JP4595061B2 - Polyamide staples for industrial fabrics and industrial fabrics - Google Patents

Description

  The present invention relates to a polyamide staple for industrial fabrics, which has hydrogen peroxide resistance and high tensile strength superior to conventional polyamide staples, and is useful as a constituent material for industrial fabrics represented by press felt for papermaking. The present invention relates to an industrial fabric.

  Since polyamide staples have good physical properties such as tensile strength, bending durability, and compression recovery property, they have been widely used as constituent materials for industrial fabrics such as papermaking press felt.

  The press felt for paper making used for squeezing paper that has been rolled up in the paper making process has a polyamide staple layer for industrial fabric disposed on one or both sides of a base fabric woven using polyamide monofilament for industrial fabric. The polyamide staple layer for industrial fabric is formed by entanglement and compression of polyamide staples for industrial fabric by needle punching.

  Since this press felt for papermaking is repeatedly subjected to compression, recovery and suction under high speed and high pressure conditions in practical use, excellent tensile strength and wear resistance have been required for maintaining the strength and shape of the felt.

  In recent years, in response to environmental measures, particularly dioxin measures, oxygen bleaches have been used as pulp bleaches in place of conventional chlorine bleaches. Hydrogen peroxide resistance has been strongly demanded.

  As a prior art relating to a polyamide fiber, a composition in which 0.15 to 0.5 parts by weight of ethylene / bisstearyl amide is added to 100 parts by weight in total of 85 to 97 parts by weight of polyamide and 3 to 15 parts by weight of ε-caprolactam. For a total of 100 parts by weight of a polyamide monofilament obtained by melt spinning (for example, see Patent Document 1), 85 to 96 parts by weight of polyamide, 2 to 10 parts by weight of ε-caprolactam and 2 to 10 parts by weight of a low molecular weight plasticizer, Polyamide monofilaments (for example, see Patent Document 2) obtained by melt spinning a composition to which 0.1 to 0.5 parts by weight of ethylene bisstearyl amide is added are known. The purpose is to improve strength and tensile elongation.

  Further, 100 parts by weight of a nylon 6/66 copolymer, 0.5 to 20 parts by weight of a polyamide comprising an aliphatic diamine and isophthalic acid and / or terephthalic acid, and a total of these parts as 100 parts by weight, -Polyamide monofilaments (for example, see Patent Document 3 and Patent Document 4) composed of a composition containing 5 to 20 parts by weight of caprolactam and 0.1 to 0.5 parts by weight of bisamide are known. The purpose is to improve transparency, flexibility and wet knot strength.

  Further, a composition comprising 100 parts by weight of a copolymerized polyamide (6/66 copolymer, 6/12 copolymer, 6/66/12 copolymer) and 0.02 to 0.3 parts by weight of bisamide, Furthermore, copolymerized polyamide monofilaments (see, for example, Patent Document 5) to which additives such as lubricants, heat stabilizers, ultraviolet absorbers, antistatic agents, water repellents, dyes and pigments are added as necessary are known. This technique is also aimed at improving transparency and wet knot strength.

  That is, the above prior art is mainly intended to improve the strength of polyamide monofilaments, and when these polyamide monofilaments are used as polyamide staples in industrial fabrics typified by papermaking press felts, Only an industrial fabric that does not sufficiently satisfy the hydrogen oxide property and easily breaks off staples was obtained.

  On the other hand, with respect to 100 parts by weight of a mixed polyamide containing a certain amount of polyamide, 0.001 to 0.1 parts by weight of copper compound, 0.005 to 1 part by weight of inorganic or organic halide, 0.05 hindered phenol ~ 3 parts by weight and / or 0.05 to 3 parts by weight of a hindered amine, and 0.05 to 3 parts by weight of an organic phosphorus compound and a heat-resistant polyamide resin composition and fibers (see, for example, Patent Document 6) As is known, this polyamide fiber is intended to improve heat resistance in addition to high strength and high elastic modulus.

  In addition, after the melt spinning of the polyamide fiber, the hindered amine compound, the hindered phenol compound, and the semicarbazide compound are used in the process after solidifying the spun polymer and before applying the spinning oil to the undrawn yarn and scraping it off. A method for producing a heat-resistant polyamide fiber characterized by imparting at least one of them (see, for example, Patent Document 7) is known. The purpose is to improve the heat resistance in the heat treatment process.

