JP4536229B2 - Elastic wet sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is an elastic wet sheet excellent in various properties such as elasticity, flexibility, liquid retention, mechanical performance, etc., and further elastic wetting excellent in various properties such as elasticity, flexibility and liquid retention by containing liquid. The present invention relates to a rigid molded body to be a sheet and a method for producing the same, and also relates to a liquid retaining material and a wiping material using the elastic wet sheet.
[0002]
[Prior art]
Conventionally, various films, porous materials, hydrogels, and the like have been proposed as highly liquid-absorbing materials suitable for liquid retaining materials. However, these are inferior in flexibility and texture, and there is a problem that sufficient liquid retention is not obtained.
On the other hand, Japanese Patent Application Laid-Open No. 2-200232 discloses a method for producing a highly water-resistant wiping material in which a polyvinyl alcohol (PVA) aqueous solution is applied to a nonwoven fabric and then solidified, and then the resulting porous sheet is acetalized. ing. Although the sheet obtained by this method is excellent in liquid retention, the inherent flexibility of the nonwoven fabric is impaired because the surface of the nonwoven fabric is coated with resin. Sheets that are inferior in flexibility, texture, etc. are unsuitable for use in contact with human skin and the like, and are difficult to use along curved surfaces or processed into various shapes.
[0003]
Further, JP-A-2-112407 and JP-A-2-145809 disclose freezing and water-containing fibers obtained by discharging an aqueous solution (spinning stock solution) containing a PVA polymer and polyacrylic acid to a salt bath. It is disclosed that a highly hydrogel fiber is produced by repeating the drying treatment, and it is also shown that the fiber is used as a fabric such as a nonwoven fabric. Although the nonwoven fabric is superior in flexibility and texture as compared to a film or the like, the flexibility and texture cannot be sufficiently improved by simply forming the PVA fiber into a nonwoven fabric, and liquid retention I can't get anything that is satisfactory.
[0004]
[Problems to be solved by the invention]
The object of the present invention is to provide an elastic wet sheet excellent in various properties such as elasticity, flexibility, liquid retention, mechanical performance, etc., further obtained from the elastic wet sheet, and re-impregnated for elasticity, flexibility, It is providing the liquid holding material and wiping material which use the elastic wet sheet regarding the hard molded object used as the elastic wet sheet excellent in various performances, such as liquid retention, and its manufacturing method.
[0005]
[Means for solving problems]
The present invention
(1) An elastic wet sheet obtained by impregnating a nonwoven fabric with a liquid having a temperature of 50 ° C. or less at 50 mass% or more, 50% elongation recovery rate 60% or more, tearing length 3 km or more, liquid retention rate 100 to 500% , Dry bulk density 0.5g / cm ^Three 30% by mass or more of the fibers constituting the sheet are polyvinyl alcohol fibers having a dissolution temperature in water of 60 ° C. or more, and the polyvinyl alcohol fibers have a saponification degree of 98 mol% or more. An elastic wet sheet having a sea-island structure having a sea component and a vinyl alcohol polymer having a saponification degree of 97 mol% or less as an island component,
(2) Bulk density 0.5g / cm ^Three An elastic wet sheet obtained by impregnating the following non-woven fabric with a liquid having a temperature of 50 ° C. or less in an amount of 50% by mass or more, wherein 30% by mass or more of the fibers constituting the non-woven fabric has a dissolution temperature in water of 60 ° C. or more. The polyvinyl alcohol fiber has a sea-island structure in which a vinyl alcohol polymer having a saponification degree of 98 mol% or more is a sea component and a vinyl alcohol polymer having a saponification degree of 97 mol% or less is an island component. An elastic wet sheet, characterized in that
(3) A hard molded body obtained by drying and / or heating the elastic wet sheet according to (1) or (2),
(4) A method for producing a hard molded body for drying and / or heating the elastic wet sheet according to (1) or (2),
(5) A method for producing a wet elastic sheet, wherein the hard molded body according to (3) contains 50% by mass or more of a liquid having a temperature of 50 ° C. or lower,
(6) A liquid retention material using the elastic wet sheet according to (1) or (2),
(7) A wiping material obtained using the elastic wet sheet according to (1) or (2),
About.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The present invention has been found that by applying a liquid to a specific nonwoven fabric, a high-performance elastic wet sheet that is flexible and excellent in various properties such as liquid retention, elasticity, flexibility, and mechanical performance can be obtained. is there.
In the present invention, first, the bulk density is 0.5 g / cm. ^Three Or less, preferably 0.3 g / cm ^Three Or less, more preferably 0.25 g / cm ^Three It is necessary to use the following nonwoven fabric. Since the nonwoven fabric is bulky and has a large number of voids between the fibers, excellent liquid absorbency and flexibility are exhibited. When a non-woven fabric having a high bulk density is used, a wet sheet excellent in liquid absorbency and flexibility cannot be obtained. However, if the bulk density is too low, the mechanical performance of the sheet becomes insufficient, and the void size after the liquid inclusion is too large, so that the liquid is easily drained by external stress. Therefore, the bulk density is 0.05 g / cm ^Three Above, especially 0.08g / cm ^Three The above is preferable. The bulk density can be adjusted by changing the fineness of the fibers used, the method for producing the nonwoven fabric, the thermocompression bonding conditions, and the like.
The basis weight of the nonwoven fabric used in the present invention is 10 to 500 g / m from the viewpoints of handleability, flexibility, mechanical performance and the like. ² Degree, especially 50-300 g / m ² It is preferable that it is about.
[0007]
However, the desired wet elastic sheet cannot be obtained simply by using the bulky nonwoven fabric as described above. That is, the bulky nonwoven fabric has high flexibility and can absorb a large amount of liquid because it has a large number of voids between the fibers. On the other hand, the sheet strength tends to be insufficient due to less entanglement between the fibers, and the external pressure is low. If added, it will easily deform and drain easily. However, if a binder resin or the like is added to increase the sheet strength, the sheet flexibility and liquid absorbency are impaired.
In order to solve the above problems, the present invention has been found to blend a specific polyvinyl alcohol (PVA) fiber. Specifically, by blending a specific PVA-based sea-island structure fiber having a dissolution temperature in water of 60 ° C. or higher, the sheet strength is remarkably enhanced without impairing the liquid absorbency, liquid retention, flexibility and the like. .
