JP6277784B2 - Absorber - Google Patents

Description

  The present invention relates to an absorber for absorbing, for example, body fluids, excreta and the like.

Absorbents using non-woven fabrics are widely used in applications that absorb body fluids, excrement, waste ink, cosmetics, oils, liquid fragrances and repellents; uses that absorb drip from food, etc .; ing.
Such absorbers include not only low-viscosity liquids such as urine, lotion, water, but also high-viscosity liquids and solids such as candy-like foods, creamy cosmetics, loose stools, and mud stools. It is desirable that the contained liquid be sufficiently absorbed.
In addition, the absorbent body for such applications has water decomposability that disperses quickly in water such as flush toilets and biodegradability that is decomposed in water and soil by microorganisms for ease of disposal after use. It is preferable to have.

  Against such a background, for example, in Patent Document 1, as a water-absorbable article used for sanitary products, diapers, etc., it is located on the user's skin side and on the clothing side. A sheet having a back sheet is disclosed. In Patent Document 1, by using a water-decomposable nonwoven fabric having a specific two-layer configuration in which water-dispersible fibers are entangled as a surface sheet, the liquid remaining on the surface sheet can be suppressed and the skin can be given a dry feeling. Is described.

JP 2004-344443 A

  However, although the absorbent article described in Patent Document 1 has the absorbability of a low-viscosity liquid, it is not necessarily suitable for the purpose of penetrating or absorbing a high-viscosity liquid. There was also a tingling sensation when touching the skin. For this reason, it is not suitable for use in applications that may directly absorb skin and absorb high-viscosity objects, such as diapers and sanitary products that absorb body fluids and excreta.

  The present invention has been made in view of the above circumstances, has an excellent texture and feel, and can sufficiently absorb even a liquid containing a high viscosity or a solid, and has water decomposability and biodegradability. The purpose is to provide an absorbent material.

The present invention has the following configuration.
[1] An absorber in which a surface layer is laminated on at least a part of the surface of the absorption layer,
The absorbent layer is made of raw material fibers (Xs) containing 2 to 50% by mass of at least one biodegradable heat-fusible fiber (X) selected from the following fibers (x1) and the following fibers (x2). The airlaid web is heat treated, and the nonwoven fabric (α) having an apparent density of 0.015 to 0.045 g / cm ³ ,
The surface layer comprises a raw fiber (Ys) containing a biodegradable polyester fiber (Y1) and a cellulose fiber (Y2) having a fiber length of 20 to 100 mm, and a water-soluble resin (Y3) represented by the following formula (1) and It contains so that the mass ratio represented by (2) may be satisfy | filled, It consists of a nonwoven fabric ((beta)) whose apparent density is 0.005-0.045 g / cm < ³ >, and a basic weight is 10-100 g / m < ² >. Absorber.
Fiber (x1): polybutylene succinate, poly (hydroxybutyrate / hydroxyhexanoate), polycaprolactone, poly (caprolactone / butylene succinate), poly (butylene succinate / adipate), poly (butylene succinate / carbonate) ), Poly (butylene adipate / terephthalate) and at least one resin (A) selected from polyethylene succinate, a biodegradable heat-fusible fiber.
Fiber (x2): at least one resin (B) selected from polylactic acid, polyhydroxybutyrate, polyglycolic acid and cellulose acetate, and the resin (A), and at least a part of the surface of the resin (B) A) biodegradable heat-fusible fiber.
0.75 ≦ Y1 / Y2 ≦ 30 (1)
0.002 ≦ Y3 / (Y1 + Y2) ≦ 0.3 (2)

[2] The absorbent body according to [1], wherein the biodegradable polyester fiber (Y1) is a latent crimped fiber.
[3] The absorbent material according to [1] or [2], wherein the raw fiber (Ys) is chemically bonded with the water-soluble resin (Y3).
[4] The absorbent according to any one of [1] to [3], wherein the cellulose fiber (Y2) has a fiber length of 20 to 100 mm.
[5] The absorbent body according to any one of [1] to [4], wherein the water-soluble resin (Y3) is polyvinyl alcohol.
[6] The absorbent body according to any one of [1] to [5], wherein the nonwoven fabric (α) has a basis weight of 50 to 1200 g / m ² .
[7] It further has a water absorption layer made of a nonwoven fabric (β) formed from raw fiber (Zs) containing 5 to 98% by mass of cellulose fiber, and the absorption layer is between the water absorption layer and the surface layer. It is located, The absorber in any one of [1]-[6] characterized by the above-mentioned.
[8] The non-woven fabric (alpha) is the apparent density of 0.016~0.020g / cm ³ of apparent density of the nonwoven fabric (beta) is 0.005~0.04g / cm ³ [1] ~ [7] The absorber according to any one of [7].
[9] The absorber according to any one of [1] to [8], wherein the thickness of the absorption layer is 5 to 40 mm, and the thickness of the surface layer is 1.0 to 5 mm.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is the liquid which is excellent in a texture and the touch, and contains a highly viscous liquid and solid content, it can provide an absorber provided with water decomposability and biodegradability.

It is a longitudinal cross-sectional view which shows the layer structure of the absorber of 1st Embodiment. It is a longitudinal cross-sectional view which shows the layer structure of the absorber of 2nd Embodiment. It is a longitudinal cross-sectional view which shows the layer structure of the absorber of 3rd Embodiment.

Hereinafter, the present invention will be described in detail with reference to exemplary embodiments.
(1) 1st Embodiment FIG. 1: is a longitudinal cross-sectional view which shows the structure of 10 A of absorbers of the 1st Embodiment of this invention.
The absorbent body 10 </ b> A in this example has a two-layer configuration in which the surface layer 11 is laminated on the entire surface of one surface of the absorption layer 12. In the absorbent body 10A, for example, absorption objects such as body fluids, excrement, waste ink, cosmetics, oil, liquid fragrance and repellent are absorbed from the surface layer 11 side. Therefore, when the absorbent body 10A is attached to a human body or the like as a diaper or sanitary product, the surface layer 11 comes into contact with the skin.

<Absorbent layer (nonwoven fabric α)>
The absorption layer 12 is a layer that absorbs and holds an object to be absorbed, and is made of a nonwoven fabric (α) that has water decomposability and biodegradability.
As will be described in detail later, the nonwoven fabric (α) is a nonwoven fabric obtained from an airlaid web by adopting the airlaid method as a web forming step, and is bulky and has a low density. The airlaid web forming the nonwoven fabric (α) contains 2 to 50% by mass of at least one biodegradable heat-fusible fiber (X) selected from the following fibers (x1) and the following fibers (x2). It is formed from raw fiber (Xs). And since a nonwoven fabric ((alpha)) is a nonwoven fabric by which the thermal bond method (heat processing) was employ | adopted as a fiber bonding process, raw material fibers (Xs) are adhere | attached mainly by the point.
Therefore, the nonwoven fabric (α) is excellent in the permeability of a high-viscosity liquid and a liquid containing solids (hereinafter also referred to as “high-viscosity absorption object”), and effectively absorbs the high-viscosity absorption object. Can hold. The non-woven fabric (α) is formed from the raw fiber (Xs) containing the biodegradable heat-fusible fiber (X) in the above range, and an appropriate amount of the biodegradable heat-fusible fiber. Since the bonding force does not become excessive based on the above point adhesion by (X), it also has water decomposability.

Fiber (x1): polybutylene succinate, poly (hydroxybutyrate / hydroxyhexanoate), polycaprolactone, poly (caprolactone / butylene succinate), poly (butylene succinate / adipate), poly (butylene succinate / carbonate) ), At least one resin (A) selected from poly (butylene adipate / terephthalate) and polyethylene succinate.
Fiber (x2): at least one resin (B) selected from polylactic acid, polyhydroxybutyrate, polyglycolic acid and cellulose acetate, and the resin (A), and at least a part of the surface of the resin (B) A) biodegradable heat-fusible fiber.

  In the illustrated example, the absorbent layer 12 is composed of a single nonwoven fabric (α). However, depending on the quality and quantity of the object to be absorbed, two or more nonwoven fabrics (α) are stacked to form the absorbent layer. It may be formed.

