JP2011052336A - Leather-like sheet having excellent alcohol resistance and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leather-like sheet hardly causing color fading and maintaining the flexibility well even when being contacted with an alcohol, and to provide a method for producing the sheet. <P>SOLUTION: The leather-like sheet has a top grain layer containing a coloring agent, and a silicon-modified polyurethane resin having specific characteristics, and coated on the surface of the top grain layer in a dot shape regulated so that the average shortest distance between one dot and the other dot is 10-100 μm. The method for producing the leather-like sheet is also provided. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a leather-like sheet excellent in alcohol resistance and a method for producing the same.

In recent years, as a substitute for natural leather, silver-coated artificial leather with a coat layer laminated on the surface of a base material consisting of a fiber assembly and a polymer elastic body has been used for apparel because of its lightness, easy care, and low price. Widely used for general materials.
In such artificial leather, various colors are formed by kneading pigments or the like on the surface in consideration of use and design.
For artificial leather colored as described above, for example, when the surface is wiped with a cloth to which alcohol is applied in order to remove dirt, the color may be lost. As for the artificial leather capable of preventing this color fading, no effective technique has been found at present.

For example, from the viewpoint of solvent resistance, it is composed of a crosslinkable polyurethane having a hydrolyzable silyl group at the side chain and / or terminal of the molecule and an organic solvent, or hydrolyzing or hydrolyzing these hydrolyzable silyl groups. Artificial leather using a crosslinkable polyurethane resin composed of a condensation catalyst has been proposed (for example, see Patent Document 1).
However, since the artificial leather is not premised on containing a colorant, discoloration is inevitable if a colorant is added. Moreover, since it bridge | crosslinks, when it uses for a coat layer, it will become hard and there exists a problem that a flexibility will fall.

Japanese Patent Laid-Open No. 10-60783

  The present invention provides a leather-like sheet that does not easily lose color even when it comes into contact with alcohol and that can maintain good flexibility, and a method for producing the same.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors applied a specific silicone-modified polyurethane resin in a dot shape (dot shape) under a predetermined condition, that is, without applying the entire coating region. As a result, it was found that (1) the alcohol resistance by the silicone-modified polyurethane resin was sufficiently exhibited, and (2) the problem of lowering the flexibility caused by application to the entire surface could be solved, and the present invention was completed.

That is, the present invention is as follows.
[1] A silicon-modified polyurethane resin having a silver surface layer containing a colorant and having the following characteristics A and B is applied in the form of dots on the surface of the silver surface layer. It is a leather-like sheet having an average shortest distance of 10 to 100 μm between other nearby dots.

Characteristic A: The silicon-modified polyurethane resin is formed into a film having a thickness of 50 μm and a 10 cm square, and the swelling ratio after being immersed in 99.5% ethanol for 10 minutes is 20% or less.
Characteristic B: When the silicon-modified polyurethane resin is a film having a thickness of 50 μm and a width of 2.5 cm, the 100% modulus of the film is 10 MPa or more.

[2] including a coating step of applying the silicone-modified polyurethane resin having the above characteristics A and B in a dot shape on the surface of the silver surface layer containing the colorant, It is a manufacturing method of the leather-like sheet which makes the average shortest distance between the dots nearest to a dot 10-100 micrometers.

  ADVANTAGE OF THE INVENTION According to this invention, even if it contacts alcohol, it is hard to discolor and can provide the leather-like sheet | seat which can maintain a flexibility favorably, and its manufacturing method.

  The leather-like sheet (artificial leather) of the present invention has a silver surface layer, and a silicon-modified polyurethane resin having characteristics A and B described later is applied in the form of dots (dots) on the silver surface layer. . The average shortest distance between one dot and the other dots closest thereto is 10 to 100 μm.

  The silicon-modified polyurethane resin is in the form of dots and has a good flexibility by being applied so that the average shortest distance between one dot and the other dots closest thereto is 10 to 100 μm. Can be maintained. As a result, a leather-like sheet having an excellent texture can be obtained. Moreover, when alcohol adheres, there exists a tendency for a polyurethane resin to swell moderately and to close the gap | interval of a dot, and color fading by alcohol can be prevented.

The “average” of the “average shortest distance” means an average of arbitrary five shortest distances. The average shortest distance refers to the average value of the five shortest distances obtained by performing scanning electron microscope imaging, measuring the shortest distance among adjacent five dots. The shortest distance is not the distance from the center of a dot, but the shortest distance between the outer periphery of a dot and the outer periphery of a dot adjacent to the dot. It can be determined as described in the examples described later.
In addition, although an average shortest distance is 10-100 micrometers, it is preferable that it is 20-60 micrometers.

Further, the occupied area ratio of dots is preferably 50 to 90%, and more preferably 70 to 80%. By setting the content to 50 to 90%, even if alcohol comes into contact without impairing the texture and bending resistance, color fading is difficult.
The occupation area ratio can be obtained from, for example, a total area of dots existing in a 1 mm × 1 mm region in the center by photographing the surface portion of the silver surface layer of the leather-like sheet with an electron microscope.
Furthermore, it is preferable that the circle equivalent average diameter of a dot is 100-300 micrometers, and it is more preferable that it is 150-250 micrometers.

