JPH11131346A - Low-modulus wet-type nonwoven fabric and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide thin, low-modulus wet-type nonwoven fabric that has a low modulus and excellent fitting properties and shows reduced bleeding from the back face. SOLUTION: This low-modulus wet-type nonwoven fabric comprises 50-99 wt.% of tangibly crimped fibers having a filament diameter of 10-20 μm, filament length of 7-15 mm, crimp number of 6-20/inch and 1-5 wt.% of extremely thin fibers having an aspect ratio of 1,000-1,500 and a smaller fiber diameter than that of the tangibly crimped fibers. These fibers are homogeneously mixed and mutually interlaced three-dimensional, not fused between filaments and has a modulus of <=1.0 N/cm at 10% elongation in at least one direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a low modulus wet nonwoven fabric. More specifically, the present invention relates to a low-modulus wet nonwoven fabric which is effective as a base material of a transdermal mouthpiece (a base material for a poultice) or a support base material of a gel for heat cooling.

[0002]

2. Description of the Related Art As a poultice base fabric, a non-woven fabric having a low modulus is used, and a fabric obtained by a needle punch method has been most commonly used. Not only the pulp base fabric but also a low-modulus nonwoven fabric is required to be reduced in weight and thickness. These needle-punched nonwovens have low modulus,
Although the fit is good, only low needling can be performed to maintain low modulus, so that the obtained nonwoven fabric has a problem that it becomes bulky. Further, the web obtained by the card method has a large basis weight unevenness, and when a percutaneous mouthwash or the like is applied, the non-woven fabric with a low basis weight is stained on the opposite surface, making it difficult to lower the basis weight, and is bulky. It had to be something.

As an alternative to needle punching, a method has been proposed in which fibers are entangled by a high-pressure water flow. In the hydroentanglement method, since the web is suppressed, a thin nonwoven fabric can be obtained as compared with the needle punch method, but there is a problem that the modulus becomes high.

As an improvement over these points, Japanese Patent Publication No. 8-19611 proposes a light-weight, low-modulus nonwoven fabric which is entangled with water and contains side-by-side crimped fibers.

[0005] However, this nonwoven fabric also uses a web manufactured by a dry method, and has a large basis weight unevenness.
If the basis weight is low, there is a possibility that the drug solution oozes from the back surface when the drug or gel is actually applied.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems and provides a low-modulus wet nonwoven fabric which is not only low in modulus and excellent in fitting property but also has little bleeding from the back surface. It is intended to do so.

[0007]

Means for Solving the Problems The present inventors have intensively studied to solve the above problems. As a result, they have found that a nonwoven fabric three-dimensionally entangled with a high-pressure columnar water stream can solve the above-mentioned problem after mixing a microfiber with a fiber having a specific apparent crimp by a specific method. The present invention has been achieved based on these findings.

That is, the present invention provides a fiber having a diameter of 10 to 20 μm.
50 to 99% by weight of an apparent crimped fiber having a fiber length of 7 to 15 mm and a crimp number of 6 to 20 / inch, and an aspect ratio of 100
0 to 1500, containing 1 to 50% by weight of ultrafine fibers having a fiber diameter smaller than that of the actual crimped fibers, uniformly mixed and three-dimensionally entangled with each other, and the fibers are fused. And a 10% modulus in at least one direction is 1.
This is a low modulus wet nonwoven fabric having a modulus of 0 N / cm or less.

The fiber diameter is 10 to 20 μm and the fiber length is 7 to
15 mm, 50 to 99% by weight of actual crimped fibers having 6 to 20 crimps / inch, aspect ratio of 1000 to 1500
In the ultra-fine fibers having a smaller fiber diameter than the actual crimped fibers,
50% by weight, at least a portion of the actual crimped fibers have latent crimpability, they are uniformly mixed and three-dimensionally entangled with each other, and the fibers are not fused,
10% modulus in at least one direction is 1.0 N / cm
The following is a low modulus wet nonwoven fabric.

[0010] Further, a low modulus wet nonwoven fabric having ultrafine fibers having a fiber diameter of 2 to 8 µm is preferred.

