JPH0775617B2 - Surface material for sanitary goods - Google Patents

Description

TECHNICAL FIELD The present invention generally relates to a surface material that can be suitably used for sanitary articles such as disposable absorbent articles, and more specifically, sanitary napkins and similar articles. The present invention relates to a surface material comprising two layers, a film layer and a fiber layer, which can be suitably used for sanitary goods such as.

[Conventional technology and its problems]

An absorbent article used for absorbing and holding a liquid from a human body has a structure in which an absorbent body for absorbing and holding the liquid is interposed between a liquid-permeable surface material and a liquid-impermeable leak preventer. It is common knowledge. In this absorbent article, a liquid-permeable surface material (sometimes referred to as an outer packaging material, a covering material, a topsheet, a cover stock, etc.)
Is to quickly transfer the liquid to be absorbed to the absorber (hereinafter referred to as liquid permeability), and to give the human body a dry feeling without returning the liquid transferred to the absorber. (Hereinafter, referred to as liquid return prevention), to shield the color of the liquid diffused in the absorber (hereinafter, referred to as
It is desired to have good texture and the like.

In order to achieve this purpose, various proposals have been made and many improvements have been made.

Specifically, first, a non-woven fabric, which is a hydrophobic fine fiber aggregate, is used as the surface material, and a space of a hydrophobic atmosphere is formed between the body surface and the absorber, so that the liquid permeability is not impaired. A technique for improving the return prevention property (Japanese Patent Laid-Open No. 58-180602) can be mentioned. However, in a non-woven fabric, the liquid to be transferred to the absorber is easily retained in the minute space that is inevitably formed as an aggregate of fibers, and the retained liquid is easily transferred to the body surface when pressure is applied. However, even if a hydrophobic fiber is used, there is a limit in improving the liquid return prevention property.

On the other hand, by using a hydrophobic sheet with open pores as the surface material, a technology for improving the liquid return prevention property (Actual Development Sho 54
-124398, JP 57-1340, JP 61-45753)
Is also proposed.

Certainly, when the perforated hydrophobic sheet is used as the surface material, the retention of the liquid in the surface material does not occur. However, in the perforated hydrophobic sheet, it is necessary to increase the size of the openings in order to give sufficient liquid permeability, and when pressure is applied, the liquid that has transferred to the absorber is easily removed from such large openings. However, it has a drawback that it migrates to the human body surface, and it has been difficult to achieve both liquid permeability and liquid return prevention. In addition, since the absorber is visually observed through the large opening, the shielding property is very poor, resulting in an unpleasant visual discomfort to the user.

Therefore, a hydrophobic perforated film having a tapered capillary structure or a hydrophobic sheet having irregularities with a large number of openings formed in the recesses is used as a surface material to provide a hydrophobic atmosphere between the body surface and the openings. Technology for improving liquid return prevention by forming a space (Japanese Patent Publication No. 57-17081, Japanese Patent Publication No. 55-
No. 32581).

However, in these, at least a part of the bottom of the recess is formed with an opening, and the opening easily comes into contact with the body surface when pressure is applied. Therefore, the liquid return preventing property is hardly improved. Further, the shielding property was not improved to a sufficient level.

From such a background, a surface material comprising a hydrophobic film having a top portion, a bottom portion, and a wall portion connecting them, and at least a part of the wall portion having an opening (hereinafter referred to as a surface material A technique for improving the liquid return prevention property and the shielding property by preventing the contact between the body surface and the opening and blocking the visual observation of the absorber by using a three-dimensional side hole film (Japanese Patent Laid-Open No. Sho 60). −259260) was proposed.

Although these techniques can bring considerable results to the improvement of the liquid return prevention property and the shielding property, they give rise to a new problem that it is difficult to balance the liquid permeability and the texture. That is, in order for the surface material to maintain a predetermined shape and maintain sufficient liquid permeability even when pressure is applied,
It is necessary to use a film made of a resin having a certain degree of rigidity or to increase the thickness of the film to a certain degree to give shape retention, but a surface material made of such a film is tough and has a bad texture. Often becomes.

