JP2007056402A - Polyvinylidene fluoride-based filament, and method for improving transparency of polyvinylidene fluoride-based filament in water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the transparency of a polyvinylidene fluoride-based filament in water. <P>SOLUTION: This polyvinylidene fluoride-based filament has a refractive index of ≤1.452 in a direction parallel to the filament axis of the polyvinylidene fluoride-based filament and a tensile strength of ≥800 MPa. This method for improving the transparency of the polyvinylidene fluoride-based filament in water comprises irradiating the filament 1 of raw material with laser beams to thermally soften the filament, and simultaneously drawing the softened filament to give a refractive index of ≤1.452 in a direction parallel to the filament axis of the polyvinylidene fluoride-based filament. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polyvinylidene fluoride filament, and more particularly to a method for improving the transparency of a polyvinylidene fluoride filament in water.

  Polyvinylidene fluoride filaments have properties such as little water absorption, refractive index close to water, high specific gravity, and excellent light resistance, and are used for fishing lines, fishing nets, and the like.

On the other hand, the manufacturing method of a synthetic fiber is disclosed by the conventional literature (patent documents 1-3). In this manufacturing method, the filament is stretched while irradiating the raw material filament with laser light.
Japanese Patent Laid-Open No. 2002-161451 JP 2004-107818 A International Publication WO00 / 73556

  However, there are no applications relating to filaments obtained by drawing a polyvinylidene fluoride filament while irradiating it with laser light. By the way, the polyvinylidene fluoride filament obtained by drawing by a conventional method has a problem that the transparency of the filament in water is not yet sufficient.

  Accordingly, an object of the present invention is to provide a polyvinylidene fluoride filament that is sufficiently transparent in water. Another object of the present invention is to provide a method for reliably improving the transparency of polyvinylidene fluoride filaments in water.

  As a result of intensive studies by the inventors, a polyvinylidene fluoride filament having a refractive index in the direction parallel to the filament axis of 1.452 or less and a tensile strength of 800 MPa or more exhibits the high tensile strength of the polyvinylidene fluoride filament. However, it was found that the transparency in water can be improved by suppressing the increase in the refractive index in the direction parallel to the filament axis.

  That is, in order to achieve the above-described object, according to one aspect of the present invention, the present invention provides a polyvinylidene fluoride having a refractive index in the direction parallel to the filament axis of 1.452 or less and a tensile strength of 800 MPa or more. System filament. According to this polyvinylidene fluoride filament, it is possible to improve transparency in water by suppressing the increase in the refractive index in the direction parallel to the filament axis while making the polyvinylidene fluoride filament high tensile strength.

  In addition, as a result of intensive investigations by the inventors, when a polyvinylidene fluoride filament is obtained by drawing the filament as a raw material while irradiating a laser beam, the filament is parallel to the filament axis of the polyvinylidene fluoride filament. It was found that the transparency of the polyvinylidene fluoride filament in water can be improved by setting the refractive index in this direction to 1.452 or less.

  That is, in order to achieve the above-described object, according to another aspect of the present invention, the present invention is a method for improving the transparency of polyvinylidene fluoride filaments in water, wherein a laser beam is applied to a filament as a material. The refractive index in the direction parallel to the filament axis of the polyvinylidene fluoride filament is adjusted to 1.452 or less by irradiating and stretching the filament while heating and softening. According to this method, the transparency of the polyvinylidene fluoride filament in water can be improved by setting the refractive index in the direction parallel to the filament axis of the polyvinylidene fluoride filament to 1.452 or less.

  Further, in the above-described method for improving the transparency of polyvinylidene fluoride filaments in water, the polyvinylidene fluoride filaments are irradiated with laser beams from a plurality of directions within a plane perpendicular to the filament axis direction with respect to the filaments that are the materials. Thus, the filament is preferably obtained by stretching while being softened by heating. According to this, since the filament used as a raw material can be heated comparatively uniformly, the said filament can be extended | stretched uniformly and the raise of the refractive index of a polyvinylidene fluoride type filament can be suppressed. Here, it is preferable that the laser light is irradiated straight onto the polyvinylidene fluoride filament.