[0008]
That is, when the nonwoven fabric absorbs liquid, the PVA fibers constituting the nonwoven fabric swell, and as a result, the fibers are more closely adhered to each other and the entanglement between the fibers is strengthened. Therefore, even if the sheet of the present invention absorbs the liquid, the mechanical performance does not decrease. Rather, since the mechanical performance of the sheet is improved by the liquid absorption, the desired mechanical performance can be obtained without adding a resinous binder or the like. can get. Moreover, since the PVA fiber dissolves in a very small amount when it absorbs liquid and exhibits the binder ability, the mechanical performance of the sheet can be further enhanced. In particular, by drying the wet sheet, it becomes possible to obtain a hard molded body (hard sheet or the like) excellent in mechanical strength.
[0009]
Furthermore, in general, there is a problem that the liquid present in the interfiber gap easily drains due to external stress. However, in the present invention, when the sheet absorbs liquid, the PVA fiber swells and the interfiber gap size decreases. Therefore, a very small amount of liquid is present in the interfiber space in a free state, and most of the liquid is in a state of being retained in the PVA fiber excellent in liquid absorbency. Therefore, the wet sheet of the present invention is difficult to drain even when external stress is applied, and can secure excellent liquid retention (liquid retention).
Moreover, since the PVA fiber used in the present invention swells to become a gel, the wet sheet of the present invention is excellent in elasticity and flexibility and exhibits a crisp feel. Therefore, the wet sheet of the present invention is a material suitable for a liquid retaining material and a poultice base material.
[0010]
In the present invention, it is necessary that the dissolution temperature of the PVA fiber in water is 60 ° C. or higher, preferably 70 ° C. or higher. If the fiber dissolution temperature in water is too low, a large amount of PVA will elute if liquid is applied, so that the liquid retention and mechanical performance of the wet sheet will be insufficient, and the nonwoven fabric manufacturing process and storage conditions will be strictly controlled. Need arises. For the same reason, the elution rate of the fibers is preferably 5% by mass or less, particularly preferably 2% by mass or less. However, the dissolution temperature of the fibers in water is 100 ° C. or less, particularly 95 ° C. or less from the standpoint of elution of the fibers in a very small amount to exhibit the binder ability and efficiently increase the mechanical performance of the elastic sheet and the hard molded body. Is preferred. For the same reason, the elution rate of the PVA fiber is preferably 0.05% by mass or more, particularly preferably 1% by mass or more.
[0011]
Furthermore, in the present invention, it is necessary to use a specific PVA-based sea-island structure fiber from the viewpoint of swelling the fiber at the time of liquid containing, improving the liquid retention property, mechanical performance, etc. of the wet sheet, and expressing a crisp feel. is there. More specifically, a vinyl alcohol polymer (polymer A) having a saponification degree of 98 mol% or more is a sea component, and a vinyl alcohol polymer (polymer B) having a saponification degree of 96 mol% or less is an island component. It is necessary to use sea-island structure fiber. By adopting this configuration, the polymer (Polymer B) is dissolved and swollen by the liquid that has penetrated into the inside of the fiber to make the island component flexible, and the degree of swelling of the fiber is improved, so that a desired elastic wet sheet is obtained. It becomes possible. In the case of a fiber made of only polymer B, for example, when it is immersed in room temperature water, it is completely eluted, but in the case of the above fiber, although the fiber surface has liquid permeability, polymer A having excellent water resistance Since it is coated, the polymer B does not elute more than necessary, so that the flexibility, elasticity, etc. of the sheet can be improved without impairing the liquid retention property, mechanical performance, and the like. On the other hand, when fibers consisting only of polymer-A are used, the inter-fiber voids are not greatly reduced even when liquids containing bulky non-woven fabrics, because they do not swell sufficiently even if they are liquid-containing, although there is no problem with water resistance. Therefore, it becomes a wet sheet which is easily drained by external pressure and inferior in mechanical performance. Further, since the fibers do not swell sufficiently, a crisp feel is not exhibited.
[0012]
In order to obtain the effect of the present invention, the saponification degree of the polymer A needs to be 98 mol% or more. However, the degree of saponification is 99.5 mol% or less, particularly 99 from the viewpoint of enhancing the swelling property of the fiber. It is preferable to make it mol% or less, and it is more preferable that it is 1000-2000 degree of polymerization from points, such as water resistance and swelling property.
The saponification degree of the polymer B is 97 mol% or less, preferably 96 mol% or less, more preferably 80 mol% or less from the viewpoint of increasing the degree of swelling of the fiber, from the viewpoint of ensuring the water resistance of the fiber. Is preferably 60 mol% or more, particularly 65 mol% or more. From the viewpoint of water resistance and swelling, the degree of polymerization is preferably 300 to 2000, and more preferably 300 to 1000.
By using the sea-island structure fiber as described above, it becomes possible to obtain a PVA-based fiber having excellent liquid retention such as a swelling degree of 100% or more, particularly 150% or more. However, if the degree of swelling of the PVA fiber is too large, the inter-fiber voids when wet are excessively reduced, and the flexibility of the sheet is liable to be impaired. Therefore, the degree of swelling of the fiber is 400% or less, particularly 300 % Or less is preferable.
[0013]
The island component may be continuous in the fiber axis direction, but is not necessarily continuous, and may be in the shape of a sphere or an intermittent elongated rod or rugby ball. Further, the island component may be partially exposed on the fiber surface. From the viewpoint of mechanical performance, swellability and the like, the constituent ratio of the island component is preferably 1 to 45% by mass / fiber, particularly 10 to 35% by mass / fiber.
[0014]
In the present invention, it is necessary to use at least a PVA fiber. Since the PVA fiber is excellent in various properties such as liquid absorption, swelling, and mechanical performance, a high-performance wet sheet can be obtained. The PVA fiber referred to in the present invention is a fiber containing a vinyl alcohol polymer, and another polymer may be further blended. From the viewpoint of fiber swellability, cost, etc., it is preferable that the vinyl alcohol polymer is made 50% by mass or more, particularly 80 to 100% by mass.
[0015]
The vinyl alcohol polymer used in the present invention may be modified with other units, and a polymer having a hydrophilic group introduced therein can be suitably used from the viewpoint of liquid absorbency. Specific examples include vinyl alcohol polymers modified with allyl alcohol, aryl sulfonic acid, vinyl pyrrolidone and the like. However, if the modification rate becomes too large, the mechanical performance deteriorates or the elution rate becomes too large. Therefore, the proportion of the modification unit is preferably 10 mol% or less, and more preferably 5 mol% or less.
