JPH10273828A - Abrasion resistant sheath core type high specific gravity conjugate fiber and fishing net composed of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a conjugate fiber having characteristics such as a high specific gravity and a high strength, good in abrasion resistance, and easily produced industrially, and a fishing net having a good abrasion resistance and a high specific gravity. SOLUTION: This abrasion resistant sheath core type high specific gravity conjugate fiber has >=15 wt.% and <=30 wt.% content of high density inorganic particles based on the total of the conjugate fiber in a core component, >=0.7 and <=0.85 intrinsic viscosity of the total conjugate fiber, <=30 equivalent/1 amount of carboxyl terminal group, <=30 vol.% ratio of the core component, also >=1.50 specific gravity and >=4.0 g/d strength in an essentially concentric circle-shaped sheath core type conjugate fiber in which a high specific gravity inorganic particles are blended mainly in the core component and both sheath and core components consist of a polyester. Further, a fishing net is produced by using a net yarn of twisted yarns having a double yarn structure or a double double yarn structure of interlaced filament yarns consisting of the above fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core-sheath type high specific gravity conjugate fiber having a core portion made of a thermoplastic polymer containing a high specific gravity inorganic substance, the fiber having high specific gravity and abrasion resistance. It is about.

[0002]

2. Description of the Related Art There has been a demand for the appearance of high specific gravity fibers as general industrial fibers such as fishing nets, ropes, and wave breaking nets, and as interior decoration fibers such as curtains and curtains.

[0003] In some fishing nets, nylon sheaths are used.
Composite fibers having lead metal as a core have been put to practical use. However, in the case of a composite fiber having a sheath made of nylon and a core made of lead metal, the core (lead metal part) is not sufficiently stretched at the time of stretching, so that an intermittent state occurs in which the core is cut. There is a problem that the fiber diameter in the fiber longitudinal direction fluctuates greatly, the fibers become thick and non-uniform, and the twisting property at the time of net-making decreases.

Japanese Patent Laid-Open Publication No. Sho 62-15327 discloses a composite fiber having a core made of a thermoplastic polymer containing a fine lead alloy in order to solve the above-mentioned problem.

However, in each case, the strength of the obtained composite fibers is extremely low, and it has been difficult to put these composite fibers to practical use alone. Further, in the case of a fiber using lead metal or a lead alloy, lead damage occurs at the time of incineration or after disposal, so that it cannot be easily used from the viewpoint of global environmental pollution.

From these viewpoints, Japanese Patent Application Laid-Open No. 8-31172
In the publication No. 1 and the like, iron oxide,
Core-in-sheath type composite fibers containing a high specific gravity substance not containing lead such as titanium oxide and barium sulfate have been proposed.

However, these prior arts have not studied the prevention of fibrillation and abrasion resistance of polyethylene terephthalate used as a sheath component, and have a carboxyl terminal group of 35 to 40 equivalents / t, similar to a conventional polyester fiber for fishing nets. However, there is a problem that the wear resistance during use is unsatisfactory because polyethylene terephthalate is used.

[0008] Therefore, due to these causes, fishing nets, ropes, and wave-breaking nets are likely to be scraped under high tension when in contact with the hull, quay, seabed, etc. at the time of expansion or recovery, and A curtain has a short product life due to abrasion due to shaking during opening and closing and during use.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems in the prior art, to provide extremely excellent abrasion resistance, high specific gravity and high strength, and to be used in general fishing nets and the like. An object of the present invention is to provide a conjugate fiber useful as a high specific gravity fiber for industrial use, interior decoration, and the like.

[0010]

The above object can be achieved by the following means. High specific gravity inorganic particles are mainly blended in the core component, and the content of the high specific gravity inorganic particles in the whole composite fiber is 15% by weight in the substantially concentric core-sheath type composite fiber in which both the core component and the sheath component are made of polyester. Above 3
0 wt% or less, and the intrinsic viscosity of the entire composite fiber is 0.7
0.85 or less, the carboxyl terminal group amount is 30 equivalents / t or less, the ratio of the core component is 30% by volume or less, the specific gravity is 1.50 or more, and the strength is 4.0 g / d or more. Wear-resistant core-sheath type high specific gravity composite fiber.