  In the above-described method for improving the transparency of the polyvinylidene fluoride filament in water, the diameter of the filament used as the material is preferably 0.05 mm to 3.0 mm. According to this, by setting the diameter of the filament as the material to 0.05 mm to 3.0 mm, the filament as the material can be heated particularly uniformly, and the direction parallel to the filament axis of the polyvinylidene fluoride filament An increase in the refractive index can be suppressed.

  In the above-described method for improving the transparency of the polyvinylidene fluoride filament in water, the tensile strength in the axial direction of the polyvinylidene fluoride filament is preferably 800 MPa or more. According to this, by setting the refractive index in the direction parallel to the filament axis of the polyvinylidene fluoride filament to be 1.452 or less and the tensile strength in the axial direction to be 800 MPa or more, transparency in water is high, and high A strong polyvinylidene fluoride filament can be obtained.

  According to the present invention, the transparency of polyvinylidene fluoride filaments in water can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  In this embodiment, in order to improve the transparency of polyvinylidene fluoride (PVDF) filaments in water, PVDF filaments are drawn by irradiating the filaments as raw materials while irradiating the filaments with laser light. The refractive index in the filament axis direction is 1.45 or less. By using a PVDF filament having a refractive index of 1.452 or less in this way, the refractive index in the direction parallel to the filament axis of the PVDF filament becomes a value close to the refractive index of water 1.34. The transparency of the filament in water can be improved. Thereby, for example, when polyvinylidene fluoride filaments are used for fishing lines, fishing nets, etc., it becomes difficult for fish to notice the presence of PVDF filaments, and further catch can be expected.

  Here, the PVDF filament is a filament containing a polyvinylidene fluoride resin (PVDF resin) as a main component.

  Examples of the PVDF resin include a vinylidene fluoride homopolymer or a vinylidene fluoride copolymer having vinylidene fluoride as a monomer component. When higher strength is required, a vinylidene fluoride homopolymer is preferred. As a comonomer component in the copolymer, the alkene-derived monomer having 2 to 10 carbon atoms and at least one hydrogen atom substituted with a fluorine atom (for example, tetrafluoroethylene, hexafluoropropylene, At least one selected from the group consisting of ethylene trifluoride, ethylene trifluoride chloride and vinyl fluoride). The comonomer component is preferably hexafluoropropylene (hexafluoropropylene).

  Additive components include plasticizers (polyester plasticizers, phthalate ester plasticizers, etc.), nucleating agents (flavantrons, etc.), and other resin components with good compatibility with PVDF resins. As the plasticizer, the repeating unit composition is an ester of a dialcohol having 2 to 4 carbon atoms and a dicarboxylic acid having 4 to 6 carbon atoms, and the terminal group is a monovalent acid or monovalent alcohol having 1 to 3 carbon atoms. Polyester consisting of residues and having a molecular weight of 1500 to 4000 is preferably used. The addition amount of the plasticizer, the nucleating agent, and other resin components with respect to 100 parts by mass of the PVDF resin is preferably 0.1 to 10 parts by mass, 0.001 to 0.5 parts by mass, and 1 to 50 parts by mass, respectively.

  The PVDF filament may be a monofilament or a filament bundle in which a plurality of monofilaments are bundled. However, a monofilament is preferable in order to uniformly heat the PVDF filament as described later.

  The monofilament structure may be a single layer or may be composed of two or more layers. As such a structure, what consists of a core material (core part) extended in a longitudinal direction and the sheath material (sheath part) which consists of at least one layer arrange | positioned around this core material, for example is preferable.

  In addition, the refractive index of the PVDF-type filament may be 1.452 or less, preferably 1.450 or less, and more preferably 1.448 or less. Further, the tensile strength of the PVDF filament may be 800 MPa or more, preferably 900 MPa or more, and more preferably 1 GPa or more.

  Next, the manufacturing method of the PVDF type filament mentioned above is demonstrated. FIG. 1 shows a PVDF filament manufacturing apparatus 10. As shown in FIG. 1, an unstretched PVDF filament 1 that is a raw material is supplied from a first roll 12 at a constant supply speed v 1, and a coherent laser beam is irradiated to the PVDF filament 1 by a laser irradiation device 20. Thus, the PVDF filament 1 is heated and softened, and the PVDF filament 1 is stretched by winding the PVDF filament around the second roll 14 at a speed v2 higher than the supply speed v1.

