JP2007119936A - Substrate for leather-like sheet material and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for obtaining a leather-like sheet material excellent in appearance, hand and physical properties without inhibiting migration with an organic solvent-free polyurethane aqueous dispersion, and to provide a method for producing the same. <P>SOLUTION: This artificial leather-like substrate comprising a nonwoven fabric prepared by interlacing ultra fine fibers having a single fiber fineness of 0.001 to 0.5 dtex and a self-emulsifiable polyurethane having a softening point of 70 to 150°C and contained in the nonwoven fabric is characterized in that the ultra fine fibers constituting the non-woven fabric are interlaced with each other, and the total weight of the polyurethane existing from the surface to 1/3 of the depth in the sheet thickness direction is 70 to 100 wt.% based on the total weight of the polyurethane existing in the whole body of the substrate. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a base material for leather-like sheet material for producing a leather-like sheet material excellent in appearance, texture and physical properties using an aqueous polyurethane dispersion, and a method for producing the same.

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

  In producing such a leather-like sheet, after impregnating a nonwoven fabric with an organic solvent solution of polyurethane, the fiber sheet is immersed in water or an organic solvent aqueous solution, which is a non-solvent of polyurethane, to wet the polyurethane. A method of solidifying is generally adopted. As such an organic solvent, a water-miscible organic solvent such as N, N'-dimethylformamide is used. However, since organic solvents are 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 leather-like sheets.

  As a specific solution, for example, a method using a polyurethane water dispersion in which polyurethane is dispersed in water instead of the conventional organic solvent type polyurethane has been studied.

  However, in such a method, after impregnating the polyurethane aqueous dispersion into the sheet, the polyurethane migrates to the surface as the water evaporates during drying, so that a so-called migration phenomenon occurs, the polyurethane is localized on the sheet surface, It has been difficult to obtain a leather-like sheet that can withstand practical use due to degradation in quality and texture.

  In order to obtain a flexible texture, means for preventing the migration phenomenon have been studied.

  For example, in Patent Document 1, heat-sensitive gelling properties are imparted by adding inorganic salts to a polyurethane water dispersion. Due to the heat-sensitive gelation property, the polyurethane gels before being transferred to the sheet surface during drying to suppress migration and soften the texture. However, this method has a problem in productivity because there is concern about the stability of the polyurethane liquid.

In Patent Document 2, an attempt is made to suppress migration by uniformly applying heat to the entire sheet by drying using an infrared plate heater after impregnation with polyurethane emulsion. However, this method is not versatile because it requires special equipment in the drying stage.
Patent Document 3 describes a method in which a polyurethane emulsion having heat-sensitive gelling properties is impregnated, solidified in a hot water bath, and then dried in a hot air drier. In this method, the polyurethane emulsion is immersed in hot water. The elution cannot be suppressed, and there is a problem of a decrease in physical properties due to a substantial decrease in the polyurethane content, and an increase in cost due to an increase in the polyurethane content to compensate for it.

That is, at present, there has been no method for obtaining a leather-like sheet-like material excellent in appearance, texture and physical properties using a polyurethane aqueous dispersion that does not use an organic solvent.
JP-A-6-316877 JP 59-42110 A JP 2000-96457 A

  In view of the background of such prior art, the present invention provides a leather for obtaining a leather-like sheet-like material excellent in appearance, texture, and physical properties, without suppressing migration, using a polyurethane aqueous dispersion containing no organic solvent. A sheet-like substrate and a method for producing the same are provided.

  That is, the base material for leather-like sheet material of the present invention has a softening point of 70 ° C. or higher and 150 ° C. or lower on a nonwoven fabric formed by entanglement of ultrafine fibers having a single fiber fineness of 0.001 dtex or more and 0.5 dtex or less A base material for leather-like sheet-like material containing self-emulsifying polyurethane, in which single fibers of ultrafine fibers constituting the nonwoven fabric are intertwined, and a depth of 1/3 from the surface with respect to the thickness direction of the base material A leather-like sheet-like substrate is characterized in that the total weight of polyurethane present so far is 70% by weight to 100% by weight of the total weight of polyurethane present in the entire sheet.

  Further, the base material for leather-like sheet material of the present invention is “a method for producing the above-mentioned base material for leather-like sheet material, wherein ultrafine fibers having a single fiber fineness of 0.001 dtex or more and 0.5 dtex or less are pressurized. “A method for producing a base material for leather-like sheet-like material, which comprises impregnating a nonwoven fabric entangled with a water stream with a self-emulsifying polyurethane having a softening point of 70 ° C. or higher and 150 ° C. or lower and drying”.

