JP2594327B2 - Sanitary goods surface materials - Google Patents

Description

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 particularly, sanitary napkins and similar articles. The present invention relates to a surface material that can be suitably used for sanitary articles such as the above.

[Conventional technology and problems]

An absorbent article used to absorb and hold liquid from the human body has a structure in which an absorber that absorbs and holds liquid is interposed between a liquid-permeable surface material and a liquid-impermeable leakproof material. Being known is known. In this absorbent article, a liquid-permeable surface material (sometimes referred to as an outer packaging material, a covering material, a tope sheet, a cover stock, etc.)
Is to promptly transfer the liquid to be absorbed to the absorber (hereinafter referred to as liquid permeability) or to give the user a dry feeling without reversing the liquid transferred into the absorber (this Hereinafter, referred to as liquid return prevention)),
Close contact with the user's skin to prevent leakage caused by the flow of liquid on the surface (hereinafter referred to as "adhesion"), and to shield the color of the liquid diffused in the absorber (hereinafter referred to as "shielding"). It is demanded that the texture is good.

Recently, a hydrophobic film provided with apertures has excellent shielding properties. Therefore, instead of a nonwoven fabric which is a fiber aggregate conventionally used in general, a technique of using it as a surface material (Japanese Patent Publication No. Sho 57-17081) , JP-A-60-259260, JP-A-6
Many publications, such as the publications of 1-45753, have been proposed.

Indeed, if a perforated hydrophobic film is used as the surface material, no liquid is retained in the surface material, so that the shielding property is considerably improved. However, these porous hydrophobic films have poor adhesion, which has the undesirable consequence of frequent leakage caused by the flow of liquid on the surface.

As described above, there was no conventional surface material having both excellent shielding properties and adhesion properties, and it was not possible to obtain a sanitary article having a good feeling in use and sufficient leakproofness.

[Means for solving the problem]

The present inventors have conducted intensive studies to overcome such problems, and as a result, have completed the present invention.

That is, the present invention comprises a hydrophobic film having a plurality of concave portions 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. The wall part where is present is not covered with a top part, and provides a surface material for sanitary goods characterized by having a strain in the thickness direction under a pressure of 50 g / cm ² of 40% or more. is there.

Conventional hydrophobic films have poor deformability in the thickness direction, and have poor adhesion because a gap is formed between the absorbent article and the body surface of the wearer as the user drives. Therefore, the present inventors, by using a perforated film rich in deformability in the thickness direction to improve the adhesion, to maintain excellent shielding properties, and to surprisingly improve leakproofness. succeeded in. This thickness-wise deformability is generally due to the fact that the stress in the thickness direction generated on the surface material during use of the absorbent article is usually 50%.
Since it is about g / cm ^2, it is quantified as a strain in the thickness direction under a pressure of 50 g / cm ² (hereinafter, referred to as a compressive strain; see the examples for the measuring method). In order to provide sufficient adhesion, it is necessary that the compression strain is 40% or more, but under any conditions (for example, when the wearer exercises vigorously), sufficient adhesion is exhibited. In order to achieve this, the content is preferably 50% or more.

The surface material used in the present invention means a hydrophobic film alone or a hydrophobic film and a maintenance layer integrated on at least one surface thereof, but in the latter case, the surface material is formed into an absorbent article as a surface material. In that case, any layer may be used as the surface, that is, the surface in contact with the body surface. In general, it is preferable to use a film on the surface when emphasizing the shielding property, and to use the maintenance layer on the surface when emphasizing the touch. It is also possible to integrate a fiber layer on both sides of the hydrophobic film.

The hydrophobic film and the fiber layer will be described in detail below.

FIG. 1 is a perspective view showing one embodiment of the surface material of the present invention, and a hydrophobic film 1 is provided with a large number of openings by embossing. FIG. 2 is an enlarged view of the opening.

