JPH09157959A - Sheath and core type conjugate fiber and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sheath and core type conjugate fiber having improved interfacial peeling character by spinning a composite flow of mutually incompatible thermoplastic polymers through a flicker forming layer. SOLUTION: This fiber comprises A polyethylene terephtahlate as core component and B a high density polyethylene as sheath component. The mutually incompatible sheath and core composite flow is passed through a flicker forming layer made of three layered metal nets each having different mesh and then extruded from the nozzle to form a sheath and core type conjugated fiber which has mutually mixed A and B on the interface of sheath and core. The fiber is drawn, oil-supplied, crimped and cut to afford a sheath and core type conjugate fiber.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a core-sheath type composite fiber, and more particularly to a fiber having a good adhesion between a core component and a sheath component.

[0002]

2. Description of the Related Art Advances in fiberization technology have led to fiberization using various thermoplastic polymers. Fibers having various performances have been proposed from these polymers and put into practical use. However, with the advancement of required performances, fibers composed of polymers having two contradictory performances are required. It's coming. In order to realize this, many composite fibers have been developed, but when the polymers constituting the fibers are incompatible with each other, interfacial peeling in the fiber manufacturing process, fibrillation in the processing process, and generation of white powder become problems. However, the combinations of polymers in practical use have been quite limited.

Various proposals have been made to improve this. For example, JP-A-61-201015 and JP-A-1-92415 disclose a composite fiber composed of a modified carboxylic acid copolymer modified polyethylene and a polyester, and JP-A-2-191721 describes a polar monomer. Japanese Patent Application Laid-Open No. 62-69822 proposes a composite fiber composed of a polymerized polyolefin and a polyester, and a composite fiber composed of a polyester and a polyolefin blended with a modified polyethylene. However, there are problems that the fiber manufacturing process is complicated, the cost is increased, and the original performance of the polymer is impaired.

On the other hand, as a method of physically improving the above-mentioned interfacial peeling, a method of thickening the sheath portion of the core-sheath type composite fiber has been put into practical use, but it does not satisfy the originally required performance. Further, Japanese Patent Application Laid-Open No. 4-100920 proposes a composite fiber having a cross-sectional shape in which a core component is intricately mixed with a sheath component. However, in a spinneret having many holes, even if the core forming nozzle is deformed. In the molten state, mutually incompatible polymers work to reduce the surface area of the polymer. Therefore, in order to obtain an interfacial structure in which the core component and the sheath component are intricate, it is necessary to balance the viscosity of the core and sheath polymers. There are significant limitations and practical difficulties.

[0005]

An object of the present invention is to provide a core-sheath type composite fiber in which interfacial peeling between the core component and the sheath component is improved.

[0006]

SUMMARY OF THE INVENTION According to the invention, the above-mentioned object is achieved with thermoplastic polymers A and B which are incompatible with each other.
In the core-sheath type composite fiber, the polymer-A and the polymer-B are mixed at the core-sheath interface to provide a core-sheath type composite fiber.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the incompatible thermoplastic polymers A and B mean that the melt interfaces do not diffuse and mix with each other or react with each other. For example, the thermoplastic polymer A is a core. Thermoplastic polymer
When B constitutes a sheath and the thermoplastic polymer B constitutes a core, it means that the thermoplastic polymer A constitutes a sheath. Specific examples of the thermoplastic polymers A and B are shown below, but the present invention is not limited thereto and
As long as they are incompatible polymer-combination combinations, the polymer-combination combinations mentioned as the thermoplastic polymer A may be used.

