WO2014084253A1 - Sheet-shaped object and process for producing said sheet-shaped object - Google Patents

Abstract

The present invention provides a process for producing a sheet-shaped object which has a piled graceful appearance and a soft texture and which has even better wear resistance, the process being characterized in that the following steps (1) to (5) are conducted sucessively. (1) A step in which a polyvinyl alcohol having a degree of saponification of 98% or higher and a degree of polymerization of 800-3,500 is dissolved in water to obtain an aqueous polyvinyl alcohol solution in which the contents of methyl acetate, acetic acid, and methanol are 50 ppm or less each; (2) a step in which the polyvinyl alcohol is imparted to a fibrous base that comprises, as the main constituent component, fibers capable of forming ultrafine fibers, in an amount of 0.1-50 mass% relative to the fibers of the fibrous base; (3) a step in which ultrafine fibers having an average single-fiber diameter of 0.3-7 μm are formed from the fibrous base obtained in the step (2); (4) a step in which a water dispersion type polyurethane is imparted to the fibrous base obtained in the step (3); and (5) a step in which the polyvinyl alcohol is removed from the fibrous base obtained in the step (4).

Description

Sheet material and method for producing the sheet material

The present invention reduces the amount of organic solvent used in the manufacturing process by using water-dispersed polyurethane as the binder resin, and in an environmentally friendly sheet-like material, achieves both good flexibility and high-grade appearance quality, The present invention also relates to a sheet-like material having good wear resistance and a method for producing the sheet-like material.

A sheet-like material mainly composed of a fibrous base material and polyurethane has excellent characteristics not found in natural leather and is widely used for various applications. In particular, a leather-like sheet-like material using a polyester-based fibrous base material is excellent in light resistance, and therefore its use has been expanded year by year for clothing, chair upholstery, automobile interior materials, and the like.

In manufacturing such a sheet-like material, after impregnating a fibrous base material with an organic solvent solution of polyurethane, the obtained fibrous base material is mixed with water which is a non-solvent of polyurethane or an organic solvent / water mixed solution. A process in which the polyurethane is wet-solidified by dipping in it is generally employed. As the organic solvent that is a solvent for such polyurethane, a water-miscible organic solvent such as N, N-dimethylformamide (hereinafter also referred to as “DMF”) is used. PVA "is also obtained.) A fiber sheet is obtained by impregnating with an aqueous solution, the fiber sheet is immersed in a polyurethane impregnating solution, and the polyurethane is wet coagulated in a 45% DMF aqueous solution at 20 ° C. There has been proposed a method for producing a sheet by removing DMF and polyvinyl alcohol with hot water at 85 ° C. (see Patent Document 1). However, since organic solvents are generally highly harmful to the human body and the environment, there is a strong demand for methods that do not use organic solvents in the production of sheet-like materials.

As a specific solution, for example, a method using water-dispersed polyurethane in which polyurethane is dispersed in water instead of the conventional organic solvent type polyurethane has been studied. However, the fibrous base material impregnated with water-dispersible polyurethane and imparted has a problem that the texture becomes hard. The main factor of this problem is that polyurethane adheres strongly to the fibers of the fibrous base material. As a study to solve such problems, as in the manufacturing process using conventional organic solvent type polyurethane, in order to partially inhibit the adhesion between the fiber and polyurethane, to create a gap between the fiber and polyurethane. In addition, a method has been proposed in which PVA is applied to a fibrous base material in advance, then polyurethane is applied, and then PVA is removed (see Patent Document 2).

Here, since PVA is water-soluble, when PVA is applied to the fibrous base material and then wetted with water, PVA dissolves and falls off, so that the dissolution and dropping of PVA in the process of soaking in water is suppressed. Therefore, in patent document 2, the following means are employ | adopted in (i) the ultrafine process of the fiber by aqueous alkali solution, and (ii) the impregnation process of water dispersion type polyurethane. That is, dropping of the former fiber in the ultrafine process is suppressed by adding borax to the alkaline aqueous solution, while the latter water-dispersed polyurethane impregnation process has a saponification degree of 98% and By using PVA having a polymerization degree of 500, dropping of PVA into water is suppressed. However, with regard to the effect of adding borax in the fiber ultrafine process, it takes a long time to soak the fiber in the alkaline aqueous solution, so even if borax is added to the alkaline aqueous solution, it is completely added to the water. The dissolution of PVA cannot be suppressed. In addition, regarding the impregnation step of water-dispersed polyurethane, since the degree of polymerization of PVA is low, dissolution in water cannot be completely suppressed, and dropping into water-dispersed polyurethane liquid cannot be suppressed. Due to the dissolution of PVA in the type polyurethane liquid, there was a problem that the adhesive state between the polyurethane and the fiber could not be stably controlled, and the texture of the sheet-like material became hard.

In addition, to solve the problems in the steps (i) and (ii) above, the PVA having a saponification degree of 90% or more is given to the nonwoven fabric sheet, and the PVA is dissolved in water by heating at 150 to 195 ° C. A method of reducing the property has been proposed (see Patent Document 3). By heating at a high temperature, the intermolecular hydrogen bond of PVA is strengthened and the solubility in water is lowered. However, if the temperature is too high or the heating time is too long, PVA becomes insoluble and dissolves in water. Since re-dissolution is difficult, there is a problem that it is difficult to stabilize appropriate conditions.

JP 2002-30579 A JP 2003-096676 A Japanese Patent No. 4644971

The present invention relates to an environmentally friendly sheet-like manufacturing method that reduces the use of organic solvents in the manufacturing process, and provides a sheet that has both an elegant appearance with napping and a soft texture and has good wear resistance. The present invention provides a method for producing a sheet and a sheet obtained by the production method.

That is, the sheet-like material manufacturing method of the present invention is characterized in that the following steps 1 to 5 are sequentially performed.
1. A step of dissolving polyvinyl alcohol having a saponification degree of 98% or more and a polymerization degree of 800 to 3500 in water to obtain a polyvinyl alcohol aqueous solution having a concentration of methyl acetate, acetic acid or methanol of 50 ppm or less,
2. By applying the aqueous polyvinyl alcohol solution to a fibrous base material containing an ultrafine fiber-expressing fiber as a main constituent, the polyvinyl alcohol is added in an amount of 0.1 to 50% by mass with respect to the fiber mass contained in the fibrous base material The step of applying,
3. A step of expressing an ultrafine fiber having an average single fiber diameter of 0.3 to 7 μm from a fibrous base material having an ultrafine fiber expression type fiber as a main constituent component;
4). A step of imparting water-dispersible polyurethane to a fibrous base material comprising, as a main constituent, ultrafine fibers to which the polyvinyl alcohol has been imparted,
5. A step of removing polyvinyl alcohol from a fibrous base material comprising, as a main constituent, ultrafine fibers provided with the water-dispersed polyurethane.
According to a preferred embodiment of the method for producing a sheet-like material of the present invention, the production method includes a step of obtaining an aqueous polyvinyl alcohol solution having methyl acetate, acetic acid, and methanol concentrations of 0.1 to 50 ppm, respectively.
According to the preferable aspect of the manufacturing method of the sheet-like material of this invention, the process of expressing an ultrafine fiber is a process processed with alkaline aqueous solution.
According to a preferred aspect of the method for producing a sheet-like material of the present invention, the production method includes a step of applying the polyvinyl alcohol and heating at 80 to 170 ° C.
According to a preferred aspect of the method for producing a sheet-like product of the present invention, the fibrous base material containing the ultrafine fiber-expressing fiber as a main constituent component is intertwined with the woven fabric and / or the knitted fabric.
Further, the density of the obtained sheet-like material is preferably 0.2 to 0.7 g / cm ³ .

According to the present invention, even in an environmentally-friendly manufacturing process, an elegant appearance and a flexible texture that could not be achieved in the past can be achieved, and a sheet-like product having better wear resistance can be obtained. Can do.

The sheet-like material manufacturing method of the present invention is characterized in that the following steps 1 to 5 are performed in this order.
1. A step of dissolving polyvinyl alcohol having a saponification degree of 98% or more and a polymerization degree of 800 to 3500 in water to obtain a polyvinyl alcohol aqueous solution having a concentration of methyl acetate, acetic acid or methanol of 50 ppm or less,
2. By applying the aqueous polyvinyl alcohol solution to a fibrous base material containing an ultrafine fiber-expressing fiber as a main constituent, the polyvinyl alcohol is added in an amount of 0.1 to 50% by mass with respect to the fiber mass contained in the fibrous base material. The step of applying,
3. A step of expressing an ultrafine fiber having an average single fiber diameter of 0.3 to 7 μm from a fibrous base material having an ultrafine fiber expression type fiber as a main constituent component;
4). A step of imparting water-dispersible polyurethane to a fibrous base material comprising, as a main constituent, ultrafine fibers to which the polyvinyl alcohol has been imparted,
5. A step of removing polyvinyl alcohol from a fibrous base material comprising, as a main constituent, ultrafine fibers provided with the water-dispersed polyurethane.

