JPH101856A - Heat seal type nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the subject nonwoven fabric increased in the tensile strength in the direction perpendicular to its machine direction, reduced in the thermal shrinkage in the machine direction, and uniform in formation, by using heat seal type fibers under specified conditions. SOLUTION: This heat seal type nonwoven fabric is obtained by jointing heat seal type fibers (fiber length: 3-25mm; yarn fineness: 1-1.00 denier; aspect ratio: 25-2,000) under such conditions as to come to 61.2-3.0×10<5> in the constituent number of the fibers shown by the formula. This nonwoven fabric is suitable as a hygienic product such as paper diaper, napkin or pad for dealing with incontinence or mother's milk, or as an absorbing article such as wiper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-bondable nonwoven fabric, and more particularly to a heat-bondable nonwoven fabric suitably used for sanitary materials such as disposable diapers, napkins, incontinence pads, breast milk pads, and wipers.

[0002]

2. Description of the Related Art Conventionally, as a heat-bondable nonwoven fabric of this type, as described in Japanese Patent Publication No. 52-12830, heat-bondable conjugate fibers are aligned using a carding machine to obtain a predetermined basis weight. A nonwoven fabric formed by laminating and entangled as described above and then heat-treating the fibers to fuse each other is known.

[0003]

However, the above-mentioned conventional non-woven fabric uses a card machine, and the fibers are hooked by a needle cloth and arranged in the machine direction. Therefore, most of the fibers are in the machine direction (the flow direction of the non-woven fabric). And almost no orientation in the vertical direction. Therefore, the nonwoven fabric has a small tensile strength in the direction perpendicular to the machine direction,
It was not always satisfactory from the viewpoint of nonwoven fabric processing, such as a large shrinkage in the machine direction during heat treatment.

[0004]

The invention claimed in the present application is as follows. (1) Nonwoven fabric to which heat-adhesive fibers having a fiber length of 3 to 25 mm, a yarn thickness of 1 to 100 denier and an aspect ratio (fiber length divided by fiber diameter) of 25 to 2000 are joined. The heat-bondable nonwoven fabric, wherein the number of the composite fibers per cm ^{3 of the} nonwoven fabric is 61.2 to 3.0 × 10 ⁵ . Here, the number of fibers per 1 cm ³ is represented by the following equation.

(Equation 2) (2) The heat-adhesive fiber has a fiber length of 3 to 25 mm, a yarn thickness of 1 to 100 denier, and an aspect ratio of 50 to 150.
The heat-bondable nonwoven fabric according to the above (1), wherein the range is 0. (3) The heat-adhesive fiber has a fiber length of 3 to 25 mm, a yarn thickness of 1 to 100 denier, and an aspect ratio of 100 to 40.
The heat-bondable nonwoven fabric according to the above (1) or (2), wherein the range is 0. (4) The heat bonding according to any one of the above (1) to (3), wherein the thermoadhesive fiber is a composite fiber composed of at least a two-component resin and having a melting point difference of 10 ° C. or more. Nonwoven fabric. (5) The ratio (Mw / Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) of the heat-adhesive fibers forming the heat-adhesive nonwoven fabric, which is polymerized using a metallocene catalyst, is 1.5 to 3; (1) to (8), characterized in that it is formed of at least one polypropylene having a capacity of 0.8.
The heat-bondable nonwoven fabric according to any one of (4). (6) The heat-adhesive fibers forming the heat-adhesive nonwoven fabric are dimethylsilylene (2,3,5-trimethylcyclopentadienyl) (2 ′, 4 ′, 5′-trimethylcyclopentadienyl) hafnium dichloride, And dimethylsilylene (2,3,5-trimethylcyclopentadienyl) (2 ′, 4 ′, 5′-trimethylcyclopentadienyl) zirconium dichloride polymerized using a metallocene catalyst containing at least one selected from zirconium dichloride. The heat-bondable nonwoven fabric according to any one of the above (1) to (5), which is formed of polypropylene. (7) An absorbent article obtained using the nonwoven fabric according to any one of (1) to (6).