The characteristics that the silicon-modified polyurethane resin according to the present invention should have are as follows.
Characteristic A: The silicon-modified polyurethane resin is formed into a film having a thickness of 50 μm and a 10 cm square, and the swelling ratio after being immersed in 99.5% ethanol for 10 minutes is 20% or less. When the swelling rate exceeds 20%, the alcohol resistance tends to be lowered, and when the alcohol comes into contact with the alcohol, color fading may occur and the polyurethane resin layer constituting the surface may be deformed or dropped. Here, the swelling rate is an area swelling rate and can be determined as described in the examples described later.
The swelling rate is preferably -5 to 20%, and more preferably 5 to 15%.

Characteristic B: When the silicon-modified polyurethane resin is formed into a film having a thickness of 50 μm and a width of 2.5 cm, the 100% modulus of the film is 10 MPa or more. When the 100% modulus is less than 10 MPa, the solvent resistance and mechanical properties of the polyurethane resin are lowered, wear resistance is lowered, and color fading occurs when it comes into contact with alcohol. Here, the 100% modulus can be obtained as described in Examples described later.
The 100% modulus is preferably 10 to 20 MPa, and more preferably 12 to 18 MPa.

The silicon-modified polyurethane resin having the above characteristics A and B can be obtained by a conventionally known method such as introducing an organopolysiloxyl group into a molecular side chain or terminal.
For example, in order to set the swelling ratio to a desired value, it is possible to adopt a known method for improving the solvent resistance of polyurethane, and appropriately change the hard segment, the type of diol, and nitrogen% as the composition of the polyurethane. Thus, a desired value can be obtained. It is also possible to add a crosslinking agent or the like. In order to obtain a desired value of 100% modulus, the polyurethane can be easily adjusted by a known method. For example, a polymer diol having a number average molecular weight of 500 to 2500, such as a polyester diol, a polyether At least one polymer diol selected from diol, polyester / ether diol, polycaprolactone diol, polycarbonate diol, etc., and at least one selected from the group of aromatic diisocyanate, alicyclic diisocyanate, aliphatic diisocyanate, etc. A low molecular weight compound having at least two active hydrogen atoms, for example, a low molecular weight diol, a low molecular weight diamine, a low molecular weight compound containing active hydrogen atoms such as hydrazine and dicarboxylic acid dihydrazide, as a chain extender. The reaction may be performed at a molar ratio such that the 100% modulus is 10 MPa or more.

The silver surface layer according to the present invention contains a colorant and has colors such as red, yellow, green, and blue. The colorant is not particularly limited, and examples thereof include known chromatic pigments and white pigments.
“Chromatic color” means a color having a hue, such as red, orange, yellow, green, blue, blue-violet, purple, magenta, and their intermediate colors. Not included.

The silver surface layer according to the present invention is formed on the surface of a fibrous base material, for example.
As the fibrous base material, a knitted fabric, a nonwoven fabric or a fiber entangled body (three-dimensional entangled nonwoven fabric) is preferably used. The fibrous base material is preferably impregnated with a polymer elastic body. A fibrous base material having a fiber entangled body impregnated with a polymer elastic body and a coating layer formed on the surface thereof is more preferably used. In particular, it is preferable that a sponge-like (porous) polymer elastic body is contained inside the three-dimensional entangled nonwoven fabric (fiber entangled body). When it is sponge-like, the touch and texture of the leather-like sheet surface become flexible.

  The fibers constituting the knitted fabric, the nonwoven fabric, and the fiber entangled body are selected from conventionally known natural fibers, synthetic fibers, and semi-synthetic fibers. Industrially known cellulose fibers, acrylic fibers, polyester fibers, polyamide fibers and the like are preferably used alone or in admixture of two or more in view of quality stability and price. In the present invention, although not particularly limited, an ultrafine fiber capable of realizing a soft texture closer to natural leather is preferable, and the average fineness is preferably 0.0001 to 0.3 dtex, more preferably 0.0001 to Extra fine fibers of 0.1 dtex are preferably used.

  As a method for obtaining such an ultrafine fiber, (a) a method of directly spinning an ultrafine fiber having a target average fineness, and (b) a fine fiber-generating fiber that is once thicker than the target fineness is spun, and then the target And a method of transforming into ultrafine fibers having an average fineness of Since handling of ultrafine fibers is often difficult, the method (b) in which ultrafine fiber-generating fibers are transformed into ultrafine fibers in the latter half of the production process is preferred.

  In the method (b), two or more types of thermoplastic polymers that are not compatible are combined or spun to obtain ultrafine fiber-generating fibers, and at least one polymer component is extracted from the ultrafine fiber-generating fibers. It is common to transform into ultrafine fibers by removing or decomposing, or by separating and peeling the polymer at the interface of the polymer components. Examples of the ultrafine fiber-generating fiber containing a removable polymer component include sea-island fiber and multilayer laminated fiber. In the case of sea island type fibers, the sea component polymer is extracted or removed by decomposition, and in the case of multilayer laminated type fibers, at least one of the laminated polymer components is extracted and removed or decomposed to remove island components (non- An ultrafine fiber bundle composed of the removed polymer component) is obtained. The solvent used for extraction or decomposition / removal may be any solvent that does not dissolve the island component (non-removed polymer component) but dissolves the sea component polymer, and practically includes water and toluene. In addition, examples of the ultrafine fiber-generating fiber that is separated at the interface of the polymer component include petal-like laminated fiber and multilayer laminated fiber, and the like, between different polymer components to be laminated by physical treatment or chemical treatment. An ultrafine fiber bundle can be obtained by peeling each other at the interface.