In the method for producing a sheet-like product of the present invention, it is important to perform the steps 1 to 5 in this order. After application of an aqueous solution of polyvinyl alcohol (also referred to as PVA) having a degree of saponification of 98% or more and a degree of polymerization of 800 to 3500 to a fibrous base material containing an ultrafine fiber expression type fiber as a main constituent, Then, a process (desealing process) for expressing ultrafine fibers is performed, and then a water-dispersed polyurethane liquid is applied to a fibrous base material containing the ultrafine fibers provided with PVA as a main constituent, and further from the fibrous base material. By removing PVA, large voids derived from PVA and sea components are generated between the fiber and polyurethane, and the polyurethane directly grips the ultrafine fibers, so that it has good appearance and soft texture It is possible to express physical characteristics such as wear resistance.

In addition, when a PVA aqueous solution is applied to a fibrous base material and dried by heating, a so-called migration phenomenon occurs in which the PVA in the water is attracted by the movement of the water and concentrates on the surface layer of the fibrous base material. A large amount adheres to the surface layer of the material and a small amount adheres to the inner layer. By migrating PVA, the water-dispersed polyurethane to be applied thereafter adheres mainly to the inner layer of the fibrous base material. And when PVA is removed, in the vicinity of the surface layer of the fibrous base material to which a large amount of PVA has adhered, a large gap is formed between the fiber and the polyurethane, and the surface appearance of the sheet-like material that has undergone the napping process becomes a bundle. An elegant appearance that is evenly distributed.

On the other hand, when sea removal treatment is performed after PVA removal, both voids resulting from the removal of PVA and voids resulting from sea components removed from seawater are generated between polyurethane and ultrafine fibers. The area directly gripped by the polyurethane is further reduced, and the texture of the sheet-like material becomes flexible, but physical properties such as wear resistance tend to deteriorate.

[First step]
First, PVA having a saponification degree of 98% or more and a polymerization degree of 800 to 3500 in the first step is dissolved in water, and a PVA aqueous solution having a concentration of methyl acetate, acetic acid, and methanol of 50 ppm or less is obtained. The process to obtain is described.

Methyl acetate, acetic acid, and methanol are substances that are produced in the process of increasing the degree of saponification from polyvinyl acetate, which is a precursor of PVA synthesis, and also due to decomposition of residual polyvinyl acetate that has not been sufficiently saponified It is a substance to be generated. Since methyl acetate, acetic acid, and methanol each have a concentration of 50 ppm or less of methyl acetate, acetic acid, and methanol in the PVA aqueous solution, PVA intermolecular hydrogen bonds are easily formed during heating and drying, and water (including hot water), acid, The solubility of PVA in the aqueous alkali solution can be suppressed. In addition, since the PVA intermolecular hydrogen bond is easily formed, the heat drying temperature can be set to a relatively low temperature of 80 to 140 ° C., so that the thermal decomposition of PVA can be suppressed. The concentration of methyl acetate, acetic acid, and methanol in the PVA aqueous solution is more preferably 0.1 to 50 ppm, respectively, and the presence of trace amounts of methyl acetate, acetic acid, and methanol makes them weakly hydrogen bond with the PVA molecule. Thus, the distance between PVA molecules is reduced, and hydrogen bonds between PVA molecules are easily formed. If the concentrations of methyl acetate, acetic acid, and methanol are too high, the formation of PVA intermolecular hydrogen bonds is inhibited, so that the more preferable concentration is 0.3 to 40 ppm, and further preferably 5 to 40 ppm.

The concentration of methyl acetate, acetic acid, and methanol in the PVA aqueous solution is analyzed as follows. 1 g of PVA aqueous solution is put into a 24 mL heating tube and heated at 90 ° C. for 1 hour. From the heating tube, 0.1 mL of the generated gas is collected with a gas tight syringe and introduced into GC / MS (mass spectrometer directly connected to a gas chromatograph) for analysis.

In order to reduce the concentration of methyl acetate, acetic acid, and methanol in the aqueous PVA solution, use PVA that generates little methyl acetate, acetic acid, and methanol during heating of the PVA itself before making the aqueous solution, or prepare the aqueous PVA solution In this case, the heating time for raising the temperature for dissolving PVA in water may be lengthened. As for the former, the higher the degree of saponification, the lower the generation amount of methyl acetate, acetic acid and methanol. Therefore, it is preferable to use 98% or higher high saponification degree PVA. In the latter case, if the temperature rise is too low, methyl acetate, acetic acid and methanol cannot be sufficiently removed. Therefore, the temperature is preferably 80 to 100 ° C. If the heating time is too short, methyl acetate, acetic acid and methanol cannot be sufficiently removed. Therefore, one hour or more is preferable. Note that methyl acetate, acetic acid, and methanol may be completely removed from the PVA aqueous solution.

In the embodiment of the present invention, the PVA applied to the fibrous base material has a saponification degree of 98% or more and a polymerization degree of 800 to 3500. By setting the saponification degree of PVA to 98% or more, it is possible to prevent the PVA from being dissolved in the water-dispersed polyurethane liquid when the water-dispersed polyurethane is applied. When PVA is dissolved in the water-dispersed polyurethane liquid, not only is the effect sufficient to protect the surface of the ultrafine fibers constituting napped fibers, but also the water-dispersed polyurethane liquid in which PVA is dissolved is used as a fibrous base. When it is applied to the material, PVA is taken into the polyurethane and it becomes difficult to remove the PVA later. Therefore, the adhesive state between the polyurethane and the fibers cannot be stably controlled, and the texture becomes hard.

Also, the solubility of PVA in water varies depending on the degree of polymerization. The smaller the degree of polymerization of PVA, the more PVA dissolves in the water-dispersed polyurethane liquid when the water-dispersed polyurethane is applied. The higher the degree of polymerization of PVA, the higher the viscosity of the PVA aqueous solution, and when impregnating the fibrous base material with the PVA aqueous solution, PVA cannot penetrate into the fibrous base material. Is from 1000 to 3000, more preferably from 1200 to 2500.

In the present invention, PVA preferably has a viscosity of 10 to 70 mPa · s at 20 ° C. in a 4% by mass aqueous solution. When the viscosity of PVA is within this range, an appropriate migration structure can be obtained inside the fibrous base material during drying, and a balance of physical properties such as flexibility, surface appearance, and abrasion resistance of the sheet-like material is obtained. It is done. By setting the viscosity to 10 mPa · s or more, more preferably 15 mPa · s or more, an extreme migration structure can be suppressed. On the other hand, by setting the viscosity to 70 mPa · s or less, more preferably 50 mPa · s or less, and even more preferably 40 mPa · s or less, the fibrous base material can be easily impregnated with PVA.

In the present invention, the glass transition temperature (Tg) of PVA is preferably 70 to 100 ° C. By setting the glass transition temperature of PVA to 70 ° C. or higher, more preferably 75 ° C. or higher, softening in the drying process can be prevented, dimensional stability of the fibrous base material can be obtained, and the surface appearance of the sheet-like product can be improved. Deterioration can be suppressed. Further, by setting the glass transition temperature to 100 ° C. or lower, more preferably 95 ° C. or lower, it is possible to prevent the handling property from deteriorating due to the fibrous base material becoming too hard.

In the present invention, the melting point of PVA is preferably 200 to 250 ° C. By setting the melting point of PVA to 200 ° C. or more, more preferably 210 ° C. or more, softening in the drying process can be prevented, dimensional stability of the fibrous base material can be obtained, and the surface appearance of the sheet-like material is deteriorated. Can be suppressed. Further, by setting the melting point of PVA to 250 ° C. or lower, more preferably 240 ° C. or lower, it is possible to prevent the handling property from deteriorating due to the fibrous base material becoming too hard.

In the present invention, the tensile strength of the PVA film is preferably 400 to 800 kg / cm ² . By setting the tensile strength of the PVA film to 400 kg / cm ² or more, more preferably 450 kg / cm ² or more, it is possible to suppress dimensional changes during handling and suppress deterioration of the surface appearance of the sheet-like material. By setting the tensile strength of the PVA film to 800 kg / cm ² or less, more preferably 750 kg / cm ² or less, the PVA-applied sheet does not become too hard, and the occurrence of creasing and the like during handling can be suppressed. Here, the tensile strength is a value obtained by measuring a 100 μm thick PVA film in an atmosphere at a temperature of 20 ° C. and a humidity of 65%.

[Second step]
Next, by applying a PVA aqueous solution to a fibrous base material having an ultrafine fiber-expressing fiber as a main component, which is the second step, the PVA is reduced to 0. 0 relative to the fiber mass contained in the fibrous base material. The step of applying 1 to 50% by mass will be described.

The fibrous base material of the present invention is mainly composed of ultrafine fiber expression type fibers. By using the ultrafine fiber expression type fiber, the fiber can be made ultrafine by passing through the subsequent ultrafine fiber process, and an elegant surface appearance can be obtained.

In a preferred embodiment of the present invention, the average single fiber diameter of the ultrafine fiber obtained from the ultrafine fiber expression type fiber through the fiber ultrafine process is 0.3 to 7 μm. By setting the average single fiber diameter to 7 μm or less, more preferably 6 μm or less, and even more preferably 5 μm or less, it is possible to obtain a sheet-like product having excellent flexibility and napping quality. On the other hand, by setting the average single fiber diameter to 0.3 μm or more, more preferably 0.7 μm or more, and even more preferably 1 μm or more, the bundle of fibers at the time of napping such as coloring after dyeing or grinding with sandpaper is used. Excellent dispersibility and ease of handling.

