Wholly aromatic polyamide staple fiber aggregate and wholly aromatic polyamide spun yarn comprising the same

Abstract

To provide an aggregate of staple fibers having high bundling properties even in the case of low crimped staple fibers obtained by cutting long fibers after being used in some product or staple fibers in which a treating agent is removed and the bundling properties of the fibers with each other are lowered, and to provide a spun yarn containing the same.SOLUTION: The wholly aromatic polyamide staple fiber aggregate is composed of a low crimped wholly aromatic polyamide staple fiber coated with a surface treatment agent, wherein the surface treatment agent contains a nonionic surfactant.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aggregate of wholly aromatic polyamide staple fibers having high bundling properties, and to a wholly aromatic polyamide spun yarn containing the aggregate. [Background technology]

[0002] Spun yarns using aramid fibers, which are wholly aromatic polyamide fibers, are known to have higher strength than spun yarns made from natural fibers such as cotton and hemp, and are suitable for protective materials such as cut-resistant gloves.

[0003] Spun yarn is produced from an aggregate of staple fibers cut to an appropriate length. Therefore, spun yarn is not only produced by obtaining an aggregate of staple fibers from newly produced (virgin) filaments, but is also suitable as a method for recycling used filaments, for example, by cutting filaments that have been used in some product to obtain an aggregate of staple fibers.

[0004] A certain degree of bundling ability is required for the aggregate of staple fibers used as the raw material for spun yarn. Spun yarn is a filamentous body obtained by the physical entanglement of staple fibers. However, when used long fibers are used as the raw material, for example, some substance already attached to the raw fiber reduces the bundling ability of the fibers, or a treatment agent originally attached to the long fibers is removed during use, reducing the bundling ability and making it difficult to obtain an aggregate of staple fibers.

[0005] In addition, staple fibers used as raw materials for spun yarns are generally crimped. This is because crimping makes it easier for fibers to entangle with each other. Patent Document 1 states that a crimp number of 3 or more per inch is preferable. However, crimping causes buckling or other problems in the fibers, reducing the strength of the single fibers. A reduction in the strength of the single fibers leads to a reduction in the strength of the final spun yarn. On the other hand, fibers that are not crimped maintain their single fiber strength but are less likely to entangle with each other, which can lead to a decrease in the production efficiency of the spun yarn due to, for example, fibers slipping through during the spun yarn production process. Another problem is that the strength of the final spun yarn is reduced.

[0006] There is also a method called stretch-break spinning, in which long fibers are torn off to produce short fibers and spun into yarn. However, with this method, if the fibers are not properly aligned during the torn-off process, the quality of the resulting spun yarn will be reduced. For example, when using used long fibers as the raw material, it is difficult to align the fibers, which can result in a reduction in the strength and other qualities of the final spun yarn. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-186143 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to solve the problems of the prior art and to provide an aggregate of staple fibers with high cohesion, even if the aggregate is, for example, low-crimp staple fibers obtained by cutting long fibers after use in some product, or staple fibers whose cohesion between fibers has been reduced by removing a treatment agent, and a spun yarn containing the aggregate. [Means for solving the problem]

[0009] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by applying a specific surface treatment agent to low-crimp short fibers to control the sliver strength of the short fiber aggregate within a specific range, and have thus completed the present invention.

[0010] Thus, the following invention is provided: 1. A wholly aromatic polyamide short fiber aggregate comprising low-crimp wholly aromatic polyamide short fibers coated with a surface treatment agent, the surface treatment agent containing a nonionic surfactant; 2. The wholly aromatic polyamide short fiber aggregate according to 1 above, wherein the crimp rate of the wholly aromatic polyamide short fibers is 10% or less, or the residual crimp rate of the wholly aromatic polyamide short fibers is 10% or less. 3. The wholly aromatic polyamide short fiber aggregate according to 1 above, wherein the surface treatment agent contains α-alkyl-ω-hydroxypoly(oxyethane-1,2-diyl) or α-alkenyl-ω-hydroxypoly(oxyethane-1,2-diyl). and, 4. A wholly aromatic polyamide spun yarn comprising the wholly aromatic polyamide short fiber aggregate according to any one of items 1 to 3 above, wherein the tensile strength of the spun yarn is 4.0 cN / dtex or more. [Effects of the Invention]

[0011] According to the present invention, an aggregate of short fibers with high cohesion, even if the short fibers are low in crimp or have reduced cohesion between the fibers, and a spun yarn containing the aggregate are provided. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below.

