JPH02168950A - Surface material for absorptive article - Google Patents

Abstract

PURPOSE:To greatly improve dryness after use by allowing an oil component having <=10000mol.wt. and <=50dyn/cm surface tension at 25 deg.C to exist on the surface of the side of a hydrophobic liquid permeable film where the sheet comes into contact with the skin. CONSTITUTION:Any materials, such as polyolefin, which have a hydrophobic property, are usable as the resin to form a film layer. For example, holes 3 are formed to an olefin heat-bonded non-woven fabric 2 laminated with a polyethylene film 1. The surface material consists of such hydrophobic liquid permeable film and the requirement for this sheet is that the oil component having <=10000mol.wt. and <=50dyn/cm surface tension at 25 deg.C exists on the surface thereof. The oil component may be in any of a liquid, semi-solid or solid state and the component which is liquid to semi-solid at the bodily temp., i.e., 36.5 deg.C is more preferable when the effective workability on the entire surface with a small amt. is taken into consideration. The mol.wt. is required to be <=10000, more preferably <=1000.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention generally relates to absorbent articles such as sanitary products that adhere closely to the body and absorb and retain excrement including liquid from the body. This relates to surface materials. More specifically, the present invention relates to a surface material suitable for use in sanitary napkins and similar products.

[Prior art and problems to be solved by the invention] Sanitary products used for absorbing and retaining body fluid-containing excreta are composed of an absorbent body that has the function of absorbing and retaining excreta, and a liquid-impermeable material. It is well known that the skin is composed of a leak-proof material and a surface material that is permeable to excrement and that comes into direct contact with the body.

To increase the effectiveness of sanitary products, the absorbent capacity and/or
Efforts are continuing to improve retention, and significant progress has been made. While fluff pulp alone was used as the absorbent material, today it is common practice to further add a superabsorbent polymer to fluff pulp to improve absorbency. However, this absorbent body cannot exhibit its effectiveness unless excrement is effectively transferred to the absorbent body, and therefore the performance of the sanitary product as a whole deteriorates.

Therefore, as a function of the surface material, it goes without saying that excrement is quickly transferred to the absorbent body (hereinafter referred to as Wl, permeability), and furthermore, the liquid transferred to the absorbent body is not only able to absorb pressure but also An important function is to prevent the liquid from returning to the body even if it overflows from the absorbent body (hereinafter referred to as liquid backflow prevention). Particularly in sanitary napkins where the liquid excreted is menstrual blood containing highly viscous liquid, liquid permeability is an important function.

Furthermore, in sanitary products, in addition to the hard function of absorbing and retaining fluid, which gives a sense of confidence, the psychological soft function of comfort is also a major factor. Psychological comfort is largely dependent on the surface material that comes into direct contact with the body; soft,
In addition to the gentle texture, the dryness after use of the surface material, that is, the small amount of menstrual blood remaining on the surface, and the perception of cleanliness after use due to the fact that the color of menstrual blood transferred to the absorbent material is not visible. factors are important factors.

Only by having these hard and soft functions can sanitary products be desired by women. To achieve this objective, various proposals have been made, and there are many improved techniques.

Specifically, first, a nonwoven fabric, which is an aggregate of hydrophobic fine fibers, is used as the surface material to form a space with a hydrophobic atmosphere between the body surface and the absorbent body, thereby allowing liquid to return without impairing liquid permeability. Technology to improve prevention (Japanese Patent Application Laid-Open No. 58-1806
02 Publication). However, in nonwoven fabrics, the liquid that should be transferred to the absorbent material tends to be retained in the microscopic spaces that are inevitably formed as an aggregate of fibers, and when pressure is applied, the retained liquid easily transfers to the body surface, which is a fatal problem. Therefore, no matter how hydrophobic fibers are used, there is a limit to the improvement in liquid return prevention properties. Furthermore, since it is an aggregate of fine fibers, although it has a soft texture, it does not necessarily improve dryness after use due to the ability to retain liquid in the micro spaces.