As the ultrafine fiber-expressing type fiber, (a) a two-component thermoplastic resin having different solvent solubility is used as a sea component and an island component, and the sea component is dissolved and removed using a solvent or the like to remove the island component from the ultrafine fiber. Adopting sea-island type fibers and (b) peelable composite fibers that split two components of thermoplastic resin radially or in multiple layers on the fiber cross section and split each component into ultrafine fibers. can do. Among these, the sea-island type fibers can be preferably used also from the viewpoint of the flexibility and texture of the sheet-like material because an appropriate void can be imparted between the island components, that is, between the ultrafine fibers, by removing the sea components. .

As the sea-island type fiber, for example, a sea-island type composite base is used, and a sea-island type composite fiber in which two components of the sea component and the island component are arranged and spun together; There are mixed spinning fibers. Sea-island type composite fibers are preferably used from the viewpoint that ultrafine fibers having a uniform fineness can be obtained, and that a sufficiently long ultrafine fiber is obtained and contributes to the strength of the sheet-like material.

The island component of the sea-island fiber is not particularly limited. For example, polyesters such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate and polylactic acid; polyamides such as 6-nylon and 66-nylon; acrylics; polyethylenes; polypropylenes And fibers made of melt-spinnable thermoplastic resin such as thermoplastic cellulose can be used. Among these, polyester fibers are preferably used from the viewpoints of strength, dimensional stability, and light resistance. Further, from the viewpoint of environmental consideration, fibers obtained from recycled raw materials and plant-derived raw materials are preferable. Furthermore, the fibrous base material may be configured by mixing fibers of different materials.

The sea component of the sea-island fiber is not particularly limited, and for example, polyethylene; polypropylene; polystyrene; copolymer polyester obtained by copolymerization with sodium sulfoisophthalate or polyethylene glycol, and polylactic acid; PVA can be used. Of these, from the viewpoint of environmental considerations, a copolyester or polylactic acid obtained by copolymerizing alkali-decomposable sodium sulfoisophthalate or polyethylene glycol that can be decomposed without using an organic solvent, and hot water-soluble PVA are preferable. .

The cross-sectional shape of the fiber constituting the fibrous base material is not particularly limited, and may be a round cross-section, but adopts a polygonal shape such as an ellipse, a flat shape, and a triangular shape, or a deformed cross-section shape such as a sector shape and a cross shape. Also good.

In the present invention, the average single fiber diameter of the fibers constituting the fibrous base material is preferably 0.3 to 20 μm. The thinner the average single fiber diameter is, the better the flexibility and napping quality of the sheet can be obtained.On the other hand, the thicker the average single fiber diameter is, the thicker the bundle is at the time of napping treatment such as coloring after dyeing or grinding with sandpaper. From the viewpoint of excellent dispersibility and ease of spreading of the fibrous fibers, the thickness is more preferably 0.7 to 15 μm, particularly preferably 1 to 7 μm.

The woven fabric, knitted fabric, non-woven fabric and the like can be adopted as the form of the fibrous base material of the present invention. Especially, since the surface appearance of the sheet-like material at the time of surface raising treatment is favorable, a nonwoven fabric is preferably used.

The non-woven fabric may be either a short-fiber non-woven fabric or a long-fiber non-woven fabric, but the long-fiber non-woven fabric has fewer fibers facing the thickness direction of the sheet-like material when raised, than the short-fiber non-woven fabric. Is low and the surface appearance tends to be inferior, short fiber nonwoven fabrics are preferably used.

The fiber length of the short fiber in the short fiber nonwoven fabric is preferably 25 to 90 mm. By setting the fiber length to 25 mm or more, a sheet-like material having excellent abrasion resistance can be obtained by entanglement. In addition, when the fiber length is 90 mm or less, a sheet-like material having excellent texture and quality can be obtained. The fiber length is more preferably 30 to 80 mm.

Needle punch or water jet punch can be employed as a method of entanglement of non-woven fibers or fiber bundles.

In the present invention, when the fibrous base material made of ultrafine fibers is a non-woven fabric, it is a preferred embodiment that the non-woven fabric has a structure in which bundles of ultrafine fibers (ultrafine fiber bundles) are intertwined. Since the ultrafine fibers are entangled in a bundle state, the strength of the sheet-like material is improved. The nonwoven fabric of such an embodiment can be obtained by causing the ultrafine fibers to develop after entanglement of the ultrafine fiber-expressing fibers in advance.

When the ultrafine fiber or the ultrafine fiber bundle constitutes a non-woven fabric, it may be intertwined with the woven fabric or the knitted fabric for the purpose of improving the strength. For example, in the case of a woven fabric, plain weave, twill weave, satin weave, etc. are mentioned, and plain weave is preferably used from the viewpoint of cost. In the case of a knitted fabric, circular knitting, tricot, Russell and the like can be mentioned. The average single fiber diameter of the fibers constituting the woven or knitted fabric is preferably 0.3 to 20 μm.

As a preferable aspect of the present invention, when a woven fabric and / or a knitted fabric are intertwined and integrated inside a fibrous base material containing an ultrafine fiber-expressing fiber as a main component, it is applied thereafter by applying PVA. The water-dispersible polyurethane reduces the area for directly holding the woven fabric and / or knitted fabric, and the texture of the sheet-like material can be softened. In particular, the woven fabric and / or knitted fabric is composed of fibers that are not very fine fiber expression type fibers. A significant softening effect is obtained.

The amount of PVA applied to the fibrous base material is 0.1 to 50% by mass, preferably 1 to 45% by mass, based on the fiber mass of the fibrous base material. By making the application amount of PVA 0.1% by mass or more, a sheet-like material having good flexibility and texture can be obtained, and by making the application amount of PVA 50% by mass or less, workability is good and resistance is improved. A sheet-like material having good physical properties such as wear is obtained.

In the present invention, the method for imparting PVA to the fibrous base material is not particularly limited, and various methods commonly used in this field can be adopted. However, PVA is dissolved in water, impregnated into the fibrous base material, and dried by heating. The method to do is preferable from a viewpoint which can provide uniformly. If the drying temperature is too low, a long drying time is required. If the drying temperature is too high, the PVA is insolubilized and cannot be dissolved and removed later. The temperature is more preferably 110 to 130 ° C. The drying time is usually 1 to 20 minutes, preferably 1 to 10 minutes, more preferably 1 to 5 minutes from the viewpoint of processability. Moreover, in order to insolubilize PVA more, you may heat-process after drying. A preferable temperature for the heat treatment is 80 to 170 ° C. By heat treatment, insolubilization of PVA and thermal degradation of PVA proceed at the same time, so a more preferable temperature is 80 to 140 ° C.

[Third step]
Next, the third step of expressing ultrafine fibers having an average single fiber diameter of 0.3 to 7 μm from a fibrous base material containing ultrafine fiber expression type fibers as the main constituent components will be described.

The fiber ultrafine treatment (desealing treatment) of the fibrous base material containing the ultrafine fiber expression type fiber as the main constituent can be performed by immersing the fibrous base material in a solvent and squeezing. When the ultrafine fiber-expressing fiber is a sea-island fiber, when the sea component is polyethylene, polypropylene, or polystyrene, an organic solvent such as toluene or trichlorethylene is used, and when the sea component is a copolyester or polylactic acid An alkaline aqueous solution such as sodium hydroxide can be used. Further, when the sea component is PVA, hot water can be used. From the viewpoint of environmental considerations of the process, a sea removal treatment with an aqueous alkali solution such as sodium hydroxide or hot water is preferable.

[Fourth step]
Next, a step of applying water-dispersed polyurethane to a fibrous base material having a main component of ultrafine fibers provided with PVA, which is a fourth step, will be described.

The water-dispersed polyurethane includes (I) a forced emulsification type polyurethane forcibly dispersed and stabilized in water using a surfactant, and (II) a surfactant having a hydrophilic structure in the molecular structure. Although it is classified as a self-emulsifying type polyurethane that can be dispersed and stabilized in water even if it is not present, any of them may be used in the present invention.

The method for applying the water-dispersible polyurethane to the fibrous base material is not particularly limited, but a method of impregnating and applying the water-dispersible polyurethane liquid to the fibrous base material, solidifying, and heating and drying can be uniformly applied. Therefore, it is preferable.

The concentration of the water-dispersible polyurethane liquid (polyurethane content relative to the water-dispersible polyurethane liquid) is preferably 10 to 50% by mass, more preferably 15 to 40% by mass, from the viewpoint of storage stability of the water-dispersible polyurethane liquid. It is.

Further, the water-dispersed polyurethane liquid used in the present invention may contain a water-soluble organic solvent in an amount of 40% by mass or less based on the polyurethane liquid in order to improve storage stability and film-forming property. From the standpoint of maintenance and the like, the content of the organic solvent is preferably 1% by mass or less.

