JPH07216656A - Production of hot-melt conjugate fiber - Google Patents

Abstract

PURPOSE:To provide a process capable of melt-spinning a hot-melt conjugate fiber weldable at low temperature without generating the adhesion between the single filaments in high workability. CONSTITUTION:A core-sheath conjugate fiber containing a polyester A having a crystal melting point of 50-80 deg.C as the sheath component and a polyester B having a crystal melting point of >=200 deg.C as the core component is produced by melt-spinning. In this process, a polyester having a melt-viscosity of 2,500-5,000 poise at the melt-spinning stage is used as the component B and the spun yarn is cooled with a cooling air flow of <=20 deg.C blown against the spun yarn at a position within 25mm from the end row of the orifices bored on the spinneret.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a core-sheath type heat-bondable composite fiber having a sheath having heat-adhesive polyester and a core having fiber-forming polyester. Relates to a method for producing a heat-bondable composite fiber which can be bonded at a relatively low temperature.

[0002]

2. Description of the Related Art In recent years, in roofing materials, interior materials for automobiles, non-woven fabrics used for carpet base fabrics, etc., and fiber structures such as pillows and mattresses, thermal bonding has been performed in order to bond constituent fibers (main fibers) to each other. Natural fibers are widely used. And as the main fiber, polyester fibers having relatively low cost and excellent physical properties are most often used, and since the heat-adhesive fibers for adhering this are also preferably polyester-based, various polyester-based heat-adhesive fibers and A polyester fiber structure and the like bonded using the same has been proposed (for example, US Pat. No. 4,129,675).

These heat-adhesive fibers are used alone when the adhesive component has a fiber-forming ability by itself,
When there is no fiber forming ability or when the strength is low even when formed into a fiber, a core-sheath type composite fiber in which a component having thermal adhesiveness is arranged in a sheath and a component having fiber forming ability is arranged in a core is used.

The practical bonding temperatures of these polyester heat-bondable fibers are 110 ° C., 130 ° C., 210 ° C.,
Although those of 220 ° C. level were generally used, recently, for example, for papermaking, there has been a demand for thermo-adhesive fibers capable of bonding at a low temperature of 80 ° C. or lower. However, such a composite fiber having a low practical adhesion temperature of 80 ° C. or less is likely to cause adhesion between single yarns during melt spinning, and thus melt spinning is difficult and cannot be obtained with good operability. .

[0005]

DISCLOSURE OF THE INVENTION In view of the above, the present invention eliminates the adhesion of a single yarn that occurs when melt-spinning a thermoadhesive conjugate fiber, and improves the operability of a thermoadhesive conjugate fiber of good quality. The technical problem is to provide a manufacturing method well.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the inventors have specified the melt viscosity of polyester as a core component of a core-sheath type composite fiber, and The present invention has been found out that by cooling from near by a cooling air of 20 ° C. or less, a composite fiber having a low practical adhesion temperature of 80 ° C. or less can be melt-spun without causing adhesion between single yarns. That is, according to the present invention, when a core-sheath type composite fiber having polyester A having a crystal melting point of 50 to 80 ° C as a sheath component and polyester B having a crystalline melting point of 200 ° C or more as a core component is melt-spun, it is melted as a B component. Melt viscosity at spinning is 2500
A heat-adhesive composite characterized by blowing a cooling air of 20 ° C or less onto the spun yarn from a position within 25 mm from the end row of the orifice holes formed in the spinneret, using polyester of ~ 5000 poise. The gist is the method for producing fibers.

The present invention will be described in detail below. In the present invention, first, polyester A having a crystal melting point of 50 to 80 ° C.
Is a sheath component, and a core-sheath type composite fiber having polyester B having a crystalline melting point of 200 ° C. or more as a core component is melt-spun. Examples of the polyester A having thermal adhesiveness and a crystal melting point of 50 to 80 ° C. used for the sheath component include those obtained from a linear aliphatic dicarboxylic acid component and an aliphatic diol component, and a linear aliphatic Specific examples of the dicarboxylic acid include succinic acid, glutaric acid, adipic acid, sebacic acid, azelaic acid and decane.
-1,10-dicarboxylic acid, tetradecane-1,14-dicarboxylic acid, octadecane-1,18-dicarboxylic acid and ester-forming derivatives thereof, and decane-1,1 in terms of cost.
0-dicarboxylic acid is particularly preferred. Aliphatic diol components include ethylene glycol, propylene glycol, 1,
4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol and the like can be mentioned.

