JPH09294506A - Polyester fiber for fishery material, its production and fishing net - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester fiber composed of a high-density core-sheath conjugate fiber having excellent hydrolysis resistance and aminolysis resistance and useful as a fishery material such as fishing net. SOLUTION: This polyester fiber is a core-sheath conjugate fiber produced by the melt-spinning of a core layer material and a sheath layer material and the drawing of the spun fiber. The core layer material is a mixture having a specific gravity of >=1.8 and produced by compounding a polyester with fine powder of a metal and/or a metallic compound having a specific gravity of 4-22, a specific surface area of <=11m<2> /g, an average particle diameter of <=1μm and a maximum particle diameter of <=2μm and the sheath layer material is a mixture produced by compounding a polyethelene terephthalate or a polyester composed mainly of the polyethylene terephthalate and having a carboxyl terminal group content of >=20eq/t with 0.3-2.0wt.% of a monocarbodiimide compound and 0.03-0.50wt.% of N,N'-bis[3-(3,5-di-t- butyl-4-hydroxyphenyl)propionyl]hydrazine. The carboxyl terminal group content of the sheath layer is <=5eq/t and conjugate fiber has a tensile strength of >=4.2g/d, a tensile elongation at break of >=15%, a knot strength of >=3.0g/d and a specific gravity of >=1.7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester fiber for a marine material, which comprises a high specific gravity core / sheath composite fiber having excellent hydrolysis resistance and amine decomposition resistance, a method for producing the same, and a fishing net.

[0002]

BACKGROUND OF THE INVENTION Polyester fibers have various excellent properties and are also used as fibers for marine products such as fishing nets (see, for example, Japanese Patent Publication No. 58-38530).

Generally, after using the fishing net, it is dried on the beach, the seafood attached to the fishing net is decomposed by corrosion, and then washed and dried.
Will use again. Then, when the seafood is decomposed by corrosion, a sheet is put on the dried fishing net, the inside of the sheet is kept in a high temperature and high humidity state, the decomposition of the seafood is promoted, and the fishing net washing process is shortened and simplified. There is. At that time, when polyester fiber is used as the constituent thread of the net, the fishing net undergoes amine decomposition and hydrolysis to deteriorate due to the synergistic effect of ammonia, water and heat generated as decomposition components of seafood, and the net strength is increased. There was a problem that it decreased and it became impossible to use for a long time.

Polyester fiber is a synthetic fiber having a relatively large specific gravity, but a higher specific gravity is desired in order to improve the shape retention of the fishing net against tidal current because the sedimentation speed in water is high. ing.

Conventionally, various methods have been proposed for obtaining a synthetic fiber having a high specific gravity by containing a powder having a high specific gravity. However, the strength of the obtained fiber is lowered, and the high specific gravity and the high required for a fishing net are required. It was difficult to obtain strong fibers.

As a moist heat resistant polyester filament used for papermaking canvas and the like, a monocarbodiimide compound and N, N'-bis [3- (3,5-di-t-
A butyl-4-hydroxyphenyl) propionyl] hydrazine-containing polyester filament having a low carboxyl end group content is known, but a polyester fiber having high specific gravity and resistance to moist heat is not known.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a polyester fiber for marine products having excellent amine decomposition resistance and hydrolysis resistance, high specific gravity and high strength, a method for producing the same, and a fishing net using the fiber. Is to provide.

[0008]