  Furthermore, it contains an additive (hindered phenol-based and / or hindered amine-based organic compound) having an effect of suppressing deterioration of polyamide, the total additive content is 0.001 to 1.0% by weight, and the breaking strength is 6. Polyamide fiber having 2 cN / dT or more, boiling water shrinkage of 18% or less, breaking energy of 15 mJ / dT or more, crystallinity of 35% or less, and birefringence of 0.030 to 0.045 (for example, Patent Document 8) However, this polyamide fiber is intended to improve strength, dyeability, and strength retention after heat setting.

  Furthermore, polyamide fibers containing a hindered amine-based antioxidant and a cyanoacrylate-based ultraviolet absorber (for example, see Patent Document 9 and Patent Document 10) are known. This polyamide fiber is intended to improve light resistance. Is.

  In other words, the above-mentioned prior art is mainly aimed at improving the heat resistance and light resistance of polyamide fibers, and when these polyamide fibers are used as polyamide staples in industrial fabrics represented by press felt for papermaking. Produced only an industrial fabric that did not sufficiently satisfy the hydrogen peroxide resistance and easily breaks off staples.

As described above, none of the above-mentioned conventional polyamide fibers sufficiently exhibited the hydrogen peroxide resistance and durability required for the recent industrial fabrics, and therefore the improvement thereof was strongly demanded. It was real.
JP-A-62-41315 JP 62-170515 A Japanese Patent Laid-Open No. 3-14923 JP-A-4-214408 JP 2001-316944 A JP-A-10-130497 JP 2000-328357 A JP 2002-88577 A JP 2003-239136 A Japanese Patent Application Laid-Open No. 8-222014

  The present invention has been made in order to improve the above-described problems in the prior art, and is for industrial fabrics having both hydrogen peroxide resistance and high tensile strength superior to conventional polyamide staples for industrial fabrics. An object of the present invention is to provide an industrial fabric typified by polyamide staples and a papermaking press felt using the same.

  In order to achieve the above object, according to the present invention, a staple comprising a polyamide containing 0.01 to 5% by weight of a cyanoacrylate light stabilizer and 0.01 to 5% by weight of a phenolic antioxidant, From the tensile strength A after immersion in hydrogen peroxide water with a concentration of 3% kept at 80 ° C. for 24 hours, followed by water washing and air drying for 24 hours, and the tensile strength B before immersion in hydrogen peroxide water, the formula [ (A / B) × 100] is 30% or more, and the tensile strength measured according to 8.7 of JIS L1015: 1999 is 3 cN / dtex or more. Polyamide staples for industrial fabrics are provided.

  In the polyamide staple for industrial fabric of the present invention, the polyamide is nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 6/66 copolymer, nylon 6/12 copolymer. A more preferable condition is at least one selected.

  The industrial fabric of the present invention is characterized in that the polyamide staple for industrial fabric is used at least in part.

  As will be described below, the polyamide staple for industrial fabrics of the present invention has excellent hydrogen peroxide resistance and high tensile strength, and is particularly suitable for at least a part of industrial fabrics typified by press felt for papermaking. When used, it exhibits excellent hydrogen peroxide resistance and high durability, and thus has extremely high utility value in the papermaking industry.

  Hereinafter, the present invention will be specifically described.

  Generally, the tensile strength of polyamide staples for industrial fabrics used as a constituent material of industrial fabrics is required to be 2.0 cN / dtex or more, but oxygen-based materials such as hydrogen peroxide as a pulp bleaching agent in the papermaking process. In the case of using a bleaching agent, it has been regarded as a problem that the industrial fabric is easily deteriorated by the oxygen-based bleaching agent.