[0011]

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

The core-sheath type high specific gravity composite fiber of the present invention is obtained by blending high specific gravity inorganic particles mainly into a core component. By making the core-sheath type composite fiber, it is possible to obtain a fiber having a high specific gravity without having a large amount of particles in the fiber surface layer, thereby preventing abrasion of a high-order processing device such as twisting, weaving, and knitting, and High specific gravity fibers having good permeability in these steps can be obtained.

Both the core component and the sheath component of the composite fiber of the present invention are polyester. By using polyester, fibers having high specific gravity and high strength can be obtained. The polyester in the present invention is a polyester having ethylene terephthalate, trimethylene terephthalate, tetramethylene terephthalate or ethylene naphthalate as a main repeating unit.

As the sheath component polyester of the present invention, among these polyesters, polyethylene terephthalate, which is easily obtained with high wear resistance and high strength, is preferable. The copolymer component may contain 15 mol% or less of dicarboxylic acid or diol, but for high strength, the copolymerization ratio is preferably 5 mol% or less.

If the sheath component is made of polyethylene terephthalate and the core component is made of polytetramethylene terephthalate or an ethylene terephthalate-based polyester having a copolymerization ratio of 7 mol% to 40 mol%, the melting point of the core component is reduced. Since the final heat treatment temperature can be increased to about the melting point of the core component by melt-spinning due to a large amount of high specific gravity inorganic particles, voids inside the fiber generated at the time of drawing can be reduced by lowering the final heat treatment temperature by at least 10 ° C. From the viewpoint of increasing the specific gravity.

The form of the core-in-sheath type composite of the present invention is a substantially concentric core-in-sheath type composite, whereby the wear resistance and strength can be improved by maximizing the thickness of the sheath component. it can. Multiple concentric composites such as triple and quadruple may be used, but simple double concentric composites are preferable from the viewpoint of wear resistance.

The cross-sectional shape of the fiber of the present invention may be any known cross-sectional shape such as a circle, a flat, and a polygon. Among them, a round cross section and a polygonal shape having four or more squares are preferable because the thickness of the sheath component can be utilized to the maximum.

It is necessary that the content of the high specific gravity inorganic particles with respect to the entire conjugate fiber of the present invention is not less than 15% by weight and not more than 30% by weight. If the content of the particles is less than 15% by weight, it is difficult to obtain a high specific gravity of 1.50 or more, which is the target of the present invention. On the other hand, if the content of the particles exceeds 30% by weight, it is difficult to obtain the high strength targeted by the present invention. A preferable range of the content is 17% by weight or more and 28% by weight or less, and a more preferable range is 19% by weight or more and 25% by weight or less.

Here, the high specific gravity inorganic particles are inorganic particles having a specific gravity of 2 or more, which is higher than the specific gravity of the polyester as the sheath component, and preferably an inorganic particle having a specific gravity of 3 or more. From the viewpoint of incineration as a disposal method after use of the fiber, the particles are preferably a metal compound which does not substantially melt or decompose at a temperature lower than 1000 ° C. Specifically, it is a lead-free metal such as barium, titanium, aluminum,
Iron, copper, tungsten, bismuth, copper, zirconium,
Metals such as antimony, manganese and chromium and their compounds,
And mixtures thereof, and aluminum oxide, zinc oxide, tungsten, ferric oxide, titanium dioxide, lithopone, and barium sulfate are preferably used. Among these, barium sulfate, which can be easily incorporated into the polyester at a high concentration, is particularly preferable.

The intrinsic viscosity of the conjugate fiber of the present invention is from 0.7 to 0.85. If it is less than 0.7, the abrasion resistance is inferior. If it exceeds 0.85, it is difficult to mix high specific gravity particles at a high concentration, or it may be caused by the particles during melt spinning and stretching. As a result, the amount of voids generated increases, and it is difficult to obtain fibers having a high specific gravity. From this perspective,
It is preferable that the intrinsic viscosity is 0.80 or less. Also,
In order to reduce the void amount, the intrinsic viscosity of the polyester as the core component is preferably lower than the intrinsic viscosity of the sheath component by 0.10 or more, more preferably 0.20 or more.