A typical example of the thermoplastic polymer A according to the present invention is polyester. Such polyesters include terephthalic acid, isophthalic acid, naphthalene-2,5-dicarboxylic acid, α, β- (4-carboxyphenoxy) ethane, 4,4′-dicarboxydiphenyl, and an ethylene oxide adduct of bisphenol A, Adipic acid, azelaic acid, sebacic acid, trimellitic acid, ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,6-
Hexanediol, neopentyl glycol, pentaerythritol, cyclohexane-1,4-dimethanoe
Aromatic, aliphatic, or alicyclic dicarboxylic acids such as sodium chloride, polyethylene glycol, polytetramethylene glycol, and sodium salt of 5-sulfoisophthalic acid; diol; hydroxycarboxylic acids such as hydroxybenzoic acid A fiber-forming polyester synthesized from, and a polyester having polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycyclohexane terephthalate, etc. as a main component is preferable. Among them, polyesters in which 80 mol% or more, particularly 90 mol% or more of the constituent units are ethylene terephthalate units or butylene terephthalate units are preferable. Further, it does not matter even if the obtained polyester is a copolymer of polyfunctional components such as glycerin, pentaerythritol, trimellitic acid, trimesic acid and pyromellitic acid within a linear range. These polymers may contain an additive such as a matting agent such as titanium oxide or calcium carbonate, a coloring agent such as a dye or a pigment, a fluorescent whitening agent, an antioxidant, and a stabilizer.

The intrinsic viscosity of such polyester is
From the viewpoint of fiber forming property, it is preferably 0.45 to 1.00. The intrinsic viscosity is the intrinsic viscosity of the polyester forming the fiber after spinning. That is, it goes without saying that when the degree of polymerization is lowered due to thermal decomposition or hydrolysis during spinning, a polymer having a slightly higher degree of polymerization must be used to make it into fibers.

As the thermoplastic polymer B according to the present invention, polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 11, nylon 4, nylon 46; semi-aromatics composed of aliphatic diamine and aromatic dicarboxylic acid Group polyamides; polyolefins such as polyethylene, polypropylene and polymethylpentene; ethylene-vinyl alcohol copolymers and the like. These polymers may be copolymerized with a third component, or may contain a colorant such as a dye or a pigment, an optical brightening agent, a light resistance improver, a heat resistance stabilizer and the like. Good.

The degree of polymerization of the above-mentioned polyamide is about 22,000 or less in terms of number average molecular weight, particularly 6000 to 20,000,
Further, it is preferably 11,000 to 15,000. If the degree of polymerization is too high, the fluidity of the polymer will decrease, and a problem will occur in terms of spinnability. On the other hand, if the degree of polymerization is too low, there is a problem that the fiber-forming ability is significantly deteriorated. The above-mentioned semi-aromatic polyamide has 4 to 12 carbon atoms.
Is a polymer having an aliphatic diamine and an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, xylene dicarboxylic acid and naphthalene dicarboxylic acid as main components, and a polymer having an intrinsic viscosity of 0.7 to 1.10. The intrinsic viscosity is a value measured in concentrated sulfuric acid at a concentration of 0.2 g / dl at 30 ° C.

The above-mentioned ethylene-vinyl alcohol copolymer is a copolymer obtained by hydrolyzing the vinyl acetate unit of the ethylene-vinyl acetate copolymer by saponification to give a vinyl alcohol unit. The degree of saponification of vinyl acetate units is
More than about 80 mol% based on vinyl acetate units, especially 9
It is preferably 5 mol% or more. Also, ethylene-
The vinyl alcohol-based copolymer has a proportion of repeating units of ethylene of 30 to 70 mol%, and the balance is a saponified vinyl acetate unit, that is, a vinyl alcohol unit, or a vinyl alcohol unit and unsaponified vinyl acetate. Those comprising units or other vinyl-based monomer units are preferred. When the proportion of ethylene units in the copolymer is less than 30 mol%, a gel is formed in a molten state, and when it exceeds 70 mol%, the melting point is lowered and various physical properties such as hydrophilicity are lowered.

In the present invention, the core-sheath type composite fiber is targeted, but includes eccentric core-sheath type. As described above, the thermoplastic polymers A and B constituting the conjugate fiber are polymers which are incompatible with each other, and either of them may constitute the core portion, but the composite ratio of the core component and the sheath component is Core component: sheath component = 10: 90 to 90:10 (weight ratio), more preferably 25:75 to 75:25. In the present invention, even if the core component is increased, that is, the sheath component is decreased, there is no problem of peeling between the core component and the sheath component, and the fiber forming processability is improved.

