JPS6128003A - Absorber in sanitary article and its production - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an absorbent material for sanitary articles including disposable diapers, sanitary napkins, incontinence pads, etc., and in particular, the present invention relates to absorbent materials for sanitary articles such as disposable diapers, sanitary napkins, and incontinence pads. The present invention relates to an absorbent body having a core layer arranged as a support for a water-absorbing polymer.

(Prior art) Pulverized pulp is economical and flexible, and superabsorbent polymers have high water absorption and retention properties and do not release absorbed water even under pressure. It is used as an absorbent material in sanitary products such as sanitary napkins.

However, the pulverized pulp has poor retention properties in the state in which it forms a layer as an absorbent material, and furthermore,
Since its fiber binding strength is weak and its capillary action is small, it is inferior in body fluid diffusivity compared to crepe absorbent paper (paper cotton) used as a constituent material of absorbent bodies such as napkins. In addition, hypertonic Y'RC polymers also have poor body fluid diffusivity and permeability, making it impossible to use them effectively.Moreover, they are in powder or fibrous form, and when they absorb body fluids and swell. , are in continuous contact with each other to form a body fluid permeation barrier.

Therefore, the following techniques are known.

(1) In order to eliminate the above-mentioned drawbacks of pulverized pulp, it is possible to compress and densify the pulp layer in the presence or absence of water, as disclosed in U.S. Pat.
It is disclosed in publications such as No. 7304 and Japanese Patent Publication No. 54-36793.

(2) In order to eliminate the above-mentioned drawbacks of highly water-absorbing polymers, it is possible to bond the polymers to water-absorbing paper, non-woven fabrics, etc. that have body fluid diffusing properties, as disclosed in Japanese Patent Application Laid-open Nos. 54-4498 and 54-141.
No. 857, No. 54'-158096, No. 56-605
This is disclosed in publications such as No. 55.

(3) In order to eliminate the above-mentioned drawbacks of superabsorbent polymers, pulverized pulp is placed on both sides of the center layer in which a fiber web contains a mixture of pulverized pulp and superabsorbent polymers, and this laminate is used as needed. It was actually published in 1986-6096 that compressed
No. 56-6097, No. 56-6098, etc.

(4) In order to reduce the bulk of the absorbent body and impart high absorption retention, it is possible to mix and compress pulverized pulp and a powdered super absorbent polymer, as disclosed in U.S. Pat. No. 3,661,154 and JP-A-5
It is disclosed in No. 2-20692, No. 55-3632, etc.

(5) In order to bond a powdered super absorbent polymer to a sheet that has body fluid diffusing properties, the polymer is made sticky in the presence of moisture, and this stickiness is used to fix the polymer to the sheet. This is disclosed in the above-mentioned Japanese Patent Application Laid-open Nos. 54-1498 and 54-141857.

(6) When powdered superabsorbent polymers absorb body fluids and swell, it is necessary to regulate the amount of the polymers used so that they do not come into continuous contact with each other and form a body fluid permeation barrier. This is disclosed in publications such as JP-A No. 54-4498.

(Problems to be Solved by the Invention) In particular, the techniques disclosed in (2) and (3) above have the following problems in making effective use of superabsorbent polymers:
It is superior to other conventional techniques and deserves evaluation. However, in the absorbers according to these technologies, as a body fluid diffusive sheet that binds and supports superabsorbent polymers,
If absorbent paper is used, the strength of the absorbent paper under wet conditions is extremely low, so it is easily deformed and damaged by the movements of the wearer's crotch, and cannot perform its function. If such deficiency A is used,
However, since body fluids generally do not have directional diffusion,
Body fluids spread horizontally and vertically. The tendency to curl is undesirable in sanitary articles such as disposable diapers, sanitary napkins, and incontinence pads. In this type of article, it is preferable to increase the dispersibility of bodily fluids in the vertical direction and reduce it in the lateral direction, thereby making effective use of the absorbent material and preventing leakage from the lateral direction. It is. Even with nonwoven fabrics, the diffusion properties in the longitudinal direction may be improved to some extent by using parallel webs in the longitudinal direction as constituent fibers, but this is inferior to crepe absorbent paper. , so also.