  According to the present invention, using a polyurethane aqueous dispersion containing no organic solvent, a leather-like sheet-like base for obtaining a leather-like sheet having excellent appearance, texture, and physical properties without suppressing migration. A material and its manufacturing method can be obtained.

The base material for leather-like sheet-like material of the present invention has a non-woven fabric formed by intertwining ultrafine fibers having an average single fiber fineness of 0.001 dtex or more and 0.5 dtex or less, and an elastic resin binder. The self-emulsifying polyurethane having a softening point of 70 ° C. or higher and 150 ° C. or lower.
Examples of the ultrafine fibers constituting the nonwoven fabric constituting the base material for leather-like sheet of the present invention include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polylactic acid, 6-nylon, 66-nylon, etc. Various synthetic fibers such as polyamide and acrylic can be used. Among these, polyester fibers are preferably used from the viewpoints of strength, dimensional stability, and light resistance.

  Further, the nonwoven fabric may be configured by mixing ultrafine fibers of different materials, and a woven fabric or a knitted fabric may be inserted into the nonwoven fabric for the purpose of improving the strength.

  It is important that the average single fiber fineness of the ultrafine fibers constituting the nonwoven fabric is 0.001 dtex or more and 0.5 dtex or less from the viewpoint of sheet flexibility and napped quality. Preferably it is 0.3 dtex or less, More preferably, it is 0.2 dtex or less. On the other hand, it is preferably 0.005 dtex or more, more preferably 0.01 dtex or more, from the viewpoint of dispersibility of fibers during raising process such as coloring after dyeing or grinding with sandpaper, and ease of spreading. .

  In addition, the average single fiber fineness of the ultrafine fibers constituting the non-woven fabric was obtained by taking a scanning electron microscope (SEM) photograph of the surface of the leather-like sheet-like substrate (or non-woven fabric) at a magnification of 2000 times, and circular or nearly circular It is calculated by selecting 100 elliptical fibers at random, measuring the fiber diameter, converting the specific gravity of the material polymer into the fineness, and calculating the average value.

  Regarding the uniformity of the fineness of the ultrafine fibers constituting the nonwoven fabric, the fineness CV in the fiber bundle is preferably 10% or less. Here, the fineness CV is a percentage (%) of a value obtained by dividing the fineness standard deviation of the fibers constituting the fiber bundle by the average fineness in the bundle, and indicates that the smaller the value, the more uniform. . When the fineness CV is set to 10% or less, the appearance of napping on the surface of the leather-like sheet obtained by dyeing the leather-like sheet-like substrate of the present invention is elegant, and the dyeing is homogeneous and good. It can be.

  The cross-sectional shape of the ultrafine fiber may be a round cross-section, but may be a polygonal shape such as an ellipse, a flat shape, or a triangle, or an irregular cross-section such as a sector shape or a cross shape. In addition, the fineness CV in the case of an irregular cross section is calculated based on the outer circumference circle of the irregular cross section.

  The nonwoven fabric constituting the base material for leather-like sheet material of the present invention may be either a short fiber nonwoven fabric or a long fiber nonwoven fabric, but a short fiber nonwoven fabric is preferred when emphasis is placed on texture and quality. Similarly, when emphasis is placed on the texture and quality, the fiber length of the short fibers is preferably 25 mm or more and 90 mm or less in consideration of wear resistance due to entanglement.

  The nonwoven fabric constituting the base material for leather-like sheet material of the present invention must be one in which single fibers of ultrafine fibers are intertwined. Since the ultrafine fibers are intertwined with each other, the denseness of the nonwoven fabric is improved, the quality of the sheet-like material is improved, and physical properties such as wear resistance and tensile strength are further improved. Whether the ultrafine fibers are intertwined can be confirmed by observation with a scanning electron microscope (SEM).

  In the present invention, such a nonwoven fabric is impregnated with a self-emulsifying polyurethane having a softening point of 70 ° C. or more and 150 ° C. or less as an elastic resin binder, and the self-emulsifying polyurethane is present in the internal space of the nonwoven fabric. It is what.

  The polyurethane water dispersion used in the production of the present invention is a polyurethane water dispersion dispersed in water as an emulsion, and is a self-emulsifying polyurethane water dispersion containing no emulsifier such as a surfactant. When a forced emulsification type polyurethane aqueous dispersion containing an emulsifier such as a surfactant is used, the surface of the obtained base material for leather-like sheet-like material generates stickiness or the like due to the emulsifier. This increases the number of processing steps and increases costs.

