TWI654349B - Liquid holding sheet and mask - Google Patents

Abstract

The present invention provides a liquid-retaining sheet which is formed of a nonwoven fabric containing 50% by mass or more of a high elastic fiber having a Young's modulus of 30 cN/T or more. The aforementioned high elastic fiber may be a core-sheath type composite fiber. The sheath portion of the core-sheath type composite fiber may be formed of an ethylene-vinyl alcohol copolymer, and the core may be formed of a hydrophobic resin. The average elastic density of the aforementioned high elastic fibers may be about 1.5 to 10 dtex. In the state in which the liquid-retaining sheet is impregnated with a liquid component such as a cosmetic liquid, even if it is pressed by a finger, the sucking of the liquid component is fast, and it is suitable for the mask.

Description

Liquid holding sheet and mask

The present invention relates to a liquid-retaining sheet which can absorb a liquid component (liquid compound), in particular, a liquid component which is impregnated with a liquid component containing a cosmetic component or a medicinal component, and which is attached to the skin and used for a mask.

In the past, a skin care sheet (a liquid film containing a liquid impregnated with a liquid) impregnated with a cosmetic or the like has been used as a sheet attached to human skin (skin) or the like. Since the skin care sheet represented by the mask can easily maintain the skin in a high-humidity state, various products have been developed in recent years. Among them, the mask has a function of conveying the cosmetic liquid (cosmetic material) impregnated into the sheet including the mask to the skin, but the beauty liquid must be conveyed so that the sheet itself adheres to the skin. Therefore, in order to make the sheet contact the skin well, the mask is subjected to various efforts for the sheet itself or the shape.

Japanese Laid-Open Patent Publication No. 2008-261067 (Patent Document 1) discloses a solvent having a fiber length of 30 to 60 mm, which is excellent in water-repellent property, water retention property, release property, and form stability. a non-woven fabric sheet in which a spun cellulose fiber and a core-sheath type composite fiber are entangled with each other, and the core-sheath type composite fiber is formed by a sheath portion and a core portion. The sheath portion is an ethylene-vinyl alcohol-based copolymer, and the core portion is a nonwoven fabric sheet made of a hydrophobic resin and having a diameter of 5 to 15 μm. In this document, the method for producing a core-sheath type composite fiber is described as having a heat extension, but specific conditions are not described.

However, the nonwoven fabric sheet is excellent in flexibility or liquid retention, but the sheet has a small thread (rigidity). When the mask is pressed against the face and pressed by a finger, the thickness is restored and the cosmetic liquid (cosmetic material) is used. Slow suck back. Therefore, it is difficult for the beauty liquid to effectively travel throughout the face. In particular, it is necessary for the mask to be pressed with a finger to press a portion to be supplied to the cosmetic liquid or a portion that is difficult to adhere to. Therefore, in the conventional mask, although the mask is adhered to the target site, it is in a state in which the supply of the cosmetic liquid is insufficient.

In addition, in order to improve the conformability of the mask to the skin (face), a mask having a layer formed of ultrafine fibers on the skin contact side or a mask having a three-dimensional structure is also developed. However, the current state of the art is that even if the mask is insufficient for the skin, it is necessary to repeat the action of pressing the mask with a finger. Therefore, by repeatedly pressing the skin, the cosmetic liquid accumulated by the pressed portion is pressed to some extent (exuded to the periphery of the pressing portion), and as a result, the state in which the cosmetic liquid is insufficient is promoted.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2008-261067 (Request) 1, paragraph [0033])

Accordingly, an object of the present invention is to provide a liquid-retaining sheet and a mask which are quickly sucked back by a liquid component even when pressed with a finger in a state in which a liquid component such as a cosmetic liquid (cosmetic material) is impregnated.

Another object of the present invention is to provide a liquid retaining sheet and a mask which are quick in recovery of thickness even when pressed with a finger in a state in which a liquid component is impregnated.

Still another object of the present invention is to provide a liquid retaining sheet and a mask which are effective for replenishing a desired portion of a cosmetic liquid.

Another object of the present invention is to provide a liquid holding sheet and a mask which are excellent in flexibility, liquid retention, liquid release property, and form stability.

In order to solve the above problems, the present inventors have actively reviewed the results and found that a specific high elastic fiber is used as the main fiber to form a non-woven fabric which can absorb the liquid component, and by controlling the thickness direction of the liquid holding sheet to reset the compression, In the state in which a liquid component such as a cosmetic liquid is impregnated, even if the finger is pressed, the liquid component can be quickly sucked back, and thus the present invention has been completed.

That is, the liquid-retaining sheet of the present invention is formed of a nonwoven fabric containing 50% by mass or more of a high elastic fiber having a Young's modulus of 30 cN/T or more. The aforementioned high elastic fiber may be a core-sheath type composite fiber. The sheath portion of the core-sheath type composite fiber may be formed of an ethylene-vinyl alcohol copolymer, and the core may be formed of a hydrophobic resin. The hydrophobic resin may be a polyester resin. The average elastic density of the aforementioned high elastic fibers may be about 1.5 to 10 dtex. The high elastic fiber may be a fiber obtained by extending 2.4 times or more at a temperature of 80 ° C or higher. The nonwoven fabric may further comprise a cellulose-based fiber having an average fineness of 0.3 to 5 dtex. The mass ratio of the high elastic fiber to the fiber fiber is high elastic fiber/cellulose fiber = 60/40 to 80/20. The liquid retaining sheet of the present invention may also be a skin care sheet (especially a mask) impregnated with a liquid component containing a cosmetic. When the liquid-retaining sheet of the present invention is impregnated with a cosmetic liquid having a self-weight of 900% by mass and loaded under a load of 260 g/cm ² for 1 minute and then removed, the reduction in compression in the thickness direction is 60% or more at 5 minutes.

The present invention uses a specific high elastic fiber as a main fiber to form a non-woven fabric which can absorb a liquid component, and controls the liquid to maintain the thickness direction of the sheet to restore the compression, so that even in the state of impregnating the liquid component such as a cosmetic liquid, even With a finger press, the back absorption of the liquid component is still rapid. Further, in the state in which the liquid component is impregnated, even if the finger is pressed, the thickness is restored (the compression elasticity in the thickness direction when the cosmetic liquid is impregnated) is fast. Therefore, for example, it can be utilized as a mask, and it can effectively replenish (grant) a cosmetic liquid to a desired part of the face. Furthermore, by using ethylene-vinyl alcohol copolymerization The core-sheath type composite fiber of the sheath formed by the object can improve softness, liquid retention, liquid release property, and form stability.

