JP2008161278A - Absorbent article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorbent article which includes a surface sheet showing excellent concealing performance and a bulkiness retaining property. <P>SOLUTION: The surface sheet disposed in the absorbent article includes a composite fiber 100 containing a particulate light transmission suppressing agent 150 for suppressing the transmission of light. The composite fiber 100 contained in the surface sheet includes a core part 110 and a sheath part 120 which covers the entire or a part of the core part 110 and composed of a component having a melting point lower than the core part 110. The content rate of the light transmission suppressing agent 150 in the sheath part 120 is higher than that of the light transmission suppressing agent 150 in the core part 110. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an absorbent article, a sheet used for the absorbent article, and a composite fiber contained in the sheet.

  Conventionally, for example, absorbent articles such as sanitary napkins and paper diapers have an absorbent layer made of cotton-like pulp, absorbent paper, etc., a leak-proof layer disposed on the lower and side surfaces of the absorbent layer, and the surface of the absorbent layer. A basic structure is a structure composed of a top sheet to be placed.

  A nonwoven fabric is mainly used as a surface sheet in an absorbent article. The non-woven fabric is used as the top sheet, for example, by applying an oil agent to the surface of the synthetic fiber constituting the non-woven fabric, the surface wetting can be controlled, and moisture can be prevented from being retained inside the fiber. For reasons such as. Thereby, the nonwoven fabric which suppressed the surface stickiness suitably, for example can be arrange | positioned at the body side.

  Examples of the fiber constituting the nonwoven fabric include a composite fiber having a core-sheath structure, in which the sheath part is made of a low melting point synthetic resin. The thermal bond nonwoven fabric formed by forming this composite fiber into a web and treating it with hot air is suitably used for absorbent articles as a nonwoven fabric having a cushioning property due to its bulkiness and good liquid permeability.

  Here, in order to give the consumer a sense of cleanliness, the surface sheet of the absorbent article maintains a white state even after absorption of the body fluid, so that the color of the body fluid that has been transferred to the lower layer is not visible through the surface sheet. Concealment is required.

  Furthermore, the surface sheet of the absorbent article is required to have a function of absorbing excreted body fluid and maintaining the skin surface in a dry state. That is, the surface sheet of the absorbent article is required to have a function of quickly absorbing the excreted body fluid and transferring the liquid to the lower layer side without leaving the body fluid inside the surface sheet. In order to obtain this function, for example, a method of gradually reducing the inter-fiber gap toward the absorbent layer side (for example, the direction away from the skin) in the top sheet and increasing the liquid transfer property by capillary force, or the fiber on the absorbent layer side There is a method of providing a hydrophilicity gradient by making the oil agent highly wet.

  However, in any method, when bulkiness is reduced by applying body fluid absorption or body pressure, it is impossible to maintain body fluid due to an increase in fiber density or to maintain the distance between the absorbent layer and the skin. Problems such as wet skin (rewetting etc.) may occur.

Here, in order to obtain the above-described concealing property, there has been proposed a method for producing a fiber containing a pigment such as titanium dioxide and having excellent flexibility and color (for example, see Patent Document 1).
JP-A-8-291458

  However, the invention of Patent Document 1 uses a pigment having a specific dispersibility to suppress yarn breakage that occurs during fiber production (especially when melt spinning with an extruder). However, it does not favorably improve the concealment property of the nonwoven fabric constituted by the fibers.

  Furthermore, when a pigment such as titanium dioxide is blended with the fibers constituting the nonwoven fabric, the concealing property of the nonwoven fabric is improved, but the bulkiness maintenance property is lowered.

  This invention is made | formed in view of the above subjects, and it aims at providing an absorbent article provided with the surface sheet excellent in concealability and bulkiness maintenance property.

  In the composite fiber having a core-sheath structure in which a light transmission inhibitor is blended, the present inventors reduce the content of the light transmission inhibitor in the core and increase the content of the light transmission inhibitor in the sheath. Thus, the present inventors have found that it is possible to achieve both concealability and bulkiness maintenance in the nonwoven fabric composed of the composite fiber, and have completed the present invention.

  (1) An absorbent article comprising at least a part of a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorber disposed between the top sheet and the back sheet. The top sheet includes a composite fiber containing a particulate light transmission inhibitor that suppresses light transmission, and the composite fiber covers the core part and all or part of the core part, and the core part. And a sheath part made of a component having a lower melting point, and the content of the light transmission inhibitor in the sheath part is higher than the content of the light transmission inhibitor in the core part.

