JP2011006834A - Production method of leather-like sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leather-like sheet excellent in strength and having feeling closely resemble in natural leather.SOLUTION: There is provided a production method of a leather-like sheet which includes: a step for impregnating or coating on a fibrous substrate a heat-coagulable polyurethane resin emulsion (Q) containing a polyurethane resin (A), a plasticizer (B), a heat-sensitive coagulant (C) and an aqueous medium (D); a step of heat-coagulating the (Q) after the previous step; and a washing step; wherein, the weight ratio of (A) and (B), the solubility parameter of (B) and the heat-sensitive coagulation temperature of (Q) are specific values; (B) of ≥10 g is dissolved in 100 g water; the storage modulus of the dry film of (Q) and the storage modulus of the dry film of the polyurethane emulsion containing no (B) in the constituents of (Q) are specific values; and the residual ratio (X) of (B) after sheet production to that of the heat-sensitive coagulation step is ≤5 wt.%.

Description

  The present invention relates to a method for producing a leather-like sheet, and more particularly to a method for producing a leather-like sheet obtained using a heat-sensitive coagulable polyurethane resin emulsion.

Conventionally, in a method for producing a leather-like sheet, a method of applying a polyurethane resin as a binder to a fibrous base material has been performed. In order to obtain a leather-like sheet having an excellent texture such as natural leather, it is important that the polyurethane resin is uniformly applied to the fibrous base material. As a measure for this, it is effective to plasticize a polyurethane resin to improve the film-forming property, and a method for producing artificial leather using phosphate, adipate, sebacate or alkyl sulfonate as a plasticizer has been proposed ( For example, see Patent Document 1).
However, in the method proposed in Patent Document 1, since the plasticizer has low solubility in water and the plasticizer remains in the urethane resin applied to the leather-like sheet, the leather-like sheet having excellent strength. There is a problem that it is difficult to get.

JP 2005-248415 A

  This invention is made | formed in view of the said problem, and the subject of this invention is providing the leather-like sheet | seat which is excellent in intensity | strength and has the texture close | similar to natural leather.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have reached the present invention. That is, the present invention
A fibrous base material is impregnated or coated with a polyurethane resin emulsion (Q) having a heat-sensitive coagulation property comprising a polyurethane resin (A), a plasticizer (B), a heat-sensitive coagulant (C) and an aqueous medium (D). A method for producing a leather-like sheet comprising a step, a step of thermally coagulating (Q) after the step and a water washing step, and a method for producing a leather-like sheet satisfying all of the following (1) to (7): .
(1) The weight ratio [(A) :( B)] of (A) and (B) is 99: 1 to 40:60.
(2) 10 g or more of (B) is dissolved in 100 g of water at 25 ° C.
(3) The solubility parameter (SP value) of (B) is 9.2 to 12.5.
(4) The storage elastic modulus at 100 ° C. of the film obtained by drying (Q) is 0.01 to 0.1 MPa.
(5) The storage elastic modulus at 100 ° C. of the film obtained by drying the polyurethane resin emulsion (Q ′) not containing only (B) among the constituent components of (Q) is 0.5 to 10 MPa. .
(6) The thermal coagulation temperature of (Q) is 40 to 90 ° C.
(7) The weight (Wb2) of (B) per unit area in the manufactured leather-like sheet is divided by the weight (Wb1) of (B) per unit area of the fibrous base material after the thermal coagulation step. The residual rate (X) of (B) obtained is 5% by weight or less.

  By the method for producing a leather-like sheet of the present invention, a leather-like sheet having both the strength and texture of the sheet can be obtained.

  The polyurethane resin emulsion (Q) having heat-sensitive coagulation property in the present invention comprises a polyurethane resin (A), a plasticizer (B), a heat-sensitive coagulant (C), and an aqueous medium (D).

  The polyurethane resin (A) in the present invention is obtained by reacting the polymer polyol (a1) and polyisocyanate (a2) as essential raw materials. For the purpose of adjusting the mechanical strength of (A), a chain extender (a3) can be further used as a raw material. Further, for the purpose of improving the dispersion of (A), a hydrophilic group-containing active hydrogen compound (a4) can also be used as a raw material.

  Examples of the polymer polyol (a1) include polyether diol (a11), polyester diol (a12), and a mixture of two or more thereof.

  As the polyether diol (a11), a compound having a structure in which an alkylene oxide having 2 to 12 carbon atoms (hereinafter abbreviated as AO) is added to a bifunctional compound having 2 to 20 carbon atoms and two or more kinds thereof. Of the mixture.

  Examples of the active hydrogen atom-containing bifunctional compound having 2 to 20 carbon atoms include dihydric alcohols, dihydric phenols, and dicarboxylic acids.

Dihydric alcohols include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, bis (hydroxymethyl) cyclohexane and bis (hydroxyethyl) benzene. Etc.
Examples of the dihydric phenols include bisphenols such as bisphenol A, bisphenol F, and bisphenol S in addition to catechol and hydroquinone.
Examples of the dicarboxylic acid include aliphatic dicarboxylic acids such as succinic acid and adipic acid, and aromatic dicarboxylic acids such as phthalic acid and terephthalic acid.
Two or more kinds of the above-mentioned active hydrogen atom-containing compounds having 2 to 20 carbon atoms can be used.

Examples of AO having 2 to 12 carbon atoms to be added to an active hydrogen atom-containing bifunctional compound having 2 to 20 carbon atoms include ethylene oxide (hereinafter abbreviated as EO), 1,2- or 1,3-propylene oxide (hereinafter, Abbreviated PO), 1,2-, 2,3- or 1,3-butylene oxide, tetrahydrofuran (hereinafter abbreviated as THF), styrene oxide, α-olefin oxide, epichlorohydrin, and the like.
AO may be used singly or in combination of two or more, and in the case of combined use, block addition, random addition or a mixture of both may be used.
Among these AOs, preferred from the viewpoint of flexibility are EO alone, PO alone, THF alone, combined use of PO and EO, and combined use of PO and / or EO and THF, and particularly preferred is THF alone. .
Addition of AO to a C2-C20 active hydrogen atom-containing bifunctional compound can be carried out in the usual manner, and is carried out in the presence of no catalyst or a catalyst (an alkali catalyst, an amine catalyst or an acidic catalyst). .

  Specific examples of (a11) include polyethylene glycol, polypropylene glycol and polytetramethylene glycol, and polytetramethylene glycol is preferred.

