JP3090860B2 - Porous sheet and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous sheet having good texture and excellent durability. More specifically, it is a porous sheet obtained by using a polyurethane having a specific chain structure, which is excellent in various physical properties such as mechanical properties and durability, and excellent in wet coagulability when producing it, Further, the present invention relates to a porous sheet suitable for a leather-like sheet, which is excellent in workability such as embossing property when embossing the obtained porous sheet.

[0002]

2. Description of the Related Art Conventionally, a solution of a polymer mainly composed of a polyurethane resin is applied to a support such as a film or impregnated and / or applied to a fibrous structure such as a nonwoven fabric. It is known that a porous sheet can be obtained by coagulating the resin by immersing it in a solution that is a solvent and constituting the resin solution, that is, by so-called wet coagulation. By laminating the porous sheet produced by such a method on the surface of the fabric, and when integrated with the fibrous structure, as it is,
Used as a leather-like sheet.

[0003] The performance required of a porous sheet used for a leather-like sheet is that the sheet does not deteriorate in strength (that is, it has excellent durability) due to long-term storage or use, and that it is flexible. Being sufficiently flexible even under low temperature conditions, and having a surface state similar to that of natural leather (that is, excellent texture),
Furthermore, in order to obtain such a porous sheet having a soft and excellent texture, it is necessary to obtain a sufficiently porous state by wet coagulation (that is, to have excellent wet coagulation properties). That the surface unevenness similar to natural leather can be imparted to the desired surface shape by embossing on the surface of the porous sheet, and that the porous state is not largely destroyed at the time of imparting (that is, the embossability is excellent). No.

In general, polyurethane is synthesized from a polymer diol such as polyester diol, polyether diol or polycarbonate diol, a diisocyanate compound and a chain extender. In the obtained polyurethane, components derived from the polymer diol are soft. The segment component and the component derived from the diisocyanate compound and the chain extender are called a hard segment component, and the hard segment and the soft segment are alternately present to constitute a polyurethane. The soft segments give the polymer elongation, and the hard segments give the polymer strength and prevent plastic flow.

[0005] JP-B-59-10380 and JP-B-59-10378 disclose that when the soft segment component constituting the polyurethane is polycarbonate diol, the durability of the polyurethane is good. The wet coagulability is poor, and as a method for improving the wet coagulability, two types of polyurethanes in which the weight of nitrogen atoms contained in the isocyanate group in the polyurethane is different by 0.2% or more are mixed, or polycarbonate diol is used. Molecular weight 10
A method is described in which two or more different polyurethanes are mixed. However, even if the wet coagulability of polyurethane is improved by this method, the degree is small, and a porous sheet in a very good porous state cannot be obtained.

JP-A-2-160820 discloses a polyester polycarbonate obtained by using a polycarbonate diol obtained from an aliphatic and / or alicyclic hydrocarbon diol as at least one component of a diol component. It is described that a polyurethane resin composition using bonediol is excellent in mechanical strength, hydrolysis resistance and the like.
However, no reference is made to wet coagulation of this polyurethane. In producing a natural leather-like sheet, in order to impart flexibility to the leather-like sheet, a nonwoven fabric of fibers composed of a plurality of polymers is used as a base layer, and polyurethane is applied to the base layer. The method of extracting and removing at least one polymer with toluene is used.When the polyurethane resin described in this publication is wet-coagulated and then extracted with toluene, a porous sheet having a good porous state and a smooth surface is obtained. It has the disadvantage that it cannot be obtained.

Japanese Patent Publication No. 48-29397 discloses that a polyurethane synthesized from a polyesterdiol obtained from a mixed diol containing dipropylene glycol has good wet coagulation properties and hydrolysis resistance. Are listed. However, polyurethane made of dipropylene glycol-based polyester diol does not have high durability. The publication also discloses polyesterdiols such as polyneopentyl adipate, polyhexene adipate, polybutylene sebacate, polyhexene neopentyl adipate, and polyhexene sebacate. polyurethane is excellent in hydrolysis resistance, wet coagulation property is poor, polyethylene adipate or polybutylene adipate, polyurethane using a polyester diol such as polyethylene diethylene adipate has good wet coagulation property is resistance to hydrolysis Inferior, that is, inferior in durability.

Japanese Patent Publication No. 3-14949 discloses a fibrous base material which is impregnated with a polycarbonate-based polyurethane and forms a microporous body by a wet coagulation treatment. However, the microporous body obtained by this method is
It cannot be said that the porous state is very good. In fact, in the method described in this publication, a porous sheet obtained by wet coagulation of the above-mentioned polycarbonate-based polyurethane is not used for a surface layer requiring a good microporous state.

Further, Japanese Patent Application Laid-Open No. Hei 3-244719 discloses a method for producing a polyurethane resin, which comprises reacting a polycarbonate polyol with an alicyclic polyisocyanate and an aromatic polyisocyanate. Is polyhexamethylene carbonate diol, the alicyclic polyisocyanate is dicyclohexylmethane diisocyanate, and the aromatic polyisocyanate is diphenylmethane diisocyanate. Is obtained. However, the polyurethane obtained by this method has poor wet coagulability as described above, and the sheet obtained by wet coagulation does not have a microporous state and cannot be a flexible sheet.

[0010]

As described above, when a specific polyester diol such as polyethylene adipate is used as the soft segment, the wet coagulability is good and a smooth surface can be obtained. Poor processability, and when polycarbonate or polyetherdiol is used for the soft segment, the processability such as wet coagulation is poor, and the technique of manufacturing a porous sheet by wet coagulation is poor. It was not available for the field. Furthermore, according to the prior art, even if a good flexible porous sheet is obtained, the flexibility is impaired under low temperature conditions. Further, the obtained porous sheet is not always satisfactory in workability such as embossing property when embossing.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a porous material having good wet coagulability, excellent embossability, and excellent durability and flexibility, especially flexibility under low temperature conditions. -To provide a product. The present invention relates to a chain consisting of structural units represented by the following chemical formula (I):
A chain consisting of the structural unit represented by the formula (I) and the following chemical formula (I
Having a chain consisting of the structural units represented by II) in the same or different soft segments, and -OR ₁ -O-CO-O- (I) -OR ₂ -O-CO-R _3- CO- (II) - (O- CH 2 CHR 5) 2 -O-CO-R 4 -CO- (III) and, with respect to the total number of the structural units of formula (I) and (II) (III) The ratio of the number of each of the structural units of the chemical formulas (I), (II) and (III) is 0.1 to 0.8, 0.05 to 0.05.
A porous sheet comprising a polyurethane having a soft segment component of 0.7 and 0.05 to 0.8 and a hard segment component having a chain composed of an aromatic diisocyanate component and ethylene glycol or 1,4-butanediol component. is there. (However, in the above formula, R ₁ is a hydrocarbon group having 5 or 6 carbon atoms which may have a branch,
R ₂ is a tetramethylene group, R ₃ and R ₄ are the same or different alkylene groups having 4 to 8 carbon atoms, and R ₅ is a hydrogen atom or a methyl group. )

Further, the present invention provides a method for producing a porous sheet, in which a polyurethane sheet obtained by applying such a polyurethane solution on a support surface and then wet coagulating is peeled off from the support surface. This is a method for producing a porous sheet in which the solution is impregnated and / or applied to the fiber structure and then wet-solidified.