Two or more of these dicarboxylic acid and diol components may be used in combination, and terephthalic acid, isophthalic acid, phthalic acid, 5-sodium sulfoisophthalic acid, hydroxybenzoic acid, and 1,
4-Cyclohexanedimethanol or the like may be used in combination as a copolymerization component, or additives such as a matting agent, a stabilizer and a colorant may be added. Further, in addition to the above combinations, those obtained by polymerizing or copolymerizing an aliphatic hydroxycarboxylic acid may be used.

Examples of the polyester B having a fiber-forming ability and a crystal melting point of 200 ° C. or more, which is used as a core component, include polyethylene terephthalate and polybutylene terephthalate, which are aliphatic dicarboxylic acids within a range not impairing the effects of the present invention. Alternatively, an aliphatic diol may be copolymerized, and additives such as a matting agent, a stabilizer and a colorant may be added.

The melt viscosity of polyester B must be 2500 to 5000 poise. If the melt viscosity is less than 2500 poise, the deformation rate of the yarn during cooling is high, sufficient cooling is not performed in the cooling region, and adhesion occurs between single yarns, resulting in frequent yarn breakage during the drawing process. In addition, the yarn spun from all the spinning holes may become a single ribbon, which may not be used in the drawing step. Exceeding 5000 poise requires extrusion at high pressure, but since the viscosity difference with polyester A as the sheath component is large, discharge of polyester B as the sheath component and polyester A as the core component discharged from the same spinning hole. Streaks occur and the yarn becomes less uniform.
Furthermore, when this yarn is stretched, yarn breakage frequently occurs.

In the present invention, the above-described polyester A is used as a sheath component and polyester B is used as a core component for composite spinning.
From the viewpoint of adhesive strength and strength, it is preferable to set the core: sheath ratio (cross-sectional area ratio) to 7: 3 to 3: 7.

Next, in the present invention, the spun yarn is blown with a cooling air of 20 ° C. or lower from a position within 25 mm from the end row of the orifice holes formed in the spinneret. It is necessary to keep the temperature of the cooling air below 20 ° C. When the temperature of the cooling air exceeds 20 ° C, the yarn on the blowing side of the cooling air is cooled sufficiently, but at a position away from the blowing side of the cooling air. The yarn is not sufficiently cooled, and the solidification point upon cooling becomes uneven, so that the yarn sways due to the accompanying flow, and the single yarns come into close contact with each other.

When the cooling air is blown from a position more than 25 mm away from the end row of the orifice holes, the cooling air is blown from the side where the cooling air is blown at a normal cooling air blowing speed (4 to 9 m / sec). Since the cooling air does not sufficiently penetrate the yarns at the distant positions, sufficient cooling is not performed, and the close contact between the single yarns occurs as described above. Also, when the cooling air blowing speed is increased above the normal blowing speed, the cooling air penetrates to the yarns located away from the cooling air blowing side, but the yarns on the blowing side become violently shaken, and the single yarn It is not preferable because adhesion occurs between them.

The position where the cooling air is blown under the above conditions is
The position may be 10 to 300 mm below the surface of the spinneret, and may be appropriately selected within this range so as not to cause thickness unevenness in the yarn.

As the cooling air blowing method, there are an annular blowing method in which the cooling air is blown from an annular blowing device installed on the outer circumference of the orifice hole, a lateral blowing method in which the cooling air is blown horizontally to the yarn from one direction, and the like. However, the annular spraying method is preferable. Further, a center spraying method can also be used in which an annular spraying device is provided at the center of the yarn group and the yarns are sprayed toward the outer yarns from the inner yarns.

The yarns cooled as described above are once wound up, and then aligned so as to have a denier of 80 to 1,000,000, and drawn at a drawing temperature not higher than the melting point of the sheath component by using a usual drawing machine at a speed of 70. It is stretched at a rate of 150 m / min and a draw ratio of 2.5 to 3.5.

