JPH06128853A - Nonwoven fabric for sanitary material - Google Patents

Abstract

PURPOSE:To obtain a bulky nonwoven fabric for sanitary materials excellent in dry touch properties and feel without repetitive deteriorating wet back and water absorption rate. CONSTITUTION:This nonwoven fabric for sanitary materials is obtained by laminating and integrating a highly shrinkable fiber sheet on a low-shrinkable or a nonshrinkable nonwoven fabric and subjecting the resultant laminate to shrinking treatment under conditions so as to enable the sufficient shrinkage of the fiber sheet. The nonwoven fabric has 2-20 wrinkles 0.2-3mm deep per cm on at least one side, >=15cm<3> apparent specific volume, <=0.2% initial wet back and <=2.3sec initial absorption rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonwoven fabric suitable for surface materials such as diapers and napkins and second sheets.

[0002]

2. Description of the Related Art As a water-permeable material for sanitary materials such as diapers and sanitary napkins, heat-fusion type composite fibers or non-woven fabrics obtained by combining the fibers with other materials have been known. In this, perforated films such as polyethylene are often used. However, since all of these conventional non-woven materials have a smooth surface, they have a reversion phenomenon due to urine or body fluid and have a feeling of wetting. Further, the film has a dry feeling on the surface, but has a cool touch and a hard feeling during use. Also, in order to express the bulkiness without lowering the basis weight, the cross-sectional shape of the fiber and the single yarn fineness have been changed, and improvements such as putting a second sheet under the surface material have been made, but the nonwoven fabric becomes thick There are problems such as the product becoming stiff and uncomfortable to use, or water is retained, and in the present situation, none of them are sufficiently satisfactory.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-woven fabric for sanitary materials, which has a dry touch and is excellent in touch, without reducing repeated wet back and water absorption rate.

[0004]

That is, according to the present invention, a wrinkle having a depth of 0.2 to 3 mm is formed on at least one side at a rate of 2 per cm.
It is a non-woven fabric for sanitary materials, characterized by having ~ 20, an apparent specific volume of 15 cm ↑ 3 / g or more, an initial wet back of 0.2% or less, and an initial absorption rate of 2.3 seconds or less.

The greatest feature of the present invention is that wrinkles are formed on the surface of the non-woven fabric and the apparent specific volume is 15 cm ↑ 3 / g or more, particularly 25 cm ↑ 3 / g or more. Here, the wrinkles are formed on at least one side of the non-woven fabric, and when the surface material of the sanitary material is used, it is necessary to use the wrinkles so that the wrinkled surface contacts the skin. The wrinkles may be formed along any one direction on the surface of the non-woven fabric or may not have directionality. The wrinkle form is not particularly limited as long as it does not impair the effects of the present invention, and may be an irregular form or a regular form.

The wrinkle depth can be freely changed depending on the manufacturing conditions, but is 0.2 to 3 mm, preferably 0.3 to
It needs to be 2 mm. If the depth is less than 0.2 mm, wet back becomes poor, and the contact area between the skin and the nonwoven fabric during use tends to be large, resulting in a lack of dry touch feeling. On the other hand, if the thickness exceeds 3 mm, the shape retention of wrinkles deteriorates, it becomes technically difficult to increase the number of wrinkles per unit length, and the skin feels a little rough, and the appearance becomes unfavorable. The number of wrinkles is 1
It is necessary to have 2 to 20, preferably 3 to 10 per cm. If the number is less than 2 per cm, the surface unevenness is not sufficiently formed, resulting in poor wet back and poor dry touch feeling. If the number of wrinkles exceeds 20, it is technically difficult to set the depth of wrinkles in the above range, and the wrinkles become too fine and the situation is similar to a flat surface, and the effect of unevenness is sufficient. It will not appear.

When the specific volume is less than 15 cm ↑ 3 / g, good water absorption rate and wet back cannot be realized.
Such a specific volume can be achieved with a wrinkle-free non-woven fabric, but in the case of such a non-woven fabric, since moisture is retained in the tissue, it is not possible to obtain a dry touch feeling. I can't get it.

The fibers constituting the nonwoven fabric of the present invention are long fibers,
Short fibers or a mixture thereof may be used, and the fiber material is not particularly limited, and natural fibers such as cotton, regenerated fibers such as rayon,
It is possible to freely select synthetic fibers such as polyolefin, polyester, and polyamide, which may be used alone or in combination. The method for producing the raw material nonwoven fabric before forming wrinkles is not particularly limited, and short fibers may be used to make the nonwoven fabric by a dry method or a wet method, or a nonwoven fabric may be made by a melt blown method, a spun bond method, or the like.

There are various possible means for forming wrinkles on the surface of the non-woven fabric, but if a typical method is shown, a low-shrinkage or non-shrinkable fiber sheet having high shrinkability is used. When a nonwoven fabric (hereinafter, simply referred to as a low shrinkable nonwoven fabric) is laminated and integrated and subjected to a shrinking treatment under the condition that the fiber sheet can be sufficiently shrunk, wrinkles corresponding to the difference in shrinkage rate are formed on the surface of the low shrinkable nonwoven fabric. Can be formed. Then, if necessary, the wrinkled nonwoven fabric can be peeled off from the laminate to obtain the nonwoven fabric of the present invention (this method may be simply referred to as a lamination heat treatment method hereinafter). In particular, it is desirable to use a peeled product when lowering the basis weight and placing importance on flexibility.