  Therefore, in order to obtain polyamide staples for industrial fabrics having both excellent hydrogen peroxide resistance and high tensile strength, the purpose of the present invention is 0.01 to 5% by weight, preferably 0, of a cyanoacrylate light stabilizer. It is necessary that the staple is made of polyamide containing 0.02 to 2% by weight and phenolic antioxidant 0.01 to 5% by weight, preferably 0.02 to 3% by weight, and is sufficient as an industrial fabric. In order to be a practical polyamide staple for industrial fabrics, a tensile strength A after being immersed in hydrogen peroxide water having a concentration of 3% kept at 80 ° C. for 24 hours, washed with water and air-dried for 24 hours, The strength retention represented by the formula [(A / B) × 100] from the tensile strength B before being immersed in hydrogen oxide water is 30% or more, and JIS L1015: 1999, 8. It is necessary that the tensile strength measured according to 7 is 3 cN / dtex or more.

  If the above strength retention is less than 30%, the hydrogen peroxide resistance cannot be said to be improved compared to the conventional ones. If the tensile strength is less than 3 cN / dtex, it is used for an industrial fabric representing a papermaking press felt. In this case, staples are likely to be cut off, and sufficient durability cannot be exhibited.

  On the other hand, when the amount of the cyanoacrylate light stabilizer contained in the polyamide staple for industrial fabric is below the above range, the hydrogen peroxide resistance is insufficient, and conversely, when the amount exceeds the above range, the yarn production stability is improved. Not only becomes unstable, but the tensile strength decreases, which is not preferable.

  In addition, when the amount of the phenolic antioxidant contained in the polyamide staple for industrial fabric is below the above range, the hydrogen peroxide resistance is insufficient, and conversely, when the amount is above the above range, the spinning stability is unstable. In addition, the tensile strength decreases, which is not preferable.

  In other words, excellent addition of hydrogen peroxide resistance and high tensile strength can be achieved by adding both cyanoacrylate light stabilizers and phenolic antioxidants to polyamide and controlling their content within the optimum range. A polyamide staple for industrial fabrics is also obtained.

  Although it is not clear why the polyamide staple for industrial fabrics of the present invention has excellent hydrogen peroxide resistance and high tensile strength, a cyanoacrylate-based light stabilizer and a phenol-based antioxidant were each contained alone. In this case, the effect of improving the hydrogen peroxide resistance is hardly observed, and if the content of either one exceeds the specified range, the tensile strength decreases, but both of them have a specific content. From the fact that hydrogen peroxide resistance can be improved by the combined use, both the cyanoacrylate-based light stabilizer and the phenol-based antioxidant cause some kind of interaction, which is specifically superior due to its synergistic effect. It is considered that it exhibits hydrogen peroxide resistance and high tensile strength.

  In addition, about the evaluation method of the hydrogen peroxide resistance of the polyamide staple for industrial fabrics of the present invention, the concentration kept at 80 ° C. is the most suitable evaluation because it is close to the use condition of the press felt for papermaking. A method of immersing in 3% hydrogen peroxide solution for 24 hours, further washing with water and air-drying for 24 hours, measuring the tensile strength, and comparing with the tensile strength before immersing in hydrogen peroxide solution is adopted.

  If the strength retention after the immersion treatment with hydrogen peroxide obtained by this evaluation method is below the above range, the deterioration due to hydrogen peroxide is large, and it becomes difficult to obtain sufficient durability as a press felt for papermaking. .

  Polyamides constituting the polyamide staples for industrial fabrics of the present invention are various polyamides obtained by ring-opening polymerization of various lactams, polycondensation of various diamines and various dicarboxylic acids and polycondensation of various aminocarboxylic acids, and these Copolyamides combining polycondensation and ring-opening polymerization of, for example, nylon 6, nylon 66, nylon 610, nylon 46, nylon 612, nylon 11, nylon 12, nylon 6/12 copolymer (ε -Copolymer of caprolactam and laurolactam) and nylon 6/66 copolymer (copolymer of ε-caprolactam and hexamethylenediamine / adipic acid nylon salt) and the like. Is not to be done. Further, two or more kinds of these polyamides can be kneaded and used.

  Among the polyamides, at least one selected from nylon 6, nylon 66, nylon 612, nylon 11, nylon 12, nylon 6/12 copolymer and nylon 6/66 copolymer is an industry representative of papermaking press felt. Nylon 6/66 copolymer is preferably used because it is suitable for a fabric and a high tensile strength is easily obtained. When the nylon 6/66 copolymer ratio is in the range of 70 to 98% by weight of nylon 6 and 30 to 2% by weight of nylon 66, a high polyamide strength layer and a strong polyamide staple layer can be obtained. It is more preferable because it is easy.