According to the present invention, the above-mentioned object is achieved by having such a structure. However, the present invention simply has the above-mentioned chemical formulas (I), (II) and (III), respectively. An effect far superior to that expected by arithmetic averaging of porous sheets obtained by wet coagulation of different polyurethanes is obtained, and flexibility under low-temperature conditions which is not expected from known matters. The properties and embossability are also satisfied. That is, in general, when polyurethane having excellent durability but poor wet coagulability and polyurethane having excellent wet coagulability but poor durability are mixed and used, a polyurethane having average durability and wet coagulability of both polyurethanes is obtained. That is, in the case of the present invention,
The expected average performance gives much better performance. Thus, the chains composed of the structural units of the above-mentioned chemical formulas (I), (II) and (III) interact with each other to prevent the performance from being deteriorated due to the fact that they are originally mixed. I think that the.

Specific examples of the chain composed of the structural units represented by the above formula (I) include 1,6-hexanediol, 3-methyl-1,5-pentanediol and 1,5
-Pentanediol and the like linked by a carbonate bond, that is, polyhexamethylene carbonate diol, polymethylpentane carbonate diol, polypentamethylene carbonate diol, and the like. Among them, one in which 1,6-hexanediol is linked by a carbonate bond is preferable. The polymer diol having a chain consisting of the structural unit represented by the chemical formula (I) is, for example, 1,6-hexanediol, 3-methyl-
By reacting 1,5-pentanediol or 1,5-pentanediol with diaryl carbonate or dialkyl carbonate under reduced pressure, or 1,6-hexanediol, 3-methyl-1,5-pentanediol or It is obtained by reacting 5-pentanediol and a cyclic alkylene carbonate under reduced pressure. Examples of the diaryl carbonate include diphenyl carbonate, examples of the dialkyl carbonate include dimethyl carbonate and diethyl carbonate, and examples of the cyclic alkylene carbonate include ethylene carbonate. If the group represented by R ₁ is not a hydrocarbon group having 5 to 6 carbon atoms, the object of the present invention cannot be achieved. For example, in the case of a nonamethylene group or the like, coagulation is not sufficient, and smoothness after wet coagulation is not obtained. A porous sheet cannot be obtained.

Specific examples of the structural unit represented by the chemical formula (II) include tetramethylene adipate and tetramethylene sebacate. These chains are obtained by condensation polymerization of tetramethylene glycol and adipic acid or tetramethylene glycol and sebacic acid. In the chain consisting of the structural units represented by the chemical formula (II), when R ₂ is not a tetramethylene group, the above-mentioned flexibility under low-temperature conditions cannot be obtained, or a smooth porous sheet can be obtained. There is a drawback that there is no. Also R
_{Even when the} group represented by ₃ is not an alkylene group having 4 to 8 carbon atoms, there are disadvantages such as insufficient flexibility and a difficulty in obtaining a smooth porous sheet. Of these, tetramethylene adipate is preferred.

Specific examples of the structural unit represented by the above formula (III) include diethylene adipate, dipropylene adipate, diethylene sebacate, and dipropylene sebacate. The chain consisting of these structural units is
It can be obtained by condensation polymerization of diethylene glycol and adipic acid or sebacic acid, or dipropylene glycol and adipic acid or sebacic acid. Of course, diethylene glycol and dipropylene glycol may be used as a mixture. In the chain consisting of structural units represented by the chemical formula (III), - when the (O-CH ₂ CHR ₅₎ there is no group represented by ₂ -O- is not smooth porous sheet is obtained Also, when the group represented by R ₄ is not an alkylene group having 4 to 8 carbon atoms, there is a disadvantage that a smooth porous sheet cannot be obtained. Of these, diethylene adipate and dipropylene adipate are preferred. In the present invention, the above structural units (I), (II) and (II)
The number of links in I) is 1 or more.

Representative methods for obtaining the polyurethane used in the present invention include the following three methods. In the same molecule, a polymer diol having a chain consisting of the structural unit of the chemical formula (I), a chain consisting of the structural unit of (II), and a chain consisting of the structural unit of (III) is synthesized.
A method of reacting this polymer diol, a diisocyanate compound and a chain extender to obtain a polyurethane. In the molecule, a polymer diol having a chain consisting of the structural unit of the chemical formula (I), a polymer diol having a chain consisting of the structural unit of the chemical formula (II), and a chain having the structural unit of the chemical formula (III) A method of mixing a polymer diol having the same and reacting the mixed diol with a diisocyanate compound and a chain extender to obtain a polyurethane. A polyurethane obtained by reacting a polymer diol having a chain consisting of the structural unit of the chemical formula (I) with a diisocyanate compound and a chain extender;
A polyurethane obtained by reacting a polymer diol having a chain consisting of a structural unit of the following formula, a diisocyanate compound and a chain extender, a polymer diol having a chain consisting of a structural unit of the above formula (III), a diisocyanate compound and a chain extender A polyurethane obtained by reacting the above.

In particular, the above-mentioned method further comprises a chain of the above-mentioned chemical formulas (I), (II) and (III) in the same molecule and comprises structural units of the following chemical formulas (IV) and (V) A more preferred method is to synthesize a polymer diol having a chain and react the polymer diol with a diisocyanate compound and a chain extender to obtain a polyurethane. —OR ₂ —O—CO—O— (IV) — (O—CH ₂ CHR ₅ ) ₂ —O—CO—O— (V) (where R ₂ and R ₅ are the same as above) At this time, [(IV) + (V)] / [(II) + (III) + (I
V) + (V)] is preferably in the range of 0.05 to 0.8, particularly 0.1 to 0.6.

In the present invention, a method other than the above methods (1) to (3), for example, a method using the above and the above in combination, for example, a chain consisting of the structural unit of the chemical formula (II) and a chain consisting of the structural unit (III) A method of obtaining a polyurethane by mixing a polymer diol having the same molecular unit with a polymer diol having a chain composed of the structural unit of the formula (I), and reacting the mixed diol with a diisocyanate compound and a chain extender to obtain a polyurethane. Good.

Among them, the above-mentioned method is particularly preferable, in which the effect of the interaction of the chains composed of the structural units of the formulas (I), (II) and (III) can be greatly expected. And the above method is used in combination, and the second preferable method is the above method. In the case of the above method, the structural unit represented by the chemical formula (I), the structural unit represented by the formula (II) and the structural unit represented by the formula (III) exist in the same soft segment. Become. In the case of the above method, only one of the structural units represented by the chemical formulas (I), (II) and (III) exists in the same soft segment. Usually they will be present together in the molecule. In the case of the above method, the same chemical formula (I) is contained in the same polyurethane molecule.
Only one of the structural units represented by (II) and (III) will be present. The polyurethane in the present invention includes a mixture obtained by simply mixing two or more polyurethanes, which is obtained by the above-mentioned method.

In the present invention, the chemical formulas (I) and (I)
The ratio of the number of each of the structural units of the above formulas (I), (II) and (III) to the total number of the structural units of I) and (III) [hereinafter, this ratio is represented by (I) /） (I) +
(II) + (III)｝, (II) / ｛(I) + (II) + (II
I) {, (III) / {(I) + (II) + (III)}] are 0.1 to 0.8, 0.05 to 0.7, and 0.05 to 0.5.
Must be 0.8. Here, the number of structural units refers to the chemical formula (I) present in the polyurethane,
Each molecule of (I), (II) and (III) relative to the total number of molecules of (I), (II) and (III) when each structural unit of (II) and (III) is one molecule It means a percentage of numbers.