In forming wrinkles, it is possible to apply wrinkles to the nonwoven fabric by a mold having a desired wrinkle shape without using such a lamination heat treatment method. In such a method, heating and compression are performed. As a result,
In many cases, the non-woven fabric is hard to the touch and feels uncomfortable during use, and the laminated heat treatment method is excellent in terms of cost.

The fiber constituting the highly shrinkable fiber sheet is not particularly limited as long as it is a highly shrinkable fiber, but it is preferable to use a fiber having a dry heat shrinkage ratio at 120 ° C. of 15% or more. As such a fiber, for example, a modified polyester fiber obtained by copolymerizing a third component such as isophthalic acid or 5-metalsulfoisophthalic acid with several mol% to several tens mol%, an acrylic fiber, a polyamide fiber or the like is used. However, copolyester fibers are preferably used. These fibers may be single fibers or side-by-side type or core-sheath type composite fibers.

Further, since the form of wrinkles varies depending on the areal weight ratio and the conditions of integration in the lamination, it is not possible to control the formation of wrinkles only by the difference in shrinkage ratio between the highly shrinkable fiber sheet and the low shrinkable nonwoven fabric. However, it is preferable that the difference in surface shrinkage between the two is 10% or more. In the lamination heat treatment method, the formation of wrinkles is basically based on the difference in shrinkage ratio between the nonwoven fabrics. Depending on the degree, the degree of wrinkle formation can be freely changed. When the lamination heat treatment method is adopted in the present invention, the ratio (B / A) of the basis weight A of the fiber sheet and the basis weight B of the low shrinkable non-woven fabric on which wrinkles are formed is 5 to 0.1,
In particular, by setting it to 4 to 0.3, wrinkles having excellent performance can be formed. A needle punching method or a high-pressure fluid treatment can be adopted in the lamination integration, but in order to form the wrinkles defined in the present invention, needle punching is performed at a punch density of 30 to 200 punches / cm ↑ 2. preferable. At that time, the needle punching may be performed from either side of the laminate, but from the viewpoint of the wrinkle forming property, it is desirable to perform needle punching from the side of the nonwoven fabric on which the wrinkling is formed.

Further, in order to form wrinkles uniformly, it is preferable to partially adhere or bond the nonwoven fabric before forming the wrinkles. A known mechanical method or chemical method can be adopted to cause partial adhesion or bonding, for example, strong entanglement is partially performed by high-pressure fluid treatment, or a fiber constituting a non-woven fabric is formed. The heat-adhesive fibers may be mixed and point-bonded by embossing or the like before the lamination. Further, when it is desired to form wrinkles along one direction, it is preferable to prepare a card web to form a dry non-woven fabric in which fibers are arranged in one direction and use the above-mentioned lamination heat treatment method.

In the present invention, the presence of specific wrinkles on at least one side of the nonwoven fabric exerts a performance that cannot be achieved by conventional sanitary materials. For example, with regard to wet back, the wet back of the first time is 0.2% or less by the measuring method described later, and the performance is hardly reduced even in the third time, and the wet back of 0.25% or less is achieved, Regarding the water absorption rate, the first time was 2.3 seconds or less, and the third time was 2.5 seconds or less, showing almost no deterioration in performance. Such wet back, the water absorption performance and the synergistic effect of the presence of wrinkles on the surface of the non-woven fabric eliminate the wet feeling that causes the most discomfort during use,
It is possible to always realize dry touch. In order to achieve a dry touch and a particularly good wet back, wrinkles are formed on the surface that comes into contact with the skin, and at the same time, even on the surface that comes into contact with the water absorbent so that the water once retained in the absorbent does not easily return. It is preferable that wrinkles are formed, that is, wrinkles are formed on both sides.

Since the nonwoven fabric of the present invention has a low basis weight and a high bulk, it is difficult to retain water, has a very good wet back and an excellent water absorption rate, and is flexible and has a dry touch feeling. Therefore, it is suitable for diaper liners, paper diapers and sanitary products. It is suitable as a surface material and a second sheet.

[0016]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited thereto.
The method of measuring the characteristic values and the evaluation of the cloth are as follows.

<Water absorption rate, wet back> Artificial urine 5 ml
Prepare a separatory funnel with a capacity of 50 ml, and set so that the bottom end of the funnel is located at a height of about 6 mm from the sample non-woven fabric (50 mm x 50 mm), and then put artificial urine on the sample non-woven fabric. It was quickly dropped into a 180 g weighted plastic cylinder (inner diameter 20 mm) until artificial urine passed through the nonwoven fabric and was completely absorbed by the lower absorbent body for disposable diapers (Kao Marys) (50 mm x 50 mm). The time was measured with a stopwatch, and the number of seconds was taken as the water absorption rate.