As shown in FIGS. 1 and 2, the shape of the film layer 1 has a top portion 3, a bottom portion 4, and a wall portion 5 connecting them, and an opening 6 exists in at least a part of the wall portion 5. , Opening 6
Is preferably not covered with the top 3. That is, the top portion 3 is a portion constituting the main portion of the film layer 1, and a large number of concave portions composed of the bottom portion 4 and the wall portion 5 are formed over the entire surface of the film layer 1 by embossing. . The wall 5 where the opening 6 exists is not covered by the top 3 means that the opening 6 can be seen without being covered by the top 3 when viewed from above the film layer 1, that is, in FIG. The angle α between the top 3 and the wall 5 is
Means less than 90 ゜. With such a shape, the wall portion is easily deformed by the stress, so that the compressive strain is increased and the adhesion is improved. On the other hand, a shape in which the opening 6 is provided only in the bottom portion 4 as shown in FIG. 3 is not preferable because the wall portion is hardly deformed and it is difficult to increase the compression strain. In the case where the wall portion 5 having the opening as shown in FIG. 4 is covered with the top portion 3, that is, when α is 90 ° or more, the opening becomes cold when pressure is applied. For this reason, the liquid permeability is reduced, which is not preferable. Furthermore, in consideration of the shielding property and the liquid return preventing property, the top part, the bottom part and the wall part connecting them are provided, and at least a part of the wall part has an opening, and the wall part where the opening exists is located at the top part. In addition to being uncovered, the angle α between the plane formed by the opening and the plane formed by the top formed continuously with the wall where the opening exists (hereinafter referred to as the inclination angle. (See Examples) is preferably 20 ° or more. When the inclination angle is smaller than 20 °, the surface material substantially has no three-dimensional shape,
It is not preferable because the shielding property and the liquid return prevention property decrease. The angle α is preferably 20 to 80 °, more preferably 40 to 80 °
゜.

It should be noted that by providing irregularities irrelevant to the openings in the film having the openings, the compressive strain can be increased and the leakproofness can be improved.

The thickness of the film layer is preferably as thin as possible in order to provide sufficient adhesiveness. However, if the thickness is too small, it is difficult to provide sufficient shielding properties. 10 ~
It is preferably 100 μm, and preferably 5 to 50 μm when used integrally with the fiber layer.

As the resin forming the film layer, any resin may be used as long as it is hydrophobic. For example, polyolefin, olefin and other monomers (vinyl acetate, ethyl acrylate, etc.)
Copolymer resins, polyurethane, polyester, nylon, acetate and other films and blended polymers thereof, and the like, when considering the adhesion,
Polyethylene resins such as low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer or a blend thereof are preferably used because of their high flexibility. Can be

The film layer is preferably opaque in order to impart sufficient shielding properties to the surface material. If the film layer is opaque, the surface material of the present invention becomes 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 (refer to Examples for the measuring method), and the whiteness is preferably 20% or more. Note that various methods can be considered as a method for improving the opacity. For example, a method in which a white pigment is added to a resin in a film production process, a method in which a white pigment is mixed with an appropriate binder on a film surface and applied, and the like. Any method may be used without limitation.

The aperture shape can be freely set within a range in which the liquid permeability and the shielding property are balanced.In general, the aperture size is 0.1 to ² mm2, and the density of the aperture is a film layer. Is preferably 10 to 100 / cm ² with respect to the total area of However, the size and density of the apertures need not always be constant, but can be changed regularly or irregularly as needed. For example, the size or density of the apertures can be increased in the central portion of an absorbent article that requires particularly high liquid permeability.

The apparent thickness of the surface material, that is, the distance between the top and the bottom, can be arbitrarily determined within a range that provides a sufficient liquid return prevention property, and is usually 0.1 to 5 mm. The shape of the bottom and the wall of the embossed concave portion can be arbitrarily selected, but a pyramid or a cone is suitable. The number of recesses is preferably 5
50 pieces / cm ² .

Further, as a means for controlling the liquid permeability and the liquid return preventing property, physical treatment such as blending of a hydrophilic agent to the resin of the film, application of a surfactant to the film surface, plasma irradiation, or mineral acid treatment. It is possible to hydrophilize the surface of the film layer by applying a chemical treatment such as a hydrophobization treatment to the surface of the film layer, or by applying a silicon-based or fluorine-based chemical to the surface of the film layer. It is possible.

It is also possible to subject the film layer to a calendering process or a fine pattern embossing process as necessary to improve the texture.