[Resin (A) and Resin (B)]
As described above, the resin (A) includes polybutylene succinate (melting point: 114 ° C.), poly (hydroxybutyrate / hydroxyhexanoate) (melting point: 100 to 110 ° C.), polycaprolactone, poly (caprolactone / butylene succin). Nate) (melting point: 104 ° C.), poly (butylene succinate / adipate) (melting point: 95 ° C.), poly (butylene succinate / carbonate) (melting point: 106 ° C.), poly (butylene adipate / terephthalate) and polyethylene succinate (Melting point: 119 ° C.).
Resin (A) is excellent in biodegradability and has a low melting point. Since the resin (A) has a low melting point, the raw fiber (Xs) containing the biodegradable heat-fusible fiber (X) containing the resin (A) is used to form an airlaid web and heat-treat. At least a part of (A) is melted and the raw fibers (Xs) are fused. That is, the resin (A) functions as a binder component and contributes to improving the shape retention of the nonwoven fabric (α).
In addition, since the resin (A) has a melting point in the range of 90 to 120 ° C. and the melting point is not too low, it is easy to control the temperature at the time of heat-sealing and can prevent the adhesive strength from becoming too large. . In addition, since the melting point is not too high, the thermal energy at the time of thermal fusion can be suppressed, which is advantageous in terms of cost. Furthermore, since the temperature of the heat treatment does not need to be excessively high, softening and thermal deformation of portions other than the heat-fusible resin component in the raw fiber (Xs) can be prevented, and a sheet having a stable form can be formed.

As described above, the resin (B) is selected from polylactic acid (melting point: 175 ° C.), polyhydroxybutyrate (melting point: 175 ° C.), polyglycolic acid (melting point: 230 ° C.) and cellulose acetate (melting point: 230 ° C.). At least one kind.
Resin (B) is excellent in biodegradability and has a higher melting point than resin (A), and is in the range of 170 ° C. or higher. Therefore, the resin (B) is included together with the resin (A), and at least one of the fibers (x2) in which the resin (A) is present on at least a part of the surface is used as the biodegradable heat-fusible fiber (X). When the air-laid web is formed from the raw material fibers (Xs) containing this and heat-treated, the resin (A) in the fibers (x2) functions as a binder component and contributes to improving the shape retention of the nonwoven fabric (α). On the other hand, the resin (B) does not melt and contributes to the maintenance of the fiber form.
If the melting point of the resin (B) is 170 ° C. or higher, it is possible to prevent deformation of the web due to softening or thermal deformation of a portion constituted by the resin (B) in the fiber (x2) during heat treatment.

  In the present specification, the melting point of the resin is a value measured by a trace melting point measurement method using a DSC (scanning calorimeter) or the like.

[Raw fiber (Xs)]
Raw material fiber (Xs) contains 2-50 mass% of at least 1 sort (s) of biodegradable heat-fusible fiber (X) chosen from fiber (x1) and fiber (x2). Moreover, raw material fiber (Xs) contains 50-98 mass% of non-heat-fusible fiber mentioned later in detail.

(Biodegradable heat-fusible fiber (X))
The fiber (x1) used as the biodegradable heat-fusible fiber (X) is not particularly limited as long as it is made of the above-described resin (A). You may use what was manufactured.

1 or more types of resin (A) which comprises fiber (x1) are used, and when it is 2 or more types, even if fiber (x1) is a mixture of 2 or more types of fibers, 2 or more types of resins ( A composite fiber obtained by combining A) may be used.
Examples of the fiber form of the composite fiber include a side-by-side structure and a core-sheath structure obtained by combining two different types of resins (A). The core-sheath structure may be a concentric core-sheath structure or an eccentric core-sheath structure.
Moreover, even if it is the same kind, the mixture and composite fiber of 2 or more types of resin from which molecular weight differs may be sufficient.

The fiber (x2) used as the biodegradable heat-fusible fiber (X) is composed of the above resin (B) and the above resin (A), and at least a part of the surface of the fiber is a resin (A If it consists of), it will not specifically limit, Even if it uses a commercial item, what was manufactured by the well-known method may be used.
Examples of the fiber form in which at least a part of the surface is the resin (A) include a side-by-side type structure and a core-sheath type structure obtained by combining the resin (A) and the resin (B). In the case of the core-sheath structure, the resin (A) constitutes the sheath part, and the resin (B) constitutes the core part. The core-sheath structure may be a concentric core-sheath structure or an eccentric core-sheath structure.
One or more of the resin (A) and the resin (B) constituting the fiber (x2) are used.

  The mass ratio of the resin (A) to the resin (B) in the fiber (x2) (for example, the core-sheath composite ratio in the core-sheath structure) is resin (A) / resin (B) = 2/8 to 8 /. 2 is preferable, and 4/6 to 6/4 is more preferable. If mass ratio is in the said range, both the function as a binder component of resin (A) and the function which maintains the fiber form of resin (B) will be excellent.

The fiber (x2) may be a latent crimped fiber.
A latent crimp fiber is a fiber in which crimp (crimp, curl, spiral) is manifested by heat. When the air-laid web formed including the latent crimped fibers is heat-treated, the crimps become obvious. Therefore, the obtained nonwoven fabric (α) becomes more bulky.
Examples of the fiber form of the latent crimped fiber used as the fiber (x2) include a side-by-side structure obtained by combining the resin (A) and the resin (B), and a synthetic fiber having an eccentric core-sheath structure. Can be mentioned.
The latent crimped fiber may or may not have a moderate crimp in advance.

2-20 mm is preferable, as for the fiber length of a fiber (x1) and a fiber (x2), 2-10 mm is more preferable, and 2-6 mm is further more preferable. With such a fiber length, these fibers are randomly stacked three-dimensionally when forming an airlaid web. As a result, it is easy to obtain a non-woven fabric (α) that is bulky and exhibits excellent permeability even for a high-viscosity absorption object, and can sufficiently absorb and retain the high-viscosity absorption object. Moreover, it becomes difficult for the obtained nonwoven fabric ((alpha)) to lose shape, such as thickness reduction by the weight of a high viscosity absorption target object. If the fiber length is less than the lower limit of the above range, the fibers are too dense, and there is a concern that the permeability of the resulting non-woven fabric (α) may be reduced, the texture may be hard, or the tingling sensation may occur. If the fiber length exceeds the upper limit of the above range, the fiber lies and it becomes difficult to laminate three-dimensionally.
Since the absorbent body 10A provided with the nonwoven fabric (α) having excellent permeability as the absorbent layer 12 absorbs the high-viscosity absorption object quickly and does not remain on the surface layer 11, the diffusion area of the high-viscosity absorption object Can be reduced.

  The fineness of the fiber (x1) and the fiber (x2) is preferably 0.5 to 74 dtex, more preferably 0.8 to 35 dtex, and still more preferably 1.0 to 20 dtex. With such fineness, the nonwoven fabric (α) that is bulky and exhibits excellent permeability even to a high-viscosity absorption object and sufficiently absorbs and holds the high-viscosity absorption object is easily obtained. Moreover, the nonwoven fabric (α) is excellent in texture. When the fineness is less than the lower limit of the above range, the texture is good, but the size of the gap between the fibers is small, the resistance when absorbing the high-viscosity absorbent object is increased, and the permeability tends to be inferior. There is. If the fineness exceeds the upper limit of the above range, the fiber itself becomes stiff, and the tingling feeling increases and the texture tends to deteriorate.

In the present specification, the fiber length is an average value of lengths measured by observation with an electron microscope using 50 arbitrarily selected fibers as samples.
The fineness is expressed in the unit “dtex (decitex)”. 1 dtex is the thickness of a thread having a length of 10,000 m and a weight of 1 g.

As the biodegradable heat-fusible fiber (X), only the fiber (x1) may be used, or only the fiber (x2) may be used, or these may be used in combination. Two or more types of fibers (x1) may be used in combination, or two or more types of fibers (x2) may be used in combination.
Especially, it is preferable to use a fiber (x2) at least as biodegradable heat-fusible fiber (X). The fiber (x2) has a melting point higher than that of the resin (A) and has a resin (B) that does not melt at the heat treatment temperature when the air-laid web is heat-treated. Therefore, at least the fiber (x2) is used as the biodegradable heat-fusible fiber (X), and the higher the use ratio is, the higher the bulk and the better the permeability to the high viscosity object. In addition, it is easy to obtain a non-woven fabric (α) that absorbs and holds a highly viscous object to be absorbed more sufficiently.
In addition, as described above, when latent crimped fibers are used as the fibers (x2), the nonwoven fabric (α) that is more bulky and suitable for absorbing and holding a high-viscosity object is easily obtained.

  Content of the biodegradable heat-fusible fiber (X) in raw material fiber (Xs) is 2-50 mass%. When the content of the biodegradable heat-fusible fiber (X) is not less than the lower limit of the above range, the binding point between the fibers is sufficiently present, so that the shape retention of the nonwoven fabric (α) becomes good, Excellent permeability is exhibited even for high viscosity objects. Moreover, it is hard to lose shape and is excellent in biodegradation. On the other hand, when the amount is not more than the upper limit of the above range, it is easy to obtain a nonwoven fabric (α) that is bulky, has excellent permeability to a high-viscosity absorption object, and has good water decomposability.

