JP2004256981A - Method for producing cut fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing cut fiber, capable of producing such cut fiber with good productivity that unevenness of fiber length is decreased and therefore the fiber is high-quality. <P>SOLUTION: This method for producing the cut fiber comprises supplying a twisted fiber bundle having a denier of ≥300,000 dtex in total to a cutting part composed of stationary and movable knives through one or more pairs of feed rollers and continuously cutting the bundle, wherein the twisted fiber bundle is supplied to the cutting part after an untwisted fiber bundle having the denier is furnished with a twist of 3-50 T/m, or supplied after the untwisted fiber bundle having the denier is divided into two or more parts, then each of the divided parts is furnished with the twist of 3-50 T/m, and the twisted parts are together collected again to form the twisted fiber bundle. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a method for producing a cut fiber in which fibers are cut short. More specifically, the present invention relates to a method for producing high-quality cut fibers by cutting high-strength fibers such as wholly aromatic polyamide fibers, wholly aromatic polyester fibers, and polybenzazole fibers with good process stability.

  High-strength fibers such as wholly aromatic polyamide fibers, wholly aromatic polyester fibers, and polybenzazole fibers have excellent physical and chemical properties and are industrially extremely useful fibers. Cut fibers obtained by cutting these high-strength fibers into short pieces are widely used as reinforcing materials by mixing them with resin, concrete, rubber and the like.

  Conventionally, various cutting devices have been proposed for cutting a synthetic fiber bundle. For example, a drum cutter type fiber bundle cutting in which a synthetic fiber bundle is wound on a drum having cutting blades radially implanted on the outer peripheral surface, and the fiber wound and wound on the outer peripheral surface is pressed against the cutting blade with a pressing roller to cut the fiber bundle. There has been proposed a device, a roller cutter type fiber bundle cutting device for cutting a roller around which a fiber bundle is wound by pressing the roller with a cutter roller having a plurality of cutter blades arranged on a peripheral surface.

  However, these devices are effective for cutting synthetic fibers such as polyester and nylon, but consist of high-strength fibers such as wholly aromatic polyamide fibers, wholly aromatic polyester fibers, and polybenzazole fibers. There is a major problem in cutting yarn. That is, as is clear from the fact that high-strength fibers are used as blade-proof garments and bullet-proof garments, it is extremely difficult to cut continuously and reliably with these devices. Can not be used.

  In order to solve such a problem, Japanese Patent Application Laid-Open No. H11-107053 discloses that a fiber bundle is supplied between a fixed blade and a movable blade while gripping the fiber bundle with a pair of feed rollers. An apparatus for cutting a fiber bundle while maintaining a gap of 1 to 10 mm when cutting the blade has been proposed. However, when producing cut fibers of high-strength fibers, the high-strength fibers have a high rigidity, so the convergence of the fiber bundles is poor and the binding force between the fibers is weak. In some cases, the rotation of the feed roller was not sufficiently transmitted, so that poor take-up sometimes occurred. As a result, some fibers sag before entering the feed roller or between the feed roller and the cutting portion, and are cut without entering the reverse, so that the length of the cut fiber, that is, the variation in the fiber length is large. I tended to be. In addition, the sagging fiber is wound around the feed roller or caught by other equipment such as guides, so that not only the sagging fiber is not supplied to the cutting part, but also affects other fibers and causes supply failure, Frequently, it was necessary to interrupt the production and take measures, resulting in poor production efficiency.

  In addition, the fiber bundle once gripped by the feed roller has a weak convergence force before being supplied to the cutting portion, so that the fibers do not proceed linearly to the cutting portion and the arrangement of the fibers in the fiber bundle is disturbed. There was also. In particular, when the poor take-off occurs, the convergence state of the fiber bundle is disturbed, so this phenomenon becomes more conspicuous. As a result, the variation in the fiber length becomes larger, or the fiber bundle is not supplied well to the cut portion and is caught halfway. If it is bad, there is a problem that production efficiency is further deteriorated, such as clogging.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 2001-172830 proposes a method for making fibers easier to cut by adding moisture to the fibers, and Japanese Patent Application Laid-Open No. 6-287817 discloses a method in which fibers are fed from a feed roller. There has been proposed a method of supplying a bundle of fibers to a cutter by an air flow. However, in the former method, although the productivity is improved because the service life of the blade is prolonged due to the improvement of the cutting property, no measure is taken for the sagging fiber caused by the insufficient supply of the fiber bundle. On the other hand, in the latter method, the supply of the fiber bundle from the feed roller to the cut portion is improved, but the problem caused by the sagging fiber generated before the feed roller cannot be improved at all.
JP-A-11-107053 JP 2001-172830 A JP-A-6-287817

  The present invention has been made on the background of the above-mentioned conventional technology, and an object thereof is to provide a method for stably cutting without interrupting the production and obtaining a high-quality cut fiber with less variation in fiber length with high productivity. Is to do.