On the other hand, a technology to improve liquid return prevention by using a hydrophobic sheet with holes as a surface material (in 1983)
4-124398, JP-A-57-1340, JP-A-61
-45753) have also been proposed.

Indeed, if a perforated hydrophobic sheet is used as the surface material, retention of liquid in the surface material will not occur.

However, because it is a hydrophobic film, it is necessary to create holes in the film and increase the area of the holes for the free passage of liquid, and it is not always possible to prevent the liquid from returning to the body due to the application of pressure. The ability to block menstrual blood after use, that is, the dryness, is also not desirable.

Furthermore, with hydrophobic perforated sheets, the surface area that comes into contact with the body is large, so it does not necessarily feel good when it comes in contact with the body, and even after use, menstrual blood tends to remain on the surface, making it difficult to feel dry after use. It's not always satisfying. To solve this problem, an improved technology of embossing is used to create unevenness on the film surface (Japanese Patent Laid-Open No. 56-9401
Although an improved technique (Japanese Patent Publication No. 17081/1981) has been proposed in which the shape of the opening is made into a tapered capillary structure, it is still insufficient.

There is a contradictory relationship between liquid permeability and dryness after use, that is, the ability to prevent liquid stagnation.If you also take into account the gentle texture, there is currently no surface material that satisfies the needs of the user. It is hoped that a surface material with a certain surface will emerge.

[Means to solve the problem]

The present inventors have solved this problem by making an oil component, which has a lower surface tension than menstrual blood, on the surface of a liquid-permeable sheet made of a hydrophobic material. It was discovered that it is possible to obtain a surface material suitable for use in sanitary products, especially sanitary products, which has excellent feel, dryness after use, liquid permeability, liquid stagnation prevention properties, and good texture, and has now completed the present invention. Ta.

That is, the present invention is a liquid-permeable sheet made of a substantially hydrophobic material, and at least the surface that comes into contact with the skin has a molecular weight of 10,000 or less and a surface tension at a temperature of 25°C. 50
The present invention provides a surface material for an absorbent article characterized by the presence of an oil component having a content of dyn/co+ or less.

In the surface material of the present invention, an oil component with a molecular weight of 10,000 or less and a surface tension of 50 dyn/c11 or less at a temperature of 25°C is present on the surface of the hydrophobic liquid-permeable sheet that comes into contact with the skin. It is an essential requirement to do so.

Examples of hydrophobic liquid-permeable sheets used in the surface material of the present invention include opaque liquid-impermeable hydrophobic films with openings through which liquid can pass, net-like sheets, and opaque liquid-impermeable hydrophobic films. Examples include a fiber aggregate laminated with a hydrophobic film with holes, or a nonwoven fabric made of hydrophobic fibers. Preferred examples include a hydrophobic film, net, and a nonwoven fabric made of hydrophobic fibers that have discontinuous holes in a planar state. The composite is an opaque sheet with discontinuous liquid-permeable spaces.

For films or nets that are simply liquid-impermeable hydrophobic films with specific openings, because the film is hydrophobic, it is necessary to increase the area of the openings for the free passage of liquid. Although the effect of preventing the liquid overflowing from the absorbent body from returning in the opposite direction, that is, toward the body, is weak, if there is an oil component on the surface that has a lower surface tension than menstrual blood, the surface may The amount of remaining liquid is reduced, the dryness after use can be significantly improved, and comfort can be provided to the user.

In the present invention, the shape of the openings in the hydrophobic film is preferably Japanese Patent Publication No. 57-17081,
No. 32581 each publication proposes a hydrophobic apertured film in which the aperture has a tapered capillary structure, and more preferably an opaque hydrophobic film having a top, a bottom, and a wall connecting them. This is a film in which at least a portion of the wall portion is provided with apertures, and the bottom portion has no apertures. After use, the opening area itself as seen from the surface is small, so it has excellent shielding properties and also has excellent liquid stagnation prevention properties, so it can be used preferably.

