JP2023089866A - Polyamide long fiber - Google Patents

Abstract

To provide a polyamide long fiber that has less thread breakage during fiber production and is made from a raw material obtained by materially recycling a waste fishing net made of polyamide fibers, the use of the waste fishing net as the raw material contributing to the improvement of the global environment as a circular economy.SOLUTION: A polyamide long fiber is a core-sheath composite type fiber including a core and a sheath, the core containing a polyamide obtained by materially recycling a waste fishing net, the content of the materially recycled polyamide being 5 to 50 mass% of the whole of the fiber.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a polyamide long fiber, and more particularly to a polyamide long fiber having physical properties equivalent to those of conventional products even when using polyamide material-recycled from waste fishing nets made of polyamide fiber.

Polyamide fibers have been widely used as general-purpose synthetic fibers because they have excellent strength and elongation properties and wear properties, as well as being excellent in chemical resistance and heat resistance. In addition to its high durability and lightness, it is easy to dye even though it is a synthetic fiber. etc., has a wide variety of uses.

By the way, in recent years, plastic waste has caused serious damage to marine life, such as plastic waste that has flowed into the sea damaging marine organisms, and plastic waste that has become finer due to ultraviolet rays and waves, and is eaten by marine organisms by mistaking it for food. It has become. Discarded fishing nets are also included in this garbage, and if fishing nets can be reused, it will lead to the improvement of the global environment by reducing the amount of industrial waste and recycling resources.

In addition, many environmental problems, such as global warming and abnormal weather, have become apparent with the increase in the use of fossil fuels and the increase in population. Therefore, efforts to recycle plastics are being actively carried out from the viewpoint of resource circulation toward improvement of the global environment. One example is material recycling, in which used products and waste from production processes are collected, treated to make them easier to use, and then used as materials or raw materials for new products. Material recycling has the advantage that the type of resin used as the raw material is clearly defined, and a large amount of waste is stably discharged. Therefore, if fiberization is performed using a material-recycled polymer raw material, thread breakage is likely to occur during fiber production, resulting in a decrease in production efficiency.
Moreover, from the viewpoint of a circular economy, it is desirable to reuse not only fibers and polymer scraps generated during manufacturing, but also used products to create new products.

Patent Literature 1 discloses a core-sheath composite recycled polyamide staple fiber produced by using material recycled polyamide from polyamide fibers and polymer waste generated in the spinning process as a core component and virgin polymer as a sheath component.
Patent Literature 2 discloses a core-sheath composite recycled polyamide short fiber produced by using material recycled polyamide as a core component and chemically recycled polyamide as a sheath component.

Japanese Patent Application Laid-Open No. 2007-131960 JP 2009-209464 A

However, Patent Documents 1 and 2 relate to short fibers. Since the short fibers are finally cut and manufactured, even if there is some yarn breakage in the spinning process due to some impurities, it does not pose a big problem in terms of quality. However, long fibers need to be continuous in the longitudinal direction, so if yarn breakage occurs, the product cannot be produced, making it difficult to stably produce high-quality products.

It is an object of the present invention to provide a polyamide long fiber that is less likely to break during fiber production and that uses a raw material obtained by material recycling waste fishing nets made of polyamide fiber.

The present invention includes the following aspects.
[1] A core-sheath composite fiber comprising a core portion and a sheath portion, wherein the core portion contains polyamide material-recycled from waste fishing nets, wherein the content of the material-recycled polyamide is 5 relative to the entire fiber. -50% by weight polyamide long fibers.
[2] The polyamide long fiber according to [1], wherein the sheath is made of virgin polyamide.
[3] The polyamide long fiber according to [1] or [2], wherein the core-sheath ratio is core:sheath=4:1 to 1:4.
[4] The polyamide long fiber according to any one of [1] to [3], wherein the content of the material-recycled polyamide in the core is 20 to 100% by mass.
[5] The polyamide long fiber according to any one of [1] to [4], which has an L value of 40 or less.
[6] The polyamide long fiber according to any one of [1] to [5], which has 5 or more knob-shaped portions/g having a fiber width increased by 50% or more in the single fiber.
[7] The polyamide long fiber according to any one of [1] to [6], which has a single fiber fineness of 5 to 40 dtex.
[8] The polyamide long fiber according to any one of [1] to [7], which has a tensile strength of 1.5 to 5.0 cN/dtex.

According to the present invention, it is possible to provide polyamide long fibers that are less likely to break during fiber production and that use raw materials obtained by material recycling waste fishing nets made of polyamide fibers. In addition, by using waste fishing nets as raw materials, improvement of the global environment can be realized as a circular economy.