Further, as the water-dispersed polyurethane liquid used in the present invention, those having heat-sensitive coagulation properties are preferable. By using a water-dispersed polyurethane liquid having heat-sensitive coagulation properties, polyurethane can be uniformly applied in the thickness direction of the fibrous base material.

In the present invention, heat-sensitive coagulation refers to the property that when a polyurethane liquid is heated, the fluidity of the polyurethane liquid decreases and solidifies when it reaches a certain temperature (thermal coagulation temperature). In the production of a sheet with polyurethane, a polyurethane liquid is applied to a fibrous base material, and then solidified by dry coagulation, wet heat coagulation, wet coagulation, or a combination thereof, and dried to give polyurethane to the fibrous base material. Give. As a method of coagulating water-dispersed polyurethane liquid that does not exhibit heat-sensitive coagulation, dry coagulation is practical in industrial production, but in this case, a migration phenomenon occurs in which polyurethane concentrates on the surface layer of the fibrous base material. The texture of the sheet with polyurethane tends to harden. In that case, migration can be prevented by adjusting the viscosity of the water-dispersed polyurethane liquid with a thickener. Also, in the case of a water-dispersed polyurethane liquid exhibiting heat-sensitive coagulation, migration can be prevented by adding a thickener and dry coagulating.

The heat-sensitive coagulation temperature of the water-dispersed polyurethane liquid is preferably 40 to 90 ° C. By setting the heat-sensitive coagulation temperature to 40 ° C. or higher, stability during storage of the polyurethane liquid is improved, and adhesion of polyurethane to the machine during operation can be suppressed. Moreover, the migration phenomenon of the polyurethane to the surface layer of a fibrous base material can be suppressed by making thermosensitive coagulation temperature into 90 degrees C or less.

In one embodiment of the present invention, a thermal coagulant may be added as appropriate in order to set the thermal coagulation temperature as described above. Examples of heat-sensitive coagulants include inorganic salts such as sodium sulfate, magnesium sulfate, calcium sulfate, and calcium chloride; radical reactions such as sodium persulfate, potassium persulfate, ammonium persulfate, azobisisobutyronitrile, and benzoyl peroxide are initiated. Agents and the like.

In a preferred embodiment of the present invention, the polyurethane liquid can be coagulated by dry coagulation, wet heat coagulation, wet coagulation, or a combination thereof by impregnating and applying a polyurethane liquid to a fibrous base material.

The wet heat coagulation temperature is preferably equal to or higher than the heat sensitive coagulation temperature of polyurethane, and is preferably 40 to 200 ° C. By setting the wet heat solidification temperature to 40 ° C. or higher, more preferably 80 ° C. or higher, the time to solidification of the polyurethane can be shortened to further suppress the migration phenomenon. On the other hand, by setting the wet heat coagulation temperature to 200 ° C. or lower, more preferably 160 ° C. or lower, it is possible to prevent thermal degradation of polyurethane and PVA.

The wet coagulation temperature is not less than the heat-sensitive coagulation temperature of polyurethane and is preferably 40 to 100 ° C. By setting the temperature of wet coagulation in hot water to 40 ° C. or higher, more preferably 80 ° C. or higher, the time to solidification of polyurethane can be shortened to further suppress the migration phenomenon.

The dry coagulation temperature and the drying temperature are preferably 80 to 140 ° C. By setting the dry solidification temperature and the drying temperature to 80 ° C. or higher, more preferably 90 ° C. or higher, the productivity is excellent. On the other hand, by setting the dry coagulation temperature and the drying temperature to 140 ° C. or lower, more preferably 130 ° C. or lower, it is possible to prevent thermal degradation of polyurethane and PVA.
In the present invention, heat treatment may be performed after the polyurethane is solidified. By performing the heat treatment, the interface between the polyurethane molecules decreases, and the polyurethane becomes stronger. In a more preferred embodiment, it is preferable to perform heat treatment after removing PVA from the sheet provided with water-dispersed polyurethane. The temperature of the heat treatment is preferably 80 to 170 ° C.

As the polyurethane used in the present invention, a polyurethane obtained by a reaction of a polymer diol, an organic diisocyanate and a chain extender is preferable.

The polymer diol is not particularly limited. For example, polycarbonate-based, polyester-based, polyether-based, silicone-based, and fluorine-based diols can be used, and a copolymer obtained by combining these may be used. From the viewpoint of hydrolysis resistance, polycarbonate-based and polyether-based diols are preferably used. From the viewpoints of light resistance and heat resistance, polycarbonate and polyester are preferably used. Furthermore, from the viewpoint of the balance between hydrolysis resistance, heat resistance and light resistance, polycarbonate-based and polyester-based diols are more preferable, and polycarbonate-based diols are particularly preferably used.

The polycarbonate diol can be produced by a transesterification reaction between an alkylene glycol and a carbonate ester, or a reaction between phosgene or chloroformate ester and an alkylene glycol.

The alkylene glycol is not particularly limited. For example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10 -Linear alkylene glycol such as decanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-methyl-1,8-octanediol, etc. Branched alkylene glycols, alicyclic diols such as 1,4-cyclohexanediol, aromatic diols such as bisphenol A, glycerin, trimethylolpropane, and pentaerythritol. Either a polycarbonate diol obtained from a single alkylene glycol or a copolymerized polycarbonate diol obtained from two or more types of alkylene glycols may be used.

Examples of the polyester-based diol include polyester diols obtained by condensing various low molecular weight polyols and polybasic acids.

The low molecular weight polyol is not particularly limited, and examples thereof include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, and 2,2-dimethyl. -1,3-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexane-1 , 4-diol, and cyclohexane-1,4-dimethanol can be used. Further, addition products obtained by adding various alkylene oxides to bisphenol A can also be used.

Further, the polybasic acid is not particularly limited, for example, succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, phthalic acid, isophthalic acid, One type or two or more types selected from terephthalic acid and hexahydroisophthalic acid may be mentioned.

The polyether diol is not particularly limited, and examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymer diols obtained by combining them.

The number average molecular weight of the polymer diol used in the present invention is preferably 500 to 4000. By setting the number average molecular weight to 500 or more, more preferably 1500 or more, it is possible to prevent the texture from becoming hard. Moreover, the intensity | strength as a polyurethane is maintainable by making a number average molecular weight into 4000 or less, More preferably, 3000 or less.

The organic diisocyanate is not particularly limited. These may be used, and these may be used in combination. Among these, aliphatic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate and isophorone diisocyanate are preferably used from the viewpoint of light resistance.

The chain extender is not particularly limited, and amine chain extenders such as ethylenediamine and methylenebisaniline, and diol chain extenders such as ethylene glycol can be used. Moreover, the polyamine obtained by making polyisocyanate and water react can also be used as a chain extender.

In the polyurethane, if desired, a crosslinking agent may be used in combination for the purpose of improving water resistance, abrasion resistance, hydrolysis resistance and the like. The cross-linking agent may be an external cross-linking agent added as a third component to the polyurethane, or may be an internal cross-linking agent that introduces a reaction point that becomes a cross-linked structure in advance in the polyurethane molecular structure. In the present invention, it is preferable to use an internal cross-linking agent from the viewpoint that the cross-linking points can be formed more uniformly in the polyurethane molecular structure and the reduction in flexibility can be reduced.

As the crosslinking agent, a compound having an isocyanate group, an oxazoline group, a carbodiimide group, an epoxy group, a melamine resin, a silanol group, or the like can be used. However, when the crosslinking proceeds excessively, the polyurethane tends to harden and the texture of the sheet-like material also tends to harden. Therefore, those having a silanol group are preferably used in terms of the balance between reactivity and flexibility.

Also, the polyurethane used in the present invention preferably has a hydrophilic group in the molecular structure. By having a hydrophilic group in the molecular structure, the dispersion / stability of the water-dispersed polyurethane can be improved.

Examples of the hydrophilic group include a cation system such as a quaternary amine salt, an anion system such as a sulfonate and carboxylate, a nonionic system such as polyethylene glycol, a combination of a cationic system and a nonionic system, and an anionic system and a nonionic system. Any hydrophilic group of the combination of systems can be employed. Of these, nonionic hydrophilic groups that are free from yellowing caused by light and harmful effects caused by a neutralizing agent are particularly preferably used.

In the case of an anionic hydrophilic group, a neutralizing agent is required. For example, the neutralizing agent is a tertiary amine such as ammonia, triethylamine, triethanolamine, triisopropanolamine, trimethylamine and dimethylethanolamine. In some cases, amines are generated and volatilized by heat during film formation and drying, and released outside the system. For this reason, in order to suppress the release of air and the deterioration of the working environment, it is essential to introduce a device for recovering volatile amines. In addition, if the amine does not volatilize by heating and remains in the final product sheet, it may be discharged to the environment when the product is incinerated. On the other hand, in the case of a nonionic hydrophilic group, it is not necessary to introduce an amine recovery device because a neutralizing agent is not used, and there is no fear of residual amine in the sheet-like material, so that it is preferably used. it can.