Since this problem lowers the practical value of the three-dimensional side hole film as a surface material, it is desired to solve the problem as soon as possible.

[Means for solving problems]

As a result of intensive studies to overcome such problems, the present inventors succeeded in creating a surface material composed of a three-dimensional side hole film and a fiber layer, and completed the present invention. It was

That is, the present invention is a surface material in which two layers of a film layer in contact with the skin and a fiber layer facing the absorbent body are integrated,
The film layer is made of an opaque hydrophobic resin having a concave portion composed of a top portion, a bottom portion and a wall portion connecting them, and at least a part of the wall portion is provided with an opening, and
The present invention provides a surface material for sanitary products, which is characterized by having no openings at the bottom.

As can be understood from the above description, the texture of the three-dimensional side hole film can be improved by using a resin having low rigidity or by reducing the thickness thereof, but the liquid permeability is reduced accordingly. In the present invention, by integrating the three-dimensional side hole film and the fiber layer, it has succeeded in improving the shape retention without impairing the texture, and has four properties of liquid permeability, liquid return prevention property, shielding property and texture. It is now possible to obtain a surface material with excellent performance.

Hereinafter, the film layer and the fiber layer in the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of a surface material of the present invention, and FIG. 2 is an enlarged view of an opening portion thereof. Also, from the third
FIG. 5 is an enlarged view of an opening portion showing another embodiment of the surface material of the present invention, and FIG. 6 is a perspective view showing another embodiment of the surface material of the present invention.

According to the present invention, the surface material is formed by integrating the film layer 1 and the fiber layer 2, and the film layer 1 is an opaque hydrophobic material having a concave portion 5 composed of a top portion 3, a bottom portion 4 and a wall portion connecting them. Any material may be used as long as it is made of a resin and has an opening 6 provided at least in a part of the wall portion 5 and that there is no opening in the bottom portion 4. However, considering liquid permeability, It is preferable that the wall where the aperture is present is not covered by the top. Further, in consideration of the liquid return prevention property, as shown in FIG. 7, the plane formed by the wall portion 5 having the opening and the top portion 3 connected to the wall portion are not present, and the angle α between the plane surface is smaller than a right angle, and It is more preferably 20 ° or more. In the film layer, when the angle α (hereinafter referred to as an inclination angle) between the plane formed by the wall portion having the aperture and the plane formed by the apex continuous with the wall portion having the aperture is larger than a right angle. However, no matter how the shape retention is improved by integration with the fiber layer, it becomes difficult to maintain the prescribed shape when a very large pressure is applied. Occurs. On the other hand, when the inclination angle is less than 20 °, the surface material has substantially no three-dimensional shape, and the liquid return prevention property and the shielding property are deteriorated.

Further, the openings 6 may be present in the top portion 3 as shown in FIG. 6, but in consideration of the liquid return prevention property and the shielding property, the total number of the openings 60 is 50.
% Or more is preferably present in the wall portion 5, and it is more preferable that all open holes are present in the wall portion.

In the present invention, the apertures of the film layer can be freely provided in a well-balanced range of liquid permeability, liquid return prevention property and shielding property, but generally the size of the aperture is 0.1 to 2 mm.
It is preferable that the density is ² , and the density of the openings is 10 to 100 holes / cm ² .

In the present invention, the film layer is required to be opaque in order to impart sufficient shielding properties to the surface material. When the film layer is opaque, the surface material of the present invention is also opaque and can be preferably used as a surface material of an absorbent article that absorbs a colored liquid such as menstrual blood. The opacity of this surface material is quantified as whiteness (see Examples), and the whiteness is preferably 10% or more. Various methods are conceivable as a method for imparting opacity. For example, a method of adding a white pigment to the resin in the film manufacturing process, a method of coating the film surface with a white pigment mixed with a suitable binder, and the like, but if the desired opacity can be imparted to these methods, Any method may be used without limitation.

As the resin forming the film layer, any resin may be used as long as it is hydrophobic. For example, polyolefins, olefins and other monomers (vinyl acetate, ethyl acrylate, etc.)
Copolymer resins, synthetic resins such as polyester, nylon, and acetate, and blended polymers of these, but considering the texture and processability in actual production, polyolefins, copolymer resins of olefins and other monomers, or blends of these. Polymers are preferable, and low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer or blends thereof are more preferable.