  FIG. 2 shows an outline of the internal structure of the laser irradiation apparatus 20 provided in the PVDF filament manufacturing apparatus 10. FIG. 2 is a view of the inside of the laser irradiation apparatus 20 as viewed in the direction of the arrow A in FIG. 1, in other words, in the extending direction of the PVDF filament 1.

  The laser irradiation apparatus 20 includes a laser oscillation light source 21 that outputs a coherent laser beam, first to fourth total reflection mirrors 22, 23, 24, and 25 that reflect the laser, and a laser terminal portion 26 that absorbs the laser. It is equipped with. Here, each of the laser oscillation light source 21, the total reflection mirrors 22, 23, 24, 25 and the laser terminal portion 26 is arranged at an angle of 60 ° with the PVDF filament 1 as the center. Thus, by arranging each member at equiangular intervals, the PVDF filament 1 is irradiated with laser at an angle of 120 ° C. at an angle.

  That is, when a laser is output from the laser oscillation light source 21, the laser goes straight in the direction of the PVDF filament 1, and the first laser irradiation is performed on the PVDF filament 1. Here, part of the energy of the laser is absorbed by the PVDF filament 1, whereby the portion of the PVDF filament 1 on the laser oscillation light source 21 side is heated.

  On the other hand, the laser that has passed through the PVDF filament 1 and the laser that has passed through the side of the PVDF filament 1 are reflected by the first total reflection mirror 22 and the second total reflection mirror 23, and are reflected on the PVDF filament 1. On the other hand, the second laser irradiation is performed. The second laser irradiation angle is an angle rotated clockwise by 120 ° with respect to the first laser irradiation angle. The intensity of the laser irradiated for the second time is substantially equal to the intensity of the laser irradiated for the first time. Here, part of the energy of the laser is again absorbed by the PVDF filament 1, so that the portion of the PVDF filament 1 on the second total reflection mirror 23 side is heated.

  On the other hand, the laser that has passed through the PVDF filament 1 and the laser that has passed through the side of the PVDF filament 1 are reflected by the third total reflection mirror 24 and the fourth total reflection mirror 25, and are reflected on the PVDF filament 1. On the other hand, the third laser irradiation is performed. The third laser irradiation angle is an angle rotated 120 ° clockwise relative to the second laser irradiation angle. The intensity of the laser irradiated for the third time is substantially equal to the intensity of the laser irradiated for the first time and the second time. Here, part of the energy of the laser is again absorbed by the PVDF filament 1, so that the portion of the PVDF filament 1 on the fourth total reflection mirror 25 side is heated. The laser that has passed through the PVDF filament 1 and the laser that has passed through the side of the PVDF filament 1 are finally absorbed by the laser terminal portion 26.

  According to the manufacturing method of the present embodiment, as described above, the unstretched PVDF filament 1 as a material is irradiated with laser light from a plurality of directions in a plane perpendicular to the filament axis direction. According to this, since the PVDF filament 1 as a material can be heated relatively uniformly in the cross section of the PVDF filament 1, by stretching the PVDF filament 1 while uniformly heating and softening, While increasing the tensile strength of the PVDF filament 1, the increase in the refractive index in the direction parallel to the filament axis of the PVDF filament 1 can be suppressed.

  That is, while the refractive index of water is 1.34, the refractive index of crystallized polyvinylidene fluoride is 1.48, and the refractive index of amorphous polyvinylidene fluoride is 1.37. Therefore, in order to improve the transparency of the PVDF filament 1 in water, it is necessary to reduce the proportion of crystals contained in the PVDF filament 1 and increase the proportion of non-crystals. On the other hand, in order to reinforce the PVDF filament 1, when the PVDF filament as a raw material is heated and stretched, PVDF is oriented and crystallized in the filament axial direction, and therefore the filament of the PVDF filament 1 The refractive index increases in the direction parallel to the axis. On the other hand, in the manufacturing method of the present embodiment, the PVDF filament 1 is stretched while being uniformly heated and softened, so that an increase in the refractive index in the direction parallel to the filament axis of the PVDF filament 1 can be suppressed. .

