Absorbent diffusion sheet and absorbent article containing the sheet

Abstract

To address the conventional requirement for functions of an absorber used for absorbent articles such as paper diapers, sanitary products and absorbent shorts, the functions of quickly absorbing body fluids and of preventing back flow and seeping-through thereof caused by pressure application, etc., in which various proposals have been made to meet the requirement and have been effective to a certain extent; however, further improvement is required to meet advanced requirement, and to provide a sheet having a high absorption rate, and suppressing the back flow and the seeping-through.SOLUTION: An absorbing / diffusing sheet comprises: a laminated nonwoven fabric including a permeable layer on a front side, and an absorbing / diffusing layer on a back side, where a ratio of a specific volume of the absorbing / diffusing layer to a specific volume of the laminated nonwoven fabric is 0.1 to 1.0 and a ratio of a diffusion area of the absorbing / diffusing layer to a diffusion area of the permeable layer is 4.0 to 15.0; and a laminate layer on the back side of the laminated nonwoven fabric.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an absorbent-diffusion sheet having high water absorption, permeability, diffusion and drying properties, and an absorbent article comprising said nonwoven fabric. In particular, the present invention relates to an absorbent-diffusion sheet that can quickly absorb body fluids and suppress backflow when used in absorbents for absorbent articles such as disposable diapers, sanitary products, absorbent shorts, nursing care sheets, bed pads, sweat-absorbing pads for helmets and clothing, and pet sheets. [Background technology]

[0002] 2. Description of the Related Art Absorbents used in absorbent articles such as disposable diapers, sanitary napkins, and absorbent shorts have traditionally been required to have the ability to quickly absorb body fluids and not flow back when pressurized, and various proposals have been made to meet this requirement.

[0003] For example, Patent Document 1 discloses an absorbent article having an absorbent body sandwiched between a bodily fluid permeable surface material and a bodily fluid impermeable back material, the absorbent body having an upper layer and a lower layer, in that order from the surface material side, and the density of the lower layer being higher than the density of the upper layer.

[0004] Patent Document 2 discloses an absorbent body for use in absorbent articles, comprising a second nonwoven fabric and a first nonwoven fabric laminated on the surface of the second nonwoven fabric, the first nonwoven fabric containing 70% by mass or more of first cellulose fibers having a fineness greater than the average fineness of the constituent fibers of the second nonwoven fabric and not greater than 3.0 dtex, and the second nonwoven fabric containing 70% by mass or more of second regenerated cellulose fibers having a fineness smaller than the average fineness of the constituent fibers of the first nonwoven fabric and having a fineness of 0.2 to 1.0 dtex.

[0005] Although the technologies of Patent Document 1 and Patent Document 2 have been effective to a certain extent in the problem of rapid absorption of bodily fluids and suppression of backflow, they do not fully meet advanced requirements. In this regard, the inventors have found that in a laminated nonwoven fabric having a permeation layer and an absorption / diffusion layer, the specific volume of the absorption / diffusion layer is made half or less of the specific volume of the laminated nonwoven fabric, that is, the specific volume of the absorption / diffusion layer is made significantly smaller than the specific volume of the permeation layer, so that the liquid that has infiltrated from the permeation layer side quickly passes through the permeation layer, is diffused over a wide area at the interface between the permeation layer and the absorption / diffusion layer, is absorbed, and backflow is greatly suppressed. Patent applications have been filed for Patent Application Nos. 2022-175426 and 2022-175427. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2004-121382 A [Patent Document 2] JP 2016-022173 A Summary of the Invention [Problem to be solved by the invention]

[0007] The inventions described in Patent Application Nos. 2022-175426 and 2022-175427 are highly effective in suppressing backflow, but there is room for improvement in preventing absorbed liquid from penetrating the absorption and diffusion layer and leaking out the back side (hereinafter referred to as "run-through"). The present invention was devised in view of the current state of the prior art, and its purpose is to provide a sheet that has a high absorption rate, suppresses backflow, and also suppresses run-through. [Means for solving the problem]

[0008] As a result of intensive research to achieve the above-mentioned object, the inventors have arrived at the present invention by suppressing strike-through by providing a laminate layer on the back side of a laminated nonwoven fabric consisting of a permeable layer and an absorbing and diffusing layer, in addition to controlling the specific volume in the inventions described in the above-mentioned Patent Applications No. 2022-175426 and No. 2022-175427.