Hereinafter, the present invention will be described in detail. For the heat-bondable nonwoven fabric of the present invention, a heat-bondable single fiber and / or a heat-bondable conjugate fiber are used. By using these under the specific conditions defined in the present invention, as claimed in the present invention, excellent effects can be achieved over the prior art,
The effect is greater when using heat-adhesive conjugate fibers. The heat-bonding single fiber can be used from the following resin group. As for the heat-adhesive conjugate fiber, at least two components (hereinafter, referred to as component A and component B) can be used as raw materials and the following resins and the like can be used. Examples of the resin of the component A include polyolefins such as polypropylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, binary and terpolymers of propylene and other α-olefins, and polyamides. , Polyethylene terephthalate, polybutylene terephthalate,
Low-melting polyesters obtained by copolymerizing diol and terephthalic acid / isophthalic acid, polyesters such as polyester elastomers, fluororesins, mixtures of the above resins, and other spinnable resins can be used. Examples of the resin of component B include polyolefins such as polypropylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and binary or terpolymers of propylene and other α-olefins, and polyamides. ,
Polyethylene terephthalate, polybutylene terephthalate, low melting point polyester obtained by copolymerizing diol and terephthalic acid / isophthalic acid, polyesters such as polyester elastomer, fluororesin, a mixture of the above resins, and other spinnable resins can be used. When polypropylene is used as a raw material of the heat-adhesive fiber, the texture such as the flexibility of the nonwoven fabric is improved. At the same time, it is possible to obtain a nonwoven fabric having properties such as light weight and water levitation characteristic of polypropylene. The polypropylene is obtained by polymerization using a so-called Ziegler / Natta catalyst,
Any polymerized using a so-called metallocene catalyst can be used. As the polypropylene,
Number average molecular weight (M) polymerized using a metallocene catalyst
n) to the weight average molecular weight (Mw) (Mw / M
The effect obtained by the present invention is great when n) is 1.5 to 3.8. Metallocene catalysts, for example,
Polypropylene polymerized using a catalyst consisting of a combination of a metallocene compound and an aluminoxane, etc., has very high isotacticity consisting of a very highly controlled meso-bonded chain with almost no heterogeneous bonds or racemic bonds. Therefore, it can be preferably used in the present invention. The heat-bondable nonwoven fabric formed from the heat-bondable fibers using these polypropylenes is characterized by high strength, high flexibility, and high strength of the nonwoven fabric at high temperatures. In addition, since the fiber has particularly good heat resistance, even a non-woven fabric which is heat-bonded at a high temperature is hardly damaged by the fiber itself and damage at a heat bonding joint. Thereby, the effect that the obtained nonwoven fabric becomes higher in strength by these performances can be exhibited. As the metallocene compound that can be used as the metallocene catalyst, known compounds can be used. In particular, dimethylsilylene (2,3,5-trimethylcyclopentadienyl)
(2 ′, 4 ′, 5′-trimethylcyclopentadienyl) hafnium dichloride and dimethylsilylene (2,3,5-trimethylcyclopentadienyl)
When at least one selected from (2 ′, 4 ′, 5′-trimethylcyclopentadienyl) zirconium dichloride is used, the heat-bonding nonwoven fabric obtained by using the polypropylene obtained thereby as a raw material has a favorable effect. . As the polypropylene, for example, those having a weight average molecular weight (Mw) in the range of 50,000 to 1,000,000 can be used.
00 to 600,000. When the polypropylene having a Mw / Mn of 1.5 to 3.8 is used, the effect obtained in the present invention is large, more preferably 1.5 to 3.5, and more preferably 1 to 3.5. 0.8-3.0
It is. The polypropylene used has a melting point of 160-1.
Those at 68 ° C. are more preferred.

The difference between the melting points of the A and B component resins is preferably 10 ° C. or more. Thereby, the melting point of the low melting point component or more,
If the heat treatment is performed at a temperature lower than the melting point of the high melting point component, the low melting point component of the composite fiber is melted and the fiber bonding point is thermally bonded, leaving the high melting point component as it is to form a three-dimensional heat-bondable nonwoven fabric having a network structure. Can be formed. Examples of such a combination of the A and B resin components include, for example, high density polyethylene / polypropylene, low density polyethylene /
Propylene / ethylene / butene-1 crystalline copolymer, high density polyethylene / polyethylene terephthalate, nylon-6 / nylon 66, low melting point polyester / polyethylene terephthalate, polypropylene / polyethylene terephthalate, polyvinylidene fluoride / polyethylene terephthalate, linear low density A mixture of polyethylene and high-density polyethylene / polyethylene can be exemplified.

