JP2004250809A - Leather-like sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a leather-like sheet which has a graceful appearance, a soft surface touch and a balanced hand giving a good sense of fulfillment, similar to those of natural leathers. <P>SOLUTION: This leather-like sheet comprising a fibrous substrate layer prepared by charging and filling an elastic resin consisting mainly of a polyurethane into the interlacing spaces of a three-dimensional interlaced nonwoven fabric, a surface porous layer adhered to the surface of the fibrous substrate layer, and a surface finishing layer, is characterized in that the surface porous layer comprises a polyurethane resin A having a 100% modulus of (a) and that a polyurethane resin B having a 100% modulus of (b) and a polyurethane resin C having a 100 % modulus of (c) are respectively charged into the upper layer portion and the lower layer portion of the fibrous substrate layer, adhered to the surface of the fibrous substrate layer, wherein an expression (1): 20<(a)-(b) and an expression (2): 20<(b)-(c) are satisfied. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a leather-like sheet having a natural leather-like elegant appearance, a fine surface texture, and a well-balanced soft texture that gradually changes from hard to soft from the surface layer, and is widely used in applications such as shoes and bags. Leather-like sheet that can be made.
[0002]
[Prior art]
2. Description of the Related Art In recent years, synthetic leather and artificial leather have been widely used in various fields such as shoes, clothing, gloves, bags, balls, and interiors as substitutes for natural leather. These are required to have higher quality and sensibility, and especially have an elegant natural leather-like appearance, dense surface texture, and natural leather with a well-balanced soft texture that gradually changes from hard to soft from the surface layer. Things are strongly desired.
[0003]
Conventionally, in order to create a natural leather-like appearance, a surface forming method has been proposed in which a resin film that reproduces the texture of natural leather using release paper is attached to a base (for example, see Patent Reference 1). Alternatively, there has been proposed a method in which a porous resin layer is formed on one side of a base layer uniformly filled with the same elastic body, and embossed rolls are used to reproduce the texture of natural leather (for example, see Patent Reference). Reference 2). Furthermore, a method has been proposed in which the same elastic resin as the surface porous layer is filled in the surface layer of the base body continuously with the surface porous layer (for example, see Patent Reference 2).
[0004]
[Patent Document 1]
JP-A-6-184950
[Patent Document 2]
JP-A-11-140779
[0005]
[Problems to be solved by the invention]
However, these methods cannot satisfy all of the desired natural leather-like elegant appearance, precise surface texture and soft texture.
First, the surface forming method using release paper is too uniform and artificial, cannot be said to be a natural leather tone, and cannot form a deep grain pattern.
In addition, a method of forming a porous resin layer in close contact with one surface of a base layer uniformly filled with the same elastic body, and embossing the natural leather by embossing rolls, reproduces the natural leather grain. Although an appearance can be obtained, a method in which a slightly harder resin is used for the surface layer and a softer resin is filled in the base layer in order to obtain a natural leather-like dense surface feel and soft texture can be considered. However, in this method, there is an abrupt difference between the dense surface layer and the soft base layer, resulting in an unbalanced texture, making it difficult to obtain a desired texture.
[0006]
Furthermore, in the method in which the same elastic resin as the surface porous layer is filled into the surface of the base body continuously with the surface porous layer, a natural leather-like appearance can be obtained by embossing and a slightly harder resin is applied to the surface layer. In addition, if a soft resin is used for the base layer, the same resin as the skin layer is present on the base layer surface layer. Resin differences appear, and a well-balanced texture cannot be obtained.
[0007]
[Means for Solving the Problems]
The present inventors have conducted intensive studies in order to achieve the above-mentioned object, and as a result, have widely used shoes, bags, and the like, which have a natural leather-like elegant appearance, a fine surface texture, and a soft texture. It has been found that a leather-like sheet that can be obtained can be obtained.