[0009] That is, the present invention is achieved by the following means. (1) An absorbing / diffusing sheet comprising a laminated nonwoven fabric having a permeable layer on its front side and an absorbing / diffusing layer on its back side, the ratio of the specific volume of the absorbing / diffusing layer to the specific volume of the laminated nonwoven fabric being 0.1 to 1.0, and the ratio of the diffusion area of ​​the absorbing / diffusing layer to the diffusion area of ​​the permeable layer being 4.0 to 15.0, and a laminate layer being provided on the back side of the laminated nonwoven fabric. (2) The absorbent-diffusion sheet according to (1), characterized in that the laminated nonwoven fabric uses a needle-punched nonwoven fabric or card web as the permeable layer and a needle-punched nonwoven fabric as the absorbent-diffusion layer, and these are integrated together by a needle-punch method. (3) The absorbing-diffusing sheet according to (2), wherein the total penetration number of the permeable layers is 1 / 6 to 1 / 2 of the total penetration number of the absorbing-diffusing layers. (4) The absorbing / diffusing sheet according to (1), wherein the permeable layer contains 50 to 100% by mass of hydrophobic fibers, and the absorbing / diffusing layer contains 50 to 100% by mass of hydrophilic fibers. (5) The absorbing / diffusing sheet according to (1), wherein the absorbing / diffusing layer contains at least one of a deodorant fiber and an antibacterial fiber. (6) The absorbing / diffusing sheet according to (1), wherein the absorbing / diffusing layer contains 5 to 50% by mass of acrylate fibers. (7) The absorbing / diffusing sheet according to (1), wherein the absorbing / diffusing layer contains 5 to 50% by mass of antibacterial acrylic fibers. (8) The absorbing / diffusing sheet according to (1), wherein the laminate layer has moisture permeability. (9) The absorbing / diffusing sheet according to (1), wherein the laminated nonwoven fabric has a diffusion auxiliary layer between the transmitting layer and the absorbing / diffusing layer. (10) An absorbent article in which the absorbent-diffusion sheet according to any one of (1) to (9) is incorporated so as to absorb liquid from the front side of the sheet. Effect of the Invention

[0010] The absorbent-diffusion sheet of the present invention has a high absorption rate for bodily fluids such as menstrual blood and urine, and is suppressed from backflowing and striking through. The absorbent-diffusion sheet of the present invention having such properties can be suitably used as an absorbent for, for example, sanitary napkins, paper diapers, incontinence liners, sanitary shorts, nursing care sheets, bed pads, sweat-absorbing pads for helmets and clothing, pet sheets, and the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described in detail below. The laminated nonwoven fabric used in the absorbing / diffusing sheet of the present invention has a permeable layer on the front side and an absorbing / diffusing layer on the back side. In such a nonwoven fabric, the specific volume of the absorbing / diffusing layer is made much smaller than the specific volume of the permeable layer. Specifically, the ratio of the specific volume of the absorbing / diffusing layer to the overall specific volume of the laminated nonwoven fabric is 0.1 to 1.0, preferably 0.1 to 0.8, more preferably 0.1 to 0.7, and even more preferably 0.1 to 0.6.

[0012] Here, when the ratio of the specific volume of the absorbing-diffusion layer to the overall specific volume of the laminated nonwoven fabric (i.e., the specific volume of the integrated permeable layer and absorbing-diffusion layer) is 1, the specific volumes of the permeable layer and the absorbing-diffusion layer are the same; when this ratio of specific volumes is greater than 1, the specific volume of the absorbing-diffusion layer is greater than that of the permeable layer; and when this ratio of specific volumes is less than 1, the specific volume of the absorbing-diffusion layer is smaller than that of the permeable layer.

