JP2003328234A - Polyester-based hot melt hollow conjugate short fiber and nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester-based hot melt hollow conjugate short fiber suitable for obtaining a nonwoven fabric having bulkiness, flexibility and heat resistance. <P>SOLUTION: This polyester-based hot melt hollow conjugate short fiber is a side by side type conjugate fiber constituted by a polyester having ethylene terephthalate main recurring unit and a low melting point polyester having 20-80°C glass transition temperature, 90-130°C crystallization temperature and 130-180°C melting point, and has a continuous hollow part having 10-30% void rate in fiber axis direction. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-adhesive fiber for thermally adhering a main fiber in a non-woven fabric field such as a dry non-woven fabric or a wet non-woven fabric composed of short fibers, which has flexibility, bulkiness and heat resistance. The present invention relates to a polyester-based heat-bondable hollow composite staple fiber suitable for obtaining a nonwoven fabric and a nonwoven fabric obtained therefrom.

[0002]

2. Description of the Related Art Synthetic fibers, particularly polyester fibers, are indispensable as clothing and industrial materials because of their excellent dimensional stability, weather resistance, mechanical properties, durability and recyclability. And is often used in the field of non-woven fabrics.

In the field of non-woven fabrics made of this polyester fiber, recently, a non-woven fabric having flexibility, bulkiness and heat resistance has been desired. Conventional non-woven fabrics made of polyester-based short fibers use heat-adhesive composite short fibers for heat-bonding the main fibers.Generally, polyethylene terephthalate is used for the core and isophthalic acid is used for the sheath. Thermoadhesive composite staple fibers having a polymerized low melting point polymer are used.

However, since polyethylene terephthalate used as the core component of the heat-adhesive short composite fibers has a high rigidity of the polymer itself, it is difficult to impart flexibility to the nonwoven fabric. As a method of solving such a problem, by narrowing the fineness of the heat-adhesive composite staple fiber,
Many attempts have been made to reduce the rigidity of fibers and impart flexibility to nonwoven fabrics.

However, if a fine fiber having a fineness of about 1 dtex is to be obtained in the spinning process, the operability is deteriorated and the spinning process is complicated, so that the heat-adhesive composite staple fiber is easily obtained. It was difficult.

On the other hand, in order to impart heat resistance to the nonwoven fabric,
In Japanese Unexamined Patent Publication No. 7-119011 and Japanese Unexamined Patent Publication No. 9-132850, a core is made of polyethylene terephthalate and a sheath is made of a terephthalic acid component, an aliphatic lactone component, an ethylene glycol component and a 1,4-butanediol component. It has been proposed to use thermoadhesive composite staple fibers having the low melting point polymer.

Such heat-bondable composite short fibers have better heat resistance than conventional polyester heat-bondable composite short fibers, but since the fiber shape is a core-sheath structure, the bulkiness of the resulting nonwoven fabric is high. It was inferior in sex and had insufficient flexibility.

Further, in order to impart heat resistance and flexibility to the non-woven fabric, Japanese Patent Laid-Open No. 2001-115340 discloses that polytrimethylene terephthalate is used for the core and terephthalic acid component, aliphatic lactone component, ethylene glycol are used for the sheath. Ingredients and 1,4
It has been proposed to use thermoadhesive composite staple fibers having a low melting point polymer copolymerized with a butanediol component.

The heat-adhesive conjugate short fibers are better than the conventional polyester heat-adhesive conjugate short fibers in heat resistance and flexibility, but the fiber shape is also a core-sheath structure, The resulting non-woven fabric was inferior in bulkiness. As described above, the present situation is that a thermoadhesive conjugate short fiber capable of imparting flexibility, bulkiness and heat resistance to a non-woven fabric has not yet been obtained.

[0010]

DISCLOSURE OF THE INVENTION The present invention solves the above problems and provides a heat-adhesive hollow composite staple fiber capable of obtaining a nonwoven fabric having excellent flexibility, bulkiness and heat resistance, and the same. It is a technical subject to provide a non-woven fabric.