The self-emulsifying polyurethane is not particularly limited as long as it is an aqueous dispersion dispersed in water, but a polycarbonate-based self-emulsifying polyurethane aqueous dispersion is preferable.
The polyurethane water dispersion used in the present invention is a self-emulsifying polyurethane water dispersion, but the self-emulsifying polyurethane water dispersion is a polyurethane in which water is stably dispersed without using an emulsifier such as a surfactant. It is an aqueous dispersion, and has a hydrophilic so-called internal emulsifier in the self-emulsifying polyurethane molecular structure.
The self-emulsifying polyurethane is usually handled in a state of being dispersed in water, and can be obtained from the manufacturer in this state. This is because once dried, it cannot be dispersed in water again.
The internal emulsifier may be any of a cationic system such as a quaternary amine salt, a nonionic system such as polyethylene glycol, or an anionic system such as a sulfonate or carboxylate. However, the cationic internal emulsifier is resistant to light such as yellowing. Since it is inferior, it is preferable that they are nonionic or anionic.
As the self-emulsifying polyurethane used in the present invention, those having a structure in which polyol, polyisocyanate, and chain extender are appropriately reacted in addition to the internal emulsifier can be used.

  Here, as the polyol, a polycarbonate diol, a polyester diol, a polyether diol, a silicone diol, or a copolymer combining these may be used. Among these, polycarbonate diol is preferably used from the viewpoint of durability.

The polycarbonate-based diol can be produced by an ester exchange reaction between an alkylene glycol and a carbonate ester, or a reaction between phosgene or chloroformate ester and an alkylene glycol. Examples of the alkylene glycol include linear alkylene glycol such as ethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10 decanediol, Examples include branched alkylene glycols such as neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, and 2-methyl-1,8-octanediol. 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 polyisocyanate include aliphatic systems such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and xylylene diisocyanate, and aromatic systems such as diphenylmethane diisocyanate and tolylene diisocyanate, and combinations thereof. Also good. Among these, aliphatic systems such as dicyclohexylmethane diisocyanate are preferable from the viewpoint of light resistance.
Further, as the chain extender, amine type such as ethylenediamine and methylenebisaniline, diol type such as ethylene glycol, and polyamine obtained by reacting polyisocyanate with water can be used.

  In the present invention, the self-emulsifying polyurethane may be used alone or in combination of two or more, and other polymers may be used in combination.

Examples of other polymers include water-dispersible and water-soluble polymers such as acrylic and silicone.
Further, the polyurethane water dispersion used in the present invention includes carbon black and other pigments, dyes, fungicides, antioxidants and ultraviolet absorbers, flame retardants, penetrants and lubricants, silica and titanium oxide, etc. It may contain a surfactant such as an antiblocking agent, an antistatic agent, an antifoaming agent such as silicone, a filler such as cellulose, a coagulation modifier, and the like.
The softening point of the self-emulsifying polyurethane must be 70 ° C or higher and 150 ° C or lower. Since the softening point of polyurethane can be controlled by adjusting a combination of polyol and isocyanate, a cross-linking agent, etc., in producing polyurethane, the softening point is adjusted to 70 ° C. by adjusting the combination of polyol, isocyanate and cross-linking agent. The temperature may be in the range of 150 ° C. or lower. When the softening point is within this range, an appropriate self-emulsifying polyurethane is dropped during the dyeing process, and a soft, yet napped long leather-like sheet-like material is obtained. Moreover, the effect which lose | disappears the stripe | line | stripe which expresses in the process of entanglement | strengthening of the single fiber of an ultrafine fiber by moderate drop | exfoliation of a self-emulsification type polyurethane can also be anticipated.
Napped long-toned leather-like sheet impregnated with self-emulsifying polyurethane with a softening point of less than 70 ° C. has a significant dropout of the self-emulsifying polyurethane during the dyeing process, resulting in a decrease in strength and deterioration of texture due to lack of fullness. . On the other hand, the napped long leather-like sheet-like material impregnated with a self-emulsifying polyurethane having a softening point exceeding 150 ° C. hardly loses the self-emulsifying polyurethane in the dyeing process, and the texture becomes hard. Furthermore, since the surface state is almost the same as that before the dyeing process, streaks appearing in the process of entanglement of the single fibers of the ultrafine fibers cannot be eliminated.

The softening point is measured by the following method. That is, a 100 μm-thick film obtained by drying the self-emulsifying polyurethane aqueous dispersion at 50 ° C. is cut into 1 cm × 5 cm (width × length) and suspended in a dryer. Heating at 5 ° C./min with a 10 g weight attached to the bottom of the film, the temperature when the weight position is lowered 3 cm from the start position is taken as the softening point.