The polyester diol (a12) is a condensation product obtained by reacting the dihydric alcohol and / or a polyether diol having a number average molecular weight (hereinafter abbreviated as Mn) of 1,000 or less with a dicarboxylic acid having 6 to 20 carbon atoms. A polyester diol (a121), a polycarbonate diol (a122) obtained by reacting the dihydric alcohol or a mixture thereof with a carbonic acid diester of a lower alcohol having 6 to 20 carbon atoms (such as methanol) and a lactone having 4 to 12 carbon atoms. Polylactone diol (a123) obtained by ring-opening polymerization is included.
In the present invention, (a1), (a3) and Mn of these raw materials are determined from the hydroxyl value, and the hydroxyl value can be measured by the method defined in JIS-K0070-1992 (potentiometric titration method).

  Examples of the polyether diol having an Mn of 1,000 or less include polytetramethylene ether glycol, polypropylene glycol, polyethylene glycol, and a mixture of two or more thereof.

Examples of the dicarboxylic acid having 2 to 20 carbon atoms include aliphatic dicarboxylic acids (such as succinic acid, adipic acid, azelaic acid and sebacic acid), aromatic dicarboxylic acids (such as terephthalic acid, isophthalic acid and phthalic acid), and these dicarboxylic acids. Examples thereof include ester-forming derivatives of acids [such as acid anhydrides and lower alkyl (carbon number 1 to 4) esters] and mixtures of two or more thereof.
Examples of the lactone having 4 to 12 carbon atoms include γ-butyrolactone, γ-valerolactone, ε-caprolactone, and a mixture of two or more thereof.

  The polyesterification reaction may be performed by a usual method, for example, a method of reacting (condensing) a low molecular diol and / or a polyether diol having an Mn of 1,000 or less with a dicarboxylic acid or an ester-forming derivative thereof, or an initiator (low molecular diol And / or a method of adding a lactone to a polyether diol having an Mn of 1,000 or less).

  (A121) includes polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentylene adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, polybutylene hexamethylene adipate diol and poly (polytetramethylene) Ethers) adipate-based condensed polyester diols such as adipate diol; azelate-based condensed polyester diols such as polyethylene azelate diol and polybutylene azelate diol; and sebacate-based condensed polyester diols such as polyethylene sebacate diol and polybutylene sebacate diol It is done.

As (a122), C4-10 linear alkylene carbonate diol (for example, polytetramethylene carbonate diol, polyhexamethylene carbonate diol and polynonamethylene polycarbonate diol) and alkylene having 4 to 4 carbon atoms. 10 branched alkylene carbonate diols (e.g., 2-methylbutanediol polycarbonate diol, 2-ethylbutanediol polycarbonate diol, neopentyl glycol polycarbonate diol, 2-methylpentanediol polycarbonate diol and 3-methylpentanediol Polycarbonate diol) and the like.
Examples of (a123) include polycaprolactone diol.

  Of (a1), from the viewpoint of the texture of the leather-like sheet and hydrolysis resistance, polyether diol (a11), polycarbonate diol (a122) and mixtures thereof are preferred, and polycarbonate diol (a122) is more preferred. Particularly preferred is at least one diol selected from the group consisting of tetramethylene glycol, hexamethylene glycol and 3-methylpentanediol and a low molecular carbonate compound (for example, a dialkyl carbonate having 1 to 6 carbon atoms in an alkyl group). Polycarbonate diol produced by condensation with a dealcoholization reaction, and most preferred is polytetramethylene carbonate diol, polyhexamethylene carbonate diol, 3-methylpentanediol. Which is a polycarbonate diol.

  Mn in (a1) is usually 400 to 5,000, preferably 500 to 5,000, and more preferably 1,000 to 3,000, from the viewpoint of the flexibility of the resin.

  As the polyisocyanate (a2), those conventionally used for polyurethane production can be used. (A2) is carbon number (excluding carbon in NCO group, the same shall apply hereinafter) 6-20 aromatic diisocyanate, C2-C18 aliphatic diisocyanate, C4-C15 alicyclic diisocyanate, carbon number 8-15 araliphatic diisocyanates, modified products of these diisocyanates (carbodiimide-modified products, urethane-modified products, uretdione-modified products, etc.) and mixtures of two or more of these.

  Examples of the aromatic diisocyanate having 6 to 20 carbon atoms include 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 2,4′- or 4,4′-diphenylmethane diisocyanate. 4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-diisocyanatobiphenyl, 3,3′-dimethyl-4,4′-diisocyanatodiphenylmethane and 1,5-naphthy Range isocyanate etc. are mentioned.

  Examples of the aliphatic diisocyanate having 2 to 18 carbon atoms include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, and 2,6-diisocyanatomethylcapro. And bis (2-isocyanatoethyl) carbonate and 2-isocyanatoethyl-2,6-diisocyanatohexanoate.

  Examples of the alicyclic diisocyanate having 4 to 15 carbon atoms include isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis (2-isocyanatoethyl) -4-cyclohexylene-1, Examples include 2-dicarboxylate and 2,5- or 2,6-norbornane diisocyanate.

  Examples of the araliphatic diisocyanate having 8 to 15 carbon atoms include m- or p-xylylene diisocyanate and α, α, α ′, α′-tetramethylxylylene diisocyanate.

  Among (a2), from the viewpoint of the flexibility of the resin, alicyclic diisocyanates having 4 to 15 carbon atoms are preferred, and isophorone diisocyanate and 4,4'-dicyclohexylmethane diisocyanate are more preferred.

Chain extenders (a3) include diamines having 2 to 10 carbon atoms (for example, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine and toluenediamine); polyamines (for example, diethylenetriamine and triethylenetetramine); hydrazine or its derivatives ( Dibasic acid dihydrazides such as adipic acid dihydrazide); polyhydric alcohols having 2 to 20 carbon atoms [the aforementioned dihydric alcohols, trihydric alcohols (eg glycerin and trimethylolpropane) and EO and / or of these polyhydric alcohols] PO low molar adduct (Mn less than 500)] and the like.
Among these, a dihydric alcohol having 2 to 6 carbon atoms is preferable from the viewpoint of adjusting the resin strength.

