JP2000017554A - Opened nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonwoven fabric having excellent liquid absorbability, rich flexibility and rich air permeability, and useful for various kinds of uses. SOLUTION: This opened nonwoven fabric is obtained by applying a high pressure columnar water flow treatment to a fiber web on a support for forming openings. The fiber web comprises 70-30 wt.% of hydrophilic fibers and 30-70 wt.% of split type conjugate fibers each comprising two different resins and having a fiber cross section in which at least one of the two components is divided into two or more divisions. The obtained nonwoven fabric has many opened holes penetrated from the front surface of the non-woven fabric to the back surface, and has excellent liquid absorbability. In the non-woven fabric, the constituting fibers are substantially not thermally adhered to each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonwoven fabric which is excellent in liquid absorbability, flexible and breathable, and is suitable for sanitary materials such as gauze and bandage, wet tissue, wiping cloth and the like. .

[0002]

2. Description of the Related Art Conventionally, nonwoven fabrics used for sanitary materials are:
Various proposals have been made using a breathable sheet, or using a film or nonwoven fabric having an aperture. These are breathable to prevent jolting,
Simultaneously satisfies the liquid-absorbing property for passing bodily fluids through the absorption section. For example, Japanese Patent Application Laid-Open No. Sho 63-238861 discloses a hydrophobic sheet having a large number of holes through which a liquid can pass, and a hydrophilic rubber material applied to the surface to make the surface hydrophilic. A sheet that has been proposed. Japanese Patent Application Laid-Open No. 6-280150 proposes a perforated laminated sheet in which a hydrophobic ultrafine fiber aggregate layer and a hydrophilic fiber aggregate layer are integrated.

On the other hand, as a nonwoven fabric which simultaneously satisfies the property of capturing dust and dirt such as wet tissues and wiping cloths and the property of wiping liquids, see, for example, Japanese Patent Application Laid-Open No. 2-683.
No. 45 proposes a nonwoven wipe comprising a composite web containing at least 10% of a mixture of rayon fibers and polyester fibers, the openings being formed by liquid flow treatment. Japanese Patent Application Laid-Open No. 8-275915 discloses that a coarse layer mainly composed of a thick fiber of 1 denier or more has a thickness of 0.8%.
A wiping material having a dense layer mainly composed of ultrafine fibers of denier or less and having an opening is disclosed.

[0004]

However, these nonwoven fabrics have the following problems. For example, JP-A-63
In Japanese Patent No. 238861, the texture, flexibility, and the like are inferior to nonwoven fabrics obtained by a hydroentanglement method or the like because the skin contact surface is a sheet of a polymer film. In addition, Japanese Unexamined Patent Publication
-280150 also uses a thermoplastic spunbonded nonwoven fabric as the hydrophilic fiber aggregate layer and a meltblown nonwoven fabric as the hydrophobic microfine fiber aggregate layer, so that the fibers are melt-bonded at the entanglement point, In addition, it is not only inferior in flexibility but also cannot exert its effect on both sides of the nonwoven fabric.

Further, in Japanese Patent Application Laid-Open No. 2-68345, the rayon fiber and the polyester fiber are made of staple fiber and have a fineness of 1 denier or more, and are bonded with a resin binder. Hard and uncomfortable for the user. JP 8
In Japanese Patent No. 275915, since a rough layer and a dense layer are laminated, only one surface can be used, which is not suitable for wiping over a wide area. The present invention has been made in view of the above circumstances, and has an object to obtain a nonwoven fabric which is excellent in liquid absorbability and is useful in various applications having high flexibility.

[0006]

The perforated nonwoven fabric of the present invention comprises:
A split type composite fiber composed of two different resins and at least one component is divided into two or more in a fiber cross section, and a hydrophilic fiber, and a large number of apertures penetrating from the front surface to the back surface of the nonwoven fabric were formed. In non-woven fabric,
The constituent fibers are not substantially bonded to each other,
The water absorption at 1018 (Method B) is 10 mm or more;
And the rigidity (Method A) in JIS L 1096 is 6
It is characterized by being less than 0 mm. With such a configuration,
It is possible to obtain a nonwoven fabric which is excellent in liquid absorbing properties, and which is rich in flexibility and gas permeability, which has not been obtained conventionally.

