JPH08296138A - High-strength composite yarn and its production - Google Patents

Abstract

PURPOSE: To produce a high-strength composite yarn, having a spun yarnlike touch feeling and excellent in color fastness to sunlight, abrasion resistance, dyeability, easy adhesion in a knitted or a woven fabric, process passableness, etc. CONSTITUTION: This high-strength composite yarn has a core component comprising an aromatic polyamide filament yarn and a sheath component comprising a crimped yarn of synthetic filaments in a core-sheath type composite yarn. The core component is cylindrically covered with the sheath component at >=80% covering degree. The composite yarn is obtained by carrying out the fluid interlacing treatment of a crimped yarn of synthetic filaments undergoing twisting-heat setting-untwisting texturing and an aromatic polyamide filament yarn.

Description

Detailed Description of the Invention

[0001]

This invention relates to high tenacity composite yarns.
More specifically, it relates to a high-strength composite yarn using an aromatic polyamide filament having a high breaking strength and an excellent covering property and a span-like texture, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, synthetic fibers such as polyester fibers have been used for clothing, materials, sports, etc. because of their excellent durability and dyeability. Has a fatal problem, and as a countermeasure against it, it has been improved by mixing with cotton, wool, etc., or by weaving or knitting. Since the introduction of aromatic polyamide fibers that far exceed the meltability and cuttability of conventional polyester fibers, hard-moving and harsh environmental conditions are required, such as mountaineering wear and baseball sliding. It has been used for special purposes such as pants, industrial gloves, military equipment, defense equipment and fire hoses.

On the other hand, an aromatic polyamide fiber used as a material for clothing is disclosed in Japanese Unexamined Patent Publication (Kokai) No. 60-34633 as a "method for producing a yarn". The aromatic polyamide fiber is drawn, stretched and drafted, and then air swirling nozzle. In Japanese Patent Application Laid-Open No. 63-92740, "Spun Yarn of Aromatic Polyamide Fiber and Manufacturing Method Thereof", staple fibers of aromatic polyamide fiber are spun and a plurality of single yarns are twisted. A spun yarn of aromatic polyamide fiber produced by the method and its production method have been proposed.

However, in each case, since long fibers are used after being made into short fibers, there is a problem that a significant improvement in yarn strength cannot be expected. In Japanese Patent Application Laid-Open No. 1-118637, "bulk processed yarn"
As such, a bulky processed yarn which is air-entangled using a "Taslan" nozzle has been proposed, but there is a problem that the yarn strength is lowered by a relaxation treatment for forming a bulky.

Usually, in order to produce a high-strength coated yarn, a covering method, a twisting method, or after twisting,
Although the method of coating with resin etc. is adopted,
All of the obtained coated yarns have no bulkiness and are not suitable for clothing because of their rigidity. Further, a core-sheath type composite yarn proposed in JP-A-3-830, in which the main component of the core component is a short fiber of aromatic polyamide fiber and the main component of the sheath component is a short fiber or a long fiber of polyester fiber The yarn structure has a problem that the yarn strength and the dyeing fastness are deteriorated because the yarn structure easily absorbs ultraviolet rays such as sunlight and becomes brittle because of insufficient coverage.

[0006]

DISCLOSURE OF THE INVENTION The object of the present invention is to have durability against strong friction, to improve deterioration of yarn strength and dyeing fastness due to ultraviolet rays such as sunlight, and to have an excellent spun-like texture. It is to provide a high-strength composite yarn and a rational manufacturing method thereof.

[0007]

The high tenacity composite yarn of the present invention has the following constitution in order to solve the above problems.

That is, in the core-sheath type composite yarn, the core component is an aromatic polyamide filament, the sheath component is a crimped yarn of synthetic fiber filament, and the sheath component is coated with the core component in a tubular shape by fluid entanglement treatment. The high tenacity composite yarn is characterized in that it has a part that is covered and has a coverage of 80% or more.

The method for producing a high tenacity composite yarn of the present invention has the following constitution.

That is, a crimped yarn of synthetic fiber filament which has been twisted, heat set and untwisted and an aromatic polyamide filament are used as supply yarns, and the crimped yarn of the synthetic fiber filament is used. A method for producing a high-strength composite yarn, which comprises performing fluid entanglement treatment while supplying at an overfeed rate higher than that of the aromatic polyamide filament by 2 to 15%.

[0011]

The high strength composite yarn of the present invention and the method for producing the same will be described in detail below.