  Furthermore, the polyamide used in the present invention includes various inorganic particles such as titanium oxide, silicon oxide, calcium carbonate, and carbon black, particles such as various metal particles, and conventionally known sequestering agents, depending on the purpose. , Ion exchangers, anti-coloring agents, light-proofing agents, antistatic agents, various coloring agents, waxes and silicone oils may be added.

  The cyanoacrylate light stabilizer used in the present invention is not particularly limited as long as it is a light stabilizer having a cyanoacrylate skeleton represented by the following formula. For example, ethyl-2-cyano-3,3-diphenylacrylate , 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate, 1,3-bis-{(2′-cyano-3,3-diphenylacryloyl) oxy} -2,2-bis-{(2-cyano -3 ′, 3′-diphenylacryloyl) methyl} propane and the like, and in particular, 1,3-bis-{(2′-cyano-3,3-diphenylacryloyl) oxy} -2,2-bis-{( Uvinul 3030 (registered trademark, manufactured by BSAF Japan Co., Ltd.), which is a commercial product of 2-cyano-3 ′, 3′-diphenylacryloyl) methyl} propane, is Since available, it is possible to preferably use.

In addition, as the phenolic antioxidant used in the present invention, there are hindered type, semi-hindered type, and less hindered type compounds, and in particular, -C (CH at the ortho position on both sides of the -OH group of phenol. ₃ ) It is preferable to use a hindered phenol antioxidant having two ₃ groups. Specific examples of the hindered phenol-based antioxidant include N, N′-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), octadecyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythrityl tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino ) -1,3,5-triazine, 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 3,5-di-t-butyl- 4-hydroxy Benzylphosphonate-diethyl ester, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, bis (3,5-di-t -Butyl-4-hydroxybenzylphosphonic acid ethyl) calcium, 2,6-di-t-butyl-4-ethylphenol, 2,6-di-t-butyl-P-cresol and the like. Irganox 1098 (registered trademark, manufactured by Ciba Special Chemicals Co., Ltd.), which is a commercial product of '-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), is easy Therefore, it can be preferably used.

  Antioxidants include phosphorous antioxidants such as phosphites and phosnites, sulfur antioxidants such as thioethers, and copper salts such as copper iodide and copper bromide. The use of phosphorus-based antioxidants and sulfur-based antioxidants is not improved in hydrogen peroxide resistance compared to unadded polyamide staples, while copper salts such as copper iodide and copper bromide are used. Is not preferable because the hydrogen peroxide resistance is remarkably lowered as compared with unadded polyamide staples.

  Next, the manufacturing method of the polyamide staple for industrial fabrics of the present invention will be described.

  The method for producing polyamide staples for industrial fabrics of the present invention does not require a special method. For example, a mixture of a predetermined amount of polyamide pellets, a cyanoacrylate light stabilizer and a phenolic antioxidant is uniaxially or biaxially. After supplying to the shaft extruder type melt spinning machine and melt-kneading, the molten polymer is extruded from the spinneret via a metering gear pump provided at the tip of the extruder type melt spinning machine, cooled, and wound in a normal manner. Subsequently, after stretching and heat setting to obtain a tow of several tens to several million dtex, the tow is further cut to a length of 10 to 50 mm with a guillotine cutter. Here, when obtaining the tow, a gear nip or the like may be used as necessary and crimped by a mechanical method.

  In addition, polyamide pellets (hereinafter referred to as master batches) containing cyanoacrylate light stabilizers and phenolic antioxidants separately at predetermined concentrations were prepared, and master batches of polyamide and cyanoacrylate light stabilizers and phenolic antioxidants were prepared. Mix and spin the masterbatch of the agent, or create a masterbatch containing the cyanoacrylate light stabilizer and the phenolic antioxidant together at the specified concentration, and polyamide, cyanoacrylate light stabilizer and the phenolic oxidation. There is also a method in which a masterbatch containing an inhibitor is mixed and melt-spun, cooled, stretched, and heat-solidified, and then a polyamide staple for industrial fabric is produced by the same method as described above.

