JPH0261149A - Surface sheet for healthy material - Google Patents

Abstract

PURPOSE:To provide the subject surface sheet having an improved touch, excellent absorbing speed and absorbing ability and good wearing feeling and abrasion resistance by needling a curd web comprising durable hydrophilic thermally weldable combinated fibers in a specific density to form penetrated holes and subsequently heat-treating the web. CONSTITUTION:A curd web comprising durable hydrophilic thermally weldable combinated fibers (e.g., fibers comprising a combination of polyethylene fibers and polypropylene fibers) having a weight of 15-30g/m<2> is needled in a density of 5-150 times/cm<2> to form penetrated holes composed of fibers which are arranged in the vertical direction based on the surface of the web, followed by heat-treating the web to provide the objective surface sheet preferably having a web thickness of 0.3-0.6mm (when a load of 20g/cm<2> is applied). The surface sheet causes no wet back and give no unpleasant feeling, thereby suitable for sanitary napkins, paper diapers, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a surface sheet for sanitary materials such as sanitary napkins and disposable diapers for the purpose of trapping blood, urine, etc.

(Prior art) Conventionally, in sanitary products such as sanitary napkins and disposable diapers that are intended to trap blood, urine, etc., in order to improve the feeling of wearing them, in addition to improving the absorption speed of the top sheet, internal absorption Attempts have been made to minimize the tendency for liquid absorbed into the body to return to the surface sheet (wet bank property).

Also, by using a superabsorbent polymer as an absorbent material, bleeding can be prevented.

In sanitary materials such as sanitary napkins and disposable diapers currently on the market, the absorbent materials that absorb menstrual blood and urine are absorbent materials that use superabsorbent polymers, as seen in the patents and products of Polytechnic. There are products on the market that are close to perfect, including . At present, there are no sheets that have excellent wet banking properties.

Most conventional surface materials are made of non-woven fabrics whose constituent fibers are arranged only in the horizontal direction, so they do not absorb blood, urine, etc. at a satisfactory rate, especially in the case of viscous liquids. This had the disadvantage that the absorption rate was further reduced.

Hydrophilic fibers, for the purpose of improving absorbency as fibers,
For example, attempts have been made to use rayon, cotton, etc. and hydrophobic fibers to obtain a top sheet made of a cotton blend, and methods to obtain a top sheet with a multilayer structure of a hydrophobic fiber layer and a hydrophilic fiber layer. However, when hydrophilic fibers are mixed in, the absorption performance is improved compared to hydrophobic fibers alone, but the wet feeling remains for a long time, making it difficult to create the necessary dry and comfortable texture on the surface. .

Utility Model Publication No. 62-20194 proposes a laminated sheet having through-holes in the multilayer structure sheet. Although this sheet has improved liquid absorption, it does not use water-absorbing paper in part of the layer. As a result, the liquid absorbed in this area does not fully transfer to the lower absorbent body, leaving a persistently wet feeling and having poor wet back properties, resulting in discomfort during long-term use.

In addition, recently, products using films with fine holes as surface materials have been seen, but these have the disadvantage that they feel plastic-like and uncomfortable when worn.

(Problems to be Solved by the Invention) Therefore, an object of the present invention is to improve the feel to the skin and improve spot absorbency when used as a surface material in the field of sanitary materials such as sanitary napkins and disposable diapers. Moreover, it is an object of the present invention to provide a top sheet that has excellent absorption speed and absorption capacity, does not cause wet back, is comfortable to wear, does not fluff during use, and has excellent abrasion resistance.

(Means and effects for solving the problem) For this reason, the present invention provides a carded web with a needle penetration density of 5 to 30 g/m made of heat-fusible conjugate fibers having durable hydrophilic properties and a basis weight of 15 to 30 g/m.
150 wood/cnl, has through-holes made of fibers arranged perpendicular to the web surface, and has the above-mentioned shape fixed by heat treatment. It is a means to accomplish a task.

Hereinafter, the present invention will be explained in detail along with its operation.

It is important to use heat-fusible conjugate fibers having durable hydrophilic properties as the fibers for this top sheet.

When hydrophobic fibers are used as fibers, they have poor liquid absorption.
On the other hand, if hydrophilic fibers such as rayon or cotton are used, the absorbency of liquid will improve, but the wet feeling will remain forever.
The disadvantage is that the wet banking property is also increased. There are surface sheets that use hydrophobic fibers whose surfaces have been temporarily made hydrophilic with an oil agent, but although these sheets initially have liquid absorption properties, over time the oil agent falls off and the sheet becomes 1B water-based. The drawback is that absorbency gradually decreases.

