JPH06116812A - Production of polyester monofilament - Google Patents

Abstract

PURPOSE:To provide a polyester monofilament good in abrasion resistance without causing a trouble due to the staining of an extrusion nozzle by preliminarily melt-kneading a polyester and a polyolefinic thermoplastic elastomer and subsequently extrusion-spinning the kneaded product from a spinneret having a specific extrusion nozzle. CONSTITUTION:A polyester such as polyethylene terephthalate and a polyolefinic thermoplastic elastomer containing polypropylene, etc., as a hard segment and ethylene-propylene-diene terpolymer as a soft segment are preliminarily melt- blended in a V blender under a nitrogen atmosphere, and subsequently formed into blend chips. The blend chips are melt-extruded from a spinneret having a condition satisfying an inequality: 1.5<=L/D<=5.0 wherein D is the diameter (mm) of the extrusion nozzle and L is the length (mm) of the extrusion nozzle, once cooled, drawn at 120 deg.C and subsequently subjected to a relaxed heat set treatment to produce the uniform monofilament good in abrasion resistance, and useful for paper production nets, filters, belt cloths, while preventing a trouble caused by the adhesion of stains to the periphery of the extrusion nozzle.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a papermaking net, a filter,
The present invention relates to a method for producing a polyester monofilament useful as an industrial material such as a belt cloth.

[0002]

2. Description of the Related Art Generally, thermoplastic polyesters such as polyethylene terephthalate have excellent mechanical properties and chemical properties, and have been widely used as molded articles such as fibers and films. However, when the polyester monofilament is used for contact with other substances such as particles, structures, etc. of metal, ceramic, plastic, etc. for industrial use, the particles or structures are vulnerable to abrasion damage, and therefore polyester Nets and fabrics using monofilaments have a shortcoming that they have a short life as products. For example, in the paper industry,
Conventionally, acid paper has been mainly manufactured, but as the problem of deterioration of paper over time becomes more prominent, conversion to neutral paper has become popular. Along with the conversion from acidic paper to neutral paper, the filler for paper called filler was changed from talc to calcium carbonate. Since calcium carbonate particles are harder than talc particles, the paper making net (hereinafter referred to as wire) used in the papermaking process wears quickly. Especially, the polyester monofilament wire is a polyamide monofilament wire such as nylon 6. It has a short life compared to the above. Nylon wire has the advantage that it is relatively hard to wear as mentioned above, but it has the fatal drawback that the dimensions of the wire change due to moisture during papermaking, which causes troubles in papermaking. In this case, improvement in abrasion resistance of a polyester monofilament wire having good dimensional stability has been desired.

Various proposals have hitherto been made to improve the abrasion resistance of polyester monofilaments.
For example, although alumina powder, silicon carbide, a polyester monofilament containing abrasive particles such as a zirconia-based abrasive has a slight improvement in the wear resistance effect,
The yarn quality is poor due to the poor dispersion of the abrasive particles in the polyester, and various rollers and guides that come into contact with the monofilament and various fabrics using the monofilament in the monofilament manufacturing process and the weaving process of various fabrics using the monofilament. It has a defect such as scratching damage to the surface of the kind and the like. Also, JP-A-63-429
No. 76 discloses a method of applying a hard coating such as a polysiloxane coating and a crosslinked acrylic coating on the surface of a monofilament, but the surface coating is liable to fall off, which causes a problem in terms of durability. Had. On the other hand, Japanese Patent Laid-Open No. 2-80688 proposes a fabric for papermaking having improved abrasion resistance, which uses a monofilament containing polyethylene terephthalate containing a specific amount of thermoplastic polyurethane. The resin is not practical because it decomposes at the melt spinning temperature of polyethylene terephthalate, making spinning difficult and having a large industrial problem. In view of such a situation, various investigations have been conducted, and the present inventors have found that a monofilament obtained by dispersing a thermoplastic polyolefin-based elastomer in polyester exhibits good abrasion resistance. However, in the melt spinning in the monofilament manufacturing process, stains occur around the discharge holes of the spinneret, the spinning is not stable, and it is difficult to obtain a uniform yarn.