Further, the amount of carboxyl terminal groups of the conjugate fiber of the present invention must be 30 equivalents / t or less.
If it exceeds 30 equivalents / t, the abrasion resistance becomes poor. When the content is 25 equivalents / t or less, the wear resistance is further improved. From the viewpoint of the polymerization cost of the polyester, the amount of the carboxyl terminal group is preferably 10 equivalents / t or more. It is not clear why reducing the amount of carboxyl end groups is effective in improving abrasion resistance,
It is considered that local and instantaneous frictional heat generated upon contact and rubbing deteriorates the polyester substrate. Further, in marine material applications such as fishing nets, it is effective to reduce the amount of carboxyl terminal groups to the range of the present invention even for amine deterioration due to biological adhesion.

The ratio of the core component of the composite fiber of the present invention is 30% by volume or less. When the content exceeds 30% by volume, the thickness of the sheath component decreases, and the wear of the core component having poor wear resistance proceeds quickly, and the wear resistance of the entire composite fiber decreases. From this viewpoint, the content is preferably 25% by volume or less, more preferably 20% by volume or less. Conversely, if the ratio of the core component is too low, it becomes difficult to increase the specific gravity, so that it is preferably at least 10% by volume.

Next, it is necessary to satisfy a specific gravity of 1.50 or more. When the specific gravity is less than 1.50, when the fishing net and the rope are thrown into the sea, the so-called drifting phenomenon of the movement of the fishing net and the rope occurs due to the movement of the seawater, and the durability of the fishing net and the rope is reduced, and the catch is also reduced. In addition, when used for interior decoration such as curtains, beautiful silhouettes cannot be obtained by eliminating wrinkles generated at the time of opening and closing. In this respect, the specific gravity of the core-sheath conjugate fiber of the present invention is preferably 1.55 or more, more preferably 1.60 or more.

The core-sheath type composite fiber of the present invention has a strength of 4.0 g.
/ D or more. 4.0 g / d strength
If less than a single fiber is tailored into a fishing net, rope, or the like, the net tends to break or break. Also, when used for interior decoration such as curtains, tears are likely to occur. From this viewpoint, the strength of the core-sheath type conjugate fiber of the present invention is 4.5 g /
It is preferably at least d.

In the core-sheath type composite fiber of the present invention, the area of the cavity and the crack existing inside the fiber is 5 times the cross-sectional area of the fiber.
% Is preferable. When a fiber containing a large amount of particles in a thermoplastic polymer is drawn at a high draw ratio, cracks are generated between the particles and the thermoplastic polymer, and the cracks are particularly large portions where the particles are aggregated. It is easy to reduce the fiber specific gravity.

In order to reduce cavities and cracks generated inside the fiber, a method of improving the wettability between the particles and the thermoplastic polymer used as the core component by surface modification of the particles, stretching at the time of spinning, and the like. Reduction of magnification, adoption of high-temperature conditions during stretching, adoption of high-temperature and relax conditions in final heat treatment, and the like can be mentioned. At this time, the stretching ratio was 5.5.
The final heat treatment temperature is not higher than the melting point of the polyester of the sheath component, particularly 1 point lower than the melting point.
The temperature is preferably 5 ° C. or lower, and these conditions are preferably employed from the viewpoint of increasing the specific gravity.

The composite fiber of the present invention is used as a multifilament, a monofilament or a staple fiber. For multifilament,
Depending on the application, the fineness of the single yarn is suitably 2 d or more and 40 d or less, and is preferably 10 d or more from the viewpoint of abrasion resistance. When the thickness is 10 d or more, the thickness of the sheath component is increased, and the wear resistance is improved. In particular, for fishing nets, by setting it to 15d or more, the abrasion resistance is extremely improved. Also, the total fineness of the multifilament is suitably from 50d to 3000d. When a monofilament is used, 20d to 100000d is used depending on the application.
The degree is adopted. In the case of a staple fiber, a single fiber fineness of about 1d to 40d is employed.

In the case of a multifilament yarn, it is preferable that entanglement having a degree of entanglement of 8 or more is provided. By giving high convergence of 8 or more entanglement, twisting, weaving,
It is possible to prevent the single yarn from being broken during knitting, and the wear resistance is improved. In addition, the passability of these steps is also improved.