[0007] The form of the conjugate fiber is a sheath-core type, a side-by-side type, a multilayer type having three or more layers, a hollow multilayer type, a heterogeneous multilayer type, a sea-island type, and the like. Any structure may be used as long as at least a part of the surface is formed.

[0008] In the composite fiber, the low melting point resin and the high melting point resin have a composite ratio of 10 to 90% by weight of the low melting point resin and 90 to 10% by weight of the high melting point resin. More preferably, the low melting point resin is 30 to 70% by weight, and the high melting point resin is 70 to 30% by weight. When the low melting point resin component is less than 10% by weight,
The tensile strength of the heat-bonding nonwoven fabric made of the composite fiber is insufficient. In the case of a heat-bondable single fiber, a short fiber contact of the heat-bondable single fiber can be thermally bonded or chemically bonded using a chemical binder (powder or liquid). In the case of a heat-adhesive single fiber, short fibers of the heat-adhesive conjugate fiber are mixed, and the melting point of the low-melting component of the heat-adhesive composite fiber is higher than the melting point of the higher-melting component, If the heat treatment is performed at a temperature equal to or lower than the melting point, thermal bonding can be performed.

The thickness of the heat-adhesive fiber is 1 to 100 denier, preferably 1.5 to 32 denier, and more preferably 1.5 to 18 denier. When the thickness of the fiber is less than 1 denier, the strength of the nonwoven fabric is reduced. When the thickness of the fibers exceeds 100 denier, the fibers are entangled with each other, so that a web having a uniform texture cannot be produced.

The fiber length of the heat-adhesive fiber is preferably from 3 to 25 mm, more preferably from 3 to 15 mm, even more preferably from 5 to 12 mm. If the fiber length is less than 3mm,
The strength of the nonwoven is reduced. If the fiber length exceeds 25 mm, the fibers are entangled with each other, making it difficult to produce a web having a uniform texture.

In the present invention, in order to balance the strength and the formation of the nonwoven fabric, the aspect ratio (the value obtained by dividing the fiber length by the diameter), which represents the relationship between the fiber length and the fiber thickness (diameter) of the nonwoven fabric, is important. It is. The aspect ratio in the present invention is 25 to 2,000, preferably 50 to 1500, and more preferably 100 to 400. For example,
The diameter of an olefin-based composite fiber having a thickness of 100 denier is 1
23 μm, the fiber length is 25 mm, the aspect ratio is 203, and the diameter of the composite fiber having a thickness of 1 denier is 12 μm.
When the fiber length is 3 mm, the aspect ratio is 250. By using fibers having such an aspect ratio, fibers can be randomly laminated by the airlaid method described later.

When calculated from the above aspect ratio, fiber length and fiber thickness (diameter), the number of the composite fibers per cm ^{3 of} the nonwoven fabric is 61.2 to 3.0 × 10 ^5. Preferred, more preferably 191 to 2.0
× 10 ⁵ , more preferably 409 to 2.0 × 10 ⁵
It is a book.

The composite fiber used in the heat-bondable nonwoven fabric of the present invention can be produced, for example, by the following steps. The resin of the core component and the sheath component is melted, and for example, the number of holes is 10
Discharge from a composite spinneret of 0 to 350. At this time,
The undrawn yarn is cooled by air cooling just below the die. Discharge rate 100-200 g / min., Take-off speed 40-130
By picking up at 0m / min.
A denier undrawn yarn is produced. The undrawn yarn is drawn while setting the speed between the rolls heated from 60 ° C. to 120 ° C. between 1: 2 and 1: 5 to produce a drawn yarn of 1 denier to 100 denier. After applying a surface agent to the drawn yarn with a touch roll, the drawn yarn is passed through a box-type crimping machine to produce a crimped tow. The number of crimps is preferably from 0 to 25 peaks per inch. The tow is about 1
Since it contains 0% moisture, it is dried at 60 ° C to 120 ° C using a dryer. The dried tow is cut into fibers of a fixed fiber length in the range of 3 mm to 25 mm using a push-cut type cutter. Such a fiber length is substantially shorter than the fiber used for the carded nonwoven fabric.

