JPH11302926A - Polyester-based conjugate fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester-based conjugate fiber having multifunctional properties such as capabilities of giving bulkiness, drape, or the like to cloth or the like and gentle with the environment, in consideration of waste liquid treatment by reducing the weight of a biodegradable polymeric component. SOLUTION: This conjugate fiber is made of two kinds of polyester-based polymers A, B having different dissolving rates from each other as principal components. The polyester-based polymers B having a higher dissolving rate is an aliphatic polyester and is placed in such a way that it exposes itself from at least a part of the fiber surface and it loses 10-100% of its weight by the weight reduction treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester conjugate fiber which has the inherent fiber properties of polyester and is particularly excellent in alkali weight loss properties.

[0002]

2. Description of the Related Art Polyester fibers have been widely used as clothing fibers. The reason is strength,
This is because it is excellent in Young Modulus and can be stretched on a fabric to give a waist. In recent years, functionality has been pursued more,
Aesthetics in the direction that matches humans as much as possible by using irregularly shaped, differently shrink-blend yarns to impart drapeability to the fabric, or by subjecting composite fibers composed of components with different alkali dissolution rates to alkali weight loss treatment The pursuit of materials and products that take advantage of the nature is being pursued. Therefore, at present, the alkali weight reduction treatment is indispensable for imparting bulkiness and drapability to the fabric, and the processing amount of low-molecular-weight polyester discharged from the alkali treatment waste liquid is now enormous.

[0003] Conventional polyester fibers and resins are
Since the decomposition rate in the natural environment is extremely slow and the amount of heat generated during incineration is large, a review from the viewpoint of protection of the natural environment is required. For this reason, in recent years, biodegradable fibers made of aliphatic polyesters have been developed and are expected to contribute to environmental protection. Aliphatic polyester is
Although it is expected to be a fiber material having excellent fiber performance and new characteristics, it has a problem in that it has a low melting point and is brittle by alkali treatment, and thus lacks practicality or has limited applications.

Japanese Patent Application Laid-Open No. Hei 8-209529 proposes a fiber having a streak-like fibril-like surface, in which a blend fiber of a polyester such as polyethylene terephthalate (PET) and an aliphatic polyester is subjected to alkali reduction. ing. However, this fiber has a problem that the strength after the alkali treatment is reduced, and in order to maintain practical strength, the amount of alkali can be reduced only slightly, and in this case, the drape property is reduced. Not even improved.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and reduces the amount of biodegradable polymer components which have multifunctional properties such as imparting bulkiness and drapability to fabrics and the like. Accordingly, an object of the present invention is to provide an environmentally friendly polyester-based composite fiber including waste liquid treatment.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention is a conjugate fiber mainly composed of two kinds of polyester polymers A and B having different dissolution rates from each other, wherein the polyester polymer B having a high dissolution rate is an aliphatic polyester, and at least A gist of the present invention is a polyester composite fiber, which is arranged so as to be exposed on a part of the fiber surface and is reduced by 10 to 100%.

[0007]

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

First, two types of polyester-based polymers A and B constituting the polyester-based conjugate fiber of the present invention, preferably having different dissolution rates in alkali, will be described. In the present invention, as the polyester-based polymer A having a low dissolution rate, PET or polybutylene terephthalate as a main component, or a polyester whose main repeating unit is an ethylene terephthalate or butylene terephthalate unit is employed. In the case of the latter polyester, the content of the ethylene terephthalate unit and the butylene terephthalate unit is preferably at least 85 mol% or more.

Specific examples of the components forming the polyester include dicarboxylic acid components such as sebacic acid, terephthalic acid, isophthalic acid, phthalic acid, glutaric acid, adipic acid, 5-sodium sulfoisophthalic acid and naphthalic acid.
Diol components such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanedimethanol and xylylene glycol No.

