JPH0967748A - Bulky nonwoven fabric and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a bulky nonwoven fabric, excellent in abrasion resistance and having many ridges formed on both surfaces thereof. SOLUTION: This bulky nonwoven fabric is obtained by carrying out the treatment of a fibrous web comprising 10-60wt.% heat shrinkable fibers having at least 50% maximal heat shrinkage factor and 90-40wt.% nonshrinkable fibers substantially without shrinking with high-pressure water stream at a temperature for shrinking the heat shrinkable fibers, interlacing the mutual fibers, integrating the fibers and then heat-treating the integrated fibers at a temperature near the melting point of the heat shrinkable fibers, thereby mutually heat bonding the constituent fibers, thermally shrinking the heat shrinkable fibers and forming many ridges 2 on both surface of the nonwoven fabric.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bulky non-woven fabric having a large number of ridges formed on both sides, which can be effectively used as a wiper or towel.

[0002]

2. Description of the Related Art Heretofore, various bulky nonwoven fabrics having an increased apparent thickness of the nonwoven fabric have been proposed. For example, in JP-A-2-160962, as a nonwoven fabric suitable for wipers and bandages, a bulky nonwoven fabric in which a crepe is formed on the surface by utilizing the shrinkability of elastic fibers such as highly spirally crimped fibers and elastomer fibers Is proposed. Further, in JP-A-62-141167, a heat-shrinkable sheet and a non-heat-shrinkable sheet are partially bonded and integrated, and then heat-treated to form a convex portion between the bonding portion and the bonding portion. A bulky nonwoven fabric has been proposed. Furthermore, JP-A 1-2
Japanese Patent No. 01569 proposes a bulky reinforced nonwoven fabric comprising a web containing heat-fusible fibers and a monofilament having a large heat shrinkage, and wrinkles formed on the surface by utilizing the shrinkage force of the monofilament.

Highly shrinkable fibers are disclosed in Japanese Patent Laid-Open No. 60-27.
The polyvinyl alcohol fiber using the water-swelling action described in Japanese Patent Application Laid-Open No. 09 is put to practical use, and is also disclosed in JP-A-58.
There is an example of a polyolefin-based heat-shrinkable fiber using an α-olefin having a carbon number of butene or more and a propylene copolymer having a propylene content of 50 to 85 mol%, which utilizes the heat-shrinkage property described in JP-A-214550. Furthermore, examples of the heat-shrinkable fibers having a maximum shrinkage of 50% or more include the fibers of the ethylene-propylene random copolymer and the ethylene-propylene-butene-1 terpolymer previously proposed by the present applicant (Japanese Patent Laid-Open No. Hei 10 (1999) -242242). 5-44108).

[0004]

Generally, not only household wipers but also wipers for large wiping amount have a large number of irregularities on the surface, and the wiped portions are pushed into the recesses, and the wiper surface is not covered. Ideally, it should be kept clean so that it does not leave too much residue. Therefore, it can be said that the bulky non-woven fabric is most preferable as the wiper because many ridge-like irregularities are formed on the surface and the irregularities are not easily flattened by tension or the like.

However, the bulky non-woven fabric proposed in the above-mentioned Japanese Patent Laid-Open No. 2-160962 is suitable for scratches, bandages, cushion covers, etc., because it exhibits elasticity when heated. When used as a wiper or towel, there is a problem that the crepe easily stretches. In addition, the surface of the bulky nonwoven fabric described in JP-A-62-141167 is in a state in which the nonwoven fabric is swollen between the bonding portions rather than forming the convex portions. Such a "bulge" is
When surface pressure is applied, it is easy to flatten. In addition, JP-A-1-
It cannot be denied that the non-woven fabric proposed in 201599 lacks flexibility because the monofilament having a relatively large fineness remains inside as a core material.