In the present invention, the most preferably used hydrophobic liquid-permeable sheet has a hydrophobic film layer on the side that comes into contact with the skin, and a hydrophilic film layer on the side facing the absorbent body in order to absorb menstrual blood. A liquid permeable sheet made of 2M fiber aggregates and integrated with 2N, the film layer being made of an opaque hydrophobic resin having a top, a bottom and a wall connecting them, and at least It is a liquid-permeable sheet with apertures provided in a portion of the wall and no apertures at the bottom.

In the present invention, the openings in the film layer can be freely formed within the range of the desired balance depending on liquid permeability, liquid backflow prevention properties, shielding properties for menstrual blood after use, and liquid residue on the surface, i.e., the surface tension of the oil component. However, for boat fishing, it is preferable that the size of the apertures is 0.1 to 2, and the density of the apertures is 10 to 100 pieces/cd.

In the present invention, the film layer is preferably opaque in order to impart sufficient Q-shielding properties to the surface material. If the film layer is opaque, the surface material of the present invention will also be opaque and can be preferably used as a surface material for absorbent articles that absorb colored liquids such as menstrual blood. The opacity of this surface material is quantified as whiteness, and the whiteness is preferably 10% or more. There are various methods for imparting opacity. For example, adding white pigment to the resin during the film manufacturing process, or coating the film surface with a mixture of white pigment and an appropriate binder. However, any method other than these methods may be used as long as the desired opacity can be imparted.

Any hydrophobic resin may be used to form the film layer. For example, polyolefins, olefins and other monomers (vinyl acetate, ethyl acrylate, etc.)
Synthetic resins such as polyester, nylon, and acetate, and blend polymers of these are included, but in consideration of texture and processability in actual production, polyolefins, copolymer resins of olefin with other monomers, or blends of these are included. Polymers are preferred, and among these, low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymers, or blends thereof are more preferred.

The surface material of the present invention is such a hydrophobic liquid-permeable sheet, and the surface material contains an oil component having a molecular weight of 10,000 or less and a surface tension of 50 dyn/cm or less at 25°C. Make it a requirement. This surface tension is 50dyn 7cm
Due to the presence of the following oil components, menstrual blood existing on the sheet surface can easily move to the openings at a small angle with respect to the sheet surface and the horizontal plane, and menstrual blood itself is not likely to remain on the sheet surface. , which allows the user to spend time comfortably.

The oil component used in the present invention may be in liquid, semi-solid, or solid form, but considering that it can effectively affect the entire surface with a small amount, it should be kept at body temperature, that is, 36.5°C.
It is preferably in a liquid to semi-solid state. The molecular weight needs to be 10,000 or less, preferably 7,000
It is not more than 1000, more preferably not more than 1000.

Specific examples of oil components include highly water-repellent silicone oils such as dimethylpolysiloxane and methylphenylpolysiloxane, fluorine compounds such as trifluorohexyl propionate, and higher alcohols such as oleyl alcohol, cetyl alcohol, and lauryl alcohol. , higher fatty acids such as capric acid and caproic acid, higher fatty acid esters such as 2-ethylhexanoic acid triglyceride, cetyl 2-ethylhexanoate, octyl laurate, and trimethylolpropane tristearate, and hydrocarbons such as liquid paraffin and octene. Examples include natural ester oils such as olive oil and castor oil, and natural waxes such as lanolin.

Particularly preferred oil components are water-repellent silicone oils and higher fatty acid esters such as 2-ethylhexanoic acid triglyceride due to their odor and stability over time.

Regarding the amount of oil components present on the surface of the hydrophobic liquid-permeable sheet, if there is a large amount, it will adhere to the user's body and give an unfavorable feel, but at least it will have the effect of improving dryness after use and texture on the body. It can't happen. The amount present on the sheet surface varies depending on the type of oil, but ranges from 0.1 g/rrr to 10. Og/n (preferably, more preferably 0.3 g/rrj to 3.0 g/+
It is vf.