  In the manufacturing method of the present embodiment described above, a single laser output from the laser oscillation light source 21 is reflected using the plurality of total reflection mirrors 22, 23, 24, 25, so that the PVDF filament 1 is reflected. The laser is irradiated 3 times. Thereby, the PVDF filament 1 can be heated particularly uniformly. Also, since a plurality of total reflection mirrors 22, 23, 24, 25 are used, only one laser oscillation light source 21 is required, which is preferable from the viewpoint of simplifying the laser irradiation apparatus 20.

  The amount of laser energy absorbed by the PVDF filament 1 depends on the wavelength of the laser, the diameter of the filament, the feed rate by the roll, the density, the heat capacity, the absorption rate, and the like. Therefore, in this embodiment, the number of times of laser irradiation is 3 and the irradiation angle is 120 °, but in other embodiments, the wavelength of the laser, the diameter of the filament, the feed rate by the roll, the density, the heat capacity, the absorption rate. Depending on the above, the PVDF filament 1 may be irradiated by determining the number of times of laser irradiation to be three or more. In addition, as a laser irradiation method, a laser immediately after irradiating the filament is branched using a half mirror and then further irradiated to the filament, or a spherical mirror is arranged around the filament to irradiate the laser. There is also a method of irradiating the filament after being reflected by the mirror.

  In particular, as in the manufacturing method of the present embodiment described above, in order to uniformly heat the PVDF filament 1, it is preferable to irradiate the PVDF filament 1 with a laser in a straight line state. Here, the straight-running laser is a laser that travels linearly from the laser oscillation light source 21 without a lens or the like arranged on the traveling path. In addition, the laser in the straight traveling state includes a laser whose width slightly increases as it progresses. By irradiating the laser in a straight line in this way, the PVDF filament 1 can be heated particularly uniformly, and the tensile strength of the PVDF filament 1 can be increased while the direction parallel to the filament axis of the PVDF filament 1 is increased. An increase in refractive index can be suppressed.

  In the method of the present embodiment described above, by using an unstretched PVDF filament as a raw material having a diameter of 0.05 mm to 3.0 mm, the structure unevenness due to the uneven temperature distribution is reduced, The refractive index in the direction parallel to the filament axis of the PVDF filament can be set to 1.452 or less. Further, in order to make the refractive index in the direction parallel to the filament axis of the PVDF filament to be 1.452 or less, it is preferable that the diameter of the unstretched PVDF filament as a material is smaller. That is, the diameter of the unstretched PVDF filament used as a material is preferably 0.05 mm to 3.0 mm, more preferably 0.05 mm to 1.0 mm, and still more preferably 0.05 mm to 0.5 mm. It is. In addition, as described above, it is preferable to reduce the diameter of the PVDF filament and uniformly heat and stretch the PVDF filament from the viewpoint of increasing the tensile strength in the filament axial direction.

  In the above laser irradiation, the feed rate of the PVDF filament is preferably 0.1 m to 1000 m / min, more preferably 0.5 m to 500 m / min, and further preferably 1.0 m to 200 m / min. It is. Further, the PVDF filament may be heated by irradiating a laser over a section of 0.1 mm to 100 mm in the axial direction of the PVDF filament, and the filament temperature may be increased and softened by 100 K to 400 K within this section. The instantaneously heated PVDF-based filament is instantaneously stretched by an external force, whereby molecular chains are uniformly and highly oriented, and a high-strength PVDF-based filament can be obtained.

The laser oscillation light source 21 may be a coherent light source using laser oscillation. As the laser, a gas, a solid, a semiconductor, a dye, an excimer, or a free electron source can be used. Laser may be utilized as the wavelength is in the infrared range, and having an oscillation wavelength 9μm~12μm to carbon dioxide gas and emission source, trace the ^{Nd 3+} added yttrium aluminum garnet _{(3Y 2 O 3 · 5Al 2} O ₃ ) An oscillation wavelength having an emission wavelength of 0.9 μm to 1.2 μm is excellent. Of these, the carbon dioxide laser is particularly effective for implementation because the PVDF filament is in a wavelength band that exhibits moderate absorption.