Next, a method for producing the core-sheath type composite fiber of the present invention will be described. The present invention is greatly characterized in that the thermoplastic polymers A and B forming the core and the sheath are mixed at the interface. Generally in the production of fibers, the molten polymer is passed through a metering pump,
It is sent to the spinneret through the filtration layer and made into fibers. Also in the method for producing the conjugate fiber, each polymer constituting the conjugate fiber passes through the filtration layer and is then composited, and the composite fiber is formed from the spinneret while maintaining the composite form. In the present invention, after forming a composite flow of the thermoplastic polymers A and B, the “fluctuation forming layer” is further passed to mix the thermoplastic polymers A and B at the interface between the core component and the sheath component. However, interface peeling can be suppressed.

The "fluctuation forming layer" is a thermoplastic polymer A.
The material is not particularly limited as long as it has a function of disturbing the interface between the core component and the sheath component of the core-sheath type composite fiber by the passage of the composite flow of B and B. A non-woven fabric, a sintered body made of fine metal wires, a fine particle layer made of metal or ceramics, and the like can be used.
The wire mesh is made of a woven stainless steel wire or the like. The wire mesh is 30
It is preferable to use a mesh of up to 500 mesh, and it is possible to use not only one metal mesh but also several metal meshes having different meshes. Non-woven fabric consisting of thin metal wire is 5 to 1
A filter having a filtration efficiency of 00 microns and a good collection efficiency is used. As the metal fine particles, a stainless powder of 30 to 100 mesh under is used, and as the ceramic, 2 is used.
Sand of 0-100 mesh under and 100-100
0 micron glass beads are used. These materials can be used alone or in combination of two or more.

The composite flow of the thermoplastic polymers A and B that has passed through the "fluctuation forming layer" is discharged from the die and made into fibers.

The core-sheath type composite fiber of the present invention can be obtained by passing it through the above-mentioned "fluctuation forming layer", but other known composite melt spinning methods are applied. The nozzle diameter of the core forming portion is preferably 0.06 to 0.8 mm, and the nozzle diameter of the die is preferably 0.06 to 1.0 mm. The core forming nozzle and the mouthpiece nozzle may have a round shape or an irregular shape, and the mouthpiece nozzle may have a cylindrical shape or a divergent conical shape.

The core-sheath type composite fiber thus obtained is in a state in which the core and the polymers constituting the sheath are intricately and intricately interwoven at the core-sheath interface, and the respective polymers are mixed. It has a cross-sectional shape. The fact that the polymers constituting the core and the sheath are mixed means that the side faces of the composite fiber after the sheath component is dissolved and removed with a solvent in which only the polymer constituting the sheath is dissolved You can easily ask (see Figure 3).

The mixed state and intermixed state at the core-sheath interface of the core-sheath type composite fiber are slightly different depending on the combination of the thermoplastic polymers A and B, the viscosity of each polymer, etc. The larger the viscosity difference between the two, the more complex the interfacial structure is exhibited.

When the core-sheath interface structure becomes monotonous depending on the combination of the thermoplastic polymers A and B and a slight separation between the core component and the sheath component occurs, the above-mentioned "fluctuation forming layer".
It is possible to solve the problem of peeling between the core component and the sheath component by laminating several wire meshes having different meshes, or by using the wire mesh together with the metal fine wire nonwoven fabric or the fine particle layer.

[0021]

The effect of the core-sheath type composite fiber of the present invention will be described with reference to specific examples. For example, nylon sheath,
The core-sheath type composite fiber whose core part is made of polyester has a problem that the sheath component is peeled off in the drawing process, false twisting process, weaving and knitting process, etc. unless the sheath / core ratio (weight ratio) is conventionally set to 1 or more. However, in the present invention, even if the sheath / core ratio (weight ratio) is 0.5 or less, the problem of peeling of the sheath component does not occur, and it is practical and has the hydrophilicity of nylon and the function of polyester. It is possible to obtain fibers. Also, the sheath is polymethylpentene, the core is polyester,
Even if the sheath / core ratio (weight ratio) is 0.5 or less, the problem of peeling of the sheath component does not occur, and the composite fiber having a thin sheath of polymethylpentene, which has a low refractive index of 1.433, has very good colorability. It will be Further, the composite fiber in which the sheath portion is polyethylene and the core portion is polyester can be used not only in fiber manufacturing processes such as spinning, drawing, crimping and cutting, but also in carding, needle punching, hydroentanglement or papermaking processes. Since the core-sheath composite ratio can be arbitrarily selected without causing various problems due to the peeling of the sheath component, it is useful as a heat-bonding binder fiber.

