JP2006257568A - Polyamide staple for industrial fabric and the resultant industrial fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide polyamide staple having a combination of excellent hydrogen peroxide resistance and high tensile strength, thus suitable as a constituent material for industrial fabrics, and to provide such an industrial fabric using the staple. <P>SOLUTION: The polyamide staple comprises a fatty acid bisamide and a specific amount of a phenolic antioxidant. The polyamide staple has the following characteristics: The strength retention percentage represented by the formula:[(A/B)×100] is ≥30%( wherein, A is the tensile strength measured after the following procedure: the staple is immersed for 24 h in an aqueous hydrogen peroxide solution 3% in concentration kept at 80°C and then washed with water and subsequently air-dried for 24 h; and B is the tensile strength prior to the immersion ) and the tensile tenacity is ≥3 cN/dtex. The industrial fabric using the staple is also provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  Polyamide staples have been widely used as a constituent material for industrial fabrics typified by papermaking press felt because they have good physical properties such as tensile strength, bending durability, and compression recovery.

  The papermaking press felt used to squeeze the paper that has been rolled up in the papermaking 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 paper press felt 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 to maintain 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.

  On the other hand, as a conventional technique related to polyamide fiber, 0.15 to 0.5 parts by weight of ethylene / bisstearyl amide was 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. Polyamide monofilament (for example, see Patent Document 1) formed by melt spinning the composition, 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. On the other hand, polyamide monofilaments obtained by melt spinning a composition to which 0.1 to 0.5 parts by weight of ethylene bisstearyl amide is added (for example, see Patent Document 2) are all flexible. The development of polyamide monofilaments for the purpose of improving tensile strength and tensile elongation. It was not intended to improve the hydrogen peroxide resistance required for polyamide staples for industrial fabrics.

  Further, 100 parts by weight of nylon 6/66 copolymer, 0.5 to 20 parts by weight of a polyamide mainly composed of aliphatic diamine, isophthalic acid and / or terephthalic acid, and the total of both as 100 parts by weight, A polyamide monofilament (see, for example, Patent Document 3 and Patent Document 4) comprising a composition containing 5 to 20 parts by weight of ε-caprolactam and 0.1 to 0.5 parts by weight of bisamide is known. The present invention relates to the development of polyamide monofilaments for the purpose of improving transparency, flexibility and wet knot strength, and was not intended to improve the hydrogen peroxide resistance required for polyamide staples for industrial fabrics.

  Furthermore, a composition comprising 100 parts by weight of a copolyamide (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 technology also relates to the development of polyamide monofilaments for the purpose of improving transparency and wet knot strength, and did not mention the hydrogen peroxide resistance required for polyamide staples for industrial fabrics. .

Therefore, when these conventional polyamide fibers are used in industrial fabrics typified by papermaking press felt, industrial fabrics that sufficiently satisfy hydrogen peroxide resistance cannot be obtained, and improvement thereof has been demanded. This is the actual situation.
JP-A-62-41315 JP 62-170515 A Japanese Patent Laid-Open No. 3-14923 JP-A-4-214408 JP 2001-316944 A

  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 represented 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 1% by weight of a fatty acid bisamide and 0.01 to 5% by weight of a phenolic antioxidant, which is kept at 80 ° C. From the tensile strength A after being immersed in hydrogen peroxide water of 3% concentration for 24 hours, further washed with water and air-dried for 24 hours, and the tensile strength B before being immersed in hydrogen peroxide water [(A / B ) × 100], and a tensile strength measured according to 8.7 of JIS L1015: 1999 is 3 cN / dtex or more. Staples are provided.

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

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

  As described below, the polyamide staples for industrial fabrics of the present invention have excellent hydrogen peroxide resistance and high tensile strength, and are used particularly for at least a part of industrial fabrics typified by papermaking press felt. In such a case, since excellent hydrogen peroxide resistance and high durability are sufficiently exhibited, it is extremely useful 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 objectives of the present invention are 0.01 to 1% by weight of fatty acid bisamide and 0. It is necessary that the staple is made of polyamide containing 01 to 5% by weight, and further, in order to be a polyamide staple for industrial fabric that is sufficiently practical as an industrial fabric, a concentration of 3% kept at 80 ° C. From the tensile strength A after being immersed in hydrogen peroxide water for 24 hours, further washed with water and air-dried for 24 hours, and the tensile strength B before being immersed in hydrogen peroxide water, the formula [(A / B) × 100] It is necessary that the strength retention expressed is 30% or more and the tensile strength measured according to 8.7 of JIS L1015: 1999 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, if the amount of the fatty acid bisamide contained in the polyamide staple for industrial fabrics is below the above range, the hydrogen peroxide resistance is insufficient, and conversely, if it exceeds the above range, the yarn production stability tends to be unstable. In addition, the tensile strength tends to decrease, 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. This is not preferable because the tensile strength tends to decrease.