That is, the present invention provides a fibrous base layer in which an entangled space of a three-dimensional entangled nonwoven fabric made of ultrafine fibers having a single fiber fineness of 0.2 dtex or less is filled with an elastic resin mainly composed of polyurethane, and a surface of the fibrous base layer. In a leather-like sheet comprising a surface porous layer and a surface finishing layer which are in close contact with each other, the surface porous layer is made of polyurethane resin A having a modulus of 100% a, and an upper layer portion in the fibrous base material layer which is in close contact with the surface porous layer is A polyurethane resin B having a 100% modulus b and a polyurethane resin C having a 100% modulus c in a lower layer portion of the fibrous base material layer, and satisfy the following (1) and (2). Leather-like sheet.
20 <ab (1)
20 <bc (2)
And it is preferable that the polyurethane resin B is a resin which is less likely to be thermally deformed than the polyurethane resin A.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
First, it is important that the fibrous base material used in the present invention has a single fiber fineness of 0.2 dtex or less, and is preferably a three-dimensional entangled nonwoven fabric composed of a bundle of ultrafine fibers having a single fiber fineness of 0.0001 to 0.05 dtex. And a porous structure of an elastic polymer existing in the entangled space. A bundle of ultrafine fibers having a single fiber fineness of 0.2 dtex or less is produced by a conventionally known method. For example, it can be obtained by dissolving or decomposing at least one component from an ultrafine fiber-generating fiber composed of at least two types of polymers, or by peeling off at an interface between the two components by a mechanical or chemical treatment. In order to reduce the single fiber fineness of the ultrafine fibers constituting the obtained bundle of ultrafine fibers to 0.2 dtex or less, the ultrafine fibers having a sea-island structure in the fiber cross-section rather than using the bonded type ultrafine fiber generating fibers It is advantageous in the process to use the generated fiber.
[0009]
Examples of the polymer constituting the ultrafine fibers in the ultrafine fiber-generating fibers include melt-spinnable polyamides such as 6-nylon and 66-nylon, polyethylene terephthalate, polybutylene terephthalate, and cationic dyeable modified polyethylene terephthalate. And at least one polymer selected from melt-spinnable polyesters.
The component to be dissolved or decomposed and removed is a polymer having a difference in solubility or decomposability with respect to a solvent or a decomposer from the microfiber component, and having low compatibility with the microfiber component, and under spinning conditions. It is a polymer having a lower melt viscosity or a lower surface tension, and is, for example, at least one polymer selected from polymers such as polyethylene, polystyrene, polyethylene propylene copolymer, and modified polyester.
[0010]
The ultrafine fiber-generating fibers are defibrated with a card, formed into a web through a webber, and the obtained fibrous web is laminated to a desired weight and thickness, and then is subjected to known techniques such as needle punching and high-speed water flow. To obtain a three-dimensional entangled nonwoven fabric. A woven or knitted fabric can be laminated on the web as needed. The three-dimensional entangled nonwoven fabric only needs to have a surface made of ultrafine fiber-generating fibers, but it is preferable that the entire fiber sheet is made of ultrafine fiber-generating fibers or ultrafine fibers from the viewpoint of the feeling of the obtained sheet. In order to form a three-dimensional entangled nonwoven fabric as a substrate layer having a smooth surface, it is preferable to smooth the surface by a press treatment or the like before impregnation with the elastic polymer.
The thickness of the three-dimensional entangled nonwoven fabric or the nonwoven fabric obtained by pressing can be arbitrarily selected depending on the use of the obtained leather-like sheet and the like, and is not particularly limited. It is preferably about 2 to 10 mm, more preferably about 0.4 to 5 mm. Density is 0.15g / cm ³ ~ 0.50g / cm ³ Is preferred, and 0.20 g / cm ³ ~ 0.40 g / cm ³ Is more preferred. 0.15g / cm ³ If the amount is less than the above, the amount of the resin to be impregnated is increased, resulting in a rubber-like texture, and the peel strength is also reduced. 0.50g / cm ³ When the ratio exceeds, the texture of the obtained leather-like sheet tends to be hard.
[0011]
Next, the three-dimensional entangled nonwoven fabric is filled with a polyurethane resin solution or dispersion, coated with the polyurethane resin solution or dispersion, and then coagulated to form a porous film layer.