  However, when the content of the biodegradable heat-fusible fiber (X) in the raw fiber (Xs) is 10% by mass or more, polyvinyl alcohol (PVA) fiber is used as the non-heat-fusible fiber described later. It is preferable to use at least. Thereby, the water disintegration property of a nonwoven fabric ((alpha)) is more excellent. That is, when raw material fiber (Xs) does not contain PVA fiber as non-heat-fusible fiber, the content of biodegradable heat-fusible fiber (X) in raw material fiber (Xs) is 2 mass. % To less than 10% by mass is more preferable, and 5 to 8% by mass is particularly preferable.

(Non-heat fusible fiber)
Raw material fiber (Xs) contains a non-heat-bondable fiber in the range of 50 to 98% by mass.
The non-heat-bondable fiber is a fiber made of a resin that does not melt during heat treatment of the air laid web, and is made of the above-mentioned resin (B) (hereinafter also simply referred to as “high-melting fiber”); PVA fiber; And any fiber other than fibers and PVA fibers. The non-heat-fusible fiber preferably contains a high melting point fiber from the viewpoint of biodegradability of the nonwoven fabric (α), and preferably contains a PVA fiber from the viewpoint of water decomposability. Therefore, from the viewpoint of both biodegradability and water decomposability, it is preferable to use high melting point fibers and PVA fibers as non-heat-fusible fibers.

The high melting point fiber is not particularly limited as long as it is composed of one or more kinds of the resin (B), and a commercially available product or a product produced by a known method may be used.
When the resin (B) constituting the high melting point fiber is two or more kinds, the high melting point fiber is a composite fiber obtained by compounding two or more kinds of resins (B) even if it is a mixture of two or more kinds of fibers. There may be.
Examples of the fiber form of the composite fiber include a side-by-side structure and a core-sheath structure obtained by combining two different types of resins (B). The core-sheath structure may be a concentric core-sheath structure or an eccentric core-sheath structure.
Moreover, even if it is the same kind, the mixture and composite fiber of 2 or more types of resin from which molecular weight differs may be sufficient.
One or more high melting point fibers can be used.

The high melting point fiber may be solid or hollow, and may be a latent crimped fiber or a fiber that does not have crimpability. Preferably, hollow latent crimp fibers are particularly preferred.
Since the latent crimped fiber is manifested by heat, the crimp is manifested when the airlaid web formed including the latent crimped fiber is heat-treated. Therefore, the obtained nonwoven fabric (α) becomes more bulky.
Furthermore, when the latent crimped fiber is a hollow latent crimped fiber having a hollow portion along the axial direction, the hollow portion can reduce the basis weight of the nonwoven fabric (α) and cushion the nonwoven fabric (α). Sex can be imparted. As a result, the rigidity of the absorber 10A can be reduced, and the usability of the absorber 10A is excellent.

  Examples of the hollow latent crimped fiber used as the high melting point fiber include a hollow composite fiber imparted with latent crimp by arranging resins (B) having different heat shrinkability in a side-by-side type, for example. Among these, hollow latent crimped fibers in which polylactic acids having different molecular weights are arranged in a side-by-side manner are preferable.

  The fiber length of the high melting point fiber is preferably 2 to 20 mm, more preferably 2 to 10 mm, and further preferably 2 to 6 mm for the same reason as the biodegradable heat-fusible fiber (X) described above.

  The fineness of the high melting point fiber is preferably 0.5 to 74 dtex, more preferably 0.8 to 35 dtex, and further preferably 1.0 to 20 dtex, for the same reason as the biodegradable heat-fusible fiber (X) described above. preferable. However, in the case of hollow latent crimped fibers, the fineness is preferably 5 to 50 dtex, more preferably 8 to 35 dtex, and still more preferably 10 to 25 dtex.

The PVA fiber is a water-soluble fiber, and a commercially available product or a product produced by a known method may be used.
As PVA resin which comprises PVA fiber, what satisfy | fills JIS standard K6950 (ISO14885) of a biodegradable plastic is desirable.
The fiber length of the PVA fiber is preferably 2 to 20 mm, more preferably 2 to 10 mm, and even more preferably 2 to 6 mm for the same reason as the biodegradable heat-fusible fiber (X).
For the same reason as the biodegradable heat-fusible fiber (X), the fineness of the PVA fiber is preferably 0.5 to 74 dtex, more preferably 0.8 to 35 dtex, and still more preferably 1.0 to 20 dtex.

  As an arbitrary fiber that does not correspond to the high melting point fiber or the PVA fiber, a fiber that does not impair the biodegradability of the nonwoven fabric (α) can be used. Specific examples include cellulose fibers (pulp, rayon, cupra, cotton, etc.), natural fibers, and the like. However, since the cellulose fiber is hydrophilic, if the content in the raw material fiber (Xs) is too large, the permeability of the absorbent layer may be impaired. Therefore, the content of the cellulose fiber in the raw fiber (Xs) is preferably less than 5% by mass, more preferably 3% by mass or less, and particularly preferably 2% by mass or less.

(Suitable structure of raw fiber (Xs))
The raw fiber (Xs) is composed of a biodegradable heat-fusible fiber (X) and a non-heat-fusible fiber, and the non-heat-fusible fiber has a biodegradability of the nonwoven fabric (α) as described above. From the viewpoint of both water decomposability, it is preferable to include a high melting point fiber and a PVA fiber. The high melting point fiber preferably includes at least a hollow latent crimped fiber, and more preferably, only the hollow latent crimped fiber is used as the high melting point fiber.

Content of the biodegradable heat-fusible fiber (X) in raw material fiber (Xs) is 2-50 mass%, 3-30 mass% is preferable and 5-20 mass% is more preferable.
10-98 mass% is preferable, as for content of the high melting point fiber in raw material fiber (Xs), 20-95 mass% is more preferable, and 50-90 mass% is further more preferable.
0-98 mass% is preferable, as for content of the PVA fiber in raw material fiber (Xs), 3-50 mass% is more preferable, and 10-30 mass% is further more preferable.
When the contents of the biodegradable heat-fusible fiber (X), the high melting point fiber, and the PVA fiber in the raw material fiber (Xs) are within the above ranges, the nonwoven fabric (α) is bulky, low in density, and high It has exceptionally excellent permeability to viscosity-absorbing objects, and is extremely excellent in water decomposability and biodegradability.

  As a ratio of the biodegradable heat-fusible fiber (X) and the PVA fiber, from the viewpoint of water decomposability, the content of the PVA fiber is 100% by mass of the content of the biodegradable heat-fusible fiber (X). When it is, it is preferable that it is 50 mass% or more, and it is more preferable that it is 100-200 mass%.

[Ingredients other than raw fiber (Xs)]
The absorbent layer 12 made of the nonwoven fabric (α) may contain other components other than the raw fiber (Xs) as necessary within the range not impairing the effects of the present invention.
As the other components, known functional additives used in articles that absorb liquids and the like can be used.
Specifically, for example, zeolite, activated carbon, chitin, chitosan, scallop shell, titanium oxide, titanium dioxide, magnesium oxide, plant extract, mushroom extract, catechin, flavonol, cyclodextrin, collagen fiber, iron oxide, citric acid, Examples thereof include an additive having any one or more of a deodorizing function, an antibacterial function, an antiviral function, an antiallergen function, an antifungal function, an aroma function, and the like, such as zinc pyrithione, hinokitiol, and eucalyptus extract.
These additives can be applied by a method suitable for each additive, for example, a method of mixing the raw fiber (Xs) when forming an airlaid web by the airlaid method.

[Apparent density, basis weight, thickness]
Nonwoven fabric constituting the absorption layer (alpha) has an apparent density of 0.015~0.045g / cm ^3, it is preferable that 0.016~0.020g / cm ^3. When the apparent density exceeds the upper limit of the above range, there are few voids in the non-woven fabric (α) or the size of the voids is small, so that the permeability to the object with high viscosity absorption becomes insufficient and high viscosity absorption It becomes difficult to sufficiently absorb and hold the object. Moreover, the usability of the absorbent body 10A is also reduced. If the apparent density is less than the lower limit of the above range, there are many voids in the nonwoven fabric (α) or the size of the voids is large. Is significantly reduced. Moreover, even if a high-viscosity absorption target object is once absorbed, it is hard to hold | maintain and there exists a possibility that the high-viscosity absorption target object may reverse.

  When the absorbent layer is a laminate of two or more nonwoven fabrics (α), the apparent density of each nonwoven fabric (α) may be the same as or different from each other as long as it is within the above range.