On the other hand, the fiber layer is indicated by 2 in FIGS. 1 to 7, and is a so-called web composed of lightly entangled fibers, a so-called nonwoven fabric or paper formed by fixing fibers by entanglement or adhesion. Although it is possible, a nonwoven fabric or paper is preferable in consideration of liquid permeability, and a nonwoven fabric is more preferable in consideration of adhesion, and a so-called dry heat-bonded nonwoven fabric in which fibers are fixed by heat fusion is further preferable. preferable. In the web, the fibers are not fixed to each other, and the fiber layer is easily broken by the motion of the user, so that the liquid permeability may be reduced. Further, the paper is hard to break because the fibers are fixed to each other, but generally has poor flexibility, so that it is difficult to impart sufficient adhesion to the surface material. On the other hand, in a nonwoven fabric, especially a dry heat-bonded nonwoven fabric, the fibers are firmly fixed to each other, and since the fibers are rich in flexibility, the liquid permeability, liquid return prevention and adhesion are very excellent. A surface material is obtained.

In addition, the fiber layer can have a structure in which the composition is discontinuously different in the thickness direction, but in this case, if the fibers are arranged so that the hydrophilicity increases as the distance from the film layer increases, It is more preferable because the liquid permeability and the shielding property are improved.

Various fibers can be used as the constituent fibers of the fiber layer. For example, hydrophilic fibers such as wood pulp, rayon, and piniron, and hydrophobic fibers such as polyolefin, polyester, acrylic, and polyamide can be used.However, in consideration of shielding properties, hydrophobic fibers are mainly used. preferable. Considering that the fiber layer is preferably a heat-bonded dry nonwoven fabric as described above, among these hydrophobic fibers, polyethylene / polypropylene composite fibers, polyethylene / polyester composite fibers, and low-melting polyester / polyester composite fibers , Etc. are more preferable, and in consideration of the adhesiveness to the film layer, polyethylene / polypropylene conjugate fibers and polyethylene / polyester conjugate fibers are more preferable. In the case of hydrophobic fibers, if further improvement in liquid permeability is required, an appropriate hydrophilic treatment or water repellency treatment can be performed, and further improvement in shielding properties is required. In such a case, fibers having a modified cross section such as a multi-lobed shape may be used.

The fineness of the fiber is generally more preferably in the range of 1 to 10d, in consideration of the liquid return preventing property and the texture.
More preferably, it is 1.5 to 6d.

In general, the basis weight of the fiber layer is preferably 5 to 100 g / m ² in consideration of the liquid return prevention property and texture, and 10 to 50 g.
/ m ² is more preferable.

Further, considering the liquid permeability, the density of the fibers in the fibrous layer is preferably lower at the opening of the hydrophobic film than at the non-opening, and at least 50% of the area of the opening of the hydrophobic film. Is more preferably not present at all.

It is preferable that the film and the fiber layer are integrated as tightly as possible in consideration of the liquid permeability and the property of preventing liquid return, and it is generally preferable that the peel strength of both is 50 g or more. In the case of performing integration by bonding, the bonding points may be uniformly distributed on the boundary surface or may be in a pattern.

A typical method of integrating a hydrophobic film and a fiber layer is roughly classified into the following two methods.

The first is a method in which a film having no holes and a fiber layer are first integrated by heat bonding, an adhesive, or the like, and then the holes are perforated. This method is advantageous in that the density of the fibers in the fiber layer at the opening of the film is necessarily lower than that at the non-opening, and is integrated with the fiber layer in the step of producing a film by extruding the raw resin. It can also be said that it is advantageous from the viewpoint of productivity as compared with the following method in that a so-called laminate film obtained by conversion can be used.

The second is a method in which a film having no holes is perforated by itself to form a perforated film, and then integrated with a fiber layer. As a method of integration, bonding can be performed by heat bonding or bonding with an adhesive, or by entanglement with an air flow or a high-pressure water flow when the openings are relatively large in density.

When it is necessary to impart particularly high liquid permeability, a sheet-like material such as a nonwoven fabric or a web made of hydrophilic fibers such as a pipe or rayon is adhered to the surface of the surface agent with a thermal adhesive or an adhesive. Alternatively, in the first method, the hydrophilic fiber sheet can be integrated by superposing and perforating the hydrophilic fiber sheet.

The absorbent article of the present invention is not limited to the examples described in detail, but can be variously modified within the range specified above.