In the present specification, the compressive elasticity in the thickness direction (the compressive elasticity at the time of impregnation) in the impregnation of the cosmetic liquid means that the sheet is impregnated with the cosmetic liquid, and the sheet is compressed at a specific time and load (after crushing), and the load is removed. The characteristic (%) of how much the thickness of the crushed sheet is restored to the original (the degree of recovery of the compressed sheet thickness).

1‧‧‧ Laser Displacement Meter

2, 12‧‧‧ load

3, 13‧‧‧ samples

4, 14‧‧‧ measuring table

Fig. 1 is a schematic view for explaining a method of measuring the compressive elasticity in the thickness direction when the cosmetic liquid is impregnated in the embodiment.

Fig. 2 is a schematic view for explaining a method of measuring the back suction of a liquid in the embodiment.

[non-woven]

The liquid holding sheet of the present invention is formed of a non-woven fabric which can absorb a liquid component (especially an aqueous liquid component). Non-woven fabrics are used to impregnate ingredients containing ingredients or efficacy (eg, moisturizing ingredients, cleansing ingredients, sweating ingredients, perfume ingredients, whitening ingredients, blood circulation promoting ingredients, cooling ingredients, ultraviolet light absorbing ingredients, skin itching inhibitors) The liquid component (liquid compound) required for wettability and voids for liquid retention, In the operation, the liquid does not drip, and can be maintained to cover a specific part of the body (for example, the face), and the liquid cosmetic material is slightly moved to the side of the skin while being attached or left standing. The liquid holding sheet (non-woven fabric) of the invention has excellent liquid retaining property, and has moderate resilience or elasticity. When the liquid component is impregnated, the compression is reset and the liquid is sucked back quickly, in particular, the specific elastic fiber is specified. When the non-woven fabric is formed, the liquid is excellent in suckback property and the thickness is also quickly recovered, so that it can be returned to the same liquid holding state as the uncompressed portion in a short time.

In the case of the reduction, specifically, the beauty liquid which is impregnated with respect to the self-weight of 900% by mass and is loaded with a load of 260 g/cm ² for 1 minute and then removed, the reduction of the compression in the thickness direction is 60% or more at 5 minutes ( 60~100%), preferably 65~99%, more preferably 70~98%. When the reset is less than 60%, the liquid component such as the cosmetic liquid cannot be sufficiently sucked back to the pressing portion. Further, the details of the compression reset can be measured by the method described in the examples below.

The liquid sucking, specifically, the liquid of the beauty liquid after 5 minutes after the impregnation of the beauty liquid with respect to the self-weight of 900% by mass and the partial load of 620 g in a circular shape of 1.2 cm in diameter is removed for 1 minute. The suckback is 55% or more (55 to 100%), preferably 60 to 99%, more preferably 65 to 98%, and even more preferably 70 to 97%. When the liquid is sucked back too low, the liquid component after pressing is insufficient, and the cosmetic liquid cannot sufficiently penetrate into the skin when it is a mask. Further, the liquid resorption of the cosmetic liquid can be measured in detail by the method described in the examples below.

Non-woven fabric (liquid holding sheet) is also excellent in softness when wet The fibers are moderately complexed so as to be applied to the skin such as the face, and the stress is 30% elongation according to JIS L1913, and the stress is, for example, 0.5 to 10 N/5 cm in at least one direction, preferably 1 to 1. 8N/5cm, preferably about 1.5~5N/cm. When the stress is too small when stretched, it is difficult to excessively stretch when worn on the skin such as the face, and when it is too large, the adhesion to the skin is lowered. Further, the stress at 30% elongation in the wet state can be measured in detail by the method described in the examples below.

The liquid retaining ratio of the non-woven fabric (liquid holding sheet) is also excellent, and the water retention rate according to JIS L1907 7.2 may be 800% or more, for example, 900 to 3000%, preferably 950 to 2000%, more preferably about 1000 to 1500%. When the water retention rate is too low, it is difficult to supply a sufficient amount of cosmetics (cosmetic liquid) to the skin.

The weight per unit area of the nonwoven fabric is, for example, 30 to 100 g/m ² , preferably 35 to 80 g/m ² , more preferably 40 to 70 g/m ² (especially 50 to 65 g/m ² ). When the weight per unit area is too small, it is difficult to secure a void for liquid retention by fibers. On the other hand, when it is too large, since the thickness becomes large, the conformability to the skin is lowered. Moreover, the amount of liquid retention is increased, and most of the performance components are unable to reach the skin and remain in the liquid retaining layer, which tends to waste unnecessary performance components.

The thickness of the non-woven fabric may be selected from the range of about 100 to 3000 μm, for example, 200 to 2000 μm, preferably 300 to 1500 μm, more preferably 400 to 1200 μm (especially 500 to 1000 μm).

(high elastic fiber)

The non-woven fabric contains a high elastic fiber having a Young's modulus (initial tensile strength) of 30 cN/T or more (for example, about 40 to 500 cN) as a main fiber in order to have appropriate threading or elasticity. The Young's modulus of the high elastic fiber may also be about 30 to 100 cN/T (for example, 30 to 90 cN/T), preferably 30 to 80 cN/T (for example, 35 to 70 cN/T), more preferably 40 to 60 cN. /T (especially 45~55cN/T). When the Young's modulus is too low, the backlash and elasticity of the non-woven fabric cannot be improved.

The structure of the high elastic fiber is not particularly limited as long as it has the aforementioned Young's modulus, and may be, for example, a polyester fiber such as polyethylene terephthalate or a polyphenylene sulfide fiber of polyphenylene sulfide (single phase fiber) However, it is preferable to use a core-sheath type composite fiber in terms of elasticity, liquid retention, and liquid release property.

In the core-sheath type composite fiber, in order to ensure wettability or liquid retention, the sheath portion preferably contains a hydrophilic resin. The sheath portion including the hydrophilic resin serves as an important role for inhaling the liquid into the interior of the nonwoven fabric when a liquid such as a cosmetic (cosmetic liquid) is attached to the liquid holding sheet, and serves as a large amount of cosmetic liquid which is once sucked into the nonwoven fabric. It is kept in a role that does not drip the liquid at the time of operation.