[0013] If the ratio of specific volumes is less than 0.1, the specific volume is made very small by applying high pressure during the calendaring process when the absorbing / diffusing layer is produced, which may cause tears or holes in the absorbing / diffusing layer during this process, or may cause tears or holes during the subsequent needle punching process for laminating with the permeable layer. On the other hand, if the ratio exceeds 1.0, the structure of the absorbing / diffusing layer becomes too sparse, resulting in poor diffusibility of body fluids, and therefore, when the layer is used in an absorbent article, the absorbed body fluids may be localized in the absorbing / diffusing layer and not be retained, resulting in a large amount of backflow or leakage.

[0014] The specific volume of the laminated nonwoven fabric is preferably 10 to 25 cm 3 / g, more preferably 14 to 20 cm 3 / g. The specific volume of the laminated nonwoven fabric is 10 cm 3 If the specific volume of the laminated nonwoven fabric is less than 25 cm3 / g, the permeable layer will be thin, and the distance from the surface of the permeable layer to the absorbing and diffusing layer will be short, which will easily cause problems such as backflow and leakage. 3 If it exceeds 1 / g, the bulkiness will be too high, and when used in absorbent articles and the like, there is a risk of causing discomfort when worn.

[0015] The specific volume of the absorbing / diffusing layer is preferably 3 to 15 cm 3 / g, preferably 5 to 13 cm 3 / g. The specific volume of the absorbing and diffusing layer is 3 cm 3 If the specific volume of the absorbing / diffusing layer is less than 15 cm, high pressure is applied during the calendaring process to prepare the absorbing / diffusing layer, which may cause tears or holes in the absorbing / diffusing layer during the process, or tears or holes may also occur during the needle punching process to laminate the layer with the permeable layer. 3 If it exceeds this value, the structure becomes too sparse to allow body fluids to be diffused sufficiently, and the amount of body fluid that has little interaction with the constituent fibers of the absorbent-diffusion layer increases, which may result in backflow or leakage.

[0016] Furthermore, the thickness of the absorption-diffusion layer is preferably 0.4 to 1.5 mm, more preferably 0.5 to 1.0 mm. If the thickness of the absorption-diffusion layer exceeds 1.5 mm, the structure becomes too sparse, so that the body fluid is not sufficiently diffused, and the amount of body fluid that has little interaction with the constituent fibers of the absorption-diffusion layer increases, which may cause backflow or leakage. On the other hand, in order to make the thickness of the absorption-diffusion layer smaller than 0.4 mm, in addition to applying high pressure by calendaring, there is also a method of using a large amount of heat-fusible fibers in the absorption-diffusion layer, but the texture becomes hard and the layer is not suitable for applications such as absorbent articles.

[0017] In the laminated nonwoven fabric described above, the ratio of the diffusion area of ​​the absorbing / diffusing layer to the diffusion area of ​​the permeable layer, determined by the method described below, is 4.0 to 15.0, preferably 5.0 to 15.0. If the diffusion area ratio is less than 4.0, the diffusion of bodily fluids in the absorbing / diffusing layer becomes insufficient, and bodily fluids are retained locally in the absorbing / diffusing layer, which may cause backflow or leakage. On the other hand, if the diffusion area ratio exceeds 15.0, lateral leakage may occur from the side of the laminated nonwoven fabric.

[0018] The above-mentioned permeable layer and absorbing / diffusing layer may be made of a thermally bonded nonwoven fabric, a chemically bonded nonwoven fabric, a spunlace nonwoven fabric, a needle-punched nonwoven fabric, a card web, or the like. The permeable layer is preferably a needle-punched nonwoven fabric or a card web from the viewpoint of forming a soft touch, and more preferably a card web because it is easy to increase the specific volume and reduce manufacturing costs. The absorbing / diffusing layer is preferably a needle-punched nonwoven fabric from the viewpoint of reducing the specific volume to a certain extent and preventing the layer from becoming too hard. The "card web" refers to a thin-film fiber sheet made by simply passing cotton-like fibers through a carding machine.