  The island component polymer of the sea-island fiber or multilayer laminated fiber is a polymer that can be melt-spun and has sufficient fiber properties such as strength, and has a higher melt viscosity than the sea-component polymer and a surface tension under the spinning conditions. Larger polymers are preferred. Examples of such island component polymers include polyamides such as nylon-6, nylon-66, nylon-610, and nylon-612 and copolymers based on these, or polyethylene terephthalate, polypropylene terephthalate, polytrimethylene terephthalate. Polyesters such as polybutylene terephthalate and copolymers mainly composed thereof are preferably used.

  As the sea component polymer of the sea-island fiber or the multilayer laminated fiber, the melt viscosity is lower than that of the island component polymer, and the solubility in the solvent or the decomposability by the decomposing agent is larger than that of the island component polymer, polyethylene, modified polyethylene, polypropylene, Polystyrene, modified polystyrene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, styrene-ethylene copolymer, styrene-acrylic copolymer, modified polyester, polyvinyl alcohol resin and the like are preferably used. The use of water-soluble thermoplastic polyvinyl alcohol (water-soluble PVA) for the sea component polymer is particularly preferred because a silvered leather-like sheet can be produced without using an organic solvent.

The water-soluble PVA has a viscosity average polymerization degree (hereinafter simply referred to as a polymerization degree) of preferably 200 to 500, more preferably 230 to 470, and further preferably 250 to 450. When the degree of polymerization is 200 or more, the melt viscosity is moderate and it is easy to combine with the island component polymer. When the degree of polymerization is 500 or less, it is possible to avoid a problem that it is difficult to discharge the resin from the spinning nozzle because the melt viscosity is too high. By using so-called low polymerization degree PVA having a polymerization degree of 500 or less, there is also an advantage that the dissolution rate is increased when dissolving with hot water. The degree of polymerization (P) of the water-soluble PVA is measured according to JIS-K6726. That is, after re-saponifying and purifying water-soluble PVA, it is obtained from the intrinsic viscosity [η] measured in water at 30 ° C. by the following equation.
P = ([η] 10 ³ /8.29) ^{(1 / 0.62)}

  The saponification degree of the water-soluble PVA is preferably 90 to 99.99 mol%, more preferably 93 to 99.98 mol%, further preferably 94 to 99.97 mol%, and particularly preferably 96 to 99.96 mol%. . When the degree of saponification is 90 mol% or more, thermal stability is good, satisfactory melt spinning can be performed without thermal decomposition or gelation, and biodegradability is also good. Further, the water-solubility is not lowered by the copolymerization monomer described later, and it becomes easy to make it ultrafine. Water-soluble PVA having a degree of saponification of greater than 99.99 mol% is difficult to produce stably.

  160-230 degreeC is preferable, as for melting | fusing point (Tm) of water-soluble PVA, 170-227 degreeC is more preferable, 175-224 degreeC is further more preferable, 180-220 degreeC is especially preferable. When the melting point is 160 ° C. or higher, the crystallinity is not lowered and the fiber strength is not lowered, and it is also possible to prevent the fiber from becoming difficult due to poor thermal stability. When the melting point is 230 ° C. or lower, melt spinning can be performed at a temperature lower than the decomposition temperature of PVA, and sea-island long fibers can be stably produced.

  The water-soluble PVA can be obtained by saponifying a resin mainly containing vinyl ester units. Vinyl compound monomers for forming vinyl ester units include vinyl formate, vinyl acetate, vinyl propionate, vinyl valenate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate and Examples include vinyl versatate, and among these, vinyl acetate is preferable from the viewpoint of easily obtaining water-soluble PVA.

  The water-soluble PVA may be a homo-PVA or a modified PVA into which copolymer units are introduced, but it is preferable to use a modified PVA from the viewpoint of melt spinnability, water-solubility and fiber properties. Examples of the comonomer include α-olefins having 4 or less carbon atoms such as ethylene, propylene, 1-butene, and isobutene, methyl vinyl ether, and ethyl vinyl ether from the viewpoints of copolymerizability, melt spinnability, and water solubility of the fiber. , Vinyl ethers such as n-propyl vinyl ether, isopropyl vinyl ether and n-butyl vinyl ether are preferred. The amount of units derived from α-olefins having 4 or less carbon atoms and / or vinyl ethers is preferably 1 to 20 mol%, more preferably 4 to 15 mol%, and more preferably 6 to 13 mol% of the modified PVA structural unit. Further preferred. Further, when the comonomer is ethylene, the fiber physical properties are improved, and therefore modified PVA containing ethylene units preferably in an amount of 4 to 15 mol%, more preferably 6 to 13 mol% is preferable.

  The water-soluble PVA is produced by a known method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method. Among these, a bulk polymerization method or a solution polymerization method in which polymerization is performed without solvent or in a solvent such as alcohol is preferable. Examples of the solvent for the solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol. Examples of the initiator used for copolymerization include a, a′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethyl-valeronitrile), benzoyl peroxide, and n-propyl peroxycarbonate. And known initiators such as azo initiators or peroxide initiators. Although there is no restriction | limiting in particular about superposition | polymerization temperature, The range of 0-150 degreeC is suitable.