〔Example〕

Hereinafter, the usefulness of the present invention will be described with specific examples, but the present invention is not limited to these examples.

Various surface materials according to the present invention or comparative surface materials having the constitutions shown in Table 1 were produced, and their performance was evaluated by the following methods.

 The results are shown in Table 1.

In Examples 1 and 2 and Comparative Examples 1 and 3, a surface material was produced by embossing holes in a film made of a predetermined resin. In Examples 3 to 6 and Comparative Examples 2 and 5, a predetermined film resin was laminated on a fiber layer made of a predetermined heat-bonded nonwoven fabric, and then embossed holes were formed. Comparative Example 6
Then, after slitting a sheet made of a predetermined resin as shown in FIG.
The surface material was produced by integrating the above-mentioned material and the fiber layer 2 by embossing. Further, in Comparative Example 4, only the fiber layer was used as the surface material without performing the opening process.

For evaluation of absorption time, liquid return amount, dynamic absorption amount and visual dryness, a commercially available sanitary napkin “Rollier” was used.
The surface material (manufactured by Kao Corporation) was removed, and each surface material was formed instead, and this was evaluated as a napkin assumed sample. However, in Examples 3 to 6 and Comparative Examples 2, 5, and 6, the surface material was configured such that the fiber layer was in contact with the absorber side. In addition, each physical property value is an average value of ten measured values.

(1) Constituent material Film layer i) Size of aperture: An enlarged photograph of the aperture surface viewed from its vertical direction was taken using an electron microscope, and the size a of the aperture on the photograph was measured using a planimeter. The size A of the actual aperture was calculated by the equation (1).

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

iii) Inclination angle and thickness: A cross section of the surface material was photographed as shown in FIG.
Was measured with a protractor, and this was defined as the inclination angle. Also, the thickness t ₁ on the photograph was measured using a ruler,
(2) to calculate the thickness T ₁ of the real thing by the formula. The surface material when it has a curved shape, as shown in FIG. 7, and an inclination angle α of the crossing angle of the straight line l ₂ passing through both ends of the tangent l ₁ and openings 6 at the top 3 upper .

T ₁ (μm) = 1000 t ₁ (mm) / x (2) iv) Whiteness: The measurement was performed using a colorimeter ND-101DP manufactured by Nippon Denshoku Industries Co., Ltd. First, after calibrating the reflectance of the standard white plate (barium sulfate) to the light of the wavelength of 500 nm (green) to be 100%, the reflectance of each surface material sample to the light of the same wavelength is measured. It was defined as whiteness. In addition, the detailed operation method conformed to "101DP type instruction manual".

 Fiber method i) Basis weight: The basis weight was calculated by measuring the weight of the fiber layer.

(2) Surface material Compressive strain:-Test piece: The surface material was cut into a square of 100 mm square and subjected to measurement.

-Measuring method: Tensilon RTM-25 type (manufactured by Toyo Baldwin Co., Ltd.) was used. First, as shown in FIG. 8A, a pressure receiving plate 8 having a diameter of 30 mm is attached to the tip of a 5 kg load cell 7 for compression (hereinafter referred to as a cell), and then, as shown in FIG. Gently contact the sample table 9 and 5kg
Apply a load of. At this time, the distance between the pressure receiving plate and the sample stage is set to 0. Next, the cell is raised by 9 mm. Then, as shown in FIG. 8 (c), the test mold 10 is placed face up on the sample table 9, the cell is lowered, and the load applied to the test piece is recorded on a recording paper. The measurement conditions are as follows.

Cell lowering speed: 3 mm / min Recording paper full scale: 500 g Recording paper scanning speed: 300 mm / min Calculation method: The compression load recorded on the recording paper is as shown in FIG. In this recording sheet, the cell lowering start time A
, The distance d ₁ (mm) from the point at which the cell comes into contact with the test piece and the load starts to be applied, and the load of 350 g (this is 50 g / cm ²
The distance d ₂ (mm) until the point C when the pressure
Is measured with a ruler, and the apparent thickness of the sample is calculated by equation (3).
Calculate t ₂ (mm), and further calculate the compressive strain ε (%) at 50 g / cm ² by equation (4).

t ₂ = (900−d ₁ ) / 100… (3) ε = (d ₂ −d ₁ ) / t ₂゜… (4) Absorption time and liquid return amount: 10 g of test solution was added to a napkin assumed sample at 5 g / cml. _The injection was performed under the pressure of ₂ , and the time required for absorption was defined as the absorption time.
Generally, the shorter the absorption time, the better the liquid permeability. Further, after a certain period of time, the pressure was increased to 50 g / cm ² , and the amount of the test liquid returning from inside through the surface material was measured, and the amount was referred to as a liquid return amount. The smaller this liquid return amount is,
It shows that it has excellent liquid return prevention.