  (2) The absorbent article according to (1), wherein the content of the light transmission inhibitor in the composite fiber is 1% by mass or more.

  (3) The absorbent article according to (1) or (2), wherein the content of the light transmission inhibitor in the core is 4% by mass or less.

  (4) The absorbent article according to any one of (1) to (3), wherein the content of the light transmission inhibitor in the sheath is 10% by mass or less.

  (5) The absorbent sheet according to any one of (1) to (4), wherein the surface sheet has a whiteness difference from a standard white plate of 30 or less and a bulk recovery rate of 50% or more.

  (6) The absorbent article according to any one of (1) to (5), wherein the light transmission inhibitor is an inorganic filler.

  (7) The absorbent article according to any one of (1) to (8), wherein the content of the composite fiber in the top sheet is 20 to 100% by mass.

  (8) An absorbent article sheet used as a surface sheet in an absorbent article, the absorbent article sheet including a composite fiber containing a particulate light transmission inhibitor that suppresses light transmission, The composite fiber has a core part and a sheath part that covers all or part of the core part and has a lower melting point than the core part, and the content of the light transmission inhibitor in the sheath part Is a sheet for absorbent articles which is higher than the content of the light transmission inhibitor in the core.

  (9) A composite fiber for a surface sheet containing a fine particle light transmission inhibitor that suppresses transmission of light used for the surface sheet in an absorbent article, the composite fiber for a surface sheet comprising: a core; A sheath part that covers all or part of the core part and has a melting point lower than that of the core part, and the content of the light transmission inhibitor in the sheath part is the light transmission suppression in the core part. Composite fiber for surface sheet that is higher than the content of the agent.

  ADVANTAGE OF THE INVENTION According to this invention, an absorbent article provided with the surface sheet excellent in concealability and bulkiness maintenance property can be provided.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a plan view of a sanitary napkin that is an example of an absorbent article. FIG. 2 is a cross-sectional view taken along the line XX ′ of the absorbent article in FIG. FIG. 3 is a diagram illustrating the configuration of the composite fiber.

[1] Outline The present invention comprises an absorbent article comprising at least a part of a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body disposed between the top sheet and the back sheet. About. And the surface sheet in this absorptive article is an absorptive article which has concealability by including the composite fiber containing the particulate light transmission inhibitor which controls the transmission of light. Furthermore, the composite fiber contained in the surface sheet has a core part and a sheath part that covers all or part of the core part and has a melting point lower than that of the core part. The content of is adjusted to be higher than the content of the light transmission inhibitor in the core. That is, the bulkiness maintenance in the surface sheet is improved by reducing the content of the light transmission inhibitor in the core part mainly responsible for the strength of the composite fiber, and the content of the light transmission inhibitor in the sheath is increased. This ensures the concealment of the top sheet.

  In order for the surface sheet to obtain sufficient concealability, the content of the light transmission inhibitor in the composite fiber is preferably 1% by mass or more, for example. Moreover, in order to obtain suitable bulkiness maintenance property in a surface sheet, it is preferable that the content rate of the light transmission inhibitor in the core part of a composite fiber is 4 mass% or less, for example. Moreover, when the productivity (for example, fiber web formation process) of composite fiber is considered, it is preferable that the content rate of the light transmission inhibitor in the sheath part of a composite fiber is 10 mass% or less, for example. Moreover, the case where a light transmission inhibitor is not included in the core part of a composite fiber can also be illustrated.

  The content of the composite fiber in the surface sheet is preferably 20 to 100% by mass, and particularly preferably 50 to 100% by mass. Moreover, the surface sheet containing the composite fiber preferably has a whiteness difference of 30 or less from the standard white plate, and preferably has a bulk recovery rate of 50% or more.

  Examples of the light transmission inhibitor contained in the composite fiber include inorganic fillers described later. As this inorganic filler, titanium dioxide etc. can be illustrated, for example.

  And as above-mentioned, sheets, such as a nonwoven fabric containing the said composite fiber, are used suitably as a surface sheet in an absorbent article. Moreover, the said composite fiber is used suitably as a composite fiber which comprises the surface sheet of an absorbent article.