  The preferred sea-island volume ratio of the ultra-fine fiber-generating fiber, that is, the sea-island type fiber that suitably generates ultra-fine fibers having a fineness of 0.3 dtex or less is in the range of sea / island = 30/70 to 70/30, preferably 40 / 60 to 60/40. If the sea component is 30% or more, the amount of the component dissolved or decomposed and removed with a solvent or a decomposing agent is sufficient, so that the flexibility of the obtained leather-like sheet can be sufficiently expressed. Therefore, measures such as excessive use of treatment agents such as softeners are not required. Use of an excessive amount of the treatment agent is not preferable because it causes problems such as deterioration in mechanical properties such as tear strength, influence on other treatment agents, influence on touch, and deterioration in durability. Moreover, if the sea component is 70% or less, the absolute amount of fibers composed of island components after dissolution or decomposition is sufficient, and thus the obtained leather-like sheet has sufficient mechanical properties. In addition, because there are not too many components to dissolve or decompose and remove, there is no problem of quality variation due to defective removal or processing of a large amount of removed components. It is also suitable from the industrial viewpoint. The ultrafine fiber generating fiber (sea-island fiber) is melt-spun by extruding a sea component polymer and an island component polymer from a composite spinning die. The spinning temperature (die temperature) is preferably 180 to 350 ° C. The average fineness of the ultrafine fiber generating fiber is preferably 1 to 10 dtex, and the number of islands in the cross section of the fiber is preferably 10 to 10,000.

  In the production of conventional artificial leather and the like, a fiber web was produced from staples obtained by cutting ultrafine fiber-generating long fibers into an arbitrary fiber length, but in the present invention, a sea island spun by a spunbond method or the like. The long mold fibers (ultrafine fiber generating long fibers) may be used without being cut. Accordingly, in the present invention, a fiber web can be produced by a conventionally known method such as a card method, a papermaking method, a spunbond method, etc., using ultrafine fiber-generating short fibers or ultrafine fiber-generating long fibers.

Next, the fiber web is entangled to produce a fiber entangled body (three-dimensional entangled nonwoven fabric). As the entanglement method, conventionally known methods such as a needle punch method and a spunlace method can be used alone or in combination. A particularly preferable method is that after the ultrafine fiber-generating long fibers obtained by spinning are stretched to about 1.5 to 5 times, mechanical crimps are applied, and the fibers are cut to a length of about 3 to 7 cm to obtain short fibers. Later, this is defibrated with a card to form a fibrous web of a desired density through a webber, the resulting fibrous web is laminated to a desired weight, and then a needle with one or more barbs is used In this method, the fibers are entangled in the thickness direction by needle punching at about 300 to 4000 punch / cm ² . The basis weight of the fiber entangled body may be adjusted in accordance with the basis weight of the product, but is preferably 200 to 1000 g / m ² in terms of subsequent process passability and workability.

  Subsequently, the obtained fiber entangled body is subjected to a known method such as a dip nip method, a knife coating method, a bar coating method, a roll coating method, a spray coating method, or the like as necessary. Next, the polymer elastic body is solidified so as to form a large number of voids in a sponge form by a dry method or a wet method. As the polymer that can be used, any known polymer generally used in the production of leather-like sheets can be used. For example, polyurethane-based resins, polyester-based elastomers, rubber-based polymers can be used. Suitable examples include resins, polyvinyl chloride resins, polyacrylic acid resins, polyamino acid resins, silicon resins, and modified products, copolymers, or mixtures thereof.

  The polymer elastic body is preferably impregnated into the fiber entangled body as an aqueous dispersion or an organic solvent solution. When an aqueous dispersion is used, it is gelled and solidified mainly by a dry method (50 to 150 ° C.), and when an organic solvent solution is used, the polymer elastic body is solidified in a sponge form mainly by a wet method. In the wet coagulation, the fiber entangled body impregnated with the organic solvent solution is immersed in a treatment bath containing a poor solvent for the polymer elastic body to solidify the polymer elastic body into a porous state. As a poor solvent for the polymer elastic body, water is preferably used, but when a treatment bath in which a good solvent for the polymer elastic body such as dimethylformamide is mixed with water is used, a solidification state is obtained by appropriately setting the mixing ratio. That is, it is preferable because the porous state and shape can be controlled. When using an aqueous dispersion, adding a heat-sensitive gelling agent allows solidification more uniformly in the thickness direction by combining a dry method or a method such as steaming or far-infrared heating. . When an organic solvent is used, more uniform voids can be obtained by using a coagulation modifier together. Examples of the organic solvent include dimethylformamide, dimethylacetamide, dimethyl sulfoxide and the like. A texture similar to that of natural leather can be obtained by solidifying a fiber entangled body, in particular, a polymer polymer impregnated in a three-dimensional entangled nonwoven fabric into a sponge.