An example structure of the high-strength composite yarn of the present invention is shown in FIG. 1 as a model, and a schematic cross-sectional structure of the yarn at each position (a), (b), (c) in FIG. 1 is shown. Models are shown in FIGS. 2, 3, and 4, respectively.

In FIG. 1, a represents an aromatic polyamide filament which is a core yarn, and b represents a crimped synthetic fiber filament which is a sheath yarn.

In the high-strength composite yarn of the present invention, (a) is covered with (b), and from the viewpoint of obtaining a span-like texture, it has a yarn form composed of a bundling portion (c) and an opening portion (d). preferable.

Further, FIG. 2 shows a state in which the core yarn and the sheath yarn are entangled in a state of being aligned in the cross section in FIG. 2A, and FIG. 3 shows the core yarn inside the sheath yarn in the cross section in FIG. 3B. The thread is tightly entwined in a twisted state, and the core thread is entwined in a tubular shape in the sheath thread opened in the cross section of FIG. 4 (c). It is the schematic which each showed the state like a model.

At positions (b) and (c), the aromatic polyamide filament of the core yarn is mostly covered with the synthetic fiber filament having the crimp of the sheath yarn, but at position (a) it is almost the same. It is not covered and is close to the aligned state.

Regarding the yarn type constituting the high-strength composite yarn of the present invention, the core yarn is an aromatic polyamide filament. This aromatic polyamide filament may be either para-type aromatic polyamide fiber or meta-type aromatic polyamide fiber, and long-fiber yarn of raw silk or the like can be used.

If the core yarn is not an aromatic polyamide filament, there is a problem that high tenacity properties cannot be obtained.

The sheath yarn is a crimped yarn of synthetic fiber filament. If the sheath yarn is not a synthetic filament,
Crimping cannot be applied, and if there is no crimp, there is a problem that the entanglement property is extremely low and the coverage of the core yarn cannot be improved.

As the synthetic fiber filament, polyester filament, polyamide filament and the like can be used. The synthetic fiber filament can be appropriately selected depending on the desired texture and coloring property.

From the viewpoint of improving the entanglement property and the covering property with respect to the core yarn, it is preferable that the sheath component has a loop, a slack, a coil, etc. In particular, the core component is cylindrically entangled and coated while having the loop. More preferably. Such a loop or the like is also effective in increasing the span-like effect.

The high tenacity composite yarn of the present invention has a coverage of 80% or more. When the coverage is 80% or less, the degree of exposure of the core yarn becomes too large, and the core yarn is apt to be embrittled by the ultraviolet rays contained in the sunlight, so that the yarn strength and the dyeing fastness are deteriorated.

The high tenacity composite yarn of the present invention is measured by using an SM color computer (model SM-3) manufactured by Suga Test Instruments Co., Ltd. to measure the high tenacity composite yarn at 5 cm.
Lightness L is set by stacking 3 sheets that are closely aligned in parallel with the square frame and fixed at both ends, and set the sample so that the light source does not pass through.
It can be calculated by measuring the value.

Generally, aromatic polyamide fibers are colored fibers such as yellow, black, and blue due to the manufacturing process of polymer synthesis. Therefore, the lightness L value before and after the composite is measured in order to know the extent of the coverage. When the lightness L value of the core yarn before compounding is L1 and the lightness L value of the compound yarn after compounding is L2, the coverage Co (%) is 100- [| L2-L1 | /
L1] × 100. For example,
When the core yarn with L1 of 60% is covered with the sheath yarn with 95% of lightness and the L2 of this composite yarn is 70%, the coverage Co
(%) Is 100- [| 70-60 | / 60] × 100
= 83.3. In addition, a core yarn with L1 of 80% has a lightness of 5
When covered with 0% sheath yarn, L2 of this composite yarn is 60%
Then, the coverage Co (%) is 100- [| 60-8
0 | / 80] × 100 = 75.0.

The brightness of 100% is based on the brightness of a white plate in which titanium oxide is baked on a ceramic plate, and the brightness of 0% is based on the condition that the measuring instrument is covered with a dark curtain so that the measuring part does not transmit and reflect light. It was done.

In the high-strength composite yarn of the present invention, since the core yarn is almost covered with the sheath yarn, it is less likely to be affected by ultraviolet rays contained in sunlight and the like, so that the reduction in yarn strength due to embrittlement is prevented and the strength retention rate is high. can do. In addition, the coating component brings about effects such as fastness to sunlight, abrasion resistance, dyeability, easy adhesiveness in knitted fabric, and process passability.