[0011]

Means for Solving the Problems The inventors of the present invention have made extensive studies in order to solve the above problems and arrived at the present invention. That is, the present invention has the following configurations. (1) A side-by-side type composite fiber composed of a polyester whose main repeating unit is alkylene terephthalate and a low melting point polyester having a glass transition point of 20 to 80 ° C, a crystallization temperature of 80 to 130 ° C and a melting point of 130 to 180 ° C. A polyester-based heat-adhesive hollow composite staple fiber having a hollow portion continuous in the fiber axis direction and having a hollow ratio of 10 to 30%. (2) Copolymerized polyester in which the low melting point polyester constituting the conjugate fiber contains a terephthalic acid component, an ethylene glycol component and a 1,4-butanediol component, and also contains an adipic acid component and / or an aliphatic lactone component. The polyester-based heat-adhesive hollow composite short fiber according to claim 1. (3) A nonwoven fabric comprising the polyester-based heat-bondable hollow composite short fiber according to (1) or (2).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The heat-adhesive hollow composite staple fiber of the present invention is a side-by-side composite fiber composed of a polyester (polyester A) whose main repeating unit is alkylene terephthalate and a low melting point polyester (polyester B). In the present invention, polyester is used for both components of the conjugate fiber in order to prevent the polymers from peeling off and the operability from being deteriorated in the yarn making process and the processing process.

In the present invention, it is preferable to use polyethylene terephthalate (hereinafter abbreviated as PET) as the polyester A in consideration of spinning operability, raw cotton physical properties, cost and the like. Polyester B is a low-melting point polyester and is melted by heat treatment, but polyester A is a component that forms the nonwoven fabric together with the main fibers that form the nonwoven fabric. Therefore, as long as the effect of the obtained nonwoven fabric is not impaired, diol components such as 1,4-butanediol and 1,6-hexanediol, bisphenol A, etc.
Aromatic diol components such as ethylene oxide adducts of
It may be a copolymer of an aliphatic dicarboxylic acid component such as adipic acid or sebacic acid, an aromatic dicarboxylic acid component such as isophthalic acid, etc., and further, a stabilizer, a fluorescent agent, a pigment, an antibacterial agent, a deodorant, a toughening agent. Etc. may be added.

On the other hand, polyester B has a glass transition point (Tg) of 20 to 80 ° C. and a crystallization temperature (Tc) of 80 to.
It is necessary that the temperature is 130 ° C and the melting point (Tm) is 130 to 180 ° C. If the Tg is less than 20 ° C, adhesion between the single yarns will occur during melt spinning, resulting in poor spinnability. On the other hand, if the Tg exceeds 80 ° C, it will be necessary to perform stretching at a high temperature in the spinning process. At the same time as plastic deformation, partial crystallization starts and yarn breakage occurs, and the drawability decreases.

If the Tc of the polyester B is less than 80 ° C., crystallization will proceed in the hot drawing step, making it difficult to reconstruct a stable crystal structure in the next heat treatment step. On the other hand, when Tc exceeds 130 ° C., Tm also rises in parallel, and heat treatment at a high temperature is required, which easily causes decomposition of the component A during the heat-bonding process and is economically disadvantageous.

Furthermore, the Tm of polyester B is 130 ° C.
If it is less than the above range, even if it is made into a fiber, heat resistance cannot be obtained when used in a high temperature atmosphere. On the other hand, Tm is 1
If it exceeds 80 ° C., heat treatment at a high temperature is required when forming a nonwoven fabric, which is economically disadvantageous, which is not preferable. Further, the melting point difference from the polyester A is also reduced, the processability is deteriorated, and the obtained nonwoven fabric is poor in flexibility.

Polyester B is specifically a copolymer containing a terephthalic acid component, an ethylene glycol component and a 1,4-butanediol component and at least one component of an adipic acid component and an aliphatic lactone component. It is polyester. The polyester having a low melting point as described above can be obtained by adjusting the copolymerization amount of these.

First, by containing a terephthalic acid component, an ethylene glycol component and a 1,4-butanediol component, Tm can be set to about 180 ° C. At this time, if the molar ratio of the ethylene glycol component and the 1,4-butanediol component is 50/50, Tm can be minimized. Furthermore, by copolymerizing at least one of the adipic acid component and the aliphatic lactone component, Tm can be further reduced.

