JP2002266164A - Polyester monofilament, method for producing the same, and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester monofilament equipped with each characteristic of a high Young's modulus and low heat shrinkage in a good balance, a method for producing the same and its use represented by an industrial material. SOLUTION: This polyester monofilament consists of a polyethylene naphthalate, and has >=8,000 N/mm<2> Young's modulus and <=10% dry heat shrinkage at 180 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester monofilament, a method for producing the same and a use thereof. More specifically, the present invention relates to a polyethylene naphthalate monofilament having the characteristics of high Young's modulus and low heat shrinkage in a balanced manner, an efficient production method thereof, and its use represented by industrial materials.

[0002]

2. Description of the Related Art Conventionally, polyester fibers have been used as various industrial materials because of their excellent physical and chemical properties. However, in the fields of communication cable members and industrial fabrics, polyester fibers have high strength and high Young's modulus. In recent years, there has been an increasing demand for polyester fibers having both low heat shrinkage (that is, a dry heat shrinkage at 180 ° C. of 10% or less).

A method for producing a typical polyethylene terephthalate monofilament among polyester fibers is described in JP-A-6-220718 and JP-A-Hei.
No. 0-168661, and these prior arts deal with the above demand for a higher Young's modulus by increasing the draw ratio. There is a limit in increasing the Young's modulus because deterioration of the properties is remarkably exhibited.

[0004] In order to reduce the heat shrinkage of polyester fibers, a method of improving the relaxation heat treatment efficiency by increasing the temperature of the relaxation heat treatment step or decreasing the relaxation heat treatment magnification has been adopted. However, in this case, the effect of increasing the Young's modulus by the high stretching ratio was lost, and the high Young's modulus could not be maintained at the same time.

In other words, there is a trade-off between high Young's modulus and low heat shrinkage of polyester fiber, and there is a limit in simultaneously satisfying high Young's modulus and low heat shrinkage in polyethylene terephthalate monofilament.

Also, Japanese Patent No. 2948006 and Japanese Patent Application Laid-Open No. H11-279833 propose polyethylene naphthalate fibers, all of which relate to multifilaments and monofilaments having a small wire diameter. Not only is it not mentioned in the field of monofilaments with general fineness and diameter,
There is no disclosure of a monofilament satisfying both a high Young's modulus and a low heat shrinkage at the same time.

[0007]

SUMMARY OF THE INVENTION The present invention has been achieved as a result of studying to solve the above-mentioned problems in the prior art.

Accordingly, an object of the present invention is to provide a polyethylene naphthalate monofilament having the characteristics of high Young's modulus and low heat shrinkage, which could not be expressed by polyethylene terephthalate at all, an efficient production method thereof, and industrial materials. The purpose is to provide the use represented by.

[0009]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above-mentioned object, and found that when producing polyethylene monofilament by melt-spinning, cooling, drawing and heat-treating polyethylene naphthalate, the above-mentioned cooling was carried out. As a condition, while adopting a cooling temperature much higher than before, the stretching ratio was set higher, and the heat treatment conditions were strictly defined, thereby equilibrating the characteristics of high Young's modulus and low heat shrinkage. Polyethylene naphthalate monofilament was obtained, and it was found that this monofilament exerted the best effect when applied as an industrial material, and the present invention was reached.

That is, the polyester monofilament of the present invention comprises ethylene-2,6-naphthalate units of 8
A monofilament composed of polyethylene naphthalate containing 5 mol% or more, having an intrinsic viscosity of 0.5 or more, and having a terminal carboxyl group concentration of 40 equivalents / t or less.
Young's modulus measured according to L1013 is 8000 N / m
m ² or more, measured according to JIS L1013 180
The dry heat shrinkage at 10 ° C. is 10% or less.

The polyester monofilament of the present invention has a fiber diameter of 0.05 to 4.00 mm.
And the tensile strength measured according to JIS L1013 is 3.0 cN / dtex or more and the tensile elongation is 5
% Are preferred conditions.