A ratio of the structural unit represented by the chemical formula (I),
That is, when (I) / {(I) + (II) + (III)} is less than 0.1, a porous sheet excellent in durability cannot be obtained, and conversely, when it exceeds 0.8. In this case, a smooth and flexible porous sheet in a favorable porous state cannot be obtained, and the embossing property is further deteriorated. Preferably (I) /
{(I) + (II) + (III)} is in the range of 0.2 to 0.7, more preferably in the range of 0.25 to 0.6.

The ratio of the structural unit represented by the chemical formula (II), that is, (II) / {(I) + (II) + (III)}
If is less than 0.05, a porous sheet in a good porous state cannot be obtained, and the surface has irregularities. On the other hand, when it exceeds 0.7, problems such as lack of durability and poor flexibility at low temperatures occur. Preferably it is in the range of 0.07 to 0.65, more preferably in the range of 0.1 to 0.6.

Further, the ratio of the structural unit of the formula (III):
That is, (III) / {(I) + (II) + (III)} is
As described above, it is in the range of 0.05 to 0.8, and 0.0
If it is less than 5, the flexibility at low temperatures is inferior. As described above, the porous sheet of the present invention is used for a base layer or a surface layer of a leather-like sheet, and the leather-like sheet is processed into shoes or bags, but is flexible at low temperatures. When the properties are poor, the wearing comfort as a shoe under low temperature is deteriorated, and in some cases, the porous sheet is cracked or broken. Conversely, if it exceeds 0.8, the durability will be poor. Preferably it is in the range of 0.07 to 0.7, more preferably 0.1.
０0.6.

In the case of the above-mentioned method, that is, when the chain composed of the structural units of (I), (II) and (III) is copolymerized at the stage of the polymer diol, (I ), The structural unit of (II) and the structural unit of (III) undergo an exchange reaction during the synthesis of the polymer diol, and (I), (II) and (III) in the resulting polymer diol ) And (I) used as raw materials and (I)
The ratio of the structural units of (I) and (III) may be different.
Therefore, the obtained polymer diol was analyzed by NMR,
It is important to determine the respective proportions of the structural units (I), (II) and (III). Then, when the exchange reaction occurs, the structural units (IV) and (V) described above are generated. The degree of the exchange reaction can be changed by adjusting the temperature and time during the synthesis. On the other hand, in the case of mixing the high-molecular diol at the stage of synthesizing the polyurethane or after the synthesis as in the above method, the exchange reaction does not substantially occur, and the (I) ), (II) and (III), the ratio of the structural units can be substantially maintained in the polyurethane obtained.

The number average molecular weight of the high molecular weight diol containing the structural units of the formulas (I), (II) and (III) used in the polyurethane of the present invention in the same or different molecules may be from 700 to 4,000. Preferably, it is more preferably in the range of 1000-2500. If it is less than 700, when used for a leather-like sheet, the resulting leather-like sheet tends to lose its flexibility or have a reduced texture. In addition, those exceeding 4000 are probably due to the urethane group concentration decreasing,
A porous sheet with a good balance of cold resistance, heat resistance and durability
Not only is difficult to obtain, but also industrial production of the polymer diol becomes difficult.

The polyurethane used in the present invention has the following soft segments (I), (II) and (II).
It contains a chain consisting of the structural units of I),
(I), (II) and (II) within a range not to impair the present invention.
Mixing and using a polymer diol which does not contain the structural unit of I) and which is used for ordinary polyurethane can be used at all. Such as polyester geo-
, Polyetherdiol, polylactonediol, polycarbonate diol and the like. Further, the polymer diol having at least one of the structural units (I), (II) and (III) is a structural unit other than (I), (II) and (III) within a range not to impair the present invention. May be included as such a structural unit,
Other than the structural units of (I), (II) and (III), there may be mentioned polyester chains, polyether chains, polycarbonate chains, polylactone chains and the like.

The diisocyanate compound used in the present invention is an aromatic diisocyanate as described above, for example, diphenylmethane-4,4'-diisocyanate, 2,4- or 2,6-tolylene diisocyanate. Net, meta or paraphenylene diisocyanate,
1,5-naphthylene diisocyanate and the like. Of these, diphenylmethane-4,4'-diisocyanate is preferred because the processability, the surface properties, the feel, and the durability of the obtained porous sheet are further improved. When the diisocyanate compound is an aliphatic or alicyclic compound, wet coagulability and porous stability during toluene extraction are not sufficient, and a smooth porous sheet cannot be obtained. Of course, a diisocyanate compound other than the aromatic diisocyanate can be used in combination within a range that does not impair the object of the present invention.

The amount of the diisocyanate compound to be used is not particularly limited, but includes the viscosity of the polyurethane solution, the molecular weight of the polymer diol, the reaction solvent, and the moisture contained in the polymer diol and the chain extender. In general, the ratio (NCO / OH) of the NCO group equivalent of the diisocyanate compound to the total equivalent of the terminal hydroxyl group of the polymer diol and the hydroxyl group of ethylene glycol or butylene glycol used as the chain extender is 0. .95-1.2
Is preferable, and particularly preferably in the range of 0.97 to 1.1.

As the chain extender, ethylene glycol or 1,4-butanediol is used in view of stability during extraction with toluene. In the case of other chain extenders, for example, in the case of low molecular diols such as propylene glycol and 1,5-pentanediol and low molecular diamines such as ethylenediamine and hexamethylenediamine, the object of the present invention is not achieved. Of course, low molecular diols other than ethylene glycol and 1,4-butanediol may be used in combination as long as the object of the present invention is not impaired.
The amount of the chain extender used is not particularly limited, but as described above, the total amount of the chain extender and the diisocyanate compound has an (NCO / OH) ratio of 0.95 to 1.2.
Is more preferable, and the range where the number of hydroxyl groups of the chain extender is 1 to 7 with respect to the number of terminal hydroxyl groups of the polymer diol is more preferable in terms of flexibility and wet coagulation.

The polyurethane can be polymerized by any of known polymerization methods such as a melt polymerization method, a solution polymerization method, and a bulk polymerization method. However, since the polyurethane is used in the form of a solution in the production of a porous sheet material, Is preferably a solution polymerization method from the viewpoint of solubility in a solvent. Although a catalyst is not necessarily required at the time of polymerization, catalysts usually used for producing polyurethane, such as titanium tetraisopropoxide, dibutyltin dilaurate, and tin octate
Metal compounds such as tetramethylbutanediamine,
Tertiary amines such as 1,4-diaza (2,2,2) bicyclooctane can be used.

Examples of the polyurethane solvent or the solvent for the above solution polymerization include solvents used as ordinary polyurethane solvents such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, toluene, ethyl acetate, methyl ethyl ketone and tetrahydrofuran. used. Among them, dimethylformamide is particularly preferred for obtaining a flexible and favorable porous porous sheet. The concentration of the polyurethane in the polyurethane solution is preferably from 5 to 50% by weight.

When the polyurethane obtained by such a method is used, various additives used in conventional polyurethane for use, such as a flame retardant such as a phosphorus compound and a halogen-containing compound, an antioxidant, an ultraviolet absorber, a pigment, Plasticizers, surfactants and the like can be added.

