WO1997048846A1

WO1997048846A1 - Nonwoven short fibre fabric and absorbent article made by using same

Info

Publication number: WO1997048846A1
Application number: PCT/JP1997/002073
Authority: WO
Inventors: Koki Nagano; Shigeru Hirabayashi
Original assignee: Chisso Corporation
Priority date: 1996-06-19
Filing date: 1997-06-16
Publication date: 1997-12-24
Also published as: AU3107797A; EP0906981A1; US20020016120A1; JP3219250B2; EP0906981A4; CA2256550A1

Abstract

A nonwoven short fibre fabric which comprises short fibers which have a fibre length of 3 to 25 mm and a single yarn fineness of 1 to 100 denier and which are dispersed and piled up, and nodes of which are bonded to one another. Fibre wads composed of short fibres and having a volume of at least 1 mm3 in the nonwoven fabric of 20 g are five or less in number, and the nonwoven short fibre fabric has a specific volume of 40 to 200 cm?3?/g. The nonwoven fabric can provide a bulky nonwoven fabric functioning sufficiently to contribute to bulkiness due to fibres, and is suitably used for sanitary materials such as disposable diapers, napkins, pads for incontinence, pads for mother's milk, or wipers.

Description

Description Short fiber nonwoven fabric and absorbent article using the same

The present invention relates to a short-fiber nonwoven fabric, and more particularly, a short-fiber nonwoven fabric suitably used for sanitary materials such as disposable diapers, napkins, incontinence pads, breast milk pads, wipers, and the like, and an absorbent material using the short-fiber nonwoven fabric. Regarding goods. Background art

Conventionally, as this kind of short-fiber nonwoven fabric, as described in Japanese Patent Publication No. 52-12830, the heat-adhesive conjugate fibers are aligned using a card machine to achieve a specified basis weight. A nonwoven fabric formed by laminating and entangled in a manner as described above and then heat-treating to fuse the fibers together is known.

However, the above-mentioned conventional nonwoven fabric uses a card machine, and the fibers are hooked by a needle cloth and arranged in the machine direction, so that the bulkiness that the fibers can contribute to the nonwoven fabric has been lost. Therefore, a bulky nonwoven fabric that sufficiently functions to contribute to the bulkiness of the fibers has not been obtained, and it was not always satisfactory.

An object of the present invention is to improve these drawbacks and to provide a bulky nonwoven fabric in which fibers have a sufficiently high bulkiness that can contribute to the nonwoven fabric. Disclosure of the invention

The short-fiber nonwoven fabric of the present invention and an absorbent article using the same are as follows. (1) The fiber length is 3 to 25 mm and the single yarn fineness is 1 to 100 denier A non-woven fabric in which one or more types of short fibers are dispersed and deposited, and the intersections of the short fibers are bonded to each other, and the specific volume of the non-woven fabric is 40 to 200 cm ³ / g. A short-fiber nonwoven fabric, wherein the number of fiber lump having a volume of l mm ³ or more composed of the short fibers present in the nonwoven fabric is 5 or less per 20 g of the nonwoven fabric.

(2) The short-fiber nonwoven fabric according to (1), wherein the short fiber has a fiber length of 5 to 10 mm.

(3) The short-fiber nonwoven fabric according to the above (1), wherein at least one of the short fibers is a short fiber having a helical crimp of 3 to 20 mountains Z inches (2.54 cm). .

(4) The short-fiber nonwoven fabric according to the above (1), wherein at least one of the short fibers is a thermoplastic fiber.

(5) The short-fiber nonwoven fabric according to the above (1), wherein at least one of the short fibers is an olefin- or polyester-based thermoplastic short fiber.

(6) The short-fiber nonwoven fabric according to the above (1), wherein at least one of the short fibers is a thermoplastic composite short fiber containing a heat-fusible component as one component in the fiber.

(7) At least one of the short fibers is a short fiber having an eccentric sheath-core structure in which high-crystalline polypropylene is used as a core component and high-density polyethylene is used as a sheath component. The short-fiber nonwoven fabric according to the above.

(8) Absorbent material using short-fiber nonwoven fabric according to any one of (1) to (7) above ππο Brief description of drawings

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

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

FIG. 3 is a cross-sectional view of the device of FIG. 2 taken along the line EE ′ in the direction of the arrow. BEST MODE FOR CARRYING OUT THE INVENTION

The fibers used in the short-fiber nonwoven fabric of the present invention include natural fibers such as pulp and cotton, rayon (regenerated fiber), acetate (semi-synthetic fiber), and nylon, vinylon, polyester, acryl, Examples include synthetic fibers such as polyethylene, polypropylene, and polystyrene. In essence, any type of fiber can be used as long as it adheres when a binder is used and does not impair the uniformity of the nonwoven fabric, but a powdery binder that falls as small particles or a water solution that requires drying Thermoplastic fibers are preferred which have a heat-bonding property that allows the intersections of the fibers to adhere in a short period of time by heat treatment without using a conductive binder.

The fiber length of the short fibers constituting the short fiber nonwoven fabric of the present invention needs to be in the range of 3 to 25 mm, preferably 3 to 15 mm, and more preferably 5 to 1 Omm. In particular, when the crimp is helical, the number of crimps is about 5 metric inches (2.54 cm), so that the fiber length of a single crimp is 5 mm and the number of crimps is two. The optimum fiber length is 1 Omm, which is the length of the wound fiber. When the fiber length is less than 3 mm, the strength of the nonwoven fabric is reduced. If the fiber length exceeds 25 mm, it is difficult to produce a uniform web because the fibers are entangled before passing through a sieve or screen.

The thickness of the fiber is from 1 to 100 denier, preferably from 1.5 to 35 denier, more preferably from 1.5 to 20 denier. When the thickness of the fiber is less than 1 denier, the fiber density in the cylindrical screen increases, and a uniform web cannot be produced. Also, if the fiber thickness exceeds 100 denier, a uniform force can be produced because the force between the fibers increases. Peg.