  The present inventors have conducted intensive studies to achieve the above object, and as a result, if the fiber bundle is twisted before being supplied to the feed roller to increase the binding force between the fibers, the rotation of the feed roller is easily transmitted to all the fibers. It has been found that it is possible to stably supply fibers without generating sagging fibers in the fiber bundle, and as a result, it is possible to stabilize the manufacturing process and to improve the quality of the cut fibers obtained. Reached.

  Thus, according to the present invention, “When a fiber bundle having a total fineness of 300,000 dtex or more is supplied to a cutting portion including a fixed blade and a movable blade via one or more sets of feed rollers to continuously cut the fiber bundle, Applying a twist of 3 to 50 T / m to the fiber bundle, or dividing the fiber bundle into a plurality of pieces and applying a twist of 3 to 50 T / m each, and then re-bundle and supply the bundle to a feed roller. And a method for producing a cut fiber. "

  The fiber bundle used in the present invention must have a total fineness of 300,000 dtex or more, preferably 500,000 dtex or more. When the total fineness is less than 300,000 dtex, the fiber bundle becomes small, and the number of fibers that do not contact the feed roller is reduced, so that the fiber bundle can be supplied stably, and the effect of the present invention that imparts twist to the fiber bundle described below. Becomes smaller. In the case of 500,000 dtex or more, the effect of the present invention becomes larger. On the other hand, the upper limit of the total fineness does not need to be particularly limited, but if it is too large, it is necessary to make the fiber bundle thicker in the cutting direction or expand it in the horizontal direction, and the former reduces the cutting property, and the latter reduces the equipment. Since the whole becomes large-sized, it is desirable to be 10,000,000 dtex or less, especially 5,000,000 dtex or less.

  In the present invention, the above fiber bundle is supplied to a cutting portion including a fixed blade and a movable blade via a feed roller, and is continuously cut into a cut fiber. It is customary to apply a twist before supplying the ply. Twisting may be applied to the entire fiber bundle, or the fiber bundle may be divided into a plurality of parts, twisted individually, and then bundled again. In either case, the number of twists must be in the range of 3 to 50 T / m, preferably 5 to 30 T / m. In the case of dividing into plural pieces, if the number of divisions is too large, the effect of increasing the binding force between the fibers is reduced. Therefore, it is preferable that each of the divided fiber bundles is 10,000 dtex or more.

  When the number of twists is less than 3 T / m, the effect of increasing the binding force between the fibers becomes small, so that loose fibers are generated, and the production process is insufficiently stabilized. On the other hand, if it exceeds 50 T / m, the fiber is undesirably bent due to twisting, or the cut surface of the obtained cut fiber becomes acute, so that the cut fibers are easily entangled and the dispersibility is reduced.

  The method for imparting twist is not particularly limited, and may be appropriately selected from conventionally known methods. For example, twisting may be performed according to a conventional method using a ring twisting machine, a double twisting machine, an Italy twisting machine, or the like.

  The fiber bundle cutting device used in the present invention is a device that can take a fiber bundle with a feed roller, and then supply the fiber bundle to a cutting section composed of a combination of a fixed blade and a movable blade to continuously cut the fiber bundle. It is not necessary to specifically limit. For example, as disclosed in JP-A-11-107053, a cutting device having a cutting portion including a fixed blade and a movable blade that moves up and down or left and right with respect to the fixed blade, and JP-A-6-287817. A cutting device having a cutting portion composed of a combination of a fixed blade and a rotary blade, and the like can be used.

  The fiber length of the cut fiber does not need to be particularly limited. However, in the present invention, even when the fiber length is particularly short, the cutting device can cut the fiber with good process stability, so that the effect is large. However, if the length is too short, it becomes difficult to obtain a cut fiber of good quality. Therefore, the fiber length is suitably in the range of 0.5 to 10 mm, particularly in the range of 1 to 5 mm.