The thickness of the film layer can be much smaller than that of the three-dimensional side hole film alone, but in consideration of the texture and the shielding property, it is generally preferably 3 to 50 μm, and 10 to 40 μm. More preferable.

Further, as a means for controlling the liquid permeability and the liquid return prevention property, the surface of the film layer is made hydrophilic by coating with a surfactant, physical treatment such as plasma irradiation or chemical treatment such as mineral acid treatment. The surface of the film layer can be treated to be water-repellent by coating with a silicone-based or fluorine-based agent.

In addition, the film layer may be subjected to calendering treatment or embossing treatment with a fine pattern, if necessary for improving the texture.

On the other hand, in the present invention, the fibrous layer means a so-called web formed by lightly entangled fibers, or a so-called non-woven fabric or paper in which fibers are fixed by entanglement or adhesion.

Any fiber composition can be used. However, in consideration of the shape retention of the surface material, it is preferable to contain 50% by weight or more of synthetic fibers such as polyolefin, polyester, acryl and polyamide. Among these, polypropylene, polyester, polyethylene / polypropylene composite fiber, polyethylene / polyethylene composite fiber, and low melting point polyester / polyester composite fiber are particularly preferable because they are particularly elastic and easy to form a stable texture. When synthetic fibers are used, it is preferable that the surface of the fibers is subjected to a hydrophilic treatment by an appropriate method in consideration of liquid permeability. The thickness of the fibers is preferably in the range of 1 to 10 denier in consideration of liquid permeability and texture.

The basis weight of the fiber layer can be freely determined within a range in which the surface material has sufficient shape retention and has a good texture.
Preferably generally it is ^{5~100g / m 2, 10~50g / m} 2
It is more preferable if

Typical methods for producing the surface material of the present invention are roughly classified into the following two.

The first is a method in which a film having no holes and a fiber layer are first integrated with each other by heat bonding or an adhesive and then perforated. It can be said that this method is advantageous in terms of productivity as compared with the following method in that it is possible to use a so-called laminated film which is obtained by integrally extruding the raw material resin with the fiber layer in the step of melt-extruding the raw material resin.

The second is a method in which a film having no holes is first pierced into a three-dimensional side hole film and then integrated with the fiber layer. Examples of the integration method include thermal adhesion, adhesion with an adhesive, and entanglement with an air stream or a high-pressure water stream.

The film layer and the fiber layer only need to be integrated so that they do not peel off when mounted, and when they are integrated by adhesion,
The adhesion points may be evenly distributed on the boundary surface or may be in a pattern.

The surface material of the present invention is not limited to the examples described in detail, and various modifications can be made within the range defined above.

〔Example〕

Hereinafter, how useful the present invention is will be described with reference to specific examples, but the present invention is not limited to these examples.

Examples 1 to 45 and Comparative Examples 1 to 5 By using the film layers shown in Tables 1 and 2 and the fiber layers shown in Table 3 as constituent materials, various surface materials shown in Tables 4 to 7 were prepared. It was made by the method.

The methods for measuring the physical properties of each constituent material and surface material will be described below. Each physical property value is an average value of 10 measured values.

(1) Method of measuring physical properties of constituent materials Film layer i) Size of opening: An enlarged photograph of the opening surface viewed from the vertical direction is taken using a stereoscopic microscope, and the size of the opening on the photograph is taken. The value a was measured using a planimeter, and the size A of the actual aperture was calculated by the equation (1).

A (mm ² ) = a (mm ² ) / x ² (1) x: Magnification of photograph relative to actual product ii) Density of open pores: Measured by counting the number of open pores per 1 cm ^{2 of} surface material.

iii) Inclination angle and wall thickness: A cross section of the surface material was photographed as shown in FIG. 7, and the angle indicated by α was measured with a protractor, and this was taken as the inclination angle.
Further, the wall thickness t on the photograph was measured using a ruler, and (2)
The actual wall thickness T was calculated by the formula. When the surface material has a curved shape, as shown in FIG. 8, the angle of intersection between the tangent line l ₁ at the top of the top and the straight line l ₂ passing through both ends of the opening is defined as the inclination angle α.