[0016]
The production method of the PVA-based sea-island structure fiber (fiber X) used in the present invention is not particularly limited, and can be produced by, for example, a dry spinning method, a dry wet spinning method, a wet spinning method, or the like. The dry-wet method refers to a method of spinning by forming a space (air-gap) filled with air or inert gas between the spinning nozzle and the solidification bath.
In view of production processability, cost, etc., it is preferable to produce fibers by wet spinning or dry wet spinning. As a specific production method, for example, there is a method in which a spinning stock solution composed of an aqueous solution containing PVA is wet-spun from a spinneret into a solidification bath at room temperature containing inorganic salts having dehydrating ability. The concentration of the PVA polymer in the spinning dope varies depending on the degree of polymerization, but is preferably 5 to 40% by mass, particularly 10 to 30% by mass.
[0017]
The solidifying solution is not particularly limited as long as it has a solidifying ability for the spinning stock solution, but from the viewpoint of processability and cost, it is preferable to use a solidifying solution using water as a solvent. Specifically, an aqueous solution of a salt having a dehydrating ability such as sodium sulfate (sodium sulfate), ammonium sulfate, or sodium carbonate is used. Of these, a saturated aqueous solution coagulation bath is preferably used from the viewpoint of processability and cost. A method of discharging a spinning stock solution containing about 0.1 to 3% by mass of boric acid to an alkaline solidification bath containing sodium hydroxide or the like can also be suitably employed. The temperature of the solidification bath is preferably 20 to 70 ° C, particularly 30 to 50 ° C. The spinning raw yarn can be easily produced by subjecting the yarn from the solidification bath to wet heat drawing and drying as desired.
[0018]
In addition, it is difficult to cause interfiber sticking, and from the viewpoint that crimps suitable for card processability can be easily provided, a PVA fiber is obtained by a wet discharge method into a solidification bath using a solution obtained by dissolving PVA in an organic solvent as a spinning stock solution. Preferably it is manufactured. The following method is preferably used.
As the solvent constituting the spinning dope, an organic solvent that dissolves PVA is preferably used, and examples thereof include polar solvents such as dimethyl sulfoxide (DMSO), dimethylformamide, and dimethylimidazolidine, and polyhydric alcohols such as glycerin and ethylene glycol. . Also, a mixture of two or more of these or a mixture of these with water may be used. Among many solvents, DMSO is a preferable solvent because it can dissolve PVA at a relatively low temperature and can prevent thermal deterioration and coloring of the PVA solution. At this time, since DMSO has a relatively high freezing temperature, it is preferable to add a low concentration of methanol or the like to lower the solidification point of the solidified liquid. The PVA concentration of the spinning dope varies depending on the polymerization degree of PVA and the type of solvent, but is usually 2 to 30% by mass, preferably 3 to 20% by mass.
[0019]
As the solidification bath, an organic solvent having a solidification ability for PVA is used. For example, alcohols such as methanol and ethanol, and ketones such as acetone and methyl ethyl ketone are not particularly limited as long as they have a solidifying ability for PVA. Among these, methanol is preferable because it is low in cost and has a relatively slow solidification ability and easily forms a uniform crystallite structure. In order to obtain high-strength fibers, the present invention may contain a stock solvent in the solidification bath. The content of the undiluted solvent varies depending on the type of organic solvent having solidification ability, but is preferably 10 to 50% by mass, particularly preferably 15 to 45% by mass, and a uniform gel can be easily obtained by mild solidification.
[0020]
The solidification bath temperature is preferably 20 ° C. or less, particularly 15 ° C. or less, and more preferably 10 ° C. or less from the viewpoint of obtaining a uniform solidified yarn. Dry-wet spinning via an air gap layer may be used between the nozzle and the solidification bath, but a wet spinning method is used in which the nozzle is in direct contact with the solidification bath in terms of fiber performance, spinning processability, etc. Is preferred.
Next, the obtained solidified thread is immersed in an extraction bath to wash away the stock solution solvent and the like in the solidified thread. The extraction bath is preferably composed of an organic solvent having a solidifying ability, etc., and is preferably subjected to wet heat stretching 2 to 8 times. A spinning raw yarn can be obtained by drying the yarn.
[0021]
Spinning yarns can be obtained by various methods as described above. However, from the viewpoint of improving fiber performance, it is preferable to proceed with oriented crystallization by hot drawing at a high temperature. In particular, when the above-described method using a spinning stock solution composed of an organic solvent is employed, fibers with less mechanical agglomeration between fibers and excellent mechanical performance can be obtained. Specifically, fibers with a strength of 5 cN / dtex or more can be obtained. .
There are no particular limitations on the method of hot drawing of the fiber, such as non-contact or contact type heaters, hot air furnaces, oil baths, high temperature steam. In particular, it is preferable to carry out a time of about 20 seconds to 3 minutes in a hot-air drawing furnace, and the drawing may be performed in two or more stages by controlling the temperature in multiple stages. The stretching temperature is preferably 100 to 250 ° C., and the total stretching ratio is preferably 8 to 25 times, particularly preferably 9 to 18 times. Of course, depending on circumstances, the drying shrinkage treatment can be performed at 110 to 230 ° C.
[0022]
When the fiber elution rate is too large, intramolecular and / or intermolecular cross-linking treatment may be performed in any step from the polymer production process to the nonwoven fabric production process. As the crosslinking agent, aldehydes such as formal, glutaraldehyde, nonane dial, tetramethoxynonane, or acetals thereof can be preferably used. However, it is necessary to pay attention to the degree of cross-linking and the like because the swelling and liquid absorption properties of the fiber are impaired when the cross-linking treatment is performed.