In the porous nonwoven fabric of the present invention, the splittable conjugate fiber is 20 to 50% by weight, and the hydrophilic fiber is 80 to 5% by weight.
Desirably, 0% by weight is mixed. Hereinafter, the contents of the present invention will be specifically described.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The open nonwoven fabric of the present invention comprises a splittable conjugate fiber composed of two different resins and at least one component divided into two or more in a fiber cross section, and a hydrophilic fiber. Has a structure in which constituent fibers are not substantially bonded to each other. The term "substantially not bonded" as used herein means that the nonwoven fabric is maintained only by entanglement of the constituent fibers without self-adhesion of the constituent fibers or bonding by an adhesive or the like. In the splittable conjugate fiber used in the present invention, two components are made of different resins, and at least one component of a first component and a second component is divided into two or more in a fiber cross section, and each component is a fiber. It is a structural unit of a cross section, and each structural unit is adjacent to a structural unit of a different component, and each structural unit has a structure in which a part of the structural unit is exposed on the fiber surface. Specifically, for example, in a fiber cross section, FIG.
As shown in (c), those in which the constituent units are arranged in a windmill shape or a layer shape are exemplified. At this time, the number of constituent units in the fiber cross section is preferably 8 to 16. This is because if the number of constituent units is small, division may be caused during the stretching process, or the fineness of the ultrafine fiber after division may be increased. Conversely, if the number of constituent units is large, division may be difficult.

The resin used in the present invention is not particularly limited as long as the resin has two components. For example, polyester-based resin / polyolefin-based resin, polyester-based resin / polyamide-based resin, or polyolefin-based resin / polyamide-based resin may be used. Further, a homologous resin may be used. For example, when a splitting accelerator such as a silicon-based compound or an inorganic substance is mixed with at least one of the resins, the splitting becomes possible, so that it is preferably used.
Among them, polyester-based resin / polyolefin-based resin or polyester-based resin / polyamide-based resin is excellent in incompatibility, improves texture flexibility, improves surface texture, and maintains a bulky feeling. A splittable conjugate fiber composed of a combination of resins is preferred.
Here, examples of the polyester-based resin include polyethylene terephthalate, polybutylene terephthalate, and the like.Examples of the polyolefin-based resin include polyethylene, polypropylene, polymethylpentene, and an ethylene-propylene copolymer, and examples of the polyamide-based resin include: Nylon 6, Nylon 66 and the like.

The fineness of the splittable conjugate fiber of the present invention is from 1 to 9
dtex is preferred. More preferably, it is 2-6 dtex. If the fineness is less than 1 dtex, the card passing property is poor, and 9 dtex
This is because, if it exceeds 300, the fineness after division is large, and the flexibility of the nonwoven fabric cannot be obtained. The composite ratio (volume ratio) of the splittable composite fiber of the present invention is 70/30 to 3 from the viewpoint of spinnability.
0/70, preferably 60/40 to 40/60. The fineness of the finally obtained ultrafine fiber after division is preferably 0.6 dtex or less. More preferably, it is 0.3 dtex or less. 0.6dtex fineness of microfiber
By setting the content as described below, fine and numerous voids unique to the modified ultrafine fiber are formed, which contributes to an improvement in the liquid absorption rate.

The hydrophilic fibers used in the present invention include natural fibers such as cotton, regenerated fibers such as rayon and cupra, and synthetic fibers subjected to a hydrophilic treatment. Among them, rayon fibers Is preferably used from the viewpoint of handleability and versatility. The fineness of the hydrophilic fiber is 0.
8 to 3 dtex is preferred. More preferably, it is 1-2 dtex. If the fineness is less than 0.8 dtex, the card passing property is poor, and if it exceeds 3 dtex, the flexibility of the nonwoven fabric is impaired.

