting the hydrolysis of the polyester.

  The COOH end groups of the polyester are generated by raw material origin, polycondensation, heat and hydrolysis during melt molding, and hydrolysis during use in a moist heat atmosphere.

  In order to suppress hydrolysis of the polyester, an MCD compound is added to the polyester before melt molding, the MCD compound reacts with the COOH end group during melting, and the COOH end group is inactivated, and in the molded product In addition, it is necessary to contain an unreacted MCD compound to inactivate COOH end groups generated by hydrolysis during use in a humid and hot atmosphere. Therefore, in order to extend the useful life of the polyester fiber, it is important that the unreacted MCD compound is left and contained in the fiber.

Here, the content of the unreacted MCD compound in the polyester fiber referred to in the present invention is measured by the following method.
(1) Weigh about 200 mg of sample into a 100 ml volumetric flask.
(2) Add 2 ml of hexafluoroisopropanol / chloroform (volume ratio 1/1) to dissolve the sample.
(3) When the sample is dissolved, add 8 ml of chloroform.
(4) Acetonitrile / chloroform (volume ratio 9/1) is gradually added to make 100 ml while polymer is precipitated.
(5) The sample solution is filtered through a disk filter having an aperture of 0.45 μm and quantitatively analyzed by HPLC. The HPLC analysis conditions are as follows.

Column: Inertsil ODS-24.6 mm × 250 mm
Mobile phase: acetonitrile / water (volume ratio 94/6)
Flow rate: 1.5 ml / min.
Sample volume: 20 μl
Detector: UV (280 nm)
Examples of the polycarbodiimide compound (hereinafter abbreviated as PCD compound) contained in the polyester fiber of the present invention include isopropyl at the 2,6-position and / or 2,4,6-position of the benzene ring bonded to the carbodiimide group. An aromatic PCD compound having a structure in which a group is substituted as a repeating unit, an aromatic PCD compound synthesized from 1,3,5-tris (1-methylethyl) -2,4-diisocyanatobenzene, 1,3, An aromatic PCD compound synthesized from a mixture of 5-tris (1-methylethyl) -2,4-diisocyanatobenzene and 2.6-diisopropylbenzene diisocyanate, 1,3,5-tris (1-methyl) Ethyl) -2,4-diisocyanatobenzene and 1,3,5-tris (isopropyl) -2,4-diisocyanatobenzene Preferred examples include aromatic PCD compounds synthesized from the body and alicyclic PCD compounds synthesized from poly [1,1′-dicyclohexylmethane (4,4′-diisocyanate)]. However, there is no limitation to this.

  However, the PCD compound is the sum of the unreacted carbodiimide group (D1) in the PCD compound and the carbodiimide group (D2) in which the carboxyl terminal group and / or the hydroxyl terminal group of the polyester are partially reacted ((D1 ) + (D2)) and a PCD compound containing 5 to 100 carbodiimide groups in one molecule.

  Among these PCD compounds, use of an aromatic PCD compound having a repeating unit of a structure in which an isopropyl group is substituted at the 2.6-position and / or 2,4,6-position of a benzene ring bonded to a carbodiimide group is used. Particularly preferred.

  The aromatic PCD compound having a repeating unit having a structure in which an isopropyl group is substituted at the 2.6-position and / or 2,4,6-position of the benzene ring bonded to the carbodiimide group is a commercially available product, for example, average molecular weight About 3,000 "STABAXOL" (registered trademark) P (Rhein Chemie), average molecular weight of about "STABAXOL" (registered trademark) P100 (Rhein Chemie), and about 20,000 "Stabilizer" (registered trademark) 9000 (Raschig AG product) can be purchased and used.

  Moreover, as an alicyclic PCD compound synthesized from the poly [1,1′-dicyclohexylmethane (4,4′-diisocyanate)], for example, “CARBODILITE” (registered trademark) HMV-8CA ( Nisshinbo Co., Ltd. products) can be purchased and used.