The thermoplastic polymer of the core component and the sheath component of the conjugate fiber of the present invention may be added with a weathering agent, an antioxidant, a pigment such as carbon black, etc., if necessary, as long as the inherent properties are not impaired. It may contain up to 10% by weight. Especially,
In order to prevent abrasion of high-order processing equipment such as twisting, weaving, and knitting, and to obtain a high-strength, high-specific-gravity fiber having good high-order permeability, the sheath component has a content of inorganic particles of 5%. It is preferably at most 1.5% by weight, more preferably at most 1.5% by weight.

An example of the method for producing the above-described composite fiber of the present invention will be described below.

In order to reduce the amount of carboxyl end groups in the polyester used in the present invention, for example, the amount of a catalyst at the time of polymerization may be adjusted to an appropriate range. For example, when antimony trioxide is used as a polymerization catalyst, 0.03
The addition amount is preferably 5% by weight or less, more preferably 0.030% by weight or less.
The amount of carboxyl end groups can also be set within the range of the present invention by setting the initial polymerization temperature to a lower temperature of 240 ° C. or lower, or by adding a known terminal blocking agent.

In order to control the intrinsic viscosity of the polyester, generally, the polymerization time may be increased, solid phase polymerization may be employed, or the temperature set during melt spinning may be decreased. In order to achieve both abrasion resistance and high specific gravity at the same time, it is necessary to set the intrinsic viscosity of the base polyester of the core component, which is blended with a large amount of high specific gravity inorganic particles, low and the intrinsic viscosity of the sheath component polyester high. Is preferred. In this case, the difference between the intrinsic viscosity of the core component and the intrinsic viscosity of the sheath component is preferably 0.10 or more by a known intrinsic viscosity control method, and is preferably 0.20 or more.
The above is more preferable. In order to obtain the conjugate fiber having the intrinsic viscosity range of the present invention, the intrinsic viscosity of the polyester used for the sheath component is preferably 0.80 or more, and 0.90 or more.
The above is more preferable.

It is necessary to uniformly mix high specific gravity inorganic particles in the polyester of the core component. For this purpose, a method is adopted in which the base polyester and the inorganic particles are each measured, melt-kneaded, and then extruded from a nozzle and cut into pellets, or are supplied to the composite spinning machine immediately after melt-kneading. Is done. At the time of kneading, a pigment, an antioxidant, a dispersant, a plasticizer, a weathering agent and the like can be added directly or as a master batch, if necessary. The polyester containing the inorganic particles cut into pellets may be used as it is for spinning, or may be used after the degree of polymerization is increased again by solid-phase polymerization if necessary. In addition, it is preferable to stir the pellets by a stirrer or the like until the pellets are charged into the spinning device, so that a high specific gravity fiber having a uniform blending amount of particles can be obtained.

On the other hand, the polyester used for the sheath component may be one obtained by polymerization according to a conventional method.
When the above-mentioned additives such as pigments are blended, it is preferable to blend them directly or as a master batch as in the above.

The above-mentioned polyester pellets of the core and sheath components are melted by separate extruders, respectively, weighed, guided to a composite spinning pack, and formed into a concentric core-sheath composite flow in a core-sheath composite spinneret. Discharge. The discharged core-in-sheath type composite fiber is delayed-cooled through a heating atmosphere region provided directly below the spinneret, introduced into the cooling region, blows cooling air, and passes through a spinning cylinder to form a yarn.

The temperature in the heating atmosphere is 120 to 350.
° C and its length may be 5 to 300 cm. In the cooling region, normal temperature air or a gas having a temperature of less than 120 ° C may be blown at a speed of 15 to 50 m / min. The conditions of the heating zone and the cooling zone are determined by appropriately setting the cooling orientation pattern of the spun yarn in consideration of the setting conditions such as the molecular weight of the polymer of the spun yarn, the fineness of a single yarn, the draft rate, and the number of single yarns. Is selected as appropriate.

The fibers which have passed through the cooling zone and have been cooled and solidified are:
Spinning oil is applied, 500m / min or more, 2000m /
It is wound on a roll having a speed of not more than one minute, and is stretched continuously or after being wound once. By setting the spinning speed to 500 m / min or more, productivity is improved, and 2000 m / min.
It is preferably employed because the spinning property is improved by setting the content to not more than minutes.

