TWI793244B - Water-absorbing fiber precursor, water-absorbing nonwoven fabric precursor and water-absorbing nonwoven fabric; as well as facial mask containing the same and face mask having lotion already filled with, and their manufacturing method - Google Patents

Abstract

Among face masks containing a lotion and others, the nonwoven fabric containing a water absorbing fiber is used in order to make it good in liquid retention and a feeling of wearing. Such a non-woven fabric is produced mainly by thermal bonding processing. However, it is little entanglement of fibers and after wearing, fluff tends to be easily remained on the skin. As to reduction of the plush, the spinning lace processing is effective, however, it is difficult to be applied to the water absorbing and swelling water-absorbing fiber. The present invention provides a spun lace processed water-absorbent nonwoven fabric. A water-absorbing fiber precursor which is characterized in comprising 0.1 to 5.0 mmol/g of an H-type carboxyl group and less than 0.5 mmol/g of a salt-type carboxyl group, in which the total amount of the H-type carboxyl group and the amount of the salt-type carboxyl group is 0.5 mmol/g or more, the water absorption rate is 10 to 1000% by mass, and a water absorption rate is 500 to 50000% by mass when the neutralization degree of the carboxyl group is adjusted to 50%.

Description

Water-absorbent fiber precursor, water-absorbent non-woven fabric precursor, water-absorbent non-woven fabric, facial mask containing the same, facial mask filled with lotion, and their manufacturing methods

The present invention relates to a water-absorbent fiber precursor, water-absorbent non-woven fabric precursor, water-absorbent non-woven fabric, and their manufacturing methods. In addition, the present invention also relates to a facial mask containing the aforementioned water-absorbent nonwoven fabric precursor or the aforementioned water-absorbent nonwoven fabric, and a facial mask filled with lotion.

Conventionally, it has been known to use woven fabrics containing water-absorbent fibers in order to improve liquid retention and improve the feeling of use when using a mask that contains active ingredients such as lotion for skin care. Therefore, since water-absorbent fibers swell due to water absorption, it is difficult to obtain nonwoven fabrics by spun lace processing that entangles them with water flow. Therefore, a method of producing a nonwoven fabric in combination with a thermal bonding process of thermally fusing fibers has been employed.

For example, Patent Document 1 discloses a water-absorbent non-woven fiber product comprising acrylic fibers (A) and at least a part of the surface of the fibers is a heat-adhesive product composed of a polymer component with a melting point of 200°C or lower. The composite fiber (B) is formed as the main component; and at least a part of the outer layer of the fiber (A) of the non-woven fiber product provided with a thermally fused junction is introduced with a cross-linking bond and 0.1 mmol/g or more - COOX (X: alkali metal or NH ₄ ) made of basic carboxyl groups has a water swelling degree of 2 cc/g or more of the product.

Also, Patent Document 2 discloses a shaped absorbent body for sanitary materials, which is composed of 10 to 80% by mass of superabsorbent fibers with a water swelling degree of 10 times or more, and 90 to 20% by mass of hot-melt adhesive formed by fibers.

In addition, Patent Document 3 discloses a method of using a sheet-shaped packaging material, which is characterized in that: the core part is formed of polyacrylonitrile, the sheath part is made of polyacrylate core-sheath fiber and adhesive The non-woven fabric formed of fibers is used as the base material; the thickness of the base material is 0.01-1 mm when dry, and the density is 0.01-2.0 g/m ³ , and it is packaged in a sheet form that is liquid-permeable even in a wet state material, impregnating the sheet-shaped package with the active ingredient-containing liquid, attaching the sheet-shaped packaging material to the skin surface, and performing massage in the pasted state, thereby promoting the flow of the active ingredient-containing liquid in the sheet-shaped packaging material Fitting side releases. "Prior Art Documents""PatentDocuments"

"Patent Document 1" JP-A-57-21549 Gazette "Patent Document 2" JP-11-200209 Gazette "Patent Document 3" Japanese Unexamined Publication No. 2006-169173

"Problem to be Solved by the Invention"

However, the technologies of Patent Documents 1 to 3 are all to use a kind of heat-adhesive fiber and water-absorbent fiber to form a carding web after blending, and to melt the heat-adhesive fiber by heating or a hot roller. Thermal bonding processing for joining with water-absorbent fibers. In terms of joints joined by thermal adhesive fibers, it is difficult to cause fuzz by joining the fibers to each other. In other cases, there is little intertwining between fibers, and fluff is unavoidably easy to be generated. Therefore, when the nonwoven fabric processed by thermal bonding is used for a face mask, for example, there is a so-called problem of poor wearing feeling due to fluff rising up.

Regarding this point, if spinning lace processing can be used, it will have sufficient strength because the fibers are entangled with each other by water flow, and it is also possible to produce a non-woven fabric that is difficult to produce fluff. However, for the above-mentioned water absorption As far as fiber is concerned, it is difficult to adopt this kind of processing method.

The present invention was created in view of the current state of the conventional technology, and its object is to provide a water-absorbent nonwoven fabric precursor and a water-absorbent nonwoven fabric that contain less fluff and excellent wearing feeling when used in facial masks, etc. The facial mask and facial mask filled with lotion, and their manufacturing methods. "Means to Solve Problems"

As a result of earnest research by the present inventors to achieve the above object, it has been found that if the amount of basic carboxyl groups in the water-absorbent fiber decreases and the amount of H-type carboxyl groups increases to inhibit the water absorption performance, spinning and lace processing can be performed. . In addition, it was also found that after spinning lace processing, the compound that generates cations acts and increases the amount of basic carboxyl groups, so that the nonwoven fabric can have water absorption, become softer, and have less fluff, and become a popular fabric. Sensitive excellent thing, so far the present invention has been completed.