In the base material for leather-like sheet of the present invention, the content of the self-emulsifying polyurethane with respect to the total weight of the base material is preferably 10% by weight or more and 50% by weight or less. More preferably, it is 15 to 35 weight%. By making it 10% by weight or more, it is possible to obtain sheet strength and prevent the fibers from falling off, and by making it 50% by weight or less, it is possible to prevent the texture from becoming hard and to achieve the desired good raised quality. Obtainable. More preferably, it is 15 weight% or more and 40 weight% or less.
Moreover, as a form inside the base material for leather-like sheet-like materials of self-emulsifying polyurethane, from the surface to the depth of 1/3 (hereinafter referred to as surface layer 1/3) with respect to the thickness direction of the base material. The total weight of the self-emulsifying polyurethane present in (1) must be 70% by weight or more and 100% by weight or less of the total weight of the self-emulsifying polyurethane present in the entire substrate. A base material having a content of less than 70% by weight tends to deteriorate the wear resistance because the amount of self-emulsifying polyurethane near the surface after dyeing is too small to hold fibers. Preferably it is 75 weight% or more, More preferably, it is 80 weight% or more.

  The weight of the self-emulsifying polyurethane can be calculated from the difference in weight by slicing the base material for leather-like sheet material into three sheets with the same thickness in the thickness direction, extracting the self-emulsifying polyurethane with an organic solvent such as trichlene, etc. .

  Next, the manufacturing method of the base material for leather-like sheet material of this invention is demonstrated.

  The means for obtaining the ultrafine fibers constituting the nonwoven fabric is not particularly limited, but it is preferable to use ultrafine fiber generating fibers. A nonwoven fabric in which ultrafine fibers are entangled can be obtained by performing ultrafine fiber after entanglement of ultrafine fiber generating fibers in advance.

  As ultra-fine fiber generation type fibers, two-component thermoplastic resins with different solvent solubility are used as sea components and island components, and the sea components are dissolved and removed using a solvent, etc., so that the island components are made into ultra-fine fibers. It is possible to employ a peelable composite fiber that splits fibers into ultrafine fibers by alternately disposing fibers or two-component thermoplastic resin in a radial or multilayered cross section and separating each component. Above all, the sea-island type composite fiber can provide an appropriate gap between island components, that is, between the ultrafine fibers inside the fiber bundle by removing the sea component, so from the viewpoint of flexibility and texture of the base material. preferable.

  For the sea-island type composite fiber, a sea-island type composite base is used, and a polymer inter-array system in which the two components of the sea and the island are mutually arranged and spun, and the mixed spinning in which the two components of the sea and the island are mixed and spun. Although a system etc. can be used, the sea island type composite fiber by a polymer array system is more preferable at the point from which the ultrafine fiber of uniform fineness is obtained.

  As the sea component of the sea-island composite fiber, polyethylene, polypropylene, polystyrene, copolymerized polyester obtained by copolymerizing sodium sulfoisophthalic acid, polyethylene glycol, or the like, polylactic acid, or the like can be used.

  As the solvent for dissolving the sea component, an organic solvent such as toluene or trichloroethylene in the case of polyethylene, polypropylene, or polystyrene, and an alkaline aqueous solution such as sodium hydroxide can be used in the case of the copolymerized polyester or polylactic acid. It can be removed by immersing the sea-island composite fiber in it and applying a stenosis solution.

  The obtained ultrafine fiber-generating fiber is preferably crimped and cut to a predetermined length to obtain a nonwoven raw cotton. A known method can be used for crimping or cutting. The obtained raw cotton is made into a web with a cross wrapper or the like, and then the fibers are entangled to make a nonwoven fabric.

  As a method of obtaining a nonwoven fabric by entanglement of fibers, a method of entanglement by a water jet punch is preferable. Alternatively, a method is used in which ultrafine fiber-generating fibers are entangled with each other by a needle punch, and after the fibers are ultrafinened, single fibers of the ultrafine fibers are entangled with each other by a water jet punch.

  In applying the self-emulsifying polyurethane aqueous dispersion to the nonwoven fabric in which the single fibers of the ultrafine fibers are entangled with each other, a method of impregnating or applying the polyurethane aqueous dispersion to the nonwoven fabric and dry heat coagulation, There is a method of impregnating the polyurethane aqueous dispersion, then coagulating with heat and heat and drying by heating, and combinations thereof, but there is no particular limitation. In order to prevent the polyurethane from being concentrated on the surface layer 1/3, that is, to suppress the migration, a polyurethane having a heat-sensitive gel property is used as in Patent Document 2, or is dried with an infrared heater or the like as in Patent Document 3. However, in the present invention, there is no need to perform such an operation. If polyurethane is applied by a known method, it is possible to obtain a material in which most of the polyurethane is present in the surface layer 1/3.