[2] Absorbent article Examples of the absorbent article in the present invention include paper diapers, sanitary napkins, puffs, liners, and the like. In particular, as shown in FIGS. 1 and 2, at least a part of the liquid-permeable top sheet 10, the liquid-impermeable back sheet 20, and the absorber disposed between the top sheet 10 and the back sheet 20. 30 is a vertically long sanitary napkin 1. The sanitary napkin 1 further includes a second sheet 40 between the top sheet 10 and the absorber 30. Then, the top sheet 10, the second sheet 40, and the absorber 30 are pressure-bonded and fixed by a predetermined pressure-bonding process. By the pressure-bonding process, a leak-proof groove 50 that can prevent body fluid excreted in the central region of the sanitary napkin 1 from flowing out to the outer region is formed. Here, in this embodiment, although the surface sheet 10 demonstrates the case where it consists of a single nonwoven fabric, it is not limited to this, You may be comprised by the several nonwoven fabric.

  As shown in FIG. 2 or FIG. 3, the topsheet 10 can be exemplified by a nonwoven fabric including a composite fiber 100 containing a particulate light transmission inhibitor that suppresses light transmission. The composite fiber 100 contained in the topsheet 10 has a core part 110 and a sheath part 120 made of a component having a melting point lower than that of the core part 110, and the content of the light transmission inhibitor 150 in the sheath part 120 is the core. It is higher than the content rate of the light transmission inhibitor 150 in the part 110.

  Below, the structure in the sanitary napkin 1 which is an absorptive article of the present invention is illustrated concretely. Detailed contents of the topsheet 10 and the composite fiber 100 will be described separately.

The absorber 30 that absorbs body fluid or the like that has passed through the topsheet 10 is constituted by, for example, a cushion disposed on the topsheet 10 side and an absorber material. The absorbent material has a function of absorbing and holding a liquid such as menstrual blood, and is preferably bulky, hardly deformed, and has little chemical irritation. For example, the absorber material which consists of a fluffy pulp or an airlaid nonwoven fabric and a superabsorbent polymer can be illustrated. Examples of the fluffy pulp include artificial cellulose fibers such as chemical pulp, cellulose fiber, rayon, and acetate. As an airlaid nonwoven fabric, for example, a nonwoven fabric in which pulp and synthetic fibers are thermally fused or fixed with a binder can be exemplified. Examples of the superabsorbent polymer include starch-based, acrylic acid-based, and amino acid-based particulate or fibrous polymers. As the cushion, for example, a bulky nonwoven fabric or an airlaid pulp sheet is used. As an example of the absorber 30 in which the cushion and the absorbent material are combined, a pulp has a basis weight of 900 g / m ² , a polymer has a basis weight of 20 g / m ² , and a mixture in which the pulp and the polymer are uniformly distributed over the whole has a basis weight. Examples include those wrapped with a tissue of 15 to 30 g / m ² or a liquid-permeable nonwoven fabric. Here, although the shape and structure of the absorber 30 can be changed as necessary, the total amount of absorption of the absorber 30 needs to correspond to the design insertion amount as the absorbent article and the desired application. Further, the size, absorption capacity, etc. of the absorber 30 are changed corresponding to wearers from infants to adults.

  The liquid-impermeable back sheet 20 is made of a material that can prevent excrement absorbed by the absorber 30 from leaking outside. In addition, by using a moisture-permeable material, it is possible to reduce stuffiness at the time of wearing, and to reduce discomfort at the time of wearing. Examples of such a material include a liquid-impermeable film mainly composed of polyethylene, polypropylene, etc., and a composite sheet obtained by laminating a liquid-impermeable film on one side of a nonwoven fabric such as a breathable film or a spunbond. Alternatively, a melt-blown nonwoven fabric having high water resistance or an SMS nonwoven fabric in which a melt-blown nonwoven fabric is sandwiched between strong spunbond nonwoven fabrics may be used.