In the method for producing a low-modulus wet nonwoven fabric according to the present invention, the apparently-crimped fiber fibers and the ultrafine fibers are uniformly mixed in water to form a papermaking web, which is then loaded on a porous support, and then subjected to a high-pressure columnar process. Inject the water flow, from the obtained confounding web,
It is characterized by removing water.

In the method for producing a low-modulus wet nonwoven fabric according to the present invention, the apparently-crimped fiber containing the fiber having latent crimpability and the ultrafine fiber are uniformly mixed in water to form a web, and then the porous support is formed. The present invention is characterized in that it is loaded on a body and a high-pressure columnar water jet is jetted, and latent crimps are developed while or after removing water from the obtained entangled web.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a low modulus wet nonwoven fabric of the present invention will be described in detail. The low-modulus wet nonwoven fabric of the present invention is not only low-modulus and excellent in fitting property, but also has little oozing from the back surface, and does not show fluff or pills that pose a practical problem.

The modulus described in the present invention means the stress when the nonwoven fabric is stretched at a specific ratio, and the low modulus means that the modulus is low. The 10% modulus is the stress when elongating 10%.

Next, the materials constituting the low modulus wet nonwoven fabric of the present invention will be described. The term “expanded crimp fiber” used in the present invention is used to keep the nonwoven fabric at a low modulus and develop fit. In order to exhibit these performances in a wet nonwoven fabric, it is preferable to use a specific fiber diameter, fiber length, number of crimps and crimp width. Specifically, it is preferable that the fiber has a fiber diameter of 10 to 20 μm, a fiber length of 7 to 15 mm, and a number of crimps of 6 to 20 / inch, which has an apparent crimpability.

If the fiber diameter is smaller than 10 μm, the nonwoven fabric becomes dense and the fit is poor, which is not preferable.
When it is larger than 20 μm, not only the touch of the nonwoven fabric is lowered but also the fluff becomes noticeable, which is not preferable.

If the fiber length is smaller than 7 mm, it is difficult to entangle the fibers, and the fibers fall off the nonwoven fabric. When it is larger than 15 mm, the confounding becomes strong and the modulus becomes large, which is not preferable.

If the number of crimps is less than 6, a low modulus nonwoven fabric cannot be obtained. If it is larger than 20, it is difficult to uniformly disperse the fibers in the papermaking process, and the obtained nonwoven fabric is not preferable because unevenness in the basis weight is increased.

The ultrafine fibers used in the present invention can be mixed with fibers having an apparent crimpability to improve the feel of the nonwoven fabric without impairing the properties of the low-mojurous nonwoven fabric. In addition, since the ultrafine fibers uniformly enter between the fibers having the apparent crimpability, and the fiber network becomes fine,
It is possible to prevent bleeding to the opposite side of the nonwoven fabric, for example, when a chemical is applied to the nonwoven fabric. Further, it is difficult to uniformly disperse only the fiber having the actual crimpability, which is difficult to disperse. However, by mixing the ultrafine fibers, the dispersibility is improved, the formation is not good, and the obtained web (wet paper) ) Is increased, the releasability from a wire or felt is improved, and the papermaking property is improved. Specifically, it is preferable that the ultrafine fibers have a fiber diameter in the range of 1 to 7 μm. If the thickness is smaller than 1 μm, the nonwoven fabric becomes too dense and the modulus becomes high, which is not preferable. If it is larger than 7 μm, the effect of mixing becomes small, which is not preferable.

The fiber length is preferably in the range of 2 to 10 mm. If it is smaller than 2 mm, the entanglement is too weak, and it is not preferable because it is dropped from the nonwoven fabric. If it is larger than 10 mm, it is not preferable that the fibers are entangled so as not to fall off, because the modulus becomes high.