Visual dryness: The state after blood was absorbed by the napkin assumed sample was classified into the following three categories.

Grade 3: No red blood is observed.

Second grade: Only a slight red color of blood is observed.

Grade 1: The red color of the blood is remarkably recognized with discomfort.

Dynamic absorption: movable female waist model 11 as shown in FIG. 10 (a)
Next, as shown in FIG.
When the test solution is to be injected from the tube 13 while continuing the running motion after the start, the injection amount of the test solution at the time when the leak is confirmed is defined as the dynamic absorption amount. The larger the dynamic absorption amount is, the more excellent the leakproof property is.

(Note) LLDPE: Linear low-density polyethylene LDPE: Low-density polyethylene EVA: Ethylene-vinyl acetate copolymer Film layer: Pore size: 0.10 mm ² Pore density: 30 holes / cm ² Slope angle: Approx. 60 ° (Examples 1 to 6, Comparative Examples 1 and 2) Approximately 0 ° (Comparative Example 3) Approximately 120 ° (Comparative Example 5) Fiber layer: heat-bonded nonwoven fabric having the following composition However, NBP: surface hydrophilic treated polyethylene / polypropylene composite fiber (manufactured by Daiwa Spinning Co., Ltd.) SH: surface hydrophilic treated polyethylene / polyester composite fiber (manufactured by Daiwa Spinning Co., Ltd.) [Effects of the Invention] Examples 1 to 6 As shown in the surface material of the present invention,
The absorption time and liquid return amount are short and the visual dryness is good, and the adhesiveness is also excellent, so that the dynamic absorption amount is large and the leakproofness is high.

On the other hand, in Comparative Examples 1 to 3, since a film having a small compression strain is used, the dynamic absorption is low and the leakproofness is poor. Further, in Comparative Example 4, the nonwoven fabric was used alone as the surface material, and although the adhesion was good, the liquid was very easily retained in the fiber gap of the nonwoven fabric as described above. Very poor visual dryness. In Comparative Example 5, since the wall having the opening is covered with the top, the absorption time is long and the liquid permeability is poor. Comparative Example 6
In this case, since there is no specific opening as in the present invention, the amount of reversion is larger than that of the present invention, and the visual dryness is slightly inferior.

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

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a surface material of the present invention, and FIG.
FIG. 3 is an enlarged view of an aperture of one embodiment of the present invention, FIG. 3 is an enlarged view of an aperture of a conventional surface material, FIG. 4 is an enlarged view of an aperture for comparison, and FIG. 6 is a perspective view of a surface material for comparison, FIG. 6 and FIG. 7 are diagrams showing a method of measuring the inclination angle and thickness of the film, FIG. 8 and FIG. FIG. 10 is a diagram showing a method for measuring the amount of dynamic absorption. 1: Film, 2: Fiber layer 3: Top, 4: Bottom 5: Wall, 6: Opening 7: Cell, 8: Pressure plate 9: Sample table, 10: Sample 11: Female waist model 12: Napkin assumed sample 13: Tube

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-52-123745 (JP, A) JP-A-61-45753 (JP, A) JP-A-60-259260 (JP, A) 2363 (JP, B2) JP 7-75616 (JP, B2)

Claims (2)

(57) [Claims] 1. A hydrophobic film having a plurality of concave portions composed of a top portion, a bottom portion and a wall portion connecting them, wherein at least a part of the wall portion is provided with an opening,
The wall with the aperture is not covered by the top and 50g /
A surface material for sanitary goods, characterized in that the strain in the thickness direction under a pressure of cm ² is 40% or more. 2. The surface material for sanitary goods according to claim 1, wherein a fiber layer is integrated on at least one surface of the hydrophobic film.