When used as a support material for superabsorbent polymers, it is still unsatisfactory in terms of its effective use.

(Means for Solving the Problems) In the present invention, this type of article has a body fluid diffusion direction that is comparable to that of crepe absorbent paper, which is known and used as a sheet with excellent body fluid diffusion properties. It is an object of the present invention to effectively solve the above-mentioned problems by disposing a special nonwoven fabric having the following properties as part of the core layer of an absorbent body.

The gist of the present invention to achieve the above object is that a powdery or fibrous superabsorbent polymer is substantially evenly distributed and bonded to a nonwoven fabric made of lignophilic fibers of 70 or more layers. The nonwoven fabric is made up of a core layer that is woven into a core layer, and a pulverized pulp layer that is laminated on at least one side of the core layer, and this laminate is compressed and integrated in the thickness direction, and the nonwoven fabric maintains its shape by intertwining the fibers with each other. The present invention also provides an absorbent body for use in sanitary articles, characterized in that it has a vertical striped pattern in which portions with high fiber density and portions with low fiber density are arranged alternately in the width direction of the article, and a method for manufacturing the same.

Further, the present invention will be described below based on illustrated examples.

FIGS. 1 and 2 are schematic cross-sectional views in the thickness direction of the absorbent body of the present invention in an uncompressed state. The absorbent body 1 consists of a core layer 2 and a pulverized pulp layer 3 integrally laminated on one side of the core layer 2 (Fig. 1), or a core layer 2 and a pulverized pulp layer 3 integrally laminated on both sides thereof (Fig. 1). pulverized pulp layer 3 (second
figure). In the illustrated example, the core layer 2 and the pulverized pulp layer 3 are separated, but it should be understood that they are actually in contact with each other. The core layer 2 is composed of a nonwoven fabric 4 and a powdered or fibrous superabsorbent polymer 5 bonded to the nonwoven fabric 4 in a substantially evenly distributed manner.

The superabsorbent polymer 5 exists on the upper surface of the nonwoven fabric 4 as shown in FIGS. 1 and 2, and also exists inside the nonwoven fabric 4 as shown in the schematic enlarged cross-sectional view of FIG. 3. , although not shown, may exist on the lower surface of the nonwoven fabric 4.

FIG. 4 shows a schematic enlarged plan view of the nonwoven fabric 4. FIG. The nonwoven fabric 4 has a vertical striped pattern in which portions 4a with high fiber density and portions 4b with low fiber density are arranged alternately in the width direction, and the sheet form is maintained by intertwining the fibers in a three-dimensional direction, and the vertical striped pattern is absorbed. It is oriented in the longitudinal direction of the body 1. Such nonwoven fabric 4 is disclosed in Japanese Patent Application Laid-Open No. 55-71115 filed by the present applicant.
No. 3, No. 57-39268, and U.S. Patent No. 34498
No. 09, No. 3,485,706, etc., i.e., a method in which a fibrous web is guided onto a support and treated with a high-speed stream of water that crosses the web in its width direction and is ejected from orifices at predetermined intervals. It can be obtained by

The fibers constituting the nonwoven fabric 4 are wood-loving fibers, especially rayon fibers of 100% by weight in order to obtain excellent body fluid dispersibility.
However, it may contain 30% by weight or less of hydrophobic fibers such as polyester or polypropylene for reasons such as retention of elasticity under wet conditions and efficiency in forming a web with a card. The fibers used have a fineness of 1 to 8 d, preferably 3 to 6 d, and a fiber length of 10 m or more, preferably 40 to 100 m.

The basis weight of the nonwoven fabric 4 is preferably 15 to 60 g/d, although it depends on the amount of the superabsorbent polymer 5 distributed therein.