Preferred representative examples of the polyurethane to be impregnated and coated include one or more polymer diols such as polyester diol, polyether diol, polyester ether diol, and polycarbonate diol, and an organic polyisocyanate, preferably Polyurethane obtained from one or more aliphatic, aromatic or alicyclic organic diisocyanates and a chain extender having two active hydrogen atoms such as low molecular weight diols, low molecular weight diamines and hydrazine Is raised.
[0012]
A preferable representative example is a polyurethane obtained from a hard segment mainly composed of polymer glycol having a molecular weight of 500 to 5000 having hydroxyl groups at both terminals, 4,4'-diphenylmethane-diisocyanate and a lower alkylene glycol having 2 to 6 carbon atoms. Or polyurethane obtained from a hard segment mainly composed of polymer glycol having a hydroxyl group at both terminals and having a molecular weight of 500 to 5,000, an aliphatic or alicyclic diisocyanate, an organic diamine or an organic acid dihydrazide. However, in consideration of softness, durability, workability, porous film forming property, and the like, a copolymer or a mixture of these may be used.
[0013]
Examples of the polymer glycol having a molecular weight of 500 to 5,000 having hydroxyl groups at both terminals include polyester glycols such as polyethylene adipate glycol, polybutylene adipate glycol, polyhexamethylene adipate glycol, and polycaprolactone glycol, and polyhexamethylene carbonate glycol. Polyether glycols such as polycarbonate glycol, polyethylene ether glycol, polypropylene ether glycol, polytetramethylene ether glycol, and polyhexamethylene ether glycol, and mixtures thereof are used. In particular, polyester glycol, polycarbonate glycol or Polyester glycol and polycarbonate glycol If glycol, polyester glycol, a mixed glycol and polycarbonate-based glycol and a polyether-based glycol preferably.
[0014]
Examples of the aliphatic diisocyanate include tetramethylene diisocyanate and hexamethylene diisocyanate, examples of the alicyclic diisocyanate include cyclohexane diisocyanate and 4,4'-dicyclohexylmethane-diisocyanate, and examples of the aromatic diisocyanate include 4,4 ' -Diphenylmethane-diisocyanate. Examples of the organic diamine include p-phenylenediamine, metaphenylenediamine, 4,4′-diaminediphenylmethane, ethylenediamine, propylenediamine, diethanolamine, 4,4′-diaminodicyclohexylmethane, and isophoronediamine.Examples of the organic acid dihydrazide include: Adipic dihydrazide, sebacic dihydrazide, terephthalic dihydrazide, isophthalic dihydrazide and the like can be mentioned.
[0015]
Representative examples of the lower alkylene glycol having 2 to 6 carbon atoms include ethylene glycol, butanediol, hexanediol, diethylene glycol, dipropylene glycol, and the like. Among them, ethylene glycol is preferred because good embossability can be obtained. Here, the polyurethane elastomer used has a mass percentage (hereinafter referred to as N%) of nitrogen atoms constituting an isocyanate group in the organic polyisocyanate used for synthesizing the polyurethane elastomer with respect to the total mass of the polyurethane elastomer. Preference is given to polyurethane elastomers of 5 to 5% or polymer mixtures based on these polyurethane elastomers. When N% is less than 2.5%, the resulting surface porous layer or fibrous base layer tends to be inferior in abrasion resistance and scratch resistance, and when N% exceeds 5%, Bending wrinkles become rough, the texture is hard, and the resulting leather-like sheet becomes cheap, and the bending fatigue resistance tends to decrease.
[0016]
As the polyurethane resin used for the surface porous layer, a polyurethane resin capable of forming a natural leather-like grain by embossing embossing and providing a dense surface feel is used. Preferred polyurethane resins have a 100% modulus of 50 to 150 kg / cm. ² And more preferably 60 to 100 kg / cm ² It is. 50kg / cm ² If less than 150 kg / cm, a dense surface texture cannot be obtained. ² If it exceeds, the surface feel becomes hard and versatility is lost. The thickness of the surface porous layer is preferably from 0.02 to 1.50 mm, more preferably from 0.05 to 1.00 mm. When the thickness is less than 0.02 mm, a smooth surface cannot be obtained, and the embossing pressability tends to be poor, so that it is difficult to obtain a dense surface feel and a soft texture which is one of the effects of the present invention, If it exceeds 1.50 mm, it tends to have a rubber-like texture.