Specific volume of the short fiber nonwoven fabric of the present invention is 4 0~ 2 00 cm ³ Zg, good or Ku is 7 0~ 1 5 0 cm Zg. If the specific volume of the nonwoven fabric is less than 4 O cm ³ / g, the nonwoven fabric becomes hard and is not preferable. On the other hand, if the specific volume of the nonwoven fabric exceeds 200 cm ³ Zg, the strength of the nonwoven fabric becomes small, which is not preferable.

Further, in the short-fiber nonwoven fabric of the present invention, the number of fiber lump having a volume of 1 mm ³ or more in the nonwoven fabric needs to be 5 or less per 20 g of the nonwoven fabric. If the amount of the fiber lumps having the specific size mixed in the nonwoven fabric exceeds the above range, the nonwoven fabric becomes non-uniform, a rough feeling occurs, and the color of the nonwoven fabric becomes uneven due to the fiber lumps. Any inconvenience occurs and is not preferred.

When the fiber used in the short-fiber nonwoven fabric of the present invention is a composite fiber composed of at least two components (hereinafter, referred to as component (A) and component (B)), the following resins and the like can be used as a raw material.

Examples of the resin (A) include polypropylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and a binary or terpolymer of propylene with another α-olefin. Polyolefins; Polyamides; Polyethylene terephthalate, Polybutylene terephthalate, Polyesters such as low-melting-point polyesters copolymerized with diol and terephthalic acid / isophthalic acid, and polyester elastomers; Fluororesins A mixture of the above resins, and other spinnable resins.

(Ii) As the resin of the component, for example, polypropylene, high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, a binary or terpolymer of propylene with other α-olefins Etc. Polyolefins; Polyamides; Polyethylene terephthalate, polybutylene terephthalate, polyesters such as low-melting polyester and polyester elastomer obtained by copolymerizing diol and terephthalic acid / isophthalic acid; Fluororesins; Other spinnable resins, such as a mixture of resins, can be used.

The difference between the melting points of the (A) and (B) component resins is preferably 10 ° C. or more. Thus, if heat treatment is performed at a temperature equal to or higher than the melting point of the low melting point component and lower than the melting point of the high melting point component, the low melting point component of the composite fiber is melted, the high melting point component remains as it is, and the intersection of the fibers is thermally bonded. A heat-bonding nonwoven fabric having a three-dimensional network structure can be formed. In the above, when the melting point is not clear, the melting point means the softening point. The measurement of the softening point conforms to JIS K2530.

Examples of such a combination of the resin components (A) and (B) include, for example, high-density polyethylene polypropylene, low-density polyethylene propylene-ethylene butene-1 crystalline copolymer, high-density polyethylene / polyethylene terephthalate, and nylon 6Z. Nylon 66, low melting point polyester Z polyethylene terephthalate, polypropylene Z polyethylene terephthalate, polyvinylidene fluoride / polyethylene terephthalate, mixture of linear low-density polyethylene and high-density polyethylene Polyethylene terephthalate Etc. can be exemplified.

It is preferable that the thermoplastic conjugate fiber is made of an olefin-based resin or a polyester-based resin, or a combination of both. Examples of such a combination of the (A) and (B) resin components include, for example, high-density polyethylene Z polypropylene, Low-density poly (ethylene propylene) -ethylene butene-1 crystalline copolymer, high-density polyethylene Z polyethylene terephthalate, low-melting polyester / polyethylene terephthalate, polypropylene / Examples include polyethylene terephthalate and linear low-density polyethylene zpolyethylene terephthalate.

The form of the composite fiber is a sheath-core type, an eccentric sheath-core type, a side-by-side type, a multilayer type having three or more layers, a hollow multilayer type, a heterogeneous (non-circular) multilayer type, etc., and the resin components (A) and (B) Among them, a structure in which the low melting point resin component forms at least a part of the fiber surface may be used.

The most preferable combination of the constituent components of the composite fiber and its form is a composite fiber having an eccentric sheath-core structure in which the thermoplastic composite fiber has a highly crystalline polypropylene as a core component and a high-density polyethylene as a sheath component. And it has a spiral crimp. Since a fiber having a spiral crimp has a large storage space per single yarn, a web formed by laminating becomes extremely bulky.

The bulkiness of the tube greatly depends on the number of crimps of the thermoplastic fiber used, and it is particularly preferable that the fiber has a helical crimp of 3 to 20 mountains Z inches (2.54 cm). Here, “3 to 20 inches (2.54 cm)” means that the number of crimps per 1 inch (ie, 2.54 cm) of fiber length is 3 to 20 mountains. . More preferably, it is a fiber having a helical crimp of 5 to 15 mountain inches (2.54 cm), more preferably 5 to 10 mountain inches (2.54 cm). A nonwoven fabric using fibers having a crimp number in this range is very bulky and preferable. If the number of helical crimps is considerably smaller than three ridges (2.54 cm), the bulk of the nonwoven fabric tends to be small, as in the case of straight fibers. On the other hand, when the number of crimps of the spiral type is considerably larger than 20 mountains Z inches (2.54 cm), the bulk of the nonwoven fabric tends to decrease on the contrary because the holding space per single yarn is small. is there.