The hydrophilic resin is exemplified by a resin having a hydrophilic group (particularly a hydroxyl group) such as a hydroxyl group, a carboxyl group or a sulfonic acid group in the molecule, but is preferably a hydrophilic resin having a hydroxyl group in a monomer unit, and particularly has a molecularly uniform property. From the viewpoint of a hydroxyl group, an ethylene-vinyl alcohol-based copolymer is preferred. The ethylene-vinyl alcohol-based copolymer has biocompatibility based on hydrophilicity, non-absorbability, and thermal conductivity. In addition, the ethylene-vinyl alcohol copolymer is not only hydrophilic but also moderately lipophilic, not only for the liquid retention of the cosmetic liquid, but also Highly adherent or skin-sensitive to the skin containing fatty or watery, including sweat or dirt.

In the ethylene-vinyl alcohol copolymer, the content of the ethylene monomer (copolymerization ratio) may be selected from the range of about 25 to 70 mol%, and may be 30 to 65 from the viewpoint of hydrophilicity and melt spinning property. The molar amount is about 5%, and it is possible to suppress the problem of melt spinning due to deterioration of the retained resin, and may be, for example, 35 to 60 mol%, preferably 37 to 55, in terms of hydrophilicity. Mole%, better about 40~50 mol%. When the ratio of the ethylene unit is too large, the hydrophilicity is lowered, and when it is too small, the melt spinning property is lowered, and the form stability in a wet state is lowered.

The degree of saponification of the vinyl alcohol unit may be 80 mol% or more, and is 90 mol% or more (for example, 90 to 99.99 mol%), preferably 95 mol%, from the viewpoint of hydrophilicity and melt spinning property. The above (for example, 95 to 99.98 mol%), more preferably about 96 to 99.97 mol%. When the degree of saponification is too small, hydrophilicity and heat resistance are lowered.

Further, in order to improve the stability to hot water, the ethylene-vinyl alcohol-based copolymer is usually subjected to a crosslinking treatment such as acetalization after the fiberization to improve the hot water resistance. However, the present invention requires compatibility with the skin. Therefore, it is better not to be cross-linked as described above.

The ethylene-vinyl alcohol copolymer may also contain other copolymerization units. The polymerization components constituting the copolymerization unit are exemplified by other fatty acid vinyl esters (vinyl propionate, vinyl pivalate, etc.), vinyl decane compounds (vinyl trimethoxy decane, vinyl triethoxy decane, vinyl). Tris(β-methoxy-ethoxy)decane, γ-methylpropenyloxypropylmethoxydecane and many more. These polymeric components may be used singly or in combination of two or more. Among these, a vinyl decane compound such as vinyl trimethoxy decane or vinyl triethoxy decane is preferred. The proportion of the vinyl decane compound is, for example, about 0.0001 to 0.3 mol% (especially 0.0002 to 0.2 mol%) with respect to the entire polymerization component.

The average degree of viscosity of the ethylene-vinyl alcohol copolymer is, for example, 200 to 2,500, preferably 300 to 2,000, more preferably about 400 to 1,500.

When the sheath is formed of an ethylene-vinyl alcohol-based copolymer, it is excellent in adhesion to the skin or skin contact property, and can improve liquid absorbability and retention of the cosmetic material. However, since the rigidity is lowered by water absorption, the rigidity of the nonwoven fabric is maintained. Further, in the processing step, the desired bulkiness (void ratio) can be maintained while ensuring water absorption, and therefore the core portion is preferably formed of a hydrophobic resin which does not have a reduced rigidity due to water absorption.

Examples of the hydrophobic resin include a polyolefin resin, an acrylic resin, a polyvinyl acetal resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, a polyester resin, a polyamide resin, and a polyamine. A fiber or the like formed of a resin component such as a urethane resin. These hydrophobic resins may be used singly or in combination of two or more.

Among these hydrophobic resins, a resin having a predetermined moisture content of less than 2.0% in a standard state (20 ° C, 65% RH) is widely used, for example, a polyolefin resin such as polyethylene or polypropylene which is generally used for nonwoven fabrics. Polyester resin such as polyethylene terephthalate, polybutylene terephthalate or polyethylene naphthalate, polyamine 6, polyamine 6,6, polyamine 4,6 A polyamine group such as a polyamide type resin or a polyester polyol type urethane type resin A fiber formed of a formate resin or a polyacrylonitrile-based resin has a higher elastic modulus than an ethylene-vinyl alcohol-based copolymer and is excellent in spinnability of an ethylene-vinyl alcohol-based copolymer. The polypropylene resin or the polyester resin is preferably a polyester resin from the viewpoints of high modulus of elasticity and high dimensional stability at high temperatures, suppression of shrinkage of the nonwoven fabric, and workability.

The polyester resin is exemplified by a polyarylene dicarboxylate resin such as polyethylene terephthalate, polybutylene terephthalate or polyethylene naphthalate, or an aliphatic polyester such as polylactic acid. Resin or the like. These polyester resins may be used singly or in combination of two or more. Among these polyester resins, a polyarylene dicarboxylic acid C containing an aromatic dicarboxylic acid C _2-4 alkyl diester unit such as 80 ppm by mole or more of ethylene terephthalate or butylene terephthalate _{The 2-4} alkyl diester resin is preferred.

In the core-sheath type composite fiber, the sheath portion preferably occupies an area of 50% or more (especially 90 to 100%) of the surface area of the fiber continuously in the longitudinal direction. Usually, the sheath portion occupies substantially the entire surface area.

The ratio (mass ratio) of the core portion to the sheath portion is, for example, a sheath portion/core portion = 90/10 to 10/90 (for example, 60/40 to 10/90), preferably 80/20 to 15/85, and more. Good for around 60/40~20/80. When the ratio of the sheath portion is too large, the core cannot maintain the shape of the fiber, and it is difficult to ensure the strength of the fiber itself. Further, depending on the core diameter, the fiber yarn is lowered, the density of the nonwoven fabric is increased, and the liquid retainability is lowered. When the ratio of the sheath is too small, the hydrophilicity is lowered. Further, depending on the diameter of the core, the yarn is made too strong, and the flexibility or the conformability to the skin is lowered.