Further, the method for producing a polyester monofilament of the present invention having the above-mentioned properties is characterized in that
A 6-naphthalate unit containing at least 85 mol%, an intrinsic viscosity of at least 0.5, and a terminal carboxyl group concentration of 40 equivalents /
The undrawn yarn obtained by melt-extruding a polyethylene naphthalate having a temperature of t or less from a melt spinning machine is referred to as a polymer having a glass transition point of -3.
After cooling with a cooling solvent having a temperature of (0 ° C.) to (glass transition point of polymer + 30 ° C.), the film is stretched so that the total stretching ratio becomes 5.0 times or more, and then relaxed to 0.7 to 1.0 times. Or a heat treatment at a constant length magnification.

Further, the polyester monofilament of the present invention having the above-mentioned properties can be used as various industrial materials, but exhibits the best effect particularly when used as a cable member such as a communication cable reinforcing wire. .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The polyethylene naphthalate polymer used in the present invention is a polymer containing 85 mol% or more of polyethylene-2,6-naphthalate units, having an intrinsic viscosity of 0.5 or more, preferably 0.6 or more, and a terminal carboxyl group. The base concentration is 40 equivalents / t or less, preferably 30 equivalents / t
The following polymer.

The polyethylene naphthalate polymer can contain other dicarboxylic acid components and diol components as long as it is less than 15 mol%, and the other dicarboxylic acid components include terephthalic acid, isophthalic acid and phthalic acid. , Diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, benzophenone dicarboxylic acid, phenylindane dicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, cyclohexane dicarboxylic acid and decalin dicarboxylic acid, etc., as other diol components Is ethylene glycol, propylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, neopentylene Recall, cyclohexanediol, aliphatic glycols such as cyclohexane dimethanol, o- xylylene glycol, p- xylylene glycol, m- xylylene glycol, 1,4-bis (2
-Hydroxyethoxy) benzene, 1,4-bis (2-
(Hydroxyethoxyethoxy) benzene, 4,4′-bis (2-hydroxyethoxy) biphenyl, 4,4′-
Bis (2-hydroxyethoxyethoxy) biphenyl,
2,2-bis [4- (2-hydroxyethoxy) phenyl] propane, 2,2-bis [4- (2-hydroxyethoxyethoxy) phenyl] propane, 1,3-bis (2-hydroxyethoxy) benzene, 1,3-bis (2-hydroxyethoxyethoxy) benzene, 1,2
-Bis (2-hydroxyethoxy) benzene, 1,2-
Bis (2-hydroxyethoxyethoxy) benzene,
Aromatic glycols such as 4,4'-bis (2-hydroxyethoxy) diphenylsulfone and 4,4'-bis (2-hydroxyethoxyethoxy) diphenylsulfone;
And diphenols such as hydroquinone, 2,2-bis (4-hydroxyphenyl) propane, resorcin, catechol, dihydroxynaphthalene, dihydroxybiphenyl, dihydroxydiphenylsulfone, etc., and these may be used in combination of two or more. Can be.

However, in the case of polyethylene naphthalate having a polyethylene-2,6-naphthalate unit content of less than the above range or having an intrinsic viscosity of less than the above range, the high strength and high Young's modulus specific to the polyethylene naphthalate polymer are reduced. It is difficult to obtain, and the strength and toughness of the monofilament itself tend to be significantly reduced. Further, when a polymer having a terminal carboxyl group concentration exceeding the above range is used, hydrolysis, which is a typical drawback of polyester, is promoted, the intrinsic viscosity is substantially reduced, and operability such as breakage of stretch is deteriorated. Not only remarkably develops, but also the strength and toughness of the obtained monofilament tend to be greatly reduced.

That is, by using the above-mentioned polyethylene-2,6-naphthalate unit, the intrinsic viscosity and the polyethylene naphthalate polymer satisfying the terminal carboxyl group concentration, the high Young's modulus and high strength required for industrial materials are satisfied. A polyester monofilament can be obtained.

[0019] That is, polyethylene naphthalate monofilaments of the present invention has a Young's modulus measured according to JISL1013 is 8000 N / mm ² or more, preferably 10000 N / mm ² or more, more preferably 1500
It is 0 N / mm ² or more, and exhibits unprecedented excellent properties such as a dry heat shrinkage at 180 ° C. of 10% or less, preferably 5% or less, measured according to JIS L1013.

When the Young's modulus is less than the above range, it is at a level substantially equal to the maximum Young's modulus expressed by the conventional polyethylene terephthalate monofilament.
Not only is it not possible to obtain the advantages of a polyethylene naphthalate monofilament, but it is not preferable because it cannot meet the demand for a high Young's modulus represented by cable members.