In the composite fiber, the composite ratio of the low melting point resin component to the high melting point resin component is 10 to 90% by weight for the low melting point resin component and 90 to 10% by weight for the high melting point resin component. It is. More preferably, the low melting point resin component is 30 to 70% by weight, and the high melting point resin component is 70 to 30% by weight. When the low-melting resin component is less than 10% by weight, the heat-bondable nonwoven fabric made of the composite fiber has insufficient tensile strength, and when it exceeds 90% by weight, the core remaining without being melted at the time of thermal bonding is too small. Therefore, the bulk of the heat-bonded nonwoven fabric made of the conjugate fiber tends to be small. When the short fibers are straight, the nonwoven fabric is very uniform, but the bulk is small and very flat, which narrows the range of application and development as a product. . However, it is preferable to use a short fiber having an apparent crimp because a bulky nonwoven fabric can be produced. Examples of the crimped shape of the short fibers used in the short-fiber nonwoven fabric of the present invention include spiral (three-dimensional crimped), zigzag, and wavy shapes. Short fibers having crimps of any of these shapes can be used for the short fiber nonwoven fabric of the present invention, but spiral crimps are most preferred. When the crimped shape of the short fiber is helical, the entanglement between the fibers is small, and the bulk of the obtained nonwoven fabric is extremely large. This tendency becomes more remarkable when the fiber has a fiber length in the preferable range described above and the shape of the spiral becomes closer to a circle.

When the shape of the crimp is zigzag, the larger the number of crimps, the more deeply and neatly the crimp is set, so that the bulk of the obtained nonwoven fabric increases. Since a tendency to become entangled appears, it is difficult to obtain a uniform nonwoven fabric.

When the shape of the crimp is corrugated, the tendency of the fibers to be entangled further becomes remarkable, and a large fiber mass is generated, which easily causes sieving and screen clogging, thereby making it difficult to produce a nonwoven fabric.

However, the effects of the present invention will not be impaired in any of the crimp shapes unless the number of crimps and the fiber length deviate significantly from the preferable ranges described above.

When fabricating a web using a conventional card machine, the fibers are entangled with each other. Because of the pull, the volume of the web becomes smaller. Therefore, as a preferred embodiment of the present invention, a method of not pulling the tube may be considered. For example, there is a method of producing the tube by dropping the fibers. According to the method of dispersing fibers one after another, the fibers are not entangled with each other and pulled, so that the bulkiness of the fibers themselves is not impaired and the bulkiness of the fibers is fully functioned. Nonwoven fabrics can be made.

When fabricating a web by dispersing the fibers and allowing them to accumulate, there is a problem that if the fibers are long, uniform dispersion is difficult, and the nonwoven fabric tends to be coarse and dense. On the other hand, if the fibers are shortened, the fibers are easily dispersed uniformly, and a nonwoven fabric having no unevenness can be produced. Further, as a method of improving the uniform dispersibility of the fiber, there is a method of passing through a screen or a screen. When passing through a screen or screen, even for short fibers, the fibers become entangled with each other before passing through the screen, and the entangled fiber mass passes through the screen and is laminated, resulting in an uneven nonwoven fabric containing fiber mass Sometimes. A nonwoven fabric mixed with a fiber lump may have a rough feeling, or the color of the nonwoven cloth may be uneven due to the subtle reflection characteristics of the fiber lump.

Some short fibers are easily entangled and others are hard to be entangled. When classified, the crimps having a zigzag shape and having a large number of crimps and / or having a large crimp set force tend to be relatively easily entangled. In addition, short fibers with a crimped wavy shape tend to be easily entangled because the ends of the fibers are fishhook-shaped, and short fibers with a crimped spiral shape are located close to the circumference of the same circle. It is particularly preferable because it is difficult to get entangled.

There are two types of fiber clumps that degrade the nonwoven fabric uniformity: those that are entangled with fibers and those that are not fully opened. Since the single yarns are close to each other in the unspread portion and the single yarns are in close contact even after the opening process, it is an effective method to prevent the single yarns from approaching each other. It is. Specifically, the unspread portion can be reduced by selecting the shape of the crimp. The crimped shape is more wavy than the zigzag shape, and more helical than the wavy shape, in which the fibers are easily dispersed and the unspread portion is small. In other words, the occurrence of the entanglement between the fibers and the unopened portion can be suppressed by the shape of the crimp.

In other words, by sieving or passing a short fiber whose crimp shape has been adjusted, the fiber is uniformly dispersed three-dimensionally, and the fiber is deposited to produce a tube. By subjecting the contact points to heat bonding, the object of the present invention of providing a bulky nonwoven fabric having a sufficiently high bulkiness that fibers can contribute to the nonwoven fabric can be achieved.

The nonwoven fabric made by the method of sieving the fiber and passing it through the screen is a three-dimensionally dispersed and piled down fiber, so it is compared to a nonwoven fabric in which the fiber is aligned in one direction by a force machine. Large specific volume. Large specific volume ぃ The nonwoven fabric is particularly suitable for applications that have a soft feeling and directly touch the body, for example, absorbent articles such as disposable diapers and napkins. In addition, a large specific volume means that it is bulky and has a high cushioning property, so it can be used for bandages and eye patches, ranchon mats, cooking utensils, glassware packaging materials, fruits and vegetables, cut flower packaging materials, musical instruments and furniture. It is suitable for use in applications requiring cushioning, such as packaging materials.

The heat-adhesive conjugate fiber used for the short-fiber nonwoven fabric of the present invention can be produced, for example, by the following steps.

Melts the resin of the core and sheath components, for example, from 100 to 35 holes

Discharge from composite spinneret 0. At this time, the undrawn yarn is cooled by air cooling just below the die. Undrawn yarn from 3 denier to 400 denier is produced by drawing at a discharge rate of 100 g / min to 200 g / min and a take-up speed of 40 m / min to 1300 m / min. I do. Not yet The drawn yarn is drawn between the two rolls heated from 60 ° C. to 120 ° C. with the rotation speed of the second roll being higher than the rotation speed of the first roll. By setting the ratio of the rotation speed of the first roll to the rotation speed of the second roll between 1: 2 and 1: 5, a drawn yarn of 1 denier or 100 denier is produced. . After a finishing agent is applied to the drawn yarn with a touch roll, it is passed through a box-type crimping machine to produce a crimped tow. The number of crimps is preferably 0 to 25 peaks per inch. Since the tow contains about 10% by weight of moisture, it is dried at 60 ° C to 120 ° C using a dryer. The dried tow is cut to a fixed fiber length within a fiber length range of 3 mm to 25 mm using a push-to-cut type cutter. Such a fiber length is substantially shorter than the fiber used for the conventional card nonwoven fabric.