By mixing the splittable conjugate fiber and the hydrophilic fiber, excellent liquid absorption and flexibility can be obtained. The mixing ratio of the splittable conjugate fiber and the hydrophilic fiber is preferably such that the splittable conjugate fiber is mixed at 20 to 50% by weight and the hydrophilic fiber is mixed at 80 to 50% by weight. More preferably, the splittable conjugate fiber is 30 to 50% by weight and the hydrophilic fiber is 70 to 50% by weight. When the splittable conjugate fiber is less than 20% by weight or the hydrophilic fiber is more than 80% by weight, not only the flexibility of the nonwoven fabric is deteriorated, but also the wiping property when used for a wiping cloth or the like is deteriorated. If the splittable conjugate fiber exceeds 50% by weight or the hydrophilic fiber is less than 50% by weight, sufficient liquid absorbency cannot be obtained. The finally obtained ultrafine fibers after division are preferably at least 15% by weight in the whole nonwoven fabric. If the content of the ultrafine fibers is less than 15% by weight, the content of the undivided splittable conjugate fibers is large, and the formation of fine and numerous voids becomes insufficient.

If the splittable conjugate fiber and the hydrophilic fiber are within a predetermined range, other fibers may be mixed, but the mixing ratio must be less than 20% by weight. As the other fibers, for example, polyester fibers such as polyethylene terephthalate and polybutylene terephthalate; polyamide fibers such as nylon 6 and nylon 66; acrylic fibers; polyolefin fibers such as polyethylene and polypropylene; The above can be selected and used.

The fiber web comprising the splittable conjugate fiber and the hydrophilic fiber of the present invention may be a single layer or a laminate of two or more layers. For example, in the case of a single layer,
It is only necessary to mix 40% by weight of the hydrophilic fiber and 60% by weight of the splittable conjugate fiber. In the case of a two-layer structure, the hydrophilic fiber and the splittable conjugate fiber may satisfy a predetermined mixing ratio. For example, the mixing ratio of each layer may be changed. However, in consideration of productivity, a single-layer body in which two kinds of fibers are mixed is preferable.

The form of the fiber web is not particularly limited.
Parallel webs made of staple fibers, cross webs, semi-random webs, air-laid webs made of short fibers, wet papermaking webs, etc. can be used arbitrarily, taking into account the entanglement and separability of the high-pressure fluid flow treatment described below. Then, a fibrous web composed of staple fibers is preferred.

By subjecting the obtained fibrous web to a pore opening treatment, the liquid absorbing property and the flexibility are further improved, and an appropriate air permeability is obtained. The hole opening treatment of the nonwoven fabric may be performed by, for example, a method of treating with a high-pressure fluid flow, a method of piercing with a needle, or a method of vacuum suction. A processing method is preferred. As a method of processing with a high-pressure fluid flow, for example, a fibrous web is placed on an opening forming support such as a roll provided with a pattern net or a projection formed by weaving a monofilament or a metal wire, and a high-pressure fluid flow is injected. And a method of forming a nonwoven fabric by using a nonwoven fabric. As the “fluid” to be jetted, it is particularly preferable to use water from the viewpoint of process management. Further, the mode of the fluid to be ejected may be any of a spray shape, a column shape, and the like.

The conditions for the high-pressure fluid flow treatment may be appropriately set according to the basis weight and flexibility of the nonwoven fabric to be finally obtained. For example, when an attempt is made to obtain a nonwoven fabric having a basis weight of 30 to 60 g / m ² , an orifice having a pore size of 0.05 to 0.5 mm
From nozzles provided at intervals of ~ 1.5 mm, water pressure 20 ~
A columnar water flow of 70 kg / cm ² may be sprayed from the front and back sides of the nonwoven fabric one to four times each. The injection of the high-pressure fluid flow may be performed only on the support for forming the opening, or 20 to 60 kg.
After injecting a low-pressure fluid flow of / cm ² and preliminary confounding,
The fluid flow may be sprayed on the support for forming the aperture. Preliminary entanglement increases the strength of the resulting nonwoven.

When water is used as the fluid, the nonwoven fabric is dried by a suction drum dryer or the like. At this time, it is necessary to perform a heat treatment at a temperature at which the constituent fibers do not adhere to each other. This is because if the heat bonding treatment is performed at a temperature at which the constituent fibers are bonded to each other, the constituent fibers are substantially bonded to each other, and a highly flexible open nonwoven fabric cannot be obtained. At this time, the melting start temperature of the constituent fibers (differential scanning calorimetry (DSC) of the resin)
Assuming that Ts is the temperature at which the DSC curve shows a rise when performing the heat treatment, the heat treatment is preferably performed at a temperature of Ts−20 ° C. or less.