  If the drying temperature is too low, the drying time will be long, and if it is too high, it may cause thermal degradation of the self-emulsifying polyurethane, so that it is preferably 80 ° C. or higher and 150 ° C. or lower. More preferably, it is 90 degreeC or more and 140 degrees C or less.

  When applying a self-emulsifying polyurethane aqueous dispersion, pigments such as carbon black, dyes, fungicides, light-proofing agents such as antioxidants and UV absorbers, flame retardants, penetrants and lubricants, silica Anti-blocking agents such as titanium oxide, surfactants such as antistatic agents, antifoaming agents such as silicone, fillers such as cellulose, coagulation regulators, and the like can be used.

The base material for leather-like sheet-like material of the present invention may be a base material for leather-like sheet-like material having a nap-like tone that has napped fibers of at least one surface.
The raising treatment for forming napping on the surface of the base material for leather-like sheet material can be performed by a method of grinding using sandpaper, roll sander or the like. A lubricant such as a silicone emulsion may be applied before the raising treatment.
In addition, it is preferable to apply an antistatic agent before the raising treatment, because the grinding powder generated from the leather-like sheet-like substrate by grinding tends to be difficult to deposit on the sandpaper.
Further, the base material for leather-like sheet-like material may be obtained by dividing into half or several sheets in the sheet thickness direction before performing the raising treatment.
The base material for leather-like sheet material of the present invention is for obtaining a leather-like sheet material dyed in a desired color by dyeing. The dyeing method dyes the base material for leather-like sheet material, and at the same time gives a stagnation effect, softens the base material, and can appropriately drop the self-emulsifying polyurethane. preferable. As the liquid dyeing machine, a known liquid dyeing machine can be used.

  It is one of preferred embodiments that 1 to 5% by weight of the self-emulsifying polyurethane is removed from the base material for leather-like sheet by dyeing with a liquid dyeing machine. Thereby, the brushing of the surface of the leather-like sheet is improved, and at the same time the texture is softened. If the drop-off amount is less than 1% by weight, such an improvement effect is small, and if it exceeds 5% by weight, the inside of the dyeing machine becomes dirty and the sheet becomes defective or the physical properties are lowered. Factors that influence the amount of dropout include the running speed of the substrate in the dyeing machine, the nozzle diameter of the dyeing machine, the dyeing temperature, and the dyeing time. In order to control the amount of falling off, it is necessary to optimize according to the characteristics of the base material for leather-like sheet. For example, when the amount of self-emulsifying polyurethane is relatively small, mild conditions such as slowing the substrate running speed, increasing the nozzle diameter of the dyeing machine, lowering the dyeing temperature, dyeing time, etc. In contrast, in the case of a base material having a large amount of self-emulsifying polyurethane, it is necessary to change the respective conditions in the opposite direction.

If the dyeing temperature is too high, the self-emulsifying polyurethane may be deteriorated. Conversely, if the dyeing temperature is too low, the dyeing to the fibers becomes insufficient. The following is preferable, and 110 ° C. or higher and 130 ° C. or lower is more preferable.
The dye is not particularly limited and may be selected according to the ultrafine fiber constituting the nonwoven fabric. For example, a dye such as a disperse dye is used for a polyester ultrafine fiber, and an acid dye or a metal-containing dye is used for a polyamide ultrafine fiber. Can do.

  When dyed with disperse dyes, reduction washing may be performed after dyeing.

  Moreover, it is preferable to use a dyeing assistant during dyeing for the purpose of improving the uniformity and reproducibility of dyeing. Further, a finishing agent treatment such as a softening agent such as silicone or an antistatic agent may be applied, and the finishing treatment may be performed after dyeing or in the same bath as dyeing.

  The leather-like sheet-like material obtained by dyeing the leather-like sheet-like substrate of the present invention is used for furniture, chairs, wall materials, seats, ceilings, interiors, etc. in vehicles such as automobiles, trains, and aircraft. It can be suitably used as an interior material having a very elegant appearance as a skin material, a material for clothing such as a shirt, a jacket, shoes, and a bag.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely using an Example, this invention is not limited only to a following example.
[Evaluation methods]
(1) Average single fiber fineness A scanning electron microscope (SEM) photograph of the surface of a non-woven fabric or leather-like sheet-like material was taken at a magnification of 2000 times, and 100 circular or nearly elliptical fibers were randomly selected. The fiber diameter was selected, the fiber diameter was converted to the fineness from the specific gravity of the fiber material polymer, and the average value of 100 was calculated.