That is, the present invention can be achieved by the following means. (1) A water-absorbent fiber precursor, characterized by: having 0.1 to 5.0 mmol/g of H-type carboxyl groups and less than 0.5 mmol/g of basic-type carboxyl groups; the amount of the aforementioned H-type carboxyl groups and the aforementioned amount of basic-type carboxyl groups The total amount is 0.5 mmol/g or more; the water absorption is 10 to 1,000% by mass; and the water absorption is 500 to 50,000% by mass when the degree of neutralization of the carboxyl group is adjusted to 50%. (2) The water-absorbent fiber precursor described in (1), which has a core-sheath structure. (3) The water-absorbent fiber precursor described in (1) or (2), which has a cross-linked structure. (4) A water-absorbent nonwoven fabric precursor, characterized in that it contains the water-absorbent fiber precursor according to any one of (1) to (3), and has a spun lace structure. (5) The water-absorbent nonwoven fabric precursor described in (4), wherein the number of piles is 10 or less in the evaluation method described below. (Evaluation method) Within the range of a square of 10 cm on one side, the end is protruding from the surface of the nonwoven fabric, and the number of piles with a length of 3 mm or more is visually measured. The same measurement is also carried out at other arbitrary 2 places, and the average value of the measurement results of all 3 places is used as the number of plush. (6) The water-absorbent nonwoven fabric precursor described in (4) or (5), wherein the content of the water-absorbent fiber precursor is 10 to 100%. (7) A water-absorbent nonwoven fabric comprising water-absorbent fibers having 0.5 to 5.5 mmol/g of basic carboxyl groups, a water absorption rate of 500 to 20,000% by mass, and a spun lace structure. (8) The water-absorbent nonwoven fabric described in (7), wherein the water-absorbent fiber content is 10 to 100%. (9) The water-absorbent nonwoven fabric described in (7) or (8), wherein the water-absorbent fibers have a core-sheath structure. (10) The water-absorbent nonwoven fabric described in any one of (7) to (9), wherein the water-absorbent fibers have a cross-linked structure. (11) A facial mask, characterized in that it has the water-absorbing non-woven fabric precursor as described in any one of (4) to (6), or the water absorption as described in any one of (7) to (10) Non-woven. (12) A facial mask filled with lotion, characterized in that the lotion is filled in the mask as described in (11). (13) A method for producing a water-absorbent nonwoven fabric precursor, characterized by interlacing a carding web containing the water-absorbent fiber precursor in any one of (1) to (3) by the spinning lace method the steps. (14) A method for producing a water-absorbent nonwoven fabric, comprising the steps of interlacing a carding web containing the water-absorbent fiber precursor according to any one of (1) to (3) by a spinning lace method, and a step of converting at least a part of the aforementioned H-type carboxyl groups into basic-type carboxyl groups by acting on the water-absorbent nonwoven fabric precursor obtained through the step with a compound generating a cation. "Invention Effect"

The water-absorbent non-woven fabric precursor and the water-absorbent non-woven fabric of the present invention are obtained by spinning lace, so they have the so-called characteristics of soft non-woven fabric and less fluff. The water-absorbent nonwoven fabric precursor and the water-absorbent nonwoven fabric of the present invention having such characteristics can be used as, for example, facial masks or wound dressing materials.

The water-absorbent fiber precursor of the present invention is one having 0.1-5.0 mmol/g of H-type carboxyl groups. In the case where the amount of H-type carboxyl groups is less than 0.1 mmol/g, after forming the water-absorbent nonwoven fabric precursor, even if a compound that generates a cation described later acts, it may cause a problem that a water-absorbent nonwoven fabric that exhibits a sufficient water absorption capacity cannot be obtained. Doubt will also be heightened. On the contrary, when it exceeds 5.0 mmol/g, since the amount of water absorption becomes excessively large, it will cause so-called unsuitability that it becomes difficult to form a nonwoven fabric by the spinning lace method. The amount of such H-type carboxyl groups is preferably 0.5-4.0 mmol/g; more preferably 1.0-3.5 mmol/g.

Also, the water-absorbent fiber precursor of the present invention is one having a basic carboxyl group of less than 0.5 mmol/g. Compared with the H-type carboxyl group, the basic carboxyl group has a particularly high hydrophilicity, so when it is more than 0.5 mmol/g, when the non-woven fabric is processed by the spinning lace method, gelation will be formed due to excessive water absorption. As a result, the so-called unsuitable situation in which the intertwining of fibers or drying becomes difficult will occur. The amount of such basic carboxyl groups is preferably below 0.4 mmol/g; more preferably below 0.3 mmol/g. In addition, it may not have a basic carboxyl group at all.