The heat-bondable nonwoven fabric of the present invention can be produced as follows using the composite fiber produced as described above and an air-laid apparatus. As shown in FIGS. 1 to 3, the airlaid apparatus 1 has a casing 2 having a trapezoidal cross section having an opening only on the lower surface, fiber inlets 3 and 4 provided at both ends of the casing 2, Web forming heads 5 and 6 comprising rotatable cylindrical screens 5a and 6a provided opposite to the inlets 3 and 4 and parallel to the side surfaces of the casing 2, respectively.
Between the needle rolls 5b and 6b and both ends of the cylindrical screens 5a and 6a and the both end surfaces of the casing 2 so as to be in sliding contact with the inner walls of the cylindrical screens 5a and 6a, respectively. It is mainly composed of the provided fiber circulation zones 7 and 8.
A net conveyor 9a is provided directly below the lower surface of the air laid device 1, and a pair of drive rolls 17a and 17b and a suction device 10 are attached to the net conveyor 9a. Further, as an apparatus in the next step, a suction dryer 12 for thermally bonding the conjugate fibers constituting the web and a net conveyor 9b for passing the web therethrough are provided, and a pair of the net conveyors 9b for moving the net conveyor 9b below the pair. The drive rolls 17c and 17d are attached, and the compression roll 11 is provided on the drive roll 17c with the net conveyor 9b interposed therebetween. Further, a pair of drive rolls 19a and 19b for driving the feed roll 18 for feeding the produced heat-bondable nonwoven fabric 13 and the take-up roll 14 are provided.

In the above apparatus, the cut conjugate fibers are mechanically spread by a fiber spreader (not shown), and then sent to a cotton circulation duct which passes through fiber bins 3 and 4 via stock bins. . At this point, the fiber bundles are almost completely unwound. Fiber 1 sent to fiber inlets 3 and 4
5 is a cylindrical screen 5a, 6a and a fiber circulation zone 7,
While being moved in the direction of arrow C ₁ C ₂ C ₃ C _{4 and} the direction of arrow D ₁ D ₂ D ₃ D ₄ in FIG. 2, the passage formed by 8 is mixed and circulated. The circulated fibers are combined with needle rolls 5b and 6b rotating in the directions of arrows A and A 'and arrows B and B, respectively.
Due to the centrifugal force and shearing action generated by the rotation of both the cylindrical screens 5a and 6a rotating in the 'direction, the liquid is discharged from the rotating cylindrical screens 5a and 6a. The discharged fibers are sucked from below the casing 2 by the suction device 10 and collected at the upper portion of the net conveyor 9a. The collected web 16 is compressed between the web compression roll 11 and the net conveyor 9b. At this point, the collected fibers are laminated and oriented in random directions.

After the web 16 is compressed by the web compression roll 11, it is supplied to the suction dryer 12, where the melting point is higher than the melting point of the low melting point component and lower than the melting point of the high melting point component, for example, at a temperature of 90 ° C. to 170 ° C. for 3 seconds. By heating for 10 seconds, the low melting point component of the conjugate fiber is melted and the high melting point component remains as it is, thereby forming the heat-bonding nonwoven fabric 13 having a three-dimensional network structure, and the winding roll 14 It is wound up.

In order to arrange the composite fibers conveyed by air more randomly, a sieve or a net made of various meshes may be used as a production method, and specifically, a screen is preferably used.

A cylindrical screen 5 used for an air laid device
The shape of the holes of the screens a and 6a is usually horizontally long, but preferably 1 to 3 mm in length and 15 to 30 mm in width. The shape of the hole may be a circle, a triangle, a square, a polygon, an ellipse, or the like, in addition to the horizontally long shape. Screen aperture ratio is 2
0% to 50% is preferred. By selecting such a hole diameter and an opening ratio, a web having a uniform formation can be produced.