  As the hydrophilic group-containing active hydrogen compound (a4), a C6-C24 carboxyl group-containing polyol (a41) [dialkylol alkanoic acid such as 2,2-dimethylolpropionic acid (hereinafter abbreviated as DMPA), 2 , 2-dimethylolbutanoic acid, 2,2-dimethylolheptanoic acid and 2,2-dimethyloloctanoic acid}], a C2-C10 sulfo group-containing polyol (a42) [sulfonic acid diol {3- (2 , 3-dihydroxypropoxy) -1-propanesulfonic acid and the like} and sulfamic acid diol {N, N-bis (2-hydroxyalkyl) sulfamic acid and its AO adduct (added mole number 2 to 20)}] and these Examples include salts.

When (a4) is a salt, the salt includes a neutralized salt of (a41) or (a42) and a neutralizing agent (a5).
Examples of (a5) include ammonia, amines having 1 to 12 carbon atoms [primary monoamines (eg, methylamine, ethylamine, propylamine and octylamine), secondary monoamines (dimethylamine, diethylamine and dibutylmine), tertiary monoamines ( Aliphatic tertiary monoamines such as trimethylamine, triethylamine, triethanolamine, N-methyldiethanolamine and N, N-dimethylethanolamine; heterocyclic tertiary monoamines such as N-methylpiperidine and N-methylmorpholine; benzyldimethylamine; α-methylbenzyldimethylamine; and aromatic ring-containing tertiary monoamines such as N-dimethylaniline)], alkali metal hydroxides (lithium hydroxide, potassium hydroxide, sodium hydroxide, etc.) and two or more of these Use and the like. Of these, amines having 1 to 12 carbon atoms are preferable from the viewpoint of emulsifying properties, aliphatic tertiary monoamines having 1 to 12 carbon atoms are more preferable, and triethylamine is particularly preferable.

  The amount of the neutralizing agent (a5) used does not particularly affect the performance of the leather-like sheet, but is usually 20 to 200 mol%, preferably 30 to 150 mol, based on the total of carboxyl groups and sulfo groups. %. When the amount of (a5) used is 30 mol% or more, the storage stability of the polyurethane resin emulsion is further improved. Moreover, in the case of 150 mol% or less, the viscosity of a polyurethane resin emulsion can be further reduced, which is preferable from the viewpoint of handling.

  Addition of the neutralizing agent (a5) may be either a method of adding to the urethane prepolymer before the dispersion of (A) or a method of adding after the dispersion.

  In the urethanization reaction for obtaining (A) in this invention, in order to accelerate reaction, you may use the catalyst used for normal urethanation reaction as needed. Examples of the catalyst include amine catalysts such as triethylamine, N-ethylmorpholine, and triethylenediamine, and cycloamidines described in US Pat. No. 4,524,104 [1,8-diaza-bicyclo (5,4,0) undecene-7. (San Apro Co., Ltd., DBU), etc.], tin-based catalysts such as dibutyltin dilaurate, dioctyltin dilaurate and tin octylate, and titanium-based catalysts such as tetrabutyl titanate.

  Mn of the polyurethane resin (A) can be measured by gel permeation chromatography (hereinafter abbreviated as GPC). When (A) is a non-crosslinked type (thermoplastic), usually 10,000 to 200, 000 or more, preferably 30,000 to 150,000, especially 50,000 to 100,000. When (A) is a crosslinked type, it may be Mn higher than the above range or high Mn that cannot be measured by GPC.

The plasticizer (B) in the present invention contributes to improving the film-forming property of the polyurethane resin emulsion (Q) until the heat-sensitive coagulation step in the production process of the leather-like sheet, and the subsequent steps (for example, ultrafine fiber formation step, It is extracted with a water-soluble treatment solution in the dyeing step and the water washing step), and the amount thereof is reduced, thereby expressing the strength of the polyurethane resin and improving the strength of the leather-like sheet to be produced.
Accordingly, the plasticizer (B) needs to be water-soluble, that is, dissolve 10 g or more with respect to 100 g of water at 25 ° C., preferably 15 g or more, more preferably 20 g or more.
The solubility in water can be measured by diluting the plasticizer (B) with 100 g of water at 25 ° C. and confirming that it is uniform visually.

Examples of the plasticizer (B) include the following (B1) to (B7) having a solubility of 10 g or more with respect to 100 g of water at 25 ° C.
1 to 6-valent aliphatic alcohols having 1 to 10 carbon atoms (B1): monovalent alcohols such as methanol, ethanol and 1-propanol, ethylene glycol, propylene glycol, glycerin, diglycerin, tetraglycerin, trimethylolpropane, Divalent to 6-valent alcohols such as ditrimethylolpropane, neopentyl alcohol, pentaerythritol, dipentaerythritol, sorbitan, sorbitol, sucrose and glucose.
C2-C10 aliphatic mono-, di- or triamine (B2): ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, diethylenetriamine and the like.
C2-C10 ether (B3): Tetrahydrofuran, dioxane, diethyl ether, monoethyl ether of diethylene glycol, and the like.
C2-C6 polycarboxylic acid (salt) (B4): oxalic acid, succinic acid, fumaric acid, maleic acid, gluconic acid and alkali metal salts or alkaline earth metal salts thereof.
C8-24 sulfonate (B5); sodium dodecylbenzenesulfonate and the like.
Quaternary ammonium salt having 4 to 40 carbon atoms (B6): stearyltrimethylammonium chloride, behenyltrimethylammonium chloride, distearyldimethylammonium chloride, ethyl lanolin sulfate fatty acid aminopropylethyldimethylammonium, etc.]; and amine salt type [diethylamino stearate Ethylamide lactate, dilaurylamine hydrochloride, oleylamine lactate and the like.
(B1), (B2) or a C2-C4 monovalent alcohol adduct (Mn150-1500) (B7): AO20 of lauryl alcohol, cetyl alcohol, ethylene glycol or propylene glycol Mole adduct etc.

Examples of the monohydric alcohol having 7 to 20 carbon atoms include heptanol, octanol, lauryl alcohol, cetyl alcohol, and octadecyl alcohol.
In addition, examples of the AO having 2 to 4 carbon atoms include those having 2 to 4 carbon atoms in the AO having 2 to 12 carbon atoms. Of these AOs, EO, PO, and a combination thereof are preferred from the viewpoint of easily exhibiting water solubility. In the case of combined use, the amount of PO is preferably 30 mol% or less, and the bonding mode may be random, block, or a combination thereof.