In addition, the total amount of the aforementioned H-type carboxyl groups and base-type carboxyl groups is at least 0.5 mmol/g; preferably at least 0.6 mmol/g; more preferably at least 0.7 mmol/g. If it is less than 0.5 mmol/g, after forming the water-absorbent nonwoven fabric precursor, even if the cation-generating compound described later is activated, there may be a so-called problem that a water-absorbent nonwoven fabric exhibiting a sufficient water absorption capacity cannot be obtained. will also be high. In addition, it can be understood from the above-mentioned ranges of the amount of H-type carboxyl groups and the amount of base-type carboxyl groups that the total amount is preferably 5.5 mmol/g.

Also, the water-absorbent fiber precursor of the present invention is one having a water absorption rate of 10 to 1000% by mass. When the water absorption is less than 10% by mass, there is no sufficient water absorption when the water-absorbent fiber is converted by a method such as will be described later. Also, if it exceeds 1000% by mass, water will be absorbed excessively when the nonwoven fabric is processed by the spun lace method, so that so-called inappropriate conditions such as entanglement of fibers and difficulty in drying will occur. Such water absorption is preferably from 12 to 700% by mass, more preferably from 15 to 500% by mass.

Moreover, the water-absorbent fiber precursor of the present invention is characterized in that its water absorption is 500 to 50000% by mass when the degree of neutralization of the carboxyl group is adjusted to 50%. Therefore, in the present invention, adjusting the degree of neutralization of carboxyl groups to 50% means that among the carboxyl groups contained in the water-absorbent fiber precursor, 50 mol% of sodium salt-type carboxyl groups and the rest as H Type carboxyl. When the water absorption at a neutralization degree of 50% is less than 500% by mass, there may be a high concern that a water-absorbent nonwoven fabric capable of exhibiting sufficient water absorption cannot be obtained. Conversely, when it exceeds 20000% by mass, since the amount of water absorption increases excessively, it may be unsuitable to easily drop off from the mounting part when processed into a facial mask or the like described later. When the degree of neutralization is adjusted to 50%, the water absorption is preferably from 600 to 48,000% by mass; more preferably from 700 to 45,000% by mass.

In addition, as far as the water-absorbent fiber precursor of the present invention is concerned, its fineness is preferably 0.5-15.0 dtex. By making the fineness 0.5 dtex or more, sufficient strength can be ensured; it can also withstand the water flow during spinning and lace processing, so it is difficult to cause fiber cutting. On the other hand, if the fineness is 15.0 dtex or less, when the finally obtained water-absorbent nonwoven fabric touches the skin, it will hardly give stiff discomfort; Good adhesion.

In addition, as the water-absorbent fiber precursor of the present invention, the fiber length is preferably 10-200 mm. By setting the fiber length to 10 mm or more, the fibers are easily entangled with each other by the water flow during spinning and lace processing. On the other hand, if the fiber length is 200 mm or less, it can pass through a carding machine at the time of making a carding web. Such fiber length is preferably 15-170 mm; more preferably 20-150 mm.

A representative example of the aforementioned water-absorbent fiber precursor is a fiber having a core-sheath structure in which the core portion is an acrylic polymer and the sheath portion is an acrylic polymer having an H-type carboxyl group.

In such a fiber having a core-sheath structure, the carboxyl group of the acrylic polymer in the sheath part is in the H-type state, and since the water absorption performance is suppressed, spinning lace processing can be performed. Next, as will be described later, the compound that generates cations after spinning lace processing works, and by changing the H-type carboxyl group of the sheath part into a base-type carboxyl group, the performance of increasing water absorption and swelling can be exhibited. For example, as described later, When a lotion is provided, it becomes an active ingredient that can be stably maintained with sufficient moisture.

Also, the core part is an acrylonitrile polymer; since this polymer is of high mechanical strength, it can reinforce the fiber. Therefore, even if the strength of the sheath part decreases during water absorption, the fiber form can be maintained and the mechanical strength can be ensured.

In addition, as the water-absorbent fiber precursor of the present invention, it is preferable to have a cross-linked structure in order to more reliably maintain the fiber shape during water absorption and secure the mechanical strength.

Fibers having the above-mentioned core-sheath structure can be formed by subjecting the surface layer of fibers made of acrylonitrile-based polymers (hereinafter referred to as acrylonitrile-based fibers) to cross-linking treatment and hydrolysis treatment to generate carboxyl groups. Then, it is produced by performing an acid treatment and converting it into an H-type carboxyl group. Hereinafter, such a production method will be described in detail.

First, the acrylonitrile-based polymer constituting the acrylic fiber used as a raw material is desirably contained at least 80% by mass of acrylonitrile, preferably at least 85% by mass of the polymer. Copolymerizable monomers, for example, which may be vinyl halides and vinylidene halides such as vinyl chloride, vinyl bromide, vinylidene chloride, etc.; vinylic acid, methacrylic acid, maleic acid, itaconic acid, etc. Unsaturated carboxylic acids and their salts; (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate; vinyl acetate, propionic acid Vinyl esters such as vinyl esters; ethylenically unsaturated sulfonic acids such as vinylsulfonic acid, (meth)acrylsulfonic acid, p-styrenesulfonic acid, etc., and their salts; (meth)acrylyl Vinyl compounds such as amide, vinylidene cyanide, methacrylonitrile, etc. Using such a polymer, an acrylic fiber can be obtained by wet spinning or the like by a known method.

Next, an aqueous solution containing a hydrazine-based compound and a basic metal compound is attached to the acrylic fiber, and the cross-linking and hydrolysis of the hydrazine-based compound proceed simultaneously by heating.