That is, if the Young's modulus is 8000 N / mm ² or more, it is possible to sufficiently respond to the recent demand for industrial materials that could not be reached by polyethylene terephthalate monofilament, and to use various industrial materials. It can be easily deployed.

When the dry heat shrinkage at 180 ° C. exceeds the above range, the dimensions of the monofilament after high-order processing at 180 ° C. or more greatly change, so that not only is it difficult to design the dimensions after processing. However, it is not preferable because the production efficiency of high-order processing is reduced.

That is, the dry heat shrinkage at 180 ° C. is 10
% Or less, it is easy to easily design the dimension of the processed product in the high-order processing, and since the processed product can be produced using a small amount of monofilament, the production efficiency of the high-order processing is extremely improved. is there.

The polyethylene naphthalate polymer used in the present invention includes titanium oxide, silicon oxide, calcium carbonate, and the like as long as the object of the present invention is not impaired.
Inorganic particles such as magnesium carbonate, barium carbonate, barium sulfate, calcium sulfate, barium phosphate, lithium phosphate, calcium phosphate, magnesium phosphate, aluminum oxide, zirconia, lithium fluoride, kaolin, and talc, heat-resistant agents, weathering agents, and light-fasting agents , Hydrolysis stabilizers, UV inhibitors, antioxidants, antistatic agents, leveling agents, waxes,
Known additive components such as a silicone oil, a surfactant, a dye, and a pigment can be arbitrarily added as needed.

Furthermore, polyethylene naphthalate polymers include polyethylene terephthalate, polymethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polymethylene naphthalate, polybutylene naphthalate, and polypropylene naphthalate, as long as the object of the present invention is not impaired. Polyester such as phthalate or a copolymer or blend of two or more thereof, polyamide such as nylon 6, nylon 66, nylon 6.12, nylon 12, nylon 6.10, nylon 10, or copolymer or blend of two or more thereof Polyolefins such as polypropylene, low density and high density polyethylene, syndiotactic or atactic or isotactic polystyrene, polyphenylene sulfide Polysulfide, polystyrene-polybutadiene-polystyrene block copolymers, styrene-based thermoplastic elastomers such as polystyrene-polyisoprene-polystyrene block copolymers, and blends of olefin-based rubbers such as ethylene-propylene-diethylene copolymer with polyolefins such as polypropylene or ethylene. Polyolefin-based thermoplastic elastomer, polyurethane-based thermoplastic elastomer, polyester-based thermoplastic elastomer, fluoro-rubber-based thermoplastic elastomer, polyetherester, polyurethane, polycarbonate, polyarylate,
Fluororesins such as ethylene tetrafluoroethylene and polyvinylidene fluoride, and other thermoplastic resins such as silicone resins can be used by blending at 15% by weight or less as necessary.

The polyethylene naphthalate monofilament of the present invention has a diameter of 0.05 to 4.00 mm, particularly 0.20 to 2.00 mm, and a tensile strength of 3.0 cN / dt.
ex, more preferably 4.0 cN / dtex or more, and the tensile elongation is more preferably 5% or more, especially 10% or more.

Here, the tensile strength is 3.0 cN / dtex.
If the elongation is less than 5% and the tensile elongation is less than 5%, the brittle fracture and toughness of the monofilament are low, so that the necessary minimum elongation of the industrial material cannot be maintained. Become.

That is, the tensile strength is 3.0 cN / dtex.
As described above, a polyethylene naphthalate monofilament having a tensile elongation of 5% or more satisfies the minimum required properties and can be easily developed into industrial materials.

The polyethylene naphthalate monofilament of the present invention exhibits suitable performance as a monofilament for industrial materials by setting the diameter in the above range.

The cross-sectional shape of the polyethylene naphthalate monofilament of the present invention is not particularly limited, and may be, for example, a circle, an ellipse, a polygon such as a triangle, a square, or a hexagon, a star, a ten, a Y, or a H. Examples include irregular cross-sections such as a shape, a petal shape, and a hat shape, and a hollow shape. These shapes may be partially modified or synthesized. When used for industrial materials, these various cross-sectional shapes may be combined.