2 is an enlarged photograph of a portion of the surface of the polyamide long fiber obtained in Example 1, which has a nodular portion.

The polyamide long fiber of the present invention is a core-sheath composite fiber having a core portion and a sheath portion and containing polyamide material-recycled from waste fishing nets in the core portion, wherein the content of the material-recycled polyamide is the entire fiber. It is 5 to 50% by mass with respect to.
"Polyamide material-recycled from waste fishing nets" refers to polyamide obtained by collecting, washing, melting, and re-chipping waste fishing nets. Hereinafter, polyamide material-recycled from waste fishing nets is also referred to as "recycled polyamide A".

The recycled polyamide A used for the core in the present invention may be blended with virgin polyamide. "Virgin polyamide" means a virgin polyamide that is not a recycled polyamide, for example nylon 6, a virgin polyamide obtained by polymerizing ε-caprolactam.
The polyamide long fibers of the present invention may contain other polymers and additives other than recycled polyamide A and virgin polyamide as long as the effects are not impaired.

The content of the recycled polyamide A in the polyamide long fiber of the present invention is 5% by mass or more, preferably 15% by mass or more, and 20 % or more by mass is more preferable. The content of recycled polyamide A in the polyamide long fiber of the present invention is 50% by mass or less with respect to the entire fiber, in terms of obtaining spinning stability during fiber production and reducing variations in color tone of the fiber. 40% by mass or less is preferable, and 35% by mass or less is more preferable. The lower limit and upper limit of the content of recycled polyamide A relative to the entire fiber can be combined arbitrarily.

The content of recycled polyamide A in the core portion of the polyamide long fiber of the present invention is preferably 20% by mass or more with respect to the total mass of the core portion, in that a sufficient amount of recycled polyamide A is easily contained in the fiber. . From the viewpoint of resource circulation, the content of recycled polyamide A in the core is more preferably 50% by mass or more, more preferably 60% by mass or more, relative to the total mass of the core. The upper limit of the recycled polyamide A content in the core is not particularly limited, and can be set to 100% by mass, for example. The lower limit and upper limit of the recycled polyamide A content in the core can be arbitrarily combined, and for example, 20 to 100 mass % is preferable.

In the polyamide long fiber of the present invention, the polyamide contained in the sheath is preferably only virgin polyamide, and more preferably the sheath is made of only virgin polyamide. When virgin polyamide is used for the sheath, the impurities mixed in the recycled polyamide A of the core are wrapped in the virgin polyamide of the sheath, thereby making it easier to ensure spinning stability during fiber production. In addition, the use of virgin polyamide for the sheath facilitates color tone adjustment during dyeing and dyeing. The sheath may contain other polymers and additives as long as the effects of the present invention are not impaired.

The core-sheath ratio of the polyamide long fibers of the present invention, that is, the mass ratio of the core and the sheath, is preferably core:sheath=4:1 to 1:4, and core:sheath=1:1 to 1:2. is more preferable. If the ratio of the core portion to the sheath portion is 4 or less, that is, if the content of the core portion is 80% by mass or less, it is easy to ensure spinning stability during fiber production. If the ratio of the core portion to the sheath portion is 1/4 or more, that is, if the content of the core portion is 20% by mass or more, it is easy to incorporate a sufficient amount of recycled polyamide A into the fiber.

The L value of the polyamide long fibers of the present invention is preferably 40 or less. The L value indicates lightness, and the larger the value, the higher the lightness.
Abandoned fishing nets from which recycled polyamide A is derived have various color tones, and the color tone of chips when re-chipped is dark due to a mixture of collected abolished fishing nets. Therefore, the color tone of the polyamide long fibers is stabilized by adding a dark color pigment during melt spinning to make the L value 40 or less. Moreover, as a method for adjusting color tone, it is preferable to use an original dyeing method in which a pigment is added from the viewpoint of environmental protection. With the original dyeing method, it is possible to adjust the color tone without using a large amount of water, which is required for dyeing.

The polyamide long fiber of the present invention may have 5 or more knob-like portions/g having a fiber width increased by 50% or more in a single fiber. However, "the fiber width is thickened by 50% or more" refers to the fiber width (single fiber fineness) when viewed from the side of the portion that occupies the majority of the polyamide continuous fiber that is not the hump-like portion means that the fiber width is thickened by 50% or more. The number of knob-like portions per 1 g of fiber in the polyamide long fiber of the present invention may be 5 pieces/g or more, and may be 5 pieces/g or more and 100 pieces/g or less.

