JPH07145511A - Polyester monofilament - Google Patents

Abstract

PURPOSE:To obtain polyester monofilament suitable as a papermaking canvas excellent in hydrolytic and flexing abrasion resistances. CONSTITUTION:This polyester monofilament comprises a composition containing polytetrafluoroethylene resin powder having <=5mum maximum particle diameter and <=1mum average particle diameter in an amount of 0.1-10wt.% based on the whole in polyethylene terephthalate having >=0.6 intrinsic viscosity and $10g equiv./10<6>g terminal carboxyl group concentration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester monofilament which is excellent in hydrolysis resistance and flex abrasion resistance and is suitable for papermaking canvas.

[0002]

2. Description of the Related Art Polyethylene terephthalate has strength,
It has excellent properties such as chemical resistance, heat resistance, weather resistance, and electrical insulation, and is widely used in industrial applications.
Among the industrial applications, monofilaments used especially for papermaking machines are woven into a canvas cloth and used as a belt for continuously transporting a paper sheet in a wet state, which is made by papermaking, by pressing it on a drying cylinder and drying it. , High hydrolysis resistance and bending abrasion resistance are required.

As a method of increasing the hydrolysis resistance of polyester filaments, a method of reducing the terminal carboxyl group concentration of polyester in advance is known, and a method of adding an epoxy compound (Japanese Patent Publication No. 44-27911).
JP-A-54-6051), a method of adding a carbodiimide compound (JP-B-1-15604, JP-A-3-104919, etc.), a method of adding a carbodiimide compound and a fluorine compound (JP-A-4-149268). No.) etc. have been proposed. According to these methods, the hydrolysis resistance is improved to some extent, but there is a problem that the flexing abrasion resistance is not sufficient.

On the other hand, as a method for increasing the flex wear resistance,
A method of adding metal particles (JP-A-3-76813), a method of coating the surface of a monofilament with a silicon compound (JP-A-3-249273, 3-269169), and a core-sheath composite yarn of polyester and nylon. Method (JP-A-2
No. 145894) has been proposed. According to these methods, although the flexing abrasion resistance is improved to some extent, there are problems that not only the hydrolysis resistance is insufficient, but also the contact portion of the belt such as the roller surface is abraded.

As a method of imparting lubricity to polyester, a method of adding a fluororesin having a particle size of 50 μm or less (Japanese Patent Laid-Open No. 54-124055) has been proposed. According to this method, the lubricity is improved to some extent, but when the monofilament having a small diameter is used, there is a problem that the flexing abrasion resistance is not sufficient.

[0006]

DISCLOSURE OF THE INVENTION The present invention is intended to provide a polyester monofilament having excellent hydrolysis resistance and flex abrasion resistance.

[0007]

Means for Solving the Problems The present invention is to solve the above problems, and its gist is to provide polyethylene terephthalate (PET) with an intrinsic viscosity of 0.6 or more and a terminal carboxyl group concentration of 10 g equivalent / 10 ⁶ g or less, A polyester monofilament made of a composition containing 0.1 to 10% by weight of polytetrafluoroethylene resin (PTFE) powder having a maximum particle size of 5 μm or less and an average particle size of 1 μm or less based on the whole powder.

The present invention will be described in detail below. In the present invention, PET is preferably a homopolymer, but may contain a copolymerization component as long as the effects of the present invention are not impaired. Specific examples of the copolymerization component include isophthalic acid, succinic acid, adipic acid, suberic acid, dodecanedioic acid, azelaic acid, sebacic acid, 1,3-
Propanediol, 1,4-butanediol, 1,6-hexanediol, hydroquinone, 4,4'-dihydroxydiphenyl, bisphenol A, 1,4-naphthalenedicarboxylic acid, 2,4-naphthalenedicarboxylic acid, 2,6- Naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, 3-hydroxypropanoic acid, 4-hydroxybutanoic acid, ε-caprolactone, 4-hydroxybenzoic acid, 2-hydroxy-6-
Naphthoic acid and the like can be mentioned. Further, an unsaturated dicarboxylic acid having an intermolecular crosslinkable structure, an unsaturated diol, and a trifunctional or higher functional monomer component may be copolymerized,
Various additives may be included.

The monofilament of the present invention has an intrinsic viscosity
0.6 or more, preferably 0.7 to 0.9, and a terminal carboxyl group concentration of 10 g equivalent / 10 ⁶ g or less, preferably 5 g equivalent / 10
Consists of less than ⁶ g PET. When the intrinsic viscosity is less than 0.6, mechanical properties such as tensile strength are deteriorated, which is not preferable. Also, the terminal carboxyl group concentration is 10 g equivalent / 10
If it exceeds ⁶ g, hydrolysis resistance is not sufficient.

The terminal carboxyl group concentration is 10 g equivalent / 10 ⁶ g
To the following, in any step up to the melt spinning step,
A carbodiimide compound such as 2,6,2 ′, 6′-tetraisopropyldiphenylcarbodiimide (TPC) and a terminal carboxyl group blocking agent such as an epoxy compound such as phenylglycidyl ether may be added and reacted. For example, the terminal carboxyl group concentration is 20 g equivalent / 10 ⁶ g
The following PET is used, and TPC is 0.1 to 3.
It may be added by 0% by weight and melt-spun by using an extruder.