The polyethylene naphthalate monofilament of the present invention contains at least 85 mol% of ethylene-2,6-naphthalate units, has an intrinsic viscosity of at least 0.5 and a terminal carboxyl group concentration of at most 40 equivalents / t. Unstretched yarn melt extruded from a melt spinning machine,
After cooling with a cooling solvent having a temperature of (glass transition point of polymer −30 ° C.) to (glass transition point of polymer + 30 ° C.),
It can be manufactured by a method in which the film is stretched so that the total stretching ratio becomes 5.0 times or more, and then heat-treated under a 0.7 to 1.0 times relaxation or constant length ratio.

That is, when the temperature of the cooling solvent is lower than the above range, the undrawn yarn meanders in the cooling solvent, thereby causing cooling spots and diameter spots in the length direction of the undrawn yarn. In this case, productivity is deteriorated due to occurrence of stretching breakage or the like, which is not preferable.

If the temperature of the cooling solvent exceeds the above range, the undrawn yarn is not sufficiently and uniformly cooled in the length direction, and it is difficult to stabilize the drawing break or drawing point in the drawing step, thereby increasing the productivity. Not only worsens, but the cooling solvent is too hot, which promotes unsafe conditions such as burns,
In addition, the amount of volatile components in the cooling solvent increases, which leads to deterioration of the environment in the manufacturing plant, which is not preferable.

That is, the temperature of the cooling solvent is not less than (glass transition point of polymer−30 ° C.) (glass transition point of polymer +
By setting the temperature to 30 ° C. or lower, the undrawn yarn can be uniformly cooled in the length direction without meandering in the cooling solvent, so that problems such as breakage in drawing are reduced, and the production plant Because the environment inside the building does not deteriorate and there is no need for large capital investment, production efficiency is significantly improved.

The cooling solvent used in the present invention is not particularly limited as long as it is a liquid having a boiling point of 95 ° C. or higher, and examples thereof include water, organic solvents, polyethylene glycol and surfactants. Preferably, water or polyethylene glycol is used.

In the stretching step of the production method of the present invention,
It is important that the total draw ratio is 5.0 times or more, particularly 5.5 times or more, and multi-stage drawing in which the total draw ratio is less than 5.0 times, that is, the initial draw ratio is at least 5.0 times. If the ratio is less than twice, the stretching point of the monofilament in the stretching step becomes an unstable region, sufficient orientation cannot be performed in the fiber axis direction, and stretching breakage due to the unstable stretching point of the monofilament tends to occur. become. In addition,
Since the minimum strength and elongation and Young's modulus required as industrial materials cannot be maintained, it is not preferable because it is difficult to develop them into various industrial materials.

The number of stretching steps is not particularly limited, but is preferably one to three. That is, 4
Although it is possible to draw more than one step, as the number of steps increases, the equipment for the monofilament drawing step becomes longer, which increases capital investment costs and process maintenance costs, and tends to promote drawing breaks in multi-step drawing. This is not practically desirable because it causes a decrease in efficiency and an increase in production cost.

In other words, the monofilament stretching point is uniformly stabilized by performing single-stage or multi-stage stretching in which the total stretching ratio is 5.0 times or more, and the minimum strong elongation and Young's modulus required for industrial materials are reduced. Since it can be maintained, the obtained monofilament can be easily applied to various industrial materials.

Further, the stretching temperature is preferably a temperature of (glass transition point of polymer + 20 ° C.) to (melting point of polymer), and most preferably 120 to 200 ° C.

In the production method of the present invention, heat treatment is performed to maintain a low heat shrinkage rate following the above stretching, and the heat treatment magnification in this case is 0.7 even when the relaxation heat treatment temperature is added. It is necessary to set the length to a fixed length or a relaxation condition of up to 1.0 times.

In other words, if the heat treatment magnification is less than the above range, the monofilament sags in the heat treatment apparatus and flaws or breakage (yarn breakage) occur due to contact with the inside of the apparatus, and the quality of the monofilament deteriorates. Not preferred. On the other hand, if the heat treatment magnification exceeds the above range and becomes a tension state, the stretching distortion cannot be reduced unless the heat treatment temperature is excessively increased, and the low heat shrinkage of the present invention of 180 ° C. % Is not preferable because it is difficult to realize the characteristics of less than 10%.

