JP2006328628A - Thermally splittable conjugate fiber and fiber aggregate thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermally splittable fiber that can readily be split highly and instantaneously only by thermal treatment to manifest ultrafine fiber and further provide a nonwoven fabric having excellent thermal processability (thermal processing speed and process passing passing property) and high specific volume. <P>SOLUTION: In this thermally splittable conjugate fiber, a thermoplastic resin having a melting point T<SB>1</SB>(°C) and thermal shrinkage at a temperature T<SB>1</SB>-13≤T<T<SB>1</SB>of more than 40% is used as the first component (1) while another thermoplastic resin having a melting point T<SB>2</SB>satisfying 150≤T<SB>2</SB><300 and substantially causing no thermal shrinkage at a temperature T is used as the second component (2), and a hydrophilizing agent is added to the first component in an amount of 0.1 to 5.0 mass%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  It is related to split-type composite fibers that can be easily and instantly divided by heat treatment and has excellent thermal processability (thermal processing speed, processability), and in fields that require hydrophilic performance such as sanitary materials, wipers, and filters. And a non-woven fabric using the same.

Conventionally, in order to obtain excellent flexibility, tactile sensation, wiping property, and the like, a nonwoven fabric obtained by dividing a split-type composite fiber to express ultrafine fibers has been used. As a split type composite fiber to be split by physical impact of high-pressure fluid flow processing or needle punch processing, for example, JP-A-8-311717 discloses fatty acid glyceride (monoglycerin fatty acid ester) as at least one component of polyolefin resin. In addition, there is disclosed a polyolefin-based split type composite fiber in which a hydrophilic component selected from an alkoxylated alkylphenol and a polyoxyalkylene fatty acid ester is kneaded and added. The present applicant also proposes a polyolefin-based split composite fiber composed of a combination of polyolefin resins having a Rockwell hardness of 60 or more and a carbon number difference of each component Δn> 0.9 in Japanese Patent Publication No. 6-63129. Yes. Further, as a heat splitting composite fiber that is split using a difference in heat shrinkage rate between two components, for example, JP-A-2-169720 and JP-A-4-316608 disclose a polyolefin having a high heat shrinkage rate. There is disclosed a heat splitting composite fiber in which a system component and a polyolefin system component are incompatible components.
JP-A-8-311717 Japanese Examined Patent Publication No. 6-63129 JP-A-2-169720 JP-A-4-316608 JP-A-9-49160 JP-A-9-31755

However, the split composite fibers have the following problems. In Japanese Patent Application Laid-Open No. 8-31717 and Japanese Patent Publication No. 6-63129, both attempts were made to divide highly by the physical impact of high-pressure fluid flow processing or needle punch processing, and the number of production steps was reduced. Not only is the production speed slow, requires a lot of energy, and the cost is high, but the nonwoven fabric obtained by physical impact can only obtain a high density entangled nonwoven fabric with a specific volume of 5 cm ³ / g or less. Therefore, its use is limited at present. On the other hand, in JP-A-2-169720 and JP-A-4-316608, a non-woven fabric having a large specific volume can be obtained because it is divided not by physical impact but by thermal contraction. Dividing performance is insufficient only by providing a rate difference. In Japanese Patent Laid-Open No. 9-49160, after air-through treatment with heated air, mechanical entanglement processing is performed to improve dividing performance. In Japanese Patent No. 9-31755, a thermal partitioning composite fiber obtained by adding a petroleum resin to a low melting point component having a large thermal shrinkage rate is subjected to thermal means, and then immersed in a petroleum resin-soluble solvent (solvent treatment), followed by press treatment. To improve the splitting performance. For this reason, not only the number of production processes is increased and the cost is increased, but also only a high density nonwoven fabric can be obtained.
Therefore, the actual situation is that a split-type composite fiber that can be highly divided without using physical impact has not yet been obtained.

