JP7322477B2 - Sheet-shaped article and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sheet-like material having a high density, cordovan-like, dense and luxurious surface appearance, and a hard texture.

Conventionally, natural leather-like sheet-like materials are generally manufactured by imparting polymeric elastic material to a non-woven fabric in which fibers are three-dimensionally entangled in order to obtain flexibility and mechanical properties similar to those of natural leather. ing.

On the other hand, "cordovan", which has a unique hard texture and high hardness among natural leathers, is a leather harvested from the buttocks of horses with high rarity value. Excellent durability while having a good surface appearance.

As a means for obtaining a high-density sheet-like material, for example, a high-density sheet-like material has been proposed by applying an elastic polymer in two stages to a nonwoven fabric in which long fibers are three-dimensionally entangled (Patent References 1-3).

JP 2008-207323 A JP 2008-207325 A JP 2015-63782 A

As in the methods disclosed in Patent Documents 1 to 3, it is possible to some extent to increase the density of the sheet-like material by increasing the amount of elastic polymer applied to the sheet-like material. However, in these proposals, since the proportion of the elastic polymer in the sheet-like material is high, the texture is supple, and a cordovan-like hard texture cannot be obtained. In addition, since these proposals use a nonwoven fabric in which long fibers are three-dimensionally entangled, the number of fibers to be entangled in the thickness direction of the sheet-like material is reduced compared to a nonwoven fabric in which short fibers are three-dimensionally entangled. There is a problem that it is difficult to obtain a fine surface appearance.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sheet-shaped article comprising a nonwoven fabric comprising a fiber entangled body and a polymeric elastic body, which has a high density, a cordovan-like dense and luxurious surface appearance, and a hard material feel. It is about providing things.

As a result of intensive studies, the present inventors thermally shrunk a nonwoven fabric made of a fiber entangled body, further subjected to a high entanglement treatment, and then imparting a polymeric elastic body, thereby suppressing the adhesion amount of the polymeric elastic body. A sheet-like material having high density and a cordovan-like dense and luxurious surface appearance and a hard texture was obtained.

That is, the present invention aims to solve the above-mentioned problems, and the sheet-like material of the present invention is a sheet-like material composed of a nonwoven fabric made of a fiber entangled body and a polymeric elastic material, wherein the polymeric elastic material The weight ratio of the sheet is 0.01% by mass or more and 10% by mass or less, the apparent density of the sheet is 0.843 g/cm ³ or more and 1.3 g/cm ³ or less, and voids in the cross section of the sheet. The sheet-like material is characterized by having a rate of 0.1% or more and 16% or less.

According to a preferred aspect of the sheet-like article of the present invention, the average fiber length of the fibers constituting the nonwoven fabric is 15 mm or more and 90 mm or less.

According to a preferred embodiment of the sheet-like material of the present invention, in a cross-sectional SEM image of the sheet-like material in the thickness direction, the image area of the elastic polymer is 0.5 mm ² with respect to the image area corresponding to 0.5 mm 2 of the sheet-like material. It is equivalent to 00001 mm ² or more and equal to or less than 0.05 mm ² .

According to a preferred aspect of the sheet-shaped article of the present invention, the bending resistance is 50 mm or more and 180 mm or less.

According to a preferred embodiment of the sheet-shaped article of the present invention, the coefficient of variation (CV) of the void ratio of the cross-section of the sheet-shaped article is 30% or less.

According to a preferred aspect of the sheet-like article of the present invention, the fibers constituting the nonwoven fabric are made of at least one selected from polyethylene terephthalate, polyamide 6 and copolymers thereof.

The method for producing a sheet-like material of the present invention is a method for producing a sheet- like material comprising (a) a nonwoven fabric (fiber entangled body) forming step and (b) a nonwoven fabric densifying step, wherein the (a) nonwoven fabric The (fiber entangled body) forming step is a step of needle-punching a fiber web made of raw cotton having a boiling water shrinkage of 20% or more and 40% or less to form a nonwoven fabric, and the (b) nonwoven fabric densification step. is a step of water jet punching the nonwoven fabric at a pressure of 1 MPa or more and 60 MPa or less.

According to the present invention, the cross-sectional porosity of the sheet-like material is lower than that of the conventional sheet-like material, and the proportion of the polymer elastic body is low, so that the surface appearance and the cordovan-like dense and high-class appearance can be obtained. It is possible to obtain a sheet-like material having a hard texture.

The sheet-like material of the present invention is a sheet-like material composed of a nonwoven fabric made of a fiber entangled body and a polymeric elastic material, wherein the proportion of the polymeric elastic material is 10% by mass or less, and the apparent density of the sheet-like material is is 0.843 g/cm ³ or more and 1.3 g/cm ³ or less, and the cross-sectional porosity of the sheet is 0.1% or more and 16% or less. The constituent elements will be described in detail below, but the present invention is not limited to the scope described below as long as it does not exceed the gist of the present invention.

[Nonwoven fabric]
The nonwoven fabric constituting the sheet-shaped article of the present invention is made of a fiber entangled body. As types of fibers that constitute the fiber entanglement, for example, natural fibers, regenerated fibers, semi-synthetic fibers, synthetic fibers, and the like can be used. Among them, synthetic fibers are preferred from the viewpoint of durability, particularly mechanical strength, heat resistance and light resistance.

When synthetic fibers are used for the fiber entanglement, polyester, polyamide, polypropylene, polyethylene, etc. can be used depending on the application, but polyester and polyamide are preferred from the viewpoint of mechanical strength, heat resistance, etc. preferable.