That is, the relaxation heat treatment magnification is 0.7 to 1.0.
It is optimal to reduce the stretching strain of the obtained monofilament by selecting the optimal point of the heat treatment temperature as a constant-length or relaxation heat treatment in the range of twice, and furthermore, to simultaneously increase the high Young's modulus and low heat shrinkage of the monofilament Since the monofilament can be provided together, and the workability in the high-order processing of the monofilament is greatly improved, it can be easily applied to various industrial materials.

Here, a gas such as air or nitrogen or a liquid solvent such as an organic solvent or polyethylene glycol can be used as a heat medium for the heat treatment.
Among them, air and polyethylene glycol are preferably used.

The heat treatment temperature is preferably from (glass transition point of polymer + 20 ° C.) to (melting point of polymer + 20 ° C.). (Polymer melting point +
Temperatures in the range (20 ° C.) are most preferred.

According to the production method of the present invention, the desired and excellent monofilament equipment can be used at low cost and efficiently without any extra capital investment or drastic changes in the yarn production conditions. Polyethylene naphthalate monofilaments with properties can be produced.

The polyethylene naphthalate monofilament of the present invention thus obtained can easily be subjected to higher-order processing, and can be used as various industrial materials.

The various industrial materials are not particularly limited, but include, for example, industrial fabrics or knitted fabrics such as papermaking, canvas, felt, filter, screen gauze, brush tips of toothbrushes, and industrial brushes. , Fishery materials such as gugs, longlines, fishing nets, guts such as tennis and badminton, instrument strings such as koto, guitar strings,
Agricultural uses such as tensioning and brushing, and cable members such as discarded wires, stranded wires, lead wires, cords, ropes, and communication cable reinforcing wires are included.

Among the above-mentioned industrial materials, they can be used particularly effectively as communication cable members. In other words, in the optical fiber communication cable, a reinforcing wire or a tension member used for the purpose of reinforcing the optical fiber and the like,
Further, there are intervening wires used for filling the gaps in the optical fiber and tear lines used to peel off the outer coating of the cable.The polyethylene naphthalate monofilament of the present invention includes these reinforcing wires, intervening wires. And can be effectively developed for applications such as tear lines.

[0049]

EXAMPLES The present invention will be further described with reference to the following examples, but the present invention is not limited to these examples. The methods for measuring the various properties of the polyethylene naphthalate monofilament of the present invention described above and below were performed according to the following methods. [Intrinsic viscosity] A precisely weighed monofilament sample or chip material was dissolved in orthochlorophenol solution,
Viscosity measurement value measured in an atmosphere of ° C. [Terminal carboxyl group] A precisely weighed monofilament sample or chip raw material is dissolved in an orthocresol solution,
A measured value obtained by adding an appropriate amount of dichloromethane to the solution and then using a 0.02 N methanol solution of potassium hydroxide. [Diameter (mm)] Digital micrometer (MITU
Average value measured five times in the length direction of the monofilament using a product (TOYO). [Tensile strength and elongation (cN / dtex,%)] JIS L10
13 Measured in accordance with 7.5.1. [Young's modulus (N / mm ² )] JIS L1013
It was measured according to 7.10. [Dry heat shrinkage (%)] JIS L1013 7.15
(2) Dry heat shrinkage rate Measured according to the method B (filament shrinkage rate). [Spinnability] The spinnability was determined based on the following two levels.

・: Monofilament can be drawn uniformly and without any breakage.

X: The monofilament is not uniformly stretched, and the productivity such as breakage of the stretch is poor, so that production cannot be performed.

The raw materials used in Examples and Comparative Examples are as follows. [Raw material A] intrinsic viscosity 0.83, terminal carboxyl group 11
Equivalent / t of polyethylene naphthalate resin (PN550 manufactured by Toyobo Co., Ltd., glass transition point: 123 ° C., melting point: 270
° C). [Raw material B] intrinsic viscosity 1.07, terminal carboxyl group 14
Equivalent / t of polyethylene terephthalate resin (T750M manufactured by Toray Industries, glass transition point: 75 ° C, melting point: 255)
° C). Example 1 Raw material A was melted at 320 ° C. by a usual extruder spinning machine, spun out from a die having a diameter of 1.0 mm via a gear pump, and cooled in a polyethylene glycol cooling bath having a cooling solvent temperature of 95 ° C.

The obtained undrawn yarn is drawn at 140 ° C. by one step at 6.0 times, then heat-relaxed at 200 ° C. by 0.95 times and wound at a speed of 150 m / min to obtain a polyethylene naphthalate monofilament. Manufactured.