By copolymerizing the 1,4-butanediol component, flexibility can be imparted to the resulting nonwoven fabric. Therefore, it is preferable to set the molar ratio of the ethylene glycol component and the 1,4-butanediol component to 40/60 to 60/40 in consideration of the above relationship with Tm.

Furthermore, when the aliphatic lactone component is copolymerized alone, it is preferably 10 to 20 mol% with respect to the total acid components (the total of the terephthalic acid component and the aliphatic lactone component). When the content of the aliphatic lactone component is less than 10 mol%, the crystallinity is improved, but the Tm is likely to exceed 180 ° C., and when forming a nonwoven fabric, heat treatment at a high temperature is required, and the workability is deteriorated, which is not preferable. Also, 2
When it exceeds 0 mol%, the temperatures of Tg, Tc, and Tm become low, and adhesion tends to occur during spinning and the spinnability tends to deteriorate. As the aliphatic lactone component that can satisfy the above-mentioned thermal characteristics, a lactone having 4 to 11 carbon atoms is preferable, and preferable lactones include ε-caprolactone and δ-valerolactone.

Even when the adipic acid component is copolymerized alone, it is preferably 10 to 20 mol% with respect to the total acid components (the total of the terephthalic acid component and the adipic acid component). Also, when the aliphatic lactone component and the adipic acid component are used in combination, it is preferable that the content be 10 to 20 mol% with respect to the total acid component. Outside of these ranges, it is not preferable for the same reason as in the case of the above-mentioned aliphatic lactone component.

Polyester B, which is a low melting point copolyester, contains a small amount of a copolymerization component such as isophthalic acid, phthalic acid, sebacic acid, diethylene glycol and triethylene glycol within a range not impairing the effects of the present invention. May be.

Next, the fiber of the present invention is obtained by bonding polyester A and polyester B in a side-by-side type, and has a hollow portion. With such a shape, when polyester B, which is a low-melting polyester, is melted, only polyester A has a C-shaped cross-sectional shape, and a nonwoven fabric excellent in bulkiness can be obtained.

The composition ratio (A / B) of polyester A and polyester B is preferably 40/60 to 60/40 in volume ratio, and more preferably 45/55 to 55/45. When the proportion of the polyester A exceeds 60%, the thermal adhesiveness is deteriorated and the nonwoven fabric performance is deteriorated, which is not preferable. On the other hand, the proportion of polyester A is 40%
If less than, polyester A after melting polyester B
The resulting C-shaped product is small, and the resulting nonwoven fabric lacks bulkiness and becomes paper-like, which is not preferable.

The heat-adhesive hollow composite staple fiber of the present invention must have a hollow portion continuous in the fiber axis direction, and the hollow ratio, which is the ratio of the hollow portion, must be 10 to 30%.
The hollow ratio means the cross-sectional area of the hollow portion in the cross-sectional area of the fiber in the direction perpendicular to the fiber axis direction. Hollow rate is 10%
When it is less than 1, the bulkiness of the resulting nonwoven fabric becomes insufficient. On the other hand, if the hollow ratio exceeds 30%, hollow cracks will occur during melt spinning, and spinning operability and quality will deteriorate, which is not preferable.

The heat-adhesive hollow composite short fibers of the present invention are obtained by cutting yarns into short fibers, but the fiber length is not particularly limited, and is 3 to 150 depending on the application.
It may be cut into about mm.

The method for producing the heat-bondable hollow composite staple fiber of the present invention will be described. First, the polyester A and the polyester B described above are melt-spun by a commonly used side-by-side type composite hollow spinning device to obtain a side-by-side type heat-bondable hollow composite undrawn yarn. Next, the unstretched yarn is bundled, then stretched by a conventional method, and if necessary, mechanical crimps are imparted by a push-in type crimper, a finishing oil is imparted, and then cut into 3 to 150 mm depending on the application, and heat-bonded. Hollow composite short fibers.