[0019] In the laminated nonwoven fabric used in the present invention, the above-mentioned permeable layer and absorbing / diffusing layer are preferably integrated by a needle punching method. The total penetration number of the permeable layer is preferably 1 / 6 to 1 / 2, and more preferably 1 / 4 to 1 / 2, of the total penetration number of the absorbing / diffusing layer. Here, the penetration number is the number of holes per cm in the needle punching method. 2 The total penetration number refers to the number of needles per layer, and the total penetration number refers to the sum of the penetration number at the stage of making each layer and the penetration number at the stage of integrating these layers. Therefore, in the manufacturing method described below, the smaller the ratio of the total penetration number of the permeable layer to the total penetration number of the absorbent-diffusing layer, the smaller the penetration number at the stage of integration. If the ratio of the total penetration number is less than 1 / 6, the penetration number at the stage of integration is too small, and there is a risk that the permeable layer and the absorbent-diffusing layer will separate during processing into a product or during use. On the other hand, if the ratio of the total penetration number exceeds 1 / 2, the penetration number at the stage of integration is too large, the surface of the absorbent-diffusing layer becomes fuzzy and the smoothness is reduced, and the boundary between the permeable layer and the absorbent-diffusing layer becomes blurred, so that the diffusion of body fluids in the absorbent-diffusing layer may be insufficient.

[0020] Furthermore, when integrating the permeable layer and the absorbing / diffusing layer by the needle punch method, it is desirable to make the needle depth as shallow as possible within the range that allows integration. The deeper the needle depth, the more the surface of the absorbing / diffusing layer becomes fluffy and less smooth, and the more the boundary between the permeable layer and the absorbing / diffusing layer becomes blurred, which may result in insufficient diffusion of bodily fluids in the absorbing / diffusing layer.

[0021] In addition, in the above-mentioned permeable layer, from the viewpoint of allowing body fluids to pass through quickly without diffusing, the constituent fibers preferably contain hydrophobic fibers at 50 to 100% by mass, more preferably 70 to 100% by mass. As such fibers, general hydrophobic fibers can be used. For example, polyester fibers, polypropylene fibers, or acrylic fibers can be used. From the viewpoint of maintaining the shape, 5 to 20% by mass of heat-fusible fibers such as low-melting polyester fibers and polypropylene / polyethylene core-sheath fibers may be used in combination. The permeable layer may be composed of only hydrophobic fibers, but from the viewpoint of providing functions and improving texture, fibers other than hydrophobic fibers may be used in combination within a range in which sufficient permeability can be obtained.

[0022] The fineness of the hydrophobic fiber used in the permeable layer is preferably 2 to 11 dtex, more preferably 3 to 8 dtex, from the viewpoint of expressing a fluffy touch. Among them, the use of hollow fibers with a higher fineness is more preferable because it allows the permeable layer to maintain a fluffy feel even after repeated pressure application.

[0023] In addition, in the above-mentioned absorption-diffusion layer, from the viewpoint of improving the absorption and diffusion properties, the constituent fibers preferably contain hydrophilic fibers in an amount of 50 to 100% by mass, more preferably 70 to 90% by mass. Examples of such fibers include cellulose-based fibers such as cotton and rayon, acrylate-based fibers, and water-absorbent acrylic fibers. The acrylate-based fibers are fibrous carboxyl group-containing polymers, and can be obtained by subjecting acrylic fibers to a crosslinking treatment using a crosslinking agent such as hydrazine and a hydrolysis treatment using an alkaline metal compound such as sodium hydroxide. Specific examples include "Ex (registered trademark)" and "Moisture Care (registered trademark)" manufactured by Toyobo Co., Ltd., "Sunburner (registered trademark)" manufactured by Teijin Frontier Co., Ltd., and hygroscopic fibers disclosed in JP-A-05-132858 and JP-A-2000-314082.

[0024] The fineness of the hydrophilic fibers used in the above-mentioned absorbing and diffusing layer is preferably 1 to 5 dtex, more preferably 1 to 4 dtex, from the viewpoint of maintaining a high density shape in needle punching.

[0025] In addition, since the absorption / diffusion layer retains body fluids, it is preferable to use a deodorant fiber or an antibacterial fiber in combination. Examples of such fibers include acrylate fibers, antibacterial acrylic fibers, and rayon kneaded with chitosan. In particular, acrylate fibers are suitable because they are highly hydrophilic. In the case where a deodorant fiber or an antibacterial fiber is used in combination in the absorption / diffusion layer, the content of these fibers is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, from the viewpoint of sufficiently obtaining the desired performance.