The high elastic fiber may also contain a conventional additive, for example, a stabilizer (a thermal stabilizer such as a copper compound, an ultraviolet absorber, a light stabilizer, an antioxidant, etc.), a colorant, a dispersant, a microparticle, an antistatic agent, a flame retardant, Plasticizer, lubricant, crystallization rate retarder, and the like. These additives may be used singly or in combination of two or more. In particular, in the ethylene-vinyl alcohol-based copolymer of the sheath portion, in order to suppress thermal deterioration during melt molding, a trace amount of an acid (a fatty acid such as acetic acid or the like) or a metal salt (alkali metal or alkaline earth such as phosphoric acid or acetic acid may be added). Metal salts, etc.). These additives may be supported on the surface of the fiber or may be contained in the fiber.

The cross-sectional shape of the high elastic fiber (the cross-sectional shape perpendicular to the longitudinal direction) is not particularly limited, and may be, for example, a circular cross section, a profiled cross section (flat shape, elliptical cross section, etc.), a polygonal section, or a multilobal section (3~) 14 leaf-shaped profiles, hollow sections, V-shaped sections, T-shaped sections, H-shaped sections, Y-shaped sections, I-shaped (dog-bone-shaped) sections, array-shaped sections, and the like. In the above, the shape having the acute angle portion (protrusion portion) or the groove portion such as the polygonal cross section or the Y-shaped cross section is preferably such that the acute touch property is excellent, and it is preferable that the acute angle portion (protrusion portion) or the groove portion is not provided. The shape, in particular, a circular cross section (a slightly round cross section such as a true circular cross section) or an elliptical cross section is more preferable, and a slightly round cross section is preferable.

The average fineness of the high elastic fibers is, for example, 1.5 to 10 dtex, preferably 1.7 to 5 dtex, more preferably 1.8 to 4.5 dtex (especially 1.9 to 4 dtex). Further, the average fineness is, for example, 1.5 to 5 dtex, preferably 1.6 to 3 dtex, more preferably about 1.7 to 2 dtec, from the viewpoint of high water retention rate and excellent characteristics such as suckback of the liquid component. When the high elastic fiber is too thick, Reduced skin contact, easy to reduce liquid absorption or liquid retention. On the other hand, when it is too fine, the elasticity is lowered, so when the non-woven fabric is pressed by a finger, the return of the thickness or the suckback of the liquid component becomes slow. Further, the density of the non-woven fabric becomes high, and the voids between the fibers are reduced, so that the liquid retainability is also lowered.

The fiber length (average fiber length) of the high elastic fiber is not particularly limited, and is, for example, 20 to 70 mm, preferably 30 to 60 mm, more preferably 45 to 60 mm (especially 45 to 55 mm). When the fiber length is too long, the fibers are difficult to uniformly entangle each other, the skin contact property is lowered, and the liquid absorbency and liquid release property are lowered. On the other hand, when the fiber length is too short, the fibers are liable to fall off from the non-woven fabric, and the flexibility or stretchability is also lowered.

The method for producing the high elastic fiber is not particularly limited, and a conventional method can be used. The high elastic fibers can be produced by a spinning method by melt-kneading extrusion, but in order to impart a higher elastic modulus to the fibers, it is preferred to carry out the stretching treatment after spinning. The present invention can improve the crystallinity of a resin component (for example, a polyester resin forming a core) which forms a high elastic fiber by performing elongation treatment at a specific heating temperature after spinning, or can be improved. The rigidity or return of the fiber gives the non-woven fabric the elasticity required for the mask.

The stretching method can utilize a conventional method, for example, a step of extending between the heat guiding wires when the fibers are ejected from the nozzle by a godet roller during spinning, or can be temporarily wound. The two-step method of performing heat extension at a low speed in a water bath or a hot blast stove.

The stretching ratio may be 2.0 times or more, and specifically may be selected from the range of 2 to 10 times, for example, 2.1 to 8 times, preferably 2.2 to 5 times, more preferably 2.3 to 4 times (preferably 2.4 to 3 times). )about. Extension ratio When it is low, the elasticity of the high elastic fiber cannot be sufficiently increased, and when it is too high, the yarn breakage occurs.

The heating temperature for stretching may be selected depending on the type of the fiber, and may be, for example, 80 ° C or higher, preferably 80 to 150 ° C, more preferably 85 to 120 ° C (preferably 85 to 100 ° C).

The high elastic fiber can be subjected to a conventional crimping treatment using a crimping imparting device, and can be heated and dried after the treatment. The drying temperature is, for example, 100 to 150 ° C, preferably 120 to 150 ° C, more preferably 140 to 150 ° C (preferably 145 to 150 ° C). By drying at a high temperature in this range, the elasticity of the high elastic fiber can be further improved.

The ratio of the high elastic fibers may be 50% by mass or more, for example, 50 to 100% by mass, preferably 60 to 100% by mass, more preferably 65 to 100% by mass (especially 70 to 100% by mass), based on the entire nonwoven fabric. about. The ratio of the high elastic fibers to the entire nonwoven fabric may be, for example, 50 to 90, from the viewpoints of excellent liquid retention, thickness reduction for compression, and rapid liquid resorption, and excellent balance between liquid retention and liquid resorption. The mass% is preferably from 55 to 85% by mass, more preferably from 60 to 80% by mass (preferably from 65 to 75% by mass). When the ratio of the high elastic fibers is too small, the elasticity of the nonwoven fabric cannot be improved.

(other fibers)

The non-woven fabric may contain other fibers (low elastic fibers) in addition to the aforementioned high elastic fibers in the range of not impairing the rigidity and the yarn return. Other fibers are preferably cellulose based on the viewpoint of improving liquid absorbency and liquid retention. fiber.

The cellulose fiber may be a natural fiber (wood pulp, cotton or cotton, hemp, etc.), but recycled fiber is preferable from the viewpoint of workability and the like. The regenerated fiber is exemplified by a regenerated cellulose fiber obtained by a viscose method (rayon, polynosic, etc.), and a regenerated cellulose fiber obtained by a copper ammonia method (copper ammonia fiber (eupra) A solvent-spun cellulose fiber (a lyocell such as TENCEL (registered trademark)) obtained by a solvent spinning method (a direct method in which the cellulose is temporarily subjected to chemical conversion). These cellulose-based fibers may be used singly or in combination of two or more.