(2) Fineness CV
A cross-section inside a nonwoven fabric or leather-like sheet-like substrate is observed with a scanning electron microscope (SEM) at a magnification of 2000 times, and from the photograph, an ultrafine fiber constituting one bundle of bundle fibers is observed. The fiber diameter was measured, converted to the fineness of each single fiber from the fiber diameter, and the value obtained by dividing the fineness standard deviation of the fibers constituting the fiber bundle by the average fineness within the bundle was expressed as a percentage (%). The same measurement was performed on the five bundle fibers, and the average value was defined as the fineness CV.

(3) Confirmation of entanglement between single fibers The surface of the nonwoven fabric or the base material for leather-like sheet-like material is observed with a scanning electron microscope (SEM) at a magnification of 300 times to confirm entanglement between single fibers. did.

(4) Appearance quality The surface quality of the leather-like sheet obtained by dyeing the base material for leather-like sheet was evaluated by visual inspection and sensory evaluation as follows. A good level of the present invention was set to “◯” or more. A: Napped length and fiber dispersion state are very good.
○: Napped length and fiber dispersion state are good.
X: Napped length is good, but fiber dispersion is poor.
XX: Napped length is short and defective.
XXX: There is almost no napping and it is a remarkable defect.

(5) Bending softness The bending softness of the leather-like sheet obtained by dyeing the base material for leather-like sheet was performed according to JIS P8125: 2000. The good level of the present invention was set to 0.30 mN / m or less.

(6) Softening point of self-emulsifying polyurethane A 100 μm thick film obtained by drying a self-emulsifying polyurethane aqueous dispersion at 50 ° C. is cut into 1 cm × 5 cm (width × length) and suspended in a dryer. did. Heating was performed at 5 ° C./min with a 10 g weight attached to the lower part of the film, and the temperature when the weight position dropped 3 cm from the start position was defined as the softening point.

(7) Self-emulsifying polyurethane content distribution 5 cm x 5 cm (width x length) leather-like sheet-like base material is sliced into three pieces with the same thickness in the thickness direction, and polyurethane is extracted with an organic solvent such as trichlorethylene The self-emulsifying polyurethane content of each substrate is calculated from the weight difference. By comparing the self-emulsifying polyurethane content of the three sliced sheets of the surface layer portion and the entire three sliced sheets, it exists in the surface layer 1/3 with respect to the weight of the self-emulsifying polyurethane of the whole substrate The ratio of the weight of the self-emulsifying polyurethane was calculated.

(8) Pilling Evaluation The pilling evaluation of the leather-like sheet obtained by dyeing the leather-like sheet-like base material was carried out by James H. as a Martindale abrasion tester. Heal & Co. The model 406 made by using the company's ABRASIVE CLOTH SM25 as a standard friction cloth, a load equivalent to 12 kPa was applied, and the appearance of the sample after being rubbed under conditions of 20,000 wear times was visually observed and evaluated. . The evaluation criteria were grade 5 when the appearance of the sample was not changed from before friction, grade 1 when the appearance of many hairballs was graded, and the grade was divided by 0.5 grade. Moreover, the pass level in this invention was made into the 4th grade or more.

[Polyurethane type]
The self-emulsifying polyurethane aqueous dispersions used in Examples and Comparative Examples are as follows. The concentration of the polyurethane water dispersion was 10% by weight.