[0013] <Fully aromatic polyamide fiber> Preferred examples of the wholly aromatic polyamide fibers used in the present invention include para-type wholly aromatic polyamide fibers, copolymerized para-type wholly aromatic polyamide fibers, and meta-type wholly aromatic polyamide fibers, and more preferably copolymerized para-type wholly aromatic polyamide fibers. Specific examples of the para-type wholly aromatic polyamide fibers include polyparaphenylene terephthalamide fibers (e.g., Twaron (registered trademark) manufactured by Teijin Aramid Co., Ltd.), copolymerized para-type wholly aromatic polyamide fibers include copolyparaphenylene-3,4-oxydiphenylene terephthalamide fibers (e.g., Technora (registered trademark) manufactured by Teijin Limited), and meta-type wholly aromatic polyamide fibers include polymetaphenylene isophthalamide fibers (e.g., Conex (registered trademark) manufactured by Teijin Limited), but are not limited to these.

[0014] <Low crimp staple fiber> The low crimp staple fiber referred to in the present invention is, for example, a staple fiber obtained by cutting a long fiber after it has been used in some product, and the crimping strength of the original fiber is reduced. Specifically, the low crimp staple fiber is a staple fiber obtained by cutting a long fiber after it has been used in some product, and ... 1015 (2010) is 10.0% or less, more preferably 1.0% or more and 5.0% or less, and even more preferably 1.0% or more and 3.0% or less.

[0015] Alternatively, preferred examples include short fibers having a residual crimp percentage measured in accordance with JIS L 1015 (2010) of 10.0% or less, more preferably 1.0% to 5.0%, and even more preferably 1.0% to 3.0%. The average fiber length of these short fibers is preferably 100 mm or less, more preferably 10 mm or more and 80 mm or less, even more preferably 30 mm or more and 60 mm or less, and most preferably 35 mm or more and 55 mm or less.

[0016] <Surface treatment agent> The short fiber aggregate of the present invention is mainly composed of low-crimp wholly aromatic polyamide short fibers coated with a surface treatment agent, and it is important that the surface treatment agent contains a nonionic surfactant.

[0017] Here, "mainly composed of" means that low-crimp wholly aromatic polyamide short fibers coated with a surface treatment agent account for 85% by mass or more of the total mass of short fibers constituting the short fiber aggregate.

[0018] The surface treatment agent contains a nonionic surfactant. Preferably, it contains α-alkyl-ω-hydroxypoly(oxyethane-1,2-diyl) or α-alkenyl-ω-hydroxypoly(oxyethane-1,2-diyl). The inclusion of a nonionic surfactant improves the sizing ability of even low-crimp short fibers. In particular, the use of α-alkyl-ω-hydroxypoly(oxyethane-1,2-diyl) or α-alkenyl-ω-hydroxypoly(oxyethane-1,2-diyl) contributes to improved sizing ability.

[0019] Although the mechanism is unclear, it is speculated that an interaction occurs between the ether group portion in the α-alkyl-ω-hydroxypoly(oxyethane-1,2-diyl) or α-alkenyl-ω-hydroxypoly(oxyethane-1,2-diyl) and the amide bond portion contained in the wholly aromatic polyamide, and that the interaction between the alkyl or alkenyl groups further strengthens the attraction between the fibers via the surface treatment agent.

[0020] In other words, the chemical interaction compensates for the lack of physical entanglement, making it easier to obtain an aggregate of staple fibers and a spun yarn. In addition, as a secondary effect of the improved bundling ability brought about by the use of this agent, for example, the strength of the resulting spun yarn is improved.

[0021] The amount of the surface treatment agent used in the present invention is preferably 0.01% by weight or more and 10.0% by weight or less. It is more preferably 0.1% by weight or more and 5.0% by weight or less, and even more preferably 0.1% by weight or more and 3.0% by weight or less. If the amount of the surface treatment agent is too low, the desired inter-fiber attraction will be insufficient, which is undesirable. On the other hand, if the amount of the surface treatment agent is too high, the inter-fiber attraction will be too strong, making it impossible to achieve uniform stretching during the spinning process, which may result in a deterioration in quality, which is undesirable.