The stretching is preferably performed at a draw ratio of 3.0 times or more and 6.5 times or less, since it is possible to achieve high strength and to reduce cavities and cracks generated inside the fiber.

Further, it is preferable to carry out multi-stage drawing of two or more stages, since both the spinning property and the high strength can be achieved at the same time. From this viewpoint, when performing two or more stages of stretching, the first stage stretching distribution is preferably in the range of 50 to 80% of the total stretching distribution.

The temperature of the yarn to be subjected to the first stage of drawing is 100
It is preferable that the temperature is not lower than 180 ° C and not lower than 180 ° C. When the temperature of the yarn to be subjected to the first-stage drawing is lower than 100 ° C., voids inside the fiber increase, and it is difficult to obtain a high specific gravity fiber. 2
It is preferable to set the drawing and heat treatment temperature at the stage after the first step to a high temperature of 120 ° C. or higher, because it is possible to control the generation of cavities and cracks generated inside the fiber and achieve a high specific gravity. Heat treatment at a temperature lower by 15 to 40 ° C. than the melting point of the polyester as the sheath component is preferable from the viewpoint of increasing the specific gravity.

As a method for applying heat required for drawing to the yarn, a method such as roll heating, steam heating, and hot liquid heating may be used.

Further, the entanglement can be applied at any position up to the winding, but it is possible to apply the entanglement between rolls having a low tension, such as before the relaxing roller or immediately before the winding, in order to obtain a highly entangled yarn. Is preferred.

The thus obtained core-sheath type conjugate fiber of the present invention has a high specific gravity, a high strength and abrasion resistance. Therefore, it is used for fishery materials such as fishing nets such as fixed nets, fishing net ropes, tex and ship ropes. It is extremely useful for civil engineering materials such as silt fences and oil fences, general industrial applications such as ropes, interior decoration applications such as curtains and curtains, and other clothing applications. The high specific gravity composite fiber of the present invention can be particularly preferably used for fishing nets.

When the composite fiber of the present invention is used for a fishing net, it is preferably used for a fixed net, a laying net, a purse seine, a longline, and the like. Depending on the structure of the net, the knotting method of the net thread, the location of the net, and the like, there are knot nets, knotless nets, Myel nets, Russell nets, and the like, but it is preferably used for any type of fishing net. Among fishing net applications, it is particularly excellent for fixed nets such as knotless nets and Russell nets.

An example of a knotless network is shown below. When processing the core-sheath type high specific gravity composite fiber of the present invention into a knotless fishing net, a multifilament yarn composed of a plurality of the composite fibers becomes a twisted yarn having a double yarn structure composed of a bottom twist and a top twist, or It is preferable to form a net yarn as a twisted yarn having a double-twisted structure of primary twist, medium twist and upper twist. In terms of the relationship between the twist form and the abrasion, the double yarn structure is more preferably used because the original yarns constituting the net yarn are more uniform than the double yarn structure, and the twist is applied more and the abrasion is excellent.

In general, the number of twists of the net yarn affects the strength, hardness (meshness), abrasion resistance, etc. of the netting, and the higher the number of twists, the higher the hardness and abrasion resistance. Power drops. Abrasion resistance is particularly important because the mesh comes into contact with various rollers and mesh yarns during fishing, and abrasion-resistant mesh has excellent durability. Sex may be considered important.

In the core-sheath type high specific gravity composite fiber of the present invention, the polymer that contributes to the abrasion resistance is mainly composed of the sheath portion.
It is effective to improve the wear resistance by using a means such as increasing the number of twists, and the twist coefficient K is preferably 2100 or more. However, if the number of twists is too large, the strength is reduced as described above. Therefore, the twist coefficient K is preferably 3000 or less, and more preferably 2500 or less.