From this point of view, it is necessary to use fibers that have durable hydrophilic properties. The term "durable hydrophilicity" as used herein refers to a property in which the hydrophilicity is not temporary, but remains hydrophilic even after 4 to 5 washings with water.

As a method to obtain this durable hydrophilicity, an oil agent whose main component is polyhydric alcohol ester is used as an oil agent with a solid content of 0.2
It is desirable to add ~1% (based on the weight of the fiber) -1 The fibers obtained by this method were excellent in durable hydrophilicity.

If the adhesion amount is less than 0.2, the desired hydrophilicity will not be obtained, and if it is more than 1%, the wood affinity will improve, but it is not suitable because it will cause problems with passability in the subsequent processing. Met.

The reason for using heat-fusible fibers in the present invention is to stabilize the form and maintain the strength of the sheet. As the heat-fusible composite fiber, either a parallel type or a core-sheath type can be used. As the composite component, any commonly used components such as polyolefin, polyamide, polyester, etc. can be used. It is desirable that the difference in melting point between the two composite components be at least 20° C. or more, and combinations of polyethylene and polypropylene, polyethylene and polyester, low melting point polyester and polyester, etc. are preferred. The thickness of the fiber is preferably about 1 to 4 d due to its softness.

As a method for producing durable hydrophilic raw cotton, first, heat-fusible conjugate fibers are spun, drawn, and treated with an oil agent (spinning oil agent + hydrophilic oil agent), and then crimped fibers can be obtained by heat treatment for one cut.

It is also possible to treat cut raw cotton with a hydrophilic oil agent in a batch manner.

As for the manufacturing method of the sheet, first, heat-fusible conjugate fibers having durable hydrophilic properties are processed using a card to give a basis weight of 15 to 30 g.
/ get the web of tri.

The reason for limiting the basis weight to 15 to 30 g/m is as follows.

When the basis weight was less than 15 g/lri, the covering property (concealing property) as a topsheet was poor, the effect as a cushion layer was low, and the feel was also poor.

Furthermore, when used in diapers and the like, the strength was weak and the material could not withstand long-term use.

On the other hand, if it exceeds 30 g/%, there is a drawback that the absorption and diffusion of liquids becomes poor, especially the absorption of viscous liquids, and it is not suitable as a topsheet. The web may have a single layer, or two layers may be combined to form a single layer sheet.

Next, this web is punched with a known needle punching machine to form through holes in the sheet.

Since the fibers of the web released from the card are all aligned in the horizontal direction, the sheet in this state has poor liquid absorption properties, especially for viscous liquids. This sheet is punctured with a needle to create a penetrating material made of fibers arranged in the vertical direction.
Only by providing m-holes can the desired sheet be obtained.

The density of needle sticks is at least 5 needles/cnl~15
0/c++I is appropriate. If it is less than 5 wood/Cml, the liquid absorption rate will be poor, and if it is more than 150 wood/ct, there will be problems in terms of production. Further, no difference was observed in the effect even when the amount was exceeded.

After forming through-holes made of fibers arranged vertically in the web by punching with a needle punching machine as described above, the web is heat-treated at a temperature higher than the melting point of the low-melting point component of the heat-fusible fibers. , fix this morphology. Thereafter, the sheet may be heat-treated by a known calendering method for the purpose of increasing the strength of the sheet, imparting flatness to the surface, and preventing fuzzing due to friction.

Since the density and thickness of the sheet cause differences in the rate of liquid absorption and the amount of liquid retained inside the sheet, it is necessary to adequately control the thickness. As for the thickness, those controlled to a thickness of 0.3 to 0.6 mm (thickness at a load of 20 g/ctA) were excellent in terms of performance and wearing feeling.

(Example) EXAMPLES The present invention will be specifically explained below using Examples.

Example-1 A core-sheath type composite fiber with a core component of polyester and a sheath component of polyethylene was spun, drawn, and treated with a spinning oil, and then treated with various hydrophilic oils using an additional oil method to obtain 2 denier
A hydrophilic raw cotton of 51 sn was obtained. The hydrophilicity evaluation results of this raw cotton are shown in Table 1.

Using this raw cotton, a web of 20 g/lri was obtained by carding. This web was needled using a needle punching machine.

The needle count is 40, and the needle density is 0 to 200 needles/
cI+! Needling was performed with various needle densities.

After needling, this web was heat treated at a temperature of 145'C, and then pressed using hot rolls at 135C with a gap set between the rolls to obtain a top sheet.