Recycled polyamide A contains impurities of about 50 to 200 μm that adhere to waste fishing nets and remain after washing. Therefore, in polyamide long fibers obtained using recycled polyamide A, such impurities enter into single fibers and are internalized as nodular portions having a fiber width of 50% or more. However, in the present invention, recycled polyamide A is used in the core of the core-sheath composite type polyamide long fiber, so even if impurities are internalized in the nodular part of the fiber, the spinning stability of the polyamide long fiber is ensured. be done. Moreover, since such impurities are located near the center of the fiber cross section, they do not pose a major problem in terms of product quality.

The monofilament fineness of the polyamide long fibers of the present invention is preferably 5 dtex or more, more preferably 10 dtex or more, in order to reduce yarn breakage during spinning due to the influence of impurities contained in recycled polyamide A. The monofilament fineness of the polyamide long fibers of the present invention is preferably 40 dtex or less, and more preferably 30 dtex or less, from the viewpoint that the feel is less likely to become hard. The lower limit and upper limit of the monofilament fineness of the polyamide long fibers can be arbitrarily combined.

From the viewpoint of spinning stability during fiber production, the total fineness of the polyamide long fibers of the present invention is preferably 50 dtex or more, more preferably 100 dtex or more. From the point of view of fiber products, the total fineness of the polyamide long fibers of the present invention is preferably 4000 dtex or less, more preferably 3000 dtex or less. The lower limit and upper limit of the total fineness of the polyamide long fibers can be arbitrarily combined, and for example, 50 to 4000 dtex is preferable, and 100 to 3000 dtex is more preferable.

The tensile strength of the polyamide long fibers of the present invention is preferably 1.5 cN/dtex or more, more preferably 2.0 cN/dtex or more, in order to prevent the fibers from breaking during the production of woven or knitted fabrics. The tensile strength of the polyamide long fiber of the present invention is preferably 5.0 cN/dtex or less, more preferably 4.5 cN/dtex or less, from the viewpoint of reducing yarn breakage during drawing. The lower limit and upper limit of the tensile strength of the polyamide long fiber can be arbitrarily combined, for example, 1.5 to 5.0 cN/dtex is preferable, and 2.0 to 4.5 cN/dtex is more preferable.
The tensile strength of polyamide long fibers is a value measured according to JIS L1013.

The elongation of the polyamide long fibers of the present invention is preferably 10% or more, more preferably 50% or more, from the viewpoint that the fibers are difficult to cut during the production of woven or knitted fabrics. From the viewpoint of imparting sufficient tensile strength to the polyamide long fibers, the elongation of the polyamide long fibers of the present invention is preferably 150% or less, more preferably 120% or less. The lower limit and upper limit of the elongation of the polyamide long fibers can be combined arbitrarily, and for example, 10 to 150% is preferable, and 50 to 120% is more preferable.
The elongation of polyamide long fibers is a value measured according to JIS L1013.

The method for producing the polyamide long fiber of the present invention is not particularly limited except that recycled polyamide A is used as the core material. For example, a method of melt extruding a material containing recycled polyamide A for forming the core and a material for forming the sheath using an extruder equipped with a spinneret can be exemplified.
The fiber after spinning may be subjected to a drawing treatment. When stretching treatment is performed, the stretching ratio can be, for example, 1.5 to 6.0 times.

As described above, the polyamide long fiber of the present invention is a core-sheath composite fiber containing recycled polyamide A in the core, and the content of recycled polyamide A is 5 to 50% by mass based on the entire fiber. . As a result, discarded fishing nets can be recycled as a material, improving the global environment as a circular economy, reducing yarn breakage during fiber production, and stably producing polyamide long fibers.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. Each evaluation item in the examples was based on the following method.

(Number of bumps)
After counting the number of bumps on the surface of the polyamide long fibers (single fibers) in the roll-wound state, the bumps on the surface of the roll were marked with a colored pen. Measure the weight (g) of the unwound fiber when the surface part of the roll is unwound until the marking disappears, and divide the number of bumps (pieces) by the weight of the fiber (g) Thus, the number of nodules per 1 g of fiber was calculated.

(total fineness, single fiber fineness)
The total fineness of polyamide long fibers was measured according to JIS L1013. The single fiber fineness of polyamide long fibers was determined by dividing the total fineness by the number of single fibers.