[0026] Furthermore, the absorbing / diffusing layer may be subjected to a calendaring process to reduce the specific volume. In this case, if 5% by mass or more of heat-fusible fibers are used in the absorbing / diffusing layer, the heat-fusible fibers are heat-fused during the calendaring process, making it easier to reduce the specific volume. However, if more than 20% by mass of heat-fusible fibers are used, the texture may become too hard, which may cause a poor wearing experience when used in absorbent articles.

[0027] Examples of the heat-fusible fibers include low-melting polyester fibers and polypropylene / polyethylene core-sheath fibers. In addition, from the viewpoint of not impeding the absorption of body fluids in the absorption / diffusion layer, those having hydrophilic properties are preferable.

[0028] Next, the laminate layer used in the absorbent-diffusion sheet of the present invention can be provided by producing the above-mentioned laminated nonwoven fabric and then laminating the surface of the laminated nonwoven fabric on the absorbent-diffusion layer side. There are no particular limitations on the material for the laminate layer, and polyethylene, polypropylene, polyester, polyurethane, etc. can be used. Among them, polyurethane is suitable because it has both elasticity and moisture permeability, and when used as an absorbent article, it is easy to follow the movement and is expected to reduce stuffiness.

[0029] The thickness of the laminate layer is preferably 5 to 30 μm, more preferably 7 to 20 μm. If it is less than 5 μm, the suppression of strike-through is insufficient, and if it exceeds 20 μm, the texture becomes too hard, which may deteriorate the wearing comfort when used in absorbent articles, etc.

[0030] There is no particular limitation on the lamination method, and any conventionally known method can be used, such as an extrusion lamination method in which a molten resin film extruded from a T-die is continuously coated and pressed onto a laminated nonwoven fabric, or a dry lamination method in which a laminate film is attached to a laminated nonwoven fabric with an adhesive or the like.

[0031] In addition, the absorbent-diffusion sheet of the present invention may have a diffusion auxiliary layer between the permeable layer and the absorbent-diffusion layer constituting the laminated nonwoven fabric. By providing such a diffusion auxiliary layer, the body fluid that has infiltrated from the permeable layer side can be diffused more quickly over a wide area. The thickness of such a diffusion auxiliary layer is preferably 0.3 to 1.5 mm, more preferably 0.4 to 0.8 mm. If the thickness is less than 0.3 mm, there is a risk of tears or holes being generated during needle punch processing for laminating the layers. On the other hand, if the thickness exceeds 1.5 mm, the entire laminated nonwoven fabric may have a hard texture, which may make it unsuitable for use in absorbent articles, etc.

[0032] Furthermore, in order to improve the diffusibility, the diffusion-assisting layer preferably has a basis weight of 30 to 60 g / m 2 and more preferably 40 to 50 g / m 2 The constituent fibers preferably contain hydrophilic fibers at 50 to 100% by mass. Examples of such hydrophilic fibers include cellulosic fibers such as cotton and rayon, and it is particularly preferable to use rayon. The fineness is preferably 0.8 to 2.0 dtex, and more preferably 1.0 to 1.7 dtex. As the diffusion-assisting layer, a rayon spunlace nonwoven fabric or the like can be used.

[0033] The absorbing / diffusing sheet of the present invention can be manufactured, for example, as follows. First, for the absorbing / diffusing layer, a card web made of the fibers constituting the absorbing / diffusing layer is produced, followed by needle punching and calendaring to obtain a needle-punched nonwoven fabric with a reduced specific volume. Next, a card web containing the fibers constituting the permeable layer is overlaid on the needle-punched nonwoven fabric, and needle punching is performed again to obtain a laminated nonwoven fabric. The absorbing / diffusing layer side of the laminated nonwoven fabric is laminated to obtain the absorbing / diffusing sheet of the present invention.

[0034] The above-mentioned absorbent-diffusion sheet of the present invention can be suitably used as an absorbent for absorbent articles such as sanitary napkins, paper diapers, incontinence liners, sanitary shorts, nursing care sheets, bed pads, sweat-absorbing pads for helmets and clothing, pet sheets, etc. When used for such purposes, it is desirable to incorporate the nonwoven fabric into the absorbent article so that it absorbs liquid from the front side.