Among these cellulose-based fibers, it is preferred to use a solvent-spun cellulose-based fiber from the viewpoint of excellent skin contact properties and excellent fiber strength in a wet state. Further, the solvent-spun cellulose-based fiber may be a cellulose system produced by a method in which a spinning dope in which cellulose is dissolved in an amine oxide is subjected to dry-wet spinning in water to precipitate cellulose and then extended. fiber. A representative example of such a solvent-spun cellulose-based fiber is exemplified by a soluble fiber, which is sold under the trade name "TENCEL" (registered trademark) by the Australian company LENZING.

The solvent-spun cellulose-based fiber is usually a fiber which is monofilamentized by defibration such as a heater, a refiner, or a high-speed dissociation machine. However, in the present invention, in order to prevent the microfiber from adhering to the fiber by monofilamentation, On the skin, it is preferably a solvent-spun cellulose fiber which is not monofilamentized.

Other fibers, like highly elastic fibers, may also contain conventional additives.

The Young's modulus of other fibers is less than 30 cN/T, for example, 1 to 29 cN/T, preferably 5 to 25 cN/T, more preferably 10 to 23 cN/T (especially 15 to 20 cN/T).

The cross-sectional shape of the other fibers may be a shape exemplified in the high elastic fiber item. However, from the viewpoint of excellent skin contact properties, the solvent-spun cellulose fiber has a circular cross section and an elliptical cross section.

The average fineness of the other fibers (especially cellulose fibers) is, for example, 0.3 to 5 dtex, preferably 0.5 to 2 dtex, more preferably 0.6 to 1.7 dtex (especially 0.8 to 1.5 dtex). When the other fibers are too coarse, the skin contact property is lowered, and the liquid absorbability or the liquid retainability is liable to be lowered. On the other hand, when it is too fine, the density of the non-woven fabric becomes high, and the inter-fiber voids are reduced, so that the liquid retainability is lowered.

The fiber length (average fiber length) of the other fibers is not particularly limited, and is, for example, 20 to 70 mm, preferably 30 to 60 mm, more preferably 35 to 50 mm. When the fiber length is too long, the fibers are difficult to uniformly entangle each other, the skin contact property is lowered, and the liquid absorbency and liquid release property are lowered. On the other hand, when the fiber length is too short, the fibers are liable to fall off from the nonwoven fabric, and the flexibility or stretchability is also lowered.

The ratio of high elastic fibers to other fibers (especially cellulose fibers) (mass ratio), especially for the excellent balance between liquid retention and liquid suckback, with high elastic fibers/other fibers (especially solvents) The spun cellulose fiber) = 60/40 to 80/20 is preferably more preferably 65/35 to 75/25. When the ratio of the high elastic fibers is too small, the elasticity of the non-woven fabric is lowered, and when the amount is too large, the effect of blending other fibers is lowered, for example, the ratio of the cellulose fibers. When it is small, liquid retention or liquid absorption cannot be improved.

In the present invention, the total ratio of the high elastic fibers and the cellulose fibers may be 50% by mass or more, for example, 80 to 100% by mass, preferably 90 to 100% by mass, more preferably 95 to 100% by mass based on the entire nonwoven fabric. About %, it is also possible to form a non-woven fabric only with high elastic fibers and cellulose fibers. In particular, when the liquid-retaining sheet of the present invention is used for contact with the skin, unlike the industrial water-absorbent sheet which requires dimensional stability, etc., the content of the conventional binder fiber which lowers the skin contact property is less preferable. For example, the ratio of the binder fibers may be 10% by mass or less, preferably 5% by mass or less, and more preferably 1% by mass or less based on the entire nonwoven fabric.

[Method of manufacturing non-woven fabric]

The non-woven fabric (liquid holding sheet) can be produced by, for example, a spunlace method, a needle punch method, a steam jet method, or the like. Among these methods, water flow cytometry is preferable in terms of simplicity and the like.

The spunlace method can also produce a non-woven fabric by, for example, a carding machine to open a staple fiber, such as a high elastic fiber (or a mixture of high elastic fibers and other fibers), with a carding machine. The non-woven fabric may be a plain woven fabric arranged in a direction in which the fibers of the fabric are arranged in the direction of travel of the card, a weft fabric obtained by raising the weft of the plain woven fabric, a randomly arranged random fabric, or a plain woven fabric and Any one of the semi-random grey fabrics arranged in the middle of the fabric, but the fabric is prevented from being stretched in the transverse direction as compared with the fiber in the transverse direction, so that the conformability to the skin during use is lowered. Plain grey fabrics or weft grey fabrics, plain woven fabrics, and random grey fabrics ensure The laminated sheet is preferably soft in the transverse direction and extensible.

Further, the spunlace method performs a water flow complexing treatment on the obtained non-woven fabric. The water flow complexing treatment system is, for example, a nozzle disk having a diameter of 0.05 to 0.3 mm (especially 0.08 to 0.2 mm) at intervals of 0.3 to 1.5 mm (especially 0.4 to 1 mm) at intervals of 1 to 3 rows (especially 1 to 2 rows). The jetted water collides with the non-woven fabric placed on the porous support member, and the fibers constituting the nonwoven fabric are three-dimensionally interconnected and integrated. When performing three-dimensional entanglement on the non-woven fabric, it is preferred to place the non-woven fabric on the moving porous support member, for example, water flow treatment of 1 to 15 MPa, preferably 2 to 12 MPa, and more preferably 3 to 10 MPa. Method of multiple or multiple times. Preferably, the injection holes are arranged in a line in a direction orthogonal to the traveling direction of the nonwoven fabric, and the nozzle disk in which the ejection holes are arranged is oriented at right angles to the traveling direction of the nonwoven fabric placed on the porous supporting member. The water oscillating at the same interval from the injection hole uniformly collides with the non-woven fabric. The porous support member on which the nonwoven fabric is placed is, for example, a mesh or a perforated plate of a metal mesh or the like, and is not particularly limited as long as water can flow through the nonwoven fabric. The distance between the injection hole and the non-woven fabric can be selected according to the water pressure, for example, about 1 to 10 cm. When it is outside this range, the texture of the non-woven fabric is easily disordered, and the three-dimensional entanglement is insufficient.

Drying treatment may also be carried out after the water flow complexing treatment. As the drying treatment, it is preferred to first remove excess water from the non-woven fabric after the treatment, and a conventional method can be used for the removal of excess moisture. For example, the excess moisture may be removed to some extent by using a twisting device of a mangle roller, and then a drying device such as a hot air circulation dryer using an air suction belt method may be used. Except for residual moisture.