The polyurethane solution thus obtained is applied to a release sheet or impregnated and / or applied to a fibrous base material and solidified to be processed into a porous sheet.
Since the polyurethane of the present invention has good wet coagulability,
Wet coagulation is preferred. There is no particular limitation on the wet coagulation method, and a method usually performed in the artificial leather industry can be applied, for example,
By using a composition having a polyurethane concentration of 10 to 30% by weight, the mixture weight ratio of the polyurethane solvent and water is substantially 55%.
/ 45 to 0/100 at a temperature of 20 to 55 ° C. for coagulation.

The fibers constituting the fibrous structure impregnated and / or coated with the polyurethane solution are not particularly limited, but ordinary fibers such as natural fibers such as cotton, hemp and wool, and regenerated fibers such as rayon and acetate Alternatively, synthetic fibers such as semi-synthetic fibers, polyester, polyamide, polyacrylonitrile, and vinylon are exemplified. In the case of synthetic fibers, not only single spun fibers but also mixed spun fibers or composite spun fibers may be used.

When a mixed spun fiber or a conjugate spun fiber is used, at least one polymer from among a plurality of polymers constituting the fiber is extracted or decomposed and removed at any stage of producing a leather-like sheet. Is preferred.
By extracting and removing, the fiber structure becomes supple,
A leather-like sheet made of such a pliable fiber structure also has a supple luxury feeling. In particular, the average fineness of the fiber is reduced to 0.
In the case of a bundle of 0.0005 to 0.3 denier ultrafine fibers, if a so-called suede-like leather-like sheet having nap fibers on the surface is used, the surface will have nap of ultrafine fibers, giving a sense of quality. A leather-like sheet is obtained. Similarly, in the case of forming a bundle of the ultrafine fibers, a leather-like sheet having a so-called silver surface layer having a coating layer on the surface is preferable because it has excellent surface smoothness and has a luxurious feeling. .

Such an ultrafine fiber bundle generation type fiber can be obtained by spinning or composite spinning the ultrafine fiber component and an extraction removal or decomposition removal (hereinafter, the extraction removal and the decomposition removal are collectively referred to as extraction removal) component. Can be Examples of the ultrafine fiber component include polyesters such as polyethylene terephthalate and polybutylene terephthalate, 6-nylon,
Examples thereof include polyamides such as 6-nylon, and polyolefins represented by polypropylene. On the other hand, extraction and removal components include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid. Ester copolymer, ethylene-α-olefin copolymer, polystyrene, styrene-isoprene copolymer, hydrogenated styrene-isoprene copolymer, styrene-butadiene copolymer, styrene-
Examples include hydrogenated butadiene copolymers and polyurethane.

[0038] In this case, the polymer as the ultrafine fiber component and the polymer as the extraction / removal component have higher solubility or decomposability in a solvent or a decomposer, and both have low affinity, The combination in which the latter has a lower melt viscosity under spinning conditions than the former is preferred. The average thickness of the ultrafine fibers is preferably from 0.0005 to 1 denier, more preferably from 0.0005 to 0.3 denier.

There is no particular limitation on the method for producing the ultrafine fiber-generating fiber. For example, a polymer as an ultrafine fiber component and a polymer as an extraction / removal component are mixed at a predetermined mixing ratio and melted in the same melting system. A method of forming a mixed flow and spinning it, a method of melting the mixture in separate melting systems, repeating the joining-division multiple times at the spinning machine head to form a mixed flow and spinning the mixed flow, It is manufactured by a method of melting in a melting system, merging at a spinneret of a spinning machine and spinning this. Since the polymer component as the microfiber component and the polymer as the extraction / removal component do not have an affinity, both polymers are separated into a sea-island shape (the microfiber component becomes an island component) or a multilayer laminate in the fiber cross section. It will exist in a state where it has been done. In particular, the amount of the polymer as the ultrafine fiber component in the fiber is 40 to 80% by weight, and the number of the ultrafine fiber component present in the fiber cross section is 5 or more, preferably 50 to 8
Ultrafine fiber generating fibers in the range of 00 fibers are preferred. The ultrafine fiber-generating fiber is converted into an ultrafine fiber through a normal fiber processing step such as drawing or heat setting, if necessary.

Further, a fiber in which the ultrafine fiber-generating fiber and the sea-island are reversed as described above, that is, sea-island fiber in which the extraction-removed component polymer is an island component is produced. It can also be a porous hollow fiber in the shape of a circle. By extracting and removing island components from such fibers, a leather-like sheet having flexibility similar to supple natural leather can be obtained.

As the fibrous structure, a woven fabric, a knitted fabric, or a non-woven fabric is used.
Particularly, a three-dimensional entangled nonwoven fabric is preferable. The nonwoven fabric may be one in which a knitted fabric for reinforcement or the like is laminated inside as required.

When a non-woven fabric is used as the fibrous structure, the non-woven fabric is obtained by defibrating the above-mentioned fibers with a card,
A random web or a cross wrap web is formed through a web, the obtained fiber web is laminated to a desired weight and thickness, and then the fiber web is subjected to a needle punch, a water jet, an air jet, or the like. It is obtained by subjecting fibers to entanglement.

In such a fibrous structure, a coagulation regulator, a release agent, a plasticizer, a stabilizer, an antioxidant, a light-proofing agent, After adding a coloring agent and the like, the polyurethane solution is impregnated and / or coated, and wet coagulated.

In the case of ultrafine fiber-generating fiber or lotus root fiber-generating fiber, the extraction and removal components constituting the fiber are extracted and removed before or after impregnating and applying the polyurethane solution to the fiber-entangled nonwoven fabric. Into a bundle of ultrafine fibers or a lotus root-like porous hollow fiber.

There is no particular limitation on the amount of polyurethane occupying the sheet-like material composed of the fiber structure and polyurethane, but a leather-like sheet-like material is obtained in a weight fraction of 10 to 60%, especially 15 to 45%. Preferred above. If the amount of the polyurethane used is small, the texture becomes stiff, and particularly if it is less than 10%, it becomes remarkable. If the amount of polyurethane is large, it tends to become hard or have a texture without swelling, especially 60%
When it is used beyond the range, the tendency becomes remarkable.

To the fibrous structure thus impregnated with polyurethane and solidified, a porous material obtained from the above-mentioned polyurethane is applied to the surface, if necessary, and then a non-porous coating layer is applied. In the case of a fibrous structure which has been impregnated and applied and then solidified, a non-porous coating layer is provided if necessary. And further embossing treatment to give a surface grain similar to natural leather, so
Can be.

As described above, the porous sheet of the present invention is not limited to the method of directly impregnating and applying a polyurethane solution to a fiber structure, but the method of applying a polyurethane solution to a support surface such as a polyethylene sheet. After that, a method may be used in which the porous sheet obtained by wet coagulation is peeled off from the support surface, and then the porous sheet is bonded on the fiber structure. By embossing the surface of the bonded porous sheet to give a surface texture similar to natural leather, a leather-like sheet with a grained surface can be obtained.

Further, by raising at least one surface of the above-mentioned fibrous structure impregnated and coagulated with polyurethane, it is possible to obtain a fibrous raised suede-like leather-like sheet. Further, if necessary, it can be slice-divided into an arbitrary thickness in the thickness direction at an arbitrary stage. When the porous sheet of the present invention is obtained by impregnating the fibrous structure with polyurethane and coagulating it, the thickness of the porous sheet is preferably 0.2 to 3 mm after slicing. In the case where the porous sheet is applied and solidified on a fiber structure or solidified on a support, the thickness of the porous sheet is 0.05 to 0.5 m.
m, and the density is preferably from 0.3 to 0.5 g / cm ³ .