Also, when fabricating non-woven fabric, use multiple forming heads and use different fineness or different crimped short fibers in each forming part to have density gradient in the thickness direction. Nonwoven fabric can be produced. The nonwoven fabric having a density gradient in the thickness direction manufactured in this way can be used as a nonwoven fabric material for filters such as liquid filters and air filters.

The short-fiber nonwoven fabric produced as described above can be used as an absorbent article, such as a disposable diaper, as a surface nonwoven fabric, a second sheet, or a backing sheet. In particular, since the short fiber nonwoven fabric is bulky, it is suitable as a second sheet requiring bulkiness. Further, a nonwoven fabric obtained by mixing pulp, heat-fusible fibers and a high water-absorbing material is suitable as an absorber that does not lose its shape during urine absorption. The short-fiber nonwoven fabric of the present invention can be produced as follows using short fibers having a fiber length of 3 to 25 mm using an air-laid apparatus.

Air raid device 1 has an opening only on the lower surface as shown in Figs.

0 A casing 2 having a trapezoidal cross section, fiber inlets 3 and 4 provided at both ends of the casing 2, respectively, facing the inlets 3 and 4, and being parallel to a side surface of the casing 2. The web forming heads 5 and 6 made of rotatable cylindrical screens 5a and 6a are provided so as to be in sliding contact with the inner walls of the cylindrical screens 5a and 6a, respectively. Fiber circulating zones 7 provided between both end portions of the provided needle rolls 5b and 6b and the cylindrical screens 5a and 6a, and both end surfaces of the casing 2 respectively. And 8 mainly. A net conveyor 9a is provided directly below the lower surface of the arrayed device 1, and a pair of drive rolls 17a and 17b and a suction device 10 are attached to the net conveyor 9a. I have. Further, as an apparatus for the next step, a suction dryer 12 for thermally bonding the composite fibers constituting the web and a net conveyor 19b for passing the web here are attached, and below the net conveyor 19b. A pair of drive rolls 17c17d for moving the conveyor 9b is provided, and a compression roll 11 is provided on the drive roll 17c with the net conveyor 19b interposed therebetween. Further, a feed roll 18 for feeding the produced heat-bondable nonwoven fabric 14 and a pair of drive rolls 19 a and 19 b for driving the take-up roll 14 are provided. In the above apparatus, the short fibers are sent to a cotton feeding circulation duct communicating with the fiber inlets 3 and 4 after the fibers are opened mechanically by a weaving machine (not shown). At this point, the fiber bunching is almost completely unwound. The fibers 15 fed into the fiber inlets 3 and 4 pass through the passage formed by the cylindrical screens 5a and 6a and the fiber circulation zones 7 and 8 by arrows C1, C2 and C2 in FIG. While being moved in the directions of C 3 and C 4 and in the directions of arrows D l, D 2, D 3 and D 4, they are mixed and circulated. As shown in Fig. 3, the circulated fibers are used as needle rolls 5b and 6b that rotate in the direction of arrow AA 'and a cylindrical screen that rotates in the direction of arrow BB'. Due to the centrifugal force and shearing action that occurs in both rotations of 5a and 6a, it is discharged through the rotating cylindrical screens 5a and 6a. The discharged fiber is sucked from below the casing 2 by the suction device 10 and collected at the upper portion of the net conveyor 19a. The collected paper 16 is compressed between the web compression roll 11 and the driving roll 17c of the net conveyor 19b. The fibers collected at this point are oriented in random directions to form webs.

The web 16 is compressed by a web compression roll 11 and then supplied to a suction dryer 12 where the melting point is higher than the low melting point component and lower than the high melting point component, for example, from 90 ° C to 170 ° C. By performing the heat treatment at a temperature of ° C for 3 to 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 a three-dimensional net peak. The heat-bonding non-woven fabric 13 of the structure is formed and wound on the winding roll 14.

In order to arrange the short fibers conveyed by air more randomly, a method of passing through a sieve or a net made of various meshes may be used as a manufacturing method, and specifically, a method of passing through a screen. It is preferable to use a method of dispersing and accumulating the particles by making them fall.

The shape of the holes in the cylindrical screens 5a and 6a used for the air-laid device are usually horizontally long rectangles, but the vertical length is l ~ 3mm and the horizontal length is 15 ~ A 3 O mm rectangle is preferred. The shape of the hole may be a circle, a triangle, a rectangle, a polygon, an ellipse, or the like in addition to a horizontally long rectangle. The screen porosity is preferably 20% to 50%. By selecting such a hole diameter and an opening ratio, a uniform tube can be manufactured.

Among the short-fiber nonwoven fabrics of the present invention, the nonwoven fabrics composed of the heat-adhesive conjugate fibers are heat-sealed at the intersections of the fibers by heat treatment with a suction dryer 112 after forming the web. This heat treatment is performed by a suction dryer 1 In place of 2, the heating may be performed using a heating device such as a heat calender roll. The basis weight of the obtained nonwoven fabric is not particularly limited, but is preferably about 10 to 1000 g / m ² . About 1 0~60 gZm ² For diapers surface material, about 10~500 gZm ² For wiper, about 10 when the filter; I 00 0 g / m ² is preferred. The apparent density of the non-woven fabric is not particularly limited, and is preferably about 0.017 to 0.10 g / cm ³ in consideration of force and 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 heat-bonding nonwoven fabric of the short-fiber nonwoven fabric of the present invention preferably has a thermocompression bonding area ratio of 10 to 30% when a heat calender roll is used to thermally fuse intersections of fibers. By setting the pressure-bonding area ratio in this range, it is preferable since a nonwoven fabric having excellent thread removal resistance and excellent nonwoven fabric strength and a soft feeling can be easily obtained.