[Liquid holding sheet]

The liquid-retaining sheet of the present invention may be a sheet in which a liquid component is impregnated into a nonwoven fabric, for example, a liquid-based component containing a cosmetic (cosmetic liquid) is impregnated with a non-woven fabric sheet (especially a mask).

The liquid-retaining sheet of the present invention can also be used for the purpose of absorbing a liquid component, for example, a body fluid absorbing sheet (or skin wash) for a surface material such as a sanitary napkin or a diaper, a diaper lining, a wet tissue, or the like. Although it is excellent in the balance of liquid retention property and release property, it can be easily adhered to the skin, and therefore it is preferably used for adhering a sheet containing a liquid component such as a cosmetic component or a medicinal component. For skin applications, such as masks, make-up sheets or cleansing sheets, body cleansing sheets (sweat sheets, oil absorbing sheets, etc.), cooling sheets, medicinal or therapeutic sheets (inhibiting itching sheets, wet cloth, etc.) The skin care sheet is particularly preferably used for a mask because it is quickly sucked back by a finger pressing liquid component.

The liquid-retaining sheet of the present invention may be a sheet which is used by impregnating the liquid components at the time of use, or may be a sheet (so-called wet sheet) which is used by impregnating the liquid component in advance.

In the present invention, the liquid component is contained in a liquid material such as a solvent or a liquid oil, and a solution or dispersion (cosmetic or emulsion) containing an active ingredient such as a cosmetic component or a pharmacological (potency) component in the liquid material. Wait). The solvent may be a lipophilic solvent, but is preferably a hydrophilic solvent based on aspects such as safety to human body. The hydrophilic solvent is exemplified by, for example, water, a lower aliphatic alcohol (e.g., a C _1-4 alkanol such as ethanol or isopropyl alcohol), an alkanediol (e.g., ethylene glycol, diethylene glycol, propylene glycol, etc.). These hydrophilic solvents may be used singly or in combination of two or more. Examples of the liquid oil are, for example, unsaturated higher fatty acids (e.g., oleic acid, oleyl alcohol, etc.), animal and plant oils (e.g., jojoba oil, olive oil, coconut oil, eucalyptus oil, macadamia nut oil, crocodile Pear oil, corn oil, sesame oil, wheat germ oil, linseed oil, flax oil, squalane, etc.), mineral oil (such as liquid paraffin, with butene, helium oxide, etc.), synthetic oil (such as synthetic ester oil) , synthetic polyether oil, etc.). These liquid oils may be used singly or in combination of two or more.

These liquid substances may be used singly or in combination of two or more. For example, it can be used as a liquid oil as an additive (oil) in combination with a hydrophilic solvent such as water or ethanol. Among these liquid materials, water, a lower alcohol or a mixture of these are usually used, and water and/or ethanol (especially water) is preferably used. For example, when combined with water and a lower alcohol (especially ethanol), the ratio (volume ratio) of the two is water/lower alcohol = 100/0 to 30/70, preferably 100/0 to 50/50, more It is preferably around 100/0~70/30, for example, it can be around 99/1~80/20.

As the active ingredient, for example, a conventional additive such as a physiologically active ingredient (skin softener, whitening agent, sweating agent, skin roughness preventing agent, anti-inflammatory agent, skin itching inhibitor, blood circulation promoting agent, cell activator, etc.), moisturizing Agents, softeners, detergents, ultraviolet absorbers, surfactants, astringents, enzymes, cooling agents, bactericides or antibacterial agents, antioxidants, amino acids, coolants, perfumes, colorants, and the like. Such The additives may be used singly or in combination of two or more. Among these additives, for example, a moisturizing agent, an ultraviolet absorber, a surfactant, a cooling agent, an aldehyde, an astringent, a bactericide, or an antibacterial agent are widely used for the skin care sheet. In particular, in the mask (face), for example, a humectant or a softener or the like may be formulated in a hydrophilic solvent. Examples of the humectant or softener are, for example, dipropylene glycol, 1,3-propanediol, polyethylene glycol, polyoxyethylene-polyoxypropylene block copolymer, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sucrose fat. Acid ester, glycerin, sodium hyaluronate, polyoxymethylglycoside, polyvinyl alcohol, polyvinylpyrrolidone, water-soluble cellulose ester (methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl Methylcellulose, hydroxypropylmethylcellulose, etc.). The total ratio of the humectant and the softener is, for example, 0.1 to 50% by mass in the solution, preferably 1 to 30% by mass, more preferably 5 to 20% by mass.

The ratio of the additives may be appropriately selected depending on the use, and the ratio of the liquid substance such as water or ethanol is usually 30 to 99% by mass, preferably 40 to 95% by mass, more preferably in the total liquid component containing the additive. 50~90% by mass.

Since the liquid-retaining sheet of the present invention is excellent in adhesion to the skin, it is particularly suitable as a sheet to be fixed to the skin such as a mask or a damp cloth. For example, since the portion which is not swelled and which is swelled can be easily corrected, the fine gap (concave-convex) sheet such as the root of the nose can be adhered, and the active ingredient of the mask can be effectively permeated to the skin.

The liquid retaining sheet of the present invention is also suitable for use in cleaning sheets or skin cleaning sheets and the like. That is, the liquid retaining sheet of the present invention is The fine gap sheet of the face can also be adhered to, so that the makeup can be effectively removed (foundry, powder, lipstick, eye makeup, etc.).

When the liquid-retaining sheet of the present invention is used as a liquid-impregnated biofilm sheet (such as a mask), the liquid component is usually impregnated into the liquid-retaining sheet, and attached or contacted with the skin of the living body or the like.

The liquid-retaining sheet of the present invention may be laminated with other layers, for example, in order to promote absorption of the active ingredient, or to laminate a non-porous film or sheet on the side not in contact with the skin.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is by no means limited to the following examples. Moreover, each physical property value in the following examples and comparative examples was measured or evaluated by the following method. Further, the details of the fibers used in the following examples and comparative examples are as follows.

[Fused Viscosity (Pa.s)]

After preheating at 290 ° C for 10 minutes using a melt viscosity meter, the molten thermoplastic resin was extruded from the nozzle and measured.