Among these, (B7) is preferable from the viewpoint of water solubility and plasticity, more preferable is an AO adduct having 2 to 4 carbon atoms of (B1), and particularly preferable is polyethylene having Mn of 200 to 1,000. Polypropylene glycol having glycol and Mn of 200 to 1,000.
A plasticizer (B) may be used independently and may use 2 or more types together.

  In the present invention, one or two or more plasticizers having a solubility of 10 g or more with respect to 100 g of water at 25 ° C. are used as the plasticizer (B). A plasticizer having a solubility in 100 g of water of less than 10 g can be used in combination. In this case, the solubility of the plasticizer mixture in water needs to be 10 g or more at 25 ° C.

Moreover, the solubility parameter (hereinafter abbreviated as SP value) of the plasticizer (B) is 9.2 to 12.5 from the viewpoint of the solubility in water of (B), the plasticizing effect, and the sheet strength. Is required, preferably 9.5 to 12.0, particularly preferably 10.0 to 11.5.
In addition, SP value in this invention is Polymer Engineering and Science, February, 1974, Vol. 14, no. 2, 147 to 154, which is a value calculated by the Fedors method.
SP value = (ΔH / V) ^1/2
In the formula, ΔH represents molar heat of vaporization (cal), and V represents molar volume (cm ³ ).
In addition, when using 2 or more types of plasticizers, let the value calculated | required by the weight average from the usage-amount of each plasticizer and SP value be SP value in this invention.

  The plasticizer (B) can also be used as an emulsifier for dispersing in the aqueous medium (D) when the polyurethane resin (A) does not contain the hydrophilic group-containing active hydrogen compound (a4).

  In order for the polyurethane resin emulsion (Q) in the present invention to have heat-sensitive coagulation properties, it is necessary to contain a heat-sensitive coagulant (C).

  Examples of the heat-sensitive coagulant (C) include organic acid salt (C1), inorganic salt (C2), polyvinyl methyl ether, silicone polyether copolymer and polysiloxane.

  Examples of the organic acid salt (C1) include neutralized salts of carboxylic acids having 1 to 20 carbon atoms (such as formic acid, acetic acid, propionic acid and malic acid) and sulfamic acid and the neutralizing agent (a5).

  Examples of the inorganic salt (C2) include an alkali metal salt (C21), an alkaline earth metal salt (C22), and an ammonium salt (C23).

  Examples of the alkali metal salt (C21) include alkali metal carbonate [sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate and lithium carbonate], alkali metal sulfate [sodium sulfate and potassium sulfate], alkali metal nitrate [sodium nitrate]. And potassium nitrate], alkali metal phosphates [sodium phosphate, sodium hydrogen phosphate and potassium phosphate], alkali metal sulfites [sodium sulfite, sodium hydrogen sulfite and potassium sulfite] and alkali metal halogens (chlorine, bromine, iodine or Fluorine) compounds [sodium chloride, potassium chloride, sodium bromide, potassium iodide and potassium fluoride] and the like.

  Alkaline earth metal salts (C22) include alkaline earth metal carbonates (such as calcium carbonate and magnesium carbonate), alkaline earth metal sulfates (such as calcium sulfate and magnesium sulfate), alkaline earth metal nitrates (calcium nitrate and Magnesium nitrate, etc.), alkaline earth metal phosphates (eg calcium hydrogen phosphate and magnesium hydrogen phosphate), alkaline earth metal sulfites (eg calcium sulfite and magnesium sulfite) and alkaline earth metal halogens (chlorine, bromine, Iodine or fluorine) [calcium chloride, magnesium chloride, calcium bromide, calcium iodide and magnesium fluoride] and the like.

Examples of the ammonium salt (C23) include ammonium halides (such as ammonium chloride and ammonium bromide).
Of these, organic acids (C1) and inorganic salts (C2) are preferred from the viewpoint of heat-sensitive coagulation, and alkaline earth metal salts (C22) are more preferred.

Examples of the aqueous medium (D) in the present invention include water alone or a mixture of water and a hydrophilic solvent.
Examples of the hydrophilic solvent include acetone, methyl ethyl ketone, tetrahydrofuran, and N, N-dimethylformamide.
Although there is no restriction | limiting in particular as addition amount (weight%) in the case of mixing a hydrophilic solvent with water, 1-50 weight% is preferable on the basis of the weight of water.

Examples of the method for producing the polyurethane resin emulsion (Q) in the present invention include the following two methods.
(1) A prepolymer of a terminal isocyanate group (hereinafter abbreviated as a terminal NCO group urethane prepolymer) is prepared by reacting (a1), (a2) and, if necessary, (a3), (a4) and (a5) in advance. In the presence of a plasticizer (B), a heat-sensitive coagulant (C), and if necessary, a chain extender (a3), etc., it is dispersed in an aqueous medium (D). How to do.
(2) (a1), (a2) and, if necessary, (a3), (a4) and (a5) are reacted in advance to produce a terminal hydroxyl group polyurethane resin, and the plasticizer (B), heat-sensitive coagulant A method of dispersing in an aqueous medium (D) in the presence of (C).
Among these, the method (1) is preferable from the viewpoint of the texture of the leather sheet.

The terminal NCO group urethane prepolymer in the method (1) is used in the presence of a hydrophilic organic solvent (acetone, methyl ethyl ketone, tetrahydrofuran, N, N-dimethylformamide, etc.) that does not contain an active hydrogen-containing group in the molecule In the presence, the (NCO / hydroxyl) equivalent ratio of the polymer polyol (a1) and the polyisocyanate (a2) and, if necessary, the active hydrogen component comprising the chain extender (a3) and the hydrophilic group-containing active hydrogen compound (a4) However, usually after reaction at 20 ° C. to 150 ° C., preferably 60 ° C. to 110 ° C., by the one-shot method or multistage method in the range of 1.05 to 2.0, preferably 1.1 to 1.6. If necessary, it is obtained by neutralization with (a5).
The polyurethane resin having a terminal hydroxyl group in the method (2) is prepared in the presence or absence of an organic solvent containing no active hydrogen-containing group in the molecule, and (a1), (a2) and, if necessary, (a3) and The active hydrogen component consisting of (a4) is reacted with the one-shot method or the multistage method in the range where the (NCO / OH) equivalent ratio is 0.5 to 0.99 to obtain a urethane polymer having a terminal hydroxyl group. If necessary, it can be obtained by neutralization with (a5).