By the way, Japanese Patent Laid-Open No. 4-2815 describes a first component consisting of a resin containing 50% by weight or more of a thermoplastic elastomer, and a resin containing a thermoplastic resin other than the thermoplastic elastomer as a substantial main component. A composite stretched monofilament consisting of a combination with a certain second component and a method for producing the same have been proposed, but a composite stretched monofilament having a large coefficient of friction obtained by a method in which the first component and the second component are extruded from different orifices and stretch-formed. The present invention relates to a monofilament, and is clearly different from the present invention in the object, constitution, and means of the invention.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a spinning spinneret at the time of melt spinning for producing polyester monofilaments which are free from the above-mentioned various drawbacks and which are useful as industrial materials such as papermaking nets, filters and belt cloths. It is an object of the present invention to provide a method for stably producing the monofilament by preventing the generation of dirt around the discharge holes.

[0006]

The above-mentioned object of the present invention is to melt and knead polyester and a thermoplastic polyolefin-based elastomer in advance and then to discharge the spinneret (hereinafter,
This is achieved by a method for producing a polyester monofilament, characterized in that spinning is performed under the condition that the diameter D (mm) of the discharge hole) and the length L (mm) of the discharge hole satisfy the relationship of the following formula. 1.5 ≦ L / D ≦ 5.0

The present invention will be described in detail below. In the present invention, the polyester forming the monofilament is mainly composed of a difunctional component such as an aromatic dicarboxylic acid or a dialkyl ester thereof and a glycol component, and is preferably composed mainly of polyethylene terephthalate. . The polyester mainly composed of polyethylene terephthalate may be a homopolyester or a copolyester, and examples of the copolymerization component include adipic acid, sebacic acid, phthalic acid, naphthalene-2,6-dicarboxylic acid and 5-sodium. Dicarboxylic acid components such as sulfoisophthalic acid, polycarboxylic acid components such as trimellitic acid and pyromellitic acid, oxycarboxylic acid components such as p-oxyethoxybenzoic acid, and tetramethylene glycol, hexamethylene glycol, diethylene glycol, propylene glycol ,
A diol component such as neopentyl glycol, polyoxyalkylene glycol, p-xylylene glycol, 1,4-cyclohexanedimethanol, 5-sodium sulforesorcin may be contained.

The thermoplastic polyolefin-based elastomer (hereinafter referred to as a thermoplastic elastomer) contained in the polyester monofilament obtained by the production method of the present invention exhibits rubber elasticity at ordinary temperature and exhibits plasticity similar to that of thermoplastic at high temperature. It is a polymer and is composed of a blended product in which a polyolefin such as polypropylene or polyethylene is mainly used as a hard segment and an ethylene / propylene / diene terpolymer is mainly used as a soft segment. There are various types of thermoplastic elastomers, from soft ones to fairly hard ones, but when the thermoplastic elastomers are relatively soft, the effect of improving wear resistance, which is the object of the present invention, tends to be remarkable. It is preferable that it is specified in JIS K630.
JIS-A hardness (hereinafter referred to as JIS-A
A hardness of 85 or less can be preferably used. Further, the thermoplastic elastomer may contain various oils for improving kneadability and moldability,
Further, a soft segment mainly composed of an ethylene / propylene / diene terpolymer may be partially crosslinked. The content of the thermoplastic elastomer in the polyester monofilament is preferably 1% by weight or more in order to impart sufficient abrasion resistance, while maintaining the strength and elongation property and free from the monofilament wire diameter unevenness and spinning. It is preferably 40% by weight or less in order to prevent the discharge holes from being contaminated. More preferably, it is 5% by weight or more and 30% by weight or less.

The polyester monofilament obtained by the production method of the present invention is a continuous yarn made of polyester containing a thermoplastic elastomer, and the cross-sectional shape thereof is not limited to a circular shape, but also has an irregular cross-sectional shape such as a triangle, a square or a regular polygon. Although it may have, from the viewpoint of improving wear resistance,
A circular cross-sectional shape is preferred because it is less likely to wear. The diameter of the cross-sectional shape (diameter equivalent to circular cross-section other than circular) can be appropriately determined depending on the application, but 0.01-3 mmφ is often used. In addition, 0.07 to 2.0 mmφ is often used for industrial materials such as papermaking nets, filters and belt cloths, and therefore the spinneret discharge hole diameter D is 0.5 to 8.0 m.
mφ is good. Although the strength of the monofilament varies depending on its use, it is preferably 3.0 g / denier or more for a paper making net.