The heat-bonding nonwoven fabric of the present invention is subjected to a heat treatment with a suction dryer 12 after forming the web, so that the intersections of the fibers are heat-sealed. This heat treatment may be performed using a heating device such as a heat calender roll instead of the suction dryer 12. The basis weight of the obtained non-woven fabric is not particularly limited, but is about 10 to 1000 g / m
² About 10-60g /
m ^2, about 10 to 500 g / m ² when the wiper is about 10 to 1000 g / m ² when the filter. The apparent density of the nonwoven fabric is not particularly limited, but is preferably about 0.017 to 0.11 g / cm ^{3 in} consideration of the texture. A higher density nonwoven fabric can be obtained by subjecting the nonwoven fabric to post-processing such as hot pressing or hot roll processing. The nonwoven fabric having a high density is used for a filter, a heat insulating material, and the like. When the heat-bondable nonwoven fabric of the present invention is heat-sealed using a heat calender roll, the thermocompression bonding area ratio is 10 to 3
It is desirable to set it to 0%. If the compression area ratio is less than 10%, the pull-out resistance and the strength of the nonwoven fabric are inferior, and if it exceeds 30%, the hand of the nonwoven fabric becomes hard. When the non-woven fabric is made of fibers using at least one material made of polypropylene polymerized using a metallocene catalyst, the polypropylene has excellent heat resistance, so that the fibers themselves are damaged by high-temperature processing when heat-sealing the fibers. And the damage at the fusion point is also small. Therefore, the nonwoven fabric has high strength, and the decrease in the strength of the nonwoven fabric and the decrease in rigidity in a high-temperature environment are extremely small.
When this nonwoven fabric is used for a filter or the like, a decrease in strength, a decrease in heat resistance, and the like are effectively reduced even when high-temperature sterilization treatment or high-temperature filtration is performed.

The heat-bondable nonwoven fabric of the present invention can be used for various purposes alone or by laminating, sewing, heat-sealing, etc. with other members. For example, when it is used as one member of a pants-type disposable diaper, it can be used for a part requiring both texture and strength, such as a surface material and a back sheet. Of course, when used for the diaper or the like, it can be used in combination with another member such as an elastic member for tightly attaching the trunk or the leg and the heat-bondable nonwoven fabric. The heat-bondable nonwoven fabric may be laminated with another nonwoven fabric, tissue, web, film, or the like, and used as a cover material for the surface material or a cover material for the back surface material.

The heat-bondable nonwoven fabric of the present invention can be used for wipers of furniture, cars, etc. by adhering various lubricants and the like. Also, the heat-bondable nonwoven fabric is folded, further molded into a tubular shape, the heat-bondable nonwoven fabric is formed into a cylindrical shape by winding, or the heat-bondable nonwoven fabric is rolled while being heated, and the layer is formed. The filter material can be obtained by post-processing such as molding into a heat-fused cylindrical shape.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Table 1 shows the physical properties and the like of the nonwoven fabric. The definition and measurement method of the physical property values and the like of the heat-bondable nonwoven fabric in this example are as follows. The strength and heat shrinkage of the heat-fusible nonwoven fabric of Table 1 were defined and measured as follows. (1) Strength Tensile strength in the direction perpendicular to the machine direction of the nonwoven fabric was measured and determined as the strength. Using Shimadzu Autograph AG500 manufactured by Shimadzu Corporation Sample length: 15 cm x 5 cm Grip distance: 10 cm Pulling speed: 10 cm / min. (2) Heat Shrinkage The heat shrinkage of the nonwoven fabric in the machine direction was defined as the heat shrinkage. Hot air circulation type dryer used Temperature 145 ° C Time 5 minutes Sample size: 25cm × 25cm

[0023]