(tensile strength)
The tensile strength of polyamide long fibers was measured according to JIS L1013.

(elongation)
The elongation of the polyamide long fibers was measured according to JIS L1013.

(L value)
The L value of the polyamide long fiber was measured using a spectrophotometer (manufactured by Gretag, model: CE-7000A) in a card-wound state.

(Example 1)
As materials for the core of the core-sheath composite type fiber, 50% by mass of polyamide (recycled polyamide A, manufactured by Refineverse, nylon 6) recycled from waste fishing nets and 50% by mass of virgin polyamide (nylon 6 manufactured by Riho Co., Ltd.) % was used. As a material for the sheath portion of the core-sheath composite type fiber, virgin polyamide (6 nylon manufactured by Rikiho Co., Ltd.) to which 6% by mass of a red pigment masterbatch was added was used.
After melt-kneading each material with an extruder at 250°C, melt extrusion was performed at a core-sheath ratio of 1:2 at a temperature of 250°C from a spinneret with a diameter of 1.0 mm and 80 ejection holes. was taken up at a speed of 600 m/min and drawn at a draw temperature of 160° C. and a draw ratio of 2.0 to obtain a core-sheath composite type polyamide long fiber with a total fineness of 1506 dtex and 80 filaments.

(Comparative example 1)
As a material for the solid type fiber, 10% by mass of polyamide (recycled polyamide A, manufactured by Refineverse, nylon 6) recycled from waste fishing nets and 90% by mass of virgin polyamide (nylon 6 manufactured by Riho Co., Ltd.) are used. A blend was used.
After melt-kneading the material with an extruder at 250°C, melt extrusion is performed at a temperature of 250°C from a spinneret having a diameter of a discharge hole of 1.0 mm and 80 discharge holes, and the material is wound at a speed of 600 m/min. By drawing at a drawing temperature of 160° C. and a drawing ratio of 2.0, a solid polyamide long fiber with a total fineness of 1473 dtex and 80 filaments was obtained.

(Comparative example 2)
As a material for the solid type fiber, 5% by mass of polyamide (recycled polyamide A, manufactured by Refineverse, nylon 6) recycled from waste fishing nets and 95% by mass of virgin polyamide (nylon 6 manufactured by Riho Co., Ltd.) are used. A blend was used.
After melt-kneading the material with an extruder at 250°C, melt extrusion is performed at a temperature of 250°C from a spinneret having a diameter of a discharge hole of 1.0 mm and 80 discharge holes, and the material is wound at a speed of 600 m/min. Then, by drawing at a drawing temperature of 160° C. and a drawing ratio of 2.0 times, polyamide long fibers with a total fineness of 1504 dtex and 80 filaments were obtained.

Table 1 shows the physical properties of the polyamide long fibers obtained in each example. Table 1 shows the operation time for producing polyamide long fibers and the number of yarn breakages per 1 ton of fibers.
FIG. 1 is an enlarged photograph of the surface of the polyamide long fiber obtained in Example 1, which was observed with an optical microscope, showing a portion having a bump-like portion.

As shown in Table 1, in Example 1 in which recycled polyamide A was used in the core portion at an appropriate ratio, the obtained polyamide long fibers had 5 pieces/g or more of knob-shaped portions, but yarn breakage was not confirmed, and the spinning stability was excellent.
On the other hand, in Comparative Examples 1 and 2 in which solid polyamide long fibers were produced, the number of yarn breakages was large and the spinning stability was poor.

Claims (8)

A core-sheath composite fiber comprising a core portion and a sheath portion, wherein the core portion contains polyamide material-recycled from waste fishing nets, wherein the content of the material-recycled polyamide is 5 to 50 mass with respect to the entire fiber. % polyamide filament. 2. The polyamide long fiber according to claim 1, wherein the sheath is made of virgin polyamide. 3. The polyamide long fiber according to claim 1, wherein the core-sheath ratio is core:sheath=4:1 to 1:4. The polyamide long fiber according to any one of claims 1 to 3, wherein the content of the material-recycled polyamide in the core is 20 to 100% by mass. The polyamide long fiber according to any one of claims 1 to 4, which has an L value of 40 or less. 6. The polyamide long fiber according to any one of claims 1 to 5, wherein the single fiber has 5 or more nodules/g having a fiber width increased by 50% or more. The polyamide long fiber according to any one of claims 1 to 6, having a single fiber fineness of 5 to 40 dtex. The polyamide long fiber according to any one of claims 1 to 7, having a tensile strength of 1.5 to 5.0 cN/dtex.

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