The present invention solves the above-mentioned problems, and the gist is as follows. 1. As a core layer, polyester has a specific gravity of 4 to 22, a specific surface area of 11
A mixture of fine powder of metal and / or metal compound having a particle size of m ² / g or less, an average particle size of 1 μm or less, and a maximum particle size of 2 μm or less and a specific gravity of 1.8 or more, and a carboxyl group as a sheath layer.
Polyethylene terephthalate of 20 eq / t or less or polyester mainly composed of this and a monocarbodiimide compound 0.3
Up to 2.0% by weight and N, N'-bis [3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionyl] hydrazine (hereinafter abbreviated as hydrazine-based hindered phenol) 0.03 to 0.50% by weight of the mixture was melt-spun and stretched to obtain a core-sheath composite fiber. The amount of carboxyl end groups in the sheath layer is 5 eq / t or less, linear strength is 4.2 g / d or more, linear cutting elongation is 15% or more, knot strength is 3.0 g / d or more, specific gravity
Polyester fiber for marine products characterized by being 1.7 or more. 2. The method for producing a polyester fiber for marine products according to the above 1, characterized in that the following steps are sequentially performed. (a) Polyester with a specific gravity of 4 to 22, a specific surface area of 11 m ² / g or less,
Metals with an average particle size of 1 μm or less and a maximum particle size of 2 μm or less and /
Or evenly disperse a fine powder of a metal compound to obtain a specific gravity of 1.8.
The step of obtaining the above core layer material, (b) a monocarbodiimide compound on the polyethylene terephthalate having a carboxyl end group content of 20 eq / t or less or a polyester mainly composed of this
0.3 to 2.0% by weight and 0.03 to 0.50% by weight of hydrazine-based hindered phenol were added to form a sheath layer material, and composite melt spinning was performed with the above core layer material. When the carboxyl end group content of the sheath layer was 5 eq / t or less. , A step of obtaining a core-sheath composite unstretched fiber having a fiber specific gravity of 1.7 or more, (c) a core-sheath composite unstretched fiber is stretched, a linear strength of 4.2 g / d or more, a linear cutting elongation of 15% or more, and a knot strength of 3.0. The process of obtaining composite fibers with a specific gravity of 1.7 or more and g / d or more. 3. A fishing net braided using the polyester fiber for marine products as described in 1 above.

In the present invention, the amount of carboxyl end groups of the polyester is determined by dissolving the polyester in benzyl alcohol and titrating with 0.1N potassium hydroxide methanol solution. (The amount of carboxyl end groups in the sheath layer of the composite fiber is determined by eluting the polyester in the sheath layer with an equal weight mixed solvent of phenol and ethane tetrachloride, and removing the solvent by using the polyester as a sample by the above method. The strength and elongation are measured according to JIS L 1013 method.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

Fibers for marine products are required to have high strength as well as high specific gravity. The sheath layer is a portion that bears the strength of the fiber, and in the present invention, as the sheath layer, polyethylene terephthalate which expresses high strength by stretching treatment or a main component thereof, isophthalic acid, adipic acid, sebacic acid, 2,6- Naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-
A polyester containing a small amount of cyclohexanedimethanol as a copolymerization component is used.

Since the fibers for marine products are also required to have abrasion resistance, it is necessary to prevent peeling at the interface between the sheath layer and the core layer. A compatible polyester is used. Usually, the same polyester as that used for the sheath layer is used for the core layer.

The polyester used in the present invention preferably has a relative viscosity (measured at a concentration of 0.5 g / dl and a temperature of 20 ° C. using an equal weight mixture of phenol and ethane tetrachloride as a solvent) in the range of 1.40 to 1.75. When the relative viscosity of the polyester of the core layer is less than 1.40, the melt viscosity of the mixture is reduced by compounding the fine powder, and further, the viscosity is remarkably lowered by the remelting during spinning, which makes stable spinning difficult. Become. Further, if the relative viscosity of the sheath layer is less than 1.40, high-strength fibers cannot be obtained, and abrasion resistance also decreases. On the other hand, when the relative viscosity of polyester exceeds 1.75,
There is a problem that the surface of the fiber is roughened during the fiber formation process due to melting spots and poor fluidity of the molten polymer.When the melting temperature is raised to completely melt the polymer, thermal decomposition of the polymer occurs, resulting in high viscosity. There is a problem that the effect of the polymer is lost.

It is known that the carboxyl terminal group plays a catalytic role in the hydrolysis of polyester, and the hydrolysis proceeds by attack of water molecules on the ester bond portion. In addition, the amine decomposition proceeds by neutralizing the ammonia and the carboxyl terminal group at the initial stage of the reaction to generate an amide terminal group and a water molecule, and subsequently hydrolyzes the water molecule and an ester bond to proceed. That is, the degradation of polyester is greatly affected by the amount of terminal carboxyl groups.

Since a polymer having a smaller amount of carboxyl end groups has a slower hydrolysis rate, the amount of carboxyl end groups of the polyester for the sheath layer is 20 eq / t or less, preferably 5 to 19 eq / t.
It is necessary to Further, by satisfying this condition, the terminal blocking agent can finally reduce the amount of carboxyl terminal groups in the sheath layer of the filament to 5 eq / t or less. This is because when the carboxyl end group amount of the raw material polyester is 20 eq / t or more, the filament after spinning and drawing does not exhibit resistance to hydrolysis and amine decomposition,
Furthermore, in order to reduce the amount of carboxyl terminal groups in the sheath layer of the filament after spinning and drawing to 5 eq / t or less, it is necessary to add a large amount of terminal blocking agent, which is a disadvantage from an industrial viewpoint.