【Example】

Example 1 Polymerized using a Ziegler / Natta catalyst as a core component, MFR = 15 g / 10 min (JIS K7210 condition 1)
4) Polypropylene, polymerized using a Ziegler / Natta catalyst as a sheath component, MI = 16.5 g / 1
A high-density polyethylene of 0 minutes (JIS K7210 condition 4) is picked up by using a composite spinneret having a discharge ratio of 5 to 5 and a number of holes of 350 at a discharge rate of 200 g / min. And a take-up speed of 721 m / min. A denier undrawn yarn was produced. At the time of spinning, the yarn is cooled by air cooling just below the spinneret.
The undrawn yarn was drawn at a speed between rolls heated to 90 ° C. at a ratio of 1: 4, and a drawn yarn of 2 denier was produced. After applying a surface agent to the drawn yarn with a touch roll, the yarn was passed through a box-type crimping machine to produce a tow having 14 zigzag crimps per inch. Since this tow contains water, it is dried at 90 ° C. using a drier, and then, using a push-cut type cutter, the fiber length is 5 mm.
Was produced. The composite fiber was fed and passed through a fiber opening machine, and after mechanically fiber opening, the fiber was supplied to an air-laid apparatus shown in FIGS. That is, the opened composite fiber 15 was fed into the fiber inlets 3 and 4 via the stock bin and the cotton feeding circulation duct, and the fiber was discharged from the rotating web forming heads 5 and 6. A suction device 10 for operating the discharged fibers at 90 m / min.
Was collected by a net conveyor 9a to produce a web 16. After being compressed by the web compression roll 11, the sheath component is heat-treated at 150 ° C. for 3 seconds using a suction drier 12 to melt-bond the high-density polyethylene of the sheath component to a basis weight of 25 g / m ² , a thickness of 1 mm, and a density of 0.1 mm. 025
g / cm ³ of the heat-adhesive nonwoven fabric 13 was produced and wound on a take-up roll 14. Table 1 shows the physical properties and the like of the nonwoven fabric. When the texture of the nonwoven fabric was evaluated by five persons, it was determined that the flexibility was good and the texture was good.

Example 2 The discharge amount during spinning was 140 g / min.
9 m / min., Non-drawn yarn of 3.4 denier, drawn yarn of 1 denier, fiber length of 3 mm, and non-woven fabric produced under the same conditions as in Example 1 except that heat treatment was further performed after heat treatment. did. In the hot press working, the upper and lower hot press plates are heated at 140 ° C. for 5 seconds and a pressure of 5 kg / cm ² without a spacer.
Was performed under the following conditions. The produced nonwoven fabric has a basis weight of 25 g / m.
² , the thickness was 0.25 mm, and the density was 0.100 g / cm ³ .

Example 3 Using a spinneret having 60 holes, the discharge amount during spinning was 20
A nonwoven fabric was produced under the same conditions as in Example 1 except that the yarn was drawn at 0 g / min. And at a drawing speed of 882 m / min. The produced nonwoven fabric has a basis weight of 25 g / m ² and a thickness of 1
mm and a density of 0.025 g / cm ³ .

Example 4 A nonwoven fabric was produced under the same conditions as in Example 3 except that the fiber length of the fiber was 10 mm. The prepared nonwoven fabric had a basis weight of 25 g / m ² , a thickness of 1 mm, and a density of 0.025 g / cm ^3.
Met.

Example 5 MFR = 10 g / 10 min polymerized using a Ziegler / Natta catalyst as a core component (JIS K7210 condition 1)
4) Polypropylene is used, a spinneret having 100 holes is used, the discharge amount during spinning is 200 g / min., The yarn is water-cooled at the time of spinning, and the drawing speed is 53 m / min. A nonwoven fabric was produced under the same conditions as in Example 1 except that the undrawn yarn, the drawn yarn of 100 denier, and the fiber length were 25 mm. The prepared nonwoven fabric had a basis weight of 25 g / m ² , a thickness of 1.5 mm, and a density of 0.0
It was 17 g / cm ³ .

Example 6 A nonwoven fabric was produced under the same conditions as in Example 1 except that the fiber length was 25 mm. The prepared nonwoven fabric has a basis weight of 23.8 g.
/ M ² , thickness 1.4 mm, and density 0.017 g / cm ³ .

Example 7 A spinning nozzle having 60 holes was used, and the discharge amount during spinning was 18
0 g / min., A drawing speed of 900 m / min., A 30 denier undrawn yarn, an 8 denier drawn yarn,
A nonwoven fabric was produced under the same conditions as in Example 1 except that the fiber length was 15 mm. The produced nonwoven fabric has a basis weight of 27.
5 g / m ² , thickness 1.1 mm, density 0.025 g / cm ³
Met.

Example 8 A nonwoven fabric was produced under the same conditions as in Example 7 except that the fiber length of the fiber was 25 mm. The produced nonwoven fabric had a basis weight of 25 g / m ² , a thickness of 1.25 mm, and a density of 0.020 g.
/ Cm ³ .

Example 9 Using a spinneret having 60 holes, the discharge amount during spinning was 20
A nonwoven fabric was produced under the same conditions as in Example 1 except that the yarn was drawn at 0 g / min. And at a drawing speed of 882 m / min. . The prepared nonwoven fabric has a basis weight of 2
2.5 g / m ² , thickness 0.9 mm, density 0.025 g /
cm ³ .