A specific example of the method for producing a polyester monofilament containing the thermoplastic elastomer of the present invention will be described below. First, in the present invention, polyester and a thermoplastic elastomer are kneaded prior to melt spinning. The kneading can be performed at any stage from the completion of the polycondensation of the polyester to the spinning of the monofilament. For example, immediately after the completion of the polycondensation of the polyester, a thermoplastic elastomer is added to the molten polyester in a polymerization can.・ Kneading method, or adding thermoplastic elastomer chips to dried polyester chips ・ After chip blending, melt spinning while kneading with an extruder type spinning machine, or a predetermined amount of polyester chips and thermoplastic elastomer with a chip quantitative feeder And a method of kneading the polyester and the thermoplastic elastomer in advance with a uniaxial or biaxial extruder kneader and then molding into chips.

Prior to melt spinning, the polyester and the thermoplastic elastomer are forcedly kneaded at least once. By carrying out this forced kneading before melt spinning, it is possible to prevent the occurrence of picking and bending during spinning, and the occurrence of stains around the discharge holes, and also to prevent yarn breakage during spinning and drawing, and to reduce the unevenness of the wire diameter. A monofilament having good physical properties can be obtained. As the kneading means before the melt spinning, a static mixer such as a static mixer or a high mixer may be used together. The polyester containing the thermoplastic elastomer thus melt-kneaded in advance is then melt-spun. The discharge hole in the spinneret referred to in the present invention refers to a hole portion on the discharge surface side of the spinneret. The melt spinning may be performed by any method such as a spinning machine with a kneading device such as an extruder or a melt pressure type, but the diameter D (mm) of the discharge hole (equivalent to a circular shape other than circular) and the length L of the discharge hole ( (mm) must be spun on condition that satisfies the relationship of the following formula. 1.5 ≦ L / D ≦ 5.0 More preferably, L / D in the above formula is 2.0 or more and 4.0 or less. If L / D is less than 1.5, dirt adheres to the periphery of the discharge hole, and the spun yarn is bent or spiked.
In addition, as the spinning time elapses, stains increase and the spun yarn is cut off. On the other hand, L / D is 5.0
If it is larger than the above range, stains adhere to the periphery of the discharge hole due to an increase in the dispersion effect of the molten polymer discharged from the discharge hole, which is not preferable.

As the temperature during melt spinning, the usual melt spinning temperature of polyester can be adopted. That is, it can be adopted in the range of not less than the melting temperature of the polyester and not more than the thermal decomposition temperature,
290 to avoid thermal decomposition of the thermoplastic elastomer
C. or less is preferable. For the same reason, the average contact time with the molten polyester is preferably 15 minutes or less in total, more preferably 10 minutes or less.

In the polymer to be melt-spun according to the present invention, various antioxidants, various inert particles such as titanium oxide, various polymers other than thermoplastic elastomers, various metal compounds as catalysts usually used in the production of polyester, and phosphorus. Coloring inhibitors such as compounds, various dyes and pigments, etc. may be contained.

According to the production method of the present invention, a polyester monofilament containing a thermoplastic elastomer, which is useful as an industrial material for papermaking nets, filters, belt cloths, etc., without causing stains around discharge holes during melt spinning Can be manufactured stably.

[0015]

The present invention will be described in more detail with reference to the following examples. In the examples, the condition of the stain around the discharge hole was determined by observing the periphery of the discharge hole 3 hours after the start of melt spinning and determining the presence or absence of the stain, unless otherwise specified. Further, the evaluation of the monofilament wire diameter unevenness was performed by the following method.

<Evaluation method of wire diameter unevenness> Using a laser wire diameter measuring device, a monofilament 250 m was measured at a speed of 50 m / min for 5 minutes to measure the wire diameter, and the average value of the measured values was taken as the filament diameter. The difference between the maximum value and the minimum value was defined as the wire diameter spot. In the case where the monofilament is used as a papermaking net, the line diameter unevenness has a difference of 20 μm between the maximum value and the minimum value measured by this evaluation method in view of the relationship with the surface uniformity of paper products.
It is required to be m or less.

Example 1 Intrinsic viscosity 0.70 (25 in a mixed solvent of phenol and tetrachloroethane 1: 1) dried at 160 ° C. for 8 hours under vacuum
Polyethylene terephthalate (measured at ° C) (hereinafter PE
90 parts by weight of a chip, a polyolefin thermoplastic elastomer (Mitsui Petrochemical Industry Co., Ltd. "Millastomer" (registered trademark) 5030N, JIS A hardness 5)
0) 10 parts by weight were mixed in a V-type blender under a nitrogen atmosphere to obtain a blend chip. Next, this blended chip was subjected to melt-kneading followed by melt-spinning in a uniaxial extruder type melt spinning machine equipped with a discharge hole having a discharge hole diameter D of 1.0 mm and a discharge hole length L of 3.5 mm. Then, it is cooled once, and further stretched 5.7 times at 120 ° C., then 0.9
Thread relaxation diameter 0.22m
m, a wire diameter irregularity of 4 μm, and a strength of 4.1 g / denier were obtained. As shown in Table 1, adhesion of stains around the discharge holes after spinning was not recognized.