  The shape of the cross section perpendicular to the fiber axis direction of the polyamide staple for industrial fabric of the present invention (hereinafter referred to as the cross sectional shape or cross section) is a circle, hollow, flat (including an ellipse or a shape close to a rectangle), square, T Examples include a shape, a Y shape, a half moon shape, a triangle shape, a polygon shape having five or more corners, a multi-leaf shape, a dog bone shape, and a saddle shape, and are not particularly limited.

  In particular, when the polyamide staple for industrial fabrics of the present invention is used for an industrial fabric, the cross-sectional shape is preferably a circle or a triangle because the polyamide staples are easily entangled in the needle punch and the single yarn is difficult to break. .

  The polyamide staples for industrial fabrics of the present invention thus obtained have excellent hydrogen peroxide resistance and high tensile strength compared to conventional polyamide staples, so that they are industrial fabrics, particularly excellent hydrogen peroxide resistance. When used in at least a part of an industrial fabric that represents a press felt for papermaking, excellent characteristics can be exhibited.

  Hereinafter, the present invention will be described in more detail with reference to examples of the polyamide staple for industrial fabric of the present invention. The characteristic values in the following examples are measured by the following methods unless otherwise specified in each example.

[Fineness]
It was measured according to a) A method of 8.5.1 of JIS L1015: 1999.

[Hydrogen peroxide resistance]
The obtained polyamide staple test piece for industrial fabric was immersed in hydrogen peroxide water of 3% concentration kept at 80 ° C. for 24 hours, further washed with water and air-dried for 24 hours. The tensile strength (N) was JIS L1015. : Measured 30 times according to 8.7 of 1999, the values were converted into the strength per unit fineness, and the average value of the tensile strength was defined as A (cN / dtex). Further, the tensile strength of the polyamide staple test piece before being immersed in hydrogen peroxide water was also measured by the same method, and the average value was defined as B (cN / dtex). And the strength retention (%) was calculated | required from each obtained tensile strength using Formula [(A / B) x100]. The higher the strength retention value, the higher the hydrogen peroxide resistance.

[Tensile strength]
In accordance with 8.7 of JIS L1015: 1999, the tensile strength (N) was measured under the conditions of a test length of 20 mm and a tensile speed of 20 mm / min. And it converted into the intensity | strength per unit fineness of a measurement sample, and calculated | required tensile strength (cN / dtex).

[Examples 1-8, Comparative Examples 1-3]
As nylon 6 resin, nylon 6 resin “Amilan” polyamide CM1021 chip (hereinafter referred to as nylon 6 chip) manufactured by Toray Industries, Inc., 1,3-bis-{(2′-cyano-3, as cyanoacrylate light stabilizer) 3-diphenylacryloyl) oxy} -2,2-bis-{(2-cyano-3 ′, 3′-diphenylacryloyl) methyl} propane, Uvinul 3030 (registered trademark, manufactured by BSAF Japan Ltd.), hinder Irganox 1098 (manufactured by Ciba Special Chemicals Co., Ltd., registered trademark) was used as a dophenol antioxidant.

  Nylon 6 chips, Uvinul 3030, and Irganox 1098 were mixed in the ratios shown in Table 1, and then supplied to a uniaxial extruder type melt spinning machine with a diameter of 40 mm, and the melt polymer melted and kneaded at 280 ° C. was fed into a spinning pack with a gear pump. After passing through the filtration layer in the spinning pack, it was extruded from the spinneret hole for the circular cross-sectional yarn, cooled, solidified and wound up.

  Next, the obtained undrawn yarn was converged, stretched 3.5 times with hot water of 85 ° C. as a 1.5 million dtex tow, and then heat-set with dry heat of 160 ° C. Furthermore, the obtained tow was cut into 40 mm with a guillotine cutter to obtain a circular cross-section polyamide staple having a single fiber of 2.5 dtex. Table 1 shows the tensile strength and hydrogen peroxide resistance test results of the obtained polyamide staples.

  As is apparent from the results in Table 1, the polyamide staple containing 0.01 to 5% by weight of cyanoacrylate light stabilizer and 0.01 to 5% by weight of phenolic antioxidant is treated with hydrogen peroxide. The subsequent strength retention was 30% or more, excellent hydrogen peroxide resistance, and high tensile strength of 3 cN / dtex or more.