  These PCD compounds are also commercially available as masterbatches previously kneaded into polyester, for example, PET masterbatches containing 15% by weight of “STABAXOL” (registered trademark) P100 having an average molecular weight of about 10,000. "Stabilizer" 9500 (registered trademark) which is a PET masterbatch containing 15% by weight of "STABAXOL" (registered trademark) KE-7646 (Rhein Chemie) and "Stabilizer" (registered trademark) 9000 having an average molecular weight of about 20,000. (Product of Raschig AG) is known.

  The polyester fiber of the present invention contains 0.05 to 2.5% by weight of titanium dioxide particles having an average particle diameter of 0.1 to 1.0 μm containing 40 to 200 ppm of sulfur atoms.

  It is more preferable that the content of sulfur atoms contained in the titanium dioxide particles is in the range of 50 to 150 ppm because the hydrolysis resistance of the polyester fiber becomes more excellent, and more preferably in the range of 60 to 120 ppm. .

  The average particle diameter of the titanium dioxide particles used in the present invention is in the range of 0.1 to 1.0 μm, and more preferably in the range of 0.15 to 0.8 μm. If the average particle diameter of the titanium dioxide particles is less than 0.1 μm, the protrusions on the fiber surface become too fine, the fibers become high in friction, and the yarn-making property tends to deteriorate. On the other hand, if the average particle size is larger than 1.0 μm, clogging of the spinning filter during melt spinning is accelerated, and contamination around the spinneret holes is increased, resulting in an increase in yarn breakage.

  The content of the titanium dioxide particles in the polyester fiber of the present invention is 0.05 to 2.5% by weight, particularly 0.1 to 1.0% by weight. If the content of titanium dioxide particles is less than 0.05%, hydrolysis resistance is insufficient, which is not preferable. On the other hand, when the amount is more than 2.5% by weight, clogging of the spinning filter during melt spinning is accelerated and the melt fluidity of the polyester is lowered, which is not preferable.

  When the titanium dioxide particles contain 1400 to 2000 ppm phosphorus atoms, 1000 to 3000 ppm potassium atoms, 10 to 100 ppm sodium atoms, and 1 to 20 ppm iron atoms as components other than sulfur atoms, the hydrolysis resistance is further improved. This is preferable. Moreover, it is more preferable to contain 1450-1800 ppm of phosphorus atoms, 1300-2600 ppm of potassium atoms, 15-70 ppm of sodium atoms, and 3-16 ppm of iron atoms.

  Titanium dioxide particles are commercially available from Fuji Titanium Industry Co., Ltd. or Titanium Industry Co., Ltd., and can be purchased and used.

  When the polyester fiber of the present invention contains 5 to 100 ppm of at least one metal atom selected from Group II, Group VII and Group VIII of the Periodic Table, the hydrolysis resistance of the polyester fiber is increased. It is preferable because it becomes even better. More preferably, the metal atom content is in the range of 10 to 50 ppm.

  When the content of at least one metal atom selected from Group II, Group VII and Group VIII of the periodic table is outside the above range, the hydrolysis resistance cannot be sufficiently increased. There is a tendency.

  Examples of at least one metal atom selected from Group II, Group VII, and Group VIII of the Periodic Table include magnesium, calcium, strontium, barium, manganese, iron, cobalt, and nickel. it can.

  Among these, at least one selected from a cobalt atom, a magnesium atom and a calcium atom is more preferable, and a cobalt atom is particularly preferable.

  The additive for containing at least one metal atom in the polyester may be any of chloride, oxide, acetate, nitrate, sulfate, etc., but it may be added to the polyester as acetate. preferable.