As a method for evaluating the wet coagulability of polyurethane, for example, a solution having a polyurethane concentration of 10 to 30% by weight is applied to a release substrate such as polyethylene sheet, and this is wet coagulated. A porous seal obtained by peeling the obtained polyurethane coating layer from the substrate.
The surface smoothness of the sheet, the ratio of the thickness of the sheet after coagulation to the thickness of the applied polyurethane solution (hereinafter, this ratio is referred to as the thickness retention), the uniformity of the pores observed in the cross section of the porous sheet, etc. Can be evaluated. The surface smoothness, thickness ratio, and pore size vary depending on the polyurethane solution concentration, coagulation bath temperature and concentration, etc.
It is judged that a polyurethane having a good coagulation property is obtained when the thickness retention rate is in the range of 40 to 70% and the surface smoothness and uniformity of pores during coagulation are high under the same conditions. That is, in the case of polyurethane having poor coagulation property, it significantly shrinks during coagulation or coagulation proceeds unevenly, so that the surface smoothness is impaired, and the size and distribution of pores tend to be nonuniform.

The porous sheet of the present invention thus obtained is
Can be suitably used as a resin impregnated in the base layer of the leather-like sheet or as a surface coating layer because of its excellent wet coagulability and embossing property, and such a leather-like sheet is more durable, It is excellent in flexibility, especially under low temperature conditions, surface smoothness and texture, and is useful for various uses such as clothing, shoes, bags, furniture, interior materials for vehicles, and miscellaneous goods. Such excellent performance is obtained by using a polyurethane having a specific structure.

[0051]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. Example 1 As a chain consisting of the structural unit represented by the chemical formula (I), 400 parts by weight of polyhexamethylene carbonate-diol having a molecular weight of 2,000 was used, and a chain consisting of the structural unit represented by the chemical formula (III) 200 parts by weight of polydiethylene adipate diol having a molecular weight of 2,000 as a chain, and 4 parts of polytetramethylene adipate diol having a molecular weight of 2,000 as a chain composed of the structural unit represented by the chemical formula (II).
00 parts by weight, 12 parts by weight of ethylene glycol as a chain extender
4.1 parts by weight, 638.2 parts by weight of diphenylmethane-4,4'-diisocyanate as a diisocyanate compound and dimethylformamide (DM
F) (abbreviated as F), charged into a reactor, reacted under a nitrogen stream, and had a solid content of 25%, a viscosity of 413 poise (30 ° C.), and (I) / ｛(I). +
(II) + (III)｝, (II) / ｛(I) + (II) + (II
A polyurethane solution (A) was obtained in which (I)｝ and (III) / {(I) + (II) + (III)} were 0.49, 0.35 and 0.16, respectively.

Using this polyurethane solution (A), the following polyurethane composition solutions (A-1) and (A-2) were obtained. Polyurethane composition liquid (A-1) Polyurethane solution (A) 720 parts by weight Sorbitan monostearate 10.8 parts by weight Stearyl alcohol 5.4 parts by weight Black pigment 2.0 parts by weight DMF 261.8 parts by weight Total 1000.0 parts by weight Polyurethane composition liquid (A-2) Polyurethane solution (A) 480 parts by weight Chris Bon Assister SD-14 5 parts by weight (trade name, manufactured by Dainippon Ink Co., Ltd.) Black pigment 2 parts by weight DMF 513 parts by weight Total 1000 parts by weight

A three-dimensional entangled nonwoven fabric having a weight of 400 g / m ² and a thickness of 2.5 mm made of spun fibers of 3 denier nylon 6 / polystyrene (weight ratio: 45/55, island component being polystyrene) was used. The above-mentioned polyurethane composition liquid (A) was impregnated with an aqueous alcohol solution, dried, compressed and fixed to a thickness of 2.1 mm, and the surface was smoothed by buffing and having a thickness of 1.7 to 1.8 mm. -1) was impregnated 4.4 times the weight of the nonwoven fabric to smooth the surface. Next, the polyurethane composition solution (A-2) was applied at 80 g / m ² and immersed in an aqueous solution containing 40% by weight of DMF at 45 ° C. for 30 minutes to solidify both the impregnated layer and the coated layer.

[0054] Then, for about 2 hours dipping in a hot water of 50 ° C. to 60 ° C., then was sufficiently desolvation washed (DMF removed), Shiboeki further 80 ° C. 1 hour in hot water of the immersion The process was repeated six times to elute and remove the polyvinyl alcohol used for fixing the nonwoven fabric. Hot air drying at 80 ° C
After the back surface of the sheet-like material is cut off to a thickness of 1.5 to 1.6 mm, it is immersed in toluene heated to 80 ° C., and the nylon 6-polystyrene mixed spun fiber used for the nonwoven fabric is removed. Polystyrene was extracted and removed to obtain a lotus root-shaped porous hollow fiber, and then toluene contained in the substrate was expelled by steam distillation, followed by heating at 100 ° C. for drying.

The obtained sheet had a soft and stiff feel for both the impregnated layer and the coated layer, and the polyurethane was in an extremely porous state having pores of uniform size. Particularly, the holding ratio of the thickness of the surface coating layer is 49%.
Good and smooth. 7
Exposure was performed for 8 weeks in an atmosphere of 0 ° C. and a relative humidity of 95%.
No change in appearance was observed, the surface was smooth and the texture was good. Also the sheet under the condition of -5 ° C. - pull the door, was bend, almost no change in flexibility at normal temperature, even under low temperature conditions, it was found to be very flexible. When the coating layer side of this sheet was thermocompression-bonded to an embossing roll having a natural leather-like uneven pattern, the coating layer surface was clearly provided with an uneven pattern, and was extremely flexible, similar to natural leather. It had a texture and appearance, and was of great industrial value.

Comparative Example 1 500 parts by weight of polyhexamethylene carbonate diol having a molecular weight of 2000, 500 parts by weight of polytetramethylene adipatediol having a molecular weight of 2,000, and ethylene glycol
124.1 parts by weight, 640.1 parts by weight of diphenylmethane-4,4'-diisocyanate and DMF5290
A part by weight was charged into the reactor and reacted under a nitrogen stream to obtain a polyurethane solution (B) having a solid content of 25% and a viscosity of 420 poise (30 ° C.). This polyurethane does not have a chain composed of the structural unit of the formula (III) specified in the present invention. Polyurethane composition liquids (B-1) and (B-2) were obtained in the same manner as in Example 1 except that the polyurethane solution (B) was used instead of the polyurethane solution (A). After coagulation and toluene extraction, a sheet was obtained. The obtained sheet has a low coating layer thickness retention rate of 36%, and has numerous irregularities on the surface, extremely irregular pore sizes, and has a hard texture including the impregnated layer. Was of low value. When an embossed pattern was applied to this sheet in the same manner as in Example 1 above,
The portion where the embossed pattern was tight and the portion where the embossed pattern was hardly contained existed in an uneven mottled state, and could not be said to have a natural leather-like appearance.