  That is, an industrial fabric having excellent hydrogen peroxide resistance and high tensile strength by adding a fatty acid bisamide and a phenolic antioxidant together to polyamide and controlling the content thereof in an optimum range. Polyamide staples for use are obtained.

  The reason why the polyamide staple for industrial fabrics of the present invention has excellent hydrogen peroxide resistance and high tensile strength is not clear, but when each of fatty acid bisamide and phenolic antioxidant is contained, Almost no improvement effect on hydrogen peroxide property is observed, and if the content of either one exceeds the specified range, the tensile strength will decrease, but both should be added together to achieve a specific content. From the fact that the hydrogen peroxide resistance can be improved by this, both the fatty acid bisamide and the phenolic antioxidant cause some kind of interaction, and their synergistic effect results in a particularly excellent hydrogen peroxide resistance and high It is considered that the tensile strength is expressed.

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

  When 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.

  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. The copolymerization ratio of nylon 6/66 is that the nylon 6 component 70 to 98% by weight and the nylon 66 component 30 to 2% by weight can provide high tensile strength and good heat setting properties for industrial fabrics. To preferred.

  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 exchange agents, anti-coloring agents, light resistance agents, antistatic agents, various coloring agents, waxes, silicone oils, and the like may be added.

  The fatty acid bisamide used in the present invention refers to a compound having two amide bonds in one molecule such as saturated fatty acid bisamide, unsaturated fatty acid bisamide, and aromatic bisamide, such as methylene biscaprylic amide, methylene biscapric acid. Amide, Methylenebislauric acid amide, Methylenebismyristic acid amide, Methylenebispalmitic acid amide, Methylene bisstearic acid amide, Methylene bisisostearic acid amide, Methylene bisbehenic acid amide, Methylene bisoleic acid amide, Methylene biserucic acid Amides, ethylene biscaprylic amide, ethylene biscapric amide, ethylene bislauric acid amide, ethylene bismyristic acid amide, ethylene bispalmitic acid amide, ethylene bisstearic acid amide, ethyl Bisisostearic acid amide, ethylene bis behenic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide, butylene bis stearic acid amide, butylene bis behenic acid amide, butylene bis oleic acid amide, butylene bis erucic acid Amide, hexamethylene bis stearic acid amide, hexamethylene bis behenic acid amide, hexamethylene bis oleic acid amide, hexamethylene bis erucic acid amide, m-xylylene bis stearic acid amide, m-xylylene bis-12-hydroxy stearic acid Amides, p-xylylene bis-stearic acid amide, p-phenylene bis-stearic acid amide, N, N'-distearyl adipic acid amide, N, N'-distearyl sebacic acid amide, N, N'-dioleyl adipic acid A N, N′-dioleyl sebacic acid amide, N, N′-distearyl isophthalic acid amide, N, N′-distearyl terephthalic acid amide, methylene bishydroxystearic acid amide, ethylene bishydroxystearic acid amide, butylene Bishydroxystearic acid amide, hexamethylene bishydroxystearic acid amide, and the like can be mentioned. Particularly, Armowax EBS (produced by Lion Akzo Co., Ltd.), which is ethylene bisstearic acid amide, can be easily obtained and preferably used. Can do.

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' -hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), can be easily obtained In addition, 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 the polyamide staple for industrial fabric of the present invention does not require any special method. For example, a mixture of a predetermined amount of polyamide pellets, fatty acid bisamide and phenolic antioxidant is uniaxial or biaxial extruder type. After supplying to the melt spinning machine, melt-kneading, extrude the molten polymer from the spinneret via the measuring gear pump provided at the end of the extruder-type melt spinning machine, cool it, wind it in the usual way, continue drawing, heat After fixing and obtaining a tow of several tens to several million dtex, a method of cutting the tow into a length of 10 to 50 mm with a guillotine cutter can be mentioned. Here, when obtaining the tow, a gear nip or the like may be used as necessary and crimped by a mechanical method.

  Also, polyamide pellets (hereinafter referred to as master batches) containing fatty acid bisamide and phenolic antioxidant separately in predetermined concentrations are prepared, and the masterbatch of polyamide, fatty acid bisamide and master batch of phenolic antioxidant are mixed. Create a masterbatch that contains melt-spun or fatty acid bisamide and phenolic antioxidant together at a certain concentration, mix and spin-spin the masterbatch containing polyamide, fatty acid bisamide, and phenolic antioxidant, and cool A method of producing polyamide staples for industrial fabrics by the same method as described above through stretching and heat solidification is also mentioned.

  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 staples for industrial fabrics of the present invention are used for industrial fabrics, the cross-sectional shape is preferably a circle or a triangle because the 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 for at least a part of an industrial fabric that represents papermaking press felt, excellent characteristics can be exhibited.