[0022]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. In addition, each measured value in an Example is a value measured by the following method. (1) Melting point of polymer (° C.) It is indicated by the peak temperature of the main endothermic peak of crystal melting measured with a differential scanning calorimeter (TA3000 type manufactured by Mettler). (2) Intrinsic viscosity of polyester ([η] dl / g) It is a value measured by using an Uberode-type viscometer in a constant temperature bath at 30 ° C. using an equal amount solvent mixture of phenol and tetrachloroethane. . (3) Weight ratio of sheath / core of composite fiber Take an electron micrograph of the cross-sectional shape of the fiber, copy the photograph on graph paper, and convert it by the area ratio of the core and sheath cut off and the specific gravity of the constituent polymer. It was done.

(4) Strength (g / d) and elongation (%) of the composite fiber, tensile tester (Autograph 5KN, manufactured by Shimadzu Corporation)
D) was used, and it measured at 20 degreeC and 65RH%. (5) Core-sheath pull-out strength (g) The sheath at one end of the composite fiber is removed with a solvent or the like to remove the core by several cm.
After exposing, secure an exposed core with a length of about 1 cm from the exposure start point of the core and attach it so that both sides are sandwiched with adhesive tape, and the length of the core sheath sandwiched with the adhesive tape. Is 1
Cut to mm. The 1 mm core-sheath portion is fixed in the groove portion of the mount having a groove having a width of several mm. Then, the adhesive tape part attached so as to sandwich the exposed core part and the mount part to which the core-sheath part is fixed are sandwiched by fiber clamps respectively, and a tensile tester (Autograph 5KND) manufactured by Shimadzu Corporation is used. Use, pulling speed 2mm / min, 20 ° C,
The strength at the time when the core portion of the 1 mm core-sheath portion was pulled out from the sheath portion under 65 RH% was measured. The number of measurements is 20,
The maximum value, the minimum value and the average value are shown. (6) Core cutting strength (g) The sheath at both ends of the composite fiber is removed with a solvent to remove the core by several cm.
Exposing it, sandwiching the exposed core, and making the thread length 1 mm,
Shimadzu Corporation tensile tester (Autograph 5KN
D), pulling speed 2 mm / min, 20 ° C, 65R
The cutting strength of the core was measured under H%. The number of measurements is 20
The average is shown in the book. (7) Card dropout amount (g / ton) The staple was passed through a card machine, and the dropout amount dropped to the bottom was converted to 1 ton of cotton input.

Example 1 Intrinsic viscosity [η] = 0.67 dl / g as core component, melting point 25
Using polyethylene terephthalate at 5 ° C., high-density polyethylene having a melt index MI = 20 and a melting point of 132 ° C. as a sheath component, and compounding at a sheath / core composite ratio = 1/1, FIG.
100 with 0.25 mmφ using the spinning pack shown in
Composite spinning was performed from a 0-hole spinneret at 295 ° C. and 1000 m / min. As the “fluctuation forming layer”, three wire meshes of 325 mesh, 100 mesh and 20 mesh were laminated and used. Then, using a first bath at 80 ° C. and a second bath at 98 ° C., a two-stage drawing with a draw ratio of 3.02 was carried out, and after each step of applying an oil agent, crimping and cutting, 2.5 denier was applied. 5,
1 mm length, strength 3.2 g / d, elongation 53%, crimp number 18
25 tons of ke / in staple was obtained. There were no problems in the raw cotton manufacturing process, and good production was possible. This raw cotton was sampled at three locations, the early stage (No. 1), the middle stage (No. 2) and the later stage (No. 3) of the production, and each physical property was evaluated. Table 1 shows the results. As is clear from Table 1, there was little difference in the physical properties between the early, middle, and late stages of production, and the core had a high core-sheath pulling strength of about 80% of the core cutting strength.
The minimum value of the core-sheath pull-out strength, which is particularly problematic, was 3 g or more in all, showing that the adhesion at the core-sheath interface was very good. 20 using a semi-operating machine using the obtained raw cotton
In order to produce a non-woven fabric with g / m ↑ 2, the web was put into a card machine. There was no problem with white powder, and the amount of card shedding was very small, 11 g / ton.