[0006] Therefore, in order to solve these problems, the applicant of the present invention has provided on one side or both sides of a first fiber layer containing 50% by weight or more of highly shrinkable fibers having a maximum heat shrinkage of at least 50%. In a nonwoven fabric in which a second fiber layer composed of fibers that do not substantially heat shrink at the temperature at which the shrinkable fiber shrinks is located, and both fiber layers are integrated by interfiber entanglement, A bulky nonwoven fabric in which a large number of wrinkle-shaped irregularities are formed in a fiber layer has been previously proposed.
This bulky non-woven fabric has the advantage that the unevenness is not easily broken and the wiping effect is long-lasting and is flexible.

However, this bulky non-woven fabric requires two fiber layers to be prepared, laminated and then subjected to high-pressure water flow treatment, and the manufacturing process cannot be denied. Further, when a fiber that does not exhibit thermal adhesiveness such as rayon fiber is used as the second fiber layer, the resulting non-woven fabric is inferior in abrasion resistance, and fluff tends to occur when used as a wiper. There are also problems.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a bulky nonwoven fabric excellent in basic wiping performance and improved in abrasion resistance.

[0009]

In order to solve the above-mentioned problems, the present invention provides a heat-shrinkable fiber having a maximum heat shrinkage of at least 50%, which is heat-shrinked in an amount of 10 to 60% by weight, and the heat-shrinkable fiber. Is a non-woven fabric containing 90 to 40% by weight of non-shrinkable fibers that do not substantially shrink at a temperature at which the fibers shrink, and the fibers constituting the non-woven fabric are heat-bonded by the heat-shrinkable fibers, and A large number of ridges are formed on both sides of the nonwoven fabric.

In the non-woven fabric, the heat-shrinkable fibers are
A fiber made of a polymer containing 70% by weight or more of an ethylene-propylene random copolymer having a melting peak temperature (Tm ° C) of 130 <Tm <145 is preferable.

In the non-woven fabric, the non-shrinkable fiber is preferably a hydrophilic fiber, and the hydrophilic fiber is more preferably a rayon fiber having a Y-shaped cross section.

The method for producing such a bulky nonwoven fabric comprises heat shrinkable fibers 10 to 6 having a maximum heat shrinkage of at least 50%.
A high pressure water stream treatment is applied to a fiber web composed of 0% by weight and 90 to 40% by weight of non-shrinkable fibers that do not substantially shrink at the temperature at which the heat-shrinkable fibers shrink, and the fibers are entangled to be integrated. After that, heat treatment is performed at a temperature near the melting point of the heat-shrinkable fibers to heat-bond the constituent fibers to each other and simultaneously heat-shrink the heat-shrinkable fibers to form a large number of ridges on both sides of the nonwoven fabric. Characterize. The contents of the present invention will be described below.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The nonwoven fabric of the present invention comprises heat-shrinkable fibers and non-shrinkable fibers, and only heat-shrinkable fibers are heat-shrinkable in a state where the heat-shrinkable fibers and the non-shrinkable fibers are entangled. By doing so, the non-shrinkable fiber is bent and bent, and as a result, bulkiness is imparted and a large number of ridges are formed on both sides. Therefore, in the nonwoven fabric of the present invention, the heat shrinkable fiber having a maximum heat shrinkage of at least 50% is 10 to 6%.
It is preferably contained at 0% by weight. Here, the maximum heat shrinkage ratio means the maximum heat shrinkage ratio of the heated fibers while maintaining the shape of the fibers. Maximum heat shrinkage is 5
When less than 0% of the heat-shrinkable fiber is used, or when the proportion of the heat-shrinkable fiber is less than 10% by weight, the heat shrinkage of the whole nonwoven fabric is insufficient and the nonwoven fabric cannot be provided with bulkiness. . If the proportion of heat-shrinkable fibers exceeds 60% by weight, the nonwoven fabric becomes hard, which is not preferable.