The shape, arrangement, area per hole, and porosity of the holes of the nonwoven fabric are determined by the form of the support for forming holes. The shape of the aperture in the present invention is not particularly limited, and may be any of a circle, an ellipse, a rectangle, a rhombus, and the like. Considered a hole. The arrangement of the apertures is not particularly limited, and may be any as long as they are regularly arranged in a lattice shape, a staggered shape, or the like. And a nonwoven fabric of stable quality cannot be obtained. Opening 1
The area per unit is 0.3 to 5.0 mm ² , and the porosity is 10 to 10.
Preferably it is 50%. In particular, the area is 0.5-3.
0 mm ^2, and more preferably the hole area ratio was 15% to 30%. If the open area is less than 0.3 mm ² or the open area ratio is less than 10%, the air permeability is insufficient, and the open area is 5.0 mm ^2.
When the pore ratio exceeds 50%, or when the porosity exceeds 50%, the proportion of the non-porous portion formed by the entanglement of the constituent fibers is small, and the amount of liquid absorption is limited.

[0020] The obtained nonwoven fabric with open pores is mixed with the splittable conjugate fiber in addition to the hydrophilic fiber, so that it is more flexible than the conventional conjugate fiber. The basis weight is also an important factor in achieving its characteristics. The basis weight is 20 ~
It is preferably 100 g / m ² , and particularly when used for gauze and sanitary materials, 30 to 60 g / m ² is good. If the basis weight is less than 20 g / m ² , the strength becomes weak because the thickness becomes thin, and the texture of the obtained nonwoven fabric also becomes poor. Conversely, if the basis weight is more than 100 g / m ² , large energy is required for the three-dimensional confounding in the high-pressure water flow treatment, and the texture is undesirably hard.

The obtained non-woven fabric with apertures is JIS L
The water absorption at 1018 (Method B) is 10 mm or more;
And the rigidity (Method A) in JIS L 1096 is 6
It achieves excellent liquid absorbency and flexibility of 0 mm or less. More preferably, the water absorption is 15 mm or more, and the
0 mm or less. When the water absorbency is less than 10 mm, the liquid absorbency is not sufficient, and when the softness exceeds 60 mm, the flexibility is poor.

Furthermore, the open nonwoven fabric of the present invention has a large number of openings formed therethrough from the front surface to the back surface of the nonwoven fabric, so that the nonwoven fabric is excellent in air permeability and JIS L 1096.
Is preferably 300 ml / cm ² · sec or more.
If the air permeability is less than 300 ml / cm ² · sec, when used as a sanitary material or the like that comes into direct contact with the skin, it causes stuffiness or stickiness, causing discomfort.

When the obtained nonwoven fabric is used as a sanitary material such as gauze, it absorbs body fluids quickly and has appropriate air permeability and permeability, thereby suppressing discomfort such as stuffiness. Furthermore, since it is rich in flexibility, it has excellent adhesion to an object such as skin. In addition, when used in a dry state such as a wiping cloth, not only can dirt and dirt in a state containing moisture be well captured, but also dirt can be captured and held in the opening. On the other hand, when used for wet tissues or wet wipers, the nonwoven fabric can be easily formed into a wet state, has excellent water retention, and the finally obtained ultrafine fibers act to wipe off and touch. A good thing is obtained.

[0024]

EXAMPLES Hereinafter, the contents of the present invention will be specifically described with reference to examples. The thickness, tensile strength, elongation at break, water absorption, bristles, air permeability, and tactile sensation of the obtained nonwoven fabric were measured as follows.

(Thickness) Thickness measuring machine (trade name: THICKNES
S GAUGE model CR-60A (made by Daiei Kagaku Seiki Seisakusho Co., Ltd.)
The measurement was performed with a load of 3 g applied per cm ^{2 of} the sample.

(Tensile strength, breaking elongation) JIS L 1
According to No.096, a sample piece with a width of 5 cm and a length of 15 cm is gripped at an interval of 10 cm, stretched at a pulling speed of 30 cm / min using a constant-speed tensile testing machine, and the load value and the elongation at the time of cutting are measured. did.