  In the present invention, a polyurethane-based resin is preferably used as the polymer elastic body from the viewpoint of the texture of the composite (fibrous substrate) composed of the ultrafine fiber entangled body and the polymer elastic body and the balance of physical properties. Examples of the polyurethane resin include various types obtained by reacting at least one polymer diol having an average molecular weight of 500 to 3000, at least one organic diisocyanate, and at least one chain extender in a predetermined molar ratio. Of polyurethane. Examples of the polymer diol include polyester diol, polyether diol, polyester ether diol, polylactone diol, and polycarbonate diol. Examples of the organic diisocyanate include aromatic and alicyclic groups such as tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. And aliphatic organic diisocyanates. Examples of the chain extender include low molecular compounds having at least two active hydrogen atoms such as diol, diamine, hydroxyamine, hydrazine, hydrazide. If necessary, the polyurethane may be a mixture of a plurality of types of polyurethane, or a polymer composition obtained by adding a polymer such as synthetic rubber, polyester elastomer, or polyvinyl chloride.

  When using the above-mentioned ultrafine fiber generating fiber, after impregnating and coagulating a polymer elastic body solution or dispersion, or before impregnating and coagulating, ultrafine fiber generation treatment is performed. Transform fibers into ultrafine fiber bundles. When the ultrafine fiber treatment is carried out after solidifying the polymer elastic body, especially if it is a sea-island type fiber, the sea component polymer is removed and a void is generated between the ultrafine fiber bundle and the polymer elastic body, Since the restraint of the ultrafine fiber bundle by the polymer elastic body becomes weak, the texture of the obtained leather-like sheet becomes softer, and this method is preferably employed in the present invention. On the other hand, when the ultrafine fiber treatment is performed before impregnating and solidifying the polymer elastic body, the ultrafine fiber bundle is strongly restrained by the polymer elastic body, and thus the texture of the obtained leather-like sheet tends to be harder There is. However, when the ratio of the polymer elastic body in the fiber entangled body is decreased, the tendency to become hard can be sufficiently suppressed, and the ratio of fibers is higher and the purpose is to achieve a solid texture with a sense of fulfillment. Is a preferred method. The average fineness of the fiber bundle of ultrafine fibers is preferably 1 to 10 dtex.

The thickness of the fibrous base material used in the present invention can be arbitrarily selected according to the intended use and texture, and is not particularly limited, but is preferably 0.4 to 3.0 mm.
Further, the mass ratio between the ultrafine fibers and the polymer elastic body in the fibrous base material may be appropriately selected according to the required physical properties and texture, and is not an essential feature for obtaining the effects of the present invention. Usually, it is 35/65 to 90/10.

  As a method for forming a silver surface layer containing a colorant (hereinafter sometimes simply referred to as “silver surface layer”) on the surface of the fibrous base material, various conventionally known methods can be employed singly or in combination. . For example, when preparing a coating liquid such as a pigment and a polymer elastic body as a coating liquid, and using a coater such as a knife, a bar, or a roll, first supply an excessive amount of the coating liquid onto the fibrous base material, Examples include a method in which only a quantity measured with a certain clearance set between the base material and the coater is applied to the surface of the base material and solidified and solidified by a dry method or a wet method, and a gravure roll coater or a comma coater. -When using a spray coater etc., the method of apply | coating the required amount of coating liquid measured beforehand to the base-material surface, and solidifying and solidifying similarly by a dry method or a wet method is mentioned. The silver surface layer does not necessarily need to be porous, but may be solidified into a porous state by a wet method if necessary. When the fibrous base material is a composite composed of a fiber entangled body and a polymer elastic body, the solidification of the polymer elastic body impregnated into the fibrous base material and the solidification of the polymer elastic body forming a silver surface layer If the method of completing simultaneously is employ | adopted, drying after coagulation can be completed in one time, and also in the obtained leather-like sheet, it is easy to obtain a sense of unity between the fibrous base material and the silver surface layer.

  As another method for forming a silver surface layer on the surface of a fibrous base material, a dispersion of a pigment and a polymer elastic body is prepared as a coating liquid, and the knife described above is applied to a transfer release sheet such as a film or a release paper. Apply a predetermined amount of coating liquid while measuring with a coater, etc., and solidify the polymer elastic body into a film or porous state by the same dry method or wet method as above, and dry and solidify it. After that, the substrate is bonded to the fibrous base material with an adhesive, or bonded with a polymer elastic body re-dissolved using a treatment liquid containing a solvent for the polymer elastic body. Examples include a method of pasting and integrating with a material, a method of pasting to a substrate before the coating liquid on the release transfer sheet is solidified and solidified, and then peeling the release transfer sheet to the surface of the release transfer sheet. The irregular pattern and mirror surface that were shaped are transferred. Silver surface was obtained (transfer peeling method).

  As the polymer elastic body forming the silver surface layer, for example, synthetic rubber, polyester elastomer, polyvinyl chloride resin, polyurethane resin and the like can be used. Among these, from the viewpoint of balance such as elasticity, softness, and abrasion resistance, a polyurethane-based resin is preferably used in the same manner as the polymer elastic body contained in the fiber entangled body.

  The polyurethane resin for forming the silver layer is selected from the same resins as the polyurethane resin to be contained in the fiber entangled body. If necessary, a mixture of a plurality of types of polyurethane-based resins may be used, and a polymer composition mainly composed of polyurethane may be used by adding a polymer such as synthetic rubber, polyester elastomer, or polyvinyl chloride. You can also. From the standpoint of hydrolysis resistance and elasticity, a polyurethane resin in which the polymer diol component is a polyether polymer diol such as polytetramethylene glycol is preferred.