The short-fiber nonwoven fabric of the present invention can be used for various applications either alone or by lamination, sewing, heat fusion, and the like with other members. For example, when used as a member of pants-type disposable diapers, it can be used for parts that require both texture and strength, such as surface materials and back sheets. Of course, when used for the diaper or the like, it can be used in combination with other members, such as an elastic member for tightly attaching the trunk and the legs, or the thermo-adhesive nonwoven fabric. Further, the heat-bondable nonwoven fabric can be laminated with other nonwoven fabrics, tissue papers, webs, films and the like, and used as a cover material for the front surface material ゃ a cover material for the back surface material.

The short-fiber nonwoven fabric of the present invention can be used for wipers of furniture, cars, etc. by adhering various lubricants and the like.

In addition, the short fiber nonwoven fabric is folded or formed into a cylindrical shape, the thermoadhesive nonwoven fabric is wound into a tubular shape, or the thermoadhesive nonwoven fabric is rolled while being heated, and the layer is heated. Post-processing such as molding into a fused cylinder and filter media can do. Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

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 specific volume of the short-fiber nonwoven fabric in Table 1 was defined as follows and measured.

(1) Specific volume

The basis weight and thickness of the nonwoven fabric were measured, and the calculated value was used as the value of the specific volume.

Specific volume-(Y l O O x l O O) / X

Here, X represents the basis weight (gZm ² ) of the nonwoven fabric, and Y represents the thickness (cm) of the nonwoven fabric.

The size of the nonwoven fabric sample was 25 cm in length and 25 cm in width, and the number of fiber masses of the short fiber nonwoven fabric in Table 1 was defined as follows and measured.

(2) Number of fiber mass

In the nonwoven fabric 2 0 g, the number of volume l mm ³ or more fibrous mass and the number of fiber masses

Ah¾ o

However, 20 g of the nonwoven fabric was sampled at 10 places, and the average value of the number of fiber clumps observed in each sample was defined as the number of fiber clumps.

(3) Hand of non-woven fabric

Five panelists evaluated the uniformity of the nonwoven fabric, the presence or absence of roughness, and the uniformity of the hue of the nonwoven fabric (the hue becomes uneven due to the fiber mass). Poor head when three or more panelists rate the nonwoven fabric as uneven, grainy, or non-uniform in color And good texture at other times

Four It was determined.

(Example 1)

A method in which rayon staple fibers are mixed with thermo-adhesive fibers, and the intersections of the fibers are bonded by heat treatment to form a nonwoven fabric.

Number of crimps 12 With a zigzag crimp of 2.5 ridges / inch (2.54 cm), a thickness of 1.5 dZf and a length of 5 mm (hereinafter referred to as 1.5 dZ fx 5 mm) It has a 40-weight rayon fiber with a core of polypropylene and a high-density polyethylene sheath, and has a spiral crimp of 7 crimps and 7 inches (2.54 cm). 60% by weight of eccentric sheath-core composite fiber with dZfX of 5 mm was put into and passed through the opening machine, and the fiber was opened mechanically, and then supplied to the air-laid apparatus shown in Figs. 1 to 3 for processing. . That is, the rayon fiber and the heat-fused fiber 15 passed through the opening machine are fed to the fiber feed ports 3 and 4 via the cotton feeding circulation duct, and the rotating cylindrical screens 5a and 6a are rotated. The fiber was discharged from. The discharged fibers were collected by a net conveyor 19a of a suction device 10 operated at 9 Om / min, and a web 16 was produced. After being compressed with a web compression roll 11, it is heat-treated at 150 ° C for 3 seconds using a suction dryer 12 to melt and bond the high-density polyethylene of the sheath component to form the nonwoven fabric 13. It was prepared and wound on a take-up roll 14.

The physical properties of the obtained nonwoven fabric were a basis weight of 25 gZm ² , a thickness of 3.6 mm, a specific volume of 144 cm ³ Zg, and a number of fiber clumps of 2.1 / "20 g. The results are shown in Table 1. (Example 2)

A method for producing heat-fusible short fibers.

Five MFR (melt flow rate) = ll gZ10 min (JISK7210 condition 14) as the core component Highly crystalline polypropylene with Ml (menolein index) = 16.5 gZ10 min (JISK7210 condition 4) as the sheath component ) Is spun from an eccentric sheath-core composite spinneret with a discharge ratio of 5: 5 and an eccentric sheath-core composite spinneret with 621 holes at a discharge rate of 450 gZin, and is drawn at a take-up speed of 592 mZm in to produce 11 denier undrawn yarn. Was prepared. At the time of spinning, the yarn was cooled by air cooling just below the spinneret, and a finishing agent containing lauryl phosphate potassium salt as a main component was applied with evening roll.

The temperature of the first roll is 90 ° C, the temperature of the second roll is 20 ° C, and the rotational speed ratio of the first roll to the second roll is 1: 4. Stretching was performed between two rolls set at 5, to produce a drawn yarn having a helical crimp of 3 denier. The drawn yarn having the helical crimp was cut by using a push-off type force cutter to produce a fiber having a fiber length of 5 mm.

Hereinafter, a nonwoven fabric manufacturing method using the heat-fusible fiber will be described.

The composite fiber was passed through a weaving machine, mechanically opened the fiber, and then supplied to an air-laid apparatus shown in Figs. 1 to 5 for processing. That is, the opened composite fiber 18 was fed into the fiber inlets 3 and 4 via the cotton circulation duct, and the fibers were discharged from the rotating cylindrical screens 5a and 6a. The discharged fibers were collected by a net conveyor 9a having a suction device 10 operating at 9 Om / min to produce a web 16. After compression with the web compression port 11 1, heat treatment at 150 ° C for 3 seconds using a suction dryer 12 to melt-bond the high-density polyethylene of the sheath component to produce a nonwoven fabric 13. It was wound on a take-up roll 14. The physical properties of the obtained nonwoven fabric were as follows: basis weight 25 gZm ² , thickness 4.6 mm, The volume was 18.5 cm ³ Zg, and the number of fiber masses was 1.2 pieces / 20 g. Table 1 shows the results.