[0023]
In the present invention, a nonwoven fabric is obtained using the PVA fibers. Of course, fibers other than the PVA fiber (fiber X) may be used together. For example, as a fiber that can be used together with the PVA fiber, a PVA fiber other than the PVA fiber (fiber X) defined in the present invention is used. , Cellulose fiber, polyester fiber, polyamide fiber, polyvinyl chloride fiber, polyvinylidene chloride fiber, polyacrylonitrile fiber, polyclar fiber, polyolefin fiber (polyethylene fiber, polypropylene fiber, propylene-ethylene co-polymer) Polymer fibers, etc.), natural fibers such as cotton, hemp and natural pulp, and inorganic fibers such as glass fibers. For example, the dimensional stability, mechanical performance, and the like of the sheet can be improved by blending a fiber excellent in water resistance as compared with the fiber X. Moreover, when cotton etc. are mix | blended, a liquid retention property can be improved further. From the viewpoint of maintaining the liquid retention and mechanical performance of the wet sheet, it is preferable that the elution rate of the wet sheet is 15% by mass or less, particularly 5% by mass or less, and more preferably 1 to 2% by mass. Moreover, from the viewpoint of obtaining the effect of the present invention efficiently, the blending ratio of the PVA fiber (fiber X) is preferably 30% by mass or more, particularly 60% by mass or more, and more preferably 80 to 100% by mass. The fibers referred to in the present invention include not only those obtained by spinning, but also those obtained by slitting film-like materials, and beating products (pulp-like materials) obtained by beating fiber materials, etc. Include.
[0024]
Similarly, from the viewpoint of ensuring the liquid retention and flexibility of the wet sheet, the fineness of the fibers constituting the nonwoven fabric is preferably 10 dtex or less, particularly 5 dtex or less. The smaller the fineness, the easier it is to obtain a wet sheet with excellent texture and flexibility, and the void size between fibers is small, so that even if external stress is applied, it becomes difficult to drain liquid. As described above, since a specific PVA fiber is used in the present invention, when the liquid is contained, the fiber swells and the inter-fiber void size is reduced, and the drainage is effectively suppressed. By using such relatively thin fibers, the effect can be remarkably enhanced.
However, if the fiber diameter is too small, the size of the inter-fiber gap formed in the nonwoven fabric becomes too small and the liquid absorbency is impaired, and the nonwoven fabric manufacturing processability and the strength of the nonwoven fabric tend to be insufficient. Therefore, the fineness of the fiber is preferably 0.1 dtex or more, particularly 1 dtex or more.
The fiber length of the fibers constituting the nonwoven fabric may be set as appropriate, but from the viewpoint of sheet flexibility, processability and liquid retention, it is preferable to use short fibers with a fiber length of 1 to 200 mm, particularly 30 to 120 mm. .
[0025]
The method for producing the nonwoven fabric used in the present invention is not particularly limited. However, from the viewpoint of obtaining a sheet excellent in texture, flexibility, liquid retention, etc., it is necessary to use a nonwoven fabric having a low bulk density. It is preferable to produce a non-woven fabric. Although a nonwoven fabric (paper) may be produced by a wet papermaking method, it is generally desirable to produce a nonwoven fabric by a dry method because the bulk density of the nonwoven fabric obtained by the wet method increases.
As a method for producing the nonwoven fabric of the present invention, for example, a parallel web obtained by opening a filament tow by a repulsive action by triboelectric charging, or crimping a fiber and opening a cut staple with a card or the like is obtained. And a method of producing a nonwoven fabric by subjecting a fiber web such as a random web to entanglement treatment and / or thermocompression treatment. By adopting this method, inter-fiber sticking is efficiently suppressed, and inter-fiber voids are appropriately formed, so that a higher quality sheet can be obtained.
At this time, it is preferable to use crimped fibers to which the card passing property is imparted. More preferably, the number of crimps is 3 to 15 / inch, the crimp rate is 5 to 15%, and the crimp elastic modulus is 1. It is preferable to use a crimped fiber having ˜5%, particularly 5 to 12 crimps / inch, a crimp rate of 6 to 10%, and a residual crimp rate of 30 to 70%.
[0026]
Further, as the entanglement method, it is preferable to use a water entanglement method and / or a needle punch method. The conditions for needle punching are not particularly limited, but it is preferably applied to both sides of the sheet from the viewpoint of the form stability of the nonwoven fabric, and the number of needle punch treatments is 150 from the viewpoints of mechanical performance, form stability, texture, flexibility and the like. Times / cm ² 1000 times / cm ² The following is preferable. If the number of punches is increased, the mechanical performance of the nonwoven fabric is improved, but the flexibility and liquid absorbency are lowered. Therefore, it is preferable to set the number of punches according to the purpose. The number of needle punch processes is the number of times the sheet is entangled from both sides of the web by the needle, and can be determined by the density of the needles, the number of punches within a unit time, the web processing speed, and the like.
The cross-sectional shape of the needle is preferably circular or triangular, and the number of barbs is preferably about 3 to 40. The needle diameter of the blade portion is preferably 0.10 to 0.70 mm, particularly preferably 0.40 to 0.65 mm, from the viewpoint of the bulkiness, liquid absorption, mechanical performance, texture, etc. of the nonwoven fabric.
[0027]
When the water entanglement method is employed, it is preferable to use a nozzle plate in which nozzles having a diameter of 0.05 to 0.3 mm are arranged in one or two rows, and the jet pressure of the jet water flow is 5 to 50 kg / cm. ² It is preferable that The temperature of the water used for the water entanglement treatment is preferably 0 to 50 ° C.
A nonwoven fabric may be manufactured by combining multiple entanglement methods, but the needle punch method is adopted as an entanglement method from the viewpoint of suppressing the sticking between fibers and obtaining high liquid retention and feel. It is preferable to do this.
[0028]
Moreover, when the fiber which has thermocompression bonding is used, a nonwoven fabric can also be manufactured by a thermocompression-bonding process. When the thermocompression treatment is performed, the thermocompression area ratio is preferably 5 area% or more. Excellent mechanical performance and dimensional stability can be obtained at the thermocompression bonded portion. However, from the viewpoint of ensuring flexibility and liquid retention, it is preferable to suppress the thermocompression bonding area. Specifically, the entanglement treatment and / or the thermocompression treatment with a thermocompression bonding area of 50 area% or less (particularly 40 The non-woven fabric is preferably produced by an area% or less, and further 30 area% or less thermocompression treatment. If the thermocompression bonding area becomes too large, the fibers are firmly fixed, the flexibility is impaired, and the fibers cannot be sufficiently swollen.
As the heat embossed pattern, a deformed square pattern or a textured pattern having a desired pressure-bonding area ratio is suitable. At this time, from the point of uniformity, flexibility, liquid absorbency, etc. of the nonwoven fabric, when a 1 cm square size of the nonwoven fabric after the thermocompression treatment was cut out, any of the cut out samples had a crimped portion. It is preferable that the embossed pattern has a non-crimped portion. What is necessary is just to use a metal roll, a rubber roll, etc. as a heat roll.