[0022] The surface treatment agent can be applied by any known method, such as spray application onto the surface using a kiss roll, nozzle or spray, or dipping the fibers in the treatment agent.

[0023] <Recombined hair processing> In the present invention, the above-mentioned staple fibers are subjected to a depilling process to form a staple fiber aggregate, and the depilling process can be carried out by a known method and is not particularly limited. Note that the depilling process referred to here refers to a technique of collecting staple fibers obtained from used or unused recycled fabrics and scraps, or aggregates of staple fibers called cotton waste generated in factories, i.e., process waste, and returning them to the state of a staple fiber aggregate again, and examples thereof include a method of depilling using a depilling machine.

[0024] Specifically, the aromatic polyamide fibers coated with the surface treatment agent are preferably opened by passing them once or multiple times over the rollers of a de-pilling machine equipped with needles, pins, or wires. The de-pilling machine is preferably equipped with metal needles or pins.

[0025] <Spinning process> The spinning process can be carried out by any known method, and is not particularly limited, but may involve, for example, four steps: carding, drawing, roving, and fine spinning. The carding process is a process in which the staple fibers that have become a cotton-like material through the above-mentioned recovered fiber processing are passed through a carding machine to open them into a web (carded cotton), and multiple webs are further bundled together to be processed into a string-like fiber aggregate called a sliver.

[0026] The carding machine may be a known machine, and is not particularly limited, but examples thereof include a flat carding machine and a roller carding machine. The tensile strength of the sliver obtained through the carding process is preferably 0.3 mN / dtex or more and 10 mN / dtex or less, more preferably 0.35 mN / dtex or more and 10 mN / dtex or less, and even more preferably 0.4 mN / dtex or more and 10 mN / dtex or less.

[0027] If the tensile strength of the sliver is too low, the fibers will not pull together well, which is undesirable and can lead to yarn breakage during the spinning process. On the other hand, if the tensile strength of the sliver is too high, the friction between the fibers will be too strong, which will prevent uniform stretching during the spinning process and result in a deterioration in quality, which is also undesirable. The sliver is then stretched and twisted in three stages: the drawing process, the roving process, and the fine spinning process, to finally obtain the spun yarn.

[0028] It is essential that the spun yarn of the present invention obtained by the above method has a tensile strength of 4.0 cN / dtex or more. If the tensile strength of the spun yarn is less than 4.0 cN / dtex, when the yarn is finally made into a product, for example, when used in a protective glove, the cut resistance will be low, and a problem will arise in that protective gloves with sufficient protective performance cannot be obtained. [Example]

[0029] The present invention will be described in detail below with reference to examples and comparative examples, but the scope of the present invention is not limited to the following examples and comparative examples. The respective property values ​​in the examples were measured by the following methods.

[0030] <Short fiber bundling> The tensile strength of a sliver obtained during the spinning process was used as an index of the short fiber cohesion. A sliver is a collection of short fibers formed into a string. In other words, if the collection of short fibers is improved, the friction between the fibers will increase, and the tensile strength of the sliver will also increase. The sliver obtained in this invention was cut to a length of 1000 mm and subjected to a tensile test using a test method in accordance with JIS L 1095 (2010). A Tensilon universal material testing machine (RTF series) was used as the tensile tester to measure the tensile strength.

[0031] <Number of crimps, crimp rate and residual crimp rate> The crimp rate and residual crimp rate were measured based on JIS L 1015 (2010).

[0032] <Single fiber strength> The tensile strength of the single fiber was measured using an Instron 5565 testing machine based on JIS L 1015 (2010).

[0033] <Spun yarn tensile test> The spun yarn obtained in the present invention was cut to a length of 200 mm and subjected to a tensile test according to JIS L 1095 (2010). A Tensilon universal material testing machine (RTF series) was used as the tensile tester, and the tensile strength was measured.

[0034] <Adhesion rate of surface treatment agent> The adhesion rate was calculated from the difference in the fiber weight before and after application of the surface treatment agent.

[0035] <Average fiber length> Thirty fibers were randomly selected from the short fiber aggregate and measured in a straight state without stretching. The lengths of the 30 fibers were measured and the average value was calculated.

[0036] <Spinning process passability> When the sliver is spun by a conventional method, if spun yarn can be obtained without problems such as yarn breakage, the spinning process passability is judged to be "good." If yarn breakage or the like occurs and spun yarn cannot be obtained, this is noted.