Although there is no limitation on the basis weight of the absorbent layer 12 is preferably 50~1200g / ^{m 2,} more preferably from 60~1000g / ^{m 2,} more preferably from 80~800g / ^{m 2} 80 to 120 g / m ² is particularly preferable. When the basis weight is less than or equal to the upper limit of the above range, the absorbent body 10A is excellent in handleability and wearing feeling when the absorbent body 10A is worn as a diaper, sanitary article, etc., and the absorbent body 10A is also excellent in productivity. . When the basis weight is equal to or higher than the lower limit of the above range, the high viscosity object to be absorbed can be sufficiently absorbed and retained.

  When the absorbent layer is a laminate of two or more nonwoven fabrics (α), the basis weight of the absorbent layer is the total basis weight of the two or more nonwoven fabrics (α). The basis weight of each nonwoven fabric (α) may be the same as or different from each other as long as the total basis weight of two or more nonwoven fabrics (α) is within the above range.

  Although there is no restriction | limiting in the thickness of the absorption layer 12, It is preferable that it is 3-40 mm, It is more preferable that it is 4-30 mm, It is further more preferable that it is 5-20 mm, 5-7 mm is especially preferable. When the thickness is not more than the upper limit of the above range, the handleability and wearing feeling when the absorbent body 10A is worn on a human body or the like as a diaper, sanitary product, etc. are excellent. When the thickness is not less than the lower limit of the above range, the high-viscosity absorption object can be sufficiently absorbed and retained.

  When the absorbent layer is a laminate of two or more nonwoven fabrics (α), the thickness of the absorbent layer is the total thickness of the two or more nonwoven fabrics (α). The thickness of each nonwoven fabric (α) may be the same as or different from each other as long as the thickness of the absorbent layer is within the above range.

<Surface layer (nonwoven fabric β)>
The surface layer 11 is a layer laminated on at least a part of the surface of the absorption layer 12. In the example of FIG. 1, the surface layer 11 has a configuration in which it is laminated on the entire surface of one surface of the absorption layer 12. In the absorbent body 10A, the object to be absorbed is absorbed from the surface layer 11 side.

The surface layer 11 is provided in order to improve the texture, touch, strength, and the like of the surface of the absorbent body 10A. Further, the surface layer 11 also has an effect of preventing the fibers from falling off the absorbent layer 12. That is, the above-mentioned absorption layer 12 may be easily dropped from the raw fibers (Xs) due to the nonwoven fabric (α) obtained by heat-treating the air laid web. On the other hand, by providing the surface layer 11 on the surface of the absorption layer 12, it is possible to prevent the raw fibers (Xs) from falling off from the nonwoven fabric (α).
An object such as a high-viscosity absorption object is absorbed and held by the absorption layer 12. Therefore, the surface layer 11 needs to allow the object to pass through quickly.

The nonwoven fabric (β) contains raw fiber (Ys) containing biodegradable polyester fiber (Y1) and cellulose fiber (Y2), and water-soluble resin (Y3), and has an apparent density of 0.005 to 0.00. It is a nonwoven fabric of 045 g / cm ³ and a basis weight of 10 to 100 g / m ² .

[Raw fiber (Ys)]
Examples of the biodegradable polyester fiber (Y1) include polybutylene succinate, poly (hydroxybutyrate / hydroxyhexanoate), polycaprolactone, poly (caprolactone / butylene succinate), and poly (butylene succinate / adipate). And fibers made of biodegradable polyesters such as poly (butylene succinate / carbonate), poly (butylene adipate / terephthalate), polyethylene succinate, polylactic acid, polyhydroxybutyrate and polyglycolic acid.

The biodegradable polyester fiber (Y1) is a fiber composed of one or more kinds of biodegradable polyester. When the biodegradable polyester fiber (Y1) is composed of two or more kinds of biodegradable polyester, the biodegradable polyester fiber (Y1) is composed of two or more kinds. It may be a mixture of biodegradable polyester fibers or a composite fiber in which two or more biodegradable polyesters are combined.
Examples of the fiber form of the composite fiber include a side-by-side structure and a core-sheath structure obtained by combining two different types of biodegradable polyesters. The core-sheath structure may be a concentric core-sheath structure or an eccentric core-sheath structure.
Moreover, even if it is the same kind, the mixture and composite fiber of 2 or more types of resin from which molecular weight differs may be sufficient.
One or more biodegradable polyester fibers (Y1) can be used.

The biodegradable polyester fiber (Y1) may be solid or hollow, and may be a latent crimped fiber or a fiber that does not have crimpability. Latent crimped fibers are preferred, and hollow latent crimped fibers are particularly preferred.
Since the crimps of the latent crimped fibers are manifested by heat, the crimps are manifested by applying heat in the drying process of the nonwoven fabric (β) as will be described in detail later. Therefore, the obtained non-woven fabric (β) becomes more bulky and excellent in texture and touch, and can be permeated well without leaving a high viscosity absorbent object on the surface.
Furthermore, the basic weight of a nonwoven fabric ((beta)) can be reduced as a latent crimped fiber is a hollow latent crimped fiber which has the hollow part which follows an axial direction.
The latent crimped fiber is preferably a biodegradable polyester resin having different heat shrinkability, for example, a hollow composite fiber arranged in a side-by-side type, and in particular, a hollow fiber in which polylactic acids having different molecular weights are arranged in a side-by-side type. preferable.

  The fiber length of the biodegradable polyester fiber (Y1) is 20 to 100 mm, preferably 30 to 90 mm, and more preferably 50 to 80 mm. When the fiber length is not less than the lower limit of the above range, the ends of the biodegradable polyester fiber (Y1) present per unit area of the nonwoven fabric (β) are reduced, and the surface of the nonwoven fabric (β) becomes smooth. Therefore, the nonwoven fabric (β) which is excellent in texture and touch and suitable for forming the surface layer 11 is obtained. When the fiber length of the biodegradable polyester fiber (Y1) is less than or equal to the upper limit of the above range, the unwoven cloth can be easily formed, and an unwoven cloth (β) having a uniform texture and excellent texture can be obtained. .

  The fineness of the biodegradable polyester fiber (Y1) is preferably 0.5 to 74 dtex, more preferably 0.8 to 35 dtex, and still more preferably 1.0 to 20 dtex. However, in the case of hollow latent crimped fibers, the fineness is preferably 5 to 50 dtex, more preferably 8 to 35 dtex, and still more preferably 10 to 25 dtex. When the fineness is less than the lower limit of the above range, the touch is good, but the size of the gap between the fibers is reduced, the permeability of the high-viscosity absorption object is reduced, and the high-viscosity absorption object is present on the surface layer 11. It may remain. If the fineness exceeds the upper limit of the above range, the fiber itself becomes stiff and the tingling sensation increases and the touch tends to deteriorate.

Cellulose fiber (Y2) is used to increase the hydrophilicity of the entire raw fiber (Ys). As the hydrophilicity of the raw fiber (Ys) increases, as will be described in detail later, the water-soluble resin (Y3) used as a binder component is sufficiently adhered to the raw fiber (Ys), and the raw fiber (Ys) is bonded to each other. It can be fully bonded. As a result, a nonwoven fabric (β) having excellent strength can be obtained.
Examples of the cellulose fibers (Y2) include pulp fibers, rayon fibers (including rayon derivative fibers such as acetate rayon fibers), cotton fibers, and cupra fibers. In addition, rayon fibers are preferred because of the high diversity of fiber designs.
One or more types of cellulose fibers (Y2) can be used.

  Since the cellulose fiber (Y2) is softer than the biodegradable polyester fiber (Y1) described above, the surface smoothness of the nonwoven fabric (β) is hardly affected even if the fiber length is short, but the biodegradable polyester It is preferable that it is 20-100 mm like a fiber (Y1). Furthermore, 30-90 mm is preferable and 40-80 mm is more preferable.

  The fineness of the cellulose fiber (Y2) is preferably 0.5 to 74 dtex, more preferably 1.5 to 50 dtex, and further preferably 2 to 30 dtex. When the fineness is less than the lower limit of the above range, the touch is good, but the size of the gap between the fibers is reduced, the permeability of the high-viscosity absorption object is reduced, and the high-viscosity absorption object is present on the surface layer 11. It may remain. When the fineness exceeds the upper limit of the above range, the touch may be deteriorated.

  The raw fiber (Ys) may include any fiber that does not correspond to the biodegradable polyester fiber (Y1) and the cellulose fiber (Ys). Optional fibers include natural fibers other than cellulose fibers. The content of any fiber in the raw fiber (Ys) is preferably 30% by mass or less.

[Water-soluble resin (Y3)]
As described above, the water-soluble resin (Y3) is used as a binder component that binds the raw fibers (Ys). Although mentioned later in detail, in the manufacturing process of a nonwoven fabric ((beta)), raw material fibers (Ys) can be couple | bonded by providing the aqueous solution of water-soluble resin (Y3), and drying. By using the water-soluble resin (Y3) as a binder component, the water disintegration of the nonwoven fabric (β) is excellent.