Therefore, the breaking strength of this high-strength composite yarn does not impair the level held by the core yarn and is as high as 8 to 30 g / d, and the breaking elongation can maintain the high-strength property of 5% or less.

Further, since the strength / elongation property of the aromatic polyamide multifilament yarn of the core yarn is hardly deteriorated by the entanglement treatment, it can be said that the breaking strength and the breaking elongation of the high-strength composite yarn are substantially determined by the core yarn.

In the high-strength composite yarn of the present invention, the sheath yarn has a unit length of 2 to 15% longer than that of the core yarn from the viewpoint of increasing the coverage, improving the strength and preventing the yarn streaks from being disturbed. Is preferred, and 2 to 10% longer is more preferred.

Next, the method for producing the high-strength composite yarn of the present invention will be described.

The crimped yarn to be used as the sheath yarn can be obtained by subjecting a synthetic fiber filament to a twisting-heat-setting-untwisting twisting in a twisting machine.

On the other hand, the raw yarn of the aromatic polyamide filament used as the core yarn is pulled out from the bobbin, and the crimped yarn of the synthetic fiber filament, which is the sheath yarn, is used as the supply yarn to crimp the synthetic fiber filament yarn. The high-strength composite yarn of the present invention can be produced by supplying the yarn at a higher overfeed rate than that of the aromatic polyamide filament, performing the fluid entanglement treatment, and winding the yarn on cheese.

In the method for producing the high-strength composite yarn of the present invention, the fluid entanglement treatment is used.

If a method other than the fluid entanglement treatment is used, there is a problem that the texture and yarn characteristics are adversely affected.

An example of the manufacturing process of the high tenacity composite yarn of the present invention will be described in more detail with reference to FIG.

Aromatic polyamide filaments 1 serving as core yarns and synthetic fiber filaments 2 serving as sheath yarns are unwound from bobbins. The synthetic fiber filament 2 is temporarily supplied from the feed roller 3 to the processing machine, and the twister 6
Then, it is heated by the heater 5, heat set and unraveled, and then pulled out from the delivery roller 7 to obtain a crimped yarn which is a sheath yarn.

On the other hand, the aromatic polyamide filament 1 temporarily fed from the feed roller 4 to the processing machine and the crimped yarn from the confounding roller 8 are aligned, and the crimped yarn is made more than the aromatic polyamide filament 1. It is supplied to the fluid entanglement treatment nozzle 9 under a high feed condition, and both yarns are entangled with the relaxing roller 10. The high-strength composite yarn can be obtained by winding the entangled composite yarn around the cheese with the winding roller 11.

This production method is a rational example in which a crimped yarn to be a sheath yarn is temporarily produced on a processing machine, and the crimped yarn and an aromatic polyamide filament which is a core yarn are entangled. However, the temporary twisting and the confounding treatment can be performed in separate steps.

In the entanglement treatment, the overfeed rate at the time of aligning the crimped yarn of the aromatic polyamide filament which becomes the core yarn and the synthetic fiber which becomes the sheath yarn is from the viewpoint of preventing reduction in breaking strength and breaking elongation. It is preferable that the core yarn is 0 to 5%.

The crimped yarn, which is the sheath yarn, has an overfeed rate of 2 to 15% (difference in feed rate value) more than the overfeed rate of the aromatic polyamide filament that is the core yarn.

If the difference between the overfeed rate value of the crimped yarn which is the sheath thread and the overfeed rate value of the aromatic polyamide filament that is the core thread is less than 2%, there is a problem that the coverage is lowered.

When the difference between the overfeed rate value of the crimped yarn which is the sheath thread and the overfeed rate value of the aromatic polyamide filament which is the core yarn exceeds 15%, there is a problem such as disorder of the thread line.

In the aromatic polyamide filament which is the core yarn, a multifilament having a large number of single fibers constituting the filament and a small fineness of the single fiber is preferable from the viewpoint of easy entanglement, and the number of single fibers is 10 or more. Is preferred. The total fineness of the aromatic polyamide filament is not particularly limited from a thin one having 5 denier to a thick one having 3,000 denier.

From the viewpoint of entanglement, the synthetic fiber filaments which are sheath yarns preferably have a large number of single fibers and a small single fiber fineness, and the number of single fibers is preferably 10 or more. The range of the total fineness of the filament is also not particularly limited.