[0035] In addition, when used as an absorbent for an absorbent article, another layer may be provided on the surface of the absorbing / diffusing sheet of the present invention, or a functional agent may be coated or supported on the surface, taking into consideration the characteristics required for the absorbent article. When providing a surface material, the surface material and the laminated nonwoven fabric may first be quilted, and then the back side may be laminated. In this way, the seams created by the quilting process can be sealed with the laminate layer. EXAMPLES

[0036] Examples are shown below to facilitate understanding of the present invention, but these are merely illustrative and the gist of the present invention is not limited thereto. The methods for evaluating each characteristic are as follows.

[0037] <Specific volume ratio in laminated nonwoven fabric> For the absorption-diffusion layer before integration and the nonwoven fabric after lamination (laminate nonwoven fabric), the thickness and mass per unit area are determined in accordance with the test methods in "6.1 Thickness" and "6.2 Mass per unit area" of JIS L 1913:2010, and the specific volume is calculated from the thickness and mass per unit area, and the specific volume ratio is calculated using the following formula. (Formula) Specific volume ratio = specific volume of absorption / diffusion layer / specific volume of laminated nonwoven fabric

[0038] <Diffusion area ratio in laminated nonwoven fabric> 0.2 ml of a red aqueous liquid (a 0.1% by mass aqueous solution of Cathilon Red K-GRL manufactured by Nissei Chemical Industries, Ltd.) was dropped onto the front side (transmitting layer side) of the sample, and after leaving it for 1 minute, an acrylic plate of the same shape as the sample and a weight were placed on it to measure 12.5 g / cm 2 A pressure of 10 ... (Formula) Diffusion area ratio [times] = M1 / M0

[0039] <Reversibility> 2 ml of water was dropped onto the front side (transmitting layer side) of a rectangular sample measuring 6.5 cm x 7 cm placed on an acrylic plate, and after leaving it for 1 minute, an acrylic plate of the same shape as the sample and a weight of 25 g / cm were placed on the sample. 2 A pressure of 10 ... 3 points: No dampness 2 points: Feels damp 1 point: Feels wet 0 points: Wet

[0040] <Back-bleed rate> 2 ml of water was dropped onto the front side (transmitting layer side) of a rectangular sample measuring 6.5 cm x 7 cm placed on an acrylic plate, and after leaving it for 1 minute, an acrylic plate of the same shape as the sample and a weight of 25 g / cm were placed on the sample. 2 Next, remove the acrylic plate and weight from the sample, place five sheets of filter paper (total mass M2) of the same shape as the sample under the sample, and then place the acrylic plate and weight on top of the sample to obtain a pressure of 25 g / cm. 2 A pressure of 1000 μm is applied for 1 minute. Next, the total mass (M3) of the five sheets of filter paper after water absorption is measured. The strike-through rate [%] is calculated from the obtained measured value by the following formula. When the filter paper is used in an absorbent article, the strike-through rate is preferably less than 10%, more preferably less than 5%, and even more preferably less than 2%. (Formula) Strike-through rate [%] = (M3-M2) / 2 x 100

[0041] <Deodorizing properties> An ammonia deodorizing test was conducted in accordance with the deodorizing test (detector tube method) of the SEK Mark Textile Product Certification Standard (JEC301) (General Incorporated Association Japan Textile Evaluation Technology Council), and the reduction rate of odorous components after 2 hours was measured.

[0042] <Antibacterial> The antibacterial activity value against Staphylococcus aureus was measured according to the bacterial liquid absorption method of JIS L 1902. The certification standard for the SEK mark antibacterial and deodorant finish is an antibacterial activity value of 2.2 or more.