  On the other hand, the content of the cyanoacrylate light stabilizer does not satisfy the range of 0.01 to 5% by weight and the content of the phenolic antioxidant (Comparative Example 1) and the phenolic antioxidant is 0.01 to 5% by weight. % Of the polyamide staple (Comparative Example 2) does not show the synergistic effect of improving the hydrogen peroxide resistance by the combined use of the cyanoacrylate light stabilizer and the phenolic antioxidant, and the cyanoacrylate light Polyamide staples (Comparative Example 3) containing no stabilizer and no phenolic antioxidant did not provide any effect of improving hydrogen peroxide resistance.

[Comparative Example 4]
Polyamide staples were produced under the same conditions as in Example 1 except that the addition amount of Uvinul 3030 was 7% by weight and the addition amount of Irganox 1098 was 0.5% by weight. However, the extrusion of the polymer became unstable in the spinning machine. As a result, not only the yarn breakage occurred frequently, but undissolved Uvinul 3030 precipitated in the obtained polyamide staple, and the tensile strength was extremely lowered as shown in Table 1.

[Comparative Example 5]
Polyamide staples were produced under the same conditions as in Example 1 except that the addition amount of Uvinul 3030 was changed to 0.5% by weight and the addition amount of Irganox 1098 was changed to 8% by weight. However, the extrusion of the polymer became unstable in the spinning machine. As a result, not only the yarn breakage occurred frequently, but undissolved irganox 1098 was precipitated in the obtained polyamide staple, and the tensile strength was extremely lowered as shown in Table 1.

[Examples 9 to 15]
Instead of nylon 6 of Example 4, “Amilan” polyamide CM3001 manufactured by Toray Industries, Inc. as nylon 66, “Amilan” polyamide CM2001 manufactured by Toray Industries, Inc. as nylon 610, and Daicel Tegusa Corporation “manufactured as“ Nylon 612 ” “Dylamide” D18, “RILSAN® B” manufactured by ATOFINA as nylon 11, “Daiamide” L1840 manufactured by Daicel Tegusa Co., Ltd. as nylon 12, “Amilan” polyamide CM6021 manufactured by Toray Industries, Ltd. as nylon 6/66 copolymer, nylon 6 / 12 CR8 manufactured by EMS Showa Denko KK was used as a copolymer.

  These polyamide chips, Uvinul 3030, and Irganox 1098 were mixed at the ratios shown in Table 2, and then supplied to a uniaxial extruder melt spinning machine with a diameter of 40 mm, and the melted polymer melted and kneaded at 280 ° C. into a spinning pack with a gear pump. After feeding and passing through the filtration layer in the spin pack, it was extruded from a spinneret hole for a circular cross-section yarn, cooled, solidified and wound up. Next, the obtained undrawn yarn was converged, stretched 3.5 times with hot water of 85 ° C. as a 1.5 million dtex tow, and then heat-set with dry heat of 160 ° C. Furthermore, the obtained tow was cut into 40 mm with a guillotine cutter to obtain a circular cross-section polyamide staple having a single fiber of 2.5 dtex. Table 2 shows the tensile strength and hydrogen peroxide resistance test results of the obtained polyamide staples.

  As is apparent from the results in Table 2, the polyamide staple containing 0.01 to 5% by weight of the cyanoacrylate light stabilizer and 0.01 to 5% by weight of the phenolic antioxidant has a strength retention of 30%. As described above, the hydrogen peroxide resistance was excellent, and the tensile strength was as high as 3 cN / dtex or more. In particular, polyamide staples using nylon 6/66 copolymer have high hydrogen peroxide resistance, and are extremely useful as polyamide staples constituting press felts for papermaking.

[Comparative Examples 6 and 7]
"Adekastab" PEP-36 (chemical name: bis (2,6-di-t-butyl-4-methylphenyl) penta manufactured by Asahi Denka Kogyo Co., Ltd., which is a phosphorus-based antioxidant, instead of Irganox 1098 Erythrolol diphosphite), and “Sumilyzer” TSP (chemical name: distearyl-3,3′-thiodipropionate) manufactured by Sumitomo Chemical Co., Ltd., which is a sulfur-based antioxidant, was used. Polyamide staples were obtained under the same conditions as in Example 4. Table 3 shows the tensile strength and hydrogen peroxide resistance test results of the obtained polyamide staples.