[0029]
More preferably, the linear pressure in the thermocompression treatment is a linear pressure of 45 to 1000 N / cm or a surface pressure of 900 to 10000 Pa. The thermocompression bonding time is preferably as short as possible, specifically about 0.01 to 10 seconds.
The thermocompression bonding conditions (temperature / pressure) in the present invention are the temperature and pressure actually applied to the sheet, not the set temperature or set pressure. Actual temperature and pressure can be measured by a thermo label or a pressure indicator.
Moreover, when the thermocompression-bonding fiber is blended, the resulting nonwoven fabric can be easily processed into a desired shape (for example, a bag-like product, a cylindrical product, etc.) by subjecting it to a heat seal process.
[0030]
It is also possible to obtain a nonwoven fabric by using both the entanglement treatment and the thermocompression treatment, but it is preferable to obtain the nonwoven fabric without substantially performing the thermocompression treatment when it is desired to obtain a higher feeling and flexibility. . The entangled nonwoven fabric is excellent in texture and flexibility, and further, since the degree of freedom of the fiber is high, the swelling and shrinkage of the fiber is not hindered, and a more excellent effect is obtained.
Further, a binder resin or the like may be further added as long as the effect of the present invention is not impaired. However, from the viewpoint of efficiently obtaining the effect of the present invention, it is preferable that the binder resin or the like is not substantially added. .
[0031]
A desired wet elastic sheet is obtained by impregnating the nonwoven fabric obtained by the above method. From the viewpoint of obtaining a desired elastic wet sheet, the liquid content (liquid content) is 50% by mass or more, preferably 100% by mass or more, and more preferably 120% by mass or more. Is preferred. However, if the liquid content is too large, the fibers will be eluted more than necessary, or the liquid will be easily drained by external pressure or the like, so the liquid content is 500% by mass or less, particularly 400% by mass or less, and further 300% by mass or less. Is preferable. When the wet sheet is dried again, the bulk specific gravity (for example, 0.5 g / m) is the same as that of the non-woven fabric before liquid inclusion. ² A hard sheet having the following) is obtained.
The type of the liquid is not particularly limited, and examples thereof include liquids (including mixed liquids) such as water, alcohol, and organic solvents, or solutions obtained by adding other additives to these, dispersions, and the like. What is necessary is just to select suitably according to the objective. In particular, the effect of the present invention can be obtained more efficiently when an aqueous liquid is used. At this time, the temperature of the liquid to be contained needs to be 50 ° C. or less, preferably 40 ° C. or less, preferably from the viewpoint of suppressing the elution of the wet sheet more than necessary or the occurrence of interfiber sticking. It shall be 30 degrees C or less. Wet sheet weight (sheet weight including liquid) is 20 to 500 g / m ² Degree, especially 100-400 g / m ² The bulk density of the wet sheet is preferably 2.0 g / cm. ^Three Hereinafter, particularly 0.6 to 1.8 g / cm. ^Three It is preferable that it is about.
[0032]
According to the present invention, a wet sheet excellent in various performances such as elasticity, flexibility, mechanical performance, and touch feeling can be obtained. Specifically, a wet sheet having a liquid absorption rate of 300% by mass or more, particularly 400% by mass or more, and a liquid retention rate of 100% by mass or more, particularly 200% by mass or more is obtained. The liquid absorption rate and the liquid retention rate can be measured by the method described in the examples, but the liquid absorption rate is a value indicating the mass ratio occupied by the liquid contained in the interior of the fiber and between the fibers, Is a value indicating the mass ratio of the liquid substantially contained in the fiber (liquid that is difficult to drain due to external stress or the like). Liquid retention materials are required to have a high liquid absorption rate, but it is also important to have liquid retention that is difficult to drain due to external stress. It can be said that it is excellent as a liquid retaining material. According to the present invention, a wet sheet having (liquid retention / liquid absorption) of 0.3 or higher, particularly 0.4 or higher can be obtained.
[0033]
Furthermore, the sheet of the present invention is not only excellent in liquid absorption and liquid retention, but also excellent in elasticity and flexibility. For example, a wet sheet having a 50% elongation recovery rate of 60% or more, particularly 70% or more can be obtained. Further, a sheet having an elongation of 80% or more, particularly 90% or more, and further 100% or more can be obtained.
Moreover, the wet sheet of the present invention is excellent not only in liquid retention, flexibility and elasticity, but also in mechanical performance. Specifically, a wet sheet having a breaking length of 3 km or more, particularly 4 km or more, a strength of 18 N / 25 mm or more, further 25 N / 25 mm or more, particularly 30 N / 25 mm or more, especially 35 N / 25 mm or more is obtained.
[0034]
The sheet of the present invention can be used as it is, but it can also be used after being processed into a desired form, or may be a composite. For example, if desired, a laminated body in which one or more other layers are laminated in an arbitrary order is also possible. Examples of the layer that can be laminated include a fabric layer (woven or knitted fabric, nonwoven fabric, net-like material), a film layer, a metal foil layer, and the like. You can also Two or more layers of the nonwoven fabric of the present invention may be laminated, or a three-layer laminate in which other layers are inserted between the two nonwoven fabric layers of the present invention may be used. The method for bonding the layers is not particularly limited, and a needle punch method or a heat seal method may be employed, or lamination may be appropriately integrated using an adhesive. Of course, you may join and use another sheet | seat in the spreading direction of a nonwoven fabric. Further, other chemicals, treatment agents, resins, etc. may be applied and immersed depending on the purpose.
[0035]
The elastic wet sheet obtained according to the present invention is excellent in liquid absorption performance, hardly causes liquid drainage due to external stress, and is flexible and excellent in mechanical strength. Among them, it is suitable for liquid retaining materials, wiping materials, poultice base materials, vibration isolating materials, cushion materials, cold insulating materials, aromatic materials and the like.
In some cases, the elastic wet sheet of the present invention may be dried and / or heated to form a hard molded body (hard sheet or the like). Since such a hard molded body is excellent in mechanical performance and form stability, it can be used for any application. In particular, when the hard molded body is wetted again, it substantially returns to the state of the elastic wet sheet before drying. Therefore, the hard molded body is stored and transported as a hard molded body, and when the wet sheet becomes necessary, the hard molded body Can be moistened to obtain a desired elastic wet sheet. Since the wet molding can be dried again and the hardening process can be repeated many times, it can be used and stored very efficiently. The wet sheet may be dried at room temperature or may be dried at a high temperature. For example, it can be dried by leaving it in a dryer at 60 ° C. for 24 hours. Further, it may be formed into an arbitrary shape as desired. The liquid content of the hard molded body is preferably 5% by mass or less.