  The present invention has been made in view of such a situation. That is, the two components are divided by heat, which is composed of two different components, the heat-shrinkable thermoplastic resin as the first component, and the other as the second component. A possible heat-splitting composite fiber, wherein the first component of the two components contains 0.1 to 5 mass% of a hydrophilizing agent. By adopting such a configuration, even with heat treatment alone, it is possible to divide highly and instantly to express ultrafine fibers, and to obtain a nonwoven fabric with excellent thermal processability (thermal processing speed, processability) and a large specific volume. Can do. At the same time, the heat-splitting composite fiber of the present invention and the non-woven fabric using the same have high and permanent hydrophilicity, and therefore can be used in fields that require hydrophilic performance such as sanitary materials, wipers, and filters. .

In the present invention, the composite fiber has a melting point of T ₁ (° C.), a thermoplastic resin having a heat shrinkage of 40% or more at a temperature T ₁ −13 ≦ T <T ₁ as a first component, and a melting point of It is desirable that the fiber is a heat-splitting composite fiber composed of two components, the second component being a thermoplastic resin that is in the range of 150 ≦ T ₂ <300 and has substantially no thermal shrinkage at temperature T. The first component thermoplastic resin is at least one selected from an ethylene-propylene copolymer and an ethylene-propylene-butene-1 terpolymer having a melting point of 130 ≦ T ₁ ≦ 145. It is desirable to contain 0.1-5 mass% of a hydrophilizing agent.

  In addition, the hydrophilizing agent used in the present invention is an ester compound of a polyglycerin having a polymerization degree (n) of 2 to 10 and a saturated or unsaturated fatty acid having 8 to 22 carbon atoms (R is a saturated or unsaturated hydrocarbon). Polyglycerin fatty acid ester) is desirable.

  And the fiber assembly formed by heat-treating the fiber web containing 20 mass% or more of the heat splitting composite fiber of the present invention is highly divided to express ultrafine fibers and can be used for various applications. .

The heat-splitting conjugate fiber of the present invention has a heat shrinkage rate of 40% or more of two components of a thermoplastic resin having a heat shrinkage rate of 40% or more and a thermoplastic resin having substantially no heat shrinkage. By including a hydrophilizing agent in the plastic resin, it is possible to divide the fiber finely and instantaneously only by heat treatment to express ultrafine fibers and obtain a nonwoven fabric with a large specific volume. At the same time, the heat splitting composite fiber and the fiber assembly of the present invention can have a high degree of permanent hydrophilicity. Furthermore, the first component thermoplastic resin is at least one selected from an ethylene-propylene copolymer and an ethylene-propylene-butene-1 terpolymer having a melting point of 130 ≦ T ₁ ≦ 145, When a hydrophilizing agent is included, a high degree of thermal shrinkage can be obtained, and not only excellent instantaneous partitionability, but also excellent thermal processing temperature, thermal processing speed and processability, and low cost thermal partition type composite fiber and fiber assembly. You can get things. Further, as a hydrophilizing agent, when a polyglycerin fatty acid ester composed of polyglycerin having a polymerization degree (n) of 2 to 10 and a saturated or unsaturated fatty acid having 8 to 22 carbon atoms (R is saturated or unsaturated hydrocarbon) is used, Higher resolution and hydrophilicity can be obtained. The fiber assembly using the heat-splitting composite fiber of the present invention can be suitably used in fields that require hydrophilic performance such as sanitary materials, wipers, and filters.