  Examples of the water-soluble resin (Y3) include PVA, starch, starch derivatives, sodium alginate, gum tart, guar gum, xanthan gum, gum arabic, carrageenan, galactomannan, gelatin, casein, albumin, pull plan, polyethylene oxide, PVA, bis Course, polyvinyl ethyl ether, poly (sodium acrylate), poly (sodium methacrylate), polyacrylamide, hydroxylated derivative of poly (acrylic acid), polyvinyl pyrrolidone / vinyl pyrrolidone vinyl acetate copolymer, carboxyethyl cellulose, salt of carboxyethyl cellulose, carboxymethyl cellulose, carboxy A salt of methyl cellulose can be used, and one or more can be used, but PVA is preferable from the viewpoint of excellent adhesion performance and water decomposability.

[Content and ratio of each component]
In the nonwoven fabric (β), the biodegradable polyester fiber (Y1) and cellulose fiber (Y2) constituting the raw fiber (Ys) and the water-soluble resin (Y3) are represented by the following formulas (1) and (2). Satisfy the expressed mass ratio.
0.75 ≦ Y1 / Y2 ≦ 30 (1)
0.002 ≦ Y3 / (Y1 + Y2) ≦ 0.3 (2)

In addition, the symbol in Formula (1) and (2) means the following.
Y1: Mass of biodegradable polyester fiber (Y1) in nonwoven fabric (β) Y2: Mass of cellulose fiber (Y2) in nonwoven fabric (β) Y3: Mass of water-soluble resin (Y3) in nonwoven fabric (β)

  When the mass ratio (Y1 / Y2) satisfies the above formula (1), the ratio of the biodegradable polyester fiber (Y1) and the cellulose fiber (Y2) is appropriate, so that the strength, water disintegration, texture and the like are excellent. A nonwoven fabric (β) is obtained. Specifically, if the mass ratio (Y1 / Y2) is less than the lower limit of the above range, most of the water-soluble resin (Y3) used as the binder component will adhere to the cellulose fibers (Y2), As a result, water disintegration is reduced. Moreover, it is easy to produce the feeling fall (feeling of a sense of harshness) by drying of a binder component. On the other hand, when the mass ratio (Y1 / Y2) exceeds the upper limit of the above range, the amount of the cellulose fiber (Y2) is too small, and thus the hydrophilicity of the entire raw fiber (Ys) becomes insufficient. As a result, as will be described in detail later, the water-soluble resin (Y3) used as the binder component is not sufficiently adhered to the raw fiber (Ys), and the strength of the nonwoven fabric (β) is insufficient.

  If the mass ratio (Y3 / (Y1 + Y2)) is less than the lower limit represented by the above formula (2), the amount of the water-soluble resin (Y3) is too small, and the raw fibers (Ys) can be sufficiently bonded. However, the strength of the nonwoven fabric (β) is insufficient. If the mass ratio (Y3 / (Y1 + Y2)) exceeds the upper limit indicated by the above formula (3), the amount of the water-soluble resin (Y3) is too large, and the nonwoven fabric (β) has an irritating feeling, and the texture and touch are descend. In addition, the water-soluble resin (Y3) may block the voids of the nonwoven fabric (β), impede the permeation of the object, and the high-viscosity absorption object may diffuse greatly on the surface layer.

The mass ratio (Y1 / Y2) preferably satisfies the following formula (3), and the mass ratio (Y3 / (Y1 + Y2)) preferably satisfies the following formula (4).
0.8 ≦ Y1 / Y2 ≦ 9 (3)
0.025 ≦ Y3 / (Y1 + Y2) ≦ 0.3 (4)

[Ingredients other than raw fiber (Ys) and water-soluble resin (Y3)]
The surface layer 11 made of the non-woven fabric (β) may contain other components other than the raw fiber (Ys) and the water-soluble resin (Y3) as necessary, as long as the effects of the present invention are not impaired.
As the other components, the known functional additives described above can be used.

[Apparent density, basis weight, thickness]
The apparent density of the nonwoven fabric (β) constituting the surface layer 11 is 0.005 to 0.045 g / cm ³ , and preferably 0.005 to 0.04 g / cm ³ . When the apparent density exceeds the upper limit of the above range, the high-viscosity absorption object cannot quickly pass through the surface layer made of nonwoven fabric (β), and the surface layer prevents the absorption and retention of the high-viscosity absorption object by the absorption layer. End up. As a result, the high-viscosity absorption object diffuses greatly on the surface layer. Moreover, the water decomposability of the nonwoven fabric (β) is also reduced. If the apparent density is less than the lower limit of the above range, the unwoven cloth (β) may be crushed depending on the weight of the high-viscosity object to be absorbed, and the absorbability and retention as a sheet cannot be maintained.

The nonwoven fabric (β) constituting the surface layer 11 has a basis weight of 10 to 100 g / m ² and preferably 15 to 60 g / m ² . When the basis weight exceeds the upper limit of the above range, the high-viscosity absorption object cannot quickly pass through the surface layer made of the nonwoven fabric (β), and the surface layer prevents the absorption and retention of the high-viscosity absorption object by the absorption layer. End up. As a result, the high-viscosity absorption object diffuses greatly on the surface layer. Moreover, the water decomposability of the nonwoven fabric (β) is also reduced. If the basis weight is less than the lower limit of the above range, the effect of providing the nonwoven fabric (β) cannot be expected because the layer does not function as an absorber.

  Although there is no restriction | limiting in the thickness of the surface layer 11, 1.0-10 mm is preferable and 1.5-5 mm is more preferable. If the thickness exceeds the upper limit of the above range, the high-viscosity absorption object cannot quickly pass through the surface layer made of the nonwoven fabric (β), and the surface layer hinders the absorption and retention of the high-viscosity absorption object by the absorption layer. End up. As a result, the high-viscosity absorption object diffuses greatly on the surface layer. Moreover, the water decomposability of the nonwoven fabric (β) is also reduced. When the thickness is less than the lower limit of the above range, the effect as a layer constituting the absorbent body is not achieved, and the effect of providing the nonwoven fabric (β) cannot be expected.

<Method for producing absorber>
The absorbent body 10A in FIG. 1 can be manufactured by a method of manufacturing a nonwoven fabric (α) that constitutes the absorbent layer 12 and a nonwoven fabric (β) that constitutes the surface layer 11, respectively, and stacking them.

(Manufacture of non-woven fabric (α))
The nonwoven fabric (α) can be produced by a method in which an air laid web is formed from raw material fibers (Xs), and the air laid web is heat treated to bond the fibers together.

Specifically, first, an air permeable carrier sheet is arranged on a mesh-like endless belt, and raw material fibers (Xs) are mixed in the air on the air permeable carrier sheet by an air laid type web forming apparatus. An airlaid web is obtained by depositing to form a web (web forming step).
Airlaid web forming apparatuses generally include a nozzle that discharges an intake air flow for uniformly mixing raw fibers (Xs) in air, and a suction box disposed below the mesh endless belt. The intake air flow passes through the mesh endless belt and is sucked into the suction box. When the raw material fibers (Xs) are supplied to the web forming apparatus, the raw material fibers (Xs) are mixed by the intake air flow and dropped onto the mesh-like endless belt, and then on the air-permeable carrier sheet fed out onto the mesh-like endless belt. Deposits and an airlaid web is formed.

  The air permeable carrier sheet is not particularly limited as long as it can pass an intake air flow and can hold an air laid web.

Next, the air laid web is heat treated to bond the fibers together (fiber bonding step). The heat treatment can be performed by a general thermal bond method such as a method of introducing an air laid web into a heating furnace or a method of treating an air laid web with hot air.
As the hot air treatment, a method in which the web is heat-treated by passing through a through air dryer provided with a rotating drum having air permeability on the peripheral surface (hot air circulation rotary drum method), or the web allows hot air to penetrate the web. The method (hot air circulation conveyor oven system) etc. which are heat-processed by passing through the box type dryer which can be mentioned.
In addition, the thermal bond method by a hot air process may be called an air through method or a through air method.

The heat treatment temperature is equal to or higher than the melting point of the resin (A) contained in the air laid web. When the air laid web contains the resin (B), the heat treatment temperature is set to a temperature lower than the melting point of the resin (B). By performing heat treatment at such a temperature, at least a part of the resin (A) is melted to act as a binder, and the fibers are bonded to each other through the melted resin (A).
When the airlaid web includes latent crimped fibers, the heat treatment in the fiber bonding step may also serve as a heat treatment for revealing the crimps of the latent crimped fibers. Alternatively, before and after the fiber bonding step, a heat treatment step for revealing the crimp of the latent crimp synthetic fiber may be provided separately.