(Water Absorption Degree) According to the water absorption B method (Bilec test method) of JIS L 1018, five test pieces each having a width of 2.5 cm and a length of 15 cm were sampled in the vertical and horizontal directions, respectively. One end was immersed in water, and the average value of each water suction height was measured.

(Flexibility) According to the rigidity A method (45 ° cantilever method) of JIS L 1096, a test piece having a width of 2 cm and a length of 15 cm was placed in a vertical direction and a horizontal direction each for 5 times.
Samples were sampled, the length of movement of the test piece was measured using a cantilever type measuring instrument, and the average value in each of the vertical direction and the horizontal direction was obtained.

(Air permeability) Using a Frazier type testing machine,
It was measured according to JIS L 1096.

(Tactile Sensitivity) Tactile sensation when the nonwoven fabric as a sample was touched by hand was evaluated on a three-point scale.・ ・ ・: Soft, soft, and tangled with hands. Δ: The feel is good, but there is no feeling of being entangled in the hand. X: Hard, stiff, and uncomfortable.

Example 1 The first component was melted at an onset temperature of 25.
FIG. 1 (b) was polyethylene terephthalate at 0 ° C., and the second component was polypropylene at a melting onset temperature of 150 ° C.
Fineness 3.0 having a cross section arranged in a windmill shape as shown in
dtex, split-type composite fiber with a fiber length of 51 mm (Daiwa Spinning Co., Ltd.)
Was mixed with 70% by weight of rayon fiber (manufactured by Daiwabo Rayon Co., Ltd.) having a fiber length of 38 mm and a fiber length of 38 mm with a parallel card to produce a card web with a basis weight of 40 g / m ² . After the orifice hole diameter 0.13mm the obtained card webs were pre-entangled by double injection from a nozzle provided with a high-pressure columnar water flow pressure 40 kg / cm ² at 1mm intervals, hole forming support (Nippon Filcon Co., Ltd., 25 mesh, plain fabric) with a water pressure of 80 kg / cm ²
Was jetted three times to obtain a nonwoven fabric having a large number of openings penetrating from the front surface to the back surface of the nonwoven fabric. Furthermore, the nonwoven fabric uses a suction drum dryer,
The fiber was dried at 70 ° C. so as not to thermally bond the constituent fibers to each other to obtain an open nonwoven fabric. The thus obtained non-woven fabric having an opening had an opening area of about 1.0 mm ² and an opening ratio of about 25%. The content of the ultrafine fibers after division was 24% by weight.

Example 2 50% by weight of splittable conjugate fiber
In the same manner as in Example 1, except that the amount of the rayon fiber was changed to 50% by weight, the opening area of one hole was about 1.2 mm ² , the opening ratio was about 23%, and the content of the ultrafine fibers after splitting was 40. % By weight of the open nonwoven fabric was obtained.

Comparative Example 1 80% by weight of splittable conjugate fiber
In the same manner as in Example 1, except that the amount of the rayon fiber was changed to 20% by weight, the area of one opening was about 1.1 mm ² , the opening ratio was about 23%, and the content of the ultrafine fibers after splitting was 58%. % By weight of the open nonwoven fabric was obtained.

Comparative Example 2 Melting start temperature of the first component was 25
FIG. 1 shows polyethylene terephthalate at 0 ° C. and the second component as high-density polyethylene having a melting onset temperature of 125 ° C.
Rayon fibers having a fineness of 3.0 dtex, a fibrous length of 51 mm and a splittable conjugate fiber of 30 wt%, a fineness of 0.8 dtex and a fiber length of 38 mm (Daiwabo Rayon Co., Ltd.) having a cross section arranged in a windmill shape as shown in FIG. ) Was mixed at 70% by weight, and a card web having a basis weight of 40 g / m ² was prepared using a parallel card. Then, a water pressure of 40% was applied from a nozzle provided with orifices having a hole diameter of 0.13 mm at intervals of 1 mm in the obtained card web.
After a high-pressure columnar water flow of 2 kg / cm ² was sprayed twice and pre-entangled, a support for forming holes (Nippon Filcon Co., Ltd., 25
A high-pressure columnar water stream with a water pressure of 80 kg / cm ² was sprayed three times on a nonwoven fabric (mesh, plain fabric) to obtain a nonwoven fabric having a large number of openings penetrating from the front surface to the back surface of the nonwoven fabric. Furthermore, the nonwoven fabric was melted at 140 ° C. using a suction drum drier to melt the high-density polyethylene, and the constituent fibers were thermally bonded to each other to form an open nonwoven fabric. The thus obtained non-woven fabric having an opening had an opening area of about 1.0 mm ² and an opening ratio of about 25%. The content of the ultrafine fibers after division was 24% by weight.