  The plasticizer (B) may be added at the time of producing the emulsion, or may be added and blended after the production of the emulsion, but is preferably added at the time of producing the emulsion from the viewpoint of the plasticizing effect.

In order to improve the dispersion stability of the polyurethane resin emulsion (Q), a small amount of a surfactant can be used in the dispersion steps (1) and (2).
The surfactant is not particularly limited, and includes 40-carbon aliphatic alcohol EO adduct, phenol EO adduct, nonylphenol EO adduct and amine EO adduct having 8 to 22 carbon atoms. Nonionic surfactants having a cloud point of from ℃ to 180 ℃ are exemplified.
From the viewpoint of the water resistance of the leather-like sheet, the amount of the surfactant added is usually less than 2% by weight, preferably less than 1% by weight, based on (A).

  In this invention, the apparatus at the time of manufacturing a polyurethane resin emulsion (Q) is not specifically limited, For example, the emulsifier of the following system is mentioned: (1) Vertical stirring system, (2) Rotor-stator type System [e.g. "Ebara Milder" (manufactured by Ebara Seisakusho)], (3) Line mill system [e.g. line flow mixer], (4) Static tube mixing type [e.g. static mixer], (5) Vibration type [e.g. (6) Ultrasonic impact type [for example, ultrasonic homogenizer], (7) High pressure impact type [for example, Gaurin homogenizer (Gaurin)], (8) Membrane emulsification type [for example, membrane emulsification] Module] and (9) Centrifugal thin film contact type [for example, film mix]. Among these, (1), (2) and (9) are preferable from the viewpoint of shearing force.

The content of the polyurethane resin (A) in the polyurethane resin emulsion (Q) is usually 3 to 40% by weight, preferably 3 to 20% by weight, based on the weight of (Q), from the viewpoint of production cost.
The weight ratio of (A) to (B) is usually 99: 1 to 40:60, preferably 95: 5 to 80:20, and more preferably 90:10 to 85:15.
The content of the heat-sensitive coagulant (C) in the polyurethane resin emulsion (Q) is usually 1 to 5% by weight, preferably 1 to 3% by weight, based on the weight of (Q), from the viewpoint of the coagulability of (Q). %.
The content of (D) in the polyurethane resin emulsion (Q) is usually 50 to 90% by weight, preferably 70 to 85% by weight, based on the weight of (Q), from the viewpoint of the impregnation efficiency of (Q). .

  In the present invention (Q), if necessary, a colorant such as titanium oxide, an ultraviolet absorber (benzophenone-based or benzotriazole-based) or an antioxidant [4,4′-butylidene-bis (3-methyl-6-1). -Hindered phenols such as butylphenol; organic phosphites such as triphenyl phosphite and trichloroethyl phosphite], etc., preservatives, cross-linking agents (polyepoxy compounds and polyisocyanate compounds, etc.), inorganic fillers (Calcium carbonate, etc.) can be added. The total amount of these additives is preferably 5 parts by weight or less based on the weight of (Q). More preferably, it is 0.1 to 3 parts by weight.

In the present invention, in order to improve the film-forming property and sheet strength of the urethane resin emulsion (Q) in the heat-sensitive coagulation step, the storage modulus (MPa) of the film obtained by drying (Q) at 100 ° C. ) Must be 0.01 to 0.1, preferably 0.02 to 0.09, and particularly preferably 0.03 to 0.08.
The storage modulus in the present invention is the film obtained by placing (Q) in a polypropylene tray so that the film thickness after drying is 200 μm, drying at 25 ° C. for 24 hours, and further drying at 120 ° C. for 2 hours. , Storage elastic modulus measuring device [Rheogel E4000 {manufactured by UBM Co., Ltd.}] was used to measure the storage elastic modulus at 100 ° C. at a frequency of 11 Hz.

In the present invention, the storage elastic modulus (MPa) at 100 ° C. of the film obtained by drying the polyurethane resin emulsion (Q ′) not containing only (B) among the components (Q) is: From the viewpoint of sheet strength, it is necessary to be 0.5 to 10, preferably 0.55 to 8, particularly preferably 0.6 to 5. When the storage elastic modulus is 0.5 or less, the strength of the obtained leather sheet is not preferable. Further, if the storage elastic modulus is 10 or more, a uniform sheet cannot be obtained, and the texture is lowered.
The measurement conditions for the storage elastic modulus of (Q ′) are the same as described above.

The thermal coagulation temperature (Q) in the present invention is usually 40 to 90 ° C, preferably 50 to 70 ° C. When it is less than 40 ° C., the storage stability of (Q) is deteriorated, and when it exceeds 90 ° C., solidification is slow and migration of the polyurethane resin occurs, so that the texture of the leather sheet is lowered.
The thermal solidification temperature of (Q) can be measured by heating (Q) and reading the temperature at which the solidification flow stops.

  The volume average particle diameter of (Q) is preferably 0.01 μm to 1 μm, more preferably 0.02 μm to 0.5 μm, from the viewpoint of dispersion stability. The average particle diameter can be measured using an ELS-800 electrophoretic light scattering photometer manufactured by Otsuka Electronics Co., Ltd.

As the fibrous base material used in the production of the leather-like sheet of the present invention, a nonwoven fabric or a woven fabric conventionally used in the production of a leather-like sheet can be used.
The nonwoven fabric may be one in which a woven fabric or the like is laminated on the inside or the surface for the purpose of reinforcement or the like.
The fibers constituting the fibrous base material may be either natural fibers or chemical fibers.
Natural fibers include cotton, wool, silk and asbestos, and chemical fibers include regenerated fibers such as rayon and tencel, semi-synthetic fibers such as acetate and triacetate, and synthetic fibers such as polyamide, polyester, polyolefin and acrylic. It is also possible to use fibers that are mixed and used. Furthermore, the fibers constituting the fibrous base material may be ultrafine fiber generating fibers, such as sea-island type composite fibers.

  The method for producing a leather-like sheet of the present invention has a step of impregnating or applying (Q) on a fibrous base material, a heat-sensitive coagulation step, and a water washing step as essential steps. A process used for sheet manufacture can be provided. For example, a leather-like sheet can be produced through an impregnation or coating process, a heat-sensitive coagulation process, an ultrafine fiber forming process, a dyeing process, and a water washing process performed after these processes.

Any impregnation or application method may be used as long as it is a commonly performed method.
For example, a method of impregnating (Q) into a fibrous base material and squeezing with a mangle or the like to prepare a pickup, and other methods such as knife coating, air knife coating, roll coating and spray coating can be mentioned.