The contents of the present invention will be specifically described below.
The heat splitting composite fiber of the present invention is composed of two different components, and a heat splitting composite capable of splitting two components by heat using a heat-shrinkable thermoplastic resin as the first component and the other as the second component. Fiber. The component having heat shrinkability in the present invention refers to a component having a larger heat shrinking force when one component and the other component are treated under the same heat treatment conditions. In the heat-splitting conjugate fiber of the present invention, at least one component of the plurality of components in the fiber cross section is divided into two or more, and each component is a structural unit of the fiber cross section, and each structural unit is Each structural unit is adjacent to structural units of different components, and a part of each structural unit is exposed on the fiber surface, and the shape may be any of circular, irregular, and hollow. For example, FIG. And it has a fiber form as shown in FIG. The heat-splitting composite fiber of the present invention includes a thermoplastic resin having a melting point of T ₁ (° C.) and a thermal shrinkage of 40% or more at a temperature T ₁ −13 ≦ T (° C.) <T ₁ . A two-component thermoplastic resin having a melting point of 20 ° C. or more higher than T ₁ and 150 ≦ T ₂ (° C.) <300, and having substantially no thermal shrinkage at temperature T. Preferably it consists of. The melting point as used in the field of this invention means what was measured by DSC method according to JIS-K-7122. The heat shrinkage at temperature T ₁ −13 ≦ T <T ₁ in the present invention means that the first component and the second component are melt-spun in the temperature range of 220 to 300 ° C. as a single component, and 70 A sample was prepared by stretching it three times or more in warm water, hot air, or a heat medium at ℃ or higher, so that the final fineness was 2.2 to 11 dtex, and JIS-L-1013 7.16.2 (heat According to the shrinkage temperature), the sample length is 10 cm, the initial load is 2 mg / dtex, the sample length at a predetermined temperature is measured, and the value obtained by subtracting the sample length after shrinkage from the sample length before shrinkage (10 cm) Dividing by the sample length and multiplying by 100 was the heat shrinkage rate. In the present invention, the thermal contraction rate of the first component at the temperature T is 40% or more, more preferably 50% or more. This is because if the heat shrinkage rate of the first component is less than 40%, shrinkage peeling from the second component is insufficient, and the fiber becomes difficult to be divided during processing of a nonwoven fabric or the like.

Examples of the thermoplastic resin that satisfies the above range include propylene-based copolymers such as ethylene-propylene copolymer (hereinafter referred to as EP) or ethylene-propylene-butene-1 terpolymer (hereinafter referred to as EPB), Examples thereof include an ethylene-butene-1 copolymer (hereinafter referred to as EB), an isophthalic acid component or a polyester copolymer containing a metallized sulfonic acid group. Among these, at least one selected from EP, EPB, and EB having a melting point in the range of 120 ≦ T ₁ ≦ 145 is preferable in terms of workability and cost. Examples of the EP and EPB include a propylene random copolymer or a block copolymer having an ethylene content of 2 to 8 mass%. In terms of the heat shrinkage rate, EP is the most excellent, followed by EPB and EB in this order, and the use of EP is most preferable in terms of thermal partitioning.

On the other hand, the second component is a thermoplastic resin having a melting point higher than T ₁ by 20 ° C. or more, 150 ≦ T ₂ (° C.) <300, and having substantially no thermal shrinkage at the temperature T. The difference in melting point from one component is preferably 50 ° C. or more. If the difference in melting point is less than 20 ° C., it is difficult to control the temperature of the heat processing machine, or in hot air processing, etc., adhesion may occur near the softening temperature depending on the air volume, and the processing temperature may be restricted, This is because heat shrinkage of one component is inhibited. Further, the term “substantially free of heat shrinkage” as used herein means that the heat shrinkage rate at temperature T is less than 4%, preferably less than 1%. This is because heat shrinkage at temperature T is not only inferior in heat partitionability but also causes great heat shrinkage when it is made into a nonwoven fabric, resulting in textured spots. Examples of the thermoplastic resin that satisfies the above conditions include polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins such as nylon 6, nylon 66, nylon 610, nylon 11, and nylon 12, polymethylpentene, polypropylene, and ethylene vinyl alcohol. Polyolefin resins such as copolymers can be used. Among them, the heat-splitting composite fiber of the present invention, when polyester, polyamide, or polymethylpentene is used as the second component, is a viewpoint of process stability and heat-splitting property in fiber production with the first component EP or EPB. Is preferable.