The twist coefficient K mentioned here is represented by the following equation (1). In the case of a double yarn structure composed of a ply twist and a ply twist, the ply twist, the ply twist, the ply twist, and the In the case of a twisted double yarn structure, it refers to the twist coefficient at the time of medium twisting. Specifically, the following method is used. K = T · (Dn) ^1/2 (1) (however, T: twist number / 10 cm, Dn: ply yarn fineness)

A. In the case of a double yarn structure: (1) Attach a net yarn to the twister so that the test length is 30 cm. (2) Untwist the twist and determine the number of twists. (3) Cut off the other thread, leaving one of the lower strands. (4) Return only the number of twists. (Return in the opposite direction.) (5) Re-grip so that the test length becomes 30 cm. (6) Untwist the twist and determine the number of twists (T). (7) Determine the fineness (Dn) of the yarn constituting the primary twist. (Original yarn fineness x number of yarns) (8) The twist coefficient K is obtained from the equation (1).

B. In the case of double yarn structure: (1) Attach a net yarn to the twister so that the test length is 30 cm. (2) Untwist the twist and determine the number of twists. (3) Cut out the other thread, leaving one of the middle twists. (4) Return only the number of twists. (Return in the opposite direction.) (5) Re-grip so that the test length becomes 30 cm. (6) Untwist the middle twists and determine the number of twists (T). (7) Determine the fineness (Dn) of the yarn constituting the middle twist. (Original yarn fineness x number of yarns) (8) The twist coefficient K is obtained from the equation (1).

An example of the knotless knitting method will be described below. Several or more raw yarns (multifilament yarns or the like) are aligned and given a bottom twist by a twisting machine or the like, and several such twisted yarns are wound around a spindle (metal tube) in a state of being twisted. While this spindle rotates and twists in the middle, further twisting is performed while intersecting with another adjacent spindle to form a mesh yarn, and at the same time, a mesh is formed. Such a knotless knitting machine includes a round type, a vertical type and the like, and any type may be used.

[0052]

The present invention will be described below in detail with reference to examples. In addition, the physical property in an Example was measured as follows.

A. Compounding amount of high specific gravity particles (A): The sample yarn is burned in an electric furnace at 450 ° C. until it is ashed, and the compounding amount of high specific gravity particles A (%) is determined from the ratio of the initial weight of the sample yarn to the weight of the ash. Ask for.

B. Intrinsic viscosity of fiber: 8 g of sample yarn was dissolved in 100 ml of orthochlorophenol, and solution viscosity (η) was measured at 25 ° C. using an Ostwald viscometer.
The intrinsic viscosity (IV) was calculated by the following approximate formula. IV = (0.0242η + 0.2634) / (1-A /
100)

C. Carboxyl end group content of fiber 1 g of a sample yarn was dissolved in 20 ml of o-cresol, completely dissolved, cooled, added with 40 ml of chloroform, and subjected to potentiometric titration with a methanol solution of sodium hydroxide.

D. Volume ratio of core component: The fiber cross section of the sample yarn is observed by a scanning electron microscope by a standard method, and the area ratio of the core component of any 10 single yarns is measured, and the average is defined as the volume ratio.

E. Specific gravity: Measured using a specific gravity bottle.

F. Strength: Sample yarn at 20 ° C, 65% R
After being left in the temperature control room of H for 24 hours or more, using a Tensilon tensile tester manufactured by Orientec Co., Ltd., test length 25c
m, strength was calculated from the SS curve at a take-off speed of 30 cm / min by the ratio of strength to fineness.

G. Abrasion resistance test: A mesh (a net foot portion) constituting the mesh is sampled at a length of 40 cm to obtain a mesh sample.
An ABKN7V4T manufactured by Sankyo Toishi Co., Ltd. having a diameter of 150 mm was installed in an EBK grinder manufactured by Hitachi, Ltd., and one part was fixed and a 150 g load was applied to the other. The net yarn sample was worn by rotating the grinder at a rotation speed of 180 rpm in a direction in which the fixed portion of the net yarn sample was pulled. The abrasion resistance is determined by measuring the strength of the net yarn sample before the abrasion treatment and the strength of the abrasion part after 4000 rotations in accordance with the above-described strength measurement method, and determining the ratio of the strength retention (%) to the abrasion resistance. Was determined as a measure of

H. Degree of confounding (CF value): 10 for 1m sample
Apply a 0 g tension and hang vertically, insert a 6 g hook at the top so that the thread is split into two, lower the hook at a speed of about 2 cm / sec, and determine the distance until the hook stops. Was calculated by CF value = 100 cm / distance to the point of stopping (cm)