Examples of the heat-sensitive coagulation method (Q) applied to the fibrous base material include (1) a method of heat-sensitive coagulation by spraying heated steam and then heat-drying or air-drying using a drying device, and (2) a drying device. Examples thereof include a method of introducing the solution as it is, solidifying by heating and drying.
Among the above, the method (1) is preferable.

  The temperature of the atmosphere for thermally coagulating (Q) imparted to the fibrous base material is preferably 40 to 180 ° C., from the viewpoint of quickly completing the coagulation bath stability and coagulation of the polyurethane resin emulsion. Preferably it is 60-150 degreeC, Most preferably, it is 70-120 degreeC. The time for heat-sensitive coagulation varies depending on the temperature, but is usually 0.1 minutes to 30 minutes, preferably 0.5 minutes to 20 minutes.

  The drying temperature after solidification is usually 100 to 200 ° C, preferably 120 to 180 ° C, and the time is usually 1 to 60 minutes, preferably 2 to 30 minutes.

  In the case of using a substrate made of ultrafine fiber-generating fibers as the fibrous substrate, it is possible to form ultrafine fibers by providing a step of removing sea components using an aqueous alkali solution or an organic solvent following the heat-sensitive coagulation step.

In the method for producing a leather-like sheet of the present invention, a dedicated water washing step may be provided in order to remove the plasticizer (B). However, after the heat-sensitive coagulation step, an ultrafine fiberization step, a dyeing step, and after these steps It can also be extracted and removed in the water washing step that is carried out.
The temperature and time for removing (B) in the water washing step or the like may be the same as the conditions in the ultrafine fiber forming step, the dyeing step, and the water washing step performed after these steps, ) And the amount used can be adjusted as appropriate.

  The residual rate (X) of (B) is the weight of (B) per unit area in the manufactured leather-like sheet (Wb2), the weight of (B) per unit area of the leather-like sheet after the thermal coagulation step ( A value obtained by dividing (dividing) by Wb1) as a percentage. The residual ratio (X) of (B) is usually 5% by weight or less, more preferably 3% by weight or less, and particularly preferably 1% by weight or less from the viewpoint of sheet strength.

The residual rate (X) of (B) can be determined by the following method.
(1) (Wb1) is obtained by the following method.
(Wb1) = Wq × Cb / S ′
Wq: Weight (g) of (Q) impregnated in the fiber base material
Cb: concentration of (B) in (Q) (%)
S: Area of leather-like sheet (cm ² )
(2) (Wb2) is obtained by the following method.
The manufactured leather-like sheet is immersed in 100 times the amount of water with respect to the sheet weight (Wa) and allowed to stand for 24 hours. Subsequently, the leather-like sheet is dried at 120 ° C. for 20 minutes, and the sheet weight (Wa ′) is measured. A value obtained by dividing the difference between (Wa) and (Wa ′) by the area of the manufactured leather-like sheet is defined as (Wb2). The calculation formula is as follows.
(Wb2) = (Wa−Wa ′) / S ′
Wa: Weight of manufactured sheet (g)
Wa ′: sheet weight (g) obtained by the above extraction operation
S ': Area of the leather-like sheet (cm ² )
(3) From the above (Wb1) and (Wb2), (X) is obtained using the following equation.
(X) = (Wb2) / (Wb1) × 100.

  The adhesion weight of the polyurethane resin (A) to the fibrous base material is preferably 3 to 150 parts by weight, more preferably 10 to 100 parts by weight, particularly preferably from 100 parts by weight of the fibrous base material from the viewpoint of sheet strength. 20 to 50 parts by weight.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to this. In the following, “parts” indicates parts by weight.

<Manufacture of polyurethane resin emulsion>
Production Example 1
A pressure-resistant reaction vessel equipped with a thermometer and a stirrer was charged with 537 parts of polytetramethylene glycol of Mn2,000, 16.7 parts of α, α-dimethylolpropionic acid (DMPA), 143 parts of isophorone diisocyanate and 300 parts of acetone and reacted. After replacing the system with nitrogen gas, the mixture was reacted at 90 ° C. for 10 hours with stirring to obtain an acetone solution of a terminal NCO group urethane prepolymer. The system was cooled to 40 ° C. and 15.1 parts of triethylamine was added. Next, 2.0 parts of hexadecyl alcohol EO 14 mol adduct as a plasticizer and 174 parts of polyethylene glycol of Mn = 600 dissolved in 335 parts of water were added and emulsified by stirring for 1 minute with a homomixer. A solution obtained by dissolving 6.4 parts of ethylenediamine in 554 parts of water was added to cause a chain extension reaction, then acetone was distilled off under reduced pressure, and the concentration was adjusted with water to obtain a urethane resin (A) concentration of 40% by weight, A polyurethane resin emulsion (q-1) having an average dispersed particle size of 0.2 μm was obtained.

Production Example 2
A polyurethane resin emulsion (q-2) was obtained in the same manner as in Production Example 1 except that the polytetramethylene glycol of Mn2,000 was replaced with the polyhexamethylene carbonate diol of Mn2,000.

Production Example 3
A polyurethane resin emulsion (q-3) was obtained in the same manner as in Production Example 1 except that the polytetramethylene glycol of Mn 2,000 was replaced with a condensed polyester diol of 1,4-butanediol and adipic acid of Mn 2,000. .

Production Example 4
Polyurethane resin emulsion-4 was obtained in the same manner as in Production Example 1 except that the amount of polyethylene glycol charged was changed to 19.8 parts and the amount of water dissolving ethylenediamine was changed to 708 parts of water. Except for the above, a polyurethane resin emulsion (q-4) was obtained in the same manner as in Production Example 1.

Production Example 5
Production Example 1 except that the amount of polyethylene glycol charged is changed to 893 parts, the amount of water dissolving ethylenediamine is changed to 88 parts, and the concentration of the polyurethane resin (A) is adjusted to 35% by weight with water. In the same manner as above, a polyurethane resin emulsion (q-5) was obtained.

Production Example 6
A polyurethane resin emulsion (q-6) was obtained in the same manner as in Production Example 1, except that 269 parts of 537 parts of polytetramethylene glycol of Mn 2,000 were replaced with polyhexamethylene carbonate diol of Mn 2,000.