Specifically, the amount of adhesion of the aqueous solution of the hydrazine compound and the basic metal compound to the dry mass of the aforementioned acrylic fiber is preferably adjusted to 1.0 to 20.0 meq/g for the basic metal compound, Preferably, it is 2.5-15.0 meq/g; for _{hydrazine -} based compounds, it is expected to be adjusted to 0.01-2.0% by mass, preferably 0.05-1.5% by mass. For the fiber, the fiber is heated at a temperature of 80°C or higher for 1 to 120 minutes, preferably in a humid atmosphere of 100 to 150°C for 5 to 40 minutes.

Therefore, when the amount of hydrazine attached to the dry fiber mass does not meet the above-mentioned lower limit, the gel strength of the obtained fiber having a core-sheath structure decreases when absorbing water, so the gel may fall off. possibility. On the other hand, when the upper limit is exceeded, the water absorption performance of the obtained fiber having a core-sheath structure may become insufficient.

Examples of the hydrazine compound used here include hydrazine in water, hydrazine sulfate, hydrazine hydrochloride, hydrazine nitrate, hydrazine bromate, and the like. Also, the so-called basic metal compound refers to a substance showing a pH of 7.5 or more when forming a 1.0% by mass aqueous solution; an example of such a substance, for example, it can be the hydrogen of alkali metals such as Na, K, Li, etc. Alkali metal salts of Na, K, Li, etc., oxides or organic acids such as carbonic acid, acetic acid, formic acid, etc. Also, as a solvent for preparing an aqueous solution, although water is industrially preferred, a mixed solvent of water-miscible organic solvents such as alcohols, ketones, and dimethylformamide and water may also be used.

The carboxyl group of the fiber having the core-sheath structure obtained by the above-mentioned method, since most of it is a basic carboxyl group that turns the cation from the basic metal compound into a counter ion, is further treated with an acid. Convert a base-type carboxyl group to an H-type carboxyl group. The method of acid treatment includes, for example, a method of immersing fibers having the aforementioned core-sheath structure in an aqueous solution of an acidic substance, or a method of spraying the aqueous solution on the fibers. Thus, acidic substances, for example, may be, for example, nitric acid, sulfuric acid, hydrochloric acid, formic acid, and the like.

Finally, the impregnated fibers are dehydrated and dried to obtain fibers with a core-sheath structure converted into H-type carboxyl groups.

The water-absorbent nonwoven fabric precursor of the present invention is characterized in that it contains the above-mentioned water-absorbent fiber precursor, and is formed by the spinning lace processing structure, that is, the spinning lace method (water flow entangling method), which has fibers in a entangled state. Non-woven. Since the water flow in spinning lace processing does not protrude from the surface of the non-woven fabric as much as the needles of the needling method, it is difficult for the fibers to protrude on the surface of the non-woven fabric during the manufacturing steps. Moreover, since the water flow is fine and its number is also large, the entanglement of the fibers becomes stronger. Therefore, in the spun lace processing structure, the generation of plush becomes less.

For the production of such fluff, the water-absorbent nonwoven fabric precursor of the present invention preferably has 10 or less fibers, more preferably 8 or less fibers, and more preferably 6 or less fibers in the evaluation method described later. The following plush things. When the number of plush is more than 10, even if a mask is formed by the method described below using, for example, a water-absorbent nonwoven precursor, it is likely to cause itching and give discomfort when it is placed on the skin. inappropriate situation. Also, after wearing the mask, fluff will easily remain on the skin.

In addition, in the water-absorbent nonwoven fabric precursor of the present invention, it is desirable that the content of the above-mentioned water-absorbent fiber precursor is preferably 10-100%, more preferably 20-90%, and more preferably 30-80%. By making the water-absorbent fiber precursor 10% or more, it becomes easy to obtain sufficient water content even in applications such as facial masks, because it is excellent in terms of practicality.

Moreover, in the water-absorbent nonwoven fabric precursor of this invention, you may mix and use fibers other than a water-absorbent fiber precursor as needed. In terms of fibers that can be mixed here (hereinafter also referred to as mixed fibers), it can be used: natural fibers such as pulp, cotton, hemp, silk, and wool; Synthetic fibers of recycled fiber, acrylic, polyester, polyolefin, polyurethane, polyamide, polyethylene, polypropylene, etc.; using polyethylene, polypropylene, polyester, polyamide, polyolefin, etc. Thermally adhesive fibers of thermoplastic polymers, etc. Also, as thermally adhesive fibers, it is possible to use a core-sheath structure in which two or more types of polymers with different melting points are used, and a polymer with a high melting point is used for the core and a polymer with a low melting point is used for the sheath. Or side by side (side by side) construction, etc.

The fineness of the above blended fibers is preferably in the range of 0.5-3.0 dtex. If it is less than 0.5 dtex, there is a possibility that the cotton passability of the carding machine may become poor in the web forming step when the nonwoven fabric is produced. Also, when the dtex exceeds 3.0, there is a possibility that the adhesiveness to the skin will be insufficient when processed into a mask or the like. This kind of fineness is more preferably in the range of 0.5-2.7 dtex.