Further, when the anionic hydrophilic group neutralizing agent is an alkali metal such as sodium hydroxide, potassium hydroxide or calcium hydroxide, or a hydroxide of an alkaline earth metal, the polyurethane part is wetted with water. Although it shows alkalinity, in the case of a nonionic hydrophilic group, since a neutralizing agent is not used, there is no need to worry about deterioration due to hydrolysis of polyurethane.

The water-dispersed polyurethane used in the present invention is optionally made of various additives, for example, pigments such as carbon black, flame retardants such as phosphorus, halogen, silicone and inorganic, phenol, sulfur and phosphorus. Antioxidants such as benzotriazoles, benzophenones, salicylates, cyanoacrylates and oxalic acid anilides, light stabilizers such as hindered amines and benzoates, and hydrolysis resistance of polycarbodiimides Stabilizers, plasticizers, antistatic agents, surfactants, softeners, water repellents, coagulation modifiers, viscosity modifiers, dyes, preservatives, antibacterial agents, deodorants, cellulose particles, fillers such as microballoons , And inorganic particles such as silica and titanium oxide. In order to further increase the gap between the fiber and the polyurethane, an inorganic system such as sodium bicarbonate, an organic system such as 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], etc. A foaming agent may be contained.

The content ratio of polyurethane to the fibrous base material containing the ultrafine fiber of the present invention as a main constituent is preferably 1 to 80% by mass. By setting the ratio of the polyurethane to 1% by mass or more, more preferably 5% by mass or more, it is possible to obtain sheet strength and prevent the fibers from falling off. Moreover, by setting the blending ratio of polyurethane to 80% by mass or less, more preferably 70% by mass or less, it is possible to prevent the texture from becoming hard and to obtain good napped quality.

[Fifth step]
Next, the process of removing PVA from the fibrous base material having as main components ultrafine fibers provided with PVA and water-dispersed polyurethane, which is a fifth process, will be described.

In a preferred embodiment of the present invention, a flexible sheet-like material is obtained by removing PVA from the fibrous base material after application of polyurethane. The method for removing PVA is not particularly limited, but for example, it is preferable to dissolve and remove the sheet by immersing the sheet in hot water at 60 to 100 ° C. and squeezing with a mangle if necessary.

The method for producing a sheet-like product of the present invention may include a step of half-cutting in the thickness direction after applying water-dispersed polyurethane to at least a fibrous base material provided with PVA. In the step of applying PVA, a large amount of PVA adheres to the surface layer of the fibrous base material due to migration, and the amount of PVA attached to the inner layer is small. Then, by applying water-dispersed polyurethane and then half-cutting in the thickness direction, a small amount of water-dispersed polyurethane adheres to the side with a large amount of PVA, and a large amount of water-dispersed polyurethane to a side with a small amount of PVA. A sheet-like material having an attached structure is obtained. When the surface on which a large amount of PVA is adhered (the surface on which less water-dispersed polyurethane adheres) is used as the napped surface of the sheet-like material, there is a gap between the polyurethane and the ultrafine fibers constituting the napped by the addition of PVA. Is generated, the degree of freedom is given to the fibers constituting the nap, the surface texture becomes flexible, and a good appearance quality and soft touch can be obtained. On the other hand, when the surface on which the PVA is adhered to a small amount (the surface on which the water-dispersed polyurethane is largely adhered) is used as the raised surface of the sheet-like material, the raised hair is short because the fibers constituting the raised hair are strongly held by the polyurethane. However, a good appearance quality with a dense feeling is obtained, and the wear resistance is also good. Furthermore, production efficiency can be improved by including the process of half-cutting in the sheet thickness direction.

In the present invention, at least one surface of the sheet-like material may be raised to form napped on the surface. The method for forming napping is not particularly limited, and various methods that are usually performed in this field, such as buffing with sandpaper or the like, can be used. When the napped length is too short, it is difficult to obtain an elegant appearance, and when it is too long, pilling tends to occur. Therefore, the napped length is preferably 0.2 to 1 mm.

Further, in one embodiment of the present invention, silicone or the like may be applied to the sheet-like material as a lubricant before the raising treatment. By applying a lubricant, raising by surface grinding becomes possible easily, and the surface quality becomes very good, which is preferable. In addition, an antistatic agent may be applied before the raising treatment, which is a preferred embodiment because the application of the antistatic agent makes it difficult for grinding powder generated from the sheet-like material to be deposited on the sandpaper by grinding.

In one embodiment of the present invention, the sheet can be dyed. As a dyeing method, various methods commonly used in this field can be adopted. However, since the sheet-like material can be softened by giving a stagnation effect simultaneously with the dyeing of the sheet-like material, a liquid dyeing machine is used. The method used is preferred.

The dyeing temperature is preferably 80 to 150 ° C., although it depends on the type of fiber. By setting the dyeing temperature to 80 ° C. or higher, more preferably 110 ° C. or higher, it is possible to efficiently dye the fibers. On the other hand, the deterioration of the polyurethane can be prevented by setting the dyeing temperature to 150 ° C. or lower, more preferably 130 ° C. or lower.

The dye used in the present invention may be selected in accordance with the type of fiber constituting the fibrous base material, and is not particularly limited. For example, a disperse dye can be used for a polyester fiber, and a polyamide fiber. If so, an acid dye or a metal-containing dye can be used, and further a combination thereof can be used. When dyed with disperse dyes, reduction washing may be performed after dyeing.

In addition, it is also a preferable aspect to use a dyeing assistant during dyeing. By using a dyeing assistant, the uniformity and reproducibility of dyeing can be improved. Further, after the same bath as the dyeing or after dyeing, a finishing agent treatment using, for example, a softener such as silicone, an antistatic agent, a water repellent, a flame retardant, a light proofing agent, and an antibacterial agent can be performed.

The density of the sheet-like material of the present invention thus obtained is preferably 0.2 to 0.7 g / cm ³ . By setting the density to 0.2 g / cm ³ or more, more preferably 0.3 g / cm ³ or more, the surface appearance becomes dense and high-grade quality can be expressed. On the other hand, by setting the density to 0.7 g / cm ³ or less, more preferably 0.6 g / cm ³ or less, it is possible to prevent the texture of the sheet-like material from becoming hard.

Next, the production method of the sheet-like product of the present invention will be described in more detail by way of examples. However, the present invention is not limited only to these examples, and many modifications may be applied to the technical idea of the present invention. It is possible by those having ordinary knowledge in the field.

[Evaluation methods]
(1) Organic solvent concentration of PVA aqueous solution 1 g of PVA aqueous solution was put into a 24 mL heating tube and heated at 90 ° C. for 1 hour. From the heating tube, 0.1 mL of the generated gas was collected with a gas tight syringe, introduced into GC / MS, and analyzed for the concentration of methyl acetate, acetic acid, and methanol. The GC / MS detection limit is less than 0.1 ppm.

(2) Viscosity of PVA aqueous solution The viscosity at 20 ° C. of a 4% by mass PVA aqueous solution was measured by the rotational viscometer method described in 3.11.1 of JIS K6726 (1994) polyvinyl alcohol test method.

(3) Tensile strength of PVA A 10% by mass PVA aqueous dispersion was placed in a polyethylene tray having a longitudinal direction of 5 cm, a transverse direction of 10 cm and a depth of 1 cm, air-dried at 25 ° C. for 8 hours, and then dried with hot air at a temperature of 120 ° C. A PVA dry film having a thickness of 100 μm was obtained by heat treatment with a machine for 2 hours. About this PVA dry-type film | membrane, the tensile strength was measured with the tension tester according to A method (strip method) of JISL1096 (2010) 8.14.1.

(4) Average single fiber diameter The average single fiber diameter was obtained by taking a scanning electron microscope (SEM) photograph of the surface of the fibrous base material or sheet-like material at a magnification of 2000 times, selecting 100 fibers at random, and the single fiber diameter. Was calculated by calculating the average value.
When the fiber constituting the fibrous base material or the sheet-like material had an irregular cross section, the outer circumference circle diameter of the irregular cross section was calculated as the single fiber diameter. Also, when the circular cross section and the irregular cross section are mixed, or when the single fiber diameters are greatly different, etc., the number of samplings corresponding to each existing number ratio is selected and calculated to be a total of 100. did. However, when a reinforcing woven fabric or knitted fabric is inserted in the fibrous base material, the fibers of the reinforcing woven fabric or knitted fabric are excluded from the sampling target in the measurement of the average single fiber diameter.

(5) Bending softness of sheet-like material Based on A method (45 ° cantilever method) described in JIS L1096 (2010) 8.21.1, test pieces each having a size of 2 cm × 15 cm in the vertical direction and the horizontal direction were prepared. The test piece was placed on a horizontal platform having a 45 ° slope, and the position of the other end when the center point of one end of the test piece was in contact with the slope was read with a scale. The bending resistance is represented by the length (mm) that the test piece has moved. The average value of the moving lengths of the five test pieces was determined and used as the bending resistance.