The polyester that can be used in the present invention is not particularly limited as long as it is a polymer synthesized from a dicarboxylic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof and can be used as a fiber. not something. Specifically, for example, polyethylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, polyethylene-1,2-bis(2- chlorophenoxy)ethane-4,4'-dicarboxylate and the like. In the present invention, a polyester copolymer containing an ethylene terephthalate unit, which has high shrinkability, is preferably used.

As the copolymerization component, isophthalic acid and bisphenol A are preferably used from the viewpoint of the spinnability and the ability to develop high shrinkage properties. Also, the content of the copolymer component is preferably 2 mol % or more in order to sufficiently impart high shrinkage properties. However, if the content of the copolymer component exceeds 20 mol %, yarn breakage frequently occurs during spinning, so the content of the copolymer component is preferably 20 mol % or less.

Examples of polyamide (PA) that can be used in the present invention include polymers having an amide bond such as polyamide 6, polyamide 66, polyamide 610 and polyamide 12. Polyamide 6, which is excellent in dyeability, is preferably used in the present invention.

When synthetic fibers are used for the fiber entanglement, the polymer forming the fibers may include inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, ultraviolet absorbers, and conductive agents, depending on various purposes. , a heat storage agent, an antibacterial agent, and the like can be added.

As for the cross-sectional shape of the fiber, it is preferable to have a circular cross-section from the viewpoint of processing operability. It is also possible to adopt a cross-sectional shape with an irregular cross-section such as.

The fibers constituting the fiber entanglement are preferably ultrafine fibers having an average single fiber diameter of 0.01 μm or more and 10 μm or less. The average single fiber diameter is preferably 0.1 μm or more and 8 μm or less, more preferably 0.5 μm or more and 6 μm or less. If the thickness is less than 0.01 μm, the strength of the sheet material is lowered, which is not preferable. On the other hand, if the thickness exceeds 10 μm, the fineness of the surface is impaired, which is not preferable.

In the present invention, the average single fiber diameter is obtained by taking a scanning electron microscope (SEM) photograph of the cross section of a sheet-like material, randomly selecting 10 circular or nearly circular elliptical fibers, and measuring the single fiber diameter. shall be calculated by calculating the average value of 10 lines. However, when ultrafine fibers with irregular cross-sections are used, the cross-sectional area of the single fiber is first measured, and the diameter of the circle corresponding to the cross-sectional area is calculated by the following formula. The diameter thus obtained is taken as the single fiber diameter of the single fiber.
・Single fiber diameter (μm)=(4×(cross-sectional area of single fiber)/π) ^1/2 .

As the form of the nonwoven fabric constituting the sheet of the present invention, both a long fiber nonwoven fabric and a short fiber nonwoven fabric are used. The short-fiber nonwoven fabric is preferable because it is easy to obtain the short-fiber nonwoven fabric, and the average fiber length of the fibers constituting the short-fiber nonwoven fabric is preferably 15 mm or more and 90 mm or less. A fiber length of less than 90 mm provides good quality and texture, and a fiber length of more than 15 mm provides a sheet-like material with excellent abrasion resistance. The fiber length is more preferably 25 mm or more and 80 mm or less, and still more preferably 30 mm or more and 70 mm or less.

The basis weight of the nonwoven fabric forming the sheet-like article is preferably in the range of 100 g/m ² to 2000 g/m ² , more preferably in the range of 300 g/m ² to 1800 g/m ² . If the basis weight of the non-woven fabric is less than 100 g/m ² , the sheet-like material becomes paper-like and has poor texture. On the other hand, if the basis weight of the non-woven fabric exceeds 2000 g/m ² , the sheet-like material becomes extremely thick, which is not practically suitable for miscellaneous goods and clothing.

[Polymer elastic body]
Since the elastic polymer that constitutes the sheet-like material of the present invention is a binder that holds the fibers that constitute the sheet-like material, considering the hard texture of the sheet-like material of the present invention, the elastic polymer used Examples include polyurethane, SBR, NBR and acrylic resins. Among them, it is a preferred embodiment to use polyurethane as the main component. By using polyurethane, it is possible to obtain a sheet-like article having a solid feel, a leather-like appearance, and physical properties that can withstand actual use. Further, the term "main component" as used herein means that the mass of polyurethane is more than 50% by mass with respect to the mass of the entire elastic polymer.

When polyurethane is used in the present invention, both an organic solvent-based polyurethane that is dissolved in an organic solvent and a water-dispersed polyurethane that is dispersed in water can be used. As the polyurethane, a polyurethane obtained by reacting a polymer diol, an organic diisocyanate and a chain extender is preferably used.

Various additives such as pigments such as carbon black, flame retardants such as phosphorus-based, halogen-based and inorganic flame retardants, phenol-based, sulfur-based and phosphorus-based oxidizing UV absorbers such as inhibitors, benzotriazole-based, benzophenone-based, salicylate-based, cyanoacrylate-based and oxalic acid anilide-based light stabilizers, hindered amine-based and benzoate-based light stabilizers, hydrolysis-resistant stabilizers such as polycarbodiimide, Plasticizers, antistatic agents, surfactants, coagulation modifiers, dyes, and the like can be included.

It is important that the proportion of the elastic polymer in the sheet material is 0.01% by mass or more and 10% by mass or less, preferably 0.1% by mass or more and 8% by mass or less. If the proportion of the elastic polymer is more than 10% by mass, the texture of the sheet tends to be soft. On the other hand, if the proportion of the elastic polymer is less than 0.01% by mass, the abrasion resistance of the sheet tends to decrease.