(1) Self-emulsifying polyurethane water dispersion I
A. Polyurethane composition Polyisocyanate: Hexamethylene diisocyanate Polyol: Poly (3-methylpentane carbonate)
Internal emulsifier: dimethylolpropionic acid triethylamine salt Chain extender: water (diamine obtained by reaction of isocyanate and water)
Internal cross-linking agent: none Softening point: 120 ° C
(2) Self-emulsifying polyurethane water dispersion II
A. Polyisocyanate: Hexamethylene diisocyanate
Polyol: Polytetramethylene glycol
Internal emulsifier: dimethylolpropionic acid triethylamine salt
Chain extender: Water (diamine obtained by reaction of isocyanate and water)
Internal cross-linking agent: none Softening point: 85 ° C
(3) Self-emulsifying polyurethane water dispersion III
A. Polyisocyanate: Dicyclohexylmethane diisocyanate
Polyol: Poly (3-methylpentane carbonate)
Internal emulsifier: dimethylolpropionic acid triethylamine salt
Chain extender: Water (diamine obtained by reaction of isocyanate and water)
Internal cross-linking agent: none Softening point: 140 ° C
(4) Self-emulsifying polyurethane water dispersion IV
A. Polyisocyanate: Hexamethylene diisocyanate
Polyol: Poly (3-methylpentane carbonate)
Internal emulsifier: dimethylolpropionic acid triethylamine salt
Chain extender: Water (diamine obtained by reaction of isocyanate and water)
Internal cross-linking agent: diamine compound having silanol group Softening point: 180 ° C
(5) Self-emulsifying polyurethane water dispersion V
A. Polyisocyanate: Hexamethylene diisocyanate
Polyol: Poly (2-methyltetramethylene glycol)
Internal emulsifier: dimethylolpropionic acid triethylamine salt
Chain extender: Water (diamine obtained by reaction of isocyanate and water)
Internal cross-linking agent: none Softening point: 60 ° C
(6) Self-emulsifying polyurethane water dispersion VI
A. Polyurethane composition Polyisocyanate: Hexamethylene diisocyanate Polyol: Poly (3-methylpentane carbonate)
Internal emulsifier: dimethylolpropionic acid triethylamine salt Chain extender: water (diamine obtained by reaction of isocyanate and water)
Internal cross-linking agent: None Additive: Sodium sulfate (Na ₂ SO ₄ )
B. Softening point: 115 ° C
[Example 1]
Sea-island composite fibers were spun at a composite ratio of 55% by weight of sea component and 45% by weight of island component, using polystyrene as the sea component, polyethylene terephthalate as the island component, and a sea-island type composite base having 16 islands. Thereafter, stretching, crimping, and cutting to 51 mm were performed to obtain a nonwoven fabric raw cotton. The obtained raw cotton was made into a web using a cross wrapper and made into a nonwoven fabric by needle punching.

  The nonwoven fabric composed of this sea-island type composite fiber was impregnated with a 10% aqueous solution of polyvinyl alcohol having a saponification degree of 87% and then dried. Thereafter, polystyrene, which is a sea component, was extracted and removed from trichlorethylene and dried to obtain a nonwoven fabric in which fiber bundles made of ultrafine fibers having an average single fiber fineness of 0.1 dtex were intertwined.

  The fineness CV was 7.4%.

  The nonwoven fabric was subjected to a water jet punching process and entangled while removing polyvinyl alcohol.

  The surface of the nonwoven fabric thus obtained was observed with a scanning electron microscope (SEM), and it was confirmed that the single fibers were intertwined.

  This non-woven fabric is immersed in the self-emulsifying polyurethane water dispersion I, and the amount of the self-emulsifying polyurethane water dispersion is adjusted with a squeeze roll and then dried. A 20% by weight sheet was obtained.

  One side of the obtained sheet-like material was subjected to raising treatment by grinding using a 180 mesh endless sandpaper to obtain a leather-like sheet-like substrate of the present invention. The weight of the self-emulsifying polyurethane present in the surface layer 1/3 of the obtained base material for leather-like sheet was 93% by weight with respect to the weight of the self-emulsifying polyurethane of the whole base material.

  The leather-like sheet-like material obtained by dyeing the obtained leather-like sheet-like substrate with a disperse dye using a liquid dyeing machine at 125 ° C. for 45 minutes has good appearance quality and flexibility. The pilling evaluation was good.

[Example 2]
Except for using the self-emulsifying polyurethane aqueous dispersion II having a softening point of 85 ° C., the same treatment as in Example 1 was performed to obtain the base material for leather-like sheet material of the present invention in which single fibers were entangled with each other. It was. The weight of the self-emulsifying polyurethane present in the surface layer 1/3 of the obtained base material for leather-like sheet was 82% by weight with respect to the weight of the self-emulsifying polyurethane of the whole base material.
The leather-like sheet material obtained by dyeing the obtained leather-like sheet material substrate in the same manner as in Example 1 had good appearance quality and very good flexibility. Moreover, pilling evaluation was favorable.

[Example 3]
For the leather-like sheet material of the present invention in which single fibers were entangled with each other except that nylon 6 was used as the island component and self-emulsifying polyurethane aqueous dispersion III was used. A substrate was obtained. The average single fiber fineness was 0.1 dtex, and the fineness CV was 7.8%. The weight of the self-emulsifying polyurethane present in the surface layer 1/3 of the base material for leather-like sheet was 90% by weight with respect to the weight of the self-emulsifying polyurethane of the whole base material.