Such a polyester for the sheath layer can be obtained as follows. First, a prepolymer having a relative viscosity of 1.30 to 1.45 is obtained by a usual melt polymerization method.
Next, the pellets of this prepolymer are heated under reduced pressure or under the flow of an inert gas to carry out a solid phase polymerization reaction to obtain a polyester having a predetermined relative viscosity and a carboxyl terminal group amount.
If the relative viscosity of the prepolymer is not appropriate, the total polymerization time will be remarkably lengthened, or the amount of carboxyl terminal groups of the polyester after solid phase polymerization cannot be adjusted within a predetermined range. It is desirable that the relative viscosity be within the above range.

It is preferable to select the conditions of the solid phase polymerization so that the relative viscosity becomes about 0.10 to 0.50 higher than that of the prepolymer by the solid phase polymerization. This solid-state polymerization reduces the amount of carboxyl end groups of the polyester,
Impurities such as oligomers are removed.

0.3 to 2.0% by weight of a monocarbodiimide compound as an end-capping agent is added to the polyester for the sheath layer as described above and melt-spun, so that the amount of carboxyl end groups in the sheath layer of the composite fiber is 5 eq / t or less. It is necessary to do so. If the amount of carboxyl terminal groups in the sheath layer is more than 5 eq / t, the yarn quality will be remarkably deteriorated by the long-term wet heat treatment, and the target performance will not be expressed.

As the monocarbodiimide compound, those represented by the following general formula are preferably used. R ¹ —N ＝ C ＝ N—R ^{2 In the} formula, R ¹ and R ² are a phenyl group in which at least one of positions ² , 4, or 6 is substituted by a lower alkyl group.

Specific examples of such monocarbodiimide compounds include N, N'-bis (2,6-dimethylphenyl) carbodiimide, N, N'-bis (2,6-diethylphenyl) carbodiimide and N, N. ′ -Bis (2,6-diisopropylphenyl) carbodiimide, N, N′-bis (2
-Isopropylphenyl) carbodiimide and the like.

The addition amount of the monocarbodiimide compound is 0.3
It is necessary to set the content to about 2.0% by weight, and the target performance cannot be expressed unless this condition is satisfied. That is, if the amount added is less than 0.3% by weight, the blocking of the carboxyl end groups will be insufficient and the moist heat resistance will not be satisfied, and if it exceeds 2.0% by weight, the spinnability will deteriorate. The amount of the monocarbodiimide compound added is preferably such that the amount of carboxyl terminal groups in the sheath layer of the filament obtained by melt spinning becomes 5 eq / t or less and a small amount of unreacted monocarbodiimide compound remains.

The addition of the monocarbodiimide compound to the core layer can further improve the decomposition and deterioration resistance of the fiber. When the monocarbodiimide compound is added to the core layer, the addition amount is 0.3 to 2.0 as in the sheath layer.
Although it may be wt%, the target performance can be exhibited with a smaller amount of addition than the amount added to the sheath layer. this is,
This is because decomposition by water, heat or amine occurs preferentially from the sheath layer.

It is also preferable to add 0.02 to 1.00% by weight of the aromatic polycarbodiimide compound at the same time as adding the monocarbodiimide compound to the polyester. When the amount of the aromatic polycarbodiimide compound added is less than 0.02% by weight, it is difficult to develop the performance of the aromatic polycarbodiimide compound, and when it exceeds 1.00% by weight, melt viscosity increases during spinning, resulting in poor spinnability. Therefore, the addition amount is preferably in the above range.

As the aromatic polycarbodiimide compound, a compound in which carbodiimide units are linked in a chain to an aromatic ring and has an isopropyl group as a substituent on the aromatic ring is preferably used. Specifically, N, N'-bis-2,6-diisopropylphenylcarbodiimide, N,
N'-bis-1,3,5-triisopropylbenzene carbodiimide and the like can be mentioned.

As the hydrazine type hindered phenol, those commercially available from Ciba-Geigy under the trade name of “IRGANOX MD-1024” can be used. The amount of this compound added is required to be 0.03 to 0.50% by weight, and particularly preferably 0.05 to 0.20% by weight. If the addition amount is less than 0.03% by weight, wet heat resistance performance is not exhibited, and if it exceeds 0.50% by weight, not only the effect is saturated, but also the spinnability is deteriorated, which is not preferable.