The heat-shrinkable fiber having a maximum heat shrinkage of at least 50% has a melting peak temperature (Tm ° C.) of 13
A fiber made of a polymer containing 70% by weight or more of an ethylene-propylene random copolymer in the range of 0 <Tm <145 ° C. (hereinafter, this fiber is abbreviated as EP fiber) can be mentioned. Here, the melting peak temperature means the temperature at which the DSC curve shows the highest value when the heat of fusion of the polymer is measured by a differential scanning calorimeter (DSC). If the melting peak temperature is less than 130 ° C., the polymer will exhibit rubber-like elasticity, and the fiber cardability will be poor. On the other hand, if the temperature exceeds 145 ° C., the heat shrinkability of the fiber will be as high as that of ordinary polypropylene, which is not preferable. Further, it is desirable that the ethylene-propylene random copolymer is contained in an amount of 70% by weight or more. 70
This is because the maximum heat shrinkage ratio of the fiber is less than 50% when the content is less than weight%.

A fiber made of only an ethylene-propylene random copolymer and stretched about 3 times exhibits a heat shrinkage ratio of about 93% within 1 minute at 135 ° C. just below the melting point. Therefore, another polymer may be mixed in order to control the heat shrinkability. As the polymer to be mixed, ethylene-butene-1
-Propylene terpolymers are preferred. You may mix polyolefin polymers, such as polypropylene.

In the present invention, the constituent fibers are required to be thermally bonded to each other in order to improve the abrasion resistance of the non-woven fabric. The EP fibers exhibit heat shrinkability at a specific temperature and at the same time soften or melt. Since it also exhibits thermal adhesiveness, it is most preferably used in the present invention.

The non-shrinkable fiber mixed with the heat-shrinkable fiber is
The material is not particularly limited as long as it does not substantially shrink at the temperature at which the heat-shrinkable fiber shrinks. For example, recycled fibers such as rayon, semi-synthetic fibers such as acetate, cotton,
Natural fibers such as wool, polypropylene, polyethylene,
Any one or more of synthetic fibers such as polyester, nylon, vinyl chloride and vinylon can be selected and used. Also, the fiber shape and the like are not limited, and split-type composite fibers, fibers having an irregular cross section, and the like can be arbitrarily used.

The proportion of non-shrinkable fibers in the non-woven fabric is 9
It is preferably from 0 to 60% by weight. If it is less than 60% by weight, the proportion of the heat-shrinkable fibers becomes too large and the nonwoven fabric becomes inflexible, and if it exceeds 90% by weight, the proportion of the heat-shrinkable fibers becomes small and sufficient bulkiness is obtained. I can't.

When the non-woven fabric of the present invention is used as a wiper, if the non-shrinkable fiber is composed of hydrophilic fiber, it is suitable for wiping off moisture or impregnating the non-woven fabric with a detergent. . The hydrophilic fibers that can be used in the present invention include regenerated fibers such as rayon, natural fibers such as cotton and pulp, and hydrophobic synthetic fibers that have been subjected to a hydrophilization treatment. Of these, rayon is preferable because it is highly water-absorbent and staple fibers of a certain length are easily available. Moreover, rayon fibers having a Y-shaped fiber cross section are particularly preferable because they exhibit excellent water absorption.

Next, the structure of the bulky nonwoven fabric of the present invention will be described together with the manufacturing method. First, in order to obtain the nonwoven fabric of the present invention, it is necessary to subject the fiber web formed by mixing the above-mentioned heat-shrinkable fiber and non-shrinkable fiber to high-pressure water jet treatment to entangle the fibers. Here, the fibrous web is that it is easy to mix two or more kinds of fibers, and that the entanglement of the fibers due to the high-pressure water stream treatment easily proceeds,
It is preferably composed of staple fibers. The web may be any of parallel web, cross web, semi-random web, random web, and the like, but when a web in which fibers are arranged in one direction like a parallel web is used, the heat shrinkage of the fibers is reduced. Since it advances in the direction, it is possible to obtain a non-woven fabric which has uniform ridges on the non-woven fabric surface and which has an orderly appearance.

In this case, the fiber length of the staple fiber is 38 to 76 mm in consideration of the card passing property and the texture of the web.
It is preferred that Further, the basis weight of the fibrous web needs to be determined in consideration of the increase in surface shrinkage during the subsequent heat treatment. However, when the fiber web is used as a wiper, the basis weight after heat shrinkage is 30 in consideration of ease of use. ~ 85
It is advisable to determine the basis weight so that it will be g / m ² .