Furthermore, by using a low-gloss type synthetic fiber filament containing fine particles of titanium oxide or magnesium oxide, it is possible to reflect the ultraviolet rays contained in sunlight and the like, and Since brittleness can be further prevented, the strength of the high-strength composite yarn is maintained.

In addition to the inclusion of such fine particles, synthetic fiber filaments of the sheath yarn, including Y-shaped, octagonal, star-shaped, sheath-core-shaped, thin-skin-shaped, etc., cross-sections and composite cross-sections, are included in sunlight and the like. It is more preferable because it has the effect of reflecting ultraviolet rays and improving the confounding performance.

The composite degree of the core yarn and the sheath yarn is preferably such that the weight ratio per unit length is 1 for the core yarn and 1 or more for the sheath yarn from the viewpoint of texture.

[0048]

EXAMPLES The high tenacity composite yarn of the present invention will be described in detail below with reference to examples and comparative examples. The evaluation method of the high tenacity composite yarn of the present invention will be described below.

[Overfeed rate] In FIG. 5, the peripheral speed V1 (m / s) of the feed roller 4, the peripheral speed V2 (m / s) of the interlacing roller 8, and the peripheral speed V0 of the relaxing roller 10 are shown.
(M / s) was measured, and the overfeed rate of the core yarn and the overfeed rate of the sheath yarn were calculated using the formulas shown below.

Overfeed rate (%) of core yarn = [(V1
-V0) / V0] x 100 sheath yarn overfeed rate (%) = [(V2-V0) / V
0] × 100 [Breaking strength, breaking elongation] Constant elongation type tensile tester INST
Using RON MODEL 1122 (manufactured by Instron Co., Ltd.), measurement was performed at a sample length of 20 cm and a pulling speed of 10 cm / min. The number of n was 10.

[Yarn length difference] Composite yarn length of 20 cm as a trial length
The core yarn and the sheath yarn are separated from the composite yarn, and the length l ₁ of the core yarn is ₁ under the load of 0.1 g / d for each yarn.
The length l ₂ of the sheath yarn was measured, and the yarn length difference was calculated by the following formula. n was set to 5.

Thread length difference (%) = [(l ₂ −l ₁ ) / l ₁ ] × 100 [Coverage] This high tenacity was obtained using an SM color computer (model SM-3) manufactured by Suga Test Instruments Co., Ltd. 5 composite threads
Three sheets, which were densely arranged in parallel in a cm square frame and fixed at both ends, were stacked, a sample was set so that the light source did not pass through, and the lightness L value before and after the composite was measured. When the lightness L value of the core yarn before compounding is L1 and the lightness L value of the compound yarn after compounding is L2, the coverage Co (%) is 100- [| L2-L1 | / L
1] × 100. n was 4.

[Strength retention] Suga Test Instruments Co., Ltd. Sunshine Super Long Life Weather Meter Model WE
A carbon burning light source irradiation test was performed for 500 hours using an L-SUN-HMO type, and it was calculated by the ratio of the intensity after irradiation to the intensity before irradiation. n was set to 10.

[Filament] In accordance with the seriprene method, the eyes are oriented from the cross-sectional direction of the yarn in the direction of the yarn length to visually judge the proportion of the yarn, and as a reference, the level at which weaving is possible is ○, and the level at which weaving is difficult is Δ. The non-weaving level was set to x. n was set to 1.

[Handle] 10 on a cassette-making machine with a circumference of 1 m
A yarn bundle of 0 turns was made and a sensory test of the texture was performed.
The level at which a spun-like texture was felt was rated as ○, the level close to raw silk was rated as △, and almost spun yarn was rated as ◎. n is 1
And

[Example 1] Polyester filaments (300 denier, 144 filaments) as synthetic fibers used for a sheath yarn were fed from a feed roller to a temporary twisting machine at an overfeed rate of + 2%, and twisted with a twister (number of temporary twists). (1850 T / m), after heat-setting at 225 ° C. with a heater for unraveling, it was pulled out from a delivery roller and a crimped yarn was produced.

On the other hand, an aromatic polyamide filament (200 denier, 134 filaments) having a strength of 25 g / d for yellow dyeing supplied from a feed roller and the above-mentioned temporary crimped yarn having a white strength of 3.7 g / d. Was fed to a nozzle for entangled fluid entanglement treatment and subjected to an entanglement treatment of 4 kg / cm ² with a relaxing roller and wound on cheese to produce a high-strength composite yarn.

The fluid entanglement treatment conditions were that the overfeed rate of the aromatic polyamide filament was + 2% and the overfeed rate of the crimped yarn was + 10% (difference in overfeed rate was 8%).