  Further, the fiber bundle targeted for cutting by the present invention may be made of ordinary fibers such as polyethylene terephthalate fiber, nylon 6 fiber, nylon 66 fiber, polyethylene fiber, polyvinyl alcohol fiber, etc. It is preferable to use a high-strength fiber or a high-elasticity fiber because the effect of the present invention is further enhanced. Examples thereof include wholly aromatic polyamide fibers, wholly aromatic polyester fibers, and polybenzazole fibers, and specifically, polyparaphenylene terephthalamide fibers, copolyparaphenylene-3,4'-oxydiphenylene terephthalamide. Fibers and polyparaphenylene benzoxazole fibers can be exemplified.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, each physical property value in an Example was measured by the following method.

(1) Fiber length The cut fiber (cut fiber) was arbitrarily taken out, magnified with a microscope, the length of 50 fibers was measured, and the average value was taken as the fiber length.

(2) Variation in fiber length The standard deviation value (σ) of 50 fiber lengths measured in fiber length measurement was defined as fiber length variation.

(3) Stability during production The number of times the facility was stopped in order to remove slack fibers and clogging of fibers during production of 10 kg of cut fibers was measured.

(4) Dispersibility 100 g of cut fiber was mixed with 50 liters of water and stirred for 15 minutes, and then passed through a filter having 50 slits of 0.5 mm in width and 20 mm in length. At this time, the number of fiber lumps that did not pass through the slit but were entangled and remained unraveled was measured.

[Example 1]
Twenty copolyparaphenylene / 3,4'-oxydiphenylene terephthalamide fibers (1670 dtex / 1000 filaments) were put together and twisted at 10 T / m. These were combined into 21 fiber bundles having a total fineness of about 700,000 dtex. This fiber bundle is supplied to a cutting section via a pair of feed rollers using the cutting device shown in FIG. 1, and the fiber bundle is cut at the contact point between the fixed blade 3 and the rotary blade 4 to have a target fiber length of 3.0 mm. Cut fibers were produced.

[Example 2]
In Example 1, cut fibers were produced in the same manner as in Example 1, except that 20 fibers were twisted together at 10 T / m and 90 fibers were combined to form a fiber bundle having a total fineness of about 3,000,000 dtex.

[Example 3]
A cut fiber was manufactured in the same manner as in Example 1 except that the number of twists was changed to 30 T / m.

[Example 4]
In Example 1, a cut fiber was produced in the same manner as in Example 1 except that 1,800 fibers (1670 dtex / 1000 filaments) were combined and twisted at 10 T / m to form a fiber bundle having a total fineness of about 700,000 dtex. .

[Comparative Example 1]
A cut fiber was manufactured in the same manner as in Example 1 except that the number of twists of the fiber was changed to 2 T / m.

[Comparative Example 2]
A cut fiber was manufactured in the same manner as in Example 1 except that the number of twists of the fiber was changed to 70 T / m. Table 1 summarizes the results of Examples 1 to 4 and Comparative Examples 1 and 2.

  According to the production method of the present invention, since the fiber bundle is twisted before being supplied to the feed roller to increase the binding force between the fibers, it becomes easy to transmit the rotation of the feed roller to all the fibers, Even with high-strength fibers such as polyamide fibers, wholly aromatic polyester fibers, and polybenzazole fibers, a fiber bundle can be stably supplied to a cut portion without generating sagging fibers in the fiber bundle. As a result, the fiber bundle can be cut with good process stability, and a cut fiber with good quality, particularly a cut fiber with a short fiber length can be provided. Further, the obtained cut fiber can be used as an excellent reinforcing material by mixing it with resin, concrete, rubber or the like.

It is the schematic of the cutting device used in the Example.

Explanation of reference numerals

Reference Signs List 1 fiber bundle 2 feed roller 3 fixed blade 4 rotary blade

Claims (3)

  When a fiber bundle having a total fineness of 300,000 dtex or more is supplied to a cutting portion composed of a fixed blade and a movable blade via one or more sets of feed rollers to continuously cut the fiber bundle, 3 to 50 T / m, or the fiber bundle is divided into a plurality of pieces, each of which is given a twist of 3 to 50 T / m, and then bundled again and supplied to a feed roller. .   The method for producing a cut fiber according to claim 1, wherein the fiber length of the cut fiber is 0.5 to 10 mm.   3. The method for producing a cut fiber according to claim 1, wherein the fiber is at least one kind of fiber selected from a wholly aromatic polyamide fiber, a wholly aromatic polyester fiber, and a polybenzazole fiber.

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