Next, the fine powder added to the core layer has a specific gravity of 4
Must be ~ 22. When a substance having a specific gravity of less than 4 is used, it is necessary to add a large amount in order to increase the specific gravity of the whole fiber, which makes it difficult to increase the strength of the obtained fiber. In addition, there are few substances with a specific gravity exceeding 22, and it is difficult to use from the economical point of view.

Further, fine powder to be added to the core layer has a specific surface area of 11m ² / g or less, it is necessary that those of preferably 1 to 10 m ² / g. When the specific surface area is larger than 10 m ² / g, the area covered with the polymer becomes large, and as a result, the fluidity of the core layer material decreases and the spinnability deteriorates. However, if the specific surface area is too small, the particle size becomes large and the fluidity of the core layer material decreases, so a specific surface area of 1 m ² / g or more is preferred.

Further, it is necessary that the fine powder has an average particle size of 1 μm or less and a maximum particle size of 2 μm or less. When the particle size is large, it is difficult to uniformly disperse the polyester in the polyester, and the spinnability is deteriorated, so that high-strength fiber cannot be obtained. In addition, it is desirable that the fine powder has a particle shape close to a sphere.

Specific examples of the fine powder include iron, lead, copper,
Silver, nickel, zinc, tin, tungsten, gold, platinum,
Examples thereof include fine powders of various metals such as stainless steel and fine powders of metal compounds such as lead oxide, barium sulfate, barium oxide, zirconium oxide, and tungsten carbide, and these may be used in combination of two or more kinds.

Appropriately selecting the kind and addition amount of the fine powder,
It is necessary to make the specific gravity of the core layer material 1.8 or more. When the specific gravity of the core layer material is less than 1.8, the ratio of the core layer to the sheath layer must be increased in order to increase the specific gravity of the whole fiber, and the ratio of the sheath layer responsible for the strength of the fiber decreases. However, it becomes difficult to increase the strength of the fiber.

The ratio of the core layer to the sheath layer is 20/80 by weight.
Appropriately 80/20, preferably 40/60 to 60/40. If the proportion of the core layer is too small, the specific gravity of the core layer material must be extremely increased, the fluidity of the core layer material deteriorates, and it becomes difficult to obtain high-strength fibers. On the other hand, if the proportion of the core layer is too large, the proportion of the sheath layer that bears the strength becomes small, and it becomes impossible to obtain high strength fibers.

Properly combining the core layer material and the sheath layer material, and spinning under the condition that high-strength fiber is obtained, and linear strength 4.
It is necessary to make the fiber 2 g / d or more, linear cutting elongation 15% or more, knot strength 3.0 g / d or more, and specific gravity 1.7 or more. By retaining such characteristics, high-speed netting can be achieved, and the fishing net has the necessary strength as a fishing net, has a high sedimentation rate in water, and has excellent shape retention against tides. Become fibers.

In the core layer and the sheath layer, various additives such as pigment,
A heat-resistant agent or the like can be included.

Next, the method for producing the fiber of the present invention will be described. First, evenly disperse the fine powder in polyester,
A core layer material with a specific gravity of 1.8 or more is obtained. As a method of adding the fine powder to the polyester, there is a method of adding to the raw material chips during melt spinning or a method of adding to the molten polymer during melt spinning, but the polyester and the fine powder are mixed in advance and melt-kneaded into chips. The workability is good,
The fine powder can be uniformly dispersed in the polyester.

On the other hand, a monocarbodiimide compound is added to the polyester for the sheath layer to prepare a sheath layer material. However, since the monocarbodiimide compound undergoes thermal denaturation when kept in a heated state, the denaturation due to heat is reduced as much as possible. In order to bring out the original properties of the carbodiimide compound, the monocarbodiimide compound is added to the polyester for the sheath layer to form the sheath layer material, and the composite melt spinning is performed together with the core layer material. In this case, the polyester chips for the sheath layer and the monocarbodiimide compound may be mixed and supplied to the extruder, but the monocarbodiimide compound may be added to the molten polyester in the middle of the extruder.

When the aromatic polycarbodiimide compound is added, the addition method may be the same as the addition method of the monocarbodiimide compound.