  And in this invention, in order to improve the instantaneous partition property only by heat processing, a hydrophilizing agent is made to contain 0.1-5 mass% in any one of said 2 components. A more preferable content rate is 0.3 to 3 mass%. By including a hydrophilizing agent, not only the splitting property but also high and permanent hydrophilic performance can be obtained at the same time. When the content of the hydrophilizing agent is less than 0.1 mass%, the splitting property is insufficient and hydrophilic performance cannot be obtained. When the content exceeds 5 mass%, yarn breakage during spinning increases. This is not preferable because it causes deterioration of quality and processability. In addition, it is particularly preferable to add a hydrophilizing agent to the first component, which is a heat-shrinkable component, of the two components, because the releasability between the components accompanying shrinkage is improved and the splitting property is excellent.

  The hydrophilic agent may be any compound having a hydrophilic group such as a hydroxyl group, a carbonyl group, a carboxyl group, or a sulfone group. For example, fatty acid glyceride (monoglycerin fatty acid ester), alkoxylated alkylphenol, Oxyalkylene fatty acid esters, fatty acid diethanolamides and the like can be mentioned, but those having as long a hydrophilic performance as possible (hydrophilic persistence) or those having a slow bleed speed to the fiber surface (hydrophilic slow-acting property) are preferable, for example, satisfying both As an example, an ester compound of a polyglycerin having a polymerization degree (n) of 2 to 10 and a saturated or unsaturated fatty acid having 8 to 22 carbon atoms (R is saturated or unsaturated hydrocarbon) represented by the following formula (Chemical Formula 2) (Hereinafter also referred to as “polyglycerin fatty acid ester”) Performance not only excellent split resistance, particularly preferred.

  Next, the manufacturing method of the heat | fever division type composite fiber of this invention is demonstrated. First, a thermoplastic resin satisfying the above range is prepared, and one of the two components, preferably the first component, contains the hydrophilizing agent. As a method of inclusion, a method of supplying a hydrophilizing agent to the extruder at a predetermined ratio together with the constituent resin pellets at the time of melt spinning, mixing using a known mixing device, and using a known single-screw or twin-screw extruder, etc. Although the method of melt-mixing and making a masterbatch beforehand is mentioned, the latter is preferable because the hydrophilizing agent is uniformly dispersed in the components.

  The two components are known melt spinning machines using a split type composite nozzle, and the spinning temperature is set so that the first component and the second component are adjacent to each other and divided from each other in the fiber cross section. The resin is extruded at 220 to 300 ° C. and melt-spun to produce a spinning filament having a fineness of 5 to 50 dtex. At this time, the composite ratio (volume ratio) of the two components is preferably 80:20 to 20:80 in consideration of spinnability and splitting property. The spun filament is then drawn as needed. Stretching is preferably performed in warm water, hot air, or a heat medium at a stretching temperature of 70 ° C. or higher, and in the case of using EP or EPB at 70 to 130 ° C., and at a stretching ratio of 3 times or higher, the fiber strength is improved. In addition, the closer the draw ratio is to the breaking point, the greater the heat shrinkage rate of the first component, particularly EP or EPB. On the other hand, if the second component is a general-purpose resin such as polyethylene terephthalate, the heat shrinkage rate approaches 0 and the moment. Dividability is improved, which is preferable. A fiber treating agent may be adhered to the obtained drawn filament. And if necessary, it is crimped by a crimping device and cut into a predetermined length to obtain the heat splitting composite fiber of the present invention.

  The fineness of the obtained heat-splitting composite fiber may be appropriately set so that the fineness of the ultrafine fiber after splitting is less than 1 dtex, but is preferably 0.5 to 20 dtex. This is because if the fineness of the composite fiber is less than 0.5 dtex, fiberization becomes difficult, and if it exceeds 20 dtex, it becomes difficult to obtain ultrafine fibers having a fineness of less than 1 dtex after division. Moreover, it is preferable that the fineness of the ultrafine fibers generated after the division is less than 1 dtex. More preferably, it is less than 0.5 dtex, and still more preferably less than 0.3 dtex. In addition, the fiber form may be any shape of end staple fibers or papermaking short fibers, or long fibers such as multifilaments. This is preferable in that the second component shrinks and fiber division is easily promoted.