[0036]
【Example】
EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the examples.
[Intrinsic viscosity poise]
It was measured with a Tokyo Keiki B-type viscometer.
[Average polymerization degree of PVA]
Based on JIS K6726, it calculated by logP = 1.63log ([(eta)] * 104 / 8.29) from the measured value of intrinsic viscosity [(eta)] of 30 degreeC aqueous solution. P is the average degree of polymerization of PVA.
[0037]
[Fineness dtex]
It measured according to JIS-L-1015-7.5.1.
[Fiber strength cN / dtex]
It measured according to JIS-L-1095-7.5.1.
[Number of crimps / 25 mm, Crimp rate%, Residual crimp ratio%]
Measurements were made according to JIS-L-1015-7.12.1 and JIS-L-1015-7.12.2, respectively.
[0038]
[Fiber dissolution temperature in water ℃]
When the sample is immersed in water at 0 ° C. with a bath ratio of 1/100 and the water is heated at a rate of 2 ° C./min while stirring, the temperature at which the fiber is substantially completely dissolved is determined as the water dissolution temperature. It was. If possible, the fiber dissolution temperature in water may be measured in the form of a non-woven fabric.
[0039]
[Bulk density g / cm ^Three ]
The basis weight cut out to a size of 10cm x 10cm (A) g / m ² With respect to the sample, the thickness was measured at any 10 points according to JIS-L-1913, and this arithmetic average was defined as the average thickness (B) μm. Next, A was divided by B to calculate the bulk density of the sample.
When the size of the sample is smaller than 10 cm × 10 cm, each value is measured using the sample as it is without being cut out.
The bulk density during drying is a value obtained by drying the bulk density in a dryer at 60 ° C. for 24 hours and then obtaining the bulk density by the same method as described above.
[0040]
[Liquid content% by mass]
The sample (mass Ag) is subjected to centrifugal dehydration treatment at 3000 rpm × 10 minutes in a centrifugal dehydrator, and the sample after centrifugal dehydration treatment is further dried in a dryer at 105 ° C. for 2 hours to obtain the mass Bg of the sample. The liquid content was determined by (AB) / (A) × 100.
[Liquid absorption percentage by mass]
The liquid absorption rate was calculated according to JIS-L-1912 6.12.3.
[Swelling degree (retention rate) mass%, elution rate mass%]
In a standard laboratory according to JIS-Z-9703, water (water temperature 20 ± 2 ° C.) according to JIS-L-1015-7, 7.2, and sample (A) g in a bath ratio of 1/100 For 24 hours. Thereafter, the sample was taken out in the same test chamber, treated in a centrifugal dehydrator at 3000 rpm for 10 minutes, and then the mass B (g) of the sample was measured. Further, the sample after centrifugal dehydration was dried in a dryer at 105 ° C. for 2 hours, the mass C (g) was measured again, and the swelling degree and elution rate of the sample were calculated by the following formulas.
Swelling degree (mass%) = ((B) − (C)) / (C) × 100
Elution rate (mass%) = ((A) − (C)) / (A) × 100
[0041]
[Strength of wet sheet N / 25 mm, elongation%, breaking length km]
The wet sheet was measured according to JIS-L-1913-6.3, and the tear length was calculated by dividing the strength by the basis weight and the measured sample width. In addition, each value shall be calculated | required by measuring each about a length direction and a horizontal direction, and calculating this.
[0042]
[50% elongation recovery rate%]
B) For a wet sheet prepared according to JIS L 1913 6.3.2 b), a test piece having a width of 50 mm was gripped at a grip interval of 100 mm according to JIS L 1096, and pulled at a tensile speed of 100 mm / min. It is stretched to 50% of the degree and held for 1 minute, and this is returned to the original distance between chucks of 100 mm. Subsequently, it is pulled again so that the elongation becomes 50%, and this state is maintained for 1 minute. Repeat this process 5 times, measure the length (A) of the wet sheet when the process is completed 5 times, and recover the elongation (percentage) by dividing the length (B) of the wet sheet before the test by (A). Rated as a rate. In addition, the elongation recovery rate was calculated | required about the length direction and the horizontal direction, respectively, and the arithmetic average of this was calculated | required as a recovery rate.
[0043]
[Reference Example 1]
PVA having a polymerization degree of 1700 and a saponification degree of 98.5 mol%, and a PVA having a polymerization degree of 600 and a saponification degree of 73 mol% and a melting point of 173 ° C. were respectively 15% and 5% (polymer mass ratio 75 / 25) In a nitrogen atmosphere, it was added to DMSO at 90 ° C. to prepare a spinning dope having a PVA concentration of 20% by mass. This spinning stock solution was passed through a nozzle having a pore diameter of 0.08 mm and a pore number of 3000, and wet-spun into a methanol solidified solution at 4 ° C. so that PVA having a saponification degree of 73 mol% became sea-island structure fibers serving as island components. The obtained solidified yarn is subjected to wet stretching of 5.0 times, immersed in a methanol solution, extracted and washed with DMSO in the solidified yarn, dried and heated to 110 ° C. to give crimps. A raw cotton was produced by cutting to a fiber length of 51 mm.
The obtained fiber was a PVA fiber having a single fiber fineness of 1.3 dtex, a strength of 8.2 cN / dtex, a swelling degree of 212 mass%, a dissolution temperature in water of 74 ° C., and an elution rate of 1.43 mass%. Furthermore, the number of crimps of the crimped fiber was 8.8 pieces / 25 mm, the crimp rate was 8.6%, and the residual crimp rate was 46.1%.
[0044]
[Reference Example 2]
A PVA crimped fiber having a single fiber fineness of 3.3 dtex, a strength of 8.8 cN / dtex, a swelling degree of 220% by mass, a dissolution temperature in water of 77 ° C., and an elution of 1.36% by mass is produced in the same manner as described in Reference Example 1. did. The number of crimps of the crimped fiber was 7.8 pieces / 25 mm, the crimp rate was 8.2%, and the residual crimp rate was 42.5%.