Also, the weight per unit area of the water-absorbent nonwoven fabric precursor of the present invention is preferably 10-100 g/m ² . When the weight per unit area is less than 10 g/m ² , it may not have sufficient strength as a nonwoven fabric. Also, if the weight per unit area exceeds 100 g/m ² , the water absorption will increase too much, the nonwoven fabric will become heavier, and when used as a mask, etc., it will be easier to peel off than the wearing part. Such weight per unit area is more preferably 15 to 80 g/m ² .

The above-mentioned water-absorbent nonwoven fabric precursor of the present invention can be produced by the usual spinning lace method by using the above-mentioned water-absorbent fiber precursor and mixed fibers as needed to make a carding web. In the water-absorbent fiber precursor used in the present invention, since the amount of basic carboxyl groups is reduced and the amount of H-type carboxyl groups is increased, and the water absorption performance is inhibited, gelation or brittleness of the fibers can be suppressed even when water flow is used. It can be processed into non-woven fabrics by spinning lace. The water-absorbent non-woven fabric precursor of the present invention produced by spinning lace processing in this way has sufficient strength and shape stability even without thermal bonding points, and becomes a soft non-woven fabric with less fluff.

Also, in the case of using heat-adhesive fibers as mixed fibers, after spinning lace processing, the heat-adhesive fibers are melted by hot rollers or hot air to allow the fibers to adhere to each other, and the strength or shape can be further improved. It has better stability and can also become a non-woven fabric with less fluff. However, when the content of the thermal adhesive fiber is too high, the nonwoven fabric may become too hard and the water retention may be insufficient. Therefore, the content of the heat-adhesive fiber is preferably at most 30% by mass, more preferably at most 20% by mass, and even more preferably at most 15% by mass, relative to the water-absorbent nonwoven fabric precursor. Moreover, in order to make the above-mentioned effect of increasing the strength and shape stability remarkable, the content is preferably at least 1% by mass, more preferably at least 3% by mass, and more preferably at least 5% by mass.

Next, the water-absorbent nonwoven fabric of the present invention can be produced by converting at least a part of the H-type carboxyl groups of the above-mentioned water-absorbent nonwoven fabric precursor into basic type carboxyl groups. The conversion method, for example, may be a method of immersing the water-absorbent non-woven fabric precursor in an aqueous solution of a cation-generating compound, or a method of spraying an aqueous solution or gas of a cation-generating compound on the water-absorbent non-woven fabric precursor, etc. .

Also, the compound generating a cation may be, for example, sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sodium carbonate, sodium bicarbonate, ammonium, or the like.

Such a water-absorbent non-woven fabric of the present invention is a material having characteristics based on the composition of the water-absorbent non-woven fabric precursor before conversion; specifically, it is a water-absorbent material containing a basic carboxyl group having 0.5 to 5.5 mmol/g. fibrous substance. When the amount of basic carboxyl groups in the water-absorbent fiber is less than 0.5 mmol/g, there arises a problem that sufficient water absorption cannot be obtained. On the contrary, when it exceeds 5.5 mmol/g, since the amount of water absorption increases, it may be difficult to maintain the shape of the formed nonwoven fabric or the shape of fibers. The amount of such basic carboxyl groups is preferably from 0.7 to 5.0 mmol/g, more preferably from 1.0 to 4.5 mmol/g.

Also, the water-absorbent nonwoven fabric of the present invention has the characteristics of a spun lace structure. In the spun lace processing structure as described above, less fuzz is generated.

In addition, the water-absorbent fiber content of the water-absorbent nonwoven fabric of the present invention is preferably from 10 to 100%, more preferably from 20 to 90%, and more preferably from 30 to 80%. Also, the water-absorbent fiber is preferably one having a core-sheath structure.

Also, when the water-absorbent nonwoven fabric of the present invention is used in a facial mask, etc., if the water absorption is too low, the moisturizing effect will be reduced because the lotion or the like cannot be sufficiently maintained; if the water absorption is too high, then It may be easy to cause inappropriateness such as falling off from the mounting part. Therefore, the water absorption rate of the water-absorbent nonwoven fabric is preferably from 500 to 20,000% by mass, more preferably from 1,000 to 15,000% by mass, relative to the water-absorbent nonwoven fabric.

The water-absorbent non-woven fabric precursor and the water-absorbent non-woven fabric of the present invention as described above have the possibility of being used in various applications; Wound dressings, patches for dry skin such as atopic dermatitis, pads for absorbent pants, soil water-retaining sheets, oil-water separation filter materials, etc.

For example, by cutting the water-absorbent nonwoven precursor of the present invention into a shape suitable for covering the face, it can be suitably used as a mask. The structure of such a face mask may be a single layer formed of one sheet of the water-absorbent nonwoven fabric precursor of the present invention from the cost point of view, but it may also be laminated with other nonwoven fabrics to form multiple layers of two or more layers. . In this case, it is preferable to laminate non-woven fabrics with different characteristics, for example, the structure formed by disposing the water-absorbent non-woven fabric precursor of the present invention on the side that contacts the skin, and laminating polyester non-woven fabrics on it, so as to increase the strength of the non-woven fabrics , and even in the wet state of inhaling lotion, it can be easily bent and opened.