In the present invention, as the polyester polymer B having a higher dissolution rate than the polyester polymer A, it is necessary to employ a polymer mainly composed of an aliphatic polyester, and (1) glycolic acid, Hydroxyalkyl carboxylic acids such as lactic acid and hydroxybutyl carboxylic acid; (2) aliphatic lactones such as glycolide, lactide and butyrolactone; (3) ethylene glycol;
Aliphatic diols such as propylene glycol, butanediol and hexanediol; (4) oligomers such as polyalkylene ethers such as diethylene glycol and dihydroxyethylbutane; polyalkylene glycols such as polyethylene glycol, polypropylene glycol and polybutylene ether; (5) succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, aliphatic carboxylic acids such as decanedicarboxylic acid, etc.
A component derived from an aliphatic polyester polymerization raw material as a main component,
That is, the content is 60% by weight or more, and a homopolymer of an aliphatic polyester, a block or random copolymer of an aliphatic polyester, and other components such as an aromatic polyester, a polyether, a polycarbonate, and a polyamide. , Polyurea, polyurethane and the like, and those obtained by copolymerizing and / or mixing 40% by weight or less.

Among these aliphatic polyester-based polymers, polylactic acid-based polymers, such as poly (D-lactic acid)
, Poly (L-lactic acid), a polymer of an optical isomer by D-lactic acid and L-lactic acid or a blend thereof, a copolymer of D-lactic acid and hydroxycarboxylic acid, L-lactic acid and hydroxycarboxylic acid Particularly preferred is a polymer selected from the group of copolymers with an acid or a blend thereof. The reason is that the polylactic acid-based polymer has a softening point of 1
Exceeding 00 ° C, it is possible to have a melting point exceeding 120 ° C with it, and a fiber made of a polylactic acid-based polymer having a melting point exceeding 120 ° C has a normal dyeing temperature of 100 ° C or more. This is because, even when dyeing is performed, the texture does not change, melting, deterioration, or spots occur.

These aliphatic polyester polymers are:
The weight is easily reduced with respect to a heated alkaline solution, and the fiber of the single polymer has a reduced strength and is therefore less practical. Also, it can be a copolymer,
There is a tendency that the greater the blending ratio with the optical isomer, the easier the alkali weight loss. In the case of a polylactic acid-based polymer,
The blend ratio of the D-form to the L-form is a factor that affects heat resistance and biodegradability. As the purity of the L-form decreases with the D-form, the crystallinity decreases and the melting point decreases. In general, copolymerization can improve flexibility and elastic recovery, increase heat shrinkage, control decomposability and glass transition temperature, and improve adhesion with other components.

In the present invention, the dissolution rates of the two polyester polymers A and B are different from each other because the fibers constituting the fabric are reduced in alkali after the formation of the fabric to reduce the bulk density of the fabric. This is for imparting functions such as giving a plump texture and drapability, and further exhibiting silkiness.

The ratio of the dissolution rates of the polyester polymers A and B differ slightly depending on the conditions such as the concentration of the alkaline solution, the temperature and the time. However, the ratio of the polymer B is more than 10 times that of the polymer A. preferable. If it is less than 10 times, the polyester polymer A is also not preferred because the alkali weight loss becomes too large, the target irregularity, it becomes difficult to control the weight loss, and the processing time becomes longer, which tends to be a problem in cost. . Therefore, more preferably, 15 times or more,
Most preferably, it should be 20 times or more.

Further, the polyester-based conjugate fiber of the present invention is a polyester polymer B having a high dissolution rate, that is,
It is necessary that the aliphatic polyester is arranged so as to be exposed at least on a part of the fiber surface. The reason for this is to easily reduce the alkali weight of the aliphatic polyester during the alkali treatment and to suppress the alkali weight loss of the polymer A component. By adopting such a composite form and performing alkali reduction, it becomes easy to make the fiber into an irregular cross-section, ultra-fine, hollow, etc., and the alkali treatment after fabric formation reduces the bulk density of the fabric and makes it more plump. Functionality such as texture and drape can be imparted, and furthermore, silkiness can be imparted.