[0025]

[Table 1]

Example 2 2.5 Denier, 51 mm long, strength 3.9 g in the same manner as in Example 1 except that the sheath / core composite ratio was 1/2.
/ T, elongation 48%, crimp number 16 / in, and 2.1 tons of staple were obtained. Despite the thinning of the sheath component to 33.3% by weight, peeling of the sheath component did not occur and good raw cotton and non-woven fabric were obtained. Table 2 shows physical properties such as strength of pulling out the core / sheath of staple (value in the middle stage of raw cotton production process).

Comparative Example 1 2.5 Denier, 51 m in the same manner as in Example 1, except that the composite spinning was performed without using the “fluctuation forming layer”.
An m-length staple was manufactured. The core has a core-sheath drawing strength (value in the middle stage of the raw cotton manufacturing process) of 1.5 g,
In particular, the minimum value was 0.4 g, which included many parts that were easily peeled off, and there was a problem in processability. In fact, white powder was remarkably generated in the carding process, and the amount of fallen was very large at 289 g / ton, and it was judged that it was difficult to produce it on an operational basis.

Comparative Example 2 In the same manner as in Example 2, except that the "fluctuation forming layer" was not used and the composite spinning was performed, 2.5 denier and 51 m were obtained in the same manner.
An m-length staple was manufactured. A considerable degree of peeling was observed in the staple in the crimping process, the core-sheath pulling strength (value in the middle stage of the raw cotton manufacturing process) was 0.7 g, and the minimum value was 0.1 g, which was very low, and the card passing property was low. There was a problem, so I gave up the evaluation.

[0029]

[Table 2]

Example 3 As a sheath component, ethylene content was 32 mol%, and saponification degree was 9
9.9% ethylene-vinyl alcohol having a melting point of 181 ° C. was used as a core component with an intrinsic viscosity [η] = 0.67 dl / g and a melting point of 242 ° C. of 8 mol% isophthalic acid copolymerized polyethylene terephthalate. Sheath / core composite ratio = 1/1 (weight ratio)
Composite spinning was performed in. As a "fluctuation forming layer", a non-woven fabric composed of thin metal wires (Naslon NF-13, manufactured by Nippon Seisen Co., Ltd.) and a wire mesh laminate of 20 mesh were used, and discharged at 280 ° C from a 24 hole mouthpiece and heated at 180 ° C. Through 4
It was wound up at 500 m / min. The obtained conjugate fiber was 75 denier / 24 filament, the strength was 3.0 g / d, the elongation was 38%, and the core-sheath pull-out strength was 3.1 g, which was good. Then, the filament was subjected to false twisting and dyed under the following conditions. No peeling of the sheath component was observed in the subsequent step. Dyeing conditions Dye Sumikaron Blue S-3RF 2% owf Dispersant Nikkasan Salt # 7000 0.5g / l pH adjuster Ammonium sulfate 1g / l Acetic acid (48%) 1cc / l Bath ratio: 50: 1 Temperature: 115 ° C Time: 40 minutes Reduction cleaning Hydrosulfide 1g / l Sodium hydroxide 1g / l Amylazine D (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1g / l Bath ratio: 50: 1 Temperature: 80 ° C Time: 20 minutes

Comparative Example 3 A fiber of 75 denier / 24 filament was obtained by spinning in the same manner as in Example 3 except that the "fluctuation forming layer" was not used. The core-sheath pull-out strength of the fiber was 1.2 g. Then, the filament was false twisted and dyed under the same conditions as in Example 3, but the sheath component was considerably peeled off.