[Reference Example 3]
A PVA raw material having a polymerization degree of 1700 and a saponification degree of 98.5 mol% was added to DMSO at 90 ° C. under a nitrogen atmosphere to prepare a spinning dope having a PVA concentration of 20 mass%. The spinning solution was wet-spun into a methanol solidified solution at 4 ° C. through a nozzle having a hole diameter of 0.08 mm and a hole number of 3000. The obtained solidified yarn is subjected to wet stretching of 5.0 times, immersed in a methanol solution, extracted and washed with DMSO in the solidified yarn, dried and heated to 110 ° C. to give crimps. A raw cotton was produced by cutting to a fiber length of 51 mm. The obtained fiber was a PVA fiber having a single fiber fineness of 1.3 dtex, a strength of 9.4 cN / dtex, a swelling degree of 36 mass%, a dissolution temperature in water of 87 ° C., and an elution rate of 0.25 mass%. Further, the number of crimps of the crimped fiber was 9.1 pieces / 25 mm, the crimp rate was 8.5%, and the residual crimp rate was 48.6%.
[0045]
[Reference Example 4]
A PVA raw material having a polymerization degree of 1700 and a saponification degree of 93.5 mol% was added to DMSO at 90 ° C. under a nitrogen atmosphere to prepare a spinning dope having a PVA concentration of 20 mass%. The spinning solution was wet-spun into a methanol solidified solution at 4 ° C. through a nozzle having a hole diameter of 0.08 mm and a hole number of 3000. The obtained solidified yarn is subjected to wet stretching of 5.0 times, immersed in a methanol solution, extracted and washed with DMSO in the solidified yarn, dried and heated to 110 ° C. to give crimps. A raw cotton was produced by cutting to a fiber length of 51 mm.
The obtained fiber was a PVA fiber having a single fiber fineness of 1.3 dtex, a strength of 5.4 cN / dtex, a dissolution temperature in water of 31 ° C., and an elution rate of 100% by mass. Furthermore, the number of crimps of the crimped fiber was 8.5 pieces / 25 mm, the crimp rate was 8.3%, and the residual crimp rate was 52.6%. The degree of swelling was not measurable because the solubility in water was too high.
[0046]
[Example 1]
The raw cotton obtained in Reference Example 1 is passed through a parallel card process (Teccaine 150 rpm, cylinder 250 rpm, doffer 7 rpm), and the basis weight is 150 g / m. ² The web was manufactured. Next, the needle punching process was performed on both sides of the web with a needle having a kick defect and a needle pub number of 9 and a blade diameter of 0.55 mm. The needle punch number was 350 / cm. ² , Basis weight 150g / m ² , Bulk density 0.118 g / cm ^Three An intertwined nonwoven fabric was produced.
[0047]
Subsequently, 20 degreeC water was provided to this nonwoven fabric, and the elastic wet sheet | seat was manufactured. The performance of the wet sheet is shown in Table 1. The obtained elastic wet sheet was difficult to drain even when external pressure was applied, and was excellent in liquid retention. Moreover, it has excellent mechanical strength and has a high degree of flexibility and elasticity as well as a pleasing tactile sensation, making it suitable as a wiping material, liquid retaining material, and the like.
Further, when the wet sheet was dried at 60 ° C. for 24 hours, it was rigid, excellent in mechanical performance and shape stability, and suitable for storage and transportation (bulk density 0.21 g / cm ^Three )was gotten. When the hard sheet was again absorbed, a wet elastic sheet similar to that before drying was obtained. The wet elastic sheet had a liquid absorption rate of 507% by mass and a liquid retention rate of 234% by mass, and no problem occurred even after repeated drying and wetting.
[0048]
[Example 2]
After blending the polyvinyl alcohol raw cotton obtained in Reference Example 1 and the rayon raw cotton (Corona CD fineness 1.5 dtex, fiber length 44 mm) manufactured by Daiwabo Co., Ltd. in a mass ratio of 75% / 25%, the parallel card process (Tecine 150 rpmm, cylinder) 250 rpm, doffer 7 rpm) and a basis weight of 200 g / m ² The web was manufactured. Next, a needle punching process was applied to both surfaces of the web with a needle having a kick defect, a needle pub number of 9 and a blade diameter of 0.55 mm. The needle punch number was 400 / cm. ² , Basis weight 200g / m ² , Bulk density 0.133 g / cm ^Three An intertwined nonwoven fabric was produced.
[0049]
Subsequently, 20 degreeC water was provided to this nonwoven fabric, and the elastic wet sheet | seat was manufactured. The performance is shown in Table 1. The obtained elastic wet sheet was difficult to drain even when external pressure was applied, and was excellent in liquid retention. Moreover, it has excellent mechanical strength and has a high degree of flexibility and elasticity as well as a pleasing tactile sensation, making it suitable as a wiping material, liquid retaining material, and the like.
Further, when the wet sheet was dried at 60 ° C. for 24 hours, it was rigid and excellent in mechanical performance and shape stability, and was suitable for storage and transportation (bulk density 0.18 g / cm ^Three )was gotten. When the hard sheet was again absorbed, a wet elastic sheet similar to that before drying was obtained. The wet elastic sheet had a liquid absorption rate of 546% by mass and a liquid retention rate of 266% by mass, and no problem occurred even when drying and wetting were repeated.
[0050]
[Example 3]
The raw cotton obtained in Reference Example 1 is passed through a parallel card process (Teccaine 150 rpm, cylinder 250 rpm, doffer 7 rpm), and the basis weight is 100 g / m. ² The web was manufactured. Next, a water flow pressure of 50 kg / cm is used on both surfaces of the web by using a water nozzle having a nozzle diameter of 0.1 mm, a pitch of nozzle holes of 0.6 mm, and two rows of holes. ² , Water entanglement treatment is performed at a water temperature of 26 ° C., and the basis weight is 100 g / m. ² , Bulk density 0.168 g / cm ^Three A non-woven fabric was produced.
Subsequently, 20 degreeC water was provided to this nonwoven fabric, and the elastic wet sheet | seat was manufactured. The performance is shown in mark 1. The obtained elastic wet sheet was difficult to drain even when external pressure was applied, and was excellent in liquid retention. Moreover, it has excellent mechanical strength and has a high degree of flexibility and elasticity as well as a pleasing tactile sensation, making it suitable as a wiping material, liquid retaining material, and the like.