The composite fiber can be produced by a conventional method such as composite melt spinning and drawing. For example, first, the core layer material and the sheath layer material are each heated to a temperature of 200 to 350.
It is introduced into the spinneret pack as a melt at .degree. C., preferably 230-310.degree. C., to spin the concentric composite yarn. If the spinning temperature is too low, it is difficult to completely melt it, and if it is too high, thermal decomposition of the polymer and thermal modification of the monocarbodiimide compound occur, which is not preferable. The spun yarn is 0
It is cooled by liquid bath or gas blowing at -100 ° C, preferably 10-90 ° C. If the cooling temperature is too low, it is difficult to control the temperature and the workability deteriorates. If the cooling temperature is too high, the solidification of the cooling becomes incomplete, which is not preferable.

The yarn which has been solidified by cooling is stretched after or once it has been wound up. Stretching can be performed in a single stage or in multiple stages of two or more stages, but a two-stage stretching method is usually employed. That is, the stretching point does not move 65
Using a liquid bath at a temperature of up to 95 ° C, an oven at 100 to 200 ° C, or a heating roller at 70 to 110 ° C, a first stage drawing is performed at a magnification of 3 to 6 times, and then 100 to a temperature higher than the first stage drawing. 27
It is preferable to use a liquid bath at 0 ° C., an oven, or a heating roller to perform second stage stretching so that the total stretching ratio is 5 to 7 times. At this time, the total draw ratio is set to be higher than the first-stage draw ratio. If the drawing temperature is too low, the heating of the fiber will be insufficient, which will cause movement of the drawing point, yarn breakage, and yarn unevenness.If the drawing temperature is too high, superdraw phenomenon and fiber melting will occur, and the molecules will be oriented for drawing. Becomes difficult. Further, if the total draw ratio is less than 5 times, the yarn quality of the obtained fiber, particularly the linear strength, becomes low, and if it exceeds 7 times, voids are generated in the fiber and satisfactory yarn quality performance is not only exhibited. There is also no knot strength.

The liquid bath is usually used in the case of a monofilament, and in the case of a multifilament, it is cooled and stretched in a gas. Stretched yarn is 200-50
It is preferable to perform relaxation heat treatment with a relaxation rate of 3 to 15% using an oven at 0 ° C or a heating roller at 150 to 250 ° C. If the temperature of the relaxation heat treatment is too low, the heat treatment effect on the fiber will be insufficient, and if the temperature of the relaxation heat treatment is too high, the thermal decomposition and deterioration of the polymer will occur on the fiber surface, and a fiber satisfying the target yarn quality performance can be obtained. Absent. Further, if the relaxation rate is less than 3%, the fiber has a high heat shrinkage rate and becomes unsuitable for practical use, and if it exceeds 15%, yarn sagging occurs in the relaxation heat treatment stage, resulting in poor operability and the target yarn. It does not show quality performance.

In the case of monofilament, the fineness of the yarn is
In the case of 50 to 1500 denier and multifilament, it is suitable to set the single yarn fineness to 8 to 50 denier and the total fineness to 200 to 2000 denier.

A fishing net can be obtained by net-making the core-sheath composite fibers as described above by a conventional method. The structure of the fishing net may be a generally known structure, and the fishing net of the present invention can be suitably used as a stationary net or a net.

[0042]

In the present invention, a polyester composition having a high specific gravity containing fine powder is used as a core layer material, and a polyester having a low carboxyl group end-capped with a monocarbodiimide compound is used as a sheath layer material. It is possible to obtain a polyester fiber for marine products which has excellent properties and resistance to amine decomposition, has high specific gravity, high strength, and is excellent in dimensional stability.

When an aromatic polycarbodiimide compound is used in combination, it reacts with a carboxyl terminal group during melt spinning to block the terminal and at the same time bring about a thickening effect and improve the spinnability.

Further, an end-capping reaction is performed by adding an excess amount of a carbodiimide compound as an end-capping agent to the amount of carboxyl end groups of the polyester, and at the same time, an unreacted carbodiimide compound is left in the fiber to form in the decomposition process. By optionally blocking the carboxyl terminal group, resistance to decomposition and deterioration is developed.

A fishing net using such a high specific gravity and high strength composite fiber has excellent settling property in water and shape retention property, and at the same time has resistance to hydrolysis and amine decomposition.
Has excellent durability.