  The obtained heat-splitting composite fiber can be processed into a fiber assembly such as a nonwoven fabric, felt, paper, woven fabric, knitted fabric, and flocked product. At this time, the content of the heat splitting composite fiber is preferably 20 mass% or more. More preferably, it is 30 mass%. This is because if the content is less than 20 mass%, the fine texture and functionality unique to ultrafine fibers cannot be exhibited. Other materials to be mixed in addition to the heat splitting composite fiber of the present invention are not particularly limited, but cellulose fibers such as cotton, pulp, hemp, rayon, polyester fibers such as polyethylene terephthalate and polybutylene terephthalate, nylon 6. One or two or more can be arbitrarily selected from polyamide fibers such as nylon 66, acrylic fibers, or polyolefin fibers. Also, the fiber shape is not particularly limited, and the cross section of a single fiber, a sheath-core composite fiber, an eccentric sheath-core composite fiber, a parallel composite fiber, a sea-island composite fiber, a split composite fiber, etc. is circular, irregularly shaped Any of these may be used.

  As the form of the fiber aggregate, a nonwoven fabric form is particularly useful. Nonwoven fabrics include thermal bond nonwoven fabrics, chemical bond nonwoven fabrics, spunlace nonwoven fabrics, nonwoven fabrics mainly composed of staple fibers such as needle punched nonwoven fabrics, nonwoven fabrics composed of long fibers such as spunbond nonwoven fabrics, wet nonwoven fabrics produced by wet papermaking, and airlaid nonwoven fabrics. It is preferable to determine the nonwoven fabric made of short fibers such as these, or a laminate of these according to the purpose and application, and among them, the thermal bond nonwoven fabric made of an air-through nonwoven fabric or an embossed nonwoven fabric exhibits the heat splitting property of the present invention. This is the most effective form above.

The thermal bond nonwoven fabric may be manufactured as follows. The heat treatment is preferably performed at a temperature at which the thermal shrinkage rate of one component is 40% or higher, that is, T (° C.) or higher, and further at a temperature higher than the melting point of the first component, that is, T ₁ (° C.) or higher. Then, it is more preferable in that it is highly heat-shrinkable and the splitting property is improved, and the constituent fibers can be heat-sealed. Also the heat treatment temperature is less than T _1, for example, high density polyethylene / polypropylene, high density polyethylene / polyester, low density polyethylene / polypropylene, ethylene - low-melting first component is from T ₁ of the vinyl acetate copolymer / polypropylene A composite fiber made of the above may be contained and heat-sealed.

  Hereinafter, the present invention will be described in more detail with reference to examples. The fiber strength, the nonwoven fabric thickness, the split ratio, and the hydrophilicity were measured as follows.

[Fiber strength]
It measured according to JIS-L-1015.

[Thickness]
Using a thickness measuring machine (trade name: THICKNESS GAUGE model CR-60A manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), measurement was performed with a load of 20 g per 1 cm ^{2 of} the sample.

[Split rate]
The observed portion of the nonwoven fabric was magnified 500 times with an electron microscope and arbitrarily photographed at three locations, and the division ratio was calculated by the area ratio of the divided portion of the photograph.