[0043] [Example 1] <Preparation of absorption / diffusion layer> A mixture of 60 parts by mass of rayon fiber (Corona manufactured by Daiwabo Co., Ltd., fineness 1.45 dtex, fiber length 51 mm), 25 parts by mass of an acrylate fiber having deodorant properties (Moist Care (registered trademark) manufactured by Toyobo Co., Ltd., fineness 4.4 dtex, fiber length 50 mm) and 15 parts by mass of an antibacterial acrylic fiber (Ginsekai (registered trademark) manufactured by Toyobo Co., Ltd., fineness 2.2 dtex, fiber length 51 mm) was used to produce a fabric with a basis weight of 80 g / m. 2A needle-punched nonwoven fabric was produced by entangling the carded web with a needle punch at a penetration number of 50. The nonwoven fabric was then calendered using a steel / steel calendering machine under conditions of a pressure of 7 MPa, a temperature of 140°C, and a speed of 3.0 m / min to produce an absorbing / diffusing layer having the thickness, basis weight, and specific volume shown in Table 1.

[0044] <Preparation of Absorbing and Diffusing Sheet> 90 parts by weight of polyester fiber (fineness 3.3 dtex, fiber length 51 mm) and 10 parts by weight of low-melting-point polyester fiber (manufactured by Hubis, core-sheath structure with regular polyester core and sheath with low-melting-point polyester, fineness 4.4 dtex, fiber length 51 mm) were mixed to obtain a fabric with a basis weight of 50 g / m 2 A card web (transmissive layer) was prepared with the above-mentioned absorbing / diffusing layer as the target. The card web was then overlapped with the above-mentioned absorbing / diffusing layer, and the card web side was needle-punched to a penetration number of 50, followed by heat treatment at 140°C for 5 minutes to produce a laminated nonwoven fabric. A urethane resin film (thickness 10 μm) was attached to the absorbing / diffusing layer side of the obtained laminated nonwoven fabric with a urethane resin adhesive by dry lamination processing, thereby obtaining an absorbing / diffusing sheet of Example 1. The evaluation results of the obtained laminated nonwoven fabric and absorbing / diffusing sheet are shown in Table 1.

[0045] [Example 2] <Preparation of absorption / diffusion layer> A mixture of 50 parts by mass of rayon fiber (manufactured by Lenzing, fineness 1.7 dtex, fiber length 51 mm), 25 parts by mass of deodorant acrylate fiber (manufactured by Toyobo Co., Ltd., "Moist Care (registered trademark)", fineness 4.4 dtex, fiber length 50 mm), 15 parts by mass of antibacterial acrylic fiber (manufactured by Toyobo Co., Ltd., "Ginsekai (registered trademark)", fineness 2.2 dtex, fiber length 51 mm), and 10 parts by mass of polyethylene / polypropylene core-sheath type heat-fusible fiber (manufactured by JNC Fiber Co., Ltd., ESC012, fineness 1.7 dtex, fiber length 51 mm) was produced with a basis weight of 80 g / m. 2A needle-punched nonwoven fabric was produced by entangling the carded web with a needle punch at a penetration number of 160. The nonwoven fabric was then calendered using a steel / rubber roll calendering machine under conditions of a pressure of 4 MPa, a temperature of 160°C, and a speed of 4.0 m / min to produce an absorbing / diffusing layer having the thickness, basis weight, and specific volume shown in Table 1.

[0046] <Preparation of Absorbing and Diffusing Sheet> 90 parts by mass of hollow polyester fiber (Teijin Frontier RA94F, fineness 6.6 dtex, fiber length 51 mm) and 10 parts by mass of low melting point polyester fiber (Far East New Century SN3450CM, fineness 4.0 dtex, fiber length 51 mm) were mixed to produce a fabric with a basis weight of 40 g / m 2 A card web (transmitting layer) is produced with the target. The card web and the above-mentioned absorbing / diffusing layer are overlapped and entangled by needle punching with a penetration number of 60 from the card web side. Next, a laminated nonwoven fabric is produced by heating from the absorbing / diffusing layer side under conditions of pressure 0 MPa (open state), temperature 160°C, and speed 4.0 m / min using a steel / rubber roll calendaring machine. A urethane resin film (thickness 10 μm) is attached to the absorbing / diffusing layer side of the obtained laminated nonwoven fabric with a urethane resin adhesive by dry lamination processing, and an absorbing / diffusing sheet of Example 2 is obtained. The evaluation results of the obtained laminated nonwoven fabric and absorbing / diffusing sheet are shown in Table 1.