It is preferable that the apparent crimped fiber occupy in the low modulus wet nonwoven fabric is in the range of 50 to 99% by weight and the fine fiber is in the range of 1 to 50% by weight based on the weight of the nonwoven fabric. If the apparent crimped fiber content is less than 50% by weight, the modulus of the nonwoven fabric increases, and if it is more than 99% by weight, not only the formation of the nonwoven fabric deteriorates, but also the peeling from the papermaking wire or wet felt deteriorates, resulting in a uniform nonwoven fabric. Is not preferred since When the ultrafine fibers are less than 1% by weight, not only the formation of the nonwoven fabric is deteriorated, but also the peeling from the papermaking wire or the wet felt becomes poor, and a uniform nonwoven fabric cannot be obtained. 50
If the amount is larger than the weight percentage, the nonwoven fabric becomes dense, the modulus becomes large, and the fitting property decreases, which is not preferable.

The ultrafine fibers and the apparent crimped fibers used in the present invention include polyester fibers such as polyethylene terephthalate, polybutylene terephthalate and copolymers thereof, polyolefin fibers such as polyethylene, polypropylene and polystyrene, polyacrylonitrile and modacrylic. Acrylic fiber, nylon 6, etc.
Polyamide fibers such as nylon 66 and nylon 12, polyvinyl alcohol fibers, synthetic fibers such as polyvinylidene chloride fibers, polyvinyl chloride fibers, and urethane fibers; semi-synthetic fibers such as triacetate fibers and diacetate fibers; viscose rayon; copper ammonia Preferred are regenerated cellulose fibers such as rayon, polynosic rayon, and lyocell, and regenerated fibers obtained by spinning a solution of collagen, alginic acid, chitin, or the like. The polymer constituting these fibers can be used in the form of a homopolymer, a modified polymer, a blend, a copolymer, or the like. As a matter of course, a composite fiber made of a plurality of these materials may be used.

Further, these fibers are water-absorbing, hygroscopic,
It may have a function such as antibacterial property, heat retention property, antiallergic property and the like. The cross-sectional shape of the fiber used here is not particularly limited, and is not limited to a circular or elliptical shape, but may be flat, triangular, or Y.
Molds, T-shapes, U-shapes, star-shapes, dog-bone-shapes, etc., so-called irregular cross-sectional shapes, hollow shapes, branched shapes, and pulp shapes may be used. ,
A circular or oval shape is most preferable.

The actual crimped fiber used in the present invention is:
Those having latent crimpability are more preferred. Latent crimping fiber is a composite fiber in which two kinds of polymers having different components are arranged in an eccentric core-sheath type or a side-by-side type.
It refers to a fiber that develops a crimp due to the difference in shrinkage between the two polymers.

There is no particular limitation on the polymer constituting the latently rollable crimped fiber, and fibers obtained by appropriately combining those having different shrinkage rates can be used. Examples thereof include polyester and modified polyester, polyester and nylon, and polypropylene. Examples include a combination of modified polypropylene and the like.

By developing latent crimps, not only can the low modulus nonwoven fabric be given bulkiness, but also the feel of the nonwoven fabric can be improved. In addition, although stretch recovery can be imparted, if the latent crimp is developed too strongly, the web entangled by the water flow becomes too entangled between the fibers, and conversely, the modulus decreases.
Therefore, it is preferable to develop crimps within a range that does not impair the performance of the nonwoven fabric.

Next, a state in which these fibers are uniformly mixed will be described. By uniformly blending the apparently crimped fibers and the ultrafine fibers that constitute the nonwoven fabric, not only can a nonwoven fabric having a low basis weight and evenness be obtained, but also a nonwoven fabric having a good texture with the low modulus properties of the manifested crimped fibers maintained. can get. Non-woven fabrics that are not uniformly mixed have unevenness and are inferior in touch to uniform ones.

As a method for obtaining a uniformly mixed nonwoven fabric, wet papermaking is a preferred method. By dispersing the fibers in water, ultrafine fibers enter between the apparently crimped fibers to obtain a uniform dispersion. Can be The ultrafine fibers used in the present invention are difficult to use in the dry method, and it is also difficult to mix uniformly.

[0029] In addition, the dry method has a poor formation, has a low basis weight, and does not provide a practical nonwoven fabric which does not cause stains of the medicine.