  When the polyester fiber of the present invention contains 0.5 to 10% by weight, particularly 1.0 to 8.0% by weight, of polystyrene having a syndiotactic structure, the hydrolysis resistance is further improved. This is preferable. The reason for this is that since the solubility of the MCD compound is overwhelmingly higher in the polystyrene with syndiotactic structure than the polyester, the polyester contains 0.5 to 10% by weight of polystyrene with syndiotactic structure. The added MCD compound dissolves more in the syndiotactic polystyrene during melt-kneading, and side reactions between the hydroxyl end groups of the polyester and the MCD compound are suppressed and protected. This is considered to be caused by the increase in the content of the reactive MCD compound. In addition, syndiotactic polystyrene is suitable because it is crystalline and has a high melting point of about 270 ° C. and excellent heat resistance, and does not impair the heat resistance of the fiber.

  When the content of the polystyrene having a syndiotactic structure is less than 0.5% by weight, the effect of improving hydrolysis resistance is insufficient. When the content is more than 10% by weight, it becomes difficult to produce the fiber or the fiber is obtained. Tend to be insufficient in strength.

  Also, in place of or in addition to syndiotactic polystyrene, for example, various styrene polymers (including p-methylstyrene copolymer) with isotactic and atactic structures, polyethylene Polyolefins such as polypropylene, polymethylpentenes, copolymers of ethylene and acrylates, and the like.

  The polyester fiber of the present invention includes various inorganic particles such as silicon oxide, calcium carbonate, silicon nitride, clay, talc, kaolin, and carbon black depending on the purpose, particles such as crosslinked polymer particles, various metal particles, Contains conventionally known sequestering agents, ion exchangers, anti-coloring agents, light resistance agents, inclusion compounds, antistatic agents, various colorants, waxes, silicone oils, fluororesins, and various surfactants. be able to.

  The shape of the polyester fiber of the present invention is arbitrary such as monofilament, multifilament, short fiber, and non-woven fabric. When the polyester fiber is a constituent material of industrial fabric, it is preferably a monofilament.

  The polyester monofilament of the present invention is a continuous yarn composed of one single yarn. This polyester monofilament has a cross-sectional shape perpendicular to the fiber axis direction (hereinafter referred to as a cross-sectional shape or a cross-section) that is a circle, flat, square, half moon, triangle, five or more polygons, multi-leaf shape, dog bone shape, collar It may have any cross-sectional shape such as a mold. When the polyester monofilament of the present invention is used as a constituent material for industrial fabrics, the cross-sectional shape of the monofilament is preferably a circle or a flat shape. In particular, when the monofilament is a warp of a papermaking dryer canvas, a monofilament having a flat cross-sectional shape is preferably used from the viewpoint of effectively expressing antifouling properties and the flatness of the canvas. The flat in the present invention means an ellipse, a square or a rectangle. In addition to an exact ellipse, a square or a rectangle defined mathematically, a shape substantially similar to an ellipse, a square or a rectangle, for example, a square and a rectangle. Includes shapes with rounded corners. In the case of an ellipse, the length of the major axis (LD) and the length of the minor axis (SD) intersecting at right angles at the center of the ellipse satisfy the following formula. It is preferable that the long side length (LD) and the short side length (SD) of the rectangle satisfy the following expression.

1.0 ≦ LD / SD ≦ 10
The length of the line segment passing through the center of gravity of the monofilament cross section can be appropriately selected depending on the application, but a range of 0.05 to 2.5 mm is preferable. Further, the required strength of the yarn varies depending on the use, but is preferably approximately 2 cN / dtex or more.

  The polyester fiber of the present invention is produced by melt spinning the polyester obtained by polycondensation.

  Polyester polycondensation is a method of obtaining a diglycol ester of a dicarboxylic acid by transesterification of a dialkyl ester of a dicarboxylic acid and a glycol, followed by polycondensation (hereinafter referred to as EI polymerization method), or dicarboxylic acid and glycol. For example, a method of directly polycondensation with a polymer (hereinafter referred to as a direct polymerization method) can be employed.