Comparative Example 2 Polydiethylene adipatediol 3 having a molecular weight of 2000
33 parts by weight, 667 parts by weight of polytetramethylene adipatediol having a molecular weight of 2000, ethylene glycol 12
4.1 parts by weight, 629 parts by weight of diphenylmethane-4,4'-diisocyanate and 5290 parts by weight of DMF are charged into a reactor and reacted under a nitrogen stream to obtain a solid content of 25 parts by weight.
%, A polyurethane solution (C) having a viscosity of 400 poise (30 ° C.) was obtained. This polyurethane does not have a chain composed of the structural unit represented by the chemical formula (I) specified in the present invention. Polyurethane composition liquids (C-1) and (C-2) were obtained in the same manner as in Example 1 except that the polyurethane solution (C) was used instead of the polyurethane solution (A).
Subsequently, the processed nonwoven fabric was impregnated, coated, solidified, and extracted with toluene to obtain a sheet. The obtained sheet had a coating layer thickness retention rate of 51%, had a smooth surface, and had good feeling in both the impregnated layer and the coat layer.
When exposed to an atmosphere of 5% for 5 weeks, countless cracks were generated on the surface of the coat layer, and the durability was extremely insufficient. It had a major problem and was of low industrial value.

Comparative Example 3 500 parts by weight of polyhexamethylene carbonate diol having a molecular weight of 2,000, 500 parts by weight of polydiethylene adipatediol having a molecular weight of 2,000, 124.1 parts by weight of ethylene glycol, and diphenylmethane-4,4 '-Diisocyanate (642 parts by weight) and DMF (5290 parts by weight) were charged into a reactor and reacted under a nitrogen stream to obtain a solid content of 2%.
A polyurethane solution (D) having a viscosity of 5% and a viscosity of 400 poise (30 ° C.) was obtained. This polyurethane does not have a chain consisting of the structural unit represented by the chemical formula (II) specified in the present invention. Polyurethane composition liquids (D-1) and (D-2) were obtained in the same manner as in Example 1 except that the polyurethane solution (D) was used instead of the polyurethane solution (A).
Subsequently, the processed nonwoven fabric was impregnated, coated, solidified, and extracted with toluene to obtain a sheet. The obtained sheet had a coating layer thickness retention of 51%, a smooth surface, and both the impregnated layer and the coat layer had good flexibility and hand, but at -5 ° C.
The flexibility is greatly impaired under the conditions described above, and it is used under low-temperature conditions, and also has a great problem as an artificial leather such as a bag or a shoe that requires flexibility under such conditions. Was of low utility value.

Example 2 400 parts by weight of polyhexamethylene carbonate diol having a molecular weight of 2,000 as a high molecular weight diol, and a molecular weight of 20
Chain extension using 300 parts by weight of polydiethylene adipatediol of 2000, 200 parts by weight of polytetramethylene adipatediol of 2000 molecular weight, and 100 parts by weight of polytetramethylene glycol of 2000 molecular weight. 138.7 parts by weight of ethylene glycol as an agent and diphenylmethane-4,4'- as a diisocyanate compound
Using 705 parts by weight of diisocyanate and 5530 parts by weight of DMF as a reaction solvent, these were charged into a reactor, reacted under a nitrogen stream, and had a solid content of 25% and a viscosity of 4%.
25 poise (30 ° C.) and (I) / ｛(I) + (I
I) + (III)｝, (II) / ｛(I) + (II) + (II
A polyurethane solution (E) was obtained in which (I)｝ and (III) / {(I) + (II) + (III)} were 0.54, 0.19 and 0.27, respectively.

Using the above polyurethane solution (E), the following polyurethane composition liquids (E-1) and (E-2) were obtained. Polyurethane composition liquid (E-1) Polyurethane solution (E) 560 parts by weight Sorbitan monostearate 10.8 parts by weight Stearyl alcohol 5.4 parts by weight DMF 423.8 parts by weight Total 1000.0 parts by weight Polyurethane composition Liquid (E-2) Polyurethane solution (E) 480 parts by weight Chris Bon Assister-SD-145 5 parts by weight (Coagulation regulator manufactured by Dainippon Ink Co., Ltd.) Titanium oxide 2.9 parts by weight DMF 512.1 parts by weight Total 1000.0 parts by weight

The polyurethane composition liquids (A-1) and (A)
A sheet was obtained in the same manner as in Example 1 except that the above polyurethane composition liquids (E-1) and (E-2) were used instead of -2). In the obtained sheet, both the impregnated layer and the coat layer had a soft and stiff texture, and the polyurethane was in an extremely porous state having pores of uniform size. The retention rate of the thickness of the surface coating layer was as good as 48% and smooth. The obtained sheet was exposed to an atmosphere at 70 ° C. and a relative humidity of 95% for 8 weeks. No change in appearance was observed, and the sheet had a smooth surface and a good texture. It was also found that there was almost no change in the flexibility at room temperature even under the condition of -5 ° C., and that it was extremely flexible even under the low temperature condition. When the coating layer side of this sheet was thermocompression-bonded to an embossing roll having a natural leather-like uneven pattern, the coating layer surface was clearly provided with an uneven pattern, and was extremely flexible, similar to natural leather. It had a texture and appearance, and was of great industrial value. That is, even if a small amount of a chain other than the chain consisting of the structural units represented by the chemical formulas (I), (II) and (III) defined in the present invention is present in the soft segment,
It can be seen that the excellent performance of the present invention is hardly impaired.

Comparative Example 4 570 parts by weight of polyhexamethylene carbonate diol having a molecular weight of 2,000, 290 parts by weight of polytetramethylene adipatediol having a molecular weight of 2,000, 140 parts by weight of polytetramethylene glycol having a molecular weight of 2,000, 138.7 parts by weight of ethylene glycol, diphenylmethane-4,
707 parts by weight of 4'-diisocyanate and DMF55
35 parts by weight are charged into a reactor and reacted under a nitrogen stream.
A polyurethane solution (F) having a solid content of 25% and a viscosity of 425 poise (30 ° C.) was obtained. This polyurethane does not have a chain composed of the structural unit represented by the chemical formula (III) specified in the present invention. A polyurethane solution (F) was used in place of the polyurethane solution (E), and the obtained polyurethane composition liquids (F-1) and (F-2) were replaced with polyurethane composition liquids (E-1) and (E-2). A sheet was obtained in the same manner as in Example 2 except that the sheet was used. However, the obtained sheet had a low coating layer thickness retention rate of 33% and had countless irregularities on the surface. Both of the coat layers had a slightly hard texture and were of low industrial value. When an embossed pattern was applied to this sheet in the same manner as in Example 1, the portion where the embossed pattern was tight and the portion where almost no embossed pattern were present were present in an uneven mottled state, and had a natural leather-like appearance. I couldn't say that.

COMPARATIVE EXAMPLE 5 800 parts by weight of polyhexamethylene carbonate diol having a molecular weight of 2,000, 200 parts by weight of polytetramethylene glycol having a molecular weight of 2,000, and ethylene glycol 13
8.7 parts by weight, 706 parts by weight of diphenylmethane-4,4'-diisocyanate, and 5530 parts by weight of DMF were charged into a reactor, and reacted under a nitrogen stream to obtain a solid content of 25%.
Polyurethane solution (G) with a viscosity of 450 poise (30 ° C)
I got This polyurethane does not have a chain composed of the structural units represented by the chemical formulas (II) and (III) specified in the present invention. The polyurethane solution (G) was used in place of the polyurethane solution (E), and the obtained polyurethane composition liquids (G-1) and (G-2) were replaced with polyurethane composition liquids (E-1) and (E-2). A sheet was obtained in the same manner as in Example 2 except that the sheet was used in the same manner as in Example 2. However, the retention rate of the coat layer thickness of the obtained sheet was as low as 31%. The impregnated layer was also hard and of low industrial value.

