JPH0255058A - Surface material for absorptive article - Google Patents

Abstract

PURPOSE:To obtain the excellent absorption performance and adhesive property by finishing the center section of a surface material as bulky as possible, setting the thickness of both side portions containing the cutoff face of the surface material 2/3 or below of the thickness of the center section, and making the weighing capacities of the center section and both side ends practically same. CONSTITUTION:Portions from both side ends of a surface material 6 to the inside by 10mm or more are made thinner than the center section to give the necessary adhesive property to a surface material 6. All the portions other than the portion of the usage face of an absorptive article are made thin in thickness. The necessary adhesive property can be given if the thickness of both side sections of the surface material 6 is made 2/3 or below of the thickness of the center section of the surface material 6, the more sufficient adhesive property is given if it is 1/2 or below. The pressurizing and compressing processing of the surface material 6 with a roller or the like is the easiest method to reduce the thickness of side sections. It is necessary to make weighing capacities of the center section and both side sections practically same.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to surface materials for absorbent articles having high absorbent performance and adhesive properties, particularly for absorbent articles such as sanitary napkins, disposable diapers, and incontinence pads. This invention relates to surface materials for sexual articles.

[Conventional technology and issues to be solved]

Conventional absorbent articles, such as sanitary napkins or disposable diapers, basically consist of an absorbent body made of a cotton-like bulb, absorbent paper, etc., a leak-proof material placed on the bottom and sides of the absorbent body, and a surface placed on the top side. Made of wood.

In recent years, with rapid technological advances, efforts have been made to improve absorption performance by introducing new materials such as absorbent polymers and hydrophobic surface materials.

However, even absorbent articles made of combinations of materials that individually have excellent performance cannot be said to fully demonstrate their original performance during actual use. It is also clear that crotch leakage remains a user's number one complaint with such absorbent articles.

The major cause of this leakage is that irregular stress is applied to the absorbent article due to movement of the user's groin area, causing separation of the constituent materials and wrinkles in the absorbent article. Among these materials, the surface material in particular receives a large amount of stress because it comes into direct contact with the user's skin, and is easily separated from the leak preventive material and absorbent material, so it is strongly desired that these materials be bonded together by some method.

However, it must be said that the adhesive properties of conventional surface materials are extremely insufficient. This is thought to be because conventional surface materials were designed with only absorption performance in mind.

In other words, the surface material that comes into direct contact with the user's skin must not only allow the liquid to be absorbed to quickly transfer to the absorbent body (hereinafter referred to as liquid permeability), but also ensure that the liquid that has migrated into the absorbent body is It is desired to prevent liquid from returning to the surface (hereinafter referred to as liquid return prevention property) and to have a good texture. In order to achieve sufficient liquid permeability, it is preferable to impart a high degree of porosity to the surface material, and in order to achieve sufficient liquid return prevention properties, a hydrophobic material should be used and the surface material should have a high degree of porosity. It is preferable to increase the apparent thickness of the absorbent material and provide a hydrophobic space between the absorbent material and the user's skin. For these reasons, in recent years, hydrophobic materials having a high degree of bulk and porosity, such as nonwoven fabrics made of synthetic fibers and embossed perforated films made of synthetic resins, have come into widespread use.

However, when the bulkiness and porosity of the surface material are increased,
A reduction in the surface area available for adhesion is unavoidable, and adhesion inevitably deteriorates.

For the above reasons, none of the conventional surface materials has excellent absorption performance and adhesion, and this has been a major obstacle to improving the performance of absorbent articles.

[Means to solve the problem]

Therefore, the present inventors conducted extensive research in order to maintain the high level of absorption performance of the surface material and provide excellent adhesive properties, and as a result, they completed the present invention.

That is, the present invention relates to a surface material for an absorbent article, wherein the thickness of both sides is 273 or less than the thickness of the center, and the basis weight of the center and both sides are substantially the same. It is.

As a result of considering the problems of conventional surface materials as mentioned above, the present inventors were able to find a clue to the solution by considering the following. That is, (1) Absorption performance required of the surface material is necessary for the part that should absorb liquid (use surface), and is not particularly required for both sides of the absorbent article and the clothing side (non-use surface).

■ Adhesive properties of the surface material are particularly required near the sides of the absorbent article, which are susceptible to irregular stresses from the crotch, and at the cut surfaces of both sides of the surface material (i.e., on both sides), where the bonded area is likely to break. (edges), the used side of the absorbent article is not required to have adhesive properties on the unused side.

From the above, in the surface material according to the present invention, the central part of the surface material is finished as bulky as possible, and the thickness of both sides including the cut surface of the surface material is reduced to improve adhesion.
We succeeded in achieving both absorption performance and adhesiveness.