  When the polyester in the polyester fiber of the present invention is produced by the EI polymerization method, the polyester fiber of the present invention preferably contains at least one selected from Groups II, VII and VIII of the Periodic Table In the present invention, at least one metal atom selected from Group II, Group VII and Group VIII of the periodic table is contained in the present invention because In addition, an amount necessary for the transesterification reaction is added together with dialkyl esters of dicarboxylic acid and glycols, and the transesterification reaction is performed by a conventional method, and then an antimony type typified by a known antimony trioxide Selected from germanium-based, titanium-based, aluminum-based, etc. And one polycondensation catalyst is also a titanium dioxide particles polyester fiber contains by adding a predetermined amount of polycondensation by known methods of the present invention, then it is advantageous to pelletized in a known manner. In particular, when germanium dioxide is used as the polycondensation catalyst, it is more preferable because the color tone of the obtained fiber becomes light. In this case, the concentration of germanium metal atoms in the polyester fiber is preferably 30 to 400 ppm, more preferably 100 to 300 ppm, based on the polyester.

  When the polyester is produced by a direct polymerization method, the dicarboxylic acids and glycols are esterified by a known method, and then the titanium dioxide contained in the aforementioned known polycondensation catalyst and the polyester fiber of the present invention. Add a predetermined amount of particles and, if necessary, at least one metal atom selected from Group II, Group VII and Group VIII of the Periodic Table, polycondensate by a known method, and then pelletized by a known method It is advantageous to do so.

  After drying the polyester pellets thus obtained, melt spinning is performed by a known method. The polyester before the polyester fiber is spun is added to the MCD compound, and if necessary, the PCD compound and a syndiotactic structure. Polystyrene or the like is added, melted and kneaded, spun from a spinneret hole through a metering pump and a filtration layer, and if necessary, stretched, heat-set and oiled, and the like are wound by a known method.

Since the MCD compound reacts with the COOH group at the end of the polyester molecule as described above, in order to contain a predetermined amount of unreacted MCD compound in the polyester fiber, the polyester is melt-spun. It is necessary to inactivate the retained COOH end group by some means to leave a predetermined amount of unreacted MCD compound. For this purpose, known epoxy compounds having reactivity with the COOH end groups of polyester, oxazoline compounds, etc. are added in combination to inactivate the COOH end groups, and further, unreacted MCD compounds are added and left. However, since the polyester fiber of the present invention contains 0.005 to 1.5% by weight of the unreacted MCD compound, the COOH end groups possessed until the polyester is melt-spun are inactivated. Further, it is advantageous to melt-knead and spin the polyester by adding an MCD compound in an amount such that 0.005 to 1.5% by weight of unreacted MCD compound remains in the polyester fiber. Therefore, the polyester fiber of the present invention is used in the unused state and as a constituent material of the industrial fabric immediately after processing and after a start of use, the terminal COOH group concentration of the polyester molecule is 10 equivalents / polyester fiber of 10 ⁶ g or less. It can be said that there is.

  The content of sulfur atom, phosphorus atom, potassium atom, sodium atom and iron atom of titanium dioxide contained in polyester fiber is almost the same except that polyester fiber containing titanium dioxide and titanium dioxide particles are not contained. The polyester fibers produced in the process are each dissolved in o-chlorophenol, the solution is centrifuged to remove the polyester, and the resulting titanium sediment, sulfur atom, phosphorus atom, potassium atom, sodium atom in the centrifuged sediment are obtained. And by comparing the amount of iron atoms.

  The polyester fiber of the present invention thus obtained has excellent hydrolysis resistance and is useful as a constituent material for various industrial fabrics.

  Various industrial fabrics that use the polyester monofilament of the present invention as a constituent material are those that can be used for a longer period of time than conventional ones, because hydrolysis degradation under a high humidity and high temperature atmosphere is suppressed. Useful value for use.