Next, the state of three-dimensional entanglement refers to a state in which fibers are entangled with each other. The weaker the entanglement, the lower the modulus of the nonwoven fabric obtained. However, if the entanglement is too weak, fluffs and pills are easily formed on the surface, which is not preferable.
Conversely, if the confounding is too strong, the modulus increases, which is not preferable. Specifically, it is preferable that the degree of confounding is such that fluff is not removed when the finger is rubbed several times with a finger.

In the present invention, it is preferable that the apparently crimped fibers and the ultrafine fibers are not bonded to each other. In the case where these fibers are in contact with each other at all or at least a small portion, the stretch recovery is improved, but the modulus is increased, and the fit is reduced, which is not preferable.

In the present invention, at least 10
It is preferable that the% modulus is 1.0 N / cm or less. Here, the one direction refers to any one of a running direction and a direction perpendicular to the running direction when the wet-type low-modulus nonwoven fabric of the present invention is continuously manufactured. If the 10% modulus in both directions is greater than 10%, the fit is poor, which is not preferable.

There is no particular limitation on the basis weight of the low modulus wet nonwoven fabric of the present invention, but it is possible to cope with the basis weight lower than that of the conventional nonwoven fabric, but in consideration of a practical range, it is 40 to 80 g.
/ M2 is preferred.

Next, the method for producing the wet low-modulus nonwoven fabric of the present invention will be described. The nonwoven fabric of the present invention is produced by a process for producing a web before entanglement, a process for three-dimensionally entangled fibers, and a process for removing (drying) water. Further, it is produced from a step of developing a latent crimp.

The web before the entanglement is optimally wet-processed in order to uniformly mix the ultrafine fibers and the actual crimped fibers. In the dry method, not only uniform fiber mixing but also ultrafine fibers cannot be used. Here, the web production method by the wet papermaking method will be described in detail. First, the ultrafine fibers and the apparently crimped fibers are put into water, mixed with a rotary device such as a pulper, defibrated and dispersed to prepare a fiber suspension having a concentration of about 0.1 to 3%. Next, the suspension is used to make a paper using a paper machine having at least one wire such as a long net, a short net, and a circular net to obtain a web before entanglement.

With only the actual crimped fiber, the fiber is liable to be entangled or floc at the time of defibration and dispersion, and it is difficult to obtain a uniform unentangled web. Not only penetrates between the apparently crimped fibers to enable uniform fiber mixing, but also prevents the fibers from becoming entangled or floc, and also provides a uniform web with good texture. Furthermore, even with a low basis weight, there is an effect that the ultrafine fibers serve as a barrier and can suppress the exudation of the plaster to the opposite side.

Next, the web thus obtained is
It is placed on a porous support, and a high-pressure columnar water stream is jetted to entangle the fibers to obtain an entangled web. The porous support is preferably a wire or a punching plate, and for example, a wire equivalent to 60 to 150 mesh is preferable.

The diameter of the nozzle for jetting the high-pressure water flow is 10 to 5
The range of 00 μm is preferable, and the interval between nozzles is 10 to 15
00 μm is preferred.

These nozzles need to have a range which can be processed by a water flow at least once or more in the width direction of the conveyed web. Water pressure used for confounding is 5-50
It is preferable to use in the range of kg / cm ² . More preferably, it is 10 to 30 kg / cm ² . 5kg / cm ²
If it is smaller, the confounding is insufficient and fluff and pills are generated, which is not preferable. If it is larger than 50 kg / cm ² , the confounding becomes too strong, and the modulus becomes large, which is not preferable. Also, the tactile sensation is reduced.

The processing speed is preferably in the range of 3 to 100 m / min.

The entangled web thus obtained is dried after removing excess water by a method such as suction or wet pressing. As a device for drying, a cylinder dryer, an air dryer, an air through dryer, a suction dryer and the like are preferable, and the device can be used at a temperature at which water is substantially completely removed.

When fibers having latent crimpability are used as the nonwoven fabric of the present invention, a nonwoven fabric which is bulky and more excellent in tactile sensation can be obtained by developing latent crimp.