[Comparative Example 3] One hole was formed in the same manner as in Example 1 except that a polyester fiber having a fineness of 1.6 dtex and a fiber length of 51 mm (manufactured by Teijin Limited) was used instead of the splittable conjugate fiber. An apertured nonwoven fabric having an area of about 1.0 mm ² and an aperture ratio of about 20% was obtained.

[Comparative Example 4] A high pressure columnar water flow of 40 kg / cm ² was applied twice from a nozzle in which orifices having a hole diameter of 0.13 mm were provided at 1 mm intervals in the card web of Example 1, and a water pressure of 80 was used.
A high-pressure columnar water flow of kg / cm ² was jetted twice, and further dried using a suction drum dryer at 70 ° C. so as not to thermally bond the constituent fibers to each other, to obtain a non-porous nonwoven fabric. The content of the ultrafine fibers after splitting was 26% by weight. Table 1 shows the physical properties of Examples 1 and 2 and Comparative Examples 1 to 4.

[0037]

[Table 1]

When Examples 1 and 2 and Comparative Examples 1 to 4 were used as gauze, Examples 1 and 2 had good adhesion to the skin and good air permeability, so that the body fluid was efficiently removed without stuffiness. Absorbed. On the other hand, in Comparative Example 1, the mixing ratio of the hydrophilic fibers was too small, and almost no body fluid could be absorbed. In Comparative Example 2, since heat bonding was applied, the texture was hard and the feeling of adhesion to the skin was not sufficient. In Comparative Example 3, the feeling of close contact with the skin was not sufficient, and in Comparative Example 4, since no holes were formed, there was no air permeability and the user was uncomfortable due to stuffiness.

[0039]

The perforated nonwoven fabric of the present invention realizes excellent liquid absorption, flexibility, and air permeability which cannot be obtained with conventional nonwoven fabrics. By the configuration, the ultrafine fiber having the irregular cross-sectional shape finally obtained forms a special fine and many voids, and the liquid absorption performance is dramatically improved in conjunction with the liquid absorption of the hydrophilic fiber I do. In addition, since the constituent fibers including the ultrafine fibers are not substantially adhered to each other and form openings, the texture is soft, and when the object is a human body, a comfortable feel is obtained, and the wiping cloth is provided. For example, when the target is an object, the target is not damaged. Therefore, the perforated nonwoven fabric of the present invention is suitable for sanitary materials such as gauze, bandages, disposable diapers, sanitary napkins, wet tissues, wiping cloths and the like.

[Brief description of the drawings]

FIGS. 1A to 1C show examples of fiber cross-sectional views of a splittable conjugate fiber used in the present invention.

[Explanation of symbols]

 1. First component 2. Second component

Claims (2)

[Claims] A nonwoven fabric comprising a splittable conjugate fiber composed of two different resins and having at least one component divided into two or more in a fiber cross section, and a hydrophilic fiber, and having a plurality of openings penetrating from the front surface to the back surface of the nonwoven fabric. In the nonwoven fabric in which the holes were formed, the constituent fibers were not substantially bonded to each other, and the water absorption (method B) according to JIS L 1018 was 1
An apertured nonwoven fabric having a hardness of 0 mm or more and a stiffness (method A) according to JIS L 1096 of 60 mm or less. 2. The perforated nonwoven fabric according to claim 1, wherein the splittable conjugate fiber is mixed with 20 to 50% by weight and the hydrophilic fiber is mixed with 80 to 50% by weight.