  The industrial fabric in the present invention is a fabric used for various industrial applications such as a transport belt fabric and a filtration fabric using the polyester monofilament of the present invention as at least a part of the weft and / or warp of the fabric. For example, textiles attached to paper machines such as paper making wires (pulp-making fabrics), paper dryers, canvases, etc., net conveyor fabrics for thermal bonding nonwoven fabric thermal bonding processes, belt fabrics for transport in heat treatment furnaces, and various filters It is a textile. Among these, it is particularly suitable for the constituent material of the papermaking dryer canvas.

  Here, the paper dryer dryer is a paper machine as a variety of fabrics such as plain weave, double weave and triple weave (including spiral fabrics in which wefts and wefts that we follow each other are joined by a spiral monofilament for warp). This fabric is used to dry paper in a dryer, and it is used over a long period of time in a high-temperature, high-humidity atmosphere, so that excellent hydrolysis resistance is required. The excellent features of the polyester fiber of the present invention are suitable applications. In addition, the papermaking wire is a fabric used in the paper winding process as various fabrics such as plain weave, double weave, and triple weave, and is used as a long mesh or a round mesh. Furthermore, the belt woven fabric for the thermal bonding process of the nonwoven fabric is a woven fabric for allowing the nonwoven fabric to pass through the furnace in order to fuse the thermal adhesive fibers such as low melting point polyethylene constituting the nonwoven fabric. Heavy woven fabrics. Moreover, the belt fabric for conveyance in a heat treatment furnace is a fabric which conveys a semi-finished product in a high temperature zone for drying, thermosetting, sterilization, cooking, etc. of various semi-finished products. Various filters are fabrics that filter high-temperature liquids, gases, powders, and the like.

  Hereinafter, the present invention will be described in detail by giving examples of polyester monofilaments and papermaking dryer canvas using the monofilaments as representatives of the polyester fibers and industrial fabrics of the present invention.

The hydrolysis resistance of the polyester monofilament and paper dryer canvas in the examples was evaluated by the following method.
<Evaluation of hydrolysis resistance of polyester fiber (monofilament)>
After placing the monofilament in a 100 liter autoclave and treating it in 121 ° C. saturated steam for 12 days, the strength of the monofilament after treatment is determined by the following monofilament tensile test, and the strength retention compared to the strength of the monofilament before treatment is obtained. It was used as a measure of hydrolysis resistance (hereinafter referred to as a strong retention after steaming). The higher the strength retention after steaming, the better the hydrolysis resistance.
<Evaluation of hydrolysis resistance of paper dryer dryer canvas>
A paper dryer canvas cut in a warp direction of 40 cm × weft direction of 20 cm was placed in a 100 liter autoclave, treated in 121 ° C. saturated steam for 12 days, and then taken out from the autoclave for the polyester monofilament in the warp direction of the paper dryer canvas. The strength was determined by a monofilament tensile test, and the strength retention compared to the strength of the monofilament in the warp direction of the paper dryer canvas before processing was used as a measure of hydrolysis resistance (hereinafter referred to as strength retention after steaming). The higher the strength retention after steaming, the better the hydrolysis resistance of the papermaking dryer canvas.
<Monofilament tensile test method>
The tensile tester (Orientec Co., Ltd. Tensilon / UTM-III-100) was used for measurement.

The raw materials used for the production of monofilaments in the examples were as follows unless otherwise specified in the examples.
1. Titanium dioxide Titanium dioxide particles containing 80 ppm sulfur atoms, 1615 ppm phosphorus atoms, 2050 ppm potassium atoms, 30 ppm sodium atoms, 7 ppm iron atoms and an average particle size of 0.5 μm (measured by LA-920 manufactured by HORIBA) Company products).
2. MCD compound “Stabilizer” (registered trademark) 7000 (product of Raschig AG), which is a TIC (hereinafter referred to as S7000).
3. PET master batch pellet containing a PCD compound An aromatic PCD compound having a repeating unit of a structure in which an isopropyl group is substituted at the 2,6-position and / or the 2,4,6-position of a benzene ring bonded to a carbodiimide group. “STABAXOL” (registered trademark) KE-7646 (product of Rhein Chemie) (hereinafter referred to as KE7646), which is a PET master batch pellet containing 15% by weight of “STABAXOL” (registered trademark) P100 having a molecular weight of approximately 10,000.
4). Polystyrene pellets with syndiotactic structure "Zarek" (registered trademark) 30A (product of Idemitsu Petrochemical Co., Ltd.) (hereinafter referred to as SPS), which is a polystyrene pellet with a syndiotactic structure.