Table 1 shows the results of evaluating the properties of the obtained polyethylene naphthalate monofilament. Example 2 Raw material A was melted at 320 ° C. using a normal extruder type spinning machine, and the diameter was 2.5 m through a gear pump.
It was spun from a mφ nozzle and cooled in a polyethylene glycol cooling bath at a cooling solvent temperature of 95 ° C.

The obtained unstretched yarn was 140 times at 6.0 ° C.
After step stretching, heat-relax at 0.95 times at 240 ° C,
A polyethylene naphthalate monofilament was produced by winding at a speed of 110 m / min.

Table 1 shows the results of evaluating the properties of the obtained polyethylene naphthalate monofilament. Example 3 Raw material A was melted at 320 ° C. using a normal extruder type spinning machine, and the diameter was 3.0 m via a gear pump.
It was spun from a mφ nozzle and cooled in a polyethylene glycol cooling bath at a cooling solvent temperature of 95 ° C.

The obtained undrawn yarn is drawn at 140 ° C. by 6.0 times, then relaxed at 240 ° C. by 0.95 times and wound at a speed of 70 m / min to form a polyethylene naphthalate monofilament. Manufactured.

Table 1 shows the results of evaluating the properties of the obtained polyethylene naphthalate monofilament. Example 4 Raw material A was melted at 320 ° C. using a normal extruder type spinning machine, and the diameter was 4.0 m via a gear pump.
It was spun from a mφ nozzle and cooled in a polyethylene glycol cooling bath at a cooling solvent temperature of 95 ° C.

The obtained undrawn yarn is drawn at 160 ° C. by one step at 6.0 times, then heat-relaxed at 240 ° C. by 0.95 times and wound at a speed of 60 m / min to obtain a polyethylene naphthalate monofilament. Manufactured.

Table 1 shows the results of evaluating the properties of the obtained polyethylene naphthalate monofilament. Example 5 Raw material A was melted at 320 ° C. using a normal extruder type spinning machine, and the diameter was 12 mm through a gear pump.
It was spun from a φ die and cooled in a polyethylene glycol cooling bath at a cooling solvent temperature of 95 ° C.

The obtained undrawn yarn is drawn at 140 ° C. for one step at 6.0 times, then heat-relaxed at 200 ° C. at 0.97 times, and wound at a speed of 30 m / min to obtain a polyethylene naphthalate monofilament. Manufactured.

Table 1 shows the results of evaluating the properties of the obtained polyethylene naphthalate monofilament. [Example 6] Polyethylene was produced in the same manner as in Example 1 except that the obtained undrawn yarn was drawn 5.5 times at 140 ° C and further changed to two-step drawing at 1.18 times at 180 ° C. A naphthalate monofilament was manufactured.

Table 1 shows the results of evaluating the properties of the obtained polyethylene naphthalate monofilament. [Example 7] Except that the obtained unstretched yarn was stretched 5.5 times at 140 ° C, further stretched at 200 ° C to 1.45 times, and then changed to a relaxation heat treatment at 240 ° C. Example 1
A polyethylene naphthalate monofilament was produced in the same manner as described above.

Table 1 shows the characteristic evaluation results of the obtained polyethylene naphthalate monofilament.

[0065]

[Table 1] [Comparative Example 1] The same method as in Example 1 was used, except that the obtained undrawn yarn was stretched 4.0 times at 140 ° C for one step, and then changed to a relaxation heat treatment at 240 ° C to 0.95 times. Polyethylene naphthalate monofilament was produced.

In this case, a uniform monofilament could not be obtained due to an unstable drawing point.
Table 2 shows the results of evaluating the characteristics. Comparative Example 2 A polyethylene naphthalate monofilament was produced in the same manner as in Example 1 except that the obtained undrawn yarn was subjected to a heat treatment for relaxation at 200 ° C. by a factor of 0.65.

However, in this case, a sample could not be obtained because the drawn yarn came into contact with the inside of the relaxation heat treatment step. . Comparative Example 3 Example 1 except that the obtained undrawn yarn was changed to be cooled in a water cooling bath at a cooling solvent temperature of 60 ° C.
A polyethylene naphthalate monofilament was produced in the same manner as described above.