Example 2 Melt spinning was carried out in the same manner as in Example 1 except that the spinneret had a discharge hole having a diameter D of 1.0 mm and a discharge hole length L of 1.6 mm. Thread cross section diameter 0.2
A polyester monofilament having a diameter of 2 mm, a wire diameter unevenness of 4 μm, and a strength of 4.2 g / denier was obtained. As shown in Table 1, adhesion of dirt to the periphery of the discharge hole after spinning was only slightly recognized.

Example 3 Melt spinning was carried out in the same manner as in Example 1 except that the spinneret was changed to one having a discharge hole diameter D of 1.0 mm and a discharge hole length L of 4.8 mm. Thread cross section diameter 0.2
A polyester monofilament having a diameter of 2 mm, a wire diameter unevenness of 7 μm, and a strength of 4.2 g / denier was obtained. As shown in Table 1, adhesion of dirt to the periphery of the discharge hole after spinning was only slightly recognized.

Example 4 Melt spinning was carried out in the same manner as in Example 1 except that the spinneret had a discharge hole having a diameter D of 1.0 mm and a discharge hole length L of 2.5 mm. Thread cross section diameter 0.2
A polyester monofilament having a diameter of 2 mm, a wire diameter unevenness of 4 μm, and a strength of 4.1 g / denier was obtained. As shown in Table 1, adhesion of stains around the discharge holes after spinning was not recognized.

Comparative Example 1 Melt spinning was attempted in the same manner as in Example 1 except that the spinning machine was changed from the uniaxial extruder type to the melt pressure type without forced kneading function. Therefore, the discharged polymer was so disturbed that melt spinning was impossible.

Comparative Example 2 Melting was carried out in the same manner as in Example 1 except that the spinneret was changed to one having a discharge hole diameter D of 1.0 mm and a discharge hole length L of 1.3 mm. Spinning is performed and the yarn cross section diameter is 0.2.
A polyester monofilament having a diameter of 2 mm, a wire diameter unevenness of 7 μm, and a strength of 3.9 g / denier was obtained. As shown in Table 1, bending of the spun yarn occurred during spinning, and a black cylindrical stain having a length of about 1 mm adhered to the periphery of the discharge hole after spinning.

Comparative Example 3 Melting was carried out in the same manner as in Example 1 except that the spinneret had a discharge hole having a diameter D of 1.0 mm and a discharge hole length L of 1.0 mm. Spinning was performed. As shown in Table 1, after 30 minutes from the start of spinning, severe bending of the spun filament occurred, and after 2 hours, the spun filament was cut and it became impossible to continue spinning. . In addition, a black cylindrical stain having a length of about 2 mm was attached to the periphery of the discharge hole.

Comparative Example 4 Melting was carried out in the same manner as in Example 1 except that the spinneret was changed to one having a discharge hole diameter D of 1.0 mm and a discharge hole length L of 5.5 mm. Spinning was performed. As shown in Table 1, the discharged polymer had a large tendency to be dispersed during spinning, and a black cylindrical stain having a length of about 1.5 mm was attached to the periphery of the discharge hole.

[0025]

[Table 1]

[0026]

The following effects can be obtained by adopting the method for producing a polyester monofilament of the present invention. (1) It is possible to prevent various troubles due to adhesion of stains around the discharge holes which occur when melt-spinning a polyester monofilament in which a thermoplastic polyolefin elastomer is kneaded. (2) The obtained polyester monofilament has good abrasion resistance and is homogeneous, so a paper net, filter,
It is useful as an industrial material such as belt cloth.

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Claims (1)

[Claims] 1. A condition under which a diameter D (mm) of a discharge hole of a spinneret and a length L (mm) of the discharge hole satisfy the following expression after melt-kneading polyester and a thermoplastic polyolefin-based elastomer in advance. A method for producing a polyester monofilament, which comprises spinning with a polyester. 1.5 ≦ L / D ≦ 5.0