Example 3 400 parts by weight of polyhexamethylene carbonate diol having a molecular weight of 2,000 as a high molecular weight diol and a molecular weight of 20
Of polydipropylene adipate diol having a molecular weight of 2000 and 250 parts by weight of
350 parts by weight of ethylene glycol, 124.1 parts by weight of ethylene glycol as a chain extender, and 6 parts of diphenylmethane-4,4'-diisocyanate as a diisocyanate compound.
Using 40 parts by weight of DMF and 5290 parts by weight of DMF as a reaction solvent, these were charged into a reactor and reacted under a nitrogen stream, and the solid concentration was 25% and the viscosity was 400 poise (30 ° C.)
And (I) / {(I) + (II) + (III)}, (I
I) / {(I) + (II) + (III)} and (III) /
{(I) + (II) + (III)} are 0.5 and 0.3, respectively.
A polyurethane solution (H) of 2 and 0.18 was obtained.
Using the above polyurethane solution (H), the following polyurethane composition liquids (H-1) and (H-2) were obtained.

Polyurethane composition liquid (H-1) Polyurethane solution (H) 720 parts by weight Sorbitan monostearate 10.8 parts by weight Stearyl alcohol 5.4 parts by weight Black pigment 2.0 parts by weight DMF 261.8 Parts by weight Total 1000.0 parts by weight Polyurethane composition liquid (H-2) Polyurethane solution (H) 480 parts by weight Crisbon Assister-SD-14 5 parts by weight (Coagulation control agent manufactured by Dai Nippon Ink Co., Ltd.) Black pigment 2 parts by weight DMF 513 parts by weight Total 1000 parts by weight

The sea component is polyethylene, the island component is nylon-6, and the sea / island mixed spun fiber having a weight ratio of 50/50 is melt-spun, wet-heat stretched, crimped, and cut to a length of 51 mm.
3.5 denier fiber (average fineness of island component is 0.003
With denier, the number of island components in the fiber cross section was 600). A web was made from these fibers, laminated and entangled into a woven nonwoven fabric having a basis weight of 640 g / m ² and a thickness of 2.0 mm by a needle punch, and impregnated with the polyurethane composition liquid (H-1) in an amount 2.2 times the weight of the nonwoven fabric. , Smoothed the surface. Next, 80 g / m ^{2 of} a polyurethane composition liquid (H-2) was applied, and 30% aqueous solution containing 40% by weight of DMF at 45 ° C. was applied.
The coating was solidified for both minutes by treating for 1 minute.
Next, it was immersed in toluene heated to 80 ° C., the polyethylene in the nylon-polyethylene mixed spun fiber used for the nonwoven fabric was extracted and removed, and the toluene contained in the substrate was expelled by steam distillation, and 100 ° C. And dried.

The coat layer of the obtained sheet has a good thickness retention of 48%, the impregnated layer and the coat layer both have a soft and stiff feel, and the coat layer has a smooth surface. Met. The resulting sheet is kept at 70 ° C. and 95% relative humidity.
Exposure for 8 weeks under no atmosphere, no change in appearance, smooth surface and good texture, and even under low temperature conditions, flexibility is almost the same as that at normal temperature. It was also excellent in flexibility. In addition, it was excellent in embossability, and had great industrial value as artificial leather.

Comparative Example 6 500 parts by weight of polyhexamethylene carbonate diol having a molecular weight of 2,000, 500 parts by weight of polyethylene glycol having a molecular weight of 2,000, 124.1 parts by weight of ethylene glycol, and diphenylmethane-4,4 ' -Diisocyanate (641.2 parts by weight) and DMF (5290 parts by weight) were charged into a reactor and reacted under a nitrogen stream to obtain a solid content of 25%.
Polyurethane solution (K) with a viscosity of 420 poise (30 ° C)
I got This polyurethane does not have the chains of formulas (II) and (III) as defined in the present invention. Polyurethane composition liquids (K-1) and (K-2) were obtained in the same manner as in Example 1 except that this polyurethane solution (K) was used in place of the polyurethane solution (A). The solid was coagulated and extracted with toluene to obtain a sheet.
The obtained sheet has a low coating layer thickness retention rate of 36%, and has numerous countless irregularities on the surface. The texture, including the impregnated layer, is hard, and the embossability is extremely poor. It was of low value.

Example 4 Using hexanediol, butanediol, diethylene glycol, adipic acid, and dimethyl carbonate, 49.0 mol% of hexanediol residues, 20.3 mol% of butanediol residues, and diethyleneglycol of diol residues were used. Residues are 30.7%, 33.8% of hexanediol residues are bound to adipic acid residues, 66.2% are bound to dimethyl carbonate residues, and 49.7% of butanediol residues. Binds to an adipic acid residue and gives 50.3
% Bind to dimethyl carbonate residues, 63.0% of diethylene glycol residues bind to adipic acid residues, 37.0% bind to dimethyl carbonate residues,
In addition, a copolymerized polyester diol having a number average molecular weight of 2,000 was produced. This copolymerized polyester diol 10
00 parts by weight, 124.1 parts by weight of ethylene glycol, diphenylmethane-4,4'-diisocyanate 638.7
Parts by weight and dimethylformamide (DMF) 5290
Parts by weight were charged into a reactor and reacted under a nitrogen stream. The solid content was 25%, the viscosity was 403 poise (30 ° C.), and (I) / {(I) + (II) + (III)}. (II) /
{(I) + (II) + (III)}, (III) / ｛(I) +
(II) + (III)} and {(IV) + (V)} / {(I
I) + (III) + (IV) + (V)} is 0.49,
Polyurethane solutions (L) were obtained at 0.14, 0.37 and 0.44.

The polyurethane composition liquids (L-1) and (L-2) were obtained in the same manner as in Example 1 except that the polyurethane solution (L) was used in place of the polyurethane solution (A). , Coating, coagulation and toluene extraction to obtain a sheet. The thickness retention of the coat layer of the obtained sheet is as very good as 55%, it has extremely excellent flexibility including the impregnated layer and has a firm feeling, and the surface of the coat layer is smooth. Met. The obtained sheet was exposed to an atmosphere of 70 ° C. and a relative humidity of 95% for 8 weeks, but no change in appearance was observed, the surface was extremely smooth and the texture was good, and even under a low temperature condition. The flexibility was almost the same as that at room temperature, and was excellent in flexibility at low temperature.
It was also extremely excellent in embossability, and was the most luxurious and extremely useful in industrial use as compared with the artificial leather obtained in the above examples.

Example 5 1000 parts by weight of polyhexamethylene carbonate diol having a molecular weight of 2,000, and 124 parts by weight of ethylene glycol.
Using 1 part by weight, 634 parts by weight of diphenylmethane-4,4'-diisocyanate and 5270 parts by weight of DMF as a reaction solvent, these were charged into a reactor, reacted under a nitrogen stream, and reacted at a solid concentration of 25% by weight. A polyurethane solution (M-1) having a viscosity of 410 poise (30 ° C.) was obtained.
Similarly, 1000 parts by weight of polytetramethylene adipate diol having a molecular weight of 2,000 and ethylene glycol 124.
A polyurethane solution (M-2) having a solid content concentration of 25% by weight and a viscosity of 400 poise (30 ° C.) was obtained from 1 part by weight, 634 parts by weight of diphenylmethane-4,4′-diisocyanate and 5270 parts by weight of DMF. Similarly, polydiethylene adipate diol 100 having a molecular weight of 2000
0 parts by weight, 124.1 parts by weight of ethylene glycol, 634 parts by weight of diphenylmethane-4,4'-diisocyanate and 5270 parts by weight of DMF, a polyurethane solution having a solid content of 25% by weight and a viscosity of 390 poise (30 ° C.) ( M-3) was obtained. These polyurethane solutions (M-
1), (M-2) and (M-3) were mixed at a weight ratio of 4: 3: 3 to obtain a mixed polyurethane solution (M). (I) / {(I) + (II) + (III)}, (II) / of the polyurethane constituting this mixed polyurethane solution (M)
{(I) + (II) + (III)} and (III) / {(I) +
(II) + (III)} are 0.49, 0.26 and 0.2, respectively.
25.