When the elastic polymer is an organic solvent, the ratio of the elastic polymer is the weight of the nonwoven fabric remaining after the sheet is immersed in N,N'-dimethylformamide to dissolve the elastic polymer. By measuring the mass of the elastic polymer, the mass of the elastic polymer is calculated, and the mass of the sheet before immersion is divided by the mass of the dissolved elastic polymer to calculate the ratio of the elastic polymer. do. Further, when the elastic polymer is a water-dispersed system, the sheet-like material is immersed in a solvent that dissolves the fibers constituting the nonwoven fabric, and after dissolving the fibers constituting the nonwoven fabric, the remaining elastic polymer By measuring the mass and dividing the mass of the sheet-like material before immersion with respect to the mass of the elastic polymer, the ratio of the elastic polymer is calculated.

In the cross-sectional SEM image of the sheet in the thickness direction, the image area of the elastic polymer is equivalent to 0.00001 mm ² or more and 0.05 mm ² or less with respect to the image area equivalent to 0.5 mm ² of the sheet. is preferably configured to That is, in a cross section of a certain sheet-like article, the cross-sectional area ratio of the elastic polymer is preferably 0.002% or more and 10% or less with respect to the entire cross section.

If the image area of the elastic polymer is larger than 0.05 mm ² , there will be areas with a rubber-like texture. On the other hand, when the image area of the elastic polymer is smaller than 0.00001 mm ² , it is difficult to hold a plurality of single fibers, and the strength tends to decrease.

In the present invention, the image area of the elastic polymer is obtained by taking a scanning electron microscope (SEM) photograph of a cross section perpendicular to the thickness direction of the sheet containing the elastic polymer at a magnification of 100. The image area of the elastic polymer is determined by determining the location where the is present, photographing again at 500 times, and measuring the cross-sectional area of the extracted 10 locations of the elastic polymer.

[Sheet]
The apparent density of the sheet material of the present invention is preferably 0.5 g/cm ³ or more and 1.3 g/cm ³ or less, more preferably 0.6 g/cm ³ or more and 1.2 g/cm ³ or less. be. If the apparent density is lower than 0.50 g/cm ³ , the texture becomes soft and hard texture like cordovan cannot be obtained. On the other hand, if the apparent density is higher than 1.3 g/cm ³ , the sheet material becomes extremely thick, which is not suitable for practical applications such as miscellaneous goods and clothing.

The thickness of the sheet-like material of the present invention is measured according to JIS L1913:2010 "General nonwoven fabric test methods", "6.1 Thickness (ISO method)", "6.1.1 A method", and is 0.3 mm or more. 0.7 mm or less, more preferably 0.5 mm or more and 1.5 mm or less.

The basis weight of the sheet-like material of the present invention is measured by JIS L1913:2010 "General nonwoven fabric test method""6.2 Mass per unit area (ISO method)", and is 150 g / m ² or more and 2100 g / m ² or less. more preferably 300 g/m ² or more and 1950 g/m ² or less. When the basis weight is lower than 150 g/m ² , the abrasion resistance tends to decrease. On the other hand, if the basis weight is higher than 2100 g/m ² , the steric retention of the sheet-like material becomes significantly high, which is not suitable for practical use in sundries and clothing.

It is important that the cross-sectional porosity of the sheet material of the present invention is 0.1% or more and 20% or less, preferably 1% or more and 15% or less, and more preferably 2% or more and 10% or less. is. When the porosity is lower than 0.1%, the texture becomes paper-like. On the other hand, when it is higher than 20%, the texture becomes soft.

The coefficient of variation (CV) of the void ratio of the cross section of the sheet material of the present invention can also be said to be an index representing the deviation of the voids in the cross section of the sheet material, and in the present invention, it is preferably 30% or less, more preferably. is 20% or less. When the coefficient of variation (CV) is higher than 30%, the voids become uneven and the texture becomes partially soft.

The porosity of the cross section of the sheet material is obtained by taking a scanning electron microscope (SEM) photograph of the cross section perpendicular to the thickness direction of the sheet material at a magnification of 500, and binarizing the entire photograph (white area, black area). The percentage of black areas is calculated as the porosity. This is done at 10 locations, and the average value and coefficient of variation (CV) are calculated. Note that the coefficient of variation is calculated by the following formula.
- Variation coefficient of porosity (%) = (standard deviation of porosity) / (average value of porosity) x 100.

The bending resistance of the sheet-like material of the present invention is JIS L1913:2010 "General nonwoven fabric test method", "6.7 bending resistance (JIS method and ISO method)", "6.7.1 a) 41.5. ° Cantilever method (ISO method)”, using a tester (45° cantilever type tester) in which the angle from the horizontal plane of the platform of the 41.5° cantilever type tester is changed from 41.5° to 45° It refers to the value measured by The bending resistance of the sheet material of the present invention is preferably 50 mm or more and 180 mm or less, more preferably 70 mm or more and 160 mm or less. If the bending resistance is lower than 50 mm, the texture becomes soft, and hard texture like cordovan cannot be obtained. On the other hand, when the thickness is higher than 180 mm, the sheet is too hard and difficult to process such as cutting.

[Manufacturing method of sheet]
Next, a method for producing the sheet-like material of the present invention will be described.