(Example 3)

A nonwoven fabric was produced under the same conditions as in Example 2 except that the fiber length of the conjugate fiber was set to 1 Omm.

Physical properties of the obtained nonwoven fabric were a basis weight of 25 g / m ² , a thickness of 4.4 mm, a specific volume of 176 cm ³ Zg, and a number of fiber masses of 1.9 Z20 g. Table 1 shows the results.

(Example 4)

A nonwoven fabric was produced under the same conditions as in Example 2 except that the fiber length of the conjugate fiber was changed to 15 mm.

Physical properties of the obtained nonwoven fabric were a basis weight of 25 gZm ² , a thickness of 4.25 mm, a specific volume of 170 cm ³ Zg, and a number of fiber masses of 3.8 Z20 g. Table 1 shows the results.

(Example 5)

A method for producing a nonwoven fabric using polyester short fibers and parallel type composite fibers. Number of crimps 14 Parallel type consisting of 30% by weight of 2 d / f X 5 mm polyester fiber having a zigzag crimp of 14 inches (2.54 cm), polypropylene component and high density polyethylene component 70% by weight of a 2 d / fx 5 mm conjugate fiber having a helical crimp of 6 crimps / inch (2.54 cm), which is a conjugate fiber, is fed into the opening machine and passed therethrough. After mechanically weaving the fibers, they were fed to the air-laid apparatus shown in Figs. In other words, the opened polyester fiber and the parallel type composite fiber 15 Then, the fibers were fed into fiber inlets 3 and 4 and the fibers were discharged from the rotating cylindrical screens 5a and 6a. The discharged fibers were collected by a net conveyor 19a having a suction device 10 operated at 9 OmZmin to produce a web 16. After compressing this tube with a tube compression roll 11, use a suction drier 12 to 150. By heat-treating with C for 3 seconds, the high-density polyethylene of the sheath component was melt-bonded to produce a nonwoven fabric 13, which was taken up on a take-up roll 14.

Physical properties of the obtained nonwoven fabric were a basis weight of 25 gZm ² , a thickness of 3.4 mm, a specific volume of 13.7 cm ³ / g, and a number of fiber masses of 2.2 pieces Z20 g. Table 1 shows the results.

(Example 6)

A method for producing heat-fusible short fibers.

MFR = ll gZ1 0 minutes High crystalline polypropylene with JISK 72 10 conditions 14) and high density polyethylene with MI = 16.5 gZ1 0 minutes (JISK 72 10 conditions 4) Hole at discharge ratio 5: 5 Except that an undrawn yarn of 8.1 denier was produced by spinning at a discharge rate of 450 g / min and using a take-up speed of 592 mZmin using a parallel composite spinneret of number 62 1 The other conditions were the same as in Example 2 to produce a nonwoven fabric.

The properties of the obtained nonwoven fabric, the basis weight 25 gZm ^2, thickness 4. 5 mm, the specific volume 1 8 1 cm ³ Zg, was the number 1.3 pieces / ^/ 2 0 g of fiber masses. Table 1 shows the results. (Example 7)

The number of holes in the spinneret is 60, the discharge rate during spinning is 200 g / min, Example 6 was the same as Example 6 except that the take-up speed was 4 17 mZm in, the undrawn yarn of 72 denier, the drawn yarn of 18 denier, and the number of spiral crimps was 6 mountains Z inches (2.54 cm). Fibers were produced under the same conditions.

The conditions for producing the nonwoven fabric were the same as in Example 5.

The properties of the obtained nonwoven fabric having a basis weight 2 5 gZm ", thickness 3. 9 mm, specific volume 1 56 cm ³ Zg, the number of fiber masses 0.5 cells /" was 2 0 g. Table 1 shows the results.

(Example 8)

A method for producing heat-fusible short fibers.

MFR = 16 gZl 0 min as the core component (JISK7210 condition 14) polypropylene and MI = 16.52 10 min as the sheath component () 1 SK7210 condition 4) high density polyethylene at a discharge ratio of 5 to 5. Using a sheath-core composite spinneret with 621 holes, spinning was performed at a discharge rate of 450 g / min, and drawing was performed at a take-up speed of 919 mZmin, thereby producing 7.1-denier undrawn yarn. During spinning, the yarn was cooled by air cooling just below the spinneret.

The unstretched yarn is stretched between two rolls heated to 90 ^DC each by setting the rotation speed ratio of the first roll and the second roll to 1: 4, and the 2 denier stretched yarn is formed. Produced. After applying a finishing agent containing lauryl phosphate potassium salt as a main component to the drawn yarn using evening rolls, the yarn is passed through a box-type crimping machine to form a tow having 14 zigzag crimps per inch. Produced.

Since the tow contained moisture, it was dried at 90 ° C using a dryer, and then cut using a push-cut type cutlet to produce a fiber with a fiber length of 10 mm.

9 T 7

The conditions for producing the nonwoven fabric were the same as in Example 5.

The physical properties of the obtained nonwoven fabric were a basis weight of 25 g / m ² , a thickness of 2.8 mm, a specific volume of 79 cm ³ Zg, and the number of fiber masses 4.5 Z 20 g. Table 1 shows the results.

(Example 9)

A method for producing short fibers of heat-sealed fibers.

By drawing the spinneret with 60 holes, a discharge rate of 200 gZmin, and a take-up speed of 26 3 m / min, an undrawn yarn of 114 denier is made and a drawn yarn of 32 denier is made. did. A heat-fusible conjugate fiber was produced under the same conditions as in Example 8, except that 12 zig-zag crimps were applied per inch and the fiber length was set to 1 Omm.

The conditions for producing the nonwoven fabric were the same as in Example 5.

Physical properties of the obtained nonwoven fabric were a basis weight of 25 g / m ² , a thickness of 2.6 mm, a specific volume of 45 cm ³ / g, and the number of fiber masses was 3.6 g / 20 g. Table 1 shows the results.