[Examples 1 and 2 and Comparative Examples 1 to 3] As a sheath component, carbon black was added at an intrinsic viscosity of 1.1% by weight and a carboxyl end group amount of 11 equivalents / t.
In addition, polyethylene terephthalate in which 0.026% by weight of antimony metal added as a catalyst was used as ammonium metal was used. As a core component, particles of precipitated barium sulfate (BaSO ₄ ) having a specific gravity of 4.3 were added to a polyethylene terephthalate having an intrinsic viscosity of 0.74 and a carboxyl terminal group amount of 21 equivalents / t in a ratio shown in Table 1, and melt-kneaded. Later, 3.0
A chip obtained by discharging from a die having a diameter of mmΦ, cooling, and cutting was used. Both the core component and the sheath component are dried by a standard method,
The mixture was melted by an extruder, guided into a composite spinning pack, and spun from a concentric core-sheath composite spinneret as a core-sheath composite fiber having a core-sheath composite ratio shown in Table 1.

At that time, the polymer of each component was melted at 290 ° C. and spun by a composite spinning pack heated to 295 ° C.

The spinneret has a hole diameter of 0.6 mmΦ and the number of holes is 60 mm.
A heating cylinder having a length of 30 cm was attached immediately below the base, and the atmosphere was heated to 310 ° C. in the cylinder. The in-cylinder atmosphere temperature is an atmosphere temperature measured at a position 10 cm below the die surface and 1 cm away from the outermost yarn.

A 70 cm long uniflow type chimney was attached under the heating tube, and the yarn was cooled at 25 ° C. by blowing 40 m / min of cold air at right angles to the yarn. Next, after applying the oil agent, the yarn speed is controlled by a take-up roll rotating at a speed of 530 m / min.
Stretched at 4 times.

The stretching is performed by five pairs of Nelson-type rolls.
It was stretched in two steps, relaxed and wound up. The temperature of the take-up roll was set to room temperature, a 3% elongation was given between the take-up roll and the supply roll heated to 120 ° C.
The first stretching is performed between the stretching rolls, the second stretching is performed between the first stretching roll and the second stretching roll heated to a temperature of 240 ° C., and the next non-heating is performed. 3% of relaxation was given by a relaxation roll of Air entanglement was applied between the relaxing roll and the winder using compressed air of 0.5 MPa.

The fineness of the obtained high specific gravity filament yarn was adjusted to 1200 denier by adjusting the amount of discharged polymer.
The single yarn fineness is 20d. Table 1 shows the evaluation results of the conjugate fibers thus obtained.

Further, two high specific gravity filament yarns (1200d) of the present invention obtained in Example 1 were bundled, and given a ply twist of 45 times / 30 cm in the S direction by a twisting machine. This bundle is wrapped around a spindle of a knotless knitting knitting machine, and the net knitting machine gives a twist of 47 times / 30 cm in the S direction while giving a medium twist of 55 times / 30 cm in the Z direction by the knitting machine, and a mesh of 91 mm in mesh size. Created the earth. The twist coefficient K of the net yarn of this net was 2,200, the net yarn strength was 74 kg, the net strength after abrasion was 55 kg, and the abrasion resistance (strength retention) was 74%.

Similarly, for Example 2 and Comparative Examples 2 and 3 having specific gravities of 1.50 or more, net yarns were prepared and the results of evaluating the abrasion resistance are shown in Table 1.

In the case of Examples 1 and 2 according to the present invention, all of high specific gravity, high strength and abrasion resistance were excellent. On the other hand, in the case of Comparative Example 1, the content of the high specific gravity particles was too small, and the particles were inferior in high specific gravity. In Comparative Example 2 in which the core component ratio was too large, and in Comparative Example 3 in which the content of the high specific gravity particles was too large, both the strength and the wear resistance were inferior.

Also, two high specific gravity filament yarns (1200d) of the present invention obtained in Example 1 were bundled and given a twist of 55 times / 30 cm in the S direction by a twisting machine. This bundle is wound around the spindle of a round knotless knitting knitting machine, and the knitting knitting machine gives a medium twist of 62 times / 30 cm in the Z direction and gives a twist of 56 times / 30 cm to give a mesh size of 91 mm.
Created a net. The twist coefficient K of the net yarn of this net is 24.
80, the strength of the mesh is 62 kg, and the strength after abrasion is 53 k
In grams, the abrasion resistance (strong retention) was 85%.