The sheet material of the present invention can be obtained, for example, by combining the following steps. That is, (a) composite fiber web forming step, (b) nonwoven fabric (fiber entangled body) forming step, (c) ultrafine fiber forming step (nonwoven fabric densifying step), (d) polymeric elastic imparting and solidifying step, ( e) Grinding/finishing process.

In the present invention, it is preferable to use ultrafine fiber-generating fibers such as islands-in-the-sea fibers as means for obtaining a nonwoven fabric formed by entangling ultrafine fiber bundles. Although it is difficult to directly produce a nonwoven fabric from ultrafine fibers, by producing a nonwoven fabric from ultrafine fiber-generating fibers and generating ultrafine fibers from the ultrafine fiber-generating fibers in the nonwoven fabric, the ultrafine fiber bundles are entangled. A nonwoven fabric can be obtained. Further details will be described below according to this example.

(a) Step of Forming Composite Fiber Web In this step, microfiber-generating fibers (composite fibers) are conjugate-spun, and raw cotton is cut to form a composite fiber web.

As the ultrafine fiber-generating type fiber, two thermoplastic resins with different solvent solubility are used as the sea component and the island component, and the sea component is dissolved and removed using a solvent or the like to form the island component as ultrafine fiber. It is possible to employ fibers or exfoliation type conjugate fibers in which two components of thermoplastic resin are alternately arranged radially or in multiple layers on the cross section of the fibers and split into ultrafine fibers by exfoliating and splitting each component.

The sea-island type fiber includes a sea-island composite fiber that is spun by mutually arranging the two components of the sea component and the island component using a sea-island composite spinneret, and mixed spinning that is spun by mixing the two components of the sea component and the island component. However, islands-in-the-sea composite fibers are particularly useful because they can produce ultrafine fibers with a uniform fineness, and because they can produce ultrafine fibers with a sufficient length, contributing to the strength of sheet-like materials (fiber entanglement). It is preferably used.

As the sea component of the sea-island type fiber, polyethylene, polypropylene, polystyrene, copolymer polyester obtained by copolymerizing sodium sulfoisophthalic acid, polyethylene glycol, or the like, polylactic acid, or the like can be used. Polystyrene is preferable in terms of spinning stability, but copolyester having a sulfone group is preferable in that it can be easily removed without using an organic solvent.

It is important that the boiling water shrinkage ratio of the raw cotton of the ultrafine fiber-forming fiber is 20% or more and 40% or less, more preferably 25% or more and 35% or less. If the boiling water shrinkage is less than 20%, the density of the sheet will be low. On the other hand, if it is higher than 40%, the surface of the sheet is wrinkled, which is not preferable.

The shrinkage rate of the raw cotton is calculated from the rate of change in the length of the raw cotton after immersing the raw cotton (30 cm) in a shrinking tank containing boiling water for 10 minutes.

(b) Step of Forming Nonwoven Fabric (Fiber Entangled Body) Subsequently, the composite fiber web is subjected to an entanglement treatment to form a nonwoven fabric.

As a method for obtaining a nonwoven fabric, for example, a method of entangling a fiber web by needle punching or water jet punching, a spunbonding method, a melt blowing method, a papermaking method, etc. can be employed. In order to form a fiber bundle, it is important to undergo a needle punching process that enables entanglement of a composite fiber web with a high basis weight.

In the needle punching process, the number of barbs is preferably 1 or more and 9 or less. By setting the number to 1 or more, efficient entanglement of fibers becomes possible. On the other hand, fiber damage can be suppressed by setting the number to 9 or less. The number of microfiber-generating fibers caught on the barbs is determined by the shape of the barbs and the diameter of the microfiber-generating fibers. In order to hook 3 to 9 ultrafine fiber-forming fibers, the barb shape of the needle used in the needle punching process has a kick-up of 0 μm or more and 50 μm or less, an undercut angle of 0° or more and 40° or less, and a throat depth of 40 μm or more. Those having a diameter of 80 μm or less and a thread length of 0.5 mm or more and 1.0 mm or less are preferably used.

The punching number is preferably 1000/cm ² or more and 7500/cm ² or less. By setting the punching number to 1000/cm ² or more, denseness can be obtained and highly accurate finishing can be obtained. On the other hand, by setting the punching number to 7500/cm ² or less, it is possible to prevent deterioration of workability, fiber damage, and reduction in strength.

The apparent density of the nonwoven fabric made of ultrafine fiber-forming fibers after needle punching is preferably higher than 0.2 g/cm ³ and not higher than 0.7 g/cm ³ . By setting the apparent density to be higher than 0.2 g/cm ³ , the sheet-like material can obtain sufficient shape stability and dimensional stability. On the other hand, by making the apparent density lower than 0.7 g/cm ³ , it is possible to prevent needle breakage during needle punching.

(c) Step of forming ultrafine fibers (step of densifying nonwoven fabric)
Furthermore, the easily soluble polymer constituting the composite fiber is removed from the composite fiber by dissolution or by physical or chemical action to separate and split to form ultrafine fibers.

As a solvent for dissolving the easily soluble polymer (sea component) from the ultrafine fiber-forming fiber, if the sea component is a polyolefin such as polyethylene or polystyrene, an organic solvent such as toluene or trichlorethylene can be used. In the case of lactic acid or copolyester, an alkaline aqueous solution such as sodium hydroxide can be used. Further, ultrafine fiber generation processing (sea removal treatment) can be performed by immersing a nonwoven fabric made of ultrafine fiber-generating fibers in a solvent and squeezing the solution.