[0017]
The fibrous base layer (hereinafter sometimes abbreviated as the base layer) is also filled with the polyurethane resin, and the upper layer portion (hereinafter sometimes abbreviated as the upper layer of the base layer) in the base layer which is in contact with the surface porous layer is particularly filled with the polyurethane resin. The 100% modulus of the slightly softer eyes than the polyurethane resin A forming the layer is 40 to 130 kg / cm. ² The polyurethane resin B has a 100% modulus of 30 to 100 kg / cm in consideration of the balance with the upper layer, with emphasis on softness in the lower layer portion (hereinafter sometimes abbreviated as the lower layer of the base layer) in the base layer. ² Is impregnated with the polyurethane resin C.
[0018]
The target is that the polyurethane resin A forming the surface porous layer is slightly harder, and the polyurethane resin B in the upper layer of the base layer and the polyurethane resin C in the lower layer of the base layer become softer sequentially than the polyurethane resin A forming the surface porous layer. A fine surface feel and a soft texture gradually changing from hard to soft from the surface layer are obtained. That is, when the 100% modulus a of the polyurethane resin A in the surface porous layer, the 100% modulus b of the polyurethane resin B in the upper layer of the base layer, and the 100% modulus c of the polyurethane resin C in the lower layer of the base layer are as follows. It is important that there is a relationship.
20 <ab (1)
20 <bc (2)
When only the value of ab is 20 or less, there is no significant difference between the polyurethane resin A of the surface porous layer and the polyurethane resin B of the upper layer of the base layer, and the polyurethane resin B of the upper layer of the base layer and the polyurethane resin B of the lower layer of the base layer are not significantly different. A sharp difference is created between the polyurethane resin C and the polyurethane resin A that forms the target surface porous layer, and the polyurethane resin A that forms the target surface porous layer is slightly harder. A structure having softer eyes is not obtained sequentially than the polyurethane resin A forming the layer, and a desired fine surface feel and a soft texture gradually changing from hard to soft from the surface layer cannot be obtained. When only the value of bc is 20 or less, there is no significant difference between the polyurethane resin B in the upper layer of the base layer and the polyurethane resin C in the lower layer of the base layer. In this case, a sharp difference is made in the polyurethane resin B. Also in this case, the polyurethane resin A forming the target surface porous layer is slightly hard, and the polyurethane resin B in the upper layer of the base layer and the polyurethane resin C in the lower layer of the base layer form the surface porous layer. A structure having softer eyes is not obtained sequentially than the polyurethane resin A to be formed, and a desired fine surface texture and a soft texture gradually changing from hard to soft from the surface layer cannot be obtained. When both the values of ab and bc are 20 or less, the texture of the obtained leather-like sheet has a sense of unity, but it is difficult to obtain a natural leather-like texture with a sense of fulfillment. Accordingly, the leather-like sheet in which the polyurethane resin A forming the target surface porous layer is slightly harder, and the polyurethane resin B in the upper layer of the base layer and the polyurethane resin in the lower layer of the base layer are successively softer than the polyurethane resin forming the surface porous layer. In order to obtain the constitution, it is preferable that there is a clear difference between the resins C of a, b, and c, and that the resin C has continuity. The value of ab exceeds 20 and the value of bc exceeds 20 In order to obtain more distinctive surface softness and a well-balanced sense of fulfillment, there is a clear difference between the resins a, b, and c, and it is preferable that the resins have continuity. In order to obtain a soft texture in which the surface gradually changes from hard to soft, it is more preferable that the value of ab is 30 or more and the value of bc is 30 or more.
Further, from the viewpoint of a feeling of unity of the obtained leather-like sheet, the values of ab and bc are preferably 70 or less, more preferably 60 or less, and particularly preferably 50 or less.