[0046]

Next, the present invention will be described specifically with reference to examples. The hydrolysis resistance was evaluated by the tenacity retention after treatment in saturated steam at 120 ° C for 10 days, and the amine decomposition resistance was evaluated by the tenacity retention after treatment at 135 ° C for 5 hours in ammonia gas.

Example 1 35% by weight of polyethylene terephthalate having a relative viscosity of 1.56 and a carboxyl end group amount of 17.5 eq / t, an average particle size of 0.63 μm, a maximum particle size of 1.30 μm, a specific surface area of 2.9 m ² / g and a specific gravity of tungsten of 19.3. 65% by weight of powder is melted and kneaded into chips,
A chip for core layer material having a specific gravity of 3.4 was obtained. This chip for core layer material is supplied to an extruder and melted at 270 ° C, while a polyethylene terephthalate chip with a relative viscosity of 1.56 and a carboxyl end group amount of 17.5 eq / t is added to bis (2,6-diisopropylphenyl) carbodiimide (monoester). (Carbodiimide) 1.0 wt% and hydrazine-based hindered phenol (stabilizer) 0.1 wt% are added and supplied to another extruder, and melted at 295 ° C to form a sheath layer material and composite with the above core layer material. Spun At this time, the molten polymer was filtered, rectified and formed into a core-sheath structure composite flow in a spinneret pack at a temperature of 295 ° C, discharged from a spinning hole with a diameter of 1.3 mm, and the core-sheath composite weight ratio was 40/60. It was a composite monofilament. After cooling the spun yarn in a water bath at 65 ° C, 1
It was passed through a heating medium bath at 00 ° C and stretched 4.9 times, then 2
It was drawn through an oven heater at 00 ° C to 1.16 times (total draw ratio: 5.7 times), and further passed through an oven heater at 220 ° C to be subjected to a relaxation heat treatment with a relaxation rate of 12% to obtain a core-sheath composite monofilament. .

Example 2 In Example 1, N, N'-bis-2,6 was further added to the sheath layer.
A core-sheath composite monofilament was obtained in the same manner as in Example 1 except that 0.2% by weight of diisopropylphenylcarbodiimide (polycarbodiimide) was added.

Example 3 The same core layer material and sheath layer material as in Example 1 were used, and the diameter was
It was discharged from a spinneret having 20 0.6 mm spinning holes to obtain a concentric circular composite multifilament having a core-sheath composite weight ratio of 40/60. After blowing 20 ° C air on the spun yarn to cool it,
Draw 5.00 times using 90 ° C heated roller, then 2
Stretched to 1.27 times using a 40 ° C heating roller (total stretching ratio 6.
35 times) and further subjected to relaxation heat treatment at a relaxation rate of 6% using a heating roller at 170 ° C. to obtain a core-sheath composite multifilament.

Example 4 A core-sheath composite monofilament was obtained in the same manner as in Example 1 except that polyethylene terephthalate having a relative viscosity of 1.57 and a carboxyl terminal group amount of 14.4 eq / t was used as the polyester for the sheath layer.

Example 5 A core-sheath composite monofilament was obtained in the same manner as in Example 1 except that polyethylene terephthalate having a relative viscosity of 1.45 and a carboxyl terminal group amount of 19.6 eq / t was used as the polyester for the core layer.

Example 6 A core-sheath composite monofilament was obtained in the same manner as in Example 1 except that the composite weight ratio of the core-sheath was 50/50.

Examples 7 to 9 Core-sheath composite monofilaments were obtained in the same manner as in Example 1 except that the amount of the monocarbodiimide compound shown in Table 1 was added to the core-sheath material when it was melted in the extruder.

Example 10 A core layer material having a specific gravity of 2.6 was obtained instead of the core layer material in Example 1 with the proportion of the fine tungsten powder being 50% by weight, and the core / sheath composite weight ratio was 50/50. A core-sheath composite monofilament was obtained in the same manner as in Example 1.

Example 11 A core layer material having a specific gravity of 4.5 was obtained instead of the core layer material in Example 1 with a proportion of tungsten fine powder of 75% by weight, and the core-sheath composite weight ratio was 30/70, except that A core-sheath composite monofilament was obtained in the same manner as in Example 1.

The results of Examples 1 to 11 above are summarized in Table 1.
Shown in

[0057]

[Table 1]

Comparative Examples 1 to 4 Table 1 shows the addition amount of the monocarbodiimide compound to the sheath layer material.
A core-sheath composite monofilament was obtained in the same manner as in Example 1 except that the above was changed. However, in Comparative Examples 2 and 4,
The spinnability was poor.