The apparent density, basis weight, thickness, and the like of the nonwoven fabric (α) adjust the type of fiber used for the raw fiber (Xs), the use ratio, the amount of raw fiber (Xs) deposited per unit area of the permeable carrier sheet, and the like. Although it can control by this, you may perform a hot press process for the purpose of fine-tuning the density and thickness of a nonwoven fabric, etc. after a fiber bonding process. In this case, the pressing pressure is, for example, a linear pressure of 80 kg / cm or less, preferably a linear pressure of 20 kg / cm or less, and is performed at a pressure smaller than that of a hot press process generally performed as a fiber bonding process for bonding fibers together. .
The nonwoven fabric (α) forming the absorption layer 12 is obtained by peeling the air-permeable carrier sheet from the nonwoven fabric thus obtained.
The air-permeable carrier sheet may be left as it is without being peeled off. When leaving as it is without peeling, it is preferable to use a biodegradable carrier sheet as the air-permeable carrier sheet. An example of such a sheet is tissue paper. When leaving the air-permeable carrier sheet, the surface layer 11 is disposed as viewed from the absorption layer 12 so that the air-permeable carrier sheet does not inhibit the absorption of the object to be absorbed applied from the surface layer 11 side. It is necessary to arrange so that there is no side.

As described above, the non-woven fabric (α) obtained by heat-treating the air-laid web employs the air-laid method as the web forming process and the thermal bond method as the fiber bonding process. Excellent.
Suppose that the carding method is adopted as the web forming step. The carding method is a method of forming a sheet-like web from raw fiber having a long fiber length obtained by mechanically rolling a fiber lump using a roller card machine (carding machine). The carding method is the same dry method as the airlaid method, but the nonwoven fabric obtained through the carding method has excellent absorption performance even if the density and thickness are the same as the nonwoven fabric obtained through the airlaid method. do not do.
This is thought to be due to the following reasons. That is, in the airlaid method, since the web is formed by laminating raw material fibers having a short fiber length using an air flow, the raw material fibers are randomly oriented three-dimensionally in the obtained airlaid web. By applying the thermal bond method to such a web, it is considered that a large number of voids suitable for absorbing and holding a high-viscosity absorbent object are formed in the obtained airlaid web. On the other hand, when the web is formed by the carding method, the fibers are oriented almost two-dimensionally in the obtained card web, so that the voids are considered to be reduced.
Moreover, it is thought that by adopting a thermal bond method as a fiber bonding step of the air laid web, fibers can be bonded together while maintaining the voids in the air laid web.

(Manufacture of non-woven fabric (β))
The non-woven fabric (β) manufactures a web from raw material fibers (Ys) (web forming step), and then gives an aqueous solution of an aqueous resin (Ys) as a binder component to the obtained web, and dries the fibers together. It can manufacture by making it (fiber bonding process).

  As the web forming process, since the raw fiber (Ys) contains a biodegradable polyester fiber (Y1) having a fiber length of 20 to 100 mm, the fiber lump is mechanically wound using a roller card machine (carding machine). It is preferable to employ a carding method in which a sheet-like web is formed from the raw material fibers obtained in this way. A normal apparatus can be used as the roller card machine.

As a method for applying an aqueous solution of the water-soluble resin (Y3) to a web obtained by the carding method (hereinafter referred to as “card web”), a dipping method in which the card web is immersed in the aqueous solution, a card A spray method in which the aqueous solution is sprayed onto the web is preferred. The method of bonding fibers by applying and drying an aqueous solution of the binder component in this way is called a chemical bond method.
The concentration of the water-soluble resin (Y3) in the aqueous solution of the aqueous resin (Ys) is preferably 2.0 to 20.0 g / L, and more preferably 5.0 to 10.0 g / L. When the concentration is within the above range, the raw material fibers (Ys) can be sufficiently bonded, and there is no feeling of tingling, and it is easy to obtain a non-woven fabric (β) excellent in texture and touch.

The aqueous solution of the provided water-soluble resin (Y3) can be dried using a general drying apparatus. For example, the hot-air circulation rotary drum method and the hot-air circulation conveyor oven method described in the nonwoven fabric (α) are adopted. May be.
The drying temperature is preferably 100 to 140 ° C, for example.

  When the carded web contains latent crimped fibers, the step of drying the aqueous solution of the water-soluble resin (Y3) in the fiber bonding step may also serve as a heat treatment for revealing the crimps of the latent crimped fibers. Good. Alternatively, before and after the fiber bonding step, a heat treatment step for revealing the crimp of the latent crimp synthetic fiber may be provided separately.

In this way, the nonwoven fabric (β) forming the surface layer 11 is obtained.
The apparent density, basis weight, thickness, and the like of the nonwoven fabric (β) can be controlled by adjusting the types of fibers used for the raw fiber (Ys), the use ratio, the use ratio of the water-soluble resin (Y3), and the like. .

The nonwoven fabric (α) obtained as described above is used as the absorbent layer 12, and the nonwoven fabric (β) forming the surface layer 11 is overlaid on the entire surface of one of the surfaces to obtain the absorbent body 10A of FIG.
The nonwoven fabric (α) and the nonwoven fabric (β) may be simply overlapped or at least partially bonded. In the case of bonding, for example, a method of bonding by separately using a heat-fusible adhesive component such as a powder made of resin (A), a non-woven fabric (α) and a non-woven fabric (β ) And heat-treating the nonwoven fabric (α) so as to adhere at least a part of the nonwoven fabric (α) and the nonwoven fabric (β) by utilizing the heat-fusibility of the resin (A) contained in the nonwoven fabric (α). Etc.

  Moreover, in the above description, although the nonwoven fabric ((alpha)) which comprises the absorption layer 12, and the nonwoven fabric ((beta)) which comprises the surface layer 11 were each manufactured and illustrated, the nonwoven fabric ((alpha)) is manufactured. The absorbent body 10A of FIG. 1 can also be manufactured by a method in which the nonwoven fabric (β) is used as the air-permeable carrier sheet and the nonwoven fabric (β) is arranged as it is without peeling.

(2) Second Embodiment FIG. 2 is a longitudinal sectional view showing a configuration of an absorbent body 10B according to a second embodiment of the present invention.
The absorber 10B of this example has a three-layer structure in which a surface layer 11 is laminated on the entire surface of one surface of the absorbent layer 12, and a water absorbing layer 13 described below is laminated on the entire surface of the other surface of the absorbent layer 12. It is. The absorbent body 10B of the second embodiment is different from the first embodiment in that it has a water absorption layer 13.

<Water absorption layer>
The water-absorbing layer 13 in this example is a non-woven fabric (γ that is formed by heat-treating an air-laid web formed from raw fiber (Zs) containing cellulose fibers and heat-sealing with heat-fusible fibers contained in the raw fiber (Zs). ). The water absorption layer 13 is included in the absorption target applied from the surface layer 11 side, and is provided for the purpose of mainly absorbing water that is difficult to be retained in the absorption layer 12. Therefore, each layer is arrange | positioned so that the absorption layer 12 may be located between the surface layer 11 and the water absorption layer 13. FIG.

  Since the nonwoven fabric (γ) includes cellulose fibers that are hydrophilic, the nonwoven fabric is excellent in water absorption and biodegradability. Moreover, when it is the nonwoven fabric obtained from the air laid web like this example, it is bulky and is excellent in water absorption. Moreover, when the airlaid web is a non-woven fabric heat-sealed with heat-fusible fibers, the raw fibers (Zs) are mainly point-bonded. Therefore, the bond strength is controlled by the blending ratio of the heat-fusible fiber, and water decomposability can be imparted.

As a cellulose fiber, the various cellulose fiber conventionally used for the absorber can be used, As above-mentioned, a pulp, rayon, cotton, a cupra etc. are mentioned, One or more types can be used. Especially, as a cellulose fiber used for raw material fiber (Zs), pulp fiber is preferable at points, such as fiber length, productivity, and raw material price. Moreover, a pulp fiber is preferable also in the point with few foreign materials to contain.
Examples of the pulp fiber include wood pulp (conifers, hardwoods), rug pulp, linter pulp, linen pulp, non-wood pulp such as straw, three bases, and husk pulp, and raw pulp such as waste paper pulp. As the raw material pulp, any of mechanical pulp (GP, RGP, TMP, etc.) and chemical pulp (sulfite pulp, kraft pulp, etc.) can be used. Among these, kraft pulp is preferable from the viewpoints of supply amount, quality stability, cost, and the like.

The fiber length of the pulp fiber is preferably 4 mm or less, and more preferably 3 mm or less.
As the pulp fiber, normal wood pulp or the like can be used, but the courseness required by the average length weight is 0 because it is a low-density nonwoven fabric and is easy to mix with other fibers. .1 mg / m to 0.3 mg / m, preferably 0.12 mg / m to 0.25 mg / m are suitably used.