  The second sheet 40, which is a liquid-permeable sheet disposed between the top sheet 10 and the absorber 30, includes, for example, a resin film having a large number of liquid-permeable holes and a net-like sheet portion having a large number of meshes. A liquid permeable nonwoven fabric or a woven fabric can be exemplified. As the resin film and the net-like sheet portion, those formed of polypropylene, polyethylene, polyethylene terephthalate, or the like can be used. Moreover, as a nonwoven fabric, the spunlace nonwoven fabric formed from cellulose fibers, such as rayon, a synthetic resin fiber, etc., the air through nonwoven fabric formed with the said synthetic resin fiber, etc. can be used. Further, the second sheet 40 serves as a support for the absorbent body 30 and can impart flexibility and form stability to the absorbent body 30.

  The leak-proof groove 50 is formed by continuously forming the crimping portions at a predetermined interval by a predetermined crimping process. The plurality of pressure-bonding portions constituting the leak-proof groove 50 are formed by, for example, a predetermined pressure-bonding process using a heating roller. For example, a roll having a flat surface is applied to the back surface sheet 20 side of the absorbent body 30, and a heating roll having convex portions of a predetermined pattern is applied to the front surface side of the top sheet 10 and subjected to pressure-bonding treatment. Thereby, the linear or curvilinear leak-proof groove recessed from the surface (body side) of the absorbent article to the back sheet 20 side is formed.

  In addition, a gathering member, an adhesive part for positioning to an undergarment, etc. can be suitably arranged. Moreover, the absorbent article which has the said structure is manufactured by arrange | positioning and bonding each structure by a well-known method. For example, the components can be joined to each other with an adhesive such as the above-described pressure-bonding treatment or hot-melt adhesive. Each component is appropriately selected and adjusted so as to satisfy the function required for the absorbent article.

[3] Surface sheet and composite fiber In order to obtain a surface sheet having both good performance and cleanliness as a surface sheet in absorbent articles such as paper diapers and sanitary napkins, for example, an inorganic filler which is a light transmission inhibitor In an embodiment that does not reduce fiber strength. In other words, it is necessary to blend an inorganic filler that is a light transmission inhibitor so that the nonwoven fabric has both concealability and bulkiness maintenance.

  The composite fiber constituting the surface sheet in the present invention is a composite fiber that covers the core part and all or part of the core part. Examples of the composite fibers include so-called core-sheath composite fibers. This core-sheath structure includes not only a concentric core-sheath structure but also an eccentric core-sheath structure. The composite fiber includes not only the sheath portion covering the entire outer surface (outer peripheral surface) of the core portion, but also the sheath portion covering the sheath portion so that a part of the outer surface of the core portion is exposed.

  The composite fiber is adjusted so that the content of the light transmission inhibitor in the sheath (low melting point component) is larger than the content of the light transmission inhibitor in the core (high melting point component) of the composite fiber. Yes. Thereby, while maintaining the bulkiness maintenance property of the nonwoven fabric containing this composite fiber suitably, suitable concealment property is ensured.

  For example, as shown in FIG. 2, the topsheet 10 disposed on the sanitary napkin 1 is a nonwoven fabric including a composite fiber 100 containing a particulate light transmission inhibitor that suppresses light transmission. As shown in FIG. 3, the conjugate fiber 100 included in the top sheet 10 includes a core part 110 and a sheath part 120 made of a component having a melting point lower than that of the core part 110, and light transmission through the sheath part 120. The content rate of the inhibitor 150 is characterized by being higher than the content rate of the light transmission inhibitor 150 in the core part 110.

  An example of the light transmission inhibitor contained in the composite fiber is an inorganic filler. As this inorganic filler, for example, titanium oxide, calcium carbonate, talc, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, aluminum hydroxide, magnesium hydroxide, zinc oxide, oxidation Examples include calcium, alumina, mica, glass powder, shirasu balloon, zeolite, and silicate clay. You may contain these in combination of 2 or more types. In particular, titanium dioxide is generally preferred from the standpoint of processability at the fiber production stage. The average particle diameter of the light transmission inhibitor is preferably in the range of, for example, 0.1 μm to 2 μm, and further 0.2 μm to 1 μm.

  In order to obtain sufficient concealability (whiteness) in the surface sheet, the content of titanium dioxide as a light transmission inhibitor in the composite fiber is preferably 1% by mass or more, and more preferably 2% by mass or less. When the content rate of the light transmission inhibitor in the entire composite fiber is smaller than 1% by mass, the concealability in the surface sheet containing the composite fiber may not be sufficient.