A high tenacity composite yarn having a high breaking strength and a span-like texture was obtained. The characteristics of the obtained composite yarn are shown in Table 1.

[0060]

[Table 1] [Example 2] Using the same yarn type and the same device as in Example 1, the overfeed rate of the aromatic polyamide filament was + 2%, and the overfeed rate of this false twist yarn was + 8%.
As a result, a high-strength composite yarn was produced (difference in overfeed ratio was 6%).

The characteristics of the obtained composite yarn are also shown in Table 1.

[Example 3] Using the same yarn type as in Example 1 and using the same apparatus, the overfeed rate of the aromatic polyamide filament was + 2%, and the overfeed rate of this false twisted yarn was + 13%. A yarn was produced (overfeed rate difference 11%).

The characteristics of the obtained composite yarn are also shown in Table 1.

[Example 4] Polyester filaments (150 denier, 72 filaments) were fed from a feed roller to a temporary twisting machine at an overfeed rate of + 2%, and twisted to give a temporary twist (2630 T / m of false twist), and a heater was used. After heat setting at 225 ° C and unraveling,
The crimped yarn was produced by pulling it out from the delivery roller. Aromatic polyamide filaments (100 denier, 75 filaments) supplied from a feed roller are aligned at an overfeed rate of + 2%, and the crimped yarn from the above-mentioned temporary is fed to an aligning and fluid entanglement treatment apparatus at an overfeed rate of + 10%, and is a relaxing roller. A high-strength composite yarn was manufactured by subjecting the cheese to a entanglement treatment of 4 kg / cm ² and winding it on cheese.

The characteristics of the obtained composite yarn are also shown in Table 1.

[Example 5] A high tenacity composite yarn was obtained by using the same type of yarn as in Example 1 and using the same method, with an aromatic polyamide filament overfeed rate of + 1% and a provisional crimped yarn overfeed rate of + 4%. Was manufactured.

Table 1 also shows the properties of the obtained composite yarn.

[Example 6] A high-strength composite yarn was prepared by using the same yarn type as in Example 1 and using the same method, with an overfeed rate of an aromatic polyamide filament of + 2% and an overfeed rate of a crimped yarn of + 10%. Was manufactured.

The characteristics of the obtained composite yarn are also shown in Table 1.

[Example 7] By using the same yarn type as in Example 1 and using the same method, the overfeed rate of the aromatic polyamide filament is + 5%, and the overfeed rate of the crimped yarn is + 15%. Was manufactured.

The characteristics of the obtained composite yarn are also shown in Table 1.

[Example 8] A high-strength composite yarn was prepared by using the same yarn type as in Example 1 and using the same method, with an overfeed rate of aromatic polyamide filament of + 5% and an overfeed rate of crimped yarn of + 20%. Was manufactured.

The characteristics of the obtained composite yarn are also shown in Table 1.

[Comparative Example 1] A fluid turbulence treatment nozzle was used in place of the fluid entanglement treatment nozzle, and a raw yarn of polyester filament (100 denier, 72 filaments) to be a sheath yarn was used as a core yarn at an overfeed rate of + 10%. Group-type polyamide filament yarns (100 denier, 75 filaments) are aligned at an overfeed rate of + 7% and HE
MA-JET T-311 (manufactured by Heberline Co., Ltd.) was supplied to a fluid turbulent nozzle and air treatment was performed at 5 kg / cm ² ,
It was wound on cheese at 300 m / min.

Since the fluid turbulence treatment was used, fibrillation occurred and the breaking strength decreased.

The properties of the obtained composite yarn are also shown in Table 1.

[Comparative Example 2] As an example of a cover thread which is most commonly used instead of a fluid entanglement treatment, an aromatic polyamide filament (100 denier, 75 filament) is used as a core thread of a covering machine, and polyester is used. Filament (100 denier, 72
(Filament) is fed from the feed roller to the temporary twisting machine at an overfeed rate of + 2%, and the twister calculates the
After applying 200 T / m and heat-fixing at 225 ° C with a heater to unravel, by using the twisted crimped yarn drawn from the delivery roller as a sheath yarn, single covering of 1200 times in the S direction and winding up on cheese , Produced a high tenacity composite yarn.

Since the cover ring was used, the texture was inferior.

The characteristics of the obtained composite yarn are also shown in Table 1.