In order to generate ultrafine fibers from ultrafine fiber-generating fibers, known apparatuses such as a continuous dyeing machine, a vibrowasher type deseaming machine, a jet dyeing machine, a wince dyeing machine and a jigger dyeing machine can be used.

In order to further densify the nonwoven fabric formed by entangling fiber bundles, water jet punching is important. Water jet punching is preferably carried out in a columnar flow. Specifically, it is important to jet water from a nozzle having a diameter of 0.05 mm or more and 1 mm or less at a pressure of 1 MPa or more and 60 MPa or less.

The water jet punching treatment may be performed before the ultrafine fibers are generated from the ultrafine fiber-generating fibers, or may be performed after the ultrafine fibers are generated from the ultrafine fiber-generating fibers. In order to densify, it is preferable to carry out the densification after generating ultrafine fibers from the ultrafine fiber-generating fibers.

The apparent density of the nonwoven fabric obtained by water jet punching is preferably 0.5 g/cm ³ or more in order to obtain a hard texture of the sheet. It is preferably 1.1 g/cm ³ or less in order to penetrate through.

(d) Step of applying elastic polymer and solidifying The step of applying an elastic polymer containing polyurethane as a main component to the nonwoven fabric and substantially solidifying and solidifying the elastic polymer will now be described.

The elastic polymer may be applied to the nonwoven fabric before the ultrafine fibers are generated from the ultrafine fiber-generating fibers, or after the ultrafine fibers are generated from the ultrafine fiber-generating fibers. However, in order to reduce the application amount of the elastic polymer, it is preferable to apply the elastic polymer after forming ultrafine fibers from the ultrafine fiber-forming fibers.

N,N'-dimethylformamide, dimethyl sulfoxide, and the like are preferably used as a solvent for imparting polyurethane as an elastic polymer. Alternatively, a water-dispersed polyurethane liquid in which polyurethane is dispersed in water as an emulsion may be used.

The nonwoven fabric is immersed in a solution of the elastic polymer dissolved in a solvent to apply the elastic polymer to the nonwoven fabric, and then dried to substantially solidify and solidify the elastic polymer. In the case of a solvent-based polyurethane solution, it can be coagulated by immersion in an insoluble solvent, and in the case of a gelling water-dispersed polyurethane liquid, a dry coagulation method in which it is dried after gelation, etc. can be solidified. In drying, heating may be performed at a temperature that does not impair the performance of the nonwoven fabric and elastic polymer.

It is a preferable mode for excellent production efficiency to divide the obtained sheet material into half or several sheets in the sheet thickness direction after imparting the high molecular weight material to the nonwoven fabric.

(e) Grinding and densification step Finally, a step of performing a grinding treatment to densify the surface can be performed.

At least one side of the sheet material of the present invention may be ground. Grinding can be performed using sandpaper, a roll sander, or the like. In particular, by using sandpaper, a uniform and dense surface structure can be formed.

The sheet material of the present invention may contain functional agents such as dyes, pigments, softeners, anti-pilling agents, antibacterial agents, deodorants, water repellents, light stabilizers and weather stabilizers.

The sheet-like material of the present invention obtained by the manufacturing method exemplified above has a cordovan-like minute, high-class surface appearance and a hard texture, and is used for furniture, chairs, vehicle interior materials, and clothing. It can be used for a wide range of purposes.

Next, the present invention will be specifically described based on examples. However, the present invention is not limited only to these examples. In the measurement of each physical property, unless otherwise specified, the measurement was performed according to the method described above. In addition, hereinafter, "Example 4" and "Example 7", including those in Table 1, shall be read as "Reference Example 1" and "Reference Example 2", respectively.

[Measurement method and processing method for evaluation]
(1) basis weight (g/m ² )
Three samples of 50 cm in the vertical direction × 50 cm in the horizontal direction are randomly collected from the nonwoven fabric or sheet material, the mass of each sample is measured, and the average value obtained is converted to the unit area, and the decimal point is First place rounded off.

(2) Apparent density (g/cm ³ )
The thickness of the three samples collected for the basis weight measurement was measured with a dial thickness gauge (manufactured by Ozaki Seisakusho, trade name “Peacock H”), the basis weight was divided to calculate the density, and the fourth decimal place was rounded off.

(3) Average fiber length (mm)
10 fibers were pulled out from each of 3 arbitrary locations and stretched straight so as not to be stretched, and the fiber length was measured. A number average of 30 measured fiber lengths was obtained.

(4) Average single fiber diameter (μm)
The average single fiber diameter is obtained by taking a scanning electron microscope (SEM) photograph of the cross section of the sheet material, randomly selecting 10 circular or nearly circular elliptical fibers, measuring the single fiber diameter, and calculating the average of 10 fibers. Calculated by calculating the value. In the present examples and comparative examples, a scanning electron microscope "VE-7800" manufactured by Keyence Corporation was used. When ultrafine fibers with irregular cross-sections were used, first, the cross-sectional area of the single fiber was measured, and the diameter of the circle corresponding to the cross-sectional area was calculated by the following formula. The diameter thus obtained was taken as the single fiber diameter of the single fiber.
・Single fiber diameter (μm)=(4×(cross-sectional area of single fiber)/π) ^1/2 .

(5) Boiling water shrinkage (%)
The boiling water shrinkage of the raw cotton was calculated from the rate of change in length of the raw cotton (30 cm) after immersing the raw cotton in a shrinking tank containing boiling water for 10 minutes.