  Hereinafter, the present invention will be described in detail by way of examples of polyamide staples for industrial fabrics 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 intensity | strength retention (%) was calculated | required using the formula [(A / B) * 100] from each obtained tensile strength. 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 the 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., armor wax EBS of ethylene bis stearamide as fatty acid bisamide (manufactured by Lion Akzo Corporation), Further, Irganox 1098 (manufactured by Ciba Special Chemicals Co., Ltd., registered trademark) was used as a hindered phenol-based antioxidant.

  Nylon 6 chips, armo wax EBS, 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 spun with a gear pump. After passing through the filtration layer in the spin pack, the spinneret was extruded from a spinneret hole for a 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 1% by weight of fatty acid bisamide and 0.01 to 5% by weight of phenolic antioxidant retains strength after treatment with hydrogen peroxide. The rate was 30% or more, the hydrogen peroxide resistance was excellent, and the tensile strength was 3 cN / dtex or more, and the strength was high.

  On the other hand, the content of the fatty acid bisamide does not satisfy the range of 0.01 to 1% by weight and the content of the phenolic antioxidant (Comparative Example 1) and the phenolic antioxidant is in the range of 0.01 to 5% by weight. Polyamide staple that is not satisfied (Comparative Example 2) does not show a synergistic effect of improving the hydrogen peroxide resistance by the combined use of fatty acid bisamide and phenolic antioxidant, and is a polyamide that does not contain fatty acid bisamide and phenolic antioxidant. In the staple (Comparative Example 3), no effect of improving the hydrogen peroxide resistance was obtained.

[Comparative Example 4]
Polyamide staples were produced under the same conditions as in Example 1 except that the addition amount of armo wax EBS was 2% by weight and the addition amount of Irganox 1098 was 0.5% by weight. However, there was no extrusion of the polymer in the spinning machine. As a result, yarn breakage occurred frequently, and undissolved armo wax EBS was precipitated in the obtained polyamide staple, and the tensile strength was extremely lowered.

[Comparative Example 5]
Polyamide staples were produced under the same conditions as in Example 1 except that the addition amount of armo wax EBS was 0.15% by weight and the addition amount of Irganox 1098 was 8% by weight. However, there was no extrusion of the polymer in the spinning machine. As a result, yarn breakage occurred frequently, and undissolved Irganox 1098 precipitated in the obtained polyamide staple, and the tensile strength was extremely reduced.

[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, Ltd. 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, armo wax EBS, and Irganox 1098 are mixed in the ratios shown in Table 2, and then supplied to a uniaxial extruder type melt spinning machine with a diameter of 40 mm, and the melted polymer melted and kneaded at 280 ° C. is spun with a gear pump. After feeding into the pack and passing through the filtration layer in the spin 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 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, polyamide staples containing 0.01 to 1% by weight of fatty acid bisamide and 0.01 to 5% by weight of phenolic antioxidant have a strength retention of 30% or more and are resistant to excess. It was excellent in hydrogen oxide property and had a high tensile strength of 3 cN / dtex or higher. In particular, polyamide staples using a nylon 6/66 copolymer have high hydrogen peroxide resistance, and are extremely useful as polyamide staples constituting a papermaking press felt.

[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. It 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 staple of Example 4 has excellent hydrogen peroxide resistance, good durability such as staple breakage and abrasion, and the life cycle is 1.7 times that of the felt (A). It was high.

[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 felt (C) was low, and its life cycle was 62% lower than that of 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 that the durability such as staple breakage and abrasion is not sufficient, and the life cycle of the felt (A) of Comparative Example 9 is not sufficient. On the other hand, it became unusable in a short time of less than 40%.

[Comparative Example 11]
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 not sufficiently durable because of deterioration due to hydrogen peroxide and insufficient tensile strength. Cannot be used in less than 30% of the time.

  Since the polyamide staple for industrial fabrics of the present invention combines excellent hydrogen peroxide resistance and high tensile strength, when used in at least a part of industrial fabrics typified by papermaking press felt, Durability superior to conventional ones is exhibited, and it has extremely high utility value in the papermaking industry.

Claims (3)

A staple made of polyamide containing 0.01 to 1% by weight of a fatty acid bisamide and 0.01 to 5% by weight of a phenolic antioxidant, and immersed in hydrogen peroxide water having a concentration of 3% and kept at 80 ° C. for 24 hours. Further, the strength retention represented by the formula [(A / B) × 100] is 30 based on the tensile strength A after being washed with water and air-dried for 24 hours and the tensile strength B before being immersed in hydrogen peroxide water. %, And the tensile strength measured according to 8.7 of JIS L1015: 1999 is 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. The industrial fabric which used the polyamide staple for industrial fabrics of Claim 1 or 2 for at least one part.