Production Example 7
A pressure resistant reactor equipped with a thermometer and a stirrer was charged with 537 parts of polyhexamethylene carbonate diol of Mn2,000, 16.7 parts of α, α-dimethylolpropionic acid (DMPA), 143 parts of isophorone diisocyanate and 300 parts of acetone, After replacing the reaction system with nitrogen gas, the reaction was carried out at 90 ° C. for 10 hours with stirring to obtain an acetone solution of a terminal NCO group urethane prepolymer. The system was cooled to 40 ° C. and 15.1 parts of triethylamine was added. Next, after 335 parts of water was added to the acetone solution and emulsified by stirring for 1 minute with a homomixer, 6.4 parts of ethylenediamine was dissolved in 554 parts of water to cause a chain extension reaction, and then acetone was added under reduced pressure. Distilled off. A polyurethane resin having a polyurethane resin (A) concentration of 40% by weight and an average dispersed particle size of 0.4 μm was added to the obtained polyurethane resin emulsion by adding 176 parts of polyethylene glycol of Mn = 600 as a plasticizer and adjusting the concentration with water. An emulsion (q-7) was obtained.

Comparative production example 1
Polyurethane resin emulsion (y) in the same manner as in Production Example 1 except that 2.0 parts of EO 14 mol adduct of hexadecyl alcohol and 174 parts of polyethylene glycol having Mn = 600 were dissolved in 335 parts of water were replaced with 511 parts of water. -1) was obtained.

Comparative production example 2
Except for changing the amount of polyethylene glycol charged to 1305 parts, the amount of water for dissolving ethylenediamine to 14 parts, and adjusting the concentration of the polyurethane resin (A) to 30% by weight with water. A polyurethane resin emulsion (y-2) was obtained in the same manner as in Production Example 1.

Comparative production example 3
EO14 mol adduct of hexadecyl alcohol and polyethylene glycol are dissolved in “DIBA” [manufactured by Daihachi Chemical Industry Co., Ltd., diisobutyl adipate at 25 ° C. in 0.5 g per 100 g of water. ] A polyurethane resin emulsion (y-3) was obtained in the same manner as in Production Example 1, except that

Comparative production example 4
A polyurethane resin emulsion (y-4) was obtained in the same manner as in Production Example 1 except that polyethylene glycol was replaced with polypropylene glycol with Mn = 2,000.

Comparative Production Example 5
A polyurethane resin emulsion (y-5) was obtained in the same manner as in Production Example 1 except that polyethylene glycol was replaced with an 2.7 mol adduct of glycerin.

<Manufacture of non-woven fabric>
A laminated sheet is made from polyethylene terephthalate short fibers, and this sheet is needle-punched so that the number of shots is 280 pieces / cm ² to obtain a nonwoven fabric having a weight of 380 g / m ² and an apparent density of 0.18 g / cm ^2. It was.

Example 1
To 100 parts of the polyurethane resin emulsion (q-1), 60 parts of a 10% by weight aqueous solution of calcium chloride as a heat-sensitive coagulant are added so that the concentration of the heat-sensitive coagulant in the polyurethane resin emulsion is 3% by weight. Furthermore, the polyurethane resin emulsion (Q-1) was obtained by adjusting by adding water so that the polyurethane resin concentration was 20% by weight. (Q-1) is impregnated into the nonwoven fabric cut to 10 cm × 20 cm, and after squeezing with mangle so that the adhesion rate of the urethane resin is 50% by weight, a part of the sheet is made 10 cm × 10 cm. The weight (Wq) of (Q-1) impregnated was measured from the sheet weight measured by cutting and the weight per 10 cm ^{2 of} the nonwoven fabric measured in advance. The remaining sheet was heated in 100 ° C. saturated steam for 5 minutes to heat-coagulate, dried in a hot air dryer at 120 ° C. for 20 minutes, cooled to room temperature, and the sheet weight (Wq1 ′) was measured. The obtained leather-like sheet is placed in a container containing 100 times the amount of the dyeing solution relative to (Wq1 ′) and stirred with a stirrer equipped with three blades [dye: Sakai Obex Co., Ltd. Miketon Poly. Yellow GSL, temperature: 60 ° C., time: 5 hours], and put the obtained leather-like sheet into a container containing 100 times the amount of water (Wq1 ′) at 25 ° C. for 20 minutes, 3 sheets After washing with water by stirring with a stirrer equipped with blades, it was dried at 120 ° C. for 20 minutes to obtain a leather-like sheet by the production method of the present invention.

Examples 2-7
Except for replacing the polyurethane resin emulsion (q-1) with the polyurethane resin emulsions (q-2) to (q-7), in the same manner as in Example 1, the polyurethane resin emulsions (Q-2) of Examples 2 to 7 (Q-7) and a leather-like sheet were obtained.

Comparative Examples 1-3
The polyurethane resin emulsions (Y-1) to Comparative Examples 1 to 3 are the same as in Example 1 except that the polyurethane resin emulsion (q-1) is replaced with the polyurethane resin emulsions (y-1) to (y-3). (Y-3) and a leather-like sheet were obtained.

Comparative Example 4
A polyurethane resin emulsion (Y-4) and a leather-like sheet were obtained in the same manner as in Example 1 except that 60 parts of a 10% by weight aqueous solution of calcium chloride were not added.

Comparative Examples 5-6
Except that the polyurethane resin emulsion (q-1) is replaced with the polyurethane resin emulsions (y-4) to (y-5), the polyurethane resin emulsions (Y-5) to (Y-5) to ( Y-6) and a leather-like sheet were obtained.

  Composition of polyurethane resin emulsions (Q-1) to (Q-7) and (Y-1) to (Y-6) in Examples 1 to 7 and Comparative Examples 1 to 6, thermal coagulation temperature, basis weight of polyurethane resin Tables 1 and 2 show the storage elastic modulus of the dry film of the polyurethane resin emulsion, the residual rate of the plasticizer, the shape change rate and the texture of the leather-like sheet measured or evaluated by the following test methods.

[Storage modulus-1]
Film thickness after drying polyurethane resin emulsions (Q-1) to (Q-7) and (Y-1) to (Y-6) of Examples 1 to 7 and Comparative Examples 1 to 6 on polypropylene trays is 200 μm. For a film having a thickness of 200 μm obtained by drying at 25 ° C. for 24 hours and further drying at 120 ° C. for 2 hours, a storage elastic modulus measuring device, Rheogel E4000 [manufactured by UBM Co., Ltd.] The storage modulus at 100 ° C. was measured at a frequency of 11 Hz.