  Here, as described above, titanium dioxide contributes to improving the concealability of the surface sheet. However, when the content of titanium dioxide is increased, the bulkiness maintaining property of the surface sheet may not be sufficiently obtained. Specifically, the titanium dioxide particles contained in the composite fiber serve as a cradle (starting point) in the composite fiber. That is, by including titanium dioxide, the composite fiber is easily broken and the bending rigidity is lowered. Thereby, a surface sheet becomes soft as a whole, and it becomes difficult to maintain bulkiness.

  Further, when the composite fiber is spun and drawn, a space is generated around the titanium dioxide. By creating a space around the titanium dioxide, the composite fiber is more easily bent. Further, the higher the draw ratio in the composite fiber, the larger the space formed around the titanium dioxide, and the composite fiber is easily bent.

  Here, in order to obtain the concealability and bulkiness maintaining property in the surface sheet, when the content of titanium dioxide is the same as the entire composite fiber, the content of titanium dioxide in the sheath portion than the core portion in the composite fiber Higher is preferred. This is because even if the content of titanium dioxide is the same, the core portion contains titanium dioxide densely inside, and the sheath portion contains titanium dioxide dispersed outside and the core portion is easier to break. By becoming. That is, in the composite fiber, it is preferable to decrease the content of titanium dioxide in the core and increase the content of titanium dioxide in the sheath.

  From the above, in order to obtain sufficient bulkiness maintenance (strength) in the surface sheet, the content of titanium dioxide as a light transmission inhibitor in the core of the composite fiber is 4% by mass or less, and further 3% by mass or less. Preferably there is. When the content of the light transmission inhibitor in the core is larger than 4% by mass, the strength of the composite fiber becomes weak, and sufficient bulkiness maintenance may not be obtained in the sheet containing the composite fiber.

  Moreover, when the productivity of the composite fiber which comprises a surface sheet is considered, it is preferable that the content rate of the light transmission inhibitor in the sheath part of a composite fiber is 10 mass% or less, for example. For example, when titanium dioxide, which is a light transmission inhibitor, is contained in the sheath part of the composite fiber, fine irregularities are generated on the fiber surface, so that the inconvenience in the fiber web formation process (for example, wear of the card wire) However, if the content of titanium dioxide contained in the sheath is less than 10% by mass, it can be processed without any particular problem.

  Moreover, the case where the core part of a composite fiber does not contain a light transmission inhibitor can also be illustrated as a suitable aspect. When the core part mainly responsible for the strength of the conjugate fiber does not contain an inorganic filler that is a light transmission inhibitor, the strength of the conjugate fiber is strong, and the sheet such as a nonwoven fabric containing the conjugate fiber is excellent in bulkiness maintenance, It is an example of the most preferable aspect. However, in order to obtain concealability, it is necessary to contain a predetermined amount of a light transmission inhibitor in the sheath. Preferably, in the above-described range, an inorganic filler that is a light transmission inhibitor can be contained.

  Specifically, a non-woven fabric using a core-sheath composite fiber in which the core (high melting point component) is polyester and the sheath (low melting point component) is polyethylene will be described as an example. A composite fiber in which titanium dioxide is blended so that the content of titanium dioxide in the polyester that is the core component of the composite fiber is reduced and the content of titanium dioxide in the polyethylene that is the sheath component is increased, and titanium dioxide Although the total amount in is the same, when compared with the case where titanium dioxide is blended only in the polyester which is the core component, the former is less crushed and is excellent in bulk recovery. Moreover, in the former case, as the content (content ratio) of titanium dioxide in the core component is reduced, the bulkiness is reduced.

Here, the structural example of the material in the core / sheath of a composite fiber is illustrated below. However, the structure of the material in the core / sheath of the composite fiber is not limited to the following.
(1) Polypropylene (PP) / polyethylene resin (polyethylene, ethylene copolymer resin)
(2) Polyester resin (polyethylene terephthalate (PET), polybutylene terephthalate (PBT), or a blend thereof) / polyethylene resin (3) polyamide resin (6,66 nylon, etc.) / Polyethylene resin (4) polyester Resin / low melting point PET resin (5) polyester resin / polyester resin

  In the above, the polyethylene resin is high density (HDPE), medium density (MDPE), low density (LDPE), very low density (SLDPE), linear low density (LLDPE), etc., and ethylene copolymer resin is ethylene- Any one of vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-acrylic acid copolymer (EAA), ionomer resin, etc. is suitable for constituting a non-woven fabric. Can be selected. Furthermore, these blend resins may be used, and two or more kinds of each fiber may be blended to form a surface sheet.