In the present invention, in order to further improve the feel on the body, it is also preferable to emboss the hydrophobic liquid-permeable sheet and then add an oil component to the sheet.

In the present invention, the method for making the oil component exist on the surface is to apply the oil component to the side of the hydrophobic liquid-permeable sheet surface that comes into contact with the user's body using a known technique such as a gravure coater or spray. Alternatively, when making a hydrophobic liquid-permeable sheet in advance, it is kneaded into the resin, allowed to bleed out, and brought out onto the sheet surface.However, considering the stability of the hydrophobicity of the surface and productivity, the latter method is recommended. preferable.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 9, Comparative Examples 1 to 3 By applying the oil components shown in Table 1 to the specified base materials shown below in the specified amounts shown in Table 1 using the specified methods shown below, Various surface materials were made. Then, the surface material of the commercially available napkin “Laurier” (manufactured by Kao) was removed.
Instead, each surface material was constructed and used as a hypothetical napkin sample.

The obtained hypothetical napkin sample was evaluated by the following method. The results are shown in Table 1.

<Substrate> Laminated film-1: As shown in FIG. 1, a film produced by forming apertures 3 in a laminate of a low-density polyethylene film 1 on an olefin heat-bonded nonwoven fabric 2.

Laminated film-2 = After embossing a fine pattern on a low-density polyethylene film laminated to an olefin-based heat-bonded nonwoven fabric and providing microprotrusions with a height and interval of about 10μ, the same as laminate film-1 was prepared. A film manufactured by forming apertures in.

Net: Manufactured by slitting and stretching a low-density polyethylene film.

Non-woven fabric: Fabric manufactured by subjecting a web made of polyethylene/polyester composite fibers to hot air treatment.

<Adhesion method> A: A predetermined oil component was applied to the film side surface of the laminate film, or the surface of the net or nonwoven fabric using a gravure coater.

B: A predetermined oil component was added to the film raw resin during production of the laminate film.

<Evaluation method> (1) Amount of return 10 g of the red test liquid was injected into a hypothetical napkin sample, pressurized after a certain period of time, and the amount of the test liquid that returned through the surface material was defined as the return amount.

(2) Cleanliness After measuring the return amount, the surface condition of the hypothetical napkin sample was ranked into the following five categories.

Grade 5: No red color is observed in the test liquid.

Grade 4: Only a slight red color is observed in the test liquid.

Grade 3: The red color of the test liquid is slightly compressed.

Grade 2: The red color of the test solution is partially noticeable.

Grade 1: The red color of the test liquid is noticeable throughout.

〔Effect of the invention〕

As can be seen from Examples 1 to 11, the surface material according to the present invention has excellent liquid return prevention properties and cleanliness.

There are three base materials: laminate film, net, and nonwoven fabric.
Although various types have been tested, as can be seen from the evaluation results, the effect of the present invention is most remarkable in the case of laminate film, net is slightly inferior to this, and nonwoven fabric is considerably inferior.

In addition, the effect of Example 7 using laminate film-2 having microprotrusions was extremely remarkable, indicating that the above performance was dramatically improved due to the synergistic effect of the surface morphology of the base material and the attachment of the oil component. ing.

On the other hand, in Comparative Examples 1 to 3, since the base material to which no oil component is attached is used as a surface material, the liquid return prevention property and cleanliness are poor, and both are extremely insufficient as a surface material. I have to say that there is.

[Brief explanation of the drawing]

Figure 1 shows a laminate film used in an example of the present invention.
1 is a perspective view of FIG. 1: (t1 degree polyethylene film 2 Niolefin heat bond nonwoven fabric 3: Opening part

Claims (1)

[Claims] 1. It is a liquid-permeable sheet made of a substantially hydrophobic material, and at least the surface that comes into contact with the skin is coated with an oil having a molecular weight of 10,000 or less and a surface tension of 50 dyn/cm or less at a temperature of 25°C. A surface material for an absorbent article characterized by the presence of a component.