[0017]

According to the present invention, polyester B as a core component
By setting the melt viscosity to 2500 to 5000 poise, the deformation rate of the yarn at the time of forming the yarn can be made sufficiently small, so that sufficient cooling in the cooling region becomes possible. Furthermore, by blowing a cooling air of 20 ° C or less from a position within 25 mm from the row of the end of the orifice hole, the cooling air penetrates to the yarns located far from the blowing side of the cooling air, and the yarns are rapidly cooled. Therefore, the close contact between the single yarns is prevented. Therefore, the thermoadhesive conjugate fiber capable of adhering at a low temperature of 80 ° C. or less is produced with good operability.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples. (1) Crystal melting point Measured at a temperature rising rate of 20 ° C / min using a differential scanning calorimeter DSC-2 type manufactured by Perkin Elmer. (2) Melt viscosity A polymer was melted at a predetermined temperature using a flow tester (CFT-500) manufactured by Shimadzu Corporation, and the viscosity when the shear rate of the polymer discharged from the nozzle was 1000 sec ^-1 was defined as the melt viscosity. (3) Relative viscosity of polyester It was measured at a concentration of 0.5 g / dl and a temperature of 20 ° C. using a mixed solvent of equal weight of phenol and carbon tetrachloride. (4) Adhesion between single yarns The state of the undrawn yarn after spinning was visually observed and evaluated in the following three stages. ○: There is no close contact. Δ: A part was in close contact. X: Most of the fibers were in close contact with each other and formed into a ribbon shape, which was not a fiber that can be used in the stretching step. (5) Cooling air temperature It was measured with a digital thermometer HL-300 (E) manufactured by Adachi Keiki Co., Ltd. at a position 10 mm from the blowing surface of the cooling air.

Example 1 Polyester obtained from decane-1,10-dicarboxylic acid and 1,6-hexanediol and having a crystal melting point of 68 ° C. was used as component A, and polyethylene terephthalate having a relative viscosity of 1.40 (melting point) was used.
Melt viscosity at 262 ℃, spinning temperature 290 ℃ 3400 poise)
As component B, the cross-sectional area ratio is 1: 1 and the spinning temperature is 290.
Spinning was performed from a spinneret having 429 holes in 3 rows of 3 ° C. at a discharge rate of 206 g / min. An annular spraying device is provided 50 mm below the die surface, and from the position 15 mm away from the end row of orifice holes.
After cooling with a cooling air of 18 ° C. to solidify by cooling, an oil agent was applied, and the product was taken up at a spinning speed of 800 m / min and wound up. Then, the undrawn yarns were aligned so as to have a denier of 100,000 and drawn 3.0 times at a drawing speed of 100 m / min and a drawing temperature of 60 ° C. Table 1 shows the evaluation results of the adhesion between single yarns and the drawability of the undrawn yarn after spinning.

Examples 2 to 3 and Comparative Examples 1 to 6 Except that the melt viscosity of polyester B, the distance from the row of the ends of the orifice holes sprayed with the cooling air, and the temperature of the cooling air were changed as shown in Table 1. The same procedure as in Example 1 was performed. Table 1 also shows the evaluation results of the adhesion between single yarns and the drawability of the undrawn yarns after spinning.

[0021]

[Table 1]

Example 4 Example 1 was repeated except that the polyester having a crystal melting point of 56 ° C. obtained from sebacic acid and 1,4-butanediol was used as the component A. As a result, the single yarns did not adhere to each other, and good spinning was possible. When the obtained undrawn yarn was drawn 3.0 times at a drawing temperature of 40 ° C, no yarn breakage occurred.
It could be stretched smoothly.

Comparative Example 7 Example 1 except that polyester A having a crystal melting point of 41 ° C. obtained from adipic acid and 1,5-pentanediol was used as the component A
I went the same way. As a result, the single yarns adhered to each other during the spinning, and the spinning could not be performed.

[0024]

INDUSTRIAL APPLICABILITY According to the present invention, in the spinning of a core-sheath type composite fiber having a polyester having a crystalline melting point of 50 to 80 ° C. as a sheath component and a polyester having a crystalline melting point of 200 ° C. or more as a core component, a single yarn It is possible to carry out melt spinning without causing adhesion between them, and it is possible to produce a heat-adhesive conjugate fiber having good quality and capable of adhering at low temperature with good operability.

Claims (1)

[Claims] 1. When melt-spinning a core-sheath type composite fiber comprising polyester A having a crystalline melting point of 50 to 80 ° C. as a sheath component and polyester B having a crystalline melting point of 200 ° C. or more as a core component, melt spinning is performed as a B component. Using polyester with a melt viscosity of 2500-5000 poise at the time of ejection, blow the cooling air of 20 ° C or less to the spun yarn from a position within 25 mm from the end row of the orifice holes formed in the spinneret. A method for producing a heat-adhesive conjugate fiber, which is characterized.