Next, the nonwoven fabric of the present invention will be described.
The nonwoven fabric of the present invention contains the above-mentioned polyester-based heat-adhesive hollow composite short fibers of the present invention. That is, the nonwoven fabric of the present invention may be composed of only the short fibers of the present invention or may be composed of the short fibers of the present invention and a main fiber.
Above all, it is preferable to mix the heat-adhesive hollow composite short fibers of the present invention with the main fibers so that the ratio is 10 to 50% by mass, preferably 25 to 50% by mass. In addition, although the main fiber is not particularly limited, it is preferable to use a polyester fiber, and it is preferable to use a fiber having a hollow portion in order to improve bulkiness.

The method for producing the nonwoven fabric of the present invention will be described. Only the heat-bondable hollow composite short fibers of the present invention or the heat-bondable hollow composite short fibers and the main fiber are mixed and subjected to a card machine to prepare a web. This web was heated to a temperature of at least Tm of the low melting point component of the heat-bondable hollow composite short fiber, Tm + 5 of the low melting point component.
The low melting point component is melted by heat treatment with a heat treatment apparatus set to a temperature of 0 ° C. or less, and bonded to form a nonwoven fabric. Then, after once cooling to room temperature, crystallization heat treatment is performed at a temperature of Tc of the low melting point component or higher and Tc of the low melting point component of + 30 ° C. or lower to promote the crystallinity of the low melting point component of the heat-adhesive hollow composite short fiber. , To obtain the nonwoven fabric of the present invention. In this case, the needling process may be performed before the heat treatment. As the heat treatment device, a hot air dryer, a rotary drum dryer or the like is used.

[0030]

EXAMPLES Next, the present invention will be specifically described by way of examples. The performance evaluations in the examples are measured according to the following methods. (1) Tg, Tc, and Tm Using a differential scanning calorimeter DSC-7 type manufactured by Perkin Elmer Co., Ltd., measurement was performed at a temperature rising rate of 20 ° C./min. (2) Single yarn fineness It was measured by the method of JIS L-1015. (3) Unit weight and density of nonwoven fabric It was measured by the method of JIS P-8142. (4) Hollow ratio (%) Of 30 monofilaments constituting the fiber, the cross-sectional area of the hollow part in the cross-sectional area of the fiber when cut in the direction perpendicular to the fiber axis direction in 30 selected arbitrarily Calculated by the following formula,
The average value was used. Hollow ratio (%) = (A / B) × 100 A: Cross-sectional area of hollow part B: Cross-sectional area of whole monofilament (5) Heat resistance of non-woven fabric (The following non-woven fabric preparation conditions are for evaluation of heat resistance only) Utilization) a: Conditions for making non-woven fabric Main fiber: Polyester (PET) short fiber 4.4d
tex × 51 mm Mixing ratio: Main fiber / Heat-bonding hollow composite short fiber = 70 /
30 (mass ratio) Treatment temperature: Heat-adhesive hollow composite short fiber polyester B (Tm + 30 ° C.) × 1 minute Crystallization treatment: 110 ° C. × 20 minutes Marking: 50 g / m ² b: Strength of nonwoven fabric at room temperature (Measurement temperature: 23 ° C.) The nonwoven fabric obtained in a was cut into a strip having a width of 2.5 cm and a length of 15 cm to prepare a sample. This sample was stretch-cut at a measuring temperature of 23 ° C. using a UTM-4 type Tensilon manufactured by Orientec Co., Ltd. at a pulling speed of 10 cm / min, and the maximum strength was read. c: Strength of non-woven fabric in high temperature atmosphere (measurement temperature: 110
C.) The non-woven fabric obtained in a) was cut into a strip having a width of 2.5 cm and a length of 15 cm to prepare a sample. This sample is placed at temperature 11
After leaving for 1 minute in a 0 ° C constant temperature bath, UT manufactured by Orientec
Tensile speed of 10c using M-4 type Tensilon
It was stretched and cut under the condition of m / min, and the maximum strength was read. d: Strength retention of nonwoven fabric (%) (heat resistance) From the strength of the nonwoven fabric at room temperature (A) and the strength of the nonwoven fabric at high temperature (B), the strength retention at high temperature was calculated by the following formula. . 50% strength retention in high temperature atmosphere
The above was regarded as good heat resistance. Strength retention rate (%) = (B / A) × 100 (6) Flexibility (rigidity) of the nonwoven fabric It was measured by the following method according to JIS L-1096. Sample width 10 cm, sample length 10 cm using the obtained non-woven fabric
3 sample pieces were prepared and evaluated using a feel meter (MODEL FM-2) manufactured by DAIEI KEIKI.
First, a sample piece was placed on a slit with a width of 15 mm, and when the arm pushed the sample between the slits, the maximum force required was measured at 4 points in the vertical and horizontal directions on the front and back sides of the sample, and the total value was obtained. I asked. The average value of three sample pieces was evaluated as the non-woven fabric bending resistance (cN). The bending resistance is 70
A value of cN or less was accepted. (7) Bulkiness of Nonwoven Fabric The obtained nonwoven fabric is cut into a length of 20 cm and a width of 20 cm to prepare 10 samples. Stack 10 samples and load 1 on top
A 90 g plate (25 cm × 25 cm) is placed, the heights of the four corners of the sample are measured, and the average height (h) is determined. The bulkiness was calculated by the following formula. A bulkiness of 30 cm ³ / g or more was accepted. Bulkiness (cm ³ / g) = (20 × 20 × h) / 80 (8) Spinning operability evaluation ○: No yarn breakage, no adhesion between single yarns, good operability ×: Yarn breakage, single yarn interval Occurs on either side of
Poor operability (9) Comprehensive evaluation ◯: Good spinning operability, strong retention of nonwoven fabric in high temperature atmosphere of 50% or more, and bulkiness of 30 cm ³ / g
As described above, the bending resistance is 70 cN or less. X: The spinning operability, the tenacity retention of the nonwoven fabric in a high temperature atmosphere, the bulkiness, and the bending resistance are all inferior.