(Example 10)

Using a spinneret with 100 holes, the discharge rate during spinning is 200 g / min, the yarn is water-cooled during spinning, and the drawing speed is 53 mXmin. A fiber was produced under the same conditions as in Example 8 except that the yarn, 100 denier drawn yarn, 10 zigzag crimps per inch, and a fiber length of 25 mm were used.

The conditions for producing the nonwoven fabric were the same as in Example 5.

Physical properties of the obtained nonwoven fabric were a basis weight of 25 gZm ² , a thickness of 2.65 mm, a specific volume of 58 cm ° / g, and a number of fiber masses of 2.4 pieces Z0 g. result Are shown in Table 1.

(Example 11)

A method for producing short fibers of heat-sealed fibers.

Discharge ratio of high crystalline polypropylene with MFR = 1 1 g / 10 min (JISK7210 condition 14) as core component and high density polyethylene of MI-16.5 gXl 0 min (JISK7210 condition 4) as sheath component A 5-denier undrawn yarn was produced by spinning at a discharge rate of 350 g / min and a take-up speed of 995 mZmin using a sheath-core composite spinneret having 5 to 5 holes and 621 holes. During spinning, the yarn was cooled by air cooling just below the spinneret.

For the undrawn yarn, the first roll temperature was set to 90 ° C, the second roll temperature was set to 20 ° C, and the rotation speed ratio of the first roll to the second roll was 1: 1. 4. Stretched between two rolls set at 5. After applying a finishing agent containing lauryl phosphate potassium salt as the main component to this drawn yarn with Tytrol, it is passed through a box-type crimping machine to produce 9 wavy ridges per inch (2.54 cm). A tow having a crimp was produced. The drawn yarn having the wavy crimp was cut using a push-cut type cutter to produce a fiber having a fiber length of 5 mm.

The conditions for producing the nonwoven fabric were the same as in Example 5.

The physical properties of the obtained nonwoven fabric were 23 g in weight, 3.75 mm in thickness, specific volume of 163 cm ³ / g, and 18 pieces of fiber mass Z20 g. Table 1 shows the results.

(Example 12)

A method for producing heat-fusible short fibers. Polypropylene with MFR = 10 g / 10 min (JISK 721 0 condition 14) and polypropylene with MFR = 23 gZ 10 min (JISK 721 0 condition 14) Dispensing ratio 5: 5 Parallel type composite spinneret with 350 holes Spinning was performed using gold at a discharge rate of 200 g / min, and drawing was performed at a drawing speed of 635 mZ min to produce an undrawn yarn of 8.1 denier. At the time of spinning, the yarn was cooled by air cooling just below the spinneret, and a finishing agent mainly composed of lauryl phosphate potassium salt was applied with tatty roll. For the undrawn yarn, the first roll temperature was set to 90 ° C, the second roll temperature was set to 20 ° C, and the rotation speed ratio of the first roll to the second roll was 1: 1. The film was drawn between two rolls set to 4.5 to produce a drawn yarn having a spiral crimp of 2 denier. The extended drawn yarn having the helical crimp was cut using a push-cut type cutter to produce a fiber having a fiber length of 1 Omm.

The nonwoven fabric was produced under the same conditions as in Example 5.

Physical properties of the obtained nonwoven fabric were a basis weight of 25 gZm ² , a thickness of 3.25 mm, a specific volume of 130 cm ³ Zg, and a number of fiber masses of 1.4 pieces 20 g. Table 1 shows the results.

(Example 13)

A method for producing heat-fusible short fibers.

Crystalline polyethylene terephthalate with intrinsic viscosity of 0.68 d1 Zg as the core component, and high-density polyethylene with M1 = 16.5 gZ10 min (JISK 7210 condition 4) as the sheath component at a discharge ratio of 5 to 5. Using a sheath-core type composite spinneret with 621 holes, spinning was performed at a discharge rate of 450 gZmin, and drawing was performed at a drawing speed of 1035 mZmin to produce an undrawn yarn of 6,3 denier. During spinning, the yarn is cooled by air cooling just below the spinneret. Rejected.

The undrawn yarn was drawn between two rolls each heated to 90 ° C. with the rotation speed ratio of the first roll and the second roll set to 1: 3.3. After applying a finishing agent containing lauryl phosphate potassium salt as a main component to the drawn yarn with evening rolls, the yarn is passed through a box-type crimping machine to form a wavy crimp of 5 peaks per inch (2.54 cm). Was produced. The drawn yarn having the wavy crimp was cut using a push-type cutter to produce a fiber having a fiber length of 1 Omm.

The conditions for producing the nonwoven fabric were the same as in Example 5.

Physical properties of the obtained nonwoven fabric were a basis weight of 25 gZm ² , a thickness of 3.0 mm, a specific volume of 101 cm ³ Zg, and a number of fiber masses of 2.6 pieces / 20 g. Table 1 shows the results.

(Comparative Example 1)

A nonwoven fabric was produced under the same conditions as in Example 2 except that the fiber length was 38 mm and a carding machine was used during the production of the web.

The physical properties of the obtained nonwoven fabric were a basis weight of 25 gZm ² , a thickness of 0.9 mm, a specific volume of 36 cm ³ Zg, and the number of fiber masses was 0.9 / 20 g.

Since it was a card nonwoven fabric, the nonwoven fabric had a smaller specific volume than the other examples.

Table 1 shows the results.

(Comparative Example 2)

A nonwoven fabric was produced under the same conditions as in Example 2 except that the fiber length was 30 mm.

The physical properties of the obtained nonwoven fabric are as follows: basis weight 25 g / n ^, thickness 2.75 mm, The specific volume was 110 cm ³ Z g and the number of fiber mass was 8.5 Z 20 g. Although it is an airlaid nonwoven fabric, since the fiber length is longer than 25 mm, the fibers are easily entangled and the nonwoven fabric has a large number of fiber clumps. Therefore, the obtained non-woven fabric was poor in uniformity, had a feeling of graininess, noticeable white portions due to fiber mass, and non-uniform hue. Therefore, this nonwoven fabric was judged to have a poor texture. The results are shown in Table 1.