Comparative Example 1 The fiber length of Example 1 was 38 mm, and the fiber length was 38 mm.
A nonwoven fabric was produced under the same conditions as in Example 1 except that the following conditions were satisfied and a carding machine was used during the production of the web. The produced nonwoven fabric had a basis weight of 25 g / m ² , a thickness of 1 mm, and a density of 0.025 g / cm ³ .

Example 10 A heat-bondable composite fiber of polypropylene (core) / polyethylene (sheath) was produced in the same manner as in Example 1. Further, an airlaid web was obtained by the same manufacturing method as in Example 1 and further processed at 150 ° C. for 3 minutes under the same conditions to obtain a heat-adhesive nonwoven fabric. The nonwoven fabric has a basis weight of 25 g / m ² , a thickness of 1 mm, and a density of 0.02.
It was 5 g / cm ³ . However, the polypropylene used here was polymerized using a metallocene catalyst and had a melting point of 163.
6 ° C., weight average molecular weight (Mw) 218,000, Mw /
It was a polypropylene having an Mn of 2.4. In addition, the polypropylene has a metallocene catalyst such as methylaluminoxane and dimethylsilylene (2,3,5-trimethylcyclopentadienyl) (2 ′, 4 ′, 5′-trimethylcyclopentadienyl) hafnium dichloride and dimethylsilylene ( Polymerized using a mixture of 2,3,5-trimethylcyclopentadienyl) (2 ′, 3 ′, 5′-trimethylcyclopentadienyl) hafnium dichloride. As the polyethylene, a high-density polyethylene polymerized using the same Ziegler / Natta catalyst as in Example 1 was used. Table 1 shows the physical properties and the like of the nonwoven fabric.
It writes in. The obtained nonwoven fabric had high strength. Also, when the texture of the nonwoven fabric was evaluated by five people,
Both flexibility and texture were good. The texture was better than the nonwoven fabric obtained in Example 1.

Example 11 The nonwoven fabric obtained in Example 10 was subjected to hot pressing in the same manner as in Example 2. However, in the hot press, the temperature of the hot press plate was 145 ° C., the time was 5 seconds, and the pressure was 5 kgf /
It was carried out under the conditions of cm ^2. The obtained nonwoven fabric has a basis weight of 25.
g / m ² , thickness 0.24 mm, density 0.104 g / cm ³
Met. Table 1 shows the physical properties and the like of the nonwoven fabric. The obtained nonwoven fabric was strong. Example 12 A commercially available paper diaper having a substantially I-shaped cross section of a railroad rail was used, and only the surface material of the paper diaper was substantially replaced with the heat-adhesive nonwoven fabric described in Example 1. This commercially available disposable diaper uses a polyethylene / polypropylene heat-fusible composite fiber staple, and uses a non-woven fabric having heat-fused intersections of the fibers as a surface material, and a pulp and a highly water-absorbent resin as main components. , And a polyethylene film as the backing material. Only the surface material was cut off from the diaper with a knife. The heat-adhesive nonwoven fabric obtained in Example 1 was laminated on the cut surface material. Further, the heat-bondable non-woven fabric and the non-woven fabric near the remaining leg portions were heat-sealed. The remaining heat-bondable nonwoven fabric was cut off with scissors to obtain a disposable diaper on which the heat-bondable nonwoven fabric was disposed as a surface material.
This diaper had a large strength in the lateral direction (with respect to the longitudinal direction) of the surface material, had a bulky and soft texture, and was suitable as a paper diaper.

[0035]

[Table 1] As is clear from the results in Table 1, the heat-bondable nonwoven fabric is constituted by the number of components shown in the claims,
The tensile strength in the direction perpendicular to the machine direction of the nonwoven fabric increased, and the heat shrinkage in the machine direction of the nonwoven fabric decreased. In addition, since the fiber length of the fibers used in the heat-bondable nonwoven fabric of the present invention is shorter than that of the card nonwoven fabric, the number of constituents increases, so that the dispersion of fibers becomes less dense and dense, and the formation of the nonwoven fabric becomes uniform. . Further, since the fibers were laminated, the density was lower and the air permeability was higher than that of the card nonwoven fabric in which the fibers were hooked and oriented. Further, the heat-bonding nonwoven fabric made of a composite fiber using polypropylene polymerized with a metallocene catalyst as one component of the composite had high strength. In the embodiment of the present invention, the example of the heat-adhesive conjugate fiber is shown as the heat-adhesive fiber. However, the use of a single heat-adhesive fiber can also provide the sufficient effect claimed in the present application.