  Additives such as a light-resistant agent and a dispersant are added to the dispersion liquid of the pigment and the polymer elastic body applied onto the fibrous base material, depending on the purpose, alone or in combination. As other additives, in order to control the porous shape, in addition to the foaming agent in the case of dry foaming, a coagulation regulator in the case of wet coagulation is selected as necessary, alone or several Combinations of seeds may be added.

  As a method of forming a silver surface layer on the surface of a fibrous base material, in addition to the above-described method of applying a dispersion containing a pigment and a polymer elastic body, and a transfer peeling method using the dispersion, a polymer elastic body There is a method in which after forming a coating layer made of the above, another coating liquid containing a pigment and a polymer elastic body is applied to the surface of the coating layer to further form a surface layer made of the pigment and the polymer elastic body.

  When the silver surface layer is only a layer (surface layer) containing a pigment and a polymer elastic body, the thickness of the silver surface layer can be arbitrarily selected according to the intended use and texture, and is particularly limited However, it is preferably 0.05 to 1 mm. If the thickness of the silver surface layer is 0.05 mm or more, the minimum necessary mechanical properties such as wear resistance can be secured, which is preferable. On the other hand, if the thickness of the silver layer is 1 mm or less, the weight can be reduced.

  When the silver layer is composed of a surface layer containing a pigment and a polymer elastic body and a coating layer made of a polymer elastic body not containing a pigment, the thickness of the surface layer is preferably 0.01 to 0.8 mm, More preferably, it is 0.03-0.5 mm, The thickness of a coating layer becomes like this. Preferably it is 0.001-0.5 mm, More preferably, it is 0.01-0.3 mm. The total thickness of the surface layer and the coating layer is preferably 0.05 to 1 mm, more preferably 0.1 to 0.8 mm. Here, even if a coating layer is formed on the surface layer, suppression of color fading due to contact of alcohol with the coating layer is not sufficient, and in order to suppress color fading, the characteristics A and B of the present invention are combined. It is necessary to apply a silicone-modified polyurethane resin in the form of dots.

  In addition to the absolute requirements that come from the above-mentioned uses, the balance between the thickness of the fibrous base material and the thickness of the entire leather-like sheet is also an important factor that determines the preferred thickness of the silver layer. From experience, the ratio of the thickness of the silver surface layer to the fibrous base material is preferably in the range of 0.01: 99.9 to 60:40. If the ratio of the silver layer is greater than 0.01, the presence of the silver layer is sufficiently felt in the texture, and if it is less than 60, a so-called rubber-like leather-like sheet mainly composed of the silver layer in the texture. Can be avoided.

After forming the silver surface layer, the silicon-modified polyurethane resin having the above-described characteristics A and B is applied in the form of dots on the surface of the silver surface layer containing the color pigment (application process).
In the coating step, the average shortest distance between the dots when the dots are coated and the dots closest to the dots is set to 10 to 100 μm. Examples of the method of applying in the form of dots include spray coating and gravure coating, but considering the ease of control of productivity, dot spacing, and dot diameter, the silicon-modified polyurethane having the aforementioned characteristics A and B It is preferable to apply gravure coating from the viewpoint that the average shortest distance can be suitably controlled by the adhesion state of the resin and the gravure roll mesh. The adhesion amount of the silicone-modified polyurethane having the above-described characteristics A and B is preferably in the range of 1 to 10 g / m ² from the viewpoint of easily preventing discoloration.
In addition, as long as the effect of this invention is not impaired, you may provide desired resin to the surface by which the silicone modified polyurethane resin which has the above-mentioned characteristic A and B was apply | coated to the dot form.

The leather-like sheet of the present invention as described above is suitable for carrying a bag, a mobile phone case top, a vehicle interior, a handle cover, an interior, and the like.
In particular, the leather-like sheet is suitable for a shoulder bag, and examples of the shoulder bag include a school bag. For example, when the leather-like sheet is used for a school bag, it is extremely suitable as a surface material for a cover portion called a crown portion, and further, a lateral portion (thickness portion) called a heel portion, a shoulder strap It is also suitable for the front part and the front part (the front part of the school bag that appears when the crown is lifted).

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. Unless otherwise specified, “parts” in Examples and Comparative Examples means “parts by mass”.

Evaluation and measurement performed in Examples and Comparative Examples are as follows.
(1) Discoloration evaluation by alcohol:
Using a clocking meter, the gauze immersed in 99.5% ethanol was reciprocated 100 times, and the color of the gauze was determined using a gray scale (for contamination). The higher the grade, the less color fading.
(2) Evaluation of flexibility:
Using a Bally Flexometer, it was repeatedly bent at room temperature (20 ° C., 65% RH), and the number of times until a crack occurred was measured. If it is 300,000 times or more, it can be said that good flexibility is maintained.
(3) Measurement of alcohol swelling ratio of the film when the polyurethane resin applied on the silver surface layer is a film:
A film with a thickness of 50 μm was prepared, a 10 cm square sample was immersed in 99.5% ethanol, and the area swelling rate after 10 minutes was measured. The area swelling rate was determined from “area of sample after immersion / area of sample before immersion (= 10 cm × 10 cm) × 100”.
(4) Measurement of 100% modulus of the film when the polyurethane resin applied on the silver surface layer is a film:
A film having a thickness of 50 μm was prepared on a flat release paper, and a portion having no thickness unevenness was cut into a 2.5 cm width and a length of 100 mm to obtain a sample. It was measured by an autograph and obtained from the stress when the film was stretched 100%.
(5) Measurement of occupation area ratio:
The area occupied by the dots was determined from the total area of the dots present in a 1 mm × 1 mm region in the center by photographing the surface portion of the silver layer of the leather-like sheet with an electron microscope (SEM).