  In addition, the cross-sectional shape of the core portion of the conjugate fiber is preferably a round (cylindrical) shape from the viewpoint of spinnability, but is not particularly limited. Moreover, this core part may be hollow.

  Although the composition ratio of the core / sheath in the composite fiber can be arbitrarily determined, in order to ensure the strength of the core that bears the adhesion between the fibers and the bulkiness maintenance, for example, the core / sheath = 80/20 To 20/80, preferably 60/40 to 40/60.

  A general hydrophilic agent can be applied to the composite fiber to impart hydrophilicity to the fiber surface. Moreover, for example, fibers coated with a water repellent oil agent can be blended in order to adjust the hydrophilicity of the nonwoven fabric which is a surface sheet containing the composite fiber.

When using the nonwoven fabric containing a composite fiber as a surface sheet of an absorbent article, for example, the basis weight of the nonwoven fabric is preferably 10 to 50 g / m ² . Further, when considering cost, productivity, texture, cushion feeling, etc., the basis weight of the nonwoven fabric is preferably 20 to 40 g / m ² , for example. If the basis weight is 10 g / m ² or less, the surface strength may not be sufficiently obtained and may break during use. If the basis weight exceeds 50 g / m ² , the liquid is held by the top sheet. This is because the sticky state may be maintained and the user may feel uncomfortable.

Moreover, the density of the fiber in a nonwoven fabric will not be specifically limited if it is 0.12 g / cm < ³ > or less and is liquid-permeable. When the density is greater than 0.12 g / cm ³ , it may be difficult for body fluid or the like to smoothly pass between the composite fibers. For example, when the absorbent article is a sanitary napkin, menstrual blood to be absorbed is more viscous than urine or the like, and therefore it is preferable that the density of the composite fiber in the topsheet is low.

  As the thickness of the composite fiber, for example, a fiber in the range of 1.6 to 11 dtex can be used. And when considering the balance between strength and texture of the nonwoven fabric containing the composite fiber, those in the range of 1.6 to 6.6 dtex are more preferable.

  The content of the composite fiber in the nonwoven fabric that is the topsheet is, for example, preferably 20 to 100% by mass, and more preferably 50 to 100% by mass. When the content rate of the composite fiber in the surface sheet is in the above range, it is preferable because both the concealability and the bulkiness maintaining property in the surface sheet are possible.

  Here, as an index of concealment, for example, a whiteness difference from a standard white plate described later can be exemplified. The surface sheet of the present invention preferably has, for example, a difference in whiteness from a standard white plate of 30 or less, more preferably 25 or less. Moreover, as a parameter | index of bulkiness maintenance property, the bulkiness recovery property mentioned later can be illustrated, for example. In the surface sheet of the present invention, for example, the bulk recovery rate is preferably 50% or more, and more preferably 60% or more. When the top sheet satisfies the above conditions, it is preferable because it is a sheet that achieves both favorable concealability and bulkiness maintenance.

  When the bulkiness maintenance property in a surface sheet is excellent, for example, it is preferable because it is excellent in wearability and rewetting from the absorber can be suppressed. Moreover, when the concealability in a surface sheet is excellent, for example, a clean feeling during use or after use can be provided, which is preferable. That is, a sheet having both bulkiness maintaining property and concealment property can be suitably used as a surface sheet in an absorbent article.

  The composite fiber having the core-sheath structure can be produced by a known method. For example, a core component in which a predetermined amount of an inorganic filler is blended with a resin having a high melting point is supplied to an extruder-type melt spinning machine and melted, and the resin having a low melting point has a higher content than the content of the inorganic filler in the core component; The sheath component containing the inorganic filler is fed to another extruder melt spinning machine and melted. A composite fiber having a core-sheath structure can be produced by spinning each of the melted core component and sheath component from a core-sheath base in which spinnerets are arranged concentrically.

  The method for producing a nonwoven fabric using this conjugate fiber is not particularly limited. Typical methods include spun lace that forms a sheet by entanglement of fiber web, needle punch method, air through method that fixes fiber by adhesive or melting of fiber itself, emboss method, calendar bond method, filament Examples thereof include a spunbond method in which sealing is performed with fibers, and a wet method in which sheets are formed by papermaking.