Examples of the super absorbent polymer 5 include starch,
Examples include cellulose type and synthetic polymer type. That is, saponified products of starch-acrylic acid (salt) graft copolymer, starch-ethyl acrylate graft copolymer,
Saponified starch-methyl methacrylate graft copolymer, saponified starch-acrylonitrile graft copolymer, saponified starch-acrylamide graft copolymer, starch-acrylonitrile-2-acrylamide-2-methylpropanesulfonic acid graft Saponified product of copolymer, starch-acrylonitrile-vinylsulfoneacrylic acid (salt) polymer, saponified product of methyl methacrylate-vinyl acetate copolymer, polyethylene oxide cross-linked with acrylic acid, sodium-lium carboxymethyl cellulose crosslinked products of polyvinyl alcohol-maleic anhydride reactants, etc.

The superabsorbent polymer 5 has an absorption and retention capacity of 20 times or more of its own weight, and has the property of being water-insoluble and swelling and gelling when it absorbs a large amount of water.

The amount of superabsorbent polymer 5 distributed is 20 to 500%, preferably 60 to 300%, of the weight of the web in the dry state of the polymer and nonwoven fabric 4, and this amount of superabsorbent polymer 5 is substantially When the superabsorbent polymer 5 absorbs water and swells,
The particles have minimal mutual interference and are less likely to come into continuous contact to form a body fluid permeation barrier, allowing body fluid to pass through in three dimensions.

The pulp of the pulverized pulp layer 3 has conventionally been generally used as a constituent material of absorbers for sanitary products such as disposable diapers and sanitary napkins, and has a fiber length of 5 nwn obtained by mechanically defibrating the pulp sheets 1 to 1. These are as follows. The amount of pulp used varies depending on the absorbent material of the intended sanitary product, for example, whether the absorbent material is used alone, multiple layers are used, or whether other absorbent materials are used together with the absorbent material 1. However, each pulverized pulp layer 3 is generally made to have a weight of 50 to 00 g/rrr.The pulverized pulp layer 3 is compressed in the thickness direction so as to be integrated with the core layer 2 in a laminated state. When compressed in this way, the particle spacing of the superabsorbent polymer 5 becomes narrower than that when it is not compressed, but the superabsorbent polymer 5 is designed so that it is less likely to form the barrier when it absorbs water and swells. 5 is distributed. In such a compressed state, a portion of the core layer 2 and the pulverized pulp layer 3 are mixed with each other, and the boundary between the two is not clearly distinguished, and in the boundary area, The pulp of the pulverized pulp layer 3 is mixed in the fibers of the nonwoven fabric 4 and the superabsorbent polymer 5, and the pulverized pulp layer 3 adjacent to the core layer 2
The pulp is compacted to a high density to form a body fluid diffusion assisting layer.

The absorbent body 1 may be compressed in a continuous plane by using a roll with a smooth circumferential surface so that the density of the absorbent body 1 is substantially uniform over the entire circumference, but it is also possible to compress the absorbent body 1 in a continuous planar manner so that the density of the absorbent body 1 is substantially uniform over the entire circumferential surface. It is preferable that the density of the absorbent body 1 is partially different depending on the roll, etc., and that the embossing 6 has a pattern arrangement as illustrated in FIG. In the case of embossing, the compressed portions and non-compressed portions may be continuous or discontinuous, but it is preferable that the interval between the compressed portions be as narrow as possible.

The absorbent body 1 as described above can be manufactured by the following method.

A pulverized pulp layer 3 is formed, a nonwoven fabric 4 is laminated on the pulp layer, a superabsorbent polymer 5 is substantially evenly spread on the web, and the polymer absorbs moisture from above the web and becomes sticky. After spraying a certain amount of water in a spray state and further laminating a pulverized pulp layer 3 on the web as necessary, the laminate is compressed in the thickness direction and integrated to obtain the absorbent body 1. . The water sprinkling may be carried out at any appropriate step from the lamination of the nonwoven fabric 4 to after the superabsorbent polymer 5 is sprayed, for example.