[MI (melt index) (g/10 minutes)]

A certain amount of synthetic resin (2160 g) was heated/pressurized to a predetermined temperature (190 ° C) in a cylindrical vessel heated by a heater, and the opening (nozzle) provided from the bottom of the vessel was measured to be extruded every 10 minutes. The amount of resin.

[Fiber fineness (dtex)]

Five sets of 30 pieces of monofilament cut into 30 mm were prepared, and the weight of each sample was measured, and each measurement was performed twice.

Denier (dtex) = weight (g) / (number of strips 30 × fiber length 30 mm) × 1000 m.

[Unit weight (g/m ² )]

According to JIS L1906, the sample was allowed to stand in a standard state of a temperature of 20 ° C and a humidity of 65% for 24 hours, and then a sample having a width of 1 m × a length of 1 m was taken, and the weight (g) was measured using a balance. The weight (g) of the obtained weight is rounded off to the unit area weight.

[thickness (mm)]

The sample was cut in the MD direction perpendicular to the surface using a razor (FEATHER Razor, S-blade). The microscope was observed with a digital microscope "DIGITAL MICROSCOPE VHX-900". Sample profile and thickness measurement.

[Compression elasticity in the thickness direction when the beauty liquid is impregnated (compression elasticity during impregnation) (%)]

Prepare a sample cut into 5 cm in the MD direction and 5 cm in the CD direction, and impregnate the beauty liquid ("FRESHEL ESSENCE LOTION NA" manufactured by Kanebo Cosmetics Co., Ltd.) with a sample weight of 900%. As shown in Fig. 1, the sample 3 is prepared. The flatness was allowed to stand on the acrylic plate (measuring table) 4, and the initial thickness was measured by a laser displacement meter 1. Next, a load of 260 g/cm ^{2 was} applied to the center of the grey fabric (non-woven fabric) for 60 seconds, and the displacement immediately after the load was removed to 300 seconds was measured. The thickness of the grey fabric before the measurement is set to A, the thickness immediately after the load is removed is B, and when the load is 300 seconds after the load is removed, the compression elasticity in the thickness direction when the cosmetic liquid is impregnated is determined according to the following formula ( %).

Compression elasticity in the thickness direction when the cosmetic liquid is impregnated (%) = [(C-B) / (A-B)] × 100

[Water retention rate (%)]

The measurement was carried out in accordance with JIS L1907 7.2 water absorption rate. The test piece was cut into 5 cm squares, and the weight (Ag) was measured. The test piece was immersed in water for 30 seconds. After the immersion, the test piece was pinched with a clip and taken out from the liquid, and the weight (Bg) after 1 minute was measured. The liquid retention ratio (C%) was calculated from the following formula.

C(%)=[(B-A)/A]×100

[Returning liquid to the grey fabric (%)]

Prepare a sample cut into 5 cm in the MD direction and 5 cm in the CD direction, and impregnate the beauty liquid ("FRESHEL ESSENCE LOTION NA" manufactured by Kanebo Cosmetics Co., Ltd.) of 900% of the sample weight, as shown in Fig. 2, and sample 13 The flat plate was placed on an acrylic plate (measuring table) 14 and placed at a central portion of a circular shape having a diameter of 1.2 cm by applying a load of 620 g for 12 seconds, and the width of the beauty liquid was not measured immediately after the load was removed. Further, it was measured that there was no partial width of the cosmetic liquid after the load was removed for 300 seconds. No beauty liquid will be removed after the load is removed The partial width was set to A, and when the partial width of the non-cosmetic liquid was set to B after the load was removed for 300 seconds, the liquid suckback (%) to the grey fabric was determined according to the following formula.

Liquid resorption of the grey cloth (%) = [(A-B) / A] × 100

[30% elongation stress (N/5cm) when wet]

The measurement was carried out in accordance with the method described in JIS L1913 (general short fiber nonwoven fabric) 6.3.2 (tensile strength and elongation test at wetness). Specifically, the sample was placed in water at 20 ° C ± 2 ° C by self-weight sedimentation, or was submerged in water for 1 hour or more, and then taken out from the immersion liquid and the stress (wet stress) at 30% elongation was measured as soon as possible.

[Manufacturing method of core-sheath composite fiber]

(core sheath composite fiber A)

An ethylene-vinyl alcohol copolymer ("EVAL" manufactured by KURARAY Co., Ltd.) having an ethylene content of 44 mol% and an MI value of 12 g/10 min was used as the sheath component, and the melt viscosity at 290 ° C was 12,000 [Pa. s] polyester sheet (polyethylene terephthalate, KURARAY (stock), intrinsic viscosity = 0.61) as a core component, using a composite melt spinning device, at a temperature of 290 ° C, with a circular profile metal The core was joined and spun with a core-sheath type at a composite ratio (core/sheath) = 50/50 (weight ratio). After the spun yarn was cooled and solidified, it was taken up on a shuttle shaft at a speed of 1000 m/min by a pulling roll to obtain a 5.3 dtex take-up wire. Next, the wound wire was subjected to heat elongation at a stretching temperature of 90 ° C at a stretching ratio of 2.8 times, and an oil agent was applied in an oil bath, followed by mechanical crimping treatment. Mechanical crimping treatment system uses the usual stuffing type crimping The device is given. After the crimping treatment, the fibers were dried by hot air at 150 ° C, and then cut into 51 mm to obtain short fibers having a single yarn fineness of 1.9 dtex, a crimping number of 23/25 mm, and a Young's modulus of 51.0 cN/T (core sheath composite). Fiber A). Both spinnability and elongation are good.

(core sheath composite fiber B)

In the same manner as in the production method of the core-sheath composite fiber A, the single-filament fineness was 1.9 dtex, the fiber length was 51 mm, and the number of crimps was 23/25 mm, and Yang was obtained, except that the stretching ratio was 2.4 times and the drying temperature of the hot air was 150°C. Core-sheath composite fiber B having a modulus of 40.1 cN/T.

(core sheath composite fiber C)

In the same manner as in the production method of the core-sheath composite fiber A1, the single-filament fineness was 1.9 dtex, the fiber length was 51 mm, and the number of crimps was 23/25 mm, and Yang was obtained, except that the stretching ratio was 2.5 times and the drying temperature of the hot air was 140°C. Core-sheath composite fiber C with a modulus of 30.8 cN/T.