The composite cross-sectional shape so that the aliphatic polyester is exposed at least on a part of the fiber surface is as follows:
For example, as shown in FIGS. 1 (a) to 1 (k),
The same or different combinations of various cross-section composite cross sections such as a hollow cross section, a core-sheath type, an eccentric core-sheath type, a side-by-side type, a sea-island type, a multi-core type, a radial split type, and a point-symmetric split type can be adopted. .

The conjugate ratio (weight ratio of polyester polymer A / B) of the polyester composite fiber of the present invention is 5/9.
A range of 5 to 95/5 is preferred. Outside this range,
A decrease in yarn production stability, a collapse of the composite cross section, and / or
Alternatively, the structure of the spinneret becomes complicated and the cost increases, which is not preferable. On the other hand, when the proportion of the polyester-based polymer A is low, the weight loss of the fiber itself after the alkali treatment becomes large, and it becomes difficult to control the weight loss, and the strength decreases, which is not preferable. Therefore, a more preferable range of the composite ratio is 30/70 to 90/10, and a most preferable range of the composite ratio is 50/50 to 85/15.

Next, it is necessary that the amount of the polyester polymer B in the polyester composite fiber of the present invention is reduced by 10 to 100%. The reason for this is that, as described above, only the polyester polymer B is alkali-reduced as much as possible, so that even if low-molecular-weight polymers, oligomers, dimers, and the like released from the waste liquid after alkali treatment are discarded, the global environment is not polluted. That's why. This weight loss range is combined with the above-mentioned composite ratio, for example, when the composite ratio is 50/5.
In the case of 0, the weight loss rate of the fiber itself corresponds to a range of 5 to 50%. If the weight loss of the polyester-based polymer B is less than 10%, the alkali weight loss effect as a conjugate fiber is reduced, and no functionality is exhibited. Also, when it exceeds 100%, the weight of the polyester-based polymer A also starts to decrease,
What is attached to the polyester polymer A is mixed into the waste liquid after the alkali treatment, which makes it difficult to treat the released low-molecular-weight polymer and the like, and is not environmentally friendly and cannot be disposed.

In the present invention, if necessary, for example, a heat stabilizer, a crystal nucleating agent, a matting agent, a pigment, a light-fast agent may be added to the above-mentioned polymer containing polyester-based polymers A and B as main components. Various additives such as weathering agents, antioxidants, antibacterial agents, fragrances, plasticizers, dyes, surfactants, surface modifiers, various inorganic and organic electrolytes, fine powders, and flame retardants impair the effects of the present invention. It can be added within the range not present.

The single fiber fineness of the polyester composite fiber of the present invention is preferably selected from 0.5 to 100 denier. When it is less than 0.5 denier, problems such as control of solidification point, increase in accuracy of a die hole, decrease in productivity due to reduction of discharge amount, occurrence of thread breakage, and the like when forming fibers are likely to occur. Is not preferred. On the other hand, if it exceeds 100 denier, spinning and drawing are difficult in the process of producing ordinary long fibers, and special production equipment is separately required, which is undesirably high in cost.

The strength of the polyester composite fiber of the present invention is preferably 1.0 g / d or more. Strength is 1.0 g / d
If it is less than 30, a problem is likely to occur from the viewpoint of insufficient power in practical use. The higher the fiber strength, the more preferable the range of practical use is. The elongation of the fiber is not particularly limited.
~ 80% is preferred. When the elongation is less than 10%, yarn breakage occurs and the drawing operability tends to decrease. Also,
If the elongation exceeds 80%, the dimensional stability after forming the fabric is likely to decrease, so that it is not generally employed.

The polyester-based composite fiber of the present invention can be used alone or in combination with other fibers to produce knitted fabrics, woven fabrics, various composite materials and other structures. When mixed with other fibers, synthetic fibers composed of fiber-forming polymers such as polyester fibers, nylon fibers, acrylic fibers, vinylon fibers, polypropylene fibers, polyethylene fibers, regenerated fibers such as rayon, and semi-synthetic materials such as acetate Fibers and natural fibers such as wool, silk, cotton, and hemp are employed. As a method of blending with synthetic fibers, spinning blending can also be employed.