As mentioned above, the facial mask made of the water-absorbent nonwoven fabric precursor of the present invention can be sold in a dry state, and consumers can use it by soaking the facial mask with lotion and covering the face. On this occasion, pH regulators such as sodium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide, sodium citrate, sodium ascorbate, and sodium aspartate contained in lotion, and sodium hyaluronate A cation-generating compound with an alkali metal salt of a moisturizing agent such as the like, converts the H-type carboxyl group of the water-absorbing non-woven fabric precursor into a basic-type carboxyl group to form a water-absorbing non-woven fabric, and the lotion obtained by the method described later A sufficient amount of lotion that can maintain a water absorption rate of 1000% by mass or more.

Also, after putting the above-mentioned dried facial mask into a bag such as an aluminum bag, by filling the bag with lotion and sealing it, it can be sold as a mask that is pre-impregnated with lotion. . In this case, the consumer purchases the facial mask that has been filled with this kind of lotion, and naturally does not need to impregnate it with lotion and can use it directly as it is. "Example"

Hereinafter, although an Example is illustrated in order to facilitate understanding of this invention, these are only illustrations after all, and therefore the gist of this invention is not limited to these of course. In addition, the parts and percentages in the examples are expressed on a mass basis unless otherwise specified. The evaluation method of the characteristic in an Example is as follows.

＜Total carboxyl group content＞ Immerse about 1 g of fiber sample in 50 ml of 1 mol/l hydrochloric acid aqueous solution for 30 minutes. Next, immerse the fiber sample in water with a bath ratio of 1:500. After 15 minutes, when it is confirmed that the bath pH is 4 or more, it is dried (when the bath pH is less than 4, water washing is performed again). Next, accurately weigh about 0.4g of fully dried fiber sample (W1 [g]), add 100ml of water, and further add 15ml of 0.1mol/l sodium hydroxide aqueous solution, 0.4g of salinized sodium and phenolphthalein and stirred. After 15 minutes, titrate with 0.1 mol/l hydrochloric acid aqueous solution until the phenolphthalein does not develop color, and calculate the consumption of hydrochloric acid aqueous solution (V1 [ml]). From the obtained measured values, the amount of total carboxyl groups was calculated by the following formula. Total carboxyl group [mmol/g] = (0.1×15-0.1×V1)/W1

<Amount of H-type carboxyl groups and amount of base-type carboxyl groups> In the above method of measuring the amount of total carboxyl groups, the amount of H-type carboxyl groups was calculated in the same manner except that the initial immersion in a 1 mol/l aqueous hydrochloric acid solution and the subsequent water washing were not performed. The amount of basic carboxyl groups was calculated by subtracting the amount of such H-form carboxyl groups from the above-mentioned amount of total carboxyl groups.

＜Water Absorption of Precursor Fiber＞ Soak about 0.5g of the sample in pure water, keep it at 25°C for 30 minutes, cover it with nylon filter cloth (200 mesh), and remove the fiber by a centrifugal dehydrator (160G×5 minutes, but G is the acceleration of gravity) moisture in between. Measure the weight (W2 [g]) of the sample adjusted in this way. Next, this sample was dried in a vacuum dryer at 80° C., and the weight thereof was measured to a constant weight (W3 [g]). From the above measurement results, the water absorption rate was calculated by the following formula. Water absorption [%] = (W2-W3)/W3×100

＜Water absorption when neutralization degree is 50%＞ The fiber precursor used as a sample was immersed in an aqueous solution of sodium carbonate whose concentration was adjusted so that the degree of neutralization was 50% relative to the total carboxyl groups of the fiber precursor, immersed at 30°C for 1 hour and taken out. Next, it was immersed in methanol, and the water was removed with methanol. After the water was removed, fibers with a degree of neutralization of 50% were obtained by twisting, fiber opening, and drying. For the obtained fibers, the water absorption was measured in the same manner as in the preceding paragraph.

＜Confirmation of core sheath structure＞ After dyeing the sample with a cationic dye, the cross section of the fiber was observed with an optical microscope. In the case of the core-sheath structure, it was confirmed that the density or hue of the color is different between the surface layer and the center.

＜Number of Plush＞ Visually measure: within a square of 10 cm on one side of the non-woven fabric, the number of piles whose ends protrude from the surface of the non-woven fabric and whose length is more than 3 mm. The same measurement is also performed for other arbitrary 2 places, and the average value of the measurement results of all 3 places is used as the number of plush.

＜Water absorption rate of absorbent nonwoven fabric＞ The nonwoven fabric precursor used as the sample was immersed in an aqueous sodium carbonate solution whose concentration was adjusted to the amount of basic carboxyl groups shown in Table 2, immersed at 30°C for 1 hour and taken out. Next, it was dipped in methanol, water was removed with methanol, and after water removal, twisting, fiber opening, and drying were carried out to obtain a water-absorbent nonwoven fabric. Soak about 0.5g of the non-woven fabric in pure water, keep it at 25°C for 30 minutes, wrap it with nylon filter cloth (200 mesh), and remove it by a centrifugal dehydrator (160G×5 minutes, but G is the acceleration of gravity) Moisture between fibers. Measure the weight (W4 [g]) of the sample adjusted in this way. Next, this sample was dried in a vacuum dryer at 80° C., and the weight thereof was measured until it became a constant weight (W5 [g]). From the above measurement results, the water absorption rate was calculated by the following formula. Water absorption [%] = (W4-W5)/W5×100

＜Diameter＞ Put the sample into the constant temperature and humidity device under the atmosphere of 20℃×65%RH in advance for 24 hours. The fibers conditioned in this way were measured according to the positive fineness A method of JIS L 1015:2010.