Comparative Example 4 Intrinsic viscosity [η] = 0.67 dl / g as core component, melting point 25
A polyethylene terephthalate of 5 ° C., a melt index MI = 20 as a sheath component, and a high-density polyethylene having a melting point of 132 ° C. are used, and the core forming nozzle is a rice type variant of the composite fiber described in JP-A-4-100920. Manufacturing,
An attempt was made under the same spinning conditions as in Example 1 (a spinneret of 0.25 mmφ and 1000 holes, 295 ° C., 1000 m / min). However, since the polymer forming the core portion tends to be a perfect circle, it is difficult to make the outer circumference of the core component 1.2 times the outer circumference of the assumed perfect circle of the core component.
Instead, a small pack with 48 holes and a spinning temperature of 28
By lowering the temperature to 8 ° C., it was possible to obtain a core-sheath composite fiber in which the outer circumference of the core component was 1.2 times the outer circumference of the assumed perfect circle of the core component. The average core-sheath pulling strength of this fiber is 2.
The value was 2 g / d and the minimum value was 0.9 g / d, which was a low value as compared with the fibers obtained in the examples.

Example 4 2.5 mol% of 5-sulfoisophthalic acid was copolymerized as a core component, intrinsic viscosity [η] = 0.55 dl / g, melting point 25
Polyethylene terephthalate at 0 ° C., polymethylpentene (MX001, manufactured by Mitsui Petrochemical Co., Ltd.) having a melt index MI = 26 and a melting point of 235 ° C. as a sheath component were used, and composited at a sheath / core composite ratio = 1/9. 293 ° C, 1000m /
Composite spinning was performed in minutes. 325 as "fluctuation formation layer"
Three metal meshes of mesh, 100 mesh and 20 mesh were laminated and used. Then, stretching is performed under the conditions of a roller temperature of 80 ° C., a plate temperature of 140 ° C. and a stretching ratio of 3.0 times.
Fibers of 75 denier / 24 filaments were obtained. Despite the very thin skin of the sheath component being 10% by weight, no peeling of the sheath component was observed. A Sum-Snit was knitted using the fibers and dyed under the following conditions. Dyeing conditions Cationic dye: Cathilon Brill Red 4GH200 2% owf Auxiliary agent: Sodium sulfate 2g / l Acetic acid 1% owf Sodium acetate 0.5% owf Bath ratio: 50: 1 Temperature: 125 ° C Time: 40 minutes Reductive washing Hydrosulfide 1g / l Ammonia water 1 g / l Amylazine D (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 1 g / l Bath ratio: 50: 1 Temperature: 70 ° C Time: 20 minutes Only polyethylene terephthalate in the core was dyed, but low Since the refractive index of polymethylpentene was used as the sheath, the surface reflection of the fiber was reduced, and a clear and glossy knitted fabric could be obtained.

Reference Example 1 The core / sheath pull-out strength of the composite fiber of which the sheath part is made of polyethylene and the core part is made of polypropylene and the sheath / core composite ratio is 1/1 is about 3 g / d, and the minimum value is about 2 g. Was / d. Further, the amount of shed during the carding process was measured in the same manner as in Example 1 and found to be 32 g / ton.

[0035]

According to the present invention, even if the polymers constituting the composite fiber are incompatible with each other, a fiber free from interfacial peeling in the fiber manufacturing process, fibrillation in the processing process, and generation of white powder can be obtained.

[Brief description of the drawings]

FIG. 1 is an example view showing a cross section of a spinning pack used in the present invention.

FIG. 2 is a photograph showing an example of a cross-sectional shape of the core-sheath type composite fiber of the present invention.

FIG. 3 is a photograph showing that the core component and the sheath component are mixed in the present invention, and is a photograph showing a side surface of the fiber in which the sheath component is dissolved and removed.

[Explanation of Codes] a: Composite plate b: Composite plate c: Fluctuation forming layer d: Base A: Thermoplastic polymer-A flow B: Thermoplastic polymer-B flow

Claims (2)

[Claims] 1. A core-sheath type composite fiber comprising thermoplastic polymers A and B which are incompatible with each other, wherein the polymers A and B are mixed at a core-sheath interface. fiber. 2. A method for producing a core-sheath type composite fiber, which comprises discharging a core-sheath composite flow composed of thermoplastic polymers A and B which are incompatible with each other through a fluctuation-forming layer and then discharging from a nozzle. .