Further, the original yarn of Example 1 was twisted in a double-ply yarn structure under the condition of the above-mentioned twist factor of 2200, and a knotless stationary net was produced by a vertical knotless knitting machine. When this net was put into the sea and repeatedly tested, it was found that the fishing net caused by the flow of seawater was small and had excellent wear durability.

[0072]

[Table 1]

Comparative Example 4 The limiting viscosity of the sheath component was 0.70
A filament yarn of a conjugate fiber of Comparative Example 4 was obtained in the same manner as in Example 1, except that The intrinsic viscosity of the obtained fiber was 0.65, and the abrasion resistance was as low as 51%.

Comparative Example 5 A filament yarn of the conjugate fiber of Comparative Example 5 was obtained in the same manner as in Example 1, except that the degree of polymerization was increased by solid-phase polymerization of the particle-kneaded polyester as the core component. The intrinsic viscosity of the obtained fiber is 0.88,
The specific gravity was as low as 1.48.

Comparative Example 6 A conjugate fiber filament yarn of Comparative Example 6 was obtained in the same manner as in Example 1 except that the amount of the carboxyl terminal group of the sheath component was changed to 39 equivalents / t. The obtained fiber had a carboxyl end group content of 31 equivalents / t and a low abrasion resistance of 49%.

Example 3 A filament yarn of a conjugate fiber was obtained in the same manner as in Example 1, except that the number of holes in the core-sheath type composite die was 96. The single fiber fineness of the obtained fiber is 12.5.
d, and the abrasion resistance was as good as 66%.

Example 4 A filament yarn of a conjugate fiber was obtained in the same manner as in Example 1 except that the number of holes in the core-sheath type composite die was changed to 144. The single fiber fineness of the obtained fiber is 8.3.
d and abrasion resistance was 61%.

Example 5 A filament yarn of a conjugate fiber was obtained in the same manner as in Example 1 except that air entanglement was applied between the relaxation roll and the winder using compressed air of 0.25 MPa. . The degree of confounding is 5, and the wear resistance is 6
2%.

[0079]

The composite fiber of the present invention has high specific gravity, high strength and good wear resistance, and is extremely useful as an industrial fiber for fishing nets, ropes and the like.
It is extremely useful as a fiber for interior decoration such as curtains.

Claims (6)

[Claims] 1. In a substantially concentric core-sheath type composite fiber in which high specific gravity inorganic particles are mainly blended in a core component, and both a core component and a sheath component are made of polyester, the high specific gravity inorganic particles are contained in the entire composite fiber. If the amount is 15% by weight or more, 30
% Or less, the intrinsic viscosity of the entire conjugate fiber is 0.7 or more and 0.85 or less, and the amount of carboxyl end groups is 30 equivalents /
t or less, the ratio of the core component is 30% by volume or less,
And a wear-resistant core-sheath type high specific gravity conjugate fiber having a specific gravity of 1.50 or more and a strength of 4.0 g / d or more. 2. The wear-resistant core / sheath type high specific gravity conjugate fiber according to claim 1, wherein the single yarn fineness is 10d or more. 3. A multifilament yarn comprising a plurality of the abrasion-resistant core-sheath type high specific gravity conjugate fibers according to claim 1 or 2, wherein the multifilament yarn has an entanglement degree of 8 or more. yarn. 4. A fishing net using the abrasion-resistant core-sheath type high specific gravity conjugate fiber according to claim 1 or 2 as a net yarn. 5. A net yarn comprising a multifilament yarn comprising a plurality of the abrasion-resistant core-sheath type high specific gravity conjugate fibers according to claim 1 or 2, and having a double yarn structure having a bottom twist and a top twist. And the twisting coefficient K of the lower twist is 2100
Fishing net characterized by being at least 3,000 or less. 6. A multifilament yarn comprising a plurality of the abrasion-resistant core-sheath type high specific gravity conjugate fibers according to claim 1 or 2, wherein the multi-filament yarn has a bottom twist, a middle twist and a top twist. Twisted yarn with a structure and medium twist ratio K
Fishing net characterized by having a number of 2100 or more and 3000 or less.