Example 1 Polyester A having a melting point of 256 ° C. and an [η] of 0.6
As PET 8 and polyester B, 15 mol% of ε-caprolactone was copolymerized with respect to the total acid component, and 60 mol% of 1,4-butanediol was copolymerized with respect to the glycol component.
Using a low melting point copolyester of g40 ° C., Tc94 ° C. and Tm160 ° C., a melt composite spinning device was used to spin at a spinning temperature of 270 ° C. and a discharge rate of 642 g / min.
It was taken out at m / min to obtain an undrawn yarn of a side-by-side type hollow composite fiber. The composition ratio (A / B) of polyester A and polyester B was 50/50 by volume. Then, the undrawn yarn was converged on a tow of 110,000 dtex, drawn at a draw ratio of 3.8 times, and drawn at a drawing temperature of 55 ° C., crimped with a push-in type crimper, and then cut to obtain a single yarn fineness of 4 A heat-adhesive hollow composite short fiber having a fiber length of 51 mm with a fiber length of 0.4 dtex was obtained. Furthermore, 30% by mass of the obtained heat-adhesive hollow composite short fibers and, as a main fiber, a fineness of 6.6.
70% by mass of hollow composite short fibers with dtex and fiber length of 51 mm
After being mixed into a card and made into a web by a card machine, it is heat-treated at 190 ° C. for 1 minute in a continuous heat treatment machine, cooled once, and then heat-treated at a crystallization temperature of 110 ° C. for 20 minutes to give a basis weight of 20.
A non-woven fabric of 0 g / m ² was obtained. (For evaluation of heat resistance, a nonwoven fabric was prepared under the above conditions.)

Example 2 As a copolymerization component of polyester B, heat-adhesive hollow composite short fibers were prepared in the same manner as in Example 1 except that adipic acid (copolymerization amount: 15 mol%) was used instead of ε-caprolactone. And obtained a non-woven fabric.

Examples 3 to 4 The copolymerization amount of ε-caprolactone of polyester B is shown in Table 1.
And the heat treatment temperature in the continuous heat treatment machine of the card web was changed to 205 ° C. in Example 3 and 185 ° C. in Example 4 to obtain a heat-bondable hollow composite short fiber in the same manner as in Example 1. A non-woven fabric was obtained.

Comparative Example 1 Polyester A having a melting point of 230 ° C. and a P of [η] of 0.92
A heat-adhesive hollow composite short fiber and a nonwoven fabric were obtained in the same manner as in Example 1 except that the TT was changed.