(6) Surface appearance of sheet-like material The surface appearance of the sheet-like material is determined by visual and sensory evaluation as follows, with 10 adult males and 10 adult females each in good health, and a total of 20 evaluators. A stepped evaluation was performed, and the highest evaluation was defined as the surface appearance. As for the surface appearance, Grade 3 to Grade 5 were good.
Grade 5: There is uniform fiber napping, the fiber dispersion state is good, and the appearance is good.
Grade 4: Evaluation between grade 5 and grade 3.
Third grade: The dispersion state of the fibers is slightly poor, but there are fiber nappings and the appearance is reasonably good.
Second grade: An evaluation between the third grade and the first grade.
First grade: Overall, the dispersion state of the fibers is very poor, or the fibers are long and the appearance is poor.

(7) Abrasion resistance evaluation of sheet-like material Nylon 6 nylon fiber having a diameter of 0.4 mm cut into a length of 11 mm perpendicular to the longitudinal direction of the fiber was made into 100 bundles, and this bundle was made 110 mm in diameter. 97 in a 6-fold concentric circle (1 in the center, 6 in the 17 mm diameter circle, 13 in the 37 mm diameter circle, 19 in the 55 mm diameter circle, 26 in the 74 mm diameter circle, Using circular brushes (9700 nylon threads) arranged in 32 circles with a diameter of 90 mm, equally spaced in each circle, under the conditions of a load of 8 pounds (about 3629 g), a rotation speed of 65 rpm, and a rotation speed of 50 times The surface of a round sample (45 mm in diameter) was abraded and the change in mass of the sample before and after that was measured, and the weight loss (mg), which is the average value of the change in mass of 5 samples, was defined as wear resistance.

[Example 1]
(Preparation of PVA aqueous solution)
PVA having a saponification degree of 99% and a polymerization degree of 1400 (NM-14 manufactured by Nippon Synthetic Chemical Co., Ltd.) was added to water at 25 ° C., heated to 90 ° C., maintained at 90 ° C. with stirring for 2 hours, A PVA aqueous solution was obtained by preparing an aqueous solution having a solid content of 10% by mass. The methyl acetate, acetic acid, and methanol concentrations contained in the PVA aqueous solution were 10.2 ppm, 0.8 ppm, and 5.2 ppm, respectively.

(Nonwoven fabric for fibrous base materials)
Polyethylene terephthalate copolymerized with 8 mol% of sodium 5-sulfoisophthalate was used as the sea component, and polyethylene terephthalate was used as the island component, with a composite ratio of 45 mass% sea component and 55 mass% island component. / 1 filament, sea island type composite fiber having an average single fiber diameter of 17 μm was obtained. The obtained sea-island type composite fiber was cut into a fiber length of 51 mm to form a staple, a fiber web was formed through a card and a cross wrapper, and a nonwoven fabric was formed by needle punching. The nonwoven fabric thus obtained was immersed in hot water at a temperature of 98 ° C. for 2 minutes to shrink and dried at a temperature of 100 ° C. for 5 minutes to obtain a nonwoven fabric for a fibrous base material.

(Granting PVA)
The above PVA aqueous solution is impregnated into the above-mentioned nonwoven fabric for a fibrous base material, heat-dried at a temperature of 140 ° C. for 10 minutes, and the amount of PVA applied to the fiber mass of the nonwoven fabric for a fibrous base material is 30 mass%. A sheet was obtained.

(Fiber miniaturization (sea removal))
The PVA-applied sheet was immersed in a 10 g / liter sodium hydroxide aqueous solution heated to a temperature of 95 ° C. and treated for 30 minutes to obtain a sea-removed sheet from which sea components of sea-island type composite fibers were removed. The average single fiber diameter on the surface of the sea removal sheet was 3 μm.

(Preparation of polyurethane liquid)
To 100 parts by mass of a polycarbonate-based self-emulsifying polyurethane liquid in which polyhexamethylene carbonate is applied to the polyol and dicyclohexylmethane diisocyanate is applied to the isocyanate, 2 parts by mass of ammonium persulfate (APS) is added as a heat-sensitive coagulant, The whole was prepared to a solid content of 20% by mass with water to obtain a water-dispersed polyurethane liquid. The thermal coagulation temperature was 72 ° C.

(Applying polyurethane)
The seawater-free sheet provided with the above PVA is impregnated with the above-mentioned polycarbonate-based polyurethane liquid, treated in a moist and hot atmosphere at a temperature of 100 ° C. for 5 minutes, then dried with hot air at a drying temperature of 120 ° C. for 5 minutes, and further 140 By performing a dry heat treatment at a temperature of 2 ° C. for 2 minutes, a sheet to which polyurethane was applied was obtained so that the amount of polyurethane attached to the fiber mass of the nonwoven fabric was 30% by mass.

(Removal of PVA)
The sheet provided with the polyurethane was immersed in water heated to 95 ° C. and treated for 10 minutes to obtain a sheet from which the applied PVA was removed.

(Half-cut, brushed, dyed, reduced cleaning)
The PVA-removed sheet is cut in half in the thickness direction, and the surface opposite to the half-cut surface is brushed by grinding using a 240 mesh endless sandpaper, and then dyed with a disperse dye using a circular dyeing machine and reduced. Washing was performed to obtain a sheet. The surface appearance of the obtained sheet-like material was good, had a soft texture, and had good wear resistance.

[Example 2]
(Preparation of PVA aqueous solution)
In the same manner as in Example 1, a PVA aqueous solution was obtained.
(Nonwoven fabric for fibrous base materials)
In the same manner as in Example 1, a nonwoven fabric for fibrous base material was obtained.
(Granting PVA)
Using the same PVA aqueous solution as in Example 1 and adjusting the squeezing after impregnation to change the amount of PVA attached, the amount of PVA attached to the fiber mass of the nonwoven fabric for fibrous base material was the same as in Example 1. Obtained a 20% by mass PVA-applied sheet.
(Fiber miniaturization (sea removal))
In the same manner as in Example 1, a sea removal sheet was obtained.
(Preparation of polyurethane liquid)
A water-dispersed polyurethane liquid was obtained in the same manner as in Example 1.
(Applying polyurethane)
In the same manner as in Example 1, a polyurethane-applied sheet was obtained.
(Removal of PVA)
In the same manner as in Example 1, a PVA removal sheet was obtained.
(Half-cut, brushed, dyed, reduced cleaning)
A sheet-like material was obtained in the same manner as in Example 1. The surface appearance of the obtained sheet-like material was good, had a soft texture, and had good wear resistance.

[Example 3]
(Preparation of PVA aqueous solution)
In the same manner as in Example 1, a PVA aqueous solution was obtained.
(Nonwoven fabric for fibrous base materials)
As the sea component, polyethylene terephthalate copolymerized with 8 mol% of sodium 5-sulfoisophthalate is used, and as the island component, polyethylene terephthalate is used. The sea component is 20% by mass and the island component is 80% by mass. / 1 filament, sea island type composite fiber having an average single fiber diameter of 30 μm was obtained. The obtained sea-island type composite fiber was cut into a fiber length of 51 mm to form a staple, a fiber web was formed through a card and a cross wrapper, and a nonwoven fabric was formed by needle punching. The nonwoven fabric thus obtained was immersed in hot water at a temperature of 98 ° C. for 2 minutes to shrink and dried at a temperature of 100 ° C. for 5 minutes to obtain a nonwoven fabric for a fibrous base material.

(Granting PVA)
Using the same PVA aqueous solution as in Example 1, a PVA-attached sheet having an adhesion amount of PVA of 30% by mass with respect to the fiber mass of the nonwoven fabric for fibrous base material was obtained.
(Fiber miniaturization (sea removal))
The nonwoven fabric for fibrous base material was treated in the same manner as in Example 1 to obtain a sea removal sheet from which sea components of the sea-island type composite fibers were removed. The average single fiber diameter on the surface of the sea removal sheet was 4.4 μm.
(Preparation of polyurethane liquid)
The same water dispersion type polyurethane liquid as in Example 1 was used.
(Applying polyurethane)
In the same manner as in Example 1, a polyurethane-applied sheet was obtained.
(Removal of PVA)
In the same manner as in Example 1, a PVA removal sheet was obtained.
(Half-cut, brushed, dyed, reduced cleaning)
A sheet-like material was obtained in the same manner as in Example 1. The surface appearance of the obtained sheet-like material was good, had a soft texture, and had good wear resistance.

[Example 4]
(Preparation of PVA aqueous solution)
PVA having a saponification degree of 99% and a polymerization degree of 1100 (NM-11 manufactured by Nippon Synthetic Chemical Co., Ltd.) was added to water at 25 ° C., heated to 90 ° C., maintained at 90 ° C. with stirring for 2 hours, A PVA aqueous solution was obtained by preparing an aqueous solution having a solid content of 10% by mass. The concentrations of methyl acetate, acetic acid, and methanol contained in the PVA aqueous solution were 7.2 ppm, 0.4 ppm, and 2.4 ppm, respectively.
(Nonwoven fabric for fibrous base materials)
The same nonwoven fabric for a fibrous base material as in Example 1 was used.
(Granting PVA)
The above PVA aqueous solution is impregnated into the above-mentioned nonwoven fabric for a fibrous base material, heat-dried at a temperature of 140 ° C. for 10 minutes, and the amount of PVA applied to the fiber mass of the nonwoven fabric for a fibrous base material is 30 mass%. A sheet was obtained.
(Fiber miniaturization (sea removal))
In the same manner as in Example 1, a sea removal sheet was obtained from the nonwoven fabric for fibrous base material.
(Preparation of polyurethane liquid)
The same water dispersion type polyurethane liquid as in Example 1 was used.
(Applying polyurethane)
In the same manner as in Example 1, a polyurethane-applied sheet was obtained.
(Removal of PVA)
In the same manner as in Example 1, a PVA removal sheet was obtained.
(Half-cut, brushed, dyed, reduced cleaning)
A sheet-like material was obtained in the same manner as in Example 1. The surface appearance of the obtained sheet-like material was good, had a soft texture, and had good wear resistance.