  The raw fiber (Zs) preferably contains a heat-fusible fiber that acts as a binder and contributes to the shape retention of the nonwoven fabric (γ). As the heat-fusible fiber, for example, the above-described biodegradable heat-fusible fiber (X) described in the absorbent layer 12 is preferably contained. The raw material fibers (Zs) include any fibers other than the heat-fusible fibers and cellulose fibers (for example, the above-mentioned high melting point fibers, PVA fibers, natural fibers other than cellulose fibers, etc.) as necessary. But you can.

The content of the cellulose fiber in the raw fiber (Zs) is preferably 5 to 98% by mass, and more preferably 50 to 95% by mass. The content of the heat-fusible fiber in the raw fiber (Zs) is preferably 5 to 15% by mass, and more preferably 5 to 10% by mass.
When the content of each fiber is within the above range, the water absorption, biodegradability, water decomposability and shape retention of the nonwoven fabric (γ) are excellent. When the shape retention of the nonwoven fabric (γ) is excellent, even when the liquid absorption amount of the nonwoven fabric (γ) is saturated, the thickness decrease due to the weight of the liquid is small, and external force is applied to the nonwoven fabric (γ). Sometimes the thickness is hard to decrease. Therefore, a decrease in the amount of liquid that can be absorbed due to a decrease in thickness can be suppressed.

  The total ratio of cellulose fibers and heat-fusible fibers in the raw material fibers (Zs) is preferably 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass or more. When the total ratio is 50% by mass or more, the liquid retention property, water disintegration property, and biodegradability of the nonwoven fabric (γ) are improved. The upper limit of the ratio is not particularly limited, and may be 100% by mass, and can be appropriately set in consideration of other fibers arbitrarily blended. When the above-mentioned high melting point fiber is contained as an arbitrary fiber, the content of the high melting point fiber in the raw material fiber (Zs) is preferably 3 to 48% by mass.

The fiber length of the heat-fusible fiber used for the raw fiber (Zs) is preferably 2 to 20 mm, more preferably 2 to 10 mm, like the biodegradable heat-fusible fiber (X) described above. -6 mm is more preferable. With such a fiber length, when forming an airlaid web, these fibers are randomly layered three-dimensionally, resulting in a bulky and non-woven fabric (γ) that exhibits excellent liquid retention. It is easy to be done. Moreover, it becomes difficult to lose shape.
The fineness of the heat-fusible fiber used for the raw fiber (Zs) is preferably 0.5 to 74 dtex, more preferably 0.8 to 35 dtex, like the biodegradable heat-fusible fiber (X) described above. 1.0 to 20 dtex is more preferable. With such a fineness, it is easy to obtain a nonwoven fabric (γ) that is bulky and exhibits excellent liquid retention. In addition, it is difficult to lose shape and is excellent in touch.
One or more heat-fusible fibers can be used.

The basis weight of the nonwoven fabric (gamma) is preferably 30~1000g / ^{m 2,} more preferably 40~700g / ^{m 2,} more preferably 50 to 500 g / ^{m 2.} When the basis weight is equal to or higher than the lower limit value of the above range, the ability to hold the liquid is excellent, and when the basis weight is equal to or lower than the upper limit value of the above range, the wearing feeling and handling properties of the absorbent body 10B are excellent.
Density of the nonwoven fabric (gamma) is preferably from 0.01 to 0.1 g / cm ^3, more preferably 0.01~0.08g / cm ^3, more preferably 0.02~0.06g / cm ^3. If the density exceeds the upper limit of the above range, there are few voids in the nonwoven fabric (γ) or the size of the voids is too small, and the absorption rate may be slow. If the density is less than the lower limit of the above range, there is a possibility that the voids in the nonwoven fabric (γ) will be excessively large or the size of the voids will be excessively large. Therefore, when the liquid absorption amount of the nonwoven fabric (γ) becomes saturated, the thickness decrease due to the weight of the liquid becomes large, and the thickness tends to decrease when an external force is applied to the nonwoven fabric (γ). As a result, the amount of liquid that can be absorbed by the nonwoven fabric (γ) is reduced, and even if the liquid is once absorbed, it is difficult to hold and there is a risk of reversal.

  The water absorption layer 13 may contain components other than the raw material fibers (Zs) such as the above-described known functional additives as necessary.

(3) Third Embodiment FIG. 3 is a longitudinal sectional view showing a configuration of an absorbent body 10C according to a third embodiment of the present invention.
The absorbent body 10 </ b> C in this example is provided with a surface layer 11 so as to cover the entire both surfaces of the absorbent layer 12. As a specific form in which the surface layer 11 covers both surfaces of the absorbent layer 12, the nonwoven fabric (β) forming the surface layer 11 is formed into a bag shape, and the nonwoven fabric (α) forming the absorbent layer 12 is disposed therein. Examples include a form, a form in which the nonwoven fabric (β) is wrapped around the nonwoven fabric (α).

(4) Other Embodiments The absorbent body of the present invention is not limited to the first to third embodiments. For example, in an embodiment having a water absorption layer, a form in which a laminate of an absorption layer and a water absorption layer is arranged in a bag-like surface layer is also included.

  As described above, the absorbent body of the present invention has a configuration in which a specific surface layer is laminated on at least a part of the surface of the absorption layer that absorbs and holds a high-viscosity absorption object well. Therefore, the texture and feel are excellent. Moreover, this surface layer is excellent in the permeability | transmittance of a high-viscosity absorption target object, and a high-viscosity absorption target object does not remain on a surface layer. Therefore, the surface layer does not hinder the absorption and retention of the high-viscosity absorption object by the absorption layer. Moreover, since the absorber of the present invention also has water decomposability and biodegradability, it is easy to dispose of and is environmentally friendly.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, this invention is not limited to these Examples.
(Examples 1-8, Comparative Examples 1-9)
In each example, an absorber having a two-layer configuration similar to the absorber 10A shown in FIG. 1 was manufactured. In addition, the comparative example 1 consists only of an absorption layer.
First, an absorption layer (nonwoven fabric (α)) was produced with each formulation shown in Tables 1 to 3.
Specifically, raw fibers of the formulations shown in Tables 1 to 3 are fed to an airlaid web forming machine while feeding tissue paper (air-permeable carrier sheet) onto a mesh endless belt that is mounted on a conveyor and travels. (Xs) was supplied so as to have the basis weight of the absorption layer shown in Tables 1 to 3. Next, while the raw material fibers (Xs) were uniformly mixed in the air, the air-laid web was formed on the tissue paper by being dropped and deposited on the mesh endless belt together with the intake air flow.
Next, this air laid web was passed through a box type dryer (hot air circulating conveyor oven) that allows hot air to pass through the web, and treated with hot air to obtain a nonwoven fabric. The hot air treatment temperature (hot air circulation conveyor oven temperature) was 120 to 140 ° C. Then, tissue paper was peeled off from the nonwoven fabric, and the nonwoven fabric ((alpha)) of the basic weight, thickness, and apparent density which are shown in Table 1-Table 3 was obtained.
The thickness and basis weight are actual values, and the apparent density was calculated from the thickness and basis weight. The thickness was measured with calipers.

On the other hand, a surface layer (nonwoven fabric (β)) was produced with each formulation shown in Tables 1 to 3.
Specifically, using a roller card machine (carding machine), a sheet-like card web was formed from raw material fibers (Ys) obtained by mechanically winding a fiber lump.
Next, the obtained card web is immersed in a tank in which an aqueous solution of PVA resin (PVA resin concentration: 5.0 g / L), which is a water-soluble resin (Y3), is put, and the water-soluble resin (Y3) is attached. After (dipping method), it was dried with a drum-type drying apparatus. Under the present circumstances, the aqueous solution of PVA resin was made to adhere so that the PVA mass per unit area of a surface layer (after drying) might become the value of Tables 1-3. The drying temperature was 130 ° C. In this way, nonwoven fabrics (β) having the basis weight, thickness, and apparent density shown in Tables 1 to 3 were obtained.
The thickness and basis weight are actual values, and the apparent density was calculated from the thickness and basis weight. The thickness was measured with calipers.

The non-woven fabric (α) and non-woven fabric (β) obtained as described above were stacked one by one to obtain absorbers of respective examples.
About the absorber of each example, the high-viscosity liquid absorptivity, texture, and water decomposability were evaluated by the following methods. The results are shown in Tables 1 to 3.