[Examples 1 to 6, Comparative Example 1]
Polyester PET was produced by the following method.

A predetermined amount of terephthalic acid and ethylene glycol were charged into an esterification reactor, and the esterification reaction was carried out by heating with stirring according to a conventional method, and the molten esterification product was transferred to a heated polycondensation reactor. Next, phosphoric acid in an amount of 13 ppm with respect to the PET after polycondensation was added to the polycondensation reaction vessel and stirred for 8 minutes. Under stirring, germanium dioxide as a polymerization catalyst was then added to the PET after polycondensation. Cobalt acetate [Co (CH ₃ COO) ₂ .4H ₂ O)] in an amount of 220 ppm, cobalt atom, magnesium atom, calcium atom and manganese atom having a content of 30 ppm with respect to PET after polycondensation (Example) 1) Magnesium acetate [Mg (CH ₃ COO) ₂ .4H ₂ O)] (Example 2), calcium acetate [Ca (CH ₃ COO) ₂ .H ₂ O)] (Example 3) and manganese acetate [ Mn (CH ₃ COO) ₂ .4H ₂ O)] (Example 4) and the titanium dioxide particles are 0.4% by weight (hereinafter referred to as wt) with respect to PET after polycondensation. %) (Added as a 16 wt% ethylene glycol dispersion) was added to the contents of the polycondensation reaction can. The polycondensation reaction was carried out under reduced pressure and stirring while gradually raising the temperature to 278 ° C., and then discharged, cooled, cut, and dried to obtain PET pellets with [η] = 0.61. Then the PET pellets, the solid phase polymerization by a conventional method [η] = 0.91, to give a COOH terminal group concentration = 2 solid phase polymerization PET pellets equivalent / polyester fibers 10 ⁶ g.

  Subsequently, using the above solid-phase polymerization PET pellets, production of monofilaments and characteristics of the obtained monofilaments were performed by the following methods.

  The solid-phase polymerization PET pellets were continuously supplied to the single-screw extruder via the hopper of the single-screw extruder and the polymer piping under the hopper. At the same time, 1.35 wt% of the MCD compound (S7000) heated and melted at 100 ° C. with respect to the solid phase polymerization PET pellets was continuously fed into the polymer pipe at the bottom of the hopper while being measured. A melt polymer melt-kneaded for 3 minutes at about 282 ° C. in a single-screw extruder was spun from a spinneret for circular cross-section yarns through a filter layer in a spin pack via a gear pump. The spun monofilament was cooled in a 70 ° C. hot water bath, and stretched and heat-set in a total of 5.0 times in accordance with a conventional method to obtain a polyester monofilament having a diameter of 0.43 mm and a circular cross section. The composition of the obtained polyester monofilament and the evaluation results of the strength retention after steaming are shown in Table 1 (Examples 1 to 4).

  Moreover, the composition and characteristics of the monofilament obtained in the same manner as in Example 1 except that the addition of cobalt acetate in Example 1 is omitted are also shown in Table 1 (Example 5).