480 parts by weight of this polyurethane solution (M), 145 parts by weight of Crisbon Assister SD-
F91 parts by weight were mixed and cast on a polyethylene film to a thickness of 1.0 mm. In this state, DMF / water = 30/7
The resultant was immersed in a coagulation bath at 40 ° C. composed of a 0 (weight ratio) liquid to coagulate, and further washed with water in a water bath at 40 ° C. for 6 hours to completely remove DMF to obtain a porous sheet. The thickness of the obtained sheet is 0.44 mm and the density is 0.45 g / cm.
^{In 3} , the thickness retention was as good as 44%, and it had excellent flexibility and a smooth surface. 70 ° C.
Exposure for 8 weeks in an atmosphere with a relative humidity of 95% showed no change in appearance, a smooth surface and good texture, and the flexibility was almost the same even at low temperatures as at room temperature. And the flexibility at low temperatures was also excellent. This sheet was bonded to the surface of an entangled nonwoven fabric having a thickness of 1.2 mm made of 0.01 denier ultrafine nylon fiber impregnated with polyurethane and solidified, and the surface was embossed. Thus, it had sufficient industrial value as artificial leather. However,
In all respects, it was slightly inferior to the artificial leather obtained in Examples 1-4.

Example 6 In Example 1, 124.1 parts by weight of ethylene glycol used as a chain extender was added to 1,4-butanediol 1
Performed in the same manner as in Example 1 except that the weight was replaced with 80 parts by weight.
Artificial leather was produced. This artificial leather was slightly different from the artificial leather of Example 1 in terms of texture, but had little difference in other performances and was of high industrial value.

Example 7 A porous sheet was obtained in the same manner as in Example 5 except that the polyurethane solution (L) obtained in Example 4 was used. The obtained sheet thickness was as good as 0.51 mm, the density was 0.40, and the thickness retention was 51%, and the sheet had excellent flexibility and smoothness. The resulting sheet was exposed to 70 ° C. and 95% relative humidity for 8 weeks, but no change in appearance was observed, and the sheet was excellent in flexibility at low temperatures.

Example 8 A porous sheet was obtained in the same manner as in Example 5, except that the polyurethane solution (A) obtained in Example 1 was used. The resulting sheet had a thickness of 0.48 mm, a density of 0.42, and a thickness retention of 48%. This porous sheet had excellent flexibility and smoothness. The resulting sheet was exposed to 70 ° C. and 95% relative humidity for 8 weeks, but no change in appearance was observed, and the sheet was excellent in flexibility at low temperatures.

[0076]

The polyurethane porous sheet of the present invention is excellent in wet coagulability during production, excellent in processability such as embossing property when embossing the obtained porous sheet, and further excellent in durability and durability. Excellent flexibility, especially under low temperature conditions, processed into leather-like sheets, clothing, shoes,
It is extremely effective for bags, furniture, vehicle interior materials, miscellaneous goods, and the like.

Claims (4)

(57) [Claims] 1. A chain consisting of a structural unit represented by the following chemical formula (I), a chain consisting of a structural unit represented by the following chemical formula (II), and a chain consisting of a structural unit represented by the following chemical formula (III): Having the same or different soft segments, and -OR ₁ -O-CO-O- (I) -OR ₂ -O-CO-R ₃ -CO- (II)-(O-CH ₂ CHR _{5) 2 -O-CO-R} 4 -CO- (III) and the chemical formula for the total number of structural units of the formula (I) and (II) (III) (I ), (II) and (III ) Is 0.1 to 0.8, 0.05 to 0.5.
A porous sheet comprising a polyurethane having a soft segment component of 7 and 0.05 to 0.8 and a hard segment component having a chain composed of an aromatic diisocyanate component and ethylene glycol or 1,4-butanediol component. (However, in the above formula, R ₁ has 5 to 6 carbon atoms.
R ₂ is a tetramethylene group, R ₃ and R ₄
Represents the same or different alkylene groups having 4 to 8 carbon atoms, and R ₅ represents a hydrogen atom or a methyl group. ) 2. The porous sheet according to claim 1, wherein the polyurethane constituting the porous sheet has a chain composed of structural units of the following chemical formula (IV) and a chain composed of structural units of (V). —OR ₂ —O—CO—O— (IV) — (O—CH ₂ CHR ₅ ) ₂ —O—CO—O— (V) (where R ₂ and R ₅ are the same as above) Meaningful) 3. A chain consisting of a structural unit represented by the following chemical formula (I), a chain consisting of a structural unit represented by the following chemical formula (II), and a chain consisting of a structural unit represented by the following chemical formula (III): In the same or different soft segments, and -OR ₁ -O-CO-O- (I) -OR ₂ -O-CO-R ₃ -CO- (II)-(O-CH ₂ CHR ₅ ) ₂ —O—CO—R ₄ —CO— (III) (wherein, R ₁ is a hydrocarbon group having 5 to 6 carbon atoms,
R ₂ is a tetramethylene group, R ₃ and R ₄ are the same or different alkylene groups having 4 to 8 carbon atoms, and R ₅ is a hydrogen atom or a methyl group. And the ratio of the number of the structural units of the formulas (I), (II) and (III) to the total number of the structural units of the formulas (I), (II) and (III) is 0.1 to 0. .8, 0.05-0.5.
A solution of polyurethane having a soft segment component of 7 to 0.05 to 0.8 and a hard segment component having a chain consisting of an aromatic diisocyanate component and an ethylene glycol or 1,4-butanediol component is coated on a support surface. Then, the porous sheet obtained by wet solidification is peeled off from the support surface. 4. A chain consisting of a structural unit represented by the following chemical formula (I), a chain consisting of a structural unit represented by the following chemical formula (II), and a chain consisting of a structural unit represented by the following chemical formula (III): Having the same or different soft segments, and -OR ₁ -O-CO-O- (I) -OR ₂ -O-CO-R ₃ -CO- (II)-(O-CH ₂ CHR _{5) 2 -O-CO-R} 4 -CO- (III) ( where, in the formula, R ₁ represents a hydrocarbon group having 5 to 6 carbon atoms,
R ₂ is a tetramethylene group, R ₃ and R ₄ are the same or different alkylene groups having 4 to 8 carbon atoms, and R ₅ is a hydrogen atom or a methyl group. And the ratio of the number of the structural units of the formulas (I), (II) and (III) to the total number of the structural units of the formulas (I), (II) and (III) is 0.1 to 0. .8, 0.05-0.5.
A fibrous structure is impregnated with a solution of a polyurethane having a soft segment component of 7 and 0.05 to 0.8 and a hard segment component having a chain composed of an aromatic diisocyanate component and ethylene glycol or 1,4-butanediol component. And / or a method for producing a porous sheet which is wet-solidified after application.