[Hydrophilic]
The test was conducted according to the liquid permeation test method described in JP-A-9-322911. That is, “Toyo No. 2 filter paper” manufactured by Advantech Toyo Co., Ltd. is stacked on a non-woven fabric cut to a size of 60 mm × 60 mm, and a pair of glass instruments for liquid passage (high height) are formed through silicon packing. And a cylindrical shape having a thickness of 75 mm, an inner diameter of 36 mm, and a thickness of 3 mm. And the flange part with an outer diameter of 60 mm was provided in the both ends of the glass apparatus for liquid flow, and the electronic balance by which the liquid receiver was mounted was arrange | positioned under the glass apparatus for liquid flow of the lower part. Next, 40 ml of ion exchange water is injected into the upper glass apparatus for liquid flow, and the time until the liquid flow volume reaches 20 ml is measured. After passing 20 ml, the nonwoven fabric is taken out and sandwiched between two filter papers. A weight of 1 kg is placed on the non-woven fabric and left for 1 minute. The cycle (1 time), the 3rd cycle (3 times), and the 5th cycle (5 times) were performed. In addition, the evaluation of the liquid passing time exceeding 180 seconds was x.

[Example 1]
The first component has a melting point of 138 ° C., an ethylene content of 4 mass%, and an ethylene-propylene copolymer (EP, manufactured by Ube Industries, Ltd .: trade name Y-2045GP) having a heat shrinkage of 50% at 125 ° C. 10 mass% of a master batch containing 8 mass% of a polyglycerin fatty acid ester composed of polyglycerin having a polymerization degree of 4 and an unsaturated fatty acid having 6 carbon atoms is used as a solubilizing agent. The second component is polyethylene terephthalate (PET, manufactured by Toray Industries, Inc .: trade name T-200E) having a heat shrinkage of 0% at a melting point of 265 ° C. and 138 ° C., using an eight-part nozzle. 8-split composite with melt ratio of 50/50, spinning temperature of 240 ° C / 300 ° C, take-up speed of 1000m / min and gear size of 6.7dtex. To give the yarn filaments. Next, the spinning filament is wet-stretched three times in warm water at 80 ° C., 0.3 mass% of the hydrophilic oil agent is adhered, mechanical crimping is imparted through a stuffer box, and a conveyor-type hot air penetration type at 110 ° C. Drying was performed with a dryer and cut to obtain a heat-splitting composite fiber having a fineness of 2.2 dtex and a fiber length of 38 mm. The thermal shrinkage ratios of EP and PET are each a single component, and the above spinning temperature (EP is 240 ° C., PET is 300 ° C.), take-up speed (1000 m / min), stretching conditions (3 times in 80 ° C. warm water) A single fiber (fineness: 2.2 dtex) obtained by treatment in the drawing was evaluated.

A card web having a basis weight of 30 g / m ² is produced from the obtained fiber with a roller card, and an embossing roll having an embossing area of 0.785 mm ² / piece and an embossing ratio of 19.6% is used. Embossing was performed at 4 m / min and a linear pressure of 30 kg / cm to obtain an ultrafine fiber nonwoven fabric.

[Example 2]
A master batch containing 90 mass% of the ethylene-propylene copolymer of Example 1 and 8 mass% of a polyglycerin fatty acid ester composed of polyglycerin having a polymerization degree of 4 and oleic acid (unsaturated fatty acid having 17 carbon atoms) as a hydrophilizing agent. A heat-splitting composite fiber and an ultrafine fiber nonwoven fabric having a fineness of 2.2 dtex and a fiber length of 38 mm were produced in the same manner as in Example 1 except that 10 mass% of the mixed thermoplastic resin (hydrophilic agent content 0.8 mass%) was used. Obtained.

[Example 3]
A thermoplastic resin (hydrophilizing agent content 1.6 mass%) in which 80 mass% of the ethylene-propylene copolymer of Example 1 was mixed with 20 mass% of a master batch containing 8 mass% of the polyglycerol fatty acid ester of Example 2 was used. Except for the above, heat-splitting composite fibers and ultrafine fiber nonwoven fabrics having a fineness of 2.2 dtex and a fiber length of 38 mm were obtained in the same manner as in Example 1.