This sheet was evaluated by the following method, and the evaluation results are shown in Table 2.

(Evaluation method) (1) Absorption speed and wet bank properties After removing only the top sheet of a commercially available sanitary napkin, a sample was created by placing the sheet prototyped by the above method on top of the napkin, and then applying simulated menstrual blood. The absorption rate and wet back property were evaluated using the following method.

(2) Absorption rate A ring-shaped weight is placed on top of the above sample with the surface sheet placed horizontally, and the sample is leveled and fixed at the same time.

A resin plate with a hole is placed on the center of this sample, and a cylinder with an inner diameter of 20mm is joined to the hole. After injecting 10 ml of simulated menstrual blood at once from this cylinder, the permeation state of the liquid was observed and the time required for complete absorption was measured.

(2) Wet back properties After the completely absorbed sample is left for 10 minutes, a weighed filter paper is placed on top of the sample.

Place an acrylic resin plate and a load on top of this filter paper 15
Leave for a second.

Thereafter, the weight of the filter paper was weighed, and the amount of simulated menstrual blood absorbed into the filter paper was calculated and expressed as ■.

(2) Evaluation of durable hydrophilicity Raw cotton treated with various hydrophilic oil agents was evaluated by the following method.

■ Initial hydrophilicity - 5 g of cotton was prepared and floated on ion-exchanged water at 40'C, and the time taken for it to settle was measured.

(2) Durable hydrophilicity - The cotton ball was immersed in ion-exchanged water for 1 minute, then dried in water and dried (80°C) repeatedly, and then the hydrophilicity was evaluated in the same manner as in (2)-0.

Table-1 Durable hydrophilic raw cotton evaluation results Granted.

Evaluation was made after washing 5 times with water.

As seen in the above results, even if raw cotton has initial hydrophilicity, sheets made from raw cotton that lacks that durability have initial absorbency, but the absorption rate decreases over time, so
It can be seen that it takes time to absorb the simulated menstrual blood.

The surface sheet using durable hydrophilic raw cotton, which is an example of the present invention, is
It can be seen that the absorption rate is fast and the wet banking property is also very good.

It had excellent wear resistance and packability, and also had an excellent feel when worn.

There were also differences depending on the viscosity of the simulated menstrual blood, and it was found that the top sheet according to the present invention exhibited especially excellent performance when a viscous liquid was used.

Example-2 A core-sheath type thermally bonded composite fiber (2dX51+n) whose core component is polyester and sheath component is polyethylene was subjected to hydrophilic treatment by changing the amount of adhesion with an oil agent whose main component is polyhydric alcohol ester. .

This raw cotton was hung on a card to obtain a web with a basis weight of 25 g/m. This web was needled using a needle punching machine under the following conditions, and then heat treated using a hot roller to obtain a sheet. Table 3 shows the results of evaluating sanitary napkins using this sheet as a surface material.

Needling conditions = Needle count 40 Number of needles 30 / crA Table 3 Oil agent adhesion amount and sheet performance The amount of hydrophilic oil agent adhesion is at least 0.2% to at most 1%.
(weight of fiber) is considered to be the limit.

If the amount of adhesion was too large (this resulted in an increased adhesive feeling and poor card passing properties), considering the cost, 0.4 to 0.
．． Approximately 6% is considered to be the optimal condition.

(Effects of the Invention) When sanitary napkins and disposable diapers that use the sheet configured as described above as a surface material absorb blood or urine, the absorption speed up to the absorbent layer is very fast (and It has the ability to completely transfer liquid absorbed into the inner layer of the sheet to the absorbent layer without leaving it in the layer.

In addition, its absorbency is not temporary, and it is capable of absorbing liquid several times, and has the characteristic that its effect can be sustained even when used for a long time.

In sheets using hydrophilic fibers such as rayon, cotton, etc. as the surface sheet material, wet hacking properties are a problem, but sheets using the sheet according to the present invention can exhibit superior performance in wet banking properties as well.

Due to the above-mentioned performance, the top sheet according to the present invention always maintains a dry feeling on the surface of the sheet, and has excellent performance that allows you to enjoy a comfortable wearing feeling for a long time. .

Claims (1)

[Claims] Fabric weight 1 made of heat-fusible composite fiber with durable hydrophilic properties
Needle penetration density is 5~30g/m^2 card web
It is characterized by having through-holes made of fibers arranged in a direction perpendicular to the web surface, which are pierced with needles at a rate of 150/cm^2, and the above-mentioned shape is fixed by heat treatment. Surface sheet for sanitary materials.