[0036]

The heat-bondable nonwoven fabric of the present invention has a problem that the tensile strength in the direction perpendicular to the machine direction of the nonwoven fabric is small because the nonwoven fabric is formed by using a specific number of specific heat-bondable conjugate fibers. And the tensile strength in that direction can be increased, and the heat shrinkage of the nonwoven fabric in the machine direction can be reduced. Further, the heat-bonding nonwoven fabric of the present invention has a shorter fiber length and a larger number of components than the card method nonwoven fabric, so that the density of fibers is reduced, and the formation of the nonwoven fabric can be made uniform. Further, since the fibers are laminated, the density becomes smaller and the air permeability can be increased as compared with a card nonwoven fabric in which the fibers are hooked and oriented.

[Brief description of the drawings]

FIG. 1 is a side view of an apparatus for producing a nonwoven fabric of the present invention.

FIG. 2 is a partially cutaway plan view of the airlaid apparatus 1 in the apparatus of FIG.

FIG. 3 is a cross-sectional view of the device of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Airlaid apparatus, 2 ... Casing, 3, 4 ... Fiber inlet, 5, 6 ... Web forming head, 5a, 6a
... cylindrical screen, 5a '... holes in cylindrical screen, 5
b, 6b: needle roll, 7, 8: fiber circulation zone,
9, 9a, 9b: net conveyor, 10: suction device, 11: web compression roll, 12: suction dryer, 13: heat-adhesive nonwoven fabric, 14: winding roll, 15: spread conjugate fiber, 16: web , 17
a, 17b, 17c, 17d: drive roll, 18: feed roll, 19a, 19b: drive roll.

Claims (7)

[Claims] 1. A fiber length of 3 to 25 mm and a yarn thickness of 1 to 100.
Denier, and an aspect ratio A nonwoven thermal bonding fibers are bonded in the range of (the fiber length divided by the diameter of the fiber) is 25 to 2000, the configuration number of the fibers per the nonwoven fabric 1 cm ³ 61.2 to 3.0 × 10 ⁵ heat-bondable nonwoven fabrics. Here, the number of fibers per 1 cm ³ is represented by the following equation. (Equation 1) 2. The heat-adhesive fiber has a fiber length of 3 to 25 mm,
Yarn thickness 1-100 denier and aspect ratio 50
The heat-bondable nonwoven fabric according to claim 1, wherein the non-woven fabric has a thickness of from 1500 to 1500. 3. The heat-adhesive fiber has a fiber length of 3 to 25 mm,
Yarn thickness 1-100 denier and aspect ratio 10
The heat-bondable non-woven fabric according to claim 1, wherein the non-woven fabric has a range of 0 to 400. 4. 4. The heat-adhesive fiber according to claim 1, wherein the heat-adhesive fiber is a composite fiber composed of at least a two-component resin and having a melting point difference of 10 ° C. or more. Non-woven fabric. 5. The ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) polymerized using a metallocene catalyst, wherein the ratio of the weight average molecular weight (Mw) is (Mw /
Mn) is formed of at least one polypropylene having a value of 1.5 to 3.8.
5. The heat-bondable nonwoven fabric according to any one of items 4 to 4. 6. The heat-adhesive fiber forming the heat-adhesive nonwoven fabric is dimethylsilylene (2,3,5-trimethylcyclopentadienyl) (2 ′, 4 ′, 5′-trimethylcyclopentadienyl) hafnium Using a metallocene catalyst containing at least one selected from dichloride and dimethylsilylene (2,3,5-trimethylcyclopentadienyl) (2 ′, 4 ′, 5′-trimethylcyclopentadienyl) zirconium dichloride The heat-bondable nonwoven fabric according to any one of claims 1 to 5, wherein the non-woven fabric is formed of polymerized polypropylene. 7. An absorbent article obtained by using the nonwoven fabric according to any one of claims 1 to 6.