The entangled web obtained from the fiber group containing latently crimped fibers is developed at the same time as drying or after drying at a temperature at which crimping of the latently crimpable fibers is developed. . Examples of the heat treatment method include a method of raising the atmosphere of the dried entangled web using an apparatus such as an air through dryer, an air dryer, and an infrared dryer, and a method of contacting with a cylinder dryer.

[0044]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
“Parts” and “%” in the examples mean “parts by weight” and “% by weight”, respectively. In addition, the physical property in an Example and a comparative example was measured by the following method. The samples manufactured in Examples and Comparative Examples were left for 24 hours under conditions of 20 ° C. and 65% relative humidity, and then used for measurement.

1) <Density> Measured according to the method described in JIS L 1096. The unit is g / m ² .

2) <Thickness> According to the method described in JIS L 1096, a load of 20 g / m
Measured at ² . The unit is μm.

3) <Modulus> A 50 × 300 mm sample piece was sampled in the vertical and horizontal directions.
Using a tensile tester, span (gripping interval) 200
The stress at the time of pulling 20 mm (10% elongation with respect to the span) at a pulling speed of 200 mm / min in cm was measured. Any smaller value was used as the modulus. The unit is N
/ Cm.

4) <Tactile sensation> Sensory evaluation was performed. Goods judged good were marked with ○, those judged normal were marked with △, and those judged bad were marked with x, and the numbers are shown.

5) <Surface properties> When the surface of the nonwoven fabric was rubbed with a finger,
A hair ball or fluff was marked with △, and one that did not change was marked with ○.

In addition, in certain items described in the following table, the fiber composition is part, the fiber diameter is μm, the fiber length is mm, and the number of crimps is
The unit is inch. The aspect ratio is unknown.

Examples 1 to 12 and Comparative Examples 1 to 10 Non-woven fabrics were produced according to the formulations shown in Tables 1 to 3 by the following method. In addition, the fiber which consists of a polyester was used for both the apparent crimped fiber and the ultrafine fiber. This will be described in detail below. First, the apparently crimped fiber and the ultrafine fiber were uniformly disintegrated and dispersed in water using a pulper to prepare a 1% concentration suspension. It was confirmed visually that the fibers were uniformly mixed. Then, after using the suspension to obtain a paper web having a basis weight of 70 g / m ^{2 in} terms of dry weight, the paper web is loaded on a 90-mesh twill-woven plastic wire, and the web is shown below. With three nozzle rows,
Entangling was performed at a pressure of 30 kg / cm ² and an entangling speed of 10 m / min. Further, the web was inverted, and a water stream was jetted under the same conditions to perform the confounding.

The nozzle diameter, nozzle interval, and nozzle arrangement are shown below. The first one has a nozzle diameter of 120 μm and the nozzle interval 1.2 mm arranged in two rows in a staggered manner. The second row has a nozzle diameter of 1
00 μm, nozzle interval 0.6 mm, straight one line,
The third column has a nozzle diameter of 100 mm and a nozzle interval of 0.6 mm.
Are in a straight line.

The entangled web thus obtained was squeezed out of excess water with a mangle, and then dried with an air dryer.
After drying at 20 ° C., a low-modulus wet nonwoven fabric intended for the present invention was obtained. Physical properties are described in Tables 1 to 3.

From Tables 1 to 3, it was found that a low modulus wet nonwoven fabric which could not be obtained by the conventional method can be obtained by using the apparently crimped fiber and the ultrafine fiber according to the present invention.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

[Table 3]

Example 13 A side-by-side type polyester fiber having latent crimpability was used as the actual crimped fiber.
The procedure was performed in the same manner as in Example 2 except that the heat treatment was performed at ℃. The number of crimps developed by the heat treatment was 30 pieces / inch at 150 ° C. Table 4 shows the physical properties. In the case of Example 13, crimps were newly developed, so that the bulk increased and a softer nonwoven fabric could be obtained.

Comparative Example 11 The same procedure as in Example 2 was carried out, except that a latently crimpable fiber having no apparent crimp was used. The number of latent crimps is 150 ° C
Was 30 pieces / inch. When the fiber having the dimensions of the present invention was used without using the apparently crimped fiber as in Comparative Example 11, the sheet was tight and the nonwoven fabric had a hard feel.