T (μm) = 1000 t (mm) / x (2) x: Magnification of photograph relative to the actual product iv) Whiteness: Measured using ND-101DP type color difference meter manufactured by Nippon Denshoku Industries Co., Ltd. . First, after calibrating so that the reflectance of the standard white plate (barium sulfate) for light with a wavelength of 500 nm (green) is 100%, measure the reflectance of each surface material sample for light with the same wavelength, This was defined as whiteness. The detailed operation method was based on the "101DP type instruction manual".

 Fiber layer i) Weighing: The weight of the fiber layer was measured to calculate the weighing.

(2) Method for measuring physical properties of surface material For evaluation, instead of removing the surface material of a commercially available sanitary napkin "Laurier" (manufactured by Kao Co., Ltd.), each surface material was constituted, and this was used as a sample napkin as follows. It evaluated by the method.

Absorption time and amount of fluid returned: 10 g of horse defibrinated blood was injected into a sample napkin sample under a pressure of 5 g / cm ² , and the time required for absorption was defined as the absorption time. In general, the smaller the absorption time, the better the liquid permeability of the surface material. Then, after a certain period of time, the pressure was increased to 50 g / cm ² , and the amount of the test liquid returning from the inside through the surface material was measured and defined as the liquid return amount. The smaller the amount of this liquid returned, the less sticky the surface is and the better the usability is.

Texture: The feel of the assumed napkin sample when touched by hand is classified into the following three ranks.

Grade 3: Very soft.

Grade 2: Soft.

Grade 1: Hard and unsuitable as a surface material.

Visual dryness: The state after absorbing 4 g of horse defibrinated blood in the assumed napkin sample was classified into the following four ranks.

Grade 4: No red color of blood is observed.

Grade 3: Only a slight red color of blood is observed.

Grade 2: Red blood is slightly recognized.

1st grade: Red color of blood is noticeable as it causes discomfort.

Note) LDPE: Low-density polyethylene (Mitsui Petrochemical Co., Ltd.) EVA: Ethylene-vinyl acetate copolymer (Mitsui Petrochemical Co., Ltd.)
Tufmer: ethylene-α-olefin copolymer (manufactured by Mitsui Petrochemical Co., Ltd.) Blend: LLDPE-LDPE-Tuffmer blend A-2: Opening is present at a ratio of wall / top = 70/30.

A-3: There are openings at a ratio of wall / top = 30/70.

A-4: Full opening exists only at the bottom.

B-2: The surface was hydrophilized by applying a surfactant (Perex OTP manufactured by Kao Corporation).

B-3: Surface hydrophilic treatment was performed by plasma irradiation under argon gas.

B-4: A surface water repellent treatment was performed by applying a fluorine-based water repellent (“Bosui” manufactured by Sony Chemicals Co., Ltd.).

Note) II-1 to 6: After making a web using a miniature card of a predetermined fiber, it was treated with hot air.

II-7: After making a web using a miniature card of a predetermined fiber, it was subjected to a high-pressure water stream treatment.

II-8: Asahi Kasei Co., Ltd. "IIL" II-9: Nimura Kagaku Co., Ltd. "Taiko TCF" II-10: Claflex Co., Ltd. "Counter Cloth" II-11: Ino Paper Co., Ltd. Bix "II-12: Ino Paper Co., Ltd. II-13: PALBU was used as a web by the air lay method.

II-14, 15: A predetermined fiber was made into a web using a miniature card.

ES: Polyethylene / polypropylene composite fiber (manufactured by Daiwa Spinning Co., Ltd.) SH: Polyethylene / polyester composite fiber (manufactured by Daiwa Spinning Co., Ltd.) PET: Polyester fiber (manufactured by Teijin Ltd.) Ray: Racon fiber (manufactured by Daiwa Spinning Co., Ltd.) )) Surface hydrophilic treatment: Perex DPT (Kao Corporation) on the fiber layer
5% by weight) was applied.