Next, an example of the method for producing the polyester composite fiber of the present invention will be described, but the present invention is not limited to this method. In order to produce the polyester fiber of the present invention,
Basically, a spinning method and / or a drawing method using a known melt composite spinning apparatus can be applied.

First, the above-mentioned two types of polyester polymers A and B are individually melted and weighed, and a fiber is spun out from a composite spinning apparatus in which the polyester polymer B is arranged on the fiber surface, and after cooling, Apply oil and wind up. Then
A conjugate fiber can be obtained by thermally stretching the wound yarn or by continuously performing thermal stretching without winding. The fiber wound at a high speed does not necessarily need to be thermally drawn. The hot drawing means drawing an undrawn fiber at a temperature equal to or higher than the glass transition temperature and equal to or lower than the softening temperature.

The above melt spinning has a winding speed of 100
Low speed spinning up to 2000 m / min, winding speed 2000-5
High-speed spinning at 2,000 m / min and ultra-high-speed spinning at a take-up speed of 5,000 m / min or more are possible, and a so-called spin draw method in which spinning and drawing are continuously performed is also preferably applicable.

The fiber form of the polyester-based composite fiber of the present invention can be applied not only to a long fiber but also to a short fiber provided with mechanical crimping or the like. Next, a fabric is formed using the composite fiber obtained above. Alternatively, the fabric may be formed after performing false twisting or twisting in order to obtain specifications meeting the purpose. As the form of the fabric,
A woven fabric, a knitted fabric, a nonwoven fabric, or a fibrous structure made of the composite fiber may be any as long as the shape is maintained.

Further, the fabric is subjected to an alkali treatment,
The aliphatic polyester is reduced by 10 to 100% to obtain the polyester composite fiber of the present invention. The alkali treatment is usually performed by converting sodium hydroxide into an aqueous solution of 10 to 50 g / liter, heating the aqueous solution, and heating the aqueous solution to a temperature required for boiling at 60 ° C. to a time required to develop the desired texture. Is reduced. The alkali-reduced fabric is then neutralized, and then dyed and finished to be a product.

[0028]

Next, the present invention will be specifically described based on examples. The measurement and evaluation of various characteristics in the examples were performed by the following methods. (1) Melting point (° C.) Using a differential scanning calorimeter DSC-2 manufactured by Perkin Elmer, about 5 mg of a polymer sample, in nitrogen, at a heating rate of 10 ° C. /
At 200 ° C. for 5 minutes, the temperature is lowered to 20 ° C. at a rate of 10 ° C./min, and again at a rate of 10 ° C./min.
The maximum melting exothermic peak temperature when the temperature was raised to ° C. was defined as the melting point (hereinafter referred to as Tm). (2) Glass transition temperature (° C.) The initial exothermic peak temperature obtained when measuring the above melting point was defined as the glass transition temperature. (Hereinafter referred to as Tg.) (3) MFR (g / 10 min) This is a value measured at 210 ° C. and 2160 g load according to ASTM D1238. (4) Strength and elongation of long fiber According to JIS L-1013, the maximum tensile strength at the time of pulling at a gripping interval of 30 cm and a pulling speed of 30 cm / min divided by the fineness is defined as strength. The elongation was determined from the elongation at that time. (5) Biodegradability After making the fiber into a fabric, it is poured into an aqueous solution of sodium hydroxide 10 g / l or 40 g / l at 80 ° C., and subjected to alkali reduction treatment for a predetermined treatment time while stirring.
Next, the residual liquid from which the cloth has been taken out is cooled, neutralized with hydrochloric acid, and a substance such as a low-molecular-weight polymer liberated is scooped with a wire mesh # 240 mesh. It is buried inside and removed two years later. Then, it was examined whether or not a substance such as a released low-molecular-weight polymer was present while maintaining its form, and when it did not exist, it was evaluated that the decomposability was good.