For comparison, the titanium dioxide particles in Example 1 (hereinafter referred to as TiO ₂ particles) were 7 ppm of sulfur atoms (hereinafter referred to as S), 1200 ppm of phosphorus atoms (hereinafter referred to as P), and potassium atoms (hereinafter referred to as K). Example 1 except that 574 ppm, sodium (hereinafter referred to as) Na atoms 13 ppm and iron atoms (hereinafter referred to as Fe) 7 ppm containing TiO ₂ particles having an average particle diameter of 0.6 μm were added and cobalt acetate was not added. The composition and properties of monofilaments obtained in the same manner are also shown in Table 1 (Comparative Example 1). Further, the composition and properties of the monofilament obtained in the same manner as in Example 4 except that the polymerization catalyst germanium dioxide in Example 4 is changed to 300 ppm of antimony trioxide are also shown in Table 1 (Example 6).

  As is clear from Table 1, it can be seen that the polyester monofilament of the present invention has hydrolysis resistance superior to that of the conventional one, and is suitable for use as a constituent material for various industrial fabrics.

[Examples 7 to 11, Comparative Example 2]
In place of S7000 which is the MCD compound in Examples 1 to 5 and Comparative Example 1, while measuring KE7646 in an amount corresponding to 0.6 wt% PCD with respect to solid-phase polymerization PET pellets, a uniaxial extruder hopper Table 1 also shows the composition and characteristics of monofilaments obtained in the same manner as in Examples 1 to 5 and Comparative Example 1, except that the uniaxial extruder was continuously supplied via the polymer pipe at the bottom of the hopper.

  As is clear from Table 1, it can be seen that the polyester monofilament of the present invention has hydrolysis resistance superior to that of the conventional one, and is suitable for use as a constituent material for various industrial fabrics.

[Examples 12 to 22, Comparative Examples 3 and 4]
The polyester monofilaments obtained in Examples 1 to 11 and Comparative Examples 1 and 2 were used for warp and weft to weave a paper-woven dryer canvas having a plain weave structure, and its hydrolysis resistance was evaluated.

  Table 2 shows the evaluation results of the strength retention of monofilaments in the vertical direction of the paper dryer canvas after steaming.

  As is apparent from the results in Table 2, the papermaking dryer canvas, which is representative of industrial fabrics using the polyester monofilament of the present invention, has hydrolysis resistance superior to that of the conventional one, and the polyester of the present invention It can be seen that the fibers have high utility value for the constituent material of the papermaking dryer canvas.

[Examples 23 to 27, Comparative Example 5]
In addition to the solid phase polymerization PET pellets in Examples 1 to 5 and Comparative Example 1 and S7000 which is an MCD compound, while weighing KE7646 in an amount corresponding to 0.6 wt% PCD with respect to the solid phase polymerization PET pellets, The composition and characteristics of the monofilaments obtained in the same manner as in Examples 1 to 5 and Comparative Example 1 except that the uniaxial extruder is continuously supplied to the uniaxial extruder via the hopper of the uniaxial extruder and the polymer pipe below the hopper. These are also shown in Table 3.

  As is apparent from Table 3, the polyester monofilament of the present invention has hydrolysis resistance superior to that of the conventional one, and is found to be suitable for use as a constituent material for various industrial fabrics.

[Examples 28 to 32, Comparative Example 6]
The polyester monofilaments obtained in Examples 23 to 27 and Comparative Example 5 were used for warp and weft to weave a paper-made dryer canvas having a plain weave structure and evaluated for hydrolysis resistance.

  Table 4 shows the evaluation results of the strength retention of the monofilament in the longitudinal direction of the paper dryer canvas after steaming.

  As is apparent from the results in Table 4, the papermaking dryer canvas, which is representative of industrial fabrics using the polyester monofilament of the present invention, has hydrolysis resistance superior to that of the conventional one, and the polyester of the present invention It can be seen that the fibers have high utility value for the constituent material of the papermaking dryer canvas.

[Examples 33 to 37 and Comparative Example 7]
Examples 23 to 27 and Examples 23 to 27 and Comparative Example 5 except that 5 parts by weight of SPS pellets were metered into the solid phase polymerized PET pellets in addition to the solid phase polymerized PET pellets KE7646 and S7000. The composition and properties of monofilaments obtained in the same manner as in Comparative Example 5 are also shown in Table 5.