(Example 14)

A commercially available disposable diaper having a substantially I-shaped planar cross section substantially similar to that of a railroad rail was used, and only the surface material of the disposable diaper was substantially replaced with the heat-adhesive nonwoven fabric described in Example 2.

The commercially available disposable diaper uses a polyethylene / polypropylene-based heat-fusible composite fiber staple, and has a surface material of a non-woven fabric in which intersections of the fibers are heat-sealed, and a water-absorbing material mainly composed of pulp and a highly water-absorbent resin. , And a diaper with 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 3 was laminated on the same portion instead of the cut and removed surface material. Further, the heat-bonding nonwoven fabric and the nonwoven fabric near the remaining leg portions were heat-sealed. Excess heat-bondable nonwoven fabric was cut off with scissors and removed to obtain a disposable diaper on which a heat-fusible nonwoven fabric was provided as a surface material. The diaper had a large strength in the lateral direction (in the longitudinal direction) of the surface material, a bulky and soft texture, and was suitable as a paper diaper. \ SB ÷ *-レレ鋤 * i * n a 維 ft aft a a ft df mm cm3 / g pcs Z20g Shape (mountain / 2.54cm) Difficult 1 3 5 143 2. 1 spiral 7 good

1.5 5 zigzag 12 example 2 3 5 185 1.2 spiral 7 good example 3 3 10 176 1.9 spiral 8 good starvation 4 3 15 170 3.8 spiral 7 good

H example 5 2 5 137 2.2 spiral 6 good

2 5 zigzag 14 example 6 2 5 181 1.3 spiral 7 good example 7 18 5 156 0.5 0.5 spiral 6 good example 8 2 10 79 4.5 zigzag 14 good example 9 32 3 45 3.6 zigzag 12 Good example 10 100 25 58 2.4 Zigzag 10 Good Difficult example 11 1.5 5 163 1.8 Wave 9 Good Example 12 2 10 130 1.4 Spiral 8 Good example 13 2 10 101 2.6 Zigzag 5 Good example 1 3 38 36 0.9 spiral 7 good m 2 3 30 110 8.5 spiral 7 bad As is clear from the results in Table 1, the configuration of the denier, the fiber length, the crimped shape, and the number of crimps according to the present invention allows the fiber to sufficiently function to contribute to the bulkiness, and the bulky fiber mass A good nonwoven fabric with a small texture was obtained. 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 nonwoven fabric by the card method, the number of fibers increases, so that the dispersion of fibers becomes less dense and dense, and a uniform nonwoven fabric is obtained. Was done. Furthermore, since the non-woven fabric is formed by dispersing the fibers and being deposited, the density and the air permeability are lower than those of the card nonwoven fabric in which the fibers are hooked and oriented. The short-fiber nonwoven fabric of the present invention is formed by dispersing and depositing short fibers using short fibers to form a nonwoven fabric, so that the nonwoven fabric obtained by the force method is hindered in bulkiness by pulling the fibers. Thus, a bulky and soft nonwoven fabric can be obtained.

In addition, since the short fiber nonwoven fabric of the present invention has a shorter fiber length than the card method nonwoven fabric, it is laminated in a randomly dispersed state, so that unevenness in the density of fibers is reduced and a uniform nonwoven fabric is obtained. Furthermore, since the nonwoven fabric is formed by dispersing the fibers in a three-dimensional direction and accumulating them, the density is lower than that of the card nonwoven fabric in which the fibers are hooked and oriented. Are better. Industrial applicability

Due to the above effects, the nonwoven fabric of the present invention is suitably used for applications that have a soft feeling and directly touch the body, for example, absorbent articles such as disposable diapers, napkins, incontinence pads, and breast milk pads. In addition, it has a large specific volume, is bulky and has good cushioning properties, so it can be used for bandages, eyeglasses, luncheon mats, cooking dishes, glassware packaging, fruits and vegetables, cut flowers, musical instruments and furniture. It is suitably used for applications that require buffering properties. In addition, a non-woven fabric base having a non-woven fabric having a density gradient in the thickness direction can be used as a non-woven fabric material for filters such as liquid filters and air filters.

Claims

The scope of the claims

1. One or more types of short fibers having a fiber length of 3 to 25 mm and a single fiber fineness of 1 to 100 denier are dispersed and deposited, and the intersection of the short fibers is A bonded nonwoven fabric, wherein the specific volume of the nonwoven fabric is 40 to 200 ε ιη ^ϋ Ζ8, and the number of fiber lumps having a volume of lmm ″ or more composed of the short fibers present in the nonwoven fabric is Short-fiber non-woven fabric with 5 or less per 20 g non-woven fabric.

2. The short-fiber nonwoven fabric according to claim 1, wherein the short fiber has a fiber length of 5 to 1 Omm.

3. At least one of the short fibers has a crimp count of 3 to 20 mountains Z inches (2.5

2. The short-fiber nonwoven fabric according to claim 1, which is a short fiber having a helical crimp of 4 cm).

4. The short-fiber nonwoven fabric according to claim 1, wherein at least one of the short fibers is a thermoplastic fiber.

5. The short-fiber nonwoven fabric according to claim 1, wherein at least one of the short fibers is an olefin- or polyester-based thermoplastic short fiber.

6. The short-fiber nonwoven fabric according to claim 1, wherein at least one of the short fibers is a thermoplastic conjugate short fiber containing a heat-fusible component as one component in the fiber.

7. Claim 1 wherein at least one of the short fibers is a short fiber having an eccentric sheath-core structure having a core component of highly crystalline polypropylene and a sheath component of high-density polyethylene. Short fiber non-woven fabric.

8. An absorbent article using the short-fiber nonwoven fabric according to any one of claims 1 to 7.