In addition, by densifying both sides and reducing bulk or porosity, liquid diffusion is suppressed and leakage of liquid from the sides is reduced, and both sides of the surface material can be easily cut.
The ease of assembly into absorbent articles has been greatly improved, and
In particular, it has become clear that when a nonwoven fabric is used as the surface material, it provides a number of very desirable advantages that were not expected at the beginning, such as preventing fibers from falling off from the cut surface.

[For production]

The surface material according to the present invention will be explained in more detail below.

In order to provide the necessary adhesion to the surface material, it is necessary that at least both sides including the cut portion of the surface material be thin, and it is preferable that at least the portions from both side edges of the surface material to the inside of the surface material be thinner than the central portion. More preferably, all portions of the absorbent article other than the portion that corresponds to the use surface are thinner than the portions that correspond to the use surface. The area where the surface material is used differs in size depending on the absorbent article, but for example, for sanitary napkins, it is at least a 4Qmm wide part at the center of the nonwoven fabric, and for disposable diapers, it is at least 80mm wide. handle. If the thickness of both sides of the surface material is 273 mm or less than that of the center part of the surface material, the necessary adhesiveness can be provided;
If it is 2 or less, even more sufficient adhesiveness will be provided. The specific value of the thickness of both sides of the surface material varies depending on the use of the absorbent article, but for example, in the case of sanitary napkins, the thickness of the surface material on the use side is 0.2 to 2. Qmm is preferable, and since 0.5 to 4.0 mm or more is desired for use in disposable diapers, the specific value of the thickness of both sides of the surface material is determined from each of these thicknesses.

Any method can be used to reduce the side thickness. For example, methods include adding a three-dimensional shape to only the central part of the surface material by heat forming, etc., applying pressure and compression to the surface material using rollers, or a combination of these methods, depending on the material used. It is sufficient to use the method described above. The easiest method to implement is to reduce the thickness by pressure compression treatment.

There are no particular restrictions on the material constituting the surface material, and known materials may be used. Examples include fiber aggregates such as paper, nonwoven fabrics, nets or films made of synthetic resin, and composites thereof. However, when emphasis is placed on texture, nonwoven fabrics are preferable. It is also possible to improve the texture.

There are no particular restrictions on the resin that forms the net or film, but in consideration of liquid return prevention properties, polyolefins, copolymer resins of olefins and other vinyl monomers (vinyl acetate, ethyl acrylate, etc.), polyesters, nylon, acetate, etc. Hydrophobic resins such as and blend polymers thereof are preferable, and in consideration of texture, polyolefins, copolymer resins of olefins and other monomers, or blend polymers thereof are preferable.

On the other hand, nonwoven fabrics with various compositions or manufacturing methods can be used, but in consideration of liquid return prevention properties and texture, dry heat bonding type nonwoven fabrics are particularly preferred, and in this case, the selection of binder fibers and non-binder fibers Although not particularly limited, examples of binder fibers include PE-PP composite fibers, PE-PET composite fibers, PP-PET composite fibers, low melting point PET-PET composite fibers, etc., and non-binder fibers include PP, PET, etc. , acrylic, nylon, etc. are often used. Considering thermal adhesion, P as the binder fiber
Composite fibers such as E-PET composite fibers and low melting point PET-PET composite fibers having a large difference in heat melting temperature between the two components are preferred. Further, the PE resin component in the composite fiber may have any of high density, low density, and chain low density, but high density is preferable in consideration of strength.

The basis weight of the surface material is not particularly limited, but there is a desirable range depending on the application, for example, 10 to 40 g/m' for sanitary napkins, and 20 to 6 g/m' for disposable diapers.
0 g/m' is common.

In order to further improve the absorbent performance of the absorbent article, appropriate areas of the surface material can be subjected to hydrophilic treatment or water repellent treatment. For example, it is possible to treat the entire surface of the surface material to make it hydrophilic to improve liquid permeability, or to make the entire surface material water repellent to improve the ability to prevent liquid return. By making the side portion hydrophilic or making the side portion water repellent, or by combining these in some cases, by setting the hydrophilicity of the side portion to be lower than that of the center portion, the above-mentioned effect of densification of the side portion can be improved. Combined with this, liquid diffusion on the sides is highly suppressed,
It is also possible to dramatically reduce leakage from the sides.