＜Fiber length＞ Put the sample into the constant temperature and humidity device under the atmosphere of 20℃×65%RH in advance for 24 hours. Fibers conditioned in this way are measured in accordance with the average fiber staple diagram method (A method) of JIS L 1015:2010.

<Weight per unit area> After the sample was cut into 10 cm×10 cm, it was dried at 105° C. for 2 hours, and the weight (W6 [g]) of the sample was measured. From the above results, it is calculated by the following formula. Weight per unit area [ g/m ² ] = W6/(0.1×0.1)

[Manufacturing example 1] For the spinning stock solution formed by dissolving 10 parts of acrylonitrile-based polymer composed of 90% acrylonitrile and 10% methyl acrylate in 90 parts of 48% sodium thiocyanate aqueous solution, follow the usual method Spinning, washing, stretching, drying, crimping, heat treatment, and cutting are performed to obtain acrylic fibers as raw materials. Next, after attaching such an acrylic fiber to a mixed aqueous solution containing 0.13% of hydrazine and 35.0% of sodium hydroxide, it is twisted so that the liquid absorption relative to the fiber mass becomes 100%. 106°C x 15 minutes for cross-linking hydrolysis treatment and water washing. The water-absorbent fiber precursor A was obtained by immersing the washed fibers in 0.1% sulfuric acid aqueous solution at 30°C for 1 hour, dehydrating, adding oil, dehydrating, opening, and drying. Table 1 shows the evaluation results of the fiber precursors.

[Manufacturing example 2] In Production Example 1, the water-absorbent fiber precursor B was obtained in the same manner except that the conditions of the crosslinking hydrolysis treatment were set to 100° C.×5 minutes. Table 1 shows the evaluation results of the fiber precursors.

[Manufacturing example 3] In Production Example 1, the water-absorbent fiber precursor C was obtained in the same manner except that the conditions of the crosslinking hydrolysis treatment were set to 109° C.×30 minutes. Table 1 shows the evaluation results of the fiber precursors.

[Manufacturing example 4] In Production Example 1, the water-absorbent fiber precursor D was obtained in the same manner except that the conditions of the crosslinking hydrolysis treatment were set to 109° C.×10 minutes. Table 1 shows the evaluation results of the fiber precursors.

[Manufacturing example 5] Wash the "fibers immersed in 0.1% sulfuric acid aqueous solution at 30°C x 1 hour" in Production Example 1, add an aqueous solution containing 0.6 equivalent of sodium carbonate relative to the total carboxyl groups of the fibers, and make Soak it at 30°C for 1 hour. Next, dehydration was carried out by immersing in methanol containing a textile oil agent, fiber opening and drying were performed after twisting, and the water-absorbent fiber precursor E of manufacture example 5 was obtained. Table 1 shows the evaluation results of the fiber precursors.

[Manufacturing example 6] Using the acrylic fiber shown in Production Example 1 as a raw material, in an aqueous solution containing 0.5% by mass of water plus hydrazine and 2.0% by mass of sodium hydroxide, simultaneously perform cross-linking introduction treatment at 100°C for 2 hours and hydrolysis treatment; treatment at 100° C. for 3 hours with 8 mass % nitric acid aqueous solution; water-absorbent fiber precursor F of Production Example 6 was obtained by washing with water and drying. Table 1 shows the evaluation results of the fiber precursors.

"Table 1"

[Embodiments 1 to 4] Each water-absorbent fiber precursor was mixed with acrylic fiber (fineness 0.9 dtex, fiber length 51 mm) in such a manner as to form the content shown in Table 2 to prepare a carded web, and spinning was carried out on the carded web. The water-absorbent nonwoven fabric precursors of the various examples were obtained by processing yarn lace. Table 2 shows the properties of the obtained nonwoven fabric precursor.

In addition, in the spinning lace method, a multi-purpose nonwoven fabric manufacturing device manufactured by Kawanoe Seiki Co., Ltd. was used, and three jet nozzles were used with a pitch of 0.1 mmφ×1 mm. The water pressure of the 3 nozzles is respectively set as follows: the first nozzle is 2MPa, the second nozzle is 5MPa, and the third nozzle is 5MPa; the water jets are hit from the inside and the outside, and the non-woven fabric is obtained by interlacing the water flow.

[Comparative examples 1 to 2] In Example 1, the water-absorbent nonwoven fabric precursors of Comparative Examples 1 and 2 were obtained in the same manner except that the water-absorbent fiber precursors E and F were used instead of the water-absorbent fiber precursor A. Table 2 shows the evaluation results of these nonwoven fabric precursors. In Comparative Example 1, since the water-absorbent fiber precursor E had a large amount of basic carboxyl groups, it absorbed too much water when spinning lace, so that a nonwoven fabric could not be obtained. In addition, in Comparative Example 2, it is presumed that there are many cross-linked structures introduced in view of the production method of the water-absorbent fiber precursor F, so that the water-absorbing rate is low.

[Comparative examples 3-4] Each water-absorbent fiber precursor was mixed with heat-fused fibers (core-sheath fibers with polypropylene core and polyethylene sheath, fineness 2.2 dtex, fiber length 51 mm) were mixed to make a carded web; a water-absorbent nonwoven fabric precursor produced by thermal bonding was obtained by heating the carded web at 160°C with a heating roller. Table 2 shows the properties of the obtained nonwoven fabric precursor. Compared with the nonwoven precursor obtained by the spinning lace method, as shown in Table 2, the nonwoven precursor produced by the thermal bonding method has more fluff.