  Polyamide staples that use phosphorus-based antioxidants and sulfur-based antioxidants as antioxidants become unstable in the extrusion of the polymer in the spinning machine. As a result, wire diameter irregularities are observed, tensile strength and hydrogen peroxide resistance. Was low.

[Comparative Example 8]
Instead of Irganox 1098, 0.01% by weight of “TOC No. 2” (chemical name: cuprous iodide: CuI) manufactured by Nippon Chemical Industry Co., Ltd., which is a copper salt-based antioxidant, was used. Except for this, a polyamide staple was obtained under the same conditions as in Example 4. Although the obtained polyamide staple had a tensile strength of 3.9 cN / dtex, the degradation due to hydrogen peroxide was remarkable, and it was impossible to measure the tensile strength in the evaluation of hydrogen peroxide resistance.

[Example 16, comparative example 9]
The polyamide staple obtained in Comparative Example 3 was placed on both sides of a base fabric woven in a plain weave with nylon 6 monofilament and needle punched to produce felt (A) (Comparative Example 9). Similarly, felt (B) (Example 16) was prepared in the same manner as in Comparative Example 9, using the polyamide staple obtained in Example 4. This felt was put on a paper machine, used in a pulp pressing process using hydrogen peroxide as an oxygen bleach, and subjected to comparative evaluation based on the performance of the felt (A). As a result, the felt (B) woven with the polyamide staples of Example 4 is excellent in durability because it has excellent resistance to hydrogen peroxide, and there is no occurrence of staple breakage or abrasion. Its life cycle was 1.7 times higher than that of felt (A).

[Comparative Example 10]
A felt (C) was prepared in the same manner as in Comparative Example 9 except that the polyamide staple obtained in Comparative Example 1 was used, and used in the same pulp pressing step. As a result, the hydrogen peroxide resistance of the felt (C) was low, and its life cycle was 62% lower than that of the felt (B) of Example 16.

[Comparative Example 11]
A felt (D) was prepared in the same manner as in Comparative Example 9 except that the polyamide staple obtained in Comparative Example 4 was used, and used in the same pulp pressing step. As a result, although the felt (D) has high hydrogen peroxide resistance, the tensile strength is low, so the staples are likely to be cut off or worn, lack durability, and the life of the felt (A) of Comparative Example 9 Cannot be used in less than 40% of the cycle.

[Comparative Example 12]
A felt (E) was prepared in the same manner as in Comparative Example 9 except that the polyamide staple obtained in Comparative Example 6 was used, and used in the same pulp pressing step. As a result, the felt (E) is easily deteriorated by hydrogen peroxide and insufficient in tensile strength, so that the staple is likely to be cut off or worn, lacks durability, and has a life cycle of the felt (A) of Comparative Example 9. On the other hand, it became unusable in a short time of less than 30%.

  The polyamide staple for industrial fabrics of the present invention has excellent hydrogen peroxide resistance and high tensile strength, so when used in at least a part of industrial fabrics typified by papermaking press felt. As a result, hydrogen peroxide resistance and durability superior to those of the prior art are exhibited, making it extremely useful in the papermaking industry.

Claims (3)

A staple made of polyamide containing 0.01 to 5% by weight of a cyanoacrylate light stabilizer and 0.01 to 5% by weight of a phenolic antioxidant, and having a concentration of 3% hydrogen peroxide in water kept at 80 ° C. The strength represented by the formula [(A / B) × 100] from the tensile strength A after being soaked for 24 hours, further washed with water and air-dried for 24 hours, and the tensile strength B before being soaked in hydrogen peroxide water A polyamide staple for industrial fabric, having a retention of 30% or more and a tensile strength measured according to 8.7 of JIS L1015: 1999 of 3 cN / dtex or more. The polyamide is at least one selected from nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, nylon 6/66 copolymer and nylon 6/12 copolymer. The polyamide staple for industrial fabrics according to claim 1. An industrial fabric characterized in that the polyamide staple for industrial fabric according to claim 1 or 2 is used at least in part.