Note) C-2: After forming an opening of the shape shown in FIG. 2 in the film layer alone with an embossing roller, the fiber layer was fixed by heat bonding.

C-3: The film layer alone was formed with an embossing roller to form openings having the shape shown in FIG. 2, and then the fiber layer was fixed with an adhesive.

C-4: The film layer alone was formed with an embossing roller to form openings having the shape shown in FIG. 2, and then the fiber layer was fixed by air pressure.

C-5: The film layer alone was formed with an embossing roller to form holes having the shape shown in FIG. 2, and then the fiber layer was fixed with a high-pressure water stream.

As shown in Examples 1 to 45, the surface material of the present invention has a short absorption time and a small amount of liquid reversion, has a good visual dryness, and has an excellent texture. In particular, Examples 1, 2 satisfying all the claims 2 to 6,
Nos. 6, 7, 10-12, and 14-33 have a particularly high level in terms of liquid return prevention property and visual dryness, and can be said to be exactly ideal surface materials.

In Comparative Examples 1 and 2, the three-dimensional side hole film is used alone as the surface material without integrating the fiber layers. Comparative Example 1
Has a good texture because the film layer has a small thickness, but has poor shape retention at the time of pressurization and easily closes the pores, resulting in poor liquid permeability. On the contrary, in Comparative Example 2,
Since the thickness of the film layer is large, the shape retention is high and the liquid permeability is good, but it is hard and the texture is bad.

In Comparative Example 3, the nonwoven fabric, which is the fiber layer, is used alone as the surface material without integrating the three-dimensional side hole film, but as described above, the liquid is very likely to be retained in the fiber gap of the nonwoven fabric. , Liquid return prevention and visual dryness are poor.

In Comparative Example 4, since all the openings are present only at the bottom, the liquid return prevention property and the visual dryness are poor, and Comparative Example 5
Since the film layer does not contain a white pigment and has a low whiteness, the color of the liquid diffused in the nonwoven fabric layer or the absorber can be seen through, and thus the visual dryness is poor.

Therefore, it must be said that the materials shown as comparative examples are all extremely insufficient as surface materials.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the surface material of the present invention, and FIG.
The drawing is an enlarged view of the hole portion, FIGS. 3 to 5 are enlarged views of the hole portion of another embodiment of the surface material of the present invention, and FIG. 6 is another embodiment of the surface material of the present invention. FIG. 7 is a perspective view, and FIGS. 7 and 8 are views showing a method for measuring the inclination angle and the wall thickness of the film layer. 1: Film layer, 2: Fiber layer 3: Top part, 4: Bottom part 5: Wall part, 6: Open hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-60-259260 (JP, A) JP-A-60-259261 (JP, A) JP-B 57-17081 (JP, B2) Nikkei New Material No. 54 Issue November 28, 1988 Issued by Nikkei BP, pages 40-53

Claims (6)

[Claims] 1. A surface material in which two layers of a film layer in contact with the skin and a fiber layer facing the absorbent body are integrated, and the film layer is composed of a top portion, a bottom portion and a wall portion connecting them. Made of opaque hydrophobic resin with concave parts
A surface material for a sanitary article, characterized in that at least a part of the wall portion has an opening, and the bottom portion has no opening. 2. The surface material for a sanitary article according to claim 1, wherein in the film layer, a wall portion having an opening is not covered with a top portion. 3. In the film layer, when an angle between a plane formed by a wall portion having an opening and a plane formed by a top portion connected to the wall portion is measured from a position on the plane surface formed by the top portion where a film does not exist, The surface material for a sanitary article according to claim 1, wherein the surface material is smaller than a right angle and is 20 ° or more. 4. The film layer according to claim 1, wherein the size of the openings is 0.1 to ² mm ² and the density of the openings is 10 to 100 holes / cm ^2. Surface material for sanitary goods. 5. The surface material for a sanitary article according to claim 1, wherein the film layer is made of polyethylene or a copolymer of ethylene and another monomer. 6. The surface material for a sanitary article according to claim 1, wherein the fiber layer contains 50% by weight or more of synthetic fibers.