Methods of making the surface hydrophilic or water repellent include, for example, applying a surfactant to the surface material, or chemically bonding a monomer with a hydrophilic (hydrophobic) group or a polymer with a hydrophilic (hydrophobic) group to the surface. The surface may be modified by physical surface modification such as modification, plasma treatment, or incorporation of a chemical substance having a parent wood (hydrophobic) group. In addition,
In chemical surface modification, chemical substances with hydrophilic (hydrophobic) groups may be chemically bonded to the surface material, or chemical substances with parent wood groups may bond with each other to form cross-links and cover the surface material. .

Incidentally, the surface material of the present invention is not limited to the detailed examples, but can be variously modified within the range specified above.

[Examples and comparative examples]

The present invention will be described below with specific examples, but the present invention is not limited to these examples.

Surface materials according to the present invention and comparative surface materials having various configurations were manufactured, and their performance was evaluated using the methods shown below. The results are shown in Tables 3 and 2 for sanitary napkins and disposable diapers, respectively.

(1) Manufacturing method of surface material Embossed film (1): Manufactured by providing apertures 2 in the shape shown in FIG. 1 on a polyethylene film 1 using an embossing roller.

Embossed film (2): Manufactured by providing apertures 2 in the shape shown in FIG. 2 on a polyethylene film 1 using an embossing roller.

Net: Manufactured by slitting a polyethylene film 1 and then stretching it to provide openings 2 in the shape shown in FIG.

Nonwoven fabric: A fibrous web having the composition shown in Table 1 was prepared using a miniature card, and then treated with hot air.

Table 1 However, SH: Polyethylene/polyester composite fiber (manufactured by Daiwabo ■) ES: Polyethylene/polypropylene composite fiber (manufactured by Chisso ■) PET: Polyester fiber (manufactured by Kijin ■) NBF: Polyethylene/polypropylene composite fiber (manufactured by Daiwabo ■) (manufactured by Chisso) SHB: Polyethylene/polypropylene three-dimensional crimped composite fiber (manufactured by Chisso ■) The dimensions of the surface material are those of Examples 1 to 12 and Comparative Examples 1 to 8.
(For sanitary napkins) All length 200mm x
Width 170mm, Examples 13-24 and Comparative Examples 9-16
(In the case of disposable diapers), all had dimensions of 460 mm in length x 310 mm in width, and in the example, a predetermined width including the longitudinal cut surface was subjected to heat-pressure treatment to form both side parts having a thickness smaller than the central part. On the other hand, Comparative Example 1.3.5.7.9.1
No heat pressure treatment was performed in Comparative Example 2.1.13.15.
In 4.6.8.10.12.14.16, the entire surface material was subjected to heat and pressure treatment.

In addition, in Example 11, silicone-based water was applied to both sides of the 60 mm width including the vertical cut surface, and in addition to that, in Example 1.2, the front and rear ends of the 43 mm width including the horizontal cut surface were also injected with silicone water. Partial hydration treatment was performed by applying a chemical agent. Similarly, in Example 23, 55 m including the longitudinal cut surface
In Example 12, partial water repellent treatment was performed by applying a silicone-based water repellent to both sides of the 50 mm width including the transverse cut surface. .

(2) Thickness measurement method Tensilon RTM-25 model (Toyo Baldwin @!) was used. First, as shown in Figure 4, the end of the compression load cell 3 (hereinafter referred to as cell) was Diameter 3
A 0 mm pressure receiving plate 4 is attached, and then, as shown in FIG. 5, it is brought into gentle contact with the sample stage 5 and a load of 5 kg is applied.

At this time, the distance between the pressure receiving plate 4 and the sample stage 5 is set to 0.

Next, the cell was raised 101'l1m, and the surface material was placed on the sample stage 5 with the side that should be in contact with the skin facing up, as shown in Figure 6.The cell was lowered and the load applied to the surface material was transferred to the recording paper. Record. The measurement conditions are as follows.

Cell descending speed: 5 mm/min Recording paper full scale: log Recording paper scanning speed + 100 mm/min The compressive load recorded on the recording paper is as shown in FIG. For this recording paper, measure the distance d from the point when the cell starts descending to the point B when the cell contacts the surface material and starts applying load, and calculate the thickness t of the surface material using the following equation (1). (mm).

t = (200-d)/20・(1)(
3) Performance evaluation method When evaluating each of the following performances except for items ii), 1ii) and iv) below, the absorber and leakage preventive material in Table 2 and the specified surface material should be assembled into the specified configuration. Accordingly, a sanitary napkin sample or a disposable diaper sample was prepared and tested.

i) Absorption time and return amount: The time required for the napkin sample or the disposable diaper sample to absorb a predetermined amount of the test liquid was defined as the absorption time.