The high-pressure water stream treatment can be carried out by a conventionally well-known method, and the conditions may be set according to the basis weight of the nonwoven fabric to be finally obtained. For example,
When processing a fiber web having a basis weight of 30 to 70 g / m ² ,
Orifice with a hole diameter of 0.05 to 0.5 mm is 0.5 to 1.5
Water pressure 30 to 60 kg / cm ² from nozzles provided at mm intervals
The columnar water streams of 1 to 4 from the front and back sides of the fiber web, respectively.
It is good to spray each time.

If the fiber web has a large basis weight,
The fibers may be entangled with each other by needle punching instead of the high-pressure water stream treatment.

Next, heat treatment is performed to soften and melt the heat-shrinkable fibers to thermally bond the constituent fibers to each other, and at the same time heat-shrink the heat-shrinkable fibers to form ridges on both sides of the nonwoven fabric.
Therefore, it is desirable that the heat treatment be performed at a temperature near the melting point of the heat-shrinkable fiber. For example, when the above EP fiber is used as the heat shrinkable fiber, the heating temperature (T ° C.) is 110 <
It is necessary to set it in the range of T ≦ Tm + 30 (Tm: melting peak temperature), and preferably 135 <T <145. When the temperature is 110 ° C or lower, the EP fiber does not exhibit thermal adhesiveness, and when the temperature exceeds Tm + 30 ° C, the shrinkage of the fiber proceeds excessively and the nonwoven fabric becomes hard.

The method of heat treatment is not particularly limited, but for example, a hot air penetrating dryer may be used.

The bulky nonwoven fabric of the present invention thus obtained has a large number of ridges formed on both sides thereof. A change in the thickness of the nonwoven fabric after heat treatment can be mentioned as a measure of the size of this ridge. That is, when the area shrinkage ratio of the nonwoven fabric after heating is constant, the smaller the change in thickness after heat treatment, the more fine ridges are formed. In the bulky non-woven fabric of the present invention, the non-woven fabric after heat treatment under the condition that the area shrinkage of the non-woven fabric is about 40 to 85%, that is, the area after heat treatment is 60 to 15% before heat treatment. The thickness is preferably 2 to 6.5 times the thickness of the non-woven fabric before heat treatment. If it is less than 2 times, the ridges formed become too fine, and when used as a wiper, dust cannot be adsorbed by the ridges, and if it exceeds 6.5 times, the ridges become large and the number decreases, so wiping It cannot substantially contribute to the improvement of the sex. Particularly, in the present invention, the area shrinkage ratio after the heat treatment is 50 to
It is desirable that the change in thickness after heat treatment is 65%, which is 2.5 to 3.5 times.

[0027]

EXAMPLES The present invention will be described below with reference to examples.

[Production of heat-shrinkable fiber] The melting point is 136 ° C.,
An ethylene-propylene random copolymer having a melt flow rate value (230 ° C.) of 15 g / 10 min was spun at a spinning temperature of 260.
It was melt spun at ℃. Then, this was stretched 3.6 times in hot water at 90 ° C., and while the fiber treatment agent was applied, mechanical crimping of 16 pieces / inch was performed in a stuffing box,
After being dried in a hot-air penetrating dryer at 0 ° C. for 15 minutes, the staple fiber was cut to obtain 2 denier and 51 mm staple fiber.
The maximum heat shrinkage of this fiber is 92% at 150 ° C. The maximum heat shrinkage is calculated by bundling 50 fibers, marking them with black cotton threads at predetermined intervals, exposing them to a temperature of 150 ° C for about 30 seconds, and then measuring the marked intervals. Was obtained by doing. Although the temperature is higher than the melting peak temperature here, the treatment time is short, so that the fiber can be shrunk while maintaining the fiber shape.