EXAMPLE 1 PET having an intrinsic viscosity of 0.7 and a melting point (Tm) of 256 ° C. was melted at 285 ° C. as a core component, and had an optical purity of 99% and an MF of 99%.
R = 4 g / 10 min, melting point (Tm) 170 ° C.
A lactic acid resin was melted at 260 ° C. as a sheath component polymer, and melt spinning was performed at a composite spinning temperature of 285 ° C. That is, using a composite spinning machine having two single-screw extruder-type melt extruders, a discharge amount of 29 g / m from a trilobe-shaped core-sheath composite nozzle having an equivalent hole diameter of 0.4 mm and 18 × 2 holes is used.
Spinning in minutes (composite ratio A / B = 50/50) (weight ratio),
While cooling and oiling with an air cooling device, the film was wound into two packages at a spinning speed of 1100 m / min to obtain an undrawn fiber.

Next, using the two undrawn fibers, drawing was performed using a multi-stage hot drawing machine capable of performing general heat drawing. That is, the ratio of the first-stage stretching ratio to the second-stage stretching ratio was 4: 1, the first roller temperature was 75 ° C., the second roller temperature was 90 ° C., the third roll temperature was not heated, and the second roller A contact type heater at 120 ° C. is provided between the first roller and the third roller. One fiber is brought into contact with the other fiber, and the other fiber is not brought into contact with the fiber.
d / 36f long fiber was obtained. The obtained long fibers had no adhesion and had a strength of 4.5 g / d and an elongation of 35%.

After warping this fiber with a single type warping machine, using a water jet loom machine, 108 warps / 2.54 c
After weaving with a plain weave structure at a weave density of 92 m and a weave of 92 / 2.54 cm, the resulting fabric was subjected to an alkali treatment. The alkali treatment was performed under the conditions of a sodium hydroxide concentration of 10 g / liter, a temperature of 80 ° C., and a treatment time of 10 minutes. The woven fabric was taken out, neutralized, washed with water and dried, and the weight loss rate was measured. The weight loss rate was 22%, and the weight loss rate of the sheath polymer was 44%.

The resulting woven fabric after the weight loss treatment had an increased drape property, had a resilient feeling, had a plump texture, and had a silky sound. The weft of the woven fabric was unwound and the strength of the fiber was measured to be 4.4 g / d. In addition, when the biodegradability of a substance released by neutralization from the waste liquid after the alkali treatment was evaluated, good degradability was shown.

Examples 2-3 The composite ratio of the core component and the sheath component was 20/80 (Example 2) and 8
Except for changing to 0/20 (Example 3) (changing the discharge amount ratio of each component), the yarn was formed in the same manner as in Example 1,
An alkali treatment was performed. None of the fibers obtained had close contact, and the fibers of Examples 2 and 3 had strengths of 4.0 g / d and 4.7 g / d, respectively, and elongations of 32% and 3%, respectively.
6%. When the weight loss rate was measured,
3% and 20%, the weight loss rate of the polymer of the sheath component is 29%
And 100%.

The texture of the woven fabric after the weight loss treatment was good in all cases, but the fabric of Example 2 had a more drape property and had a plump texture in the sense of repulsion. It was a silk noise. When the weft of this woven fabric is unwound and the strength of the fiber is measured, it is 3.9 g / d and 4.9 g / d, and the former has a sheath component remaining,
In the latter, the sheath component was almost eluted, and the polyester component having a low alkali dissolution rate was mainly composed of fibers, and the strength was not reduced at all.

Example 4 Using the woven fabric of the polyester composite fiber obtained in Example 1,
Evaluation was performed in the same manner as in Example 1 except that the treatment time of the alkali treatment was changed to 21 minutes. It is 50% when we measure weight loss rate
And the weight loss rate of the polymer of the sheath component was equivalent to 100%.

The obtained woven fabric after the weight reduction treatment had a drape property, a plump texture in a sense of rebound, and a silky sound. When the weft of the woven fabric is unwound and the strength of the fiber is measured, it is 4.8 g / d, the sheath component is completely eluted, and the polyester component having a low alkali dissolution rate becomes the main fiber, and the strength does not decrease at all. On the contrary, it was increasing. When the biodegradability of the substance released by the neutralization treatment from the waste liquid after the alkali treatment was evaluated, good degradability was shown.