Comparative Example 5 A core-sheath composite monofilament was obtained in the same manner as in Example 1 except that polyethylene terephthalate having a relative viscosity of 1.42 and a carboxyl terminal group amount of 27.3 eq / t was used as the polyester for the sheath layer.

Comparative Example 6 A core-sheath composite was prepared in the same manner as in Example 1 except that the core layer material in Example 1 was replaced with a core layer material having a specific gravity of 1.8, which was obtained with a proportion of fine tungsten powder of 25% by weight. A monofilament was obtained.

Comparative Example 7 As fine powder, average particle size 1.30 μm, maximum particle size 2.41 μm,
When an experiment was performed in the same manner as in Example 1 using iron fine powder having a specific surface area of 15.3 m ² / g and a specific gravity of 7.9, it was difficult to make the core layer material into chips, and the spinnability was also poor.

The results of Comparative Examples 1 to 6 are summarized in Table 2.
Shown in

[0063]

[Table 2]

Example 12 Five monofilaments obtained in Example 1 were combined 21
Using 30 yarns of 00d, net it with a Russell knitting machine,
After treatment in hot water at ℃, it was dried and heat treated at 170 ℃. The net-making property was good, the obtained net had a fast sedimentation speed in seawater, little net swaying due to waves, was suitable as a fishing net, and was excellent in durability.

[0065]

Industrial Applicability According to the present invention, there is provided a polyester fiber for marine products which is excellent in hydrolysis resistance and amine decomposition resistance, has high specific gravity and high strength. A fishing net using this fiber has excellent sedimentation properties, less shaking in the water, excellent fishing operability, and excellent durability.

Claims (5)

[Claims] 1. A polyester having a specific gravity of 4 to 22 as a core layer,
Specific surface area 11 m ² / g or less, average particle size 1 μm or less, maximum particle size 2
A mixture having a specific gravity of 1.8 or more mixed with fine powder of a metal and / or a metal compound of μm or less, a polyethylene terephthalate having a carboxyl end group content of 20 eq / t or less as a sheath layer, or a polyester mainly composed of this monocarbodiimide compound 0.3 to 2.0 % By weight and N, N'-bis [3- (3,5
-Di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine A core-sheath composite fiber obtained by melt spinning using a mixture containing 0.03 to 0.50% by weight of the mixture and stretching, wherein the carboxyl terminal of the sheath layer is Base amount 5eq / t or less, linear strength 4.2g / d or more, linear cutting elongation 15% or more, knot strength 3.0g / d
As mentioned above, the polyester fiber for marine products has a specific gravity of 1.7 or more. 2. The polyester fiber for marine products according to claim 1, wherein 0.02 to 1.00% by weight of an aromatic polycarbodiimide compound is added to the sheath layer. 3. The method for producing a polyester fiber for marine products according to claim 1, wherein the following steps are sequentially performed. (a) Polyester with a specific gravity of 4 to 22, a specific surface area of 11 m ² / g or less,
Metals with an average particle size of 1 μm or less and a maximum particle size of 2 μm or less and /
Or evenly disperse a fine powder of a metal compound to obtain a specific gravity of 1.8.
The step of obtaining the above core layer material, (b) a monocarbodiimide compound on the polyethylene terephthalate having a carboxyl end group content of 20 eq / t or less or a polyester mainly composed of this
0.3 to 2.0% by weight and N, N'-bis [3- (3,5-di-
t-butyl-4-hydroxyphenyl) propionyl]
By adding 0.03 to 0.50% by weight of hydrazine to form a sheath layer material and performing composite melt spinning with the core layer material, the sheath layer has a carboxyl end group content of 5 eq / t or less and a fiber specific gravity of 1.7.
The step of obtaining the core-sheath composite unstretched fiber as described above, (c) the core-sheath composite unstretched fiber is stretched, the linear strength is 4.2 g / d or more, and the linear cutting elongation is
A process to obtain composite fibers with a knot strength of at least 15%, a knot strength of at least 3.0 g / d, and a specific gravity of at least 1.7. 4. The method for producing a polyester fiber for marine products according to claim 3, wherein 0.02 to 1.00% by weight of an aromatic polycarbodiimide compound is added when the sheath layer material is formed in the step (b). 5. A fishing net braided with the polyester fiber for marine products according to claim 1.