[Storage modulus-2]
Among the constituents of the polyurethane resin emulsions (Q-1) to (Q-7) and (Y-1) to (Y-6) of Production Examples 1 to 7 and Comparative Production Examples 1 to 6, a plasticizer (B A polyurethane resin emulsion containing only That is, the polyurethane resin emulsion which does not use a plasticizer in a manufacture example and a comparative manufacture example is manufactured, and a heat-sensitive coagulant and water are added similarly to Examples 1-7 and Comparative Examples 1-6, and a polyurethane resin emulsion is manufactured. did. However, in the case corresponding to Comparative Example 4, only water was added without adding the heat-sensitive coagulant. Subsequently, the storage elastic modulus at 100 ° C. was measured using the polyurethane resin emulsion in the same manner as the measuring method of the storage elastic modulus-1.

[Residual rate of plasticizer]
(1) The weight (Wb1) of the plasticizer per unit area of the leather-like sheet after the heat-sensitive coagulation step was determined by the following method.
(Wb1) = Wq × Cb / S ′
Wq: Weight (g) of (Q) impregnated in the fiber base material
Cb: concentration of (B) in (Q) (%)
S: Area of leather-like sheet (cm ² )
(2) The weight of plasticizer per unit area (Wb2) in the produced leather-like sheet was determined by the following method.
The manufactured leather-like sheet was soaked in 100 times the amount of water with respect to the sheet weight (Wa) and allowed to stand for 24 hours. Subsequently, the leather-like sheet was dried at 120 ° C. for 20 minutes, and the sheet weight (Wa ′) was measured. A value obtained by dividing the difference between (Wa) and (Wa ′) by the area of the manufactured leather-like sheet was defined as (Wb2). The calculation formula is as follows.
(Wb2) = (Wa−Wa ′) / S ′
Wa: Weight of manufactured sheet (g)
Wa ′: sheet weight (g) obtained by the above extraction operation
S ': Area of the leather-like sheet (cm ² )
(3) The residual ratio (X) of the plasticizer was determined using the following equation from (Wb1) and (Wb2).
(X) = (Wb2) / (Wb1) × 100.

[Strength of leather-like sheet (shape change rate)]
The strength of the manufactured leather-like sheet was evaluated by hitting the sheet with water using a liquid dyeing machine. That is, if the polyurethane resin contained in the manufactured sheet is insufficient in film-forming property or if the residual amount of plasticizer is large, the polyurethane resin will fall off when it is pulled or pulled in a liquid dyeing machine. The sheet shape change rate becomes high. The specific evaluation method of the shape change rate of the manufactured leather-like sheet is as follows.
The leather-like sheets obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were cut into dimensions of 10 cm in length and 10 cm in width (thickness was 1.0 mm), the distance (H ₀ ) in the center in the vertical direction and the width After measuring the length (L ₀ ) in the center of the direction with a caliper to a minimum scale of 0.05 mm, liquid flow treatment (temperature: 120 ° C., flow rate) using a dyeing tester [Wins dyeing machine manufactured by Texam Giken Co., Ltd.] : 200 to 300 L / min), and the length (H ₁ ) of the central portion in the vertical direction and the length (L ₁ ) of the central portion in the horizontal direction after drying at 120 ° C. for 20 minutes were measured. The shape change rate (%) was calculated from the following equation.
Shape change rate (%) = [{(H ₁ −H ₀ ) / H ₀ } × 100 + {(L ₁ −L ₀ ) / L ₀ } × 100] / 2

[Texture]
For the textures of the leather-like sheets prepared in Examples 1 to 7 and Comparative Examples 1 to 4, a sensory test based on the feel of the hand was performed. The case where the softness was slightly inferior to leather was judged as “△”, and the case where it did not exhibit a natural leather-like texture due to lack of softness was judged as “X”.

  The leather-like sheet obtained by the production method of the present invention can be used for various purposes, for example, mattresses, because the production method of the present invention can produce a leather-like sheet that is excellent in strength and texture and is similar to natural leather. , Lining materials, clothing, shoe core materials, cushioning fabrics, automobile interior materials and wall materials.

Claims (4)

A fibrous base material is impregnated or coated with a polyurethane resin emulsion (Q) having a heat-sensitive coagulation property comprising a polyurethane resin (A), a plasticizer (B), a heat-sensitive coagulant (C) and an aqueous medium (D). A method for producing a leather-like sheet comprising a step, a step of thermally coagulating (Q) after the step and a water washing step, wherein the method satisfies the following (1) to (7).
(1) The weight ratio [(A) :( B)] of (A) and (B) is 99: 1 to 40:60.
(2) 10 g or more of (B) is dissolved in 100 g of water at 25 ° C.
(3) The solubility parameter (SP value) of (B) is 9.2 to 12.5.
(4) The storage elastic modulus at 100 ° C. of the film obtained by drying (Q) is 0.01 to 0.1 MPa.
(5) The storage elastic modulus at 100 ° C. of the film obtained by drying the polyurethane resin emulsion (Q ′) not containing only (B) among the constituent components of (Q) is 0.5 to 10 MPa. .
(6) The thermal coagulation temperature of (Q) is 40 to 90 ° C.
(7) The weight (Wb2) of (B) per unit area in the produced leather-like sheet is divided by the weight (Wb1) of (B) per unit area of the fibrous base material after the thermal coagulation step. The residual rate (X) of (B) obtained is 5% by weight or less.   (A) is a polyurethane resin obtained by reacting polyisocyanate (a2) with polyether diol (a11) and / or polycarbonate diol (a122), or (a2) with polyether diol (a11) and The production method according to claim 1, which is a polyurethane resin obtained by reacting a polycarbonate diol (a122) with a chain extender (a3) and / or a hydrophilic group-containing active hydrogen compound (a4).   The method for producing a leather-like sheet according to claim 1 or 2, wherein (B) is an alkylene oxide adduct having 2 to 4 carbon atoms of a 1 to 6-valent aliphatic alcohol (B1) having 1 to 10 carbon atoms.   The method for producing a leather-like sheet according to claim 1 or 2, wherein (B) is polyethylene glycol having a number average molecular weight of 200 to 1,000 and / or polypropylene glycol having a number average molecular weight of 200 to 1,000. .