[Example 5]
(Preparation of PVA aqueous solution)
PVA having a saponification degree of 99% and a polymerization degree of 2600 (NH-26 manufactured by Nippon Synthetic Chemical Co., Ltd.) was added to water at 25 ° C., heated to 90 ° C., maintained at 90 ° C. with stirring for 2 hours, A PVA aqueous solution was obtained by preparing an aqueous solution having a solid content of 10% by mass. The concentrations of methyl acetate, acetic acid and methanol contained in the PVA aqueous solution were 32.2 ppm, 8.3 ppm and 20.1 ppm, respectively.
(Nonwoven fabric for fibrous base materials)
The same nonwoven fabric for a fibrous base material as in Example 1 was used.
(Granting PVA)
The nonwoven fabric for a fibrous base material is impregnated with the above PVA aqueous solution, dried by heating at a temperature of 140 ° C. for 10 minutes, and the amount of PVA applied to the fiber mass of the nonwoven fabric for a fibrous base material is 10 mass%. A sheet was obtained.
(Fiber miniaturization (sea removal))
In the same manner as in Example 1, a sea removal sheet was obtained from the nonwoven fabric for fibrous base material.
(Preparation of polyurethane liquid)
The same water dispersion type polyurethane liquid as in Example 1 was used.
(Applying polyurethane)
In the same manner as in Example 1, a polyurethane-applied sheet was obtained.
(Removal of PVA)
In the same manner as in Example 1, a PVA removal sheet was obtained.
(Half-cut, brushed, dyed, reduced cleaning)
A sheet-like material was obtained in the same manner as in Example 1. The surface appearance of the obtained sheet-like material was good, had a soft texture, and had good wear resistance.

[Example 6]
(Preparation of PVA aqueous solution)
In the same manner as in Example 1, a PVA aqueous solution was obtained.
(Nonwoven fabric for fibrous base materials)
As the sea component, polyethylene terephthalate copolymerized with 8 mol% of sodium 5-sulfoisophthalate is used, and as the island component, polyethylene terephthalate is used. The sea component is 20% by mass and the island component is 80% by mass. / 1 filament, sea island type composite fiber having an average single fiber diameter of 30 μm was obtained. The obtained sea-island type composite fiber was cut into a fiber length of 51 mm to form a staple, and a fiber web was formed through a card and a cross wrap. 84 dtex-72 filaments of polyethylene terephthalate (PET) on both sides of the web and a twist of 2000 T / m A plain woven fabric using strong twisted yarn was laminated and made into a nonwoven fabric by needle punching. The nonwoven fabric thus obtained was immersed in hot water at a temperature of 98 ° C. for 2 minutes to shrink and dried at a temperature of 100 ° C. for 5 minutes to obtain a nonwoven fabric for a fibrous base material.

(Granting PVA)
The above PVA aqueous solution is impregnated into the above-mentioned nonwoven fabric for a fibrous base material, dried by heating at a temperature of 140 ° C. for 10 minutes, and the amount of PVA applied to the fiber mass of the nonwoven fabric for a fibrous base material is 15 mass%. A sheet was obtained.
(Fiber miniaturization (sea removal))
The nonwoven fabric for fibrous base material was treated in the same manner as in Example 1 to obtain a sea removal sheet from which sea components of the sea-island type composite fibers were removed. The average single fiber diameter on the surface of the sea removal sheet was 4.4 μm.
(Preparation of polyurethane liquid)
The same water dispersion type polyurethane liquid as in Example 1 was used.
(Applying polyurethane)
In the same manner as in Example 1, a polyurethane-applied sheet was obtained.
(Removal of PVA)
In the same manner as in Example 1, a PVA removal sheet was obtained.
(Half-cut, brushed, dyed, reduced cleaning)
A sheet-like material was obtained in the same manner as in Example 1. The surface appearance of the obtained sheet-like material was good, had a soft texture, and had good wear resistance.

[Example 7]
(Preparation of PVA aqueous solution)
In the same manner as in Example 1, a PVA aqueous solution was obtained.
(Nonwoven fabric for fibrous base materials)
In the same manner as in Example 1, a nonwoven fabric for fibrous base material was obtained.
(Granting PVA)
In the same manner as in Example 1, a PVA-applied sheet having a PVA adhesion amount of 30 mass% with respect to the fiber mass of the nonwoven fabric for fibrous base material was obtained.
(Fiber miniaturization (sea removal))
In the same manner as in Example 1, a sea removal sheet was obtained.
(Preparation of polyurethane liquid)
5 parts by mass of a thickener (SN thickener 627N manufactured by San Nopco Co., Ltd.) with respect to 100 parts by mass of the solid content of a polycarbonate-based self-emulsifying polyurethane liquid in which polyhexamethylene carbonate is applied to polyol and dicyclohexylmethane diisocyanate is applied to isocyanate. And the whole was adjusted to 20 mass% polyurethane solids with water to obtain a water-dispersed polyurethane liquid.
(Applying polyurethane)
The seawater-sealed sheet provided with the above PVA is impregnated with the above-mentioned polyurethane liquid and dried with hot air at a drying temperature of 100 ° C. for 30 minutes, so that the amount of polyurethane attached to the nonwoven fabric fiber mass becomes 30% by mass. A sheet with polyurethane added thereto was obtained.
(Removal of PVA)
In the same manner as in Example 1, a PVA removal sheet was obtained.
(Half-cut, brushed, dyed, reduced cleaning)
A sheet-like material was obtained in the same manner as in Example 1. The surface appearance of the obtained sheet-like material was good, had a soft texture, and had good wear resistance.

[Example 8]
(Preparation of PVA aqueous solution)
In the same manner as in Example 5, a PVA aqueous solution was obtained.
(Nonwoven fabric for fibrous base materials)
The same nonwoven fabric for a fibrous base material as in Example 1 was used.
(Granting PVA)
The nonwoven fabric for a fibrous base material is impregnated with the above PVA aqueous solution, dried by heating at a temperature of 140 ° C. for 10 minutes, and the amount of PVA applied to the fiber mass of the nonwoven fabric for a fibrous base material is 10 mass%. A sheet was obtained.
(Fiber miniaturization (sea removal))
In the same manner as in Example 1, a sea removal sheet was obtained from the nonwoven fabric for fibrous base material.
(Preparation of polyurethane liquid)
To 100 parts by mass of a polycarbonate-based self-emulsifying polyurethane liquid in which polyhexamethylene carbonate is applied to the polyol and dicyclohexylmethane diisocyanate is applied to the isocyanate, 2 parts by mass of ammonium persulfate (APS) is added as a heat-sensitive coagulant, The whole was prepared to a solid content of 20% by mass with water to obtain a water-dispersed polyurethane liquid. The thermal coagulation temperature was 72 ° C.
(Applying polyurethane)
The seawater-sealed sheet provided with the above PVA is impregnated with the above-mentioned polyurethane liquid, solidified in warm water at 80 ° C., and dried with hot air at 100 ° C. for 15 minutes, whereby the amount of polyurethane attached to the fiber mass of the nonwoven fabric is 30 The sheet | seat which provided the polyurethane so that it might become mass% was obtained.
(Removal of PVA)
In the same manner as in Example 1, a PVA removal sheet was obtained.
(Half-cut, brushed, dyed, reduced cleaning)
A sheet-like material was obtained in the same manner as in Example 1. The surface appearance of the obtained sheet-like material was good, had a soft texture, and had good wear resistance.

[Comparative Example 1]
(Preparation of PVA aqueous solution)
In the same manner as in Example 1, a PVA aqueous solution was obtained.
(Nonwoven fabric for fibrous base materials)
The same nonwoven fabric for a fibrous base material as in Example 1 was used.
(Fiber miniaturization (sea removal))
The seawater-free nonwoven fabric for fiber base material obtained above is immersed in a 10 g / liter sodium hydroxide aqueous solution heated to a temperature of 95 ° C. and treated for 10 minutes to remove sea components from the sea-island composite fibers. A sheet was obtained. The average single fiber diameter on the surface of the sea removal sheet was 3 μm.
(Granting PVA)
The seawater-free sheet was impregnated with the PVA aqueous solution obtained in Example 1, and heat-dried at a temperature of 140 ° C. for 10 minutes to obtain a PVA-coated sheet having a PVA adhesion amount of 30% by mass on the seawater-free sheet.
(Preparation of polyurethane liquid)
The same water dispersion type polyurethane liquid as in Example 1 was used.
(Applying polyurethane)
The seawater-free sheet provided with the above PVA is impregnated with the above-mentioned polycarbonate-based polyurethane liquid, treated in a moist and hot atmosphere at a temperature of 100 ° C. for 5 minutes, and then dried with hot air at a drying temperature of 120 ° C. for 5 minutes, and further 140 By performing a dry heat treatment at a temperature of 2 ° C. for 2 minutes, a sheet to which polyurethane was applied so that the amount of polyurethane attached to the ultrafine fiber mass was 30% by mass was obtained.
(Removal of PVA)
In the same manner as in Example 1, a PVA removal sheet was obtained.
(Half-cut, brushed, dyed, reduced cleaning)
A sheet-like material was obtained in the same manner as in Example 1. The surface appearance of the obtained sheet-like material was good and had a soft texture, but the wear loss was much.