(core sheath composite fiber D)

In the same manner as in the production method of the core-sheath composite fiber A, the single-filament fineness was 1.9 dtex, the fiber length was 51 mm, and the number of crimps was 23/25 mm, and Yang was obtained, except that the stretching ratio was 2.3 times and the drying temperature of the hot air was 140°C. Core-sheath composite fiber D with a modulus of 23.3 cN/T.

[Used fiber]

TENCEL fiber: "TENCEL" manufactured by LENZING, with a fineness of 1.7 dtex, an average fiber length of 38 mm, and a Young's modulus of 19.2 cN/T

缧萦 fiber: OHIKENSHI (share) "HOPE", fineness 1.7dtex, average fiber length 38mm, Young's modulus 13.3cN/T

Polyphenylene sulfide (PPS) fiber: "PROCON" manufactured by Toyobo Co., Ltd., 2.2dtex, Young's modulus 441.0cN/T

PET fiber: TORAY (stock), fineness 1.7dtex, average fiber length 51mm, Young's modulus 29.8cN/T

Mian fiber: Pill industry (stock) system, fineness 1.6dtex, Young's modulus 12.8cN/T.

Examples 1 to 7 and Comparative Examples 1 to 4

The fibers shown in Table 1 were mixed (unmixed when a single fiber was used) to produce a carded fabric. Next, the card blank was sprayed with a water stream, and a complexing treatment was applied to obtain a water flow complex nonwoven fabric. Further, the water flow complexing treatment was carried out by using a nozzle having a diameter of 0.1 mm at intervals of 0.6 mm in the width direction of the fabric, and spraying and entanglement at every two stages of the front and back with a water pressure of 3 to 5 MPa.

The evaluation results of the nonwoven fabric obtained in the examples and the comparative examples are shown in Table 1.

As is apparent from the results of Table 1, the water-repellent rate of the non-woven fabric of the examples was high, and the compression elasticity in the thickness direction (compression elasticity during impregnation) and the suckback were all fast when the beauty liquid was impregnated, whereas the non-woven fabric of the comparative example was impregnated. Compressive elasticity and slow suction. In particular, in the comparative example, regardless of the ratio of the compressive elasticity at the time of impregnation, the liquid back-feeding of the grey fabric is as low as about 50%, and in contrast, in the embodiment, the liquid back of the fabric is sucked back. The nonwoven fabric which is increased in proportion to the compressive elasticity at the time of impregnation, and particularly contains 70% by mass or more of the core-sheath composite fiber A having a high Young's modulus, exhibits a higher liquid back-feeding of the fabric of more than 80%.

Reference example 1~12

In order to make the relationship between the compression elasticity and the liquid suckback in the impregnation of Comparative Examples 1 to 4 clearer, the fibers shown in Table 2 were mixed (unmixed when a single fiber was used), and Examples 1 to 5 and Comparative Examples. 1~4 has the same modulation Non-woven fabrics with various compressive elastic ratios during impregnation. Further, Comparative Examples 1 to 4 are Reference Examples 6, 1, 2, and 10, respectively.

As shown in the results of Table 2, the non-woven fabric of the reference example, although the compressive modulus of elasticity during the impregnation is wide from 3.6% to 56.7%, the liquid back-feeding of the grey fabric is still at a low level of about 40 to 50%. . This tendency indicates that it is difficult to control the liquid suckback rate within a specific range during impregnation.

On the other hand, as is apparent from the results of Table 1, in the examples, the compression modulus at the time of impregnation exceeds 60%, and the impregnation compressive elasticity is improved, and the liquid backlash of the fabric is also improved, and the compression modulus at impregnation exceeds 75. At %, the liquid backlash of the grey fabric is also more than 80%.

That is, as is apparent from the results of Tables 1 and 2, in the present invention, by forming a non-woven fabric with a high proportion of elastic fibers in a specific ratio, the compression elasticity at the time of impregnation is adjusted to a specific reset or more, and the first successful production of the nonwoven fabric is achieved. The liquid resorption is drastically improved, and the effect of such an embodiment is a remarkable effect unpredictable by conventional non-woven fabrics containing low elastic fibers.

[Industrial availability]

The liquid holding sheet of the present invention can be utilized for the purpose of absorbing a liquid component and contacting the skin, such as a sheet for liquid absorption (such as a surface material such as a sanitary napkin or a diaper, a diaper lining, a wet tissue, etc.), a skin care sheet (for example). Mask, makeup remover, cleansing sheet or body cleansing sheet (sweat sheet, oil absorbing sheet, cooling sheet, etc.), medicinal sheet (inhibiting itching sheet, wet cloth, etc.). In particular, the liquid-retaining sheet of the present invention is in a state of impregnating a liquid component such as a cosmetic liquid (cosmetic material), and even if it is pressed by a finger, the sucking of the liquid component is rapid, so that it can be used for the entire face, nose, eyes, mouth corner, A mask for impregnating and whitening equivalent components of the neck and the like.

Claims (9)

A skin care sheet formed of a non-woven fabric containing 50% by mass or more of a high elastic fiber having a Young's modulus of 30 to 500 cN/T, wherein the high elastic fiber is a core-sheath type composite fiber and impregnated with a liquid component. The skin care sheet of claim 1, wherein the sheath portion of the core-sheath type composite fiber is formed of an ethylene-vinyl alcohol copolymer, and the core is formed of a hydrophobic resin. A skin care sheet according to claim 2, wherein the hydrophobic resin is a polyester resin. The skin care sheet according to any one of claims 1 to 3, wherein the high elastic fiber has an average fineness of 1.5 to 10 dtex. The skin care sheet according to any one of claims 1 to 3, wherein the high elastic fiber is a fiber obtained by stretching 2.0 times or more at a temperature of 80 ° C or higher. The skin care sheet according to any one of claims 1 to 3, further comprising a cellulose fiber having an average fineness of 0.3 to 5 dtex, and a mass ratio of the high elastic fiber to the cellulose fiber is a high elastic fiber/cellulose fiber = 60/40~80/20. The skin care sheet according to any one of claims 1 to 3, which is impregnated with a skin care sheet containing a liquid component of the cosmetic. A skin care sheet according to any one of claims 1 to 3, which is a mask. The skin care sheet according to any one of claims 1 to 3, wherein the skin is immersed in a beauty liquid having a weight of 900% by mass and is loaded with a load of 260 g/cm ² for 1 minute and then removed, and the reduction of the compression in the thickness direction is 60% or more in 5 minutes.