Next, the separatory funnel and the plastic cylinder were removed, and on the non-woven fabric (with the absorbent body) for which the water absorption time was measured, a polystyrene disc having a diameter of 54 mm laminated with styrene foam was placed on the styrene side downward. Then, put a weight of 572 g on it and leave it for 3 minutes. Next, the weight and the plastic plate are removed, 5 pieces of weighed Toyo Roshi [5A] are placed on the portion, and the weight and the plastic plate are placed on it and left for 2 minutes. The weight of the filter paper after 2 minutes was measured, and the weight addition to the initial weight was expressed as a ratio to the first artificial urine input, and the value was defined as the wet back (%). The initial values of both the water absorption rate and the wet back are taken as the initial water absorption rate and the initial wet back, and the respective characteristics are air-dried for 30 minutes after the completion of the first measurement, and again measured in the same manner. This was repeated 3 times and used as the second and third water absorption rates and wet back.

<Dry touch property> On the absorbent body from which the surface material of a commercially available paper diaper is removed, a sample non-woven fabric (100
X 100 mm), and 25 ml of artificial urine is flown from the height of about 10 mm above the non-woven fabric from the measuring cylinder to absorb all the artificial urine into the absorbent body, and then lightly touch the surface material with a finger to remove the artificial urine. The state of adhesion was confirmed. 1 like wetback
Evaluation is repeated twice. Drying was air-dried for 30 minutes. The evaluation was carried out on both averages of 1 to 2 times. The evaluation criteria are as follows. ⊚: No artificial urine adhered and no change on fingertips. ○: No artificial urine is attached, but the fingertip feels slightly damp. Δ: Adhesion of artificial urine is seen and the fingertips get slightly wet. X: Adhesion of artificial urine is remarkable and the entire fingertip is wet.

<Apparent thickness and apparent specific volume of the non-woven fabric> The thickness is measured by using a thickness gauge CR10B manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd. and placing a disc-shaped weight having a diameter of about 2 cm on the sample non-woven fabric. The thickness (mm) of the non-woven fabric was measured at 5 points under a load of 20 g / cm 2 and the average value was obtained. The apparent specific volume (cm ↑ 3 / g) was calculated from the basis weight (g / m ↑ 2) of the nonwoven fabric and the value of the thickness.

Example 1 A core-sheath composite fiber containing polyethylene terephthalate copolymerized with isophthalic acid at 45 mol% as a sheath component and polyethylene terephthalate as a core component (core-sheath weight ratio 1: 1,
Using a single fiber fineness of 3 denier and a cut length of 51 mm, a card web having a basis weight of 50 g / m ↑ 2 was prepared in accordance with a conventional method and used as a highly shrinkable fiber sheet. On the other hand, a core-sheath type composite fiber having polyethylene as a sheath component and polyethylene terephthalate as a core component (single fiber fineness 2 denier, cut length 5
1 mm) through a card to form a card web, and the web is placed on an embossing roll having a surface temperature of 125 ° C. and a linear pressure of 30 kg /
cm, speed is 1.3 m / min, and the press-bonding area is 25%
The processed card web (unit weight: 30 g / m ↑ 2) was prepared and used as a low-shrink non-woven fabric.

Next, a low-shrinkable non-woven fabric is laminated on the fiber sheet, and 6 per 1 cm 2 from the low-shrinkable non-woven fabric side.
A 4-punch needle punch was performed, and this was introduced into a hot air circulation dryer at 140 ° C. and heat-treated for 10 seconds to form wrinkles. Next, when the wrinkled nonwoven fabric was carefully peeled off from the laminate obtained here, wrinkles of the same shape were present on both sides of the nonwoven fabric. Then, when the depth and the number of wrinkles were examined, there were 7 wrinkles / cm with an average of 1 mm.
The apparent thickness of this nonwoven fabric was 0.98 mm, and the apparent specific volume was 27.2 cm ↑ 3 / g. The results of evaluation of this non-woven fabric as a sanitary material are shown in Table 1.

[0023]

[Table 1]

Examples 2 to 4, Comparative Example 1 A wrinkled nonwoven fabric was prepared in substantially the same manner as in Example 1 except that the basis weight ratio between the fiber sheet and the low-shrinkable nonwoven fabric was changed. The results are shown in Table 1. In Comparative Example 1, the wrinkles that appeared were too small and the number was small, so that a satisfactory surface material for the diaper could not be obtained.

Comparative Example 2 The embossed non-woven fabric used in Example 1 (Basis weight 3
An evaluation as a surface material of the diaper was performed only with 0 g / m ↑ 2), but as with the case of Comparative Example 1, satisfactory results were not obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location A61F 13/15 D04H 1/46 Z 7199-3B

Claims (1)

[Claims] 1. At least one wrinkle having a depth of 0.2 to 3 mm and 2 to 20 wrinkles per cm, and an apparent specific volume of 15 cm ↑
A nonwoven fabric for sanitary materials, which has a wet back ratio of 3 / g or more, an initial wet back of 0.2% or less, and an initial absorption rate of 2.3 seconds or less.