Comparative Example 12 A web was formed by a card method using 100 parts of a polyester latently crimped fiber having a fiber diameter of 15 μm and a fiber length of 51 mm.
The same procedure as in Example 1 was carried out, except that the layers were laminated with a crossper so as to have a basis weight of 70 g / m ² , and then subjected to hydroentanglement at a pressure of 50 kg / cm ² . The modulus was small and the texture was good, but the weight was uneven. When a 20 cm × 20 cm square web was cut into 2 cm squares and each weight was measured, 30 to 100 g /
m ² . On the other hand, when the web of Example 2 was measured by the same method and found to be 50 to 85 g / m ² ,
It was confirmed that the weight unevenness was large. It is considered that the wet type has a lower basis weight and can prevent the exudation of the plaster.

Comparative Example 13 The web before entanglement obtained in Comparative Example 12 was entangled by a needle punch method. The heat treatment was performed in the same manner as in Example 1. As in Comparative Example 12, the modulus was small and the hand was good, but the weight was uneven. 20cm × 20cm
The square web was cut into 2 cm squares, and each weight was measured. The weight was in the range of 30 to 100 g / m ² .

Comparative Example 14 Except for using 60 parts of apparently crimped fiber, 20 parts of a polyester-based low melting point fused fiber (1.5 denier, 10 mm) having a core-sheath structure and melting at 110 ° C., and 20 parts of ultrafine fiber Is
Performed in the same manner as in Example 1. Since the low melting point fiber was melted and adhered to other constituent fibers, the modulus was increased, and the nonwoven fabric aimed at by the present invention could not be obtained.

The results of Example 13 and Comparative Examples 11 to 14 are shown in Table 4.

[0064]

[Table 4]

[0065]

From the above, it can be seen that the low-modulus wet nonwoven fabric obtained by the present invention is a low-modulus wet nonwoven fabric which is not only low in modulus and excellent in fitting property but also has little bleeding from the back surface. It is effective as a base material for a transdermal suction agent (a base cloth for a poultice) or a support material for a gel for heat cooling.

Claims (5)

[Claims] 1. A fiber having a fiber diameter of 10 to 20 μm and a fiber length of 7 to 15
mm, the number of actual crimped fibers of 6 to 20 crimps / inch
~ 99% by weight, aspect ratio 1000 ~ 1500,
An ultrafine fiber having a fiber diameter smaller than that of the actual crimped fiber is 1 to 50.
% By weight, these are uniformly mixed and 3
A low-modulus wet nonwoven fabric that is dimensionally entangled, has no fusion between fibers, and has a 10% modulus in at least one direction of 1.0 N / cm or less. 2. A fiber having a fiber diameter of 10 to 20 μm and a fiber length of 7 to 15
mm, the number of actual crimped fibers of 6 to 20 crimps / inch
~ 99% by weight, aspect ratio 1000 ~ 1500,
An ultrafine fiber having a fiber diameter smaller than that of the actual crimped fiber is 1 to 50.
% By weight, at least a portion of the actual crimped fibers have latent crimpability, they are uniformly mixed and three-dimensionally entangled with each other, the fibers are not fused, and at least A low modulus wet nonwoven fabric having a 10% modulus in one direction of 1.0 N / cm or less. 3. The low-modulus wet nonwoven fabric according to claim 1, wherein the ultrafine fibers have a fiber diameter of 2 to 8 μm. 4. An entangled web obtained by uniformly blending a tangible crimped fiber and an ultrafine fiber in water to form a papermaking web, loading it on a porous support, and jetting a high-pressure columnar water flow. A method for producing a low modulus wet nonwoven fabric, characterized by further removing moisture. 5. An apparently crimped fiber containing fibers having latent crimpability and ultrafine fibers are uniformly mixed in water to form a web, which is loaded on a porous support, and jetted with a high-pressure columnar water stream. A method for producing a low-modulus wet nonwoven fabric, wherein latent crimps are developed while removing water from the obtained entangled web or after removing water.