Further, when the wet sheet was dried at 60 ° C. for 24 hours, it was rigid, excellent in mechanical performance and shape stability, and suitable for storage and transportation (bulk density 0.20 g / cm ^Three )was gotten. When the hard sheet was again absorbed, a wet elastic sheet similar to that before drying was obtained. The wet elastic sheet had a liquid absorption rate of 650% by mass and a liquid retention rate of 400% by mass, and no problem occurred even after repeated drying and wetting.
[0051]
[Example 4]
The raw cotton obtained in Reference Example 1 and a composite polyester crimped fiber PN720 manufactured by Kuraray Co., Ltd. (core-sheath structure, the sheath is isophthalic acid-modified polyester, the core is a polyester fiber, and the core-sheath ratio is 50/50 mass. %, Fineness 2.2 dtex, fiber length 51 mm) at a mass ratio of 85/15% by mass, and then passed through a parallel card process (Takein 150 rpmm, cylinder 250 rpm, doffer 7 rpm) to give a basis weight of 75 g / m. ² The web was manufactured. Next, one is heated to 125 ° C., the crimping area is 25% by area, and the number of crimping parts is 50 / cm. ² The fabric web was inserted between a metal roll having a concavo-convex surface and a metal roll heated to 125 ° C. with no concavo-convex surface, and was continuously thermocompression-bonded at a pressure of 400 N / cm. / m ² , Bulk density 0.260 g / cm ^Three A non-woven fabric was obtained. At this time, the time required for each fiber to be thermocompression bonded was 0.15 seconds.
Subsequently, 20 degreeC water was provided to this nonwoven fabric, and the elastic wet sheet | seat was manufactured. The performance of the wet sheet is shown in Table 1. The obtained elastic wet sheet was difficult to drain even when external pressure was applied, and was excellent in liquid retention. Moreover, it has excellent mechanical strength and has a high degree of flexibility and elasticity as well as a pleasing tactile sensation, making it suitable as a wiping material, liquid retaining material, and the like.
Further, when the wet sheet was dried at 60 ° C. for 24 hours, it was rigid and excellent in mechanical performance and shape stability, and was suitable for storage and transportation (bulk density 0.18 g / cm ^Three )was gotten. When the hard sheet was again absorbed, a wet elastic sheet similar to that before drying was obtained. The wet elastic sheet had a liquid absorption rate of 600% by mass and a liquid retention rate of 300% by mass, and no problem occurred even after repeated drying and wetting.
[0052]
[Comparative Example 1]
The PVA raw cotton described in Reference Example 2 is used, and the basis weight is 100 g / m by passing through a parallel card process (Teccaine 150 rpm, cylinder 250 rpm, doffer 7 rpm). ² The web was manufactured. Next, between a flat metal roll without an uneven surface heated to 205 ° C. and a rubber roll without an uneven surface heated to 105 ° C. by heat transfer from the previous metal flat roll. The fiber web was inserted into the base, and the basis weight was 75 g / m continuously thermocompression bonded at a pressure of 400 N / cm. ² , Density 0.528 g / cm ^Three A non-woven fabric was obtained. At this time, the time required for the thermocompression bonding of the fiber was 0.15 seconds.
Next, 20 ° C. water was applied to the paper to produce an elastic wet sheet. The performance of the wet sheet is shown in Table 1. The resulting elastic wet sheet has a large bulk density when dried and the size of the inter-fiber gap is too small, so that the fiber cannot sufficiently absorb and swell water, and therefore has excellent mechanical performance. Inferior to that of the present invention, the crisp feel was poor, and the liquid absorption rate and the liquid retention rate were small as compared with the Examples.
[0053]
[Comparative Example 2]
A basis weight of 150 g / m was obtained in the same manner as in Example 1 except that the PVA raw cotton of Reference Example 3 was used. ² , Bulk density 0.078 g / cm ^Three A non-woven fabric was produced.
Subsequently, 20 degreeC water was provided to this nonwoven fabric, and the wet sheet | seat was manufactured. The liquid content and the liquid retention rate of the wet sheet obtained due to insufficient liquid retention capacity of the fibers used are as small as 38% by mass, and the performance as a liquid retention material is insufficient. The mechanical performance of the wet sheet was low, and no tactile sensation was exhibited.
[0054]
[Comparative Example 3]
A basis weight of 150 g / cm is obtained in the same manner as in Example 1 except that the PVA raw cotton of Reference Example 4 is used. ² , Bulk density 0.078 g / cm ^Three A non-woven fabric was produced. Next, an attempt was made to obtain an elastic wet sheet by applying 20 ° C. water to the nonwoven fabric. However, since the water dissolution temperature of the PVA fiber is low, the fiber can be eluted and the sheet shape can be maintained. In addition, a wet sheet excellent in liquid retention, elasticity, mechanical performance and the like was not obtained.
[0055]
[Table 1]

Claims (7)

An elastic wet sheet comprising a nonwoven fabric containing 50% by mass or more of a liquid having a temperature of 50 ° C. or less, 50% elongation recovery rate 60% or more, tearing length 3 km or more, liquid retention rate 100 to 500%, when dried 30% by mass or more of the fibers constituting the sheet having a bulk density of 0.5 g / cm ³ or less are polyvinyl alcohol fibers having a dissolution temperature in water of 60 ° C. or more, and the polyvinyl alcohol fibers have a saponification degree of 98. An elastic wet sheet having a sea-island structure in which a vinyl alcohol polymer of mol% or more is a sea component and a vinyl alcohol polymer having a saponification degree of 97 mol% or less is an island component. An elastic wet sheet obtained by impregnating a nonwoven fabric having a bulk density of 0.5 g / cm ³ or less with a liquid having a temperature of 50 ° C. or less at 50% by mass or more, wherein 30% by mass or more of the fibers constituting the nonwoven fabric are dissolved in water. A polyvinyl alcohol fiber having a temperature of 60 ° C. or higher, and the polyvinyl alcohol fiber having a saponification degree of 98 mol% or more as a sea component and a vinyl alcohol polymer having a saponification degree of 97 mol% or less as an island component An elastic wet sheet having a sea-island structure. A hard molded body obtained by drying and / or heating the elastic wet sheet according to claim 1. The manufacturing method of the hard molding which dries and / or heats the elastic wet sheet | seat of Claim 1 or Claim 2. A method for producing a wet elastic sheet, wherein the hard molded body according to claim 3 contains 50% by mass or more of a liquid having a temperature of 50 ° C. or lower. A liquid retaining material using the elastic wet sheet according to claim 1. A wiping material obtained using the elastic wet sheet according to claim 1.