(Preparation of Sample 1) The above heat-shrinkable fiber 3
0% by weight, Y-shaped fiber cross section, fineness 1.7 denier, fiber length 44 mm rayon fiber (trade name: SA rayon CDA
70% by weight of Type Daiwa Bourayon Co., Ltd. was mixed to prepare a parallel web having a basis weight of 30 g / m ² . An orifice with a hole diameter of 0.13 mm is 1 mm in this web.
A columnar water stream with a water pressure of 40 kg / cm ² was jetted twice each from the front and back sides from nozzles provided at intervals, and the fibers were entangled and integrated with each other, and then the hot air penetration dryer was used to
Dried at 0 ° C. Then, this non-woven fabric is subjected to heat treatment at 140 ° C. for 30 seconds using a hot-air penetrating dryer to soften the heat-shrinkable fibers and heat-bond the fibers at the same time.
The heat-shrinkable fiber was shrunk to obtain a bulky nonwoven fabric (1) having a large number of ridges (2) formed on both sides of the nonwoven fabric as shown in FIG.

(Preparation of Sample 2) Instead of the heat-shrinkable fiber used in Sample 1, the core component / sheath component was polypropylene /
Using a core-sheath type composite fiber (trade name NBF (H): manufactured by Daiwa Spinning Co., Ltd.) having high-density polyethylene thermal adhesiveness,
30% by weight of this was mixed with 70% by weight of rayon fiber to prepare a parallel web having a basis weight of 70 g / m ² ,
A nonwoven fabric was prepared in the same manner as in Sample 1.

(Preparation of Sample 3) Instead of the rayon fiber having a Y-shaped cross section used in Sample 1, ordinary rayon fiber having a fineness of 1.5 denier and a fiber length of 40 mm was used.
A non-woven fabric was prepared in the same manner as in.

(Preparation of Sample 4) A parallel web having a basis weight of 10 g / m ² consisting only of heat-shrinkable fibers and a parallel web having a basis weight of 20 g / m ² consisting of rayon fibers having a Y-shaped fiber cross section used in Sample 1. Was laminated, and the laminate was subjected to a high-pressure water stream treatment and a drying treatment in the same manner as in Sample 1. Then, using a hot air penetration dryer,
By heat-treating for 0 seconds to shrink the heat-shrinkable fiber layer, a bulky nonwoven fabric having a large number of ridge-shaped irregularities formed on the rayon fiber layer was obtained.

Table 1 shows the performance of the non-woven fabrics of Samples 1 to 4.

[0034]

[Table 1]

In Table 1, each performance was measured according to the following method.

(1) Thickness: Thickness measuring machine (Product name: THICKN
Using an ESS GAUGE model CR-60A (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.), measurement was performed with a load of 3 g per cm ^{2 being} applied to the sample. (2) Area shrinkage: 20 cm on the surface of the non-woven fabric before heat treatment
Place a square frame of × 20 cm, and mark the position corresponding to the midpoint (4) of each side of the square (3) as shown in FIG. Then, after the heat treatment, the midpoints (4) facing each other were connected by a line, and as a result of the heat shrinkage, the square became a rectangle (5) having the lines as the sides of the vertical (6) and the sides of the horizontal (7). The area of the rectangle (5) was calculated as if it were one. From this result, the area shrinkage rate was calculated by the following equation.

[0037]

[Equation 1]

Example 1 Samples 1 and 2 were compared in dust adsorption amount and retention amount. First, 1 g of test dust was evenly sprinkled on a 25 × 25 cm slate plate, and the sample was fixed on a 6.5 × 11 cm sponge.
The sample was reciprocated, the amount of dust adsorbed on the sample was measured, and this was taken as the adsorption amount. Then, the sample having adsorbed dust was dropped from a height of 50 cm five times, and the amount of dust retained in the sample was measured, and this was taken as the dust retention amount. Then, the same test was performed on the dust obtained by mixing 1 type of test dust and 7 types of dust at a ratio of 1/1. Table 2 shows the results.