Example 1
A sea-island composite fiber consisting of 45 parts of 6-nylon (sea component) and 55 parts of polystyrene (island component) was obtained by melt spinning. This was stretched 3 times, a fiber oil agent was applied, and after mechanical crimping, it was dried. The obtained crimped fiber was cut into 51 mm to form a 3 dtex staple, and then a web was formed, and needle punching of about 500 punch / cm ² was performed alternately from both sides to obtain an entangled nonwoven fabric.

The basis weight of this entangled nonwoven fabric was 350 g / m ² and the apparent specific gravity was 0.17. This entangled nonwoven fabric was treated with a 4% aqueous solution of polyvinyl alcohol, the thickness was compressed and fixed to about 1.3 mm, and the surface was smoothed by buffing. This was impregnated with a dimethylformamide (hereinafter referred to as DMF) solution of polyurethane mainly composed of 13% concentration polyester-based polyurethane. Further, the same polyurethane elastomer solution was applied to the surface in an amount of 100 g / m ² as a solid content, and then the polyurethane was wet-coagulated in a porous state by dipping in a DMF / water mixture, and then heated in hot toluene. The composite component was converted into a hollow fiber by eluting and removing the island component, and a fibrous base material provided with a polyurethane porous layer was obtained.

  On release paper (DE-125 manufactured by Dai Nippon Printing Co., Ltd.), 100 parts by mass of a non-yellowing polycarbonate polyurethane solution (resin content 25%), 20 parts by mass of Rezamin DUT Red (manufactured by Dainichi Seika Kogyo Co., Ltd.), A solution containing 30 parts by mass of DMF and 30 parts by mass of methyl ethyl ketone was applied so that the thickness after drying was 15 μm, and dried to form a polyurethane outermost layer serving as the outermost layer of the silver surface layer.

  On the obtained polyurethane outermost layer, a DMF solution containing 100 parts by mass of a one-component polyether polyurethane (Resamine ME8116 manufactured by Dainichi Seika Kogyo Co., Ltd.) and 20 parts by mass of Resamine DUT Red is dried to a thickness of 20 μm. This was applied and dried to form a polyurethane intermediate layer.

Furthermore, on the intermediate layer, 100 parts by mass of a crosslinkable polyurethane adhesive solution composition UD8310 (Daiichi Seika Kogyo Co., Ltd.), 10 parts by mass of D-110N (manufactured by Takeda Pharmaceutical Co., Ltd.), 5 parts by mass of DMF, ethyl acetate A polyurethane adhesive solution consisting of 10 parts by mass is coated with 240 g / m ² (pure content 130 g / m ² ), dried at 70 ° C. for 15 seconds, and the solvent is partially evaporated on the fibrous base material. The polyurethane porous layer was pasted. Then, after pressing with a roll with a clearance of 65% of the total thickness of the polyurethane porous layer and the fiber substrate, dried at 130 ° C. for 3 minutes, aged at 50 ° C. for 3 days, and then released from the release paper. The leather-like sheet in which the polyurethane porous layer and the silver surface layer were formed on the fibrous base material was peeled off.

Further, on the surface of the leather-like sheet, a silicon-modified hardly yellowing polyester polyurethane having a 100% modulus of 19 MPa (Rezaroid SP-215 manufactured by Dainichi Seika Kogyo Co., Ltd.) is used in a solid content of 2 g using a 150 mesh gravure roll. / M ² was applied (application process) to prepare a leather-like sheet suitable for the satchel cover material sheet.

(Example 2)
Supply with pressure balance so that the average area ratio of 25 parts of ethylene-modified polyvinyl alcohol (sea component) and 75 parts of polyethylene terephthalate (island component) is sea component / island component = 25/75. It was discharged. The air-jet / nozzle-type suction device, whose airflow pressure is adjusted so that the average spinning speed is 3600 m / min, is pulled and thinned, and the sea island-type fiber with an average fineness of 2.4 dtex is spun and sucked from the back side. While collecting continuously on the net, a long fiber web having a basis weight of 30 g / m ² was obtained.

  After the embossed long fiber web surface is sprayed with an oil agent composed mainly of a mineral oil-based slipping oil and mixed with an antistatic agent, the long fiber web is continuously folded using a cross-wrapper device and layered. The long fiber web was subjected to a three-dimensional entanglement process by a needle punch method to obtain a nonwoven fabric structure. Next, after uniformly spraying water on both surfaces of this nonwoven fabric structure, it was immediately passed through an atmosphere having a temperature of 75 ° C. and a relative humidity of 95% to perform wet heat shrinkage treatment, and then between metal rolls kept at 120 ° C. It was dried while being pressed and smoothed by pressing.

  The nonwoven fabric structure after drying was impregnated with an aqueous dispersion of a polyurethane composition mainly composed of polycarbonate-based polyurethane (solid content concentration 20%), pressed, and heat-coagulated. Next, the non-woven fabric made of ultra-fine long fiber bundles of modified polyethylene terephthalate is treated with hot water at 90 ° C. for 20 minutes in a liquid dyeing machine to extract and remove the modified polyvinyl alcohol in the sea-island fibers and then dried. A fibrous base material having a thickness of about 0.8 mm in which a polyurethane composition was contained inside the structure was obtained. Further, the back surface was buffed to adjust the thickness to 0.6 mm.