This may be done either at the time of laminating the nonwoven fabric 4 or at the time of spraying the superabsorbent polymer 5.The key is to make the surface of the superabsorbent polymer 5 absorb the sprayed water and become sticky. The preferred amount of spraying is 15% or less of the weight of the superabsorbent polymer 5. In the laminated compressed absorbent body 1 thus obtained, the pulp inside the compressed pulverized pulp layer 3 and the fibers of the nonwoven fabric 4 adhere to each other due to the adhesiveness caused by the moisture absorption of the superabsorbent polymer 5, and the fibers of the nonwoven fabric 4 in this part adhere to each other. The mixture, especially the pulp, is solidified to a high density by hydrogen bonding caused by the sprayed water to form a body fluid diffusion assisting layer.

The pulverized pulp layer 3 is formed by defibrating and stacking the valve seat using a hammer mill or the like, and the nonwoven fabric 4 is formed by forming a web using a card and then using the above-described nonwoven fabric manufacturing method.

Further, the pulverized pulp layer 3 may be formed during the lamination process or may be formed in advance before the process, and it is preferable that the nonwoven fabric 4 be formed before the process. . The spray water may be an aqueous solution of polyvinyl alcohol or the like at an appropriate concentration. When the core layer 2 is formed in advance and the nonwoven fabric 4 is relatively bulky and the highly absorbent polymer 5 is distributed therein, a suction is placed on one side of the nonwoven fabric 4 and the highly absorbent polymer 5 is distributed from the other side. The polymer 5 may be sucked into the nonwoven fabric 4.

The absorbent body 1 having the above-mentioned structure and obtained by the manufacturing method is used singly or in a stack of multiple absorbers in sanitary articles such as disposable diapers and sanitary napkins, or as the case may be. Used in conjunction with other absorbent materials.

Note that the pulverized pulp layer 3 may be formed by spreading a water-absorbing carrier sheet on a conveyor in the manufacturing process and scattering and accumulating the pulverized pulp thereon. Even after formation, it is used as a part of the pulp layer without being separated. Therefore, the absorbent core 1 of the present invention may include such a sheet.

(Function) The absorbent body 1 is placed inside the sanitary article so that the pulverized pulp layer 3 is located on the wearer's skin side (the upper side in FIG. 1), but the body fluids absorbed into the pulverized pulp layer 3 are , quickly diffuses along the high-density portions 4a extending in a striped pattern in the longitudinal direction of the nonwoven fabric 4, and is absorbed and retained by the superabsorbent polymer 5. In this case, a certain amount of body fluid diffuses in the lateral direction of the nonwoven fabric 4, but since the high density portions 4a are intermittently located in the lateral direction, that is, the low density portions 4b Since it is located between the dense portions 4a, its diffusion rate is much slower than that in the vertical direction, and the number of diffusion agents is small. Therefore, the diffusion range of body fluids on the nonwoven fabric 4 becomes a substantially elliptical shape that is elongated in the vertical direction. Further, when the absorbent body 1 is provided with embossing 6 as illustrated in FIG. 5, the body fluid in the pulverized pulp layer 3 diffuses along the embossing 6. In addition, if the pulp of the pulp layer at the boundary between the core layer 2 and the pulverized pulp layer 3 is compacted to a high density to form a body fluid diffusion auxiliary layer, the auxiliary layer will also cause diffusion. The speed is much slower than that in nonwoven fabric 4. In the case where there is residual body fluid that is thus diffused and absorbed and retained by the superabsorbent polymer 5, and the crushed pulp layer 3 is also arranged on the side opposite to the wearer's skin side (lower side in FIG. 2). This also absorbs body fluids.

(Embodiment) FIG. 6A is a plan view showing an example of a disposable diaper, and FIG. 6B is a schematic sectional view of a part of the absorbent body taken along line XX in FIG. 6A. The diaper 11 includes a water-impermeable back sheet 12 such as a polyethylene film.

It consists of a water-permeable topsheet 13 such as a nonwoven fabric, and an absorbent body 1 interposed between them.