  Further, the leather-like sheet-like material obtained by dyeing the obtained leather-like sheet-like substrate in the same manner as in Example 1 has good appearance quality and flexibility, and the pilling evaluation is good. there were.

[Comparative Example 1]
Except for using the self-emulsifying polyurethane aqueous dispersion IV, the same treatment as in Example 1 was performed to obtain a leather-like sheet-like base material for comparison. The weight of the self-emulsifying polyurethane present in the surface layer 1/3 of the base material for leather-like sheet was 91% by weight with respect to the weight of the self-emulsifying polyurethane of the whole base material.

  Moreover, although the pilling evaluation of the sheet-like material obtained by dyeing the obtained leather-like sheet-like substrate in the same manner as in Example 1 was good, the appearance was poor and the flexibility was very high. It was hard.

[Comparative Example 2]
Except for using the self-emulsifying polyurethane water dispersion V, the same treatment as in Example 1 was performed to obtain a leather-like sheet-like base material for comparison. The weight of the self-emulsifying polyurethane present in the surface layer 1/3 of the base material for leather-like sheet was 85% by weight with respect to the weight of the self-emulsifying polyurethane of the whole base material.

  Further, the sheet-like material obtained by dyeing the obtained leather-like sheet-like substrate in the same manner as in Example 1 was very flexible, but the appearance was poor and the pilling evaluation was also good. It was a bad result.

[Comparative Example 3]
A base material for leather-like sheet material for comparison was obtained by performing the same treatment as in Example 1 except that polyvinyl alcohol was removed by hot water without performing water jet punching. The weight of the self-emulsifying polyurethane present in the surface layer 1/3 of the base material for leather-like sheet-like material was 89% by weight with respect to the weight of the self-emulsifying polyurethane in the whole sheet-like material.

  Further, the sheet-like material obtained by dyeing the obtained leather-like sheet-like substrate in the same manner as in Example 1 was very flexible, but the appearance was poor, and the pilling evaluation was also good. It was a bad result. When the obtained leather-like sheet-like base material was checked for intertwining of fibers with a microscope, the fiber bundles were intertwined, but at the single fiber level, they were not intertwined. This is considered to be a cause of poor evaluation.

[Comparative Example 4]
A leather-like sheet for comparison was carried out in the same manner as in Example 1 except that a self-emulsifying polyurethane aqueous dispersion VI added with sodium sulfate (Na ₂ SO ₄ ) was used to impart heat-sensitive gelation. A substrate was obtained. The weight of the self-emulsifying polyurethane present in the surface layer 1/3 of the base material for leather-like sheet was 67% by weight with respect to the weight of the self-emulsifying polyurethane of the whole base material.

  Moreover, although the appearance quality and the softness | flexibility of the sheet-like material obtained by dyeing | staining the obtained nap-like artificial leather-like base material similarly to Example 1 were favorable, the pilling evaluation was a bad result. .

Claims (6)

A base for a leather-like sheet-like material containing a self-emulsifying type polyurethane having a softening point of 70 ° C. or more and 150 ° C. or less in a nonwoven fabric in which ultrafine fibers having an average single fiber fineness of 0.001 dtex or more and 0.5 dtex or less are entangled It is a material, and single fibers of ultrafine fibers constituting the nonwoven fabric are intertwined, and the total polyurethane weight existing from the surface to the depth of 1/3 with respect to the thickness direction of the base material is A base material for leather-like sheet-like material, which is 70% by weight or more and 100% by weight or less of the total weight of polyurethane present. The base material for leather-like sheet material according to claim 1, wherein the fiber length of the ultrafine fibers constituting the nonwoven fabric is 25 mm or more and 90 mm or less. The base material for leather-like sheet material according to claim 1, wherein the self-emulsifying polyurethane is a polycarbonate-based polyurethane. 3. The leather-like sheet-like substrate according to claim 1, wherein the ultrafine fibers constituting the nonwoven fabric are polyester fibers. A leather-like sheet-like product obtained by dyeing the leather-like sheet-like substrate according to any one of claims 1 to 4. A method for producing a leather-like sheet-like substrate according to any one of claims 1 to 4, wherein ultrafine fibers having an average single fiber fineness of 0.001 dtex or more and 0.5 dtex or less are entangled by a high-pressure water stream. A method for producing a base material for leather-like sheet material, comprising impregnating a non-woven fabric with a self-emulsifying polyurethane having a softening point of 70 ° C or higher and 150 ° C or lower and drying.