  Here, when using a nonwoven fabric containing a composite fiber as a surface sheet in an absorbent article, cost (economic efficiency) is required in addition to bulkiness maintenance and softness. preferable.

  Moreover, although the surface sheet in an absorbent article is formed by laminating one or a plurality of non-woven fabrics, it is only necessary that at least one or more non-woven fabrics in the surface sheet contain the above-mentioned composite fiber. And in order to produce the cleanliness of an absorbent article using the concealability in the sheet | seat of this invention, it is preferable that the nonwoven fabric containing the said composite fiber is used for the outermost surface (for example, skin surface side).

[4] Example Below, the evaluation result about the concealability and bulkiness maintenance property in the nonwoven fabric containing the various composite fibers in which the content rate of the titanium dioxide in the core part and the sheath part was adjusted is shown.

In the first to third embodiments, evaluating the nonwoven fabric content with high composite fibers than the content of titanium dioxide (Ti0 ₂₎ contained in the core of the titanium dioxide contained in the sheath (Ti0 _2). In Comparative Example 1 4, to evaluate the nonwoven fabric content using the conventional composite fiber is less than the content of titanium dioxide (Ti0 ₂₎ contained in the core of the titanium dioxide contained in the sheath (Ti0 ₂₎ ing. The manufacturing method and evaluation test method of each nonwoven fabric are as follows.

<Conditions for manufacturing nonwoven fabric>
The nonwoven fabrics in Examples and Comparative Examples were prepared by converting each composite fiber into a web by the card method and adjusting the web to have a basis weight of 30 g / m ² , followed by a blowing temperature of 135 ° C., a passing air speed of about 1 m / sec, and a residence time. It was manufactured by heat bonding with a 30-second mesh conveyor heat treatment machine.

<Nonwoven fabric evaluation test method>
(1) Bulkiness maintenance of the nonwoven fabric (bulk recovery rate)
The non-woven fabric produced as described above is cut into 100 mm × 100 mm and stacked so that the total basis weight is 1000 g / m ² . A weight of 300 g (100 × 100 mm) is placed thereon, and the thickness is measured (initial thickness (mm), initial specific volume (cc / g)).

  Next, a 3500 g (100 × 100 mm) weight is placed instead of the 300 g weight. After leaving in that state for 12 hours, the 3500 g weight is removed. After allowing to stand for 10 minutes, a weight of 300 g is placed and the thickness is measured (recovered thickness (mm), recovery specific volume (cc / g)).

  Then, the bulk recovery rate% (for example, recovery thickness (mm) / initial thickness (mm) × 100) is calculated from the measured result.

(2) Concealability of non-woven fabric (whiteness difference)
The whiteness of the nonwoven fabrics in Examples and Comparative Examples was measured using a color meter (manufactured by Konica Minolta). When the whiteness of a standard white board is measured, it is calibrated so that the measured value is 100, and then, shown in JIS Z8721 “Color Display Method with Three Attributes” in “Standard Color Card 230” manufactured by Nippon Color Research Laboratory. The nonwoven fabrics of Examples 1 to 3 and Comparative Examples 1 to 4 are placed on “4R 3.5 / 11.5 Akane Color” based on the classified color classification, and the whiteness difference ΔE from the standard white board is determined. It was measured. In addition, it was (DELTA) E = 71.5 when the standard color card | curd "Akane color" was directly measured with the color difference meter, without placing a nonwoven fabric. The closer the value of ΔE is to 0, the more white it is.

  Table 1 below shows the composition of the composite fibers constituting the nonwoven fabrics of Examples 1 to 4 and Comparative Examples 1 to 5, and the test evaluation results of the bulk recovery rate and whiteness of each nonwoven fabric.

  From the test evaluation results shown in Table 1, it was found that the nonwoven fabrics of Examples 1 to 4 were excellent in bulk recovery rate and more white in appearance. In other words, it was found that the nonwoven fabrics of Examples 1 to 4 are excellent in bulkiness maintenance and excellent in concealment.