The abbreviations in the table indicate the following contents.
PLA is polylactic acid, and PBS is polybutylene succinate.
PLA / PLA fiber (1): PLA side-by-side hollow latent crimped fiber of different molecular weight, fineness of 17 dtex, fiber length of 5 mm
PLA / PLA fiber (2): PLA side-by-side hollow latent crimped fiber of different molecular weight, fineness of 17 dtex, fiber length of 64 mm
PLA / PLA fiber (3): PLA side-by-side hollow latent crimped fiber of different molecular weight, fineness 6.6 dtex, fiber length 64 mm
PBS / PLA fiber: core-sheath type latent crimped fiber, fineness 17 dtex, mass ratio (PBS / PLA) = 6/4, fiber length 5 mm (sheath: PBS, core: PLA)
PLA fiber: Fineness 1.7dtex, fiber length 51mm
PVA fiber: Fineness 2.2dtex, fiber length 6mm
Rayon fiber (1): Fineness 17 dtex, fiber length 44 mm
Rayon fiber (2): Fineness 5.5 dtex, fiber length 44 mm
Rayon fiber (3): Fineness 3.3 dtex, fiber length 44 mm

<High viscosity liquid absorbency>
(1) A sample obtained by cutting the absorbent body obtained in each example into 10 × 10 cm was used as a sample, and this was fixed to a horizontal surface. In addition, it fixed so that a surface layer might be located upwards and an absorption layer might contact | connect a horizontal surface.
(2) 2 ml of high-viscosity liquid was put into a syringe and dropped onto the surface of the center of the sample. As the high viscosity liquid, an aqueous solution in which bentonite, glycerin, water and a polymer thickener were mixed and adjusted to a viscosity of 500 mPa · s at 23 ° C. was used.
(3) A roller with a diameter of 100 mm whose surface was water repellent was slowly (once rotated 1 second) on the dropped liquid. The roller load (linear pressure) was 7 g / cm.
(4) The width (a) and length (b) of the high-viscosity liquid spreading on the sample surface were measured, and the area of the diffused liquid (diffusion area) was calculated. Note that the shape of the diffused liquid was regarded as an ellipse, and the area was determined by the calculation formula “area = π × a × b / 4”.
The smaller the diffusion area calculated in (4) above, the better the high viscosity liquid absorbency.
In this example, if the diffusion area is 50 cm ² or less, it can be determined that the high viscosity liquid absorbability is excellent.

<Texture>
As the evaluation item, the waist, the beam, the slime, the soft feeling, the softness, and the softness when touched were adopted as evaluation items, and these were comprehensively judged and subjected to the following five-level sensory evaluation.
A: Good in all respects and excellent in texture.
A: Slightly inferior in one item, such as slightly repulsive and slightly inferior.
○: Inferior in one item such as resilience and low softness.
Δ: Two items are inferior, or one item is extremely inferior.
X: Inferior in 3 or more items, or remarkably inferior in 2 or more items.

<Water decomposability>
A sample obtained by cutting the absorbent body obtained in each example into 3 × 3 cm and a 300 ml beaker containing 300 ml of water were placed on a magnetic stirrer, and a disc-shaped rotor having a diameter of 35 mm and a thickness of 12 mm was used. Stir for 3 minutes. The collapse state of the sample before and after stirring was visually confirmed and evaluated in the following five stages.
A: The sample is disintegrated and hydrolyzed.
(Double-circle): The sample has collapsed | disintegrated and has almost hydrolyzed.
○: The sample is almost collapsed and the original shape is not retained.
Δ: The sample is collapsed, but the shape remains slightly.
X: The sample collapses partially, and the original remains.

As shown in Tables 1 to 3, according to the absorbent body of each example, the high-viscosity liquid absorbability was excellent, and the texture and water decomposability were also excellent.
On the other hand, the absorbent body of each comparative example does not have a surface layer, or even if it has a surface layer, the structure of the surface layer is not appropriate. At least one of them was inferior.
Since Comparative Example 1 did not have a surface layer, “slimming” was particularly inferior among texture evaluation items.
In Comparative Example 2, since the density of the surface layer is high, the high-viscosity liquid cannot quickly permeate the surface layer and has a large diffusion area. Comparative Example 3 has the same tendency.
In Comparative Example 4, since the amount of the water-soluble resin (Y3) contained in the surface layer is large, the water-soluble resin (Y3) has a poor high-viscosity liquid absorbability due to the blockage of the voids of the nonwoven fabric (β). In addition, since the surface layer of the comparative example 4 has a small basis weight and is relatively thin, the texture is relatively good.
In Comparative Example 5, the amount of cellulose fibers (Y2) contained in the surface layer is large and the fineness of the cellulose fibers (Y2) is small, so that the apparent density of the surface layer is increased and the adhesion is too strong. Therefore, a decrease in water disintegration, a decrease in texture (feeling of tingling), and a decrease in absorbability of high viscosity liquid are observed.
In Comparative Example 6, since the fineness of the biodegradable polyester fiber (Y1) and cellulose fiber (Y2) contained in the surface layer is small, the apparent density of the surface layer is high and the texture is inferior. However, since the thickness of the surface layer is thin, the high viscosity liquid absorbability is good. Moreover, since cellulose fiber (Y2) is less than Comparative Example 5, most of the water-soluble resin (Y3) adheres to the biodegradable polyester fiber and does not excessively adhere to the cellulose fiber (Y2). It is good. Comparative Example 7 tends to have the characteristics of Comparative Examples 5 and 6.
Since the comparative example 8 contains many cellulose fibers (Y2) with high fineness in the surface layer, the apparent density is low, but the amount of the water-soluble resin (Y3) is large and the water disintegrability is poor.
Comparative Example 9 has a surface layer having a basis weight and an apparent density lower than those of Comparative Example 5, but since the amount of cellulose fibers (Y2) contained in the surface layer is large, a water-soluble resin (Y3 ) Adheres excessively to the cellulose fibers (Y2) and is inferior in water disintegrability.

10A, 10B, 10C Absorber 11 Surface layer 12 Absorbing layer 13 Water absorbing layer

Claims (9)

An absorber in which a surface layer is laminated on at least a part of the surface of the absorption layer,
The absorbent layer is made of raw material fibers (Xs) containing 2 to 50% by mass of at least one biodegradable heat-fusible fiber (X) selected from the following fibers (x1) and the following fibers (x2). The airlaid web is heat treated, and the nonwoven fabric (α) having an apparent density of 0.015 to 0.045 g / cm ³ ,
The surface layer comprises a raw fiber (Ys) containing a biodegradable polyester fiber (Y1) and a cellulose fiber (Y2) having a fiber length of 20 to 100 mm, and a water-soluble resin (Y3) represented by the following formula (1) and It contains so that the mass ratio represented by (2) may be satisfy | filled, It consists of a nonwoven fabric ((beta)) whose apparent density is 0.005-0.045 g / cm < ³ >, and a basic weight is 10-100 g / m < ² >. Absorber.
Fiber (x1): polybutylene succinate, poly (hydroxybutyrate / hydroxyhexanoate), polycaprolactone, poly (caprolactone / butylene succinate), poly (butylene succinate / adipate), poly (butylene succinate / carbonate) ), At least one resin (A) selected from poly (butylene adipate / terephthalate) and polyethylene succinate.
Fiber (x2): at least one resin (B) selected from polylactic acid, polyhydroxybutyrate, polyglycolic acid and cellulose acetate, and the resin (A), and at least a part of the surface of the resin (B) A) biodegradable heat-fusible fiber.
0.75 ≦ Y1 / Y2 ≦ 30 (1)
0.002 ≦ Y3 / (Y1 + Y2) ≦ 0.3 (2)   The absorbent body according to claim 1, wherein the biodegradable polyester fiber (Y1) is a latent crimped fiber.   The absorber according to claim 1 or 2, wherein the raw fiber (Ys) is chemically bonded with the water-soluble resin (Y3).   The fiber length of the said cellulose fiber (Y2) is 20-100 mm, The absorber as described in any one of Claims 1-3 characterized by the above-mentioned.   The said water-soluble resin (Y3) is polyvinyl alcohol, The absorber as described in any one of Claims 1-4 characterized by the above-mentioned. The basic weight of the said nonwoven fabric ((alpha)) is 50-1200 g / m < ² >, The absorber as described in any one of Claims 1-5 characterized by the above-mentioned.   It further has a water absorption layer made of a nonwoven fabric (γ) formed from raw fiber (Zs) containing 5 to 98% by mass of cellulose fiber, and the absorption layer is located between the water absorption layer and the surface layer. The absorbent body according to any one of claims 1 to 6, wherein The apparent density of the nonwoven fabric (α) is 0.016 to 0.020 g / cm. ³ The apparent density of the nonwoven fabric (β) is 0.005 to 0.04 g / cm. ³ The absorber according to any one of claims 1 to 7. The thickness of the said absorption layer is 5-40 mm, and the thickness of the said surface layer is 1.0-5 mm, The absorber as described in any one of Claims 1-8.

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