However, in this case, the sample could not be obtained because the undrawn yarn became severely meandered in the cooling bath and the drawing was frequently broken. [Comparative Example 4] The obtained undrawn yarn was cooled to a cooling medium temperature of 155 ° C.
A polyethylene naphthalate monofilament was produced in the same manner as in Example 1 except that the cooling was performed in a polyethylene glycol cooling bath.

However, in this case, a sample could not be obtained because the surroundings of the cooling bath were full of volatile components of the cooling solvent. Comparative Example 5 A polyethylene naphthalate monofilament was produced in the same manner as in Example 1, except that the obtained undrawn yarn was not subjected to relaxation heat treatment.

Table 2 shows the results of evaluating the properties of the obtained polyethylene naphthalate monofilament. [Comparative Example 6] Raw material B was melted at 280 ° C with a normal extruder-type spinning machine, and the diameter was 0.7 m via a gear pump.
It was spun from a mφ nozzle and cooled in a water cooling bath at a cooling solvent temperature of 70 ° C.

The undrawn yarn obtained was 3.0 times at 93 ° C.
After stretching in two stages at 200 ° C. and two-stage stretching at 1.93 times, the film was subjected to a relaxation heat treatment at 250 ° C. to 0.75 times, and a speed of 150
By winding at m / min, a polyethylene terephthalate monofilament was produced.

Table 2 shows the results of evaluating the properties of the obtained polyethylene terephthalate monofilament.

[0073]

[Table 2]

[0074]

As described above, the polyethylene naphthalate monofilament of the present invention has a property of high Young's modulus and low heat shrinkage which cannot be exhibited by polyethylene terephthalate at all, and it is easy to increase the Because it can be processed, many industrial materials, such as industrial fabrics or knitted fabrics such as papermaking, canvas, felt, filters, screen gauze, bristles of toothbrushes, brushes such as industrial brushes, tex, longlines, fishing nets, etc. Fishery materials, gut such as tennis and badminton, instrument strings such as koto strings, guitar strings, agricultural uses such as zhang wires, brush cutters,
It can be applied to many fields such as cable members such as discarded wires, stranded wires, lead wires, cords, ropes, and communication cable reinforcing wires.

Further, according to the production method of the present invention, polyethylene naphthalate monofilaments having the above-mentioned excellent characteristics can be produced efficiently at low cost without extra capital investment by ordinary monofilament production equipment. be able to.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H050 AA15 AB42X 3B153 AA01 BB01 CC21 CC31 CC32 FF08 FF23 FF24 FF40 4L035 BB31 BB58 BB79 BB81 BB85 BB91 CC02 CC07 CC09 DD14 EE01 EE08 EE20 FF01 HH10

Claims (7)

[Claims] 1. A monofilament comprising polyethylene naphthalate having an ethylene-2,6-naphthalate unit of 85 mol% or more, an intrinsic viscosity of 0.5 or more, and a terminal carboxyl group concentration of 40 equivalents / t or less, JIS
Young's modulus measured according to L1013 is 8000 N /
mm ² or more, 18 measured according to JIS L1013
A polyester monofilament having a dry heat shrinkage at 0 ° C. of 10% or less. 2. The polyester monofilament according to claim 1, wherein the fiber diameter is 0.05 to 4.00 mm. 3. The polyester monofilament according to claim 1, wherein a tensile strength measured according to JIS L1013 is 3.0 cN / dtex or more, and a tensile elongation is 5% or more. 4. A polyethylene naphthalate containing 85 mol% or more of ethylene-2,6-naphthalate units, having an intrinsic viscosity of 0.5 or more and a terminal carboxyl group concentration of 40 equivalents / t or less, is melt-extruded from a melt spinning machine. The drawn undrawn yarn is
After cooling with a cooling solvent having a temperature of (glass transition point of polymer −30 ° C.) to (glass transition point of polymer + 30 ° C.),
The film is stretched so that the total stretching ratio becomes 5.0 times or more, and then heat-treated under a 0.7 to 1.0 times relaxation or constant length ratio. 3. The method for producing a polyester monofilament according to item 1. 5. An industrial material comprising the polyester monofilament according to any one of claims 1 to 3. 6. The industrial material according to claim 5, wherein said industrial material is a cable member. 7. The industrial material according to claim 6, wherein the cable member is an optical fiber cable.