FIG. 7A is a plan view showing an example of a sanitary napkin, and FIG. 7B is a schematic sectional view taken along line XX@ in FIG. 7A. The napkin 21 consists of an absorbent body 1, a polyethylene film that covers the lower surface and both sides of the absorbent body, a water-impermeable back sheet 22 such as a laminate of this and paper or non-woven fabric, and a water-permeable top sheet 23 such as a non-woven fabric that covers the entire absorbent body 1. Consisting of

In the illustrated example, the absorbent body 1 is used alone, but as described above, it may be used in multiple layers or in combination with other absorbent materials, and may also be used by folding as appropriate. . Moreover, it goes without saying that the width of the distribution of the core layer 2 and the superabsorbent polymer 5 may be the same as that of the pulverized pulp layer 3, or may be narrower than that of the pulverized pulp layer 3.

(Effects of the Invention) According to the present invention, since it has the above-mentioned structure and function, compared to absorbers in known sanitary articles containing superabsorbent polymers, The effective utilization is greatly increased, and as a result, less material is required for the absorbent body 1, and due to this and the fact that the absorbent body 1 is compressed, the bulk of the absorbent body 1 can be significantly reduced. Of course, since the nonwoven fabric 4 of the core layer 2, which has excellent body fluid dispersibility in the longitudinal direction, is arranged, the amount of body fluid absorbed per unit surface of the absorbent body 1 is reduced. Bleeding and backflow are significantly reduced.Leakage from the lateral direction is prevented in both cases, and the compression and excellent shape retention of the nonwoven fabric 4 combine to keep the entire absorbent body 1 moist due to absorption of body fluids. This has the advantage that it does not lose its shape even when worn underneath.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic partial cross-sectional views of the absorbent core of the present invention, FIG. 3 is a partial cross-sectional view showing an example of a core layer that is a part of the absorbent core, and FIG. A schematic enlarged plan view of a part of the nonwoven fabric structure, FIGS. 5A and 5B. C is a partial plan view showing an example of embossing applied to the absorbent body, FIG. 6A is a plan view showing an example of a disposable diaper with a portion cut away, and FIG. 6B is a line taken along line X-X of FIG. 6A. FIG. 7A is a plan view showing an example of a sanitary napkin, and FIG. 7B is a schematic cross-sectional view taken along line X-X in FIG. 7A. 1... Absorbent body 2... Core layer 3... Crushed pulp layer 4... Nonwoven fabric 5... Super absorbent polymer 6. Emboss 11... Disposable diaper Figure 1 Figure 2 Figure 3 No. 4 Illustration 5

Claims (26)