(6) Image area of elastic polymer (mm ² )
The image area of the elastic polymer is obtained by taking a scanning electron microscope (SEM) photograph of the cross section perpendicular to the thickness direction of the sheet containing the elastic polymer at a magnification of 100, and the maximum elastic polymer exists. The image area of the elastic polymer was determined by determining the location, photographing again at a magnification of 500, and measuring the cross-sectional area of the extracted 10 locations of the elastic polymer. In the present examples and comparative examples, a scanning electron microscope "VE-7800" manufactured by Keyence Corporation was used.

(7) Proportion of elastic polymer (%)
As described above, the sheet material is immersed in a solvent that dissolves the fibers constituting the nonwoven fabric, and after dissolving the fibers constituting the nonwoven fabric, the mass of the remaining elastic polymer is measured. By dividing the mass of the sheet before immersion by the mass, the ratio of the polymeric elastomer was calculated.

(8) Sheet material porosity (%) and coefficient of variation (CV)
A scanning electron microscope (SEM) photograph of a cross section perpendicular to the thickness direction of the sheet was taken at a magnification of 500. In the present examples and comparative examples, a scanning electron microscope "VE-7800" manufactured by Keyence Corporation was used. Next, the photographed photograph was binarized by saving it as a monochrome bitmap image using paint software, and the ratio of the black area to the entire photograph (white area, black area) was calculated using the image analysis software "ImageJ". calculated as This was done at 10 locations, and the average value and coefficient of variation of the porosity of the cross section of the sheet-like material were calculated. In addition, the coefficient of variation was calculated by the following formula.
- Variation coefficient of porosity (%) = (standard deviation of porosity) / (average value of porosity) x 100.

(9) Bending resistance of sheet (mm)
The bending resistance was measured using a 45° cantilever type tester according to the method described above.

(10) Surface Appearance of Sheet-like Material The surface appearance of the sheet-like material was evaluated visually by 20 evaluators, 10 each of healthy adult males and 10 adult females. The surface appearance was evaluated. When the number of evaluations was the same, the surface appearance of the sheet-like material was given the higher evaluation. A good level of the invention was rated as "A or B."
A: Very dense.
B: Dense.
C: Rough.
D: Very rough.

[Example 1]
<raw cotton ~ fiber entanglement>
Ultrafine fibers having a sea-island composite structure composed of island components and sea components were melt-spun under the following conditions.
・Island component: isophthalic acid-modified polyethylene terephthalate (isophthalic acid addition rate: 10%, chip intrinsic viscosity (IV value): 0.67, abbreviated as “i-PET” in Table 1)
・Sea component: Polystyrene (MFR: 2.0 g/10 min)
Spinneret: Sea-island composite spinneret with 36 islands/hole Spinning temperature: 285°C
・Island/sea mass component ratio: 55/45
・Discharge amount: 1.0 g/(min/whole)
- Spinning speed: 1100 m/min.

Then, it was stretched 3.4 times in a bath of a spinning oil solution set at 90°C. Then, after crimping using a push-type crimper, the fiber length of the conjugate fiber was cut to 51 mm to obtain raw cotton of a sea-island type conjugate fiber having a single fiber fineness of 3.8 dtex. This sea-island composite fiber had an average single fiber diameter of 15.5 μm, a crimp number of 14 crimps/inch, and a boiling water shrinkage of 35%.

Using this raw cotton, a non-woven fabric was formed through carding and cross-lapper processes. Next, needle punching was performed at 300 pre-punches/cm ² to form a nonwoven fabric (felt) having a basis mass of 1320 g/m ² . After that, a total of 2700 needle punches/cm ² were alternately performed from the upper surface side and the lower surface side to obtain a fiber entangled body having a basis mass of 1500 g/m ² and an apparent density of 0.430 g/cm ³ .

<Sheet material>
After shrinking the fiber entanglement with hot water at a temperature of 96 ° C., impregnating it with a 5% PVA (polyvinyl alcohol) aqueous solution and drying with hot air at a temperature of 110 ° C. for 10 minutes, the mass of the fiber entanglement A sheet having a PVA mass of 4% by mass was obtained. This sheet was immersed in trichlorethylene to dissolve and remove the sea component to obtain a sea-removed sheet in which ultrafine fibers were entangled. The sea-removed sheet thus obtained was subjected to a water-jet punch having a hole diameter of 0.1 mm and a nozzle head with an interval of 0.6 mm at a processing speed of 1 m/min. , 20 MPa on the front side and 20 MPa on the back side, the sheet was treated four times to remove the PVA and entangle it, and dried at 110° C. to obtain a sea-free sheet. Regarding the pressure of water ejected from the nozzle head in this water jet punching process (indicated simply as "WJP processing pressure" in Table 1), in Table 1, "Pressure (MPa)/2 The back pressure (MPa) of the third cycle/the front pressure (MPa) of the fourth cycle/the back pressure (MPa) of the fourth cycle" are shown in this order. Next, it was immersed in a 13% water-based polyurethane emulsion (“Evaphanol APC-55” manufactured by Nicca Chemical Co., Ltd.) and dried with hot air at a temperature of 110° C. for 10 minutes, so that the average single fiber diameter was 1.9 μm. A sheet substrate composed of ultrafine fibers (island component) and polyurethane was obtained.

The sheet substrate thus obtained was ground with an endless sandpaper of sandpaper count 320 to form a cordovan-like dense surface. The sheet material thus obtained has an apparent density of 0.980 g/cm ³ , a polyurethane ratio of 7%, a polyurethane image area of 0.010 mm ² , and a porosity of 7%. A sheet-like material having a coefficient of variation (CV) of 6%, a bending resistance of 142 mm, and a hard and very dense surface appearance was obtained. Table 1 shows the results.