[0039]

[Table 2]

[Example 2] The water absorptions of Sample 1 and Sample 3 were compared. The water absorption is evaluated by the surface water absorption method (Larrose method) of the water absorption test method (JIS L 1907) of textile products.
It measured according to. However, the measurement was performed with the donut plate removed. Further, each sample was allowed to stand overnight in an atmosphere having a temperature of 20 ° C. and a humidity of 65% and then measured. The changes over time in the water absorption amount and water absorption speed are shown in FIGS. 3 and 4.

[Example 3] The wear resistance of Sample 1 and Sample 4 was compared. The abrasion test is performed according to the JIS L 1096 universal type method, and the pressing load is 2 pounds (about 0.9
1 kgf) and the sample was polished paper (JIS R 62
53 AA-400) was rubbed 50 times to observe the surface condition of the non-woven fabric to compare the abrasion resistance of both. Sample 1
Although fluff and fluff were observed on the surface, there was no tearing or perforation, and the back surface was still usable enough. On the other hand, the sample 4 had a hole and was no longer usable.

[0042]

As described above, the nonwoven fabric of the present invention has a large number of ridges formed on the surface thereof and is suitable for wiping off dust. Further, unlike the conventional bulky nonwoven fabric of the present invention, since it is obtained by mixing heat-shrinkable fibers and non-shrinkable fibers, in addition to being easy to manufacture, the nonwoven fabric surface Since ridges are formed on both back surfaces, both sides can be wiped off economically when used as a wiper.

In the present invention, the heat-shrinkable fibers also act as heat-adhesive fibers, and the constituent fibers of the non-woven fabric are heat-bonded. Therefore, the non-woven fabric of the present invention is excellent in abrasion resistance and can be used as a wiper. When used, the life is improved.

Furthermore, when rayon fiber having a Y-shaped fiber cross section is used as the non-shrinkable fiber, the initial water absorption rate is increased, so that water can be quickly wiped off and the water absorption amount is also increased, so that the detergent is impregnated. It is also suitable for use.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a bulky nonwoven fabric of the present invention.

FIG. 2 is a schematic diagram showing an area shrinkage evaluation method.

FIG. 3 is a graph showing a change with time in water absorption when the type of rayon fiber is changed.

FIG. 4 is a graph showing changes with time in water absorption rate when the type of rayon fiber is changed.

[Explanation of symbols]

 1 Bulky non-woven fabric 2 Ridge

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location D04H 1/54 D04H 1/54 C

Claims (5)

[Claims] 1. A heat-shrinkable fiber having a maximum heat shrinkage of at least 50%, which is heat-shrinked by 10 to 60% by weight, and a non-shrinkable fiber which does not substantially shrink at a temperature at which the heat-shrinkable fiber shrinks. 90% to 40% by weight of a non-woven fabric in which the fibers are entangled with each other, the fibers constituting the non-woven fabric are heat-bonded by the heat-shrinkable fibers, and a large number of ridges are formed on both sides of the non-woven fabric. A characteristic bulky nonwoven fabric. 2. The heat shrinkable fiber has a melting peak temperature (Tm).
The bulky nonwoven fabric according to claim 1, which is a fiber made of a polymer containing 70% by weight or more of an ethylene-propylene random copolymer having a temperature of (C) of 130 <Tm <145. 3. The bulky nonwoven fabric according to claim 1 or 2, wherein the non-shrinkable fiber is a hydrophilic fiber. 4. The bulky nonwoven fabric according to claim 3, wherein the hydrophilic fiber is a rayon fiber having a Y-shaped fiber cross section. 5. 10 to 60% by weight of heat-shrinkable fibers having a maximum heat shrinkage of at least 50%, and non-shrinkable fibers 90 that do not substantially shrink at the temperature at which the heat-shrinkable fibers shrink.
A high pressure water stream treatment is applied to a fibrous web of 40 wt% to 40% by weight, and the fibers are entangled to be integrated with each other, and then heat treated at a temperature near the melting point of the heat shrinkable fibers to thermally bond the constituent fibers together. At the same time, the heat-shrinkable fiber is heat-shrinked to form a large number of ridges on both sides of the nonwoven fabric, which is a method for producing a bulky nonwoven fabric.