[0019]
And, preferably, the entangled space of the three-dimensional entangled nonwoven fabric constituting the upper layer portion in the base layer in contact with the surface porous layer is less likely to be thermally deformed than the polyurethane resin A forming the surface porous layer. Is used. This is because when the surface porous layer is thermally deformed and fixed by the embossing embossing process, the substrate layer is hardly thermally deformed and retains flexibility. For this reason, it is preferable to select a polyurethane resin having a higher heat deformation fixing property (the sponge structure is less likely to collapse) than the polyurethane resin constituting the surface porous layer in the upper layer portion in the base layer. Specifically, the polyurethane resin used for the surface porous layer and the polyurethane resin used for the upper layer portion in the base layer have a heat deformation fixability ratio of 1.05 to 2.0, preferably 1. Use 10-1.50. When the heat-deformation fixing ratio is less than 1.05, the material tends to be deformed during embossing in the same manner as the surface porous layer, and the texture of the substrate layer tends to harden. On the other hand, when the heat distortion fixability ratio exceeds 2.0, the sense of unity between the surface porous layer and the base layer generated during embossing is impaired, and the texture tends to be inferior.
[0020]
Further, the polyurethane resin A, B, or C constituting the surface porous layer, the upper layer portion in the base layer, and the lower layer portion in the base layer has a 100% modulus and a heat deformation fixing ratio within the range of the present invention. The means can be appropriately adjusted using a known polyurethane production method.
[0021]
The amount of the polyurethane resin to be filled in the substrate layer is such that the amount of the polyurethane resin in the substrate layer is not impaired.
The filling amount is set at 0.3 to 3.0 times, preferably 0.8 to 2.0 times, the solid content of the nonwoven fabric to be filled. If it is less than 0.3 times the fiber mass of the nonwoven fabric, the effect of improving the texture due to the difference in the modulus of the present invention is hardly obtained, the binder effect with the fibers is weak, and the necessary strength is not obtained. When the ratio is more than twice, the fibers are fixed too much and the density becomes too high, so that the base layer becomes hard and the commercial value is easily damaged.
[0022]
The polyurethane layer filled in the upper layer portion of the base layer in contact with the surface porous layer has a thickness of, for example, 0.1 mm to 1.0 mm, preferably 0.2 mm to 0.6 mm, depending on the thickness of the base layer. Preferably it is present. If the layer thickness is less than 0.1 mm, it does not serve as a buffer zone between the skin layer and the lower part of the base layer, and if it exceeds 1.0 mm, the ratio of the upper part of the base layer becomes too large, and The balance with the lower part of the layer is lost, and it is difficult to obtain the expected well-balanced soft texture that gradually changes from hard to soft from the skin layer.
Further, the preferable mass ratio of the polyurethane resin constituting the upper layer portion and the lower layer portion in the base layer is from 10:90 to 60:40, more preferably from 20:80 to 40:60 on a solid basis. Even if the upper layer portion is less than 10% or exceeds 60%, the balance between the skin layer and the lower portion of the base layer is broken as described above, and it is expected that the skin layer gradually changes from hard to soft. It is difficult to obtain a well-balanced soft texture.
[0023]
For the impregnation of the substrate layer with the polyurethane solution, the following several methods are preferred.
First, a predetermined amount of a solution composed of the polyurethane resin B for the upper layer of the substrate is applied to the three-dimensional entangled nonwoven fabric from the upper surface, and the solution is naturally penetrated or penetrated by rubbing with a roll or a knife. There is a method in which a solution composed of C is permeated so as to be rubbed with a roll or a knife and the excess is scraped off with a knife or the like.
Alternatively, the entire nonwoven fabric is once filled with a solution composed of the polyurethane resin C for the lower layer of the substrate, and then compressed with a roll or a knife. Immediately thereafter, the solution composed of the polyurethane resin B for the upper layer of the substrate is coated to increase the resilience of the nonwoven fabric. A method in which the excess is protruded from the three-dimensional entangled nonwoven fabric and then scraped off with a knife can also be used.