  As is apparent from Table 5, the polyester monofilament of the present invention has hydrolysis resistance superior to that of the conventional one, and is found to be suitable for use as a constituent material for various industrial fabrics.

[Examples 38 to 42 and Comparative Example 8]
The polyester monofilaments obtained in Examples 33 to 37 and Comparative Example 7 were used for warp and weft to weave a paper-made dryer canvas having a plain weave structure, and the hydrolysis resistance was evaluated.

  Table 6 shows the evaluation results of the strength retention of monofilaments in the vertical direction of the paper dryer canvas after the steaming heat treatment.

  As is apparent from the results in Table 6, the papermaking dryer canvas, which is representative of industrial fabrics using the polyester monofilament of the present invention, has hydrolysis resistance superior to that of the conventional one, and the polyester of the present invention It can be seen that the fibers have high utility value for the constituent material of the papermaking dryer canvas.

  Since the polyester fiber of the present invention has excellent hydrolysis resistance, it is a fabric bonded to a paper machine such as a papermaking wire (pulp-fried fabric), a papermaking dryer canvas, and a thermal bond nonwoven fabric. It is useful as a constituent material for net conveyor fabrics for heat bonding processes, belt fabrics for transport in heat treatment furnaces, various filter fabrics, and various industrial fabrics. Various industrial fabrics made from the polyester monofilament of the present invention can be used for a longer period of time than conventional ones because hydrolysis degradation in a high humidity and high temperature atmosphere is suppressed compared to conventional ones. It becomes high industrial utility value.

Claims (11)

Mean particle size 0 containing 0.005 to 1.5% by weight of unreacted monocarbodiimide compound and / or 0.1 to 2.0% by weight of polycarbodiimide compound and 40 to 200 ppm of sulfur atoms as components other than polyester A polyester fiber characterized by containing 0.05 to 2.5% by weight of titanium dioxide particles of 1 to 1.0 μm.
[However, the polycarbodiimide compound is the sum of the unreacted carbodiimide group (D1) in the polycarbodiimide compound and the carbodiimide group (D2) in which the carboxyl terminal group and / or the hydroxyl terminal group of the polyester are partially reacted. It is an alkyl-substituted aromatic polycarbodiimide compound containing 5 to 100 carbodiimide groups in one molecule ((D1) + (D2)). ] The polyester according to claim 1, wherein the titanium dioxide particles contain, as components other than sulfur atoms, 1400 to 2000 ppm of phosphorus atoms, 1000 to 3000 ppm of potassium atoms, 10 to 100 ppm of sodium atoms, and 1 to 20 ppm of iron atoms. fiber. The polyester fiber according to claim 1 or 2, wherein the unreacted monocarbodiimide compound is N, N'-di-2,6-diisopropylphenylcarbodiimide. The polycarbodiimide compound is an aromatic polycarbodiimide compound having a structure in which an isopropyl group is substituted at the 2,6-position and / or 2,4,6-position of a benzene ring bonded to a carbodiimide group as a repeating unit. The polyester fiber according to any one of claims 1 to 3, characterized in that The polyester fiber according to any one of claims 1 to 4, further comprising 30 to 400 ppm of germanium atoms. The polyester fiber according to any one of claims 1 to 5, further comprising 5 to 100 ppm of at least one metal atom selected from Group II, Group VII and Group VIII of the Periodic Table. . The polyester fiber according to claim 6, wherein the metal atom is at least one selected from a cobalt atom, a magnesium atom and a calcium atom. The polyester fiber according to any one of claims 1 to 7, further comprising 0.5 to 10% by weight of polystyrene having a syndiotactic structure. The polyester fiber according to claim 1, wherein the polyester fiber is a monofilament. An industrial fabric comprising the polyester fiber according to any one of claims 1 to 9 as a constituent material. The industrial fabric according to claim 10, which is a papermaking dryer canvas.