[Example 2]
In Example 1 above, a water jet punch consisting of a nozzle head with a hole diameter of 0.1 mm and an interval of 0.6 mm was used to alternately treat the front and back at a processing speed of 1 m / min. A sheet-like material was obtained by processing under the same conditions as in Example 1, except that the treatment was performed four times with the pressure of water jetted from a nozzle head of 20 MPa. The sheet material thus obtained has an average single fiber diameter of ultrafine fibers of 1.9 μm, an apparent density of 1.072 g/cm ³ , a proportion of polyurethane in the sheet material of 7%, and a polyurethane image area of 0.010 mm ² , porosity of 3%, coefficient of variation (CV) of porosity of 3%, and bending resistance of 151 mm, giving a hard and very dense surface appearance. Table 1 shows the results.

[Example 3]
In Example 1 above, a water jet punch consisting of a nozzle head with a hole diameter of 0.1 mm and an interval of 0.6 mm was used to alternately treat the front and back at a processing speed of 1 m / min. A sheet-like material was obtained by processing under the same conditions as in Example 1, except that the treatment was performed four times with the pressure of water jetted from a nozzle head of 20 MPa. The sheet material thus obtained has an average single fiber diameter of ultrafine fibers of 1.9 μm, an apparent density of 1.168 g/cm ³ , a polyurethane content of 7% in the sheet material, and a polyurethane image area of 0.010 mm ² , a porosity of 1%, a coefficient of variation (CV) of the porosity of 1%, and a bending resistance of 156 mm, indicating a hard and very dense surface appearance. Table 1 shows the results.

[Example 4]
In Example 1 above, the mass component ratio of the island part and the sea part was 80/20, the number of islands was 16, the average single fiber diameter of the composite fiber was 19.7 μm, and the boiling water shrinkage of the raw cotton was 33%. Except for this, processing was carried out under the same conditions as in Example 1 to obtain a sheet-like material. The sheet material thus obtained has an average single fiber diameter of ultrafine fibers of 4.4 μm, an apparent density of 0.739 g/cm ³ , a proportion of polyurethane in the sheet material of 7%, and an image area of polyurethane of 0.010 mm ² , porosity of 18%, coefficient of variation (CV) of porosity of 14%, bending resistance of 116 mm, and a hard and very dense surface appearance. Table 1 shows the results.

[Example 5]
In Example 4 above, a water jet punch consisting of a nozzle head with a hole diameter of 0.1 mm and an interval of 0.6 mm was used to alternately treat the front and back at a processing speed of 1 m / min. A sheet-like material was obtained by processing under the same conditions as in Example 4, except that the treatment was performed four times with the pressure of water jetted from a nozzle head of 20 MPa. The sheet material obtained in this way has an average single fiber diameter of ultrafine fibers of 4.4 μm, an apparent density of 0.843 g/cm ³ , a high molecular weight elastomer content of 7% in the sheet material, and polyurethane. The image area was 0.010 mm ² , the porosity was 13%, the coefficient of variation of the porosity (CV) was 11%, and the bending resistance was 130 mm. Table 1 shows the results.

[Example 6]
Example 1 except that polyethylene terephthalate (intrinsic viscosity (IV value) of chip: 0.73, abbreviated as "PET" in Table 1), which is not modified with isophthalic acid, was used as the island component in Example 1 above. A sheet was obtained by processing under the same conditions as in 1. The sheet material thus obtained has an average single fiber diameter of ultrafine fibers of 1.9 μm, an apparent density of 0.954 g/cm ³ , a proportion of polyurethane in the sheet material of 9%, and a polyurethane image area of 0.010 mm ² , porosity of 14%, coefficient of variation of porosity (CV) of 14%, bending resistance of 121 mm, and a hard and dense surface appearance. Table 1 shows the results.

[Example 7]
In Example 1 above, polyamide 6 (relative viscosity (ηr): 2.70) is used as the island component, polystyrene (MFR: 2.0 g/10 min) is used as the sea component, and the mass component ratio is 40/60. A sheet was obtained by processing under the same conditions as in Example 1 except that the average single fiber diameter of the composite fiber was 23.9 μm and the boiling water shrinkage of the raw cotton was 25%. The sheet material thus obtained has an average single fiber diameter of ultrafine fibers of 1.1 μm, an apparent density of 0.568 g/cm ³ , a proportion of polyurethane in the sheet material of 9%, and a polyurethane image area of 0.010 mm ² , porosity of 17%, coefficient of variation of porosity (CV) of 14%, bending resistance of 87 mm, and a hard and dense surface appearance. Table 1 shows the results.

[Example 8]
In Example 1 above, a sheet was obtained by processing under the same conditions as in Example 1, except that the fiber length of the conjugate fiber was 85 mm. The sheet material thus obtained has an average single fiber diameter of ultrafine fibers of 1.9 μm, an apparent density of 0.872 g/cm ³ , a proportion of polyurethane in the sheet material of 9%, and a polyurethane image area of 0.010 mm ² , porosity of 16%, coefficient of variation of porosity (CV) of 14%, bending resistance of 122 mm, and a hard and dense surface appearance. Table 1 shows the results.