[Claims] (1) A core layer in which a powdered or fibrous superabsorbent polymer is substantially evenly distributed and bonded to a nonwoven fabric made of 70% by weight or more of hydrophilic fibers, and laminated on at least one surface of the core layer. This laminate is integrated by compression in the thickness direction, and the nonwoven fabric maintains its shape by intertwining the fibers, and the high fiber density and low fiber density parts form an article. An absorbent body for a sanitary article characterized by having a vertical striped pattern arranged alternately in the width direction. (2) The absorbent body in the sanitary article according to claim 1, wherein the compression is an embossment arranged in an appropriate pattern. (3) The absorbent body in the sanitary article according to claim 1, wherein the wood-loving fiber is a rayon fiber. (4) The fibers constituting the nonwoven fabric have a fineness of 1 to 8 d;
The absorbent body in a sanitary article according to claim 1, wherein the fiber length is 10 m or more. (5) The absorbent body in the sanitary article according to claim 1, wherein the nonwoven fabric has a basis weight of 15 to 60 g/m^2. (6) The sanitary article according to claim 1, wherein the superabsorbent polymer is distributed in the nonwoven fabric in a state in which when it absorbs body fluids and swells, it does not come into continuous contact with the nonwoven fabric to form a body fluid permeation barrier. Absorber. (7) The absorbent body in the sanitary article according to claim 1, wherein the superabsorbent polymer is present in an amount of 20 to 500% of the weight of the polymer and the nonwoven fabric in a dry state. (8) The absorbent body in the sanitary article according to claim 1, wherein the pulp forming the pulverized pulp layer has a fiber length of 5 mm or less. (9) The ground pulp layer has a basis weight of 50 to 300 g/m
The absorbent body in the sanitary article according to claim 1, which is ^2. (10) In the sanitary article according to claim 1, the pulverized pulp is mixed in the fibers of the nonwoven fabric and the superabsorbent polymer at the boundary between the core layer and the pulverized pulp layer. body. (11) The absorbent body in a sanitary article according to claim 1, wherein the pulverized pulp layer is laminated on both sides of the core layer, and the laminate is compressed and integrated in the thickness direction. (12) The absorbent body in the sanitary article according to claim 1, wherein a plurality of the absorbent bodies are laminated. (13) The absorbent body in the sanitary article according to claim 1, wherein the absorbent body is combined with another absorbent material. (14) A nonwoven fabric that maintains its shape by intertwining the fibers and has a vertical striped pattern in which high fiber density areas and low fiber density areas are arranged alternately in the width direction is processed into powder or fiber form in the presence of moisture. forming a core layer by substantially uniformly dispersing a superabsorbent polymer, laminating a pulverized pulp layer on at least one surface of the core layer, and compressing this laminate in the thickness direction. and a step of making the superabsorbent polymer sticky with the moisture to bond the polymer to the nonwoven fabric, and integrating the laminated state of the core layer and the pulverized pulp layer. A method for manufacturing an absorbent material for sanitary articles. (15) The nonwoven fabric is laminated on the pulverized pulp layer, the superabsorbent polymer is sprinkled on the nonwoven fabric, and water is applied to the nonwoven fabric or the polymer in the process from laminating the nonwoven fabric to after spraying the polymer. 15. The method for producing an absorbent material for sanitary articles according to claim 14, which comprises the step of spraying the polymer in an amount of 15% or less of the weight thereof to make the polymer exhibit adhesiveness. (16) The method for manufacturing an absorbent body in a sanitary article according to claim 14, wherein the compression is performed by embossing arranged in an appropriate pattern. (17) The method for manufacturing an absorbent body in a sanitary article according to claim 14, wherein the hydrophilic fiber is a rayon fiber. (18) The fibers constituting the nonwoven fabric have a fineness of 1 to 8 d.
15. The method for producing an absorbent body in a sanitary article according to claim 14, wherein the fiber length is 10 mm or more. (19) The method for manufacturing an absorbent body in a sanitary article according to claim 14, wherein the nonwoven fabric has a basis weight of 15 to 60 g/m^2. (20) The method for manufacturing an absorbent body in a sanitary article according to claim 14, wherein the nonwoven fabric is formed by a fiber entanglement treatment using high-speed liquid jetting, and the fibers are intertwined with each other in a three-dimensional direction. (21) The absorbent material in the sanitary article according to claim 14, wherein the superabsorbent polymer absorbs body fluids and, when swollen, is distributed in the nonwoven fabric in a state in which it continuously contacts and does not form a body fluid permeation barrier. manufacturing method. (22) The superabsorbent polymer accounts for 20 to 500% of the weight of the nonwoven fabric in the dry state of the polymer and the nonwoven fabric.
A method for manufacturing an absorbent body in a sanitary article according to claim 14, wherein the absorbent body is present in a sanitary article according to claim 14. (23) The method for producing an absorbent body in a sanitary article according to claim 14, wherein the pulverized pulp layer has a fiber length of 5 mm or less. (24) The ground pulp layer has a basis weight of 50 to 300 g/
A method for manufacturing an absorbent body in a sanitary article according to claim 14, wherein the absorbent body is m^2. (25) At the boundary between the core layer and the pulverized pulp layer, the pulverized pulp is mixed in the fibers of the nonwoven fabric and the superabsorbent polymer by laminating and compressing them. Method for manufacturing absorbent material in sanitary articles. (26) The method for manufacturing an absorbent body in a sanitary article according to claim 14, wherein the pulverized pulp layer is laminated on both sides of the core layer, and the laminate is compressed and integrated in the thickness direction.