Example 5 Using the polyester-based composite fiber fabric obtained in Example 3,
Evaluation was performed in the same manner as in Example 3 except that the treatment time of the alkali treatment was changed to 21 minutes. It is 21% when we measure weight loss
The weight loss of the polymer of the sheath component was 100%, and the weight of the core component was also somewhat reduced.

The obtained woven fabric after the weight reduction treatment had a drape property, had a plump texture in a repellent feeling, and had a silky sound. The weft of the woven fabric was unwound and the strength of the fiber was measured, which was 4.8 g / d. The sheath component was completely eluted, and the core component was a polyester-based fiber, and the strength was not reduced at all. From the waste liquid after the alkali treatment, the biodegradability of the substance released by the neutralization treatment was evaluated.

Example 6 Melting was performed at 240 ° C. using PET obtained by copolymerizing isophthalic acid having an intrinsic viscosity of 0.65 and a melting point (Tm) of 215 ° C. with an optical purity of 99.5% and an MFR of 10 g. / 10 min, and melted at 210 ° C. using a poly L-lactic acid resin having a melting point (Tm) of 175 ° C. as a sheath polymer, and a composite spinning temperature of 240 ° C.
Was used for melt spinning. That is, using a composite spinning machine having two single-screw extruder-type melt extruders, a discharge rate of 27 g / min from a trilobe-shaped core-sheath composite nozzle having an equivalent hole diameter of 0.4 mm and 18 × 2 holes is used. (Composite ratio A / B =
50/50) (weight ratio), the mixture was cooled by an air cooling device and wound into two packages at a spinning speed of 1100 m / min while being oiled to obtain an undrawn fiber.

Using these two undrawn fibers, drawing was performed using a general multi-stage hot drawing machine capable of hot drawing. That is, the ratio of the first-stage stretching ratio to the second-stage stretching ratio is 4:
1. The first roller temperature is 75 ° C, the second roller temperature is 90 ° C
The third roll temperature is not heated, and a contact type heater of 120 ° C. is installed between the second roller and the third roller. One fiber is brought into contact with this heater, and the other fiber is brought into contact without drawing. After stretching at a magnification of 3.0 times, the yarns were combined and 7
5d / 36f long fiber was obtained. The obtained long fiber had no adhesion and had a strength of 3.8 g / d and an elongation of 37%.

Using this filament, a woven fabric was prepared in the same manner as in Example 1 and evaluated. First, when the weight loss rate is measured, 2
It was 3%, and the weight loss rate of the polymer of the sheath component was equivalent to 46%. The woven fabric after the weight loss treatment had a drape property higher than that of the woven fabric of Example 1, had a resilient feeling, had a plump texture, and had a silky sound. The weft of the woven fabric is unwound and the fiber strength is measured to be 3.7 g /
d, and the fiber strength was not significantly reduced. From the waste liquid after the alkali treatment, the biodegradability of the substance released by the neutralization treatment was evaluated.

EXAMPLE 7 PET containing copolymerized isophthalic acid having an intrinsic viscosity of 0.65 and a melting point (Tm) of 205 ° C. was melted at 230 ° C. as an A component, and had an optical purity of 90% and an MFR of 18 g / 10 Min, and a poly-L-lactic acid resin having no melting point (Tm) peak was melted at 210 ° C. as a polymer of the B component, and the composite spinning temperature was 23 ° C.
Melt spinning was performed at 0 ° C. That is, using a composite spinning machine having two single-screw extruder-type melt extruders, a discharge rate of 37 g / min (composition ratio A / B = 50 /
50) Spinning (weight ratio), winding at a spinning speed of 4500 m / min while cooling and oiling with an air cooling device to obtain a 75d / 36f long fiber having a cross section as shown in FIG. 1 (g). Was. The obtained long fibers have no adhesion and have a strength of 3.
9 g / d and elongation 53%.