[Comparative Example 5] The water-absorbent fiber precursor and acrylic fiber (denier 0.9 dtex, fiber length 51 mm) were mixed so as to have the content shown in Table 2 to make a carded web, and the Carded webs are processed into absorbent nonwoven precursors. Table 2 shows the properties of the obtained nonwoven fabric precursor. As shown in Table 2, compared with the nonwoven precursors obtained by the spinning lace method and the thermal bonding method, the nonwoven precursor obtained by the acupuncture method has more fluff.

"Table 2"

As shown above, any of Examples 1 to 4 had little fluff and exhibited a favorable water absorption rate. On the other hand, in Comparative Example 1, since the amount of basic carboxyl groups was large, the water-absorbent fiber precursor absorbed too much water when spinning lace, and a nonwoven fabric could not be obtained. In Comparative Example 2, the cross-linked structure of the water-absorbing precursor was too much and the water absorption rate was insufficient. Also, in Comparative Examples 3 and 4, it was a substance with a lot of fluff, and in Comparative Example 5, it was a substance with more fluff.

[Example 5] Add 0.60 g of 10% by mass sodium carbonate aqueous solution as a cation-generating compound to 30 g of lotion (Shiseido Co., Ltd. "Muscle Water Natural Body Lotion Blue Label"), and stir for 10 minutes to prepare a lotion mixture . Next, about 0.6 g of the dried water-absorbent nonwoven fabric precursor of Example 1 was cut out and precisely weighed (W1 [g]). The nonwoven fabric precursor was soaked in the aforementioned lotion mixture, and left at room temperature for 3 days to absorb the lotion. Next, the nonwoven fabric absorbed with the lotion was left to stand for 5 minutes in a suspended state, and the weight (W2 [g]) was measured in a state where water droplets did not fall. When the water absorption rate of the lotion was calculated from the obtained measured value using the following formula, it was 2220%, which is a substance having a sufficient water absorption rate of the lotion. Water absorption rate of lotion [%] = (W2-W1)/W1×100

[Example 6] In Example 5, the water absorption rate of the lotion was calculated in the same manner except that the 10 mass % sodium carbonate aqueous solution was not added, and it was 1550%. Because of the addition of sodium carbonate, which is a compound that generates cations, although the water absorption rate of the lotion does not reach the level of Example 5; however, it can be understood that even the compound that generates cations contained in the lotion at the beginning can also exhibit the water absorption performance of the lotion. .

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Claims (11)

A water-absorbent fiber precursor, characterized in that it has a core-sheath structure in which the core part is an acrylonitrile-based polymer, an H-type carboxyl group of 0.1-5.0 mmol/g, and a basic-type carboxyl group of less than 0.5 mmol/g; the aforementioned H The sum of the amount of carboxyl groups and the amount of carboxyl groups of the above-mentioned basic type is 0.5 mmol/g or more; the water absorption rate is 10 to 1000 mass %, and the water absorption rate is 500 to 50000 mass % when the degree of neutralization of carboxyl groups is adjusted to 50% . The water-absorbent fiber precursor as described in claim 1 has a cross-linked structure. A water-absorbent non-woven fabric precursor, which is characterized in that it contains the water-absorbent fiber precursor as claimed in claim 1 or 2, and has a spun lace (silk lace) processing structure. The water-absorbent nonwoven fabric precursor described in claim 1 or 2, in the following evaluation method, the number of piles is 10 or less, (evaluation method) visual measurement: within the range of a square of 10 cm per side, The end is the number of piles protruding from the surface of the nonwoven fabric and having a length of 3 mm or more. The same measurement is also performed for other arbitrary 2 places, and the average value of the measurement results of all 3 places is used as the number of plush. The water-absorbent nonwoven precursor as described in claim 3, wherein the content of the water-absorbent fiber precursor is 10 to 100%. A water-absorbent non-woven fabric, which is a water-absorbent fiber obtained by converting at least a part of the H-type carboxyl group of the water-absorbent fiber precursor described in claim 1 or 2 into a basic type carboxyl group, characterized in that it contains 5.5mmol/g basic type carboxyl water-absorbent fiber; water absorption rate is 500-20000% by mass, and has a spun lace structure. The water-absorbent nonwoven fabric as described in claim 6, wherein the content of water-absorbent fibers is 10 to 100%. A facial mask (face mask), characterized in that: it has any The water-absorbent non-woven fabric precursor described in item 1, or the water-absorbent non-woven fabric described in claim 6 or 7. A mask filled with lotion, characterized in that: lotion has been filled in the mask as described in Claim 8. A method for manufacturing a water-absorbent nonwoven precursor, characterized in that it includes the step of interlacing a card web containing the water-absorbent fiber precursor as described in claim 1 or 2 by spinning lace. A method for manufacturing a water-absorbent nonwoven fabric, characterized in that: the step of interlacing the carding web containing the water-absorbent fiber precursor according to any one of claims 1 to 3 by the spinning lace method, and having the step of making the A step of converting at least a part of the aforementioned H-type carboxyl groups into basic-type carboxyl groups by acting on the water-absorbent nonwoven fabric precursor obtained in this step with a cation-generating compound.