The monofilament of the present invention has a maximum particle diameter of 5 μm or less and an average particle diameter of 1 μm or less.
It is necessary to contain the E powder in an amount of 0.1 to 10% by weight based on the whole. If the maximum particle size of PTFE powder exceeds 5 μm, filter clogging occurs during spinning and the average particle size is 1 μm.
If it exceeds, there are problems such as frequent yarn breakage, which is not preferable. Further, if the content of the PTFE powder is less than 0.1% by weight, the effect of improving the bending wear resistance is insufficient, and the content is 10% by weight.
If it exceeds, mechanical strength and other mechanical properties will deteriorate, which is not preferable.

The PTFE powder can be blended with the polyester at any stage from the polymerization to the spinning process, and may be blended as a master chip during spinning.

[0013]

The monofilament of the present invention has excellent resistance to hydrolysis because it has a low concentration of terminal carboxyl groups, and since it contains fine PTFE particles having excellent lubricity, it has excellent resistance to flexing wear.

[0014]

EXAMPLES Next, the present invention will be described in detail with reference to examples. In addition, the measuring method of the characteristic value in an Example is as follows. (1) Intrinsic viscosity [η] It was determined from the solution viscosity measured at a temperature of 20 ° C using an equal weight mixture of phenol and ethane tetrachloride as a solvent. (2) Tensile strength Tensilon UTM-4-100 type manufactured by Orientec Co., Ltd. was used for measurement at a sample length of 10 cm and a tensile speed of 10 cm / min. (3) Hydrolysis resistance [η] and tensile strength of a sample treated with saturated steam at 130 ° C for 15 days in an autoclave were measured and evaluated by comparing with the value before treatment. (The value after processing is the same as the value before processing.
70% or more pass. ) (4) Bending abrasion resistance With a yarn abrasion tester used in JIS L 1095 7.10.2B method, a load of 0.2 g / d is applied to the monofilament, the friction speed is 60 times / min, the friction angle is 110 degrees, The test was conducted under the conditions of a round trip distance of 2.5 cm, a sample length of 20 cm, a friction element and a diameter of 1.0 mm hard steel, and the number of times until the filament was cut was measured. (Passed 6000 times or more.)

Example 1 A slurry of terephthalic acid and ethylene glycol in a molar ratio of 1 / 1.6 was continuously fed to an esterification reaction vessel containing bis (β-hydroxyethyl) terephthalate and its low polymer (BHET). , Temperature 250 ℃, pressure 0.05kg /
Perform the esterification reaction under the conditions of cm ² and residence time of 8 hours,
BHET having an esterification reaction rate of 95% was continuously obtained. 50 kg of this BHET was transferred to a polymerization tank and heated to 280 ° C., and 2 × 10 ⁻⁴ mol of antimony trioxide as a catalyst was added to 1 mol of the acid component constituting the polyester, and the average particle size was 0.3 μm.
PTFE powder with a maximum particle size of 2 μm (KTL-500F manufactured by Kitamura)
30% by weight ethylene glycol slurry was added in an amount such that the amount of PTFE was 5% by weight of the resulting polyester composition. Then, the pressure was gradually reduced, and the polycondensation reaction was finally performed at 280 ° C. under a reduced pressure of 0.1 torr for 2.5 hours to obtain a polyester chip of [η] 0.68. 180 ° C under reduced pressure
By solid-state polymerization in (1), solid-state polymerized polyester chips having [η] 0.85 and terminal carboxyl group concentration of 15.0 g equivalent / 10 ⁶ g were obtained. 2% by weight of TPC was added to the obtained polyester chips and the mixture was supplied to an extruder type melt spinning machine, and a spinneret (diameter 90 mm) having a hole diameter of 2.4 mm and 6 holes was used, a speed of 33 m / min, and a temperature of 310 ° C. Was spun, quenched in a water bath at 80 ° C., and divided into 6 to obtain undrawn yarn. The obtained undrawn yarn was drawn 5.7 times and heat-treated at 295 ° C. to obtain a monofilament having a diameter of 0.4 mm.

Examples 2 to 7 In Example 1, the particle size and the addition amount of the PTFE powder are shown in Table 1.
Example 1 was carried out in the same manner as in Example 1 except that the changes were made as shown in FIG.

Examples 8 to 9 The procedure of Example 1 was repeated, except that the amount of TPC added was changed as shown in Table 1.

Example 10 The procedure of Example 1 was repeated, except that phenylglycidyl ether was used instead of TPC.

Example 11 The procedure of Example 1 was repeated, except that PET having an [η] of 0.65 was used.

Comparative Examples 1 to 4 In Example 1, the particle size and the addition amount of the PTFE powder are shown in Table 1.
The same procedure as in Example 1 was carried out except that the changes were made as shown in FIG.

Comparative Example 5 Example 1 was repeated except that the amount of TPC added was changed as shown in Table 1.

Comparative Example 6 The procedure of Example 1 was repeated, except that PET having [η] 0.55 was used.

Table 1 shows the results obtained by measuring the hydrolysis resistance and flex wear resistance of the monofilaments obtained in the above Examples and Comparative Examples.

[0024]

[Table 1]

[0025]

Industrial Applicability According to the present invention, there is provided a polyester monofilament which is excellent in hydrolysis resistance and bending abrasion resistance and is suitable for papermaking canvas. Further, the monofilament of the present invention can be manufactured with good operability.

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Claims (1)

[Claims] 1. Polytetrafluoroethylene resin powder having a maximum particle size of 5 μm or less and an average particle size of 1 μm or less is added to polyethylene terephthalate having an intrinsic viscosity of 0.6 or more and a terminal carboxyl group concentration of 10 g equivalent / 10 ⁶ g or less based on the total amount of 0.1. ~Ten
A polyester monofilament composed of a composition containing 100% by weight.