[Example 4]
As the hydrophilizing agent, a fine glycerin fatty acid ester having a fineness of 2.2 dtex and a fiber length of 38 mm was used in the same manner as in Example 1 except that R represented by the following formula (Chemical Formula 3) was a monoglycerin fatty acid ester having an alkyl group having 17 carbon atoms. Thermally divided composite fibers and ultrafine fiber nonwoven fabrics were obtained.

[Comparative Example 1]
A heat-splitting conjugate fiber and a nonwoven fabric were obtained in the same manner as in Example 1 except that the hydrophilizing agent was not added to the first component.

[Comparative Example 2]
The nonwoven fabric of Comparative Example 1 is sprayed with a high-pressure columnar water flow twice from the front and back surfaces at a pressure of 6 MPa to divide the heat splitting composite fiber and entangle the fibers, and dry at 110 ° C. to form the entangled nonwoven fabric. Obtained.

[Comparative Example 3]
A thermoplastic resin (hydrophilizing agent content: 0.08 mass%) was prepared by mixing 1 mass% of the master batch containing 8 mass% of the polyglycerin fatty acid ester of Example 2 with 99 mass% of the ethylene-propylene copolymer of Example 1. Except for the above, heat-splitting conjugate fibers and nonwoven fabrics were obtained in the same manner as in Example 1.
The physical properties of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 1.

  The heat splitting composite fibers of Examples 1 to 4 are split by 50% or more only by heat treatment with an embossing roll. In particular, when the polyglycerin fatty acid ester shown in Chemical Formula 2 is used as a hydrophilizing agent, it is highly split. Excellent durability and hydrophilicity. On the other hand, Comparative Example 1 is not sufficiently divided only by heat treatment, and in order to divide most of the fibers, the high-pressure columnar flow treatment of Comparative Example 2 must be used in combination, and a high-density nonwoven fabric with a small specific volume. Only obtained. Moreover, since the hydrophilizing agent was not provided, durable hydrophilic property was not obtained. In Comparative Example 3, since the content of the hydrophilizing agent was small, the splitting property was not sufficient.

  The fiber assembly using the heat-splitting composite fiber of the present invention can be suitably used in fields that require hydrophilic performance, such as sanitary materials, wipers, and filters.

An example of fiber sectional drawing of the split type composite fiber used for this invention is shown. Another example of the fiber sectional view of the split type composite fiber used in the present invention is shown.

Explanation of symbols

1. First component Second ingredient

Claims (5)

  A heat-splitting type composite fiber that can be split into two components by heat, which is composed of two different components and has a heat-shrinkable thermoplastic resin as the first component and the other as the second component, The first component contains a hydrophilizing agent in an amount of 0.1 to 5 mass%. The composite fiber has a melting point T ₁ (° C.), a thermoplastic resin having a heat shrinkage rate of 40% or more at a temperature T ₁ −13 ≦ T (° C.) <T ₁ as a first component, and a melting point of T ₁ 2. It is composed of two components, which are higher than 20 ° C. and in the range of 150 ≦ T ₂ (° C.) <300, and the second component is a thermoplastic resin having substantially no thermal shrinkage at temperature T. The heat splitting composite fiber according to 1. The first component thermoplastic resin is an ethylene-propylene copolymer, an ethylene-propylene-butene-1 terpolymer, and an ethylene-butene-1 copolymer having a melting point of 120 ≦ T ₁ ≦ 145. The heat-splitting type composite fiber according to claim 1 or 2, which is at least one selected and contains 0.1 to 5 mass% of a hydrophilizing agent. The hydrophilizing agent is an ester of a polyglycerin having a polymerization degree (n) of 2 to 10 represented by the following formula (Chemical Formula 1) and a saturated or unsaturated fatty acid having 8 to 22 carbon atoms (R is a saturated or unsaturated hydrocarbon). The heat splitting composite fiber according to claim 1 or 3, wherein the heat splitting composite fiber is a compound.

A fiber assembly comprising a fiber web containing 20 mass% or more of the heat splitting composite fiber according to any one of claims 1 to 4, which is heat-treated.

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