Comparative Example 2 The copolymerization amount of ε-caprolactone of polyester B is shown in Table 1.
The thermal adhesive hollow composite short fibers and the non-woven fabric were obtained in the same manner as in Example 1 except that the heat treatment temperature was 225 ° C. in the continuous heat treatment machine for the card web.

Comparative Example 3 The copolymerization amount of ε-caprolactone of polyester B is shown in Table 1.
The thermal adhesive hollow composite short fibers and the nonwoven fabric were obtained in the same manner as in Example 1 except that the heat treatment temperature was 170 ° C. in the continuous heat treatment machine for the card web.

Comparative Example 4 As a copolymerization component of polyester B, 40 mol% of isophthalic acid was copolymerized in place of ε-caprolactone to obtain an amorphous copolymerized polyester (Tg 62 ° C., softening point temperature 110).
C.) and the heat treatment temperature of the continuous heat treatment machine for the card web was 150 ° C., to obtain a heat-bondable hollow composite short fiber and a nonwoven fabric in the same manner as in Example 1.

Comparative Example 5 A heat-bondable composite staple fiber and a nonwoven fabric were obtained in the same manner as in Example 1 except that polyester A was used as the core component, polyester B was used as the sheath component, and a core-sheath structure yarn having no hollow portion was used.

Table 1 shows the physical property values and evaluation results of the heat-bondable composite short fibers and nonwoven fabrics obtained in Examples 1 to 4 and Comparative Examples 1 to 5.
2 shows.

[0040]

[Table 1]

[0041]

[Table 2]

As is clear from Tables 1 and 2, Example 1
The heat-adhesive hollow composite staple fibers of Nos. 4 to 4 were excellent in spinnability, and the resulting nonwoven fabric was excellent in heat resistance, bulkiness and flexibility. On the other hand, since the heat-adhesive hollow composite short fibers of Comparative Example 1 had a low hollow ratio, the obtained nonwoven fabric was inferior in bulkiness. In Comparative Example 2, since the copolymerization amount of ε-caprolactone as the copolymerization component of polyester B of the heat-adhesive hollow composite short fiber was small and the Tm was high, the processability was poor, and the obtained nonwoven fabric was inferior in flexibility. Met. In Comparative Example 3, the amount of ε-caprolactone as a copolymerization component of polyester B of the heat-adhesive hollow composite short fiber was large, and Tg
Was low, the fusion occurred during spinning, the hollow ratio was also low, and the obtained nonwoven fabric was inferior in bulkiness. In Comparative Example 4, since the copolymerization component of polyester B of the heat-adhesive hollow composite short fibers was isophthalic acid and was amorphous, the obtained nonwoven fabric was inferior in heat resistance and flexibility. In Comparative Example 5, the cross-sectional shape of the heat-adhesive conjugate short fiber had a non-hollow core-sheath structure, and thus the obtained nonwoven fabric was inferior in bulkiness.

[0043]

EFFECTS OF THE INVENTION According to the heat-adhesive hollow composite short fiber of the present invention, it is possible to obtain a nonwoven fabric having excellent bulkiness, flexibility and heat resistance at the same time, and a nonwoven fabric using the fiber of the present invention is obtained. Can be used in various applications by taking advantage of its excellent performance.

Claims (3)

[Claims] 1. A polyester whose main repeating unit is alkylene terephthalate, and a glass transition point of 20 to 8
0 ° C, crystallization temperature 80-130 ° C, melting point 130-180
A side-by-side type composite fiber composed of a low melting point polyester having a temperature of 0 ° C., having a hollow portion continuous in the fiber axis direction, and having a hollow ratio of 10 to 30%. Hollow composite staple fiber. 2. A low melting point polyester constituting a composite fiber contains a terephthalic acid component, an ethylene glycol component and a 1,4-butanediol component, and an adipic acid component and / or an aliphatic lactone component. The heat-adhesive polyester-based hollow composite staple fiber according to claim 1, which is a polymerized polyester. 3. A non-woven fabric comprising the polyester-based heat-adhesive hollow composite staple fiber according to claim 1 or 2.