[Example 9]
In Example 1 above, the sea-island composite fibers obtained by melt spinning under the following conditions were collected on a net, and the sea-island composite filament web on the net was lightly pressed with a metal roll having a surface temperature of 40°C, A sea-island composite long fiber web obtained by peeling from the net was laminated with a cross-lapper and processed under the same conditions as in Example 1 except that needle punching was performed to obtain a sheet-like material. The sheet material obtained in this way has an average single fiber diameter of 1.9 μm, a fiber length of 150 mm, an apparent density of 0.895 g/cm ³ , and a polyurethane ratio of 9% in the sheet material. The image area of the polyurethane was 0.010 mm ² , the porosity was 16%, the coefficient of variation (CV) of the porosity was 15%, and the bending resistance was 135 mm. Table 1 shows the results.
・Island component: isophthalic acid-modified polyethylene terephthalate (isophthalic acid addition rate: 10%, chip intrinsic viscosity (IV value): 0.67, abbreviated as “i-PET” in Table 1)
・Sea component: Polystyrene (MFR: 2.0 g/10 min)
Spinneret: Sea-island composite spinneret with 36 islands/hole Spinning temperature: 285°C
・Island/sea mass component ratio: 55/45
・Discharge amount: 3.2g/(min/hole)
- Spinning speed: 3500 m/min (using an ejector).

[Comparative Example 1]
After dissolving and removing the sea component, a sheet was obtained by processing under the same conditions as in Example 1, except that the water jet punching treatment was not performed. The sheet material thus obtained has an average single fiber diameter of ultrafine fibers of 1.9 μm, an apparent density of 0.412 g/cm ³ , a polyurethane content of 23% in the sheet material, and a polyurethane image area of 0.015 mm ² , a porosity of 25%, a coefficient of variation (CV) of the porosity of 21%, and a bending resistance of 41 mm. Table 1 shows the results.

[Comparative Example 2]
After dissolving and removing the sea component, a sheet was obtained by processing under the same conditions as in Example 8, except that the water jet punching treatment was not performed. The sheet material thus obtained has an average single fiber diameter of ultrafine fibers of 1.1 μm, an apparent density of 0.342 g/cm ³ , a proportion of polyurethane in the sheet material of 33%, and a polyurethane image area of 0.015 mm ² , porosity of 30%, coefficient of variation (CV) of porosity of 21%, bending resistance of 38 mm, and soft texture and rough surface appearance. Table 1 shows the results.

As shown in Examples 1 to 9 in Table 1, when the water jet punching treatment was performed after dissolving and removing the sea component, the porosity of the sheet material was 0.1% or more and 20% or less and the polymer elastic body Since the ratio is 10% or less, a sheet-like material having a hard and dense surface appearance is obtained.

On the other hand, as shown in Comparative Examples 1 and 2 in Table 2, when the water jet punching treatment is not performed after dissolving and removing the sea component, the porosity of the sheet material and the proportion of the elastic polymer material increase. Therefore, a sheet-like material having a supple texture and a rough surface appearance is obtained.

As shown in Examples 1 and 4, and Examples 2 and 5 in Table 1, when the components and processing conditions are the same, the smaller the average single fiber diameter, the more densely the fibers are laminated, forming a sheet. The porosity of the product is 10% or less, the bending resistance is 140 mm or more, and the sheet-like product has a harder and denser surface appearance.

Moreover, as shown in Examples 1 and 9 in Table 1, a sheet-like material having a hard and dense surface appearance can be obtained by using either the short-fiber nonwoven fabric or the long-fiber nonwoven fabric. When a staple fiber nonwoven fabric is used, a sheet-like material having a hard and very dense surface appearance is obtained.

The sheet-like material of the present invention has a cordovan-like, dense and luxurious surface appearance and a hard material feel, and can be widely used for furniture, chairs, vehicle interior materials, and clothing.

Claims (7)

A sheet-shaped article comprising a nonwoven fabric comprising a fiber entangled body and an elastic polymer, wherein the proportion of the elastic polymer is 0.01% by mass or more and 10% by mass or less, and the sheet-like article has an apparent density of 0. 843 g/cm ³ or more and 1.3 g/cm ³ or less, and a cross-sectional porosity of the sheet material of 0.1% or more and 16% or less. 2. The sheet-like material according to claim 1, wherein the average fiber length of fibers constituting said nonwoven fabric is 15 mm or more and 90 mm or less. In the cross-sectional SEM image of the sheet in the thickness direction, the image area of the elastic polymer is equivalent to 0.00001 mm ² or more and 0.05 mm ² or less with respect to the image area equivalent to 0.5 mm ² of the sheet. 3. The sheet material according to claim 1 or 2. The sheet material according to any one of claims 1 to 3, having a bending resistance of 50 mm or more and 180 mm or less. The sheet material according to any one of claims 1 to 4, wherein the coefficient of variation (CV) of the porosity of the cross section of the sheet material is 30% or less. The sheet according to any one of claims 1 to 5, wherein the fibers constituting the nonwoven fabric are made of at least one selected from polyethylene terephthalate, polyamide 6 and copolymers thereof. shape. The method for producing a sheet-like material according to any one of claims 1 to 6, comprising (a) a nonwoven fabric (fiber entangled body) forming step and (b) a nonwoven fabric densifying step,
The (a) nonwoven fabric (fiber entangled body) forming step is a step of forming a nonwoven fabric by needle-punching a fibrous web made of raw cotton having a boiling water shrinkage of 20% or more and 40% or less,
The (b) nonwoven fabric densification step is a step of subjecting the nonwoven fabric to water jet punching at a pressure of 1 MPa or more and 60 MPa or less.
A method for producing a sheet-like article.