[Comparative Example 2]
(Preparation of PVA aqueous solution)
PVA having a saponification degree of 87% and a polymerization degree of 500 (GL-05 manufactured by Nippon Synthetic Chemical Co., Ltd.) was added to water at 25 ° C., heated to 90 ° C., maintained at 90 ° C. with stirring for 2 hours, A PVA aqueous solution was obtained by preparing an aqueous solution having a solid content of 10% by mass. The concentrations of methyl acetate, acetic acid and methanol contained in the PVA aqueous solution were 70.1 ppm, 40.1 ppm and 100.3 ppm, respectively.
(Nonwoven fabric for fibrous base materials)
The same nonwoven fabric for a fibrous base material as in Example 1 was used.
(Granting PVA)
The non-woven fabric for fibrous base material was impregnated with the above PVA aqueous solution, and the amount of PVA adhered was changed by adjusting the squeezing after the impregnation to change the non-woven fabric for fibrous base material in the same manner as in Example 1. A PVA-applied sheet having an adhesion amount of PVA with respect to mass of 10% by mass was obtained.
(Fiber miniaturization (sea removal))
In the same manner as in Example 1, a sea removal sheet was obtained from the nonwoven fabric for fibrous base material.
(Preparation of polyurethane liquid)
The same water dispersion type polyurethane liquid as in Example 1 was used.
(Applying polyurethane)
In the same manner as in Example 1, a polyurethane-applied sheet was obtained.
(Removal of PVA)
In the same manner as in Example 1, a PVA removal sheet was obtained.
(Half-cut, brushed, dyed, reduced cleaning)
A sheet-like material was obtained in the same manner as in Example 1. The obtained sheet-like material does not have a uniform applied state due to partial dissolution of PVA in an alkaline aqueous solution or a water-dispersed polyurethane liquid, and the surface appearance is poor in the state of fiber dispersion and inferior nap density. And the texture was hard.

[Comparative Example 3]
(Preparation of PVA aqueous solution)
PVA having a saponification degree of 99% and a polymerization degree of 500 (NL-05 manufactured by Nippon Synthetic Chemical Co., Ltd.) was added to water at 25 ° C., heated to 90 ° C., maintained at 90 ° C. with stirring for 2 hours, A PVA aqueous solution was obtained by preparing an aqueous solution having a solid content of 10% by mass. The concentrations of methyl acetate, acetic acid, and methanol contained in the PVA aqueous solution were 6.1 ppm, 0.4 ppm, and 1.1 ppm, respectively.
(Nonwoven fabric for fibrous base materials)
The same nonwoven fabric for a fibrous base material as in Example 1 was used.
(Granting PVA)
The non-woven fabric for fibrous base material was impregnated with the above PVA aqueous solution, and the amount of PVA adhered was changed by adjusting the squeezing after the impregnation to change the fibers of the non-woven fabric for fibrous base material. A PVA-applied sheet having an adhesion amount of PVA with respect to mass of 10% by mass was obtained.
(Fiber miniaturization (sea removal))
In the same manner as in Example 1, a sea removal sheet was obtained from the nonwoven fabric for fibrous base material.
(Preparation of polyurethane liquid)
The same water dispersion type polyurethane liquid as in Example 1 was used.
(Applying polyurethane)
In the same manner as in Example 1, a polyurethane-applied sheet was obtained.
(Removal of PVA)
In the same manner as in Example 1, a PVA removal sheet was obtained.
(Half-cut, brushed, dyed, reduced cleaning)
A sheet-like material was obtained in the same manner as in Example 1. The obtained sheet-like material does not have a uniform applied state due to partial dissolution of PVA in an alkaline aqueous solution or water-dispersed polyurethane liquid, and the surface appearance is poor in fiber dispersion state and inferior feeling of raised nail And the texture was hard.

[Comparative Example 4]
(Preparation of PVA aqueous solution)
In the same manner as in Example 1, a PVA aqueous solution was obtained.
(Nonwoven fabric for fibrous base materials)
The same nonwoven fabric for a fibrous base material as in Example 1 was used.
(Granting PVA)
Using the same PVA aqueous solution as in Example 1 and adjusting the squeezing after impregnation to change the amount of PVA attached, the amount of PVA attached to the fiber mass of the nonwoven fabric for fibrous base material was the same as in Example 1. Of 55% by mass was obtained.
(Fiber miniaturization (sea removal))
In the same manner as in Example 1, a sea removal sheet was obtained from the nonwoven fabric for fibrous base material.
(Preparation of polyurethane liquid)
The same water dispersion type polyurethane liquid as in Example 1 was used.
(Applying polyurethane)
In the same manner as in Example 1, a polyurethane-applied sheet was obtained.
(Removal of PVA)
In the same manner as in Example 1, a PVA removal sheet was obtained.
(Half-cut, brushed, dyed, reduced cleaning)
A sheet-like material was obtained in the same manner as in Example 1. The obtained sheet-like material was soft in texture, but because of too much PVA, the fiber was not sufficiently gripped by polyurethane, the surface appearance was too long and the wear was poor, and the wear resistance was poor Met.

[Comparative Example 5]
A sheet-like material was obtained in the same manner as in Example 1 except that the aqueous PVA solution was not prepared and the application and removal of PVA were not performed. The texture of the obtained sheet was hardened. Further, the surface appearance was poor with no raised hairs.
Tables 1 and 2 show the test conditions of each Example and Comparative Example and the evaluation results of the sheet-like material.

The sheet-like materials obtained in Examples 1 to 8 all had a good surface appearance, a soft texture, and good wear resistance. On the other hand, the abrasion resistance of the sheet-like materials obtained in Comparative Examples 1 and 4 was poor, and the sheet-like materials obtained in Comparative Examples 2 to 5 were all poor in surface appearance. Moreover, the texture of the sheet-like material obtained in Comparative Examples 2, 3, and 5 was hard.

The sheet-like material obtained by the present invention includes furniture, chairs and wall materials, interior materials having a very elegant appearance as a skin material such as seats, ceilings and interiors in vehicle interiors such as automobiles, trains and aircraft, shirts, Jackets, casual shoes, sports shoes, uppers and trims for shoes such as men's shoes and women's shoes, bags, belts, wallets, etc., clothing materials used for some of them, wiping cloth, polishing cloth, CD curtains, etc. It can be suitably used as an industrial material.

Claims (6)

1. A method for producing a sheet-like material, wherein the following steps 1 to 5 are sequentially performed.
   1. A step of dissolving polyvinyl alcohol having a saponification degree of 98% or more and a polymerization degree of 800 to 3500 in water to obtain a polyvinyl alcohol aqueous solution having a concentration of methyl acetate, acetic acid or methanol of 50 ppm or less,
   2. By applying the aqueous polyvinyl alcohol solution to a fibrous base material containing an ultrafine fiber-expressing fiber as a main constituent, the polyvinyl alcohol is added in an amount of 0.1 to 50% by mass with respect to the fiber mass contained in the fibrous base material. The step of applying,
   3. A step of expressing an ultrafine fiber having an average single fiber diameter of 0.3 to 7 μm from a fibrous base material having an ultrafine fiber expression type fiber as a main constituent component;
   4). A step of imparting water-dispersible polyurethane to a fibrous base material comprising, as a main constituent, ultrafine fibers to which the polyvinyl alcohol has been imparted,
   5. A step of removing polyvinyl alcohol from a fibrous base material comprising, as a main constituent, ultrafine fibers provided with the water-dispersed polyurethane.
2. The method for producing a sheet-like product according to claim 1, wherein the concentration of methyl acetate, acetic acid, and methanol in the polyvinyl alcohol aqueous solution is 0.1 to 50 ppm, respectively.
3. The method for producing a sheet-like product according to claim 1 or 2, wherein the step of developing ultrafine fibers is a step of treating with an alkaline aqueous solution.
4. The method for producing a sheet-like material according to any one of claims 1 to 3, comprising a step of applying the polyvinyl alcohol and heating at 80 to 170 ° C.
   
   
   
   
5. The sheet-like material according to any one of claims 1 to 4, wherein a fibrous base material comprising the ultrafine fiber-expressing fiber as a main constituent is intertwined with a woven fabric and / or a knitted fabric. Manufacturing method.
6. A sheet material obtained by the method for producing a sheet material according to any one of claims 1 to 5, wherein the density of the sheet material is 0.2 to 0.7 g / cm ³ .