Generally, the smaller the absorption time, the better the liquid permeability. Further, a predetermined pressure was applied, and the amount of test liquid that returned from the inside was measured, and was defined as the amount of return. The smaller the amount of return, the better the ability to prevent liquid return.

11) Adhesive strength (1): The surface material 6 and polyethylene laminate paper (leakproof material) 7 are thermally bonded to the filaments using a sealer, and a sample of a predetermined width including the sealed portion 9 as shown in FIG. 10 is cut out. As shown in FIG. 11, the end of the surface material 6 and the end of the laminate paper 7 were each fixed with a chuck 10, and the maximum load generated when pulling was defined as the adhesive strength.

111) Adhesive strength (2): The surface material and the polyethylene film were bonded to the filaments using a hot-melt adhesive. The subsequent operations are the same as in li).

iv) Dynamic absorption amount: A hypothetical sanitary napkin sample 12 is attached to a movable female waist model 11 as shown in FIG. 12, and the test liquid is injected from the tube 13 while walking, and when leakage is observed. The amount of test liquid injected at was defined as the dynamic absorption amount.

It can be said that the larger the dynamic absorption amount, the more difficult it is to leak.

■) Maximum Absorption Amount 2 Lay the infant model 14 as shown in Figure 13 on its side, attach the disposable diaper sample 15, inject the test liquid from the tube 16, and inject the test liquid when leakage is detected. The amount was taken as the maximum absorption amount. The greater this maximum absorption amount, the more
It can be said that it is difficult to leak.

iv) Cuttability: The state of the surface material after attempting to cut it with a rotary cutter was ranked into the following three categories.

Grade 3: No flakes or protruding fibers were observed in the cut portion, and the cutting performance was good.

Grade 2: Protrusion of cracks and fibers are observed in the cut portion, but it can be cut.

Grade 1: Impossible to cut.

vj) Texture The feel of the surface material when lightly stroked with the palm of the hand was ranked into the following three categories.

Grade 3: No slimy or stiff feeling.

Grade 2: Slight sliminess and stiffness are felt.

Grade 1: Significant sliminess and stiffness are felt [Effects of the invention] As can be seen from the test results shown in Tables 3 and 4,
The surface material of the present invention not only has sufficient absorption performance and excellent adhesive properties, but also has excellent cutting properties. Among them, Examples 7 to 12 and 19 to 24, which used nonwoven fabrics, had stable and good texture, and especially Examples 1 to 8, and 11 to 24, in which the side portions extended to the end of the use surface, Examples 11 and 12. The leak-proof properties are also improved due to the liquid diffusion control that accompanies the densification of the side parts, and in addition, partial water drainage treatment is performed.
In Example 12.24, the leak-proofing properties have been dramatically improved, and among them, Example 12.24, in which the surface material was subjected to hydration treatment.
The effect is particularly remarkable, and it can be said that it is truly an ideal surface material.

On the other hand, comparative example 1.3.5.7.9.11.13
．． In No. 15, the entire surface material is thick, so although the absorption performance and texture are good, the adhesion and cuttability are poor. Furthermore, in Comparative Examples 2.4.6.8.10.12.14.16, the entire surface material was thin, so although the adhesion and cuttability were good, the absorbency and texture were poor. Therefore, it must be said that the materials shown as comparative examples are extremely inadequate as surface materials for absorbent articles.

[Brief explanation of the drawing]

Figures 1 to 3 are enlarged views of the openings in the embodiments of the surface material according to the present invention, Figures 4 to 7 are diagrams showing the method for measuring the thickness of the surface material, and Figure 8 (a) is the physiological (b) to (f) are sectional views taken along the line X-X of FIG. 8(a) showing various internal configurations, and FIG. 9(a)
) is a perspective view showing the configuration of a hypothetical disposable diaper sample.
(b) to (f) are x-X sectional views of FIG. 9(a) showing various internal structures, FIGS. 10 to 11 are diagrams showing the method of measuring adhesive strength, and FIGS. 12 to 13 are respectively It is a figure which shows the measuring method of dynamic absorption amount or maximum absorption amount. 1... Film 2... Opening 3... Cell 4... Pressure receiving plate 5... Sample stage 6... Surface material 7... Leak proof material 8... Absorber 9...・Adhesive part 10...Chuck 11...Female waist model 12...Sanitary napkin sample 13...Tube 14...Infant model 15...Disposable diaper sample Figure 3

Claims (1)

[Claims] 1. The thickness of both side parts is 2/3 or less of the thickness of the central part,
A surface material for an absorbent article, characterized in that the basis weight of the central part and both sides are substantially the same. 2. The surface material for an absorbent article according to claim 1, wherein the thickness of both side portions is reduced by compression treatment.