  Although the nonwoven fabrics of Comparative Examples 1 and 4 were excellent in the bulk recovery rate, it was found that it was difficult to feel whiteness in appearance. In other words, when the content of titanium dioxide in the core portion is low and the sheath portion does not contain titanium dioxide, the non-woven fabric may be excellent in bulkiness maintenance, but the concealability may not be ten. all right. Similarly, when the content of titanium dioxide in the core is low and the content of titanium dioxide in the sheath is the same as the content in the core, the bulkiness in the nonwoven fabric is excellent, but concealment It was found that sex might not be enough.

  The non-woven fabrics of Comparative Examples 2, 3 and 5 were more white in appearance, but the bulkiness recovery was not good. In other words, it was found that when the content of titanium dioxide in the core is high and the sheath does not contain titanium dioxide, the non-woven fabric has excellent concealability, but the bulkiness may not be sufficient. . On the contrary, it was found that even when the content of titanium dioxide in the sheath portion is too high, the hiding property in the nonwoven fabric is excellent, but the bulkiness maintenance property may not be sufficient. Moreover, it was found that the nonwoven fabrics of Comparative Examples 3 and 5 had a small initial thickness. That is, it was found that when the content of titanium dioxide in the core part is too high or when the content of titanium dioxide in the sheath part is too high, the initial thickness (bulkyness) of the nonwoven fabric is reduced.

  Further, when Example 1 and Comparative Example 3 having the same total titanium dioxide content were compared, the whiteness on the appearance was the same, but the nonwoven fabric of Example 1 was superior in bulkiness maintenance. Yes. Similarly, when Example 3 and Comparative Example 2 are compared, similarly, the nonwoven fabric of Example 3 is superior in bulkiness maintenance. From this result, even when the content of titanium dioxide in the composite fiber is the same, the nonwoven fabric constituted by the composite fiber having a low content of titanium dioxide in the core and a high content of titanium dioxide in the sheath is more preferable. It was found that the concealability was maintained and the bulkiness was excellent.

It is a top view of the sanitary napkin which is an example of an absorbent article. It is XX 'sectional drawing of the absorbent article in FIG. It is a figure explaining the structure of a composite fiber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sanitary napkin 10 Top sheet 20 Back sheet 30 Absorber 40 Second sheet 50 Leak-proof groove 100 Composite fiber 110 Core part 120 Sheath part 150 Light transmission inhibitor

Claims (9)

An absorbent article comprising at least a part of a liquid-permeable top sheet, a liquid-impermeable back sheet, and an absorbent body disposed between the top sheet and the back sheet,
The surface sheet includes a composite fiber containing a particulate light transmission inhibitor that suppresses light transmission,
The composite fiber has a core part and a sheath part that covers all or a part of the core part and has a melting point lower than that of the core part,
The content rate of the said light transmission inhibitor in the said sheath part is an absorbent article higher than the content rate of the said light transmission inhibitor in the said core part.   The absorptive article according to claim 1 whose content rate of said light transmission inhibitor in said conjugate fiber is 1 mass% or more.   The absorbent article according to claim 1 or 2, wherein a content of the light transmission inhibitor in the core is 4% by mass or less.   The absorptive article according to any one of claims 1 to 3 whose content rate of said light transmission inhibitor in said sheath part is 10 mass% or less. The surface sheet is
The whiteness difference from the standard white board is 30 or less,
The absorbent article according to any one of claims 1 to 4, wherein the bulk recovery rate is 50% or more.   The absorbent article according to claim 1, wherein the light transmission inhibitor is an inorganic filler.   The absorptive article according to any one of claims 1 to 6 whose content rate of said conjugate fiber in said surface sheet is 20-100 mass%. An absorbent article sheet used as a surface sheet in an absorbent article,
The sheet for absorbent articles includes a composite fiber containing a particulate light transmission inhibitor that suppresses transmission of light,
The composite fiber has a core part and a sheath part that covers all or a part of the core part and has a melting point lower than that of the core part,
The content of the light transmission inhibitor in the sheath portion is a sheet for absorbent articles that is higher than the content of the light transmission inhibitor in the core portion. A composite fiber for a surface sheet containing a particulate light transmission inhibitor that suppresses transmission of light used for the surface sheet in the absorbent article,
The composite fiber for a face sheet has a core part and a sheath part that covers all or part of the core part and has a lower melting point than the core part,
The content rate of the said light transmission inhibitor in the said sheath part is a composite fiber for surface sheets higher than the content rate of the said light transmission inhibitor in the said core part.

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