  In addition, the manufacturing method of the PVDF-type filament mentioned above is an example, and if the refractive index of the direction parallel to the filament axis of the PVDF-type filament obtained as a result is 1.452 or less, PVDF-type filament will be manufactured by another manufacturing method. May be manufactured. For example, in the PVDF filament manufacturing method described above, the PVDF filament is stably stretched in one step up to a high magnification, but may be stretched in multiple steps instead. In the case of multiple stages, at least one stage may be laser stretched.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to the following Example. In addition, the refractive index, the strong elongation, the heat shrinkage rate, and the crystal structure of the fiber obtained in this example were measured or evaluated by the following methods.

(1) Refractive index
The refractive index in the direction perpendicular to and parallel to the fiber axis was measured using an interfaco interference microscope manufactured by Carl-Zeiss. The birefringence was obtained by subtracting the refractive index in the vertical direction from the refractive index in the direction parallel to the fiber axis. The average refractive index was obtained by adding twice the refractive index in the vertical direction to the refractive index in the direction parallel to the fiber axis and dividing by 3. The measurement temperature was room temperature (25 ° C.), and an aqueous glucose solution was used as the immersion liquid.
(2) Strong elongation
The tensile strength was measured according to JIS L1013.
(3) Thermal contraction rate It was immersed in 80 degreeC water for 10 minutes, and the thermal contraction rate was computed from the yarn length ratio before and behind that. The initial test length was 500 mm.
(4) Crystal structure The presence or absence of α-type crystals was evaluated from a wide-angle X-ray diffraction image.

Table 1 shows the processing conditions and test results of each example and comparative example. In Table 1, “parallel” of the refractive index means the refractive index in the direction parallel to the filament axis direction, and “vertical” of the refractive index means the refractive index in the direction perpendicular to the filament axis direction. Means.

Example 1
A monofilament undrawn yarn having a diameter of 0.2 mm was produced by spinning poly (vinylidene fluoride) having an inherent viscosity of 1.3 dl / g at a spinning temperature of 270 ° C. The obtained monofilament undrawn yarn was once wound, and then stretched at a draw ratio of 6.0 times and a yarn feed speed of 3 m / min using a laser oscillation light source using carbon dioxide gas as a release source as a heat source. The wavelength of the light source was 10.6 μm, the laser output was 4.9 W, the irradiation diameter was 5.0 mm, and irradiation of the monofilament undrawn yarn was performed in three directions (FIG. 1). Table 1 shows the results of measuring the refractive index, strong elongation, and heat shrinkage of the drawn yarn and evaluating the crystal structure.

Example 2
A drawn yarn was produced in the same manner as in Example 1 except that the draw ratio was 5.5 times. Table 1 shows the results of measuring the refractive index, strong elongation, and heat shrinkage of the drawn yarn and evaluating the crystal structure.

Example 3
A drawn yarn was produced in the same manner as in Example 1 except that the diameter of the monofilament undrawn yarn was 0.3 mm and the laser output was 5.1 W. Table 1 shows the results of measuring the refractive index, strong elongation, and heat shrinkage of the drawn yarn and evaluating the crystal structure.

Example 4
A drawn yarn was produced in the same manner as in Example 3 except that the draw ratio was 5.5 times. Table 1 shows the results of measuring the refractive index, strong elongation, and heat shrinkage of the drawn yarn and evaluating the crystal structure.

Comparative Example 1
A drawn yarn was prepared in the same manner as in Example 1 except that the heat source for drawing was changed to 165 ° C. glycerin. Table 1 shows the results of measuring the refractive index, strong elongation, and heat shrinkage of the drawn yarn and evaluating the crystal structure.

Comparative Example 2
A drawn yarn was prepared in the same manner as in Example 2 except that the heat source for drawing was changed to 165 ° C. glycerin. Table 1 shows the results of measuring the refractive index, strong elongation, and heat shrinkage of the drawn yarn and evaluating the crystal structure.