[0047] [Example 3] An absorbing / diffusing sheet of Example 3 was produced in the same manner as in Example 1, except that the pressure condition in the calendaring process for producing the absorbing / diffusing layer was 1 MPa. The evaluation results of the obtained laminated nonwoven fabric and absorbing / diffusing sheet are shown in Table 1.

[0048] [Comparative Example 1] An absorbing / diffusing sheet of Comparative Example 1 was produced in the same manner as in Example 1, except that the pressure condition in the calendaring process during the production of the absorbing / diffusing layer was 0 MPa (open state). The evaluation results of the obtained laminated nonwoven fabric and absorbing / diffusing sheet are shown in Table 1.

[0049] [Comparative Example 2] The evaluation results of the laminated nonwoven fabric in Example 2 (that is, the laminated nonwoven fabric not subjected to lamination processing) are shown in Table 1.

[0050] [Reference example 1] A nonwoven fabric of Reference Example 1, which has the same constituent fibers as the transmission layer in Example 1, was prepared in the same manner as in the preparation of the laminated nonwoven fabric in Example 1 <Preparation of Absorbent-Diffusion Sheet>, except that the absorbent-diffusion layer was not overlapped.

[0051] [Reference example 2] A nonwoven fabric of Reference Example 2, which has the same constituent fibers as the transmission layer in Example 2, was prepared in the same manner as in the preparation of the laminated nonwoven fabric in Example 2 <Preparation of Absorbent-Diffusion Sheet>, except that the absorbent-diffusion layer was not overlapped.

[0052] [Table 1]

[0053] As can be seen from Table 1, the absorbent-diffusing sheets of Examples 1 to 3 of the present invention have the characteristics of suppressing backflow and greatly suppressing strike-through. In contrast, Comparative Example 1, in which the specific volume ratio and diffusion area ratio are outside the range of the present invention, was evaluated as having low backflow and was not suitable for use in absorbent articles. In Comparative Example 2, which does not have a laminate layer, the strike-through rate is high, and it is necessary to use a waterproof cloth or the like in combination when using it in absorbent articles.

Claims

1. An absorbing / diffusing sheet comprising a laminated nonwoven fabric having a permeable layer on its front side and an absorbing / diffusing layer on its back side, the ratio of the specific volume of the absorbing / diffusing layer to the specific volume of the laminated nonwoven fabric being 0.1 to 1.0, and the ratio of the diffusion area of ​​the absorbing / diffusing layer to the diffusion area of ​​the permeable layer being 4.0 to 15.0, and a laminate layer being provided on the back side of the laminated nonwoven fabric.

2. 2. The absorbing and diffusing sheet according to claim 1, characterized in that the laminated nonwoven fabric uses a needle-punched nonwoven fabric or card web as the permeable layer and a needle-punched nonwoven fabric as the absorbing and diffusing layer, which are integrated together by a needle-punching method.

3. 3. The absorbing-diffusing sheet according to claim 2, wherein the total penetration number of the transmission layer is 1 / 6 to 1 / 2 of the total penetration number of the absorbing-diffusing layer.

4. 2. The absorbing / diffusing sheet according to claim 1, wherein the permeable layer contains 50 to 100% by mass of hydrophobic fibers, and the absorbing / diffusing layer contains 50 to 100% by mass of hydrophilic fibers.

5. 2. The absorbing and diffusing sheet according to claim 1, wherein the absorbing and diffusing layer contains at least one of a deodorant fiber and an antibacterial fiber.

6. 2. The absorbing / diffusing sheet according to claim 1, wherein the absorbing / diffusing layer contains 5 to 50% by mass of acrylate fibers.

7. 2. The absorbing and diffusing sheet according to claim 1, wherein the absorbing and diffusing layer contains 5 to 50% by mass of antibacterial acrylic fibers.

8. 2. The absorbing and diffusing sheet according to claim 1, wherein the laminate layer has moisture permeability.

9. 2. The absorbing / diffusing sheet according to claim 1, wherein the laminated nonwoven fabric has a diffusion auxiliary layer between the transmission layer and the absorbing / diffusing layer.

10. 10. An absorbent article comprising the absorbent-diffusion sheet according to claim 1 incorporated therein so as to absorb liquid from the front side of the sheet.