A woven fabric was formed using this long fiber in the same manner as in Example 1 and evaluated. First, when the weight loss rate was measured, it was 20%, and the weight loss rate of the polymer of the B component was equivalent to 40%. Examination of the fiber cross section of the woven fabric revealed that the woven fabric had a sharp edge as if it were gear-shaped. The obtained woven fabric after the weight loss treatment was different from those of Examples 1 to 6, and had a feeling of repulsion and a dry touch texture. The weft of the woven fabric was unwound and the fiber strength was measured to be 3.8 g / d, and the fiber strength was not significantly reduced. From waste liquid after alkali treatment,
When the biodegradability of the substance released after the neutralization treatment was evaluated, good degradability was shown.

Comparative Example 1 Spinning was carried out in the same manner as in Example 1 except that the sheath component was the same polymer as the core component, the melting temperature was used, and the discharge rate was 33 g / min. Except that the stretching was performed under the same conditions as in Example 1, a long fiber of 75d / 36 was obtained.
The obtained long fiber had no adhesion, and had a strength of 4.9 g / d and an elongation of 40%.

Using this filament, a woven fabric was prepared in the same manner as in Example 1, and then evaluated. It is 1% when we measure weight loss rate
, And there was almost no weight loss. This was 22 times slower than the dissolution rate ratio in Example 1.
The woven fabric after the weight loss treatment has little drape and repulsion,
It had a slightly swelling texture but did not squeal.

Next, when the concentration of the alkali treatment was set to 40 g / L, which is four times that of Example 1, and the treatment was carried out for 74 minutes, a weight loss rate of 22% was obtained for the first time. The resulting woven fabric after weight loss treatment is
It had less drapability than that of Example 1 and had a slightly swelling texture in a slightly repulsive feeling, resulting in little silk noise effect. Unravel the weft of this fabric,
When the strength of the fiber was measured, it was 4.7 g / d, and the fiber strength did not decrease much. From the waste liquid after the alkali treatment, the biodegradability of the substance released by the neutralization treatment was evaluated.

[0047]

According to the present invention, there is provided a multifunctional polyester-based composite fiber which is biodegradable, does not pollute the environment, has relatively high fiber strength, and can impart bulkiness and drape. . In particular, since the polymer exposed on the surface of the fiber is biodegradable and uses components that can be easily reduced in weight, it can be used in an environment-friendly manner including waste liquid treatment, and can be used for knitting, woven fabric, non-woven fabric and other various fibers. When applied to structures, composite structures, etc., soft and bulky products can be obtained by weight reduction treatment, and can be suitably used for clothing, household goods, and the like. Furthermore, the recovered substances contained in the waste liquid of the weight loss treatment are beneficial from the viewpoint of protecting the natural environment because, when left in an environment where a large number of microorganisms are present, for example, in soil or water, they are eventually completely decomposed and lost. Alternatively, it can be reused, for example, by composting it into fertilizer, which is advantageous from the viewpoint of resource reuse.

[Brief description of the drawings]

1 (a) to 1 (k) are schematic views showing cross sections of a polyester-based composite fiber of the present invention before a weight reduction treatment.

Claims (2)

[Claims] 1. A conjugate fiber mainly composed of two kinds of polyester polymers A and B having different dissolution rates, wherein the polyester polymer B having a high dissolution rate is an aliphatic polyester and at least a fiber. A polyester-based composite fiber, which is arranged so as to be exposed on a part of the surface and is reduced in weight by 10 to 100%. 2. The aliphatic polyester is a polylactic acid-based polymer, wherein poly (D-lactic acid), poly (L-lactic acid),
-Selected from the group consisting of a polymer of an optical isomer by lactic acid and L-lactic acid or a blend thereof, a copolymer of D-lactic acid and hydroxycarboxylic acid, and a copolymer of L-lactic acid and hydroxycarboxylic acid. The polyester composite fiber according to claim 1, which is a polymer or a blend thereof.