[Comparative Example 3] As a polyester filament to be a sheath yarn, 100 denier polyester, 72 filament raw yarn (non-crimped yarn) was used, and the overfeed rate was +7.
%, 100 denier aromatic polyamide multi-filament yarn as core yarn, 75 filaments are aligned at an overfeed rate of + 2% and fed to a fluid entanglement treatment device and subjected to an entanglement treatment of 4 kg / cm ² with a relaxing roller. ,
A high tenacity composite yarn was produced by rolling it up on cheese.

The characteristics of the obtained composite yarn are also shown in Table 1.

Since the coverage was less than 80%, the texture of the yarn had a feeling of raw silk and was unsuitable for clothing.

[Comparative Example 4] Using the same yarn type as in Example 1 and using the same apparatus, the aromatic polyamide filament overfeed rate was + 1%, and the false twist yarn overfeed rate was + 2.5%. A composite yarn was produced.

The properties of the obtained composite yarn are also shown in Table 1.

Since the coverage was less than 80%, the texture of the yarn had a feeling of raw silk and was unsuitable for clothing.

[Comparative Example 5] A high-strength composite yarn was prepared by using the same yarn type as in Example 1 and using the same apparatus, with an aromatic polyamide filament overfeed rate of + 1% and a false twist overfeed rate of + 3%. Was manufactured.

The properties of the obtained composite yarn are also shown in Table 1.

Since the coverage was less than 80%, the texture of the yarn had a strong feeling of raw silk and was not suitable for clothing.

[Comparative Example 6] A high-strength yarn consisting of only the aromatic polyamide filament used as the core yarn in Example 1 was produced. As a result, the polyester filaments, which are sheath yarns, were not provided, and thus only those with poor texture were obtained.

The characteristics of the obtained yarn are also shown in Table 1.

[Comparative Example 7] A yarn consisting only of the polyester filament used as the sheath yarn used in the above-mentioned Example 1 was produced. As a result, only the one having inferior breaking strength was obtained because there was no aromatic polyamide filament as the core yarn.

The properties of the obtained yarn are also shown in Table 1.

[0093]

EFFECTS OF THE INVENTION According to the present invention, a high-strength composite yarn having a spun-like texture and being excellent in sunlight fastness, abrasion resistance, dyeability, easy adhesion in knitted fabrics, processability, etc. Can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic yarn external view showing a model of an example structure of a high-strength composite yarn of the present invention.

FIG. 2 is a schematic model cross-sectional view schematically showing a partial structural example of the high-strength composite yarn of the present invention.

FIG. 3 is a schematic model cross-sectional view schematically showing another partial structural example of the high-strength composite yarn of the present invention.

FIG. 4 is a schematic model cross-sectional view schematically showing still another partial structural example of the high-strength composite yarn of the present invention.

FIG. 5 is a schematic view showing an example of a manufacturing method of the present invention as a model.

[Explanation of symbols]

 1: Aromatic polyamide filament 2: Polyester filament package 3: Feed roller 4: Feed roller 5: Heater 6: Twister 7: Delivery roller 8: Entanglement processing roller 9: Entanglement processing nozzle 10: Relax roller 11: Take-up roller

Claims (7)

[Claims] 1. A core-sheath type composite yarn, wherein the core component is an aromatic polyamide filament, the sheath component is a crimped yarn of synthetic fiber filament, and the sheath component is coated with the core component in a tubular shape by a fluid entanglement treatment. A high tenacity composite yarn having a covered portion and a coverage of 80% or more. 2. The high-strength composite yarn according to claim 1, wherein the sheath component is a temporary twist crimped yarn of polyester filament. 3. The high-strength composite yarn according to claim 1, which is a synthetic fiber filament in which the sheath component has a loop and the core component is entangled and covered in a tubular shape. 4. The high tenacity composite yarn according to claim 1, 2 or 3, wherein the breaking strength of the whole yarn is 8 to 30 g / d. 5. The sheath yarn is 2 to 15 more than the core yarn in a unit length.
%, The high tenacity composite yarn according to claim 1, 2, 3, or 4. 6. A crimped yarn of synthetic fiber filament processed by twisting, heat setting and untwisting, and an aromatic polyamide filament are used as supply yarns, and the crimped yarn of the synthetic fiber filament is used. A method for producing a high-strength composite yarn, which comprises performing a fluid entanglement treatment while supplying at an overfeed rate higher than that of the aromatic polyamide filament by 2 to 15%. 7. The method for producing a high-strength composite yarn according to claim 6, wherein the synthetic fiber filament is a polyester filament.