Comparative Example 3
A drawn yarn was produced in the same manner as in Example 2 except that the heat source for drawing was 165 ° C. hot air. Table 1 shows the results of measuring the refractive index, strong elongation, and heat shrinkage of the drawn yarn and evaluating the crystal structure.

  In Example 1-4, the tensile strength in the filament axial direction of 800 MPa or more is ensured by stretching the unstretched PVDF filament as a raw material while uniformly heating with a laser. In particular, in Example 1, the tensile strength exceeding 1 GPa is realized in spite of the single-stage stretching. Moreover, in Example 1-4, the filament used as a raw material is stretched while being uniformly heated with a laser, thereby suppressing an increase in the refractive index in the direction parallel to the filament axis, and the refractive index in the direction parallel to the filament axis. Are both 1.45 or less. Thereby, since the refractive index of a PVDF type filament can be approximated to the refractive index of water, the transparency of the PVDF type filament in water is improved.

  On the other hand, in Comparative Example 1-3, unstretched PVDF filaments that are raw materials are stretched while being heated by heat transfer from glycerin or hot air. In Comparative Example 1, although the tensile strength is as high as 933 MPa, the refractive index in the direction parallel to the filament axis is as high as 1.453. In Comparative Example 2, although the refractive index in the direction parallel to the filament axis is a low value of 1.447, the tensile strength is a low value of 702 MPa. Further, in Comparative Example 3, although the refractive index in the direction parallel to the filament axis is as low as 1.451, the tensile strength is as low as 790 MPa. Comparing Example 1-4 and Comparative Example 1-3, Example 1-4 has the characteristics that the tensile strength is 800 MPa or more and the refractive index is 1.452 or less, and Comparative Example 1-3. It turns out that it is excellent with respect to.

  Moreover, the test result about the PVDF-type filament acquired together with said Example 1-4 is shown in the following table | surface. In particular, the test results regarding the mechanical properties of PVDF filaments are shown in Tables 1-1 and 1-2 below. Moreover, the test result regarding the refractive index of a PVDF-type filament is shown to the following tables 2-1 and 2-2. Moreover, the test result regarding the thermal contraction rate of a PVDF-type filament is shown to the following tables 3-1 and 3-2. Tables 1-1, 2-1, and 3-1 show the results of stretching a PVDF filament having a diameter of 0.2 mm at a draw ratio of 5.0 times, 5.5 times, and 6.0 times. . Tables 1-2, 2-2, and 3-2 show the results of stretching a 0.3 mm diameter PVDF filament at stretch ratios of 5.5 times, 6.0 times, and 6.5 times. ing.

It is the schematic which shows the manufacturing apparatus of a PVDF type filament. It is the schematic which shows the internal structure of a laser irradiation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... PVDF type filament, 10 ... Manufacturing apparatus, 12 ... 1st roll, 14 ... 2nd roll, 20 ... Laser irradiation apparatus, 21 ... Laser oscillation light source, 22-25 ... Total reflection mirror, 26 ... Laser termination | terminus part .

Claims (7)

  A polyvinylidene fluoride filament having a refractive index in the direction parallel to the filament axis of 1.452 or less and a tensile strength of 800 MPa or more. A method for improving the transparency of polyvinylidene fluoride filaments in water,
A method characterized in that the refractive index of a polyvinylidene fluoride filament is adjusted to 1.45 or less by irradiating a filament as a material with laser light and stretching the filament while heating and softening.   The polyvinylidene fluoride filament is obtained by irradiating a laser beam from a plurality of directions in a plane perpendicular to the filament axis direction and stretching the filament while heating and softening the filament as a raw material. The method of claim 2, wherein the method is characterized in that:   4. The method according to claim 3, wherein the laser light is irradiated to the polyvinylidene fluoride filament in a straight traveling state.   The diameter of the said filament used as a raw material is 0.05 mm-3.0 mm, The method of any one of Claims 2-4 characterized by the above-mentioned.   The method according to any one of claims 2 to 5, wherein the tensile strength in the axial direction of the polyvinylidene fluoride filament is 800 MPa or more. A polyvinylidene fluoride filament produced by the method according to any one of claims 2 to 6.

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