[0037] [Example 1] Para-aramid fiber ("Technora" manufactured by Teijin Limited) was cut to an average fiber length of 38 mm to obtain staple fiber 1. This was subjected to a de-pilling process using a rotary drum de-pilling machine equipped with pins to obtain a staple fiber aggregate (de-pilling 1). The number of crimps, crimp percentage, residual crimp percentage and tensile strength of the single fibers constituting the single fiber 1 and the rolled batting 1 were measured. The results are shown in Table 1.

[0038] Next, a surface treatment agent 1 containing α-alkyl-ω-hydroxypoly(oxyethane-1,2-diyl) was prepared. This surface treatment agent 1 was sprayed onto recycled cotton 1 using a sprayer so that the amount of active ingredient was 1% by weight, thereby obtaining raw spun cotton 1. 10 kg of raw spun cotton 1 was divided into eight equal parts, each of which was passed through a flat carding machine, and the resulting eight webs were bundled together to obtain sliver 1. Sliver 1 was spun using a conventional method to obtain spun yarn 1. Spinning process passability and sliver strength of sliver 1, and the obtained spun yarn 1 The tensile strength is shown in Table 1.

[0039] [Comparative Example 1] Wool ream 1 was obtained in the same manner as in Example 1, and this wool ream 1 was divided into eight equal parts of 10 kg each, each of which was passed through a flat carding machine. The resulting eight webs were bundled together to obtain sliver 2. Sliver 2 was spun in the usual manner to obtain spun yarn 2. During this spinning process, many yarn breakages occurred due to slip-through, and the spinning process passability was poor. The tensile strength of spun yarn 2 was measured. The results are shown in Table 1.

[0040] Comparative Example 2 Short fiber 1 was obtained in the same manner as in Example 1. This was subjected to crimping processing to obtain crimped cotton 1. The number of crimps, crimp percentage, residual crimp percentage and tensile strength of the single fibers constituting the single fiber 1 and the crimped cotton 1 were measured. The results are shown in Table 1. This crimped cotton 1 was divided into eight equal parts of 10 kg each and passed through a flat carding machine. The resulting eight webs were bundled together to obtain sliver 3. Sliver 3 was spun in a conventional manner to obtain spun yarn 3. The tensile strength, crimp rate, and residual crimp rate of the single fibers constituting crimped cotton 1 were measured. The tensile strength of spun yarn 3 was also measured. The results are shown in Table 1.

[0041] Comparative Example 3 Short fibers 1 were obtained in the same manner as in Example 1. This Staple Fiber 1 was divided into eight equal parts weighing 10 kg, and each part was passed through a flat carding machine. No entanglement of the fibers occurred, and neither a sliver nor a spun yarn was obtained. The number of crimps, crimp percentage, residual crimp percentage, and tensile strength of the single fibers constituting this Staple Fiber 1 were measured. The results are shown in Table 1.

[0042] [Table 1] [Industrial Applicability]

[0043] According to the present invention, it is possible to provide an aggregate of highly cohesive short fibers and a spun yarn containing the same, even if the aggregate is made from, for example, low-crimp short fibers obtained by cutting long fibers after use in some product, or short fibers whose cohesiveness between fibers has been reduced by removing a treatment agent, and therefore the present invention has high industrial applicability and extremely great industrial value.

Claims

1. A wholly aromatic polyamide short fiber aggregate comprising low-crimp wholly aromatic polyamide short fibers coated with a surface treatment agent, the surface treatment agent containing a nonionic surfactant.

2. 2. The wholly aromatic polyamide short fiber assembly according to claim 1, wherein the wholly aromatic polyamide short fibers have a crimp percentage of 10% or less, or a residual crimp percentage of 10% or less.

3. 2. The wholly aromatic polyamide short fiber assembly according to claim 1, wherein the surface treatment agent comprises an α-alkyl-ω-hydroxypoly(oxyethane-1,2-diyl) or an α-alkenyl-ω-hydroxypoly(oxyethane-1,2-diyl).

4. A spun yarn comprising the wholly aromatic polyamide short fiber aggregate according to any one of claims 1 to 3, wherein the tensile strength of the spun yarn is 4.0 cN / dtex or more.

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