A silver surface layer was formed on this fibrous base material in the same manner as in Example 1 to obtain a leather-like sheet. Further, on the surface of the leather-like sheet, a silicon-modified non-yellowing polycarbonate / polyether polyurethane having a 100% modulus of 13 MPa (Resaloid SP-300 manufactured by Dainichi Seika Kogyo Co., Ltd.) is solidified using a 150 mesh gravure roll. It was applied so as to be 3 g / m ² per minute (application process), and a leather-like sheet suitable for the upper cover of a mobile phone case was produced.

(Comparative Example 1)
A leather-like sheet was produced in the same manner as in Example 1 except that a silicon-modified non-yellowing polyether polyurethane having a 100% modulus of 5 MPa was used.

(Comparative Example 2)
A leather-like sheet was prepared in the same manner as in Example 1 except that a polyurethane resin having a 100% modulus of 11 MPa that was not modified with silicon was used instead of the silicone-modified polyurethane.

(Comparative Example 3)
After drying a solution containing silicon-modified hard yellowing polyester polyurethane having a 100% modulus of 19 MPa (Resaloid SP-215 manufactured by Dainichi Seika Kogyo Co., Ltd.) on release paper (DE-125 manufactured by Dai Nippon Printing Co., Ltd.) It was applied so as to cover the entire surface so that the thickness of the polyurethane layer was 5 μm, and dried to form a polyurethane outermost layer that became the outermost layer of the silver surface layer. Subsequently, a solution containing 100 parts by mass of a non-yellowing polycarbonate polyurethane solution (resin content 25%), 20 parts by mass of Rezamin DUT Red (manufactured by Dainichi Seika Kogyo Co., Ltd.), 30 parts by mass of DMF, and 30 parts by mass of methyl ethyl ketone is dried. It was applied so as to have a later thickness of 15 μm and dried to form a polyurethane layer.

  On the obtained polyurethane layer, a DMF solution containing 100 parts by mass of one-component polyether polyurethane (Resamine ME8116 manufactured by Dainichi Seika Kogyo Co., Ltd.) and 20 parts by mass of Resamine DUT Red has a thickness after drying of 20 μm. And dried to form a polyurethane interlayer.

Furthermore, on the intermediate layer, 100 parts by mass of a crosslinking polyurethane adhesive UD8310 (manufactured by Dainichi Seika Kogyo Co., Ltd.), 10 parts by mass of D-110N (manufactured by Takeda Pharmaceutical Co., Ltd.), 5 parts by mass of DMF, and 10 parts by mass of ethyl acetate. The polyurethane base adhesive solution consisting of 240 g / m ² (pure content 130 g / m ² ) was applied, dried at 70 ° C. for 15 seconds, and the solvent was partially evaporated. The polyurethane porous layer on the material was pasted. Then, after pressing with a roll with a clearance of 65% of the total thickness of the polyurethane porous layer and the fiber substrate, dried at 130 ° C. for 3 minutes, aged at 50 ° C. for 3 days, and then released from the release paper. The leather-like sheet in which the polyurethane porous layer and the silver surface layer were formed on the fibrous base material was peeled off.

(Comparative Example 4)
A leather-like sheet was produced in the same manner as in Example 1 except that a mesh gravure roll having an average distance between dots of 150 μm was used.

  From Table 1, it was confirmed that the leather-like sheets of Examples 1 and 2 were less likely to lose color and maintained good flexibility.

Claims (4)

Having a silver layer containing a colorant;
A silicon-modified polyurethane resin having the following characteristics (A) and (B) is applied in the form of dots on the surface of the silver surface layer, and the average shortest distance between one dot and another dot closest to the dot A leather-like sheet having a thickness of 10 to 100 μm.
Characteristic (A): The silicon-modified polyurethane resin is formed into a film having a thickness of 50 μm and a 10 cm square, and the swelling ratio after being immersed in 99.5% ethanol for 10 minutes is 20% or less.
Characteristic (B): When the silicon-modified polyurethane resin is a film having a thickness of 50 μm and a width of 2.5 cm, the 100% modulus of the film is 10 MPa or more.   The leather-like sheet according to claim 1, wherein an area ratio of the dots is 50 to 90%. Including a coating step of applying a silicone-modified polyurethane resin having the following characteristics (A) and (B) in a dot shape on the surface of the silver surface layer containing the color pigment,
The manufacturing method of the leather-like sheet | seat which makes the average shortest distance between the dot at the time of apply | coating in the shape of a dot at the said application | coating process and the dot nearest to this dot 10-100 micrometers.
Characteristic (A): The silicon-modified polyurethane resin is formed into a film having a thickness of 50 μm and a 10 cm square, and the swelling ratio after being immersed in 99.5% ethanol for 10 minutes is 20% or less.
Characteristic (B): When the silicon-modified polyurethane resin is a film having a thickness of 50 μm and a width of 2.5 cm, the 100% modulus of the film is 10 MPa or more.   The method for producing a leather-like sheet according to claim 3, wherein the method of applying the dots is gravure application.