[0024]
In order to form a surface porous layer on a substrate filled with a polyurethane solution, a method of coating a solution comprising polyurethane resin A on the upper surface of the substrate layer before solidifying the resin of the substrate layer, or a method of coating a polyurethane layer on the substrate layer There is a method in which the polyurethane of the base layer is coagulated in a coagulating liquid after impregnating the resins B and C, and after drying, the surface of the base layer is coated with a solution comprising the polyurethane resin A. Considering the adhesion between the base layer and the surface porous layer And a method of subsequently coating after impregnation and then simultaneously coagulating the polyurethane solution constituting the base layer and the surface porous layer. Adhesion refers to a state in which the surface of the upper layer portion of the base layer and the surface porous layer are continuously bonded substantially without any intervening substances other than the two layers, and refers to a case in which the surface is different from a state in which they are partially in contact with each other. . The state of being in partial contact means that the surface of the base layer and the surface porous layer are point-adhered by applying a polyurethane solution or the like with a gravure roll or the like to the surface of the base layer upper layer portion and laminating the surface porous layer. It refers to a case where the surface of the upper layer portion of the base layer and the surface porous layer are dry-bonded with a cross-linked polyurethane adhesive.
Examples of the method of coagulating polyurethane include a method of immersing in a liquid containing a non-solvent of polyurethane and wet coagulating, or a method of heating and drying after gelling.The base layer and the surface porous layer have a soft porous structure. A wet coagulation method that can be used is preferably used.
In addition, additives such as a colorant, a coagulation regulator, an antioxidant, and a dispersant are added to the polyurethane solution as needed. Then, a small amount of another resin such as polyurethane may be added as long as the effect of the invention is not changed.
[0025]
Next, the ultrafine fiber-generating fiber is treated with at least one dissolving or decomposing agent, or peeled off at the interface between the two components by a mechanical or chemical treatment to be modified into an ultrafine fiber bundle. The modification process of the ultrafine fiber-generating fiber may be before the application of the polyurethane resin.However, when the ultrafine fiber bundle is impregnated and solidified with the polyurethane resin after the modification, the polyurethane resin adheres to the ultrafine fiber and the texture tends to be hard. It is preferred that the resin be modified after the polyurethane resin is applied. When the denaturation treatment is performed before the polyurethane resin is applied, the polyurethane resin is applied after a temporary filler that can be dissolved and removed such as polyvinyl alcohol is applied so that the ultrafine fibers do not adhere to the polyurethane resin, and then the temporary filler is applied. Is preferably removed.
[0026]
The fibrous base layer made of the three-dimensional entangled nonwoven fabric obtained above and an elastic polymer mainly composed of polyurethane resin and having a surface porous layer is obtained by finishing by the following method to obtain a natural leather-like appearance. Can be done. That is, an ink composed of a coloring agent such as a pigment or a dye and a resin is transferred to a substrate surface by a technique such as a gravure roll, a reverse roll, or a screen and colored to form a surface finishing layer. The preferable thickness of the surface finishing layer is preferably in the range of 2 to 20 μm in order to secure the surface strength without impairing the characteristics of the surface porous layer. Next, emboss rolls are used to emboss to reproduce natural leather-like grain. The sheet thus obtained had a high-quality appearance of natural leather. Further, embossing conditions for imparting a natural leather-like appearance by embossing are preferably in the range of a heating temperature of the embossing roll of 120 ° C to 250 ° C. When the heating temperature is lower than 120 ° C., depending on the softening temperature of the polyurethane resin forming the surface porous layer, emboss squeezing spots may occur.If the heating temperature exceeds 250 ° C., squeezing deformation may occur. In some cases, the softening of the polyurethane resin in the base layer may be caused and the texture may be hardened. Press pressure of embossing roll is 0.5kg / cm ² ~ 8kg / cm ² Is preferable. 0.5kg / cm ² If less than 8 kg / cm ² If the ratio exceeds the above range, the lower layer of the base layer may become dull and the texture may become hard. In order to combine the flexibility of the obtained leather-like sheet with the appearance of natural leather, it is more preferable to use a high-temperature, low-pressure press to achieve a dense surface texture and a well-balanced softness that gradually changes from hard to soft from the surface layer. Heating temperature 130-190 ° C, pressing pressure 1-5kg / cm in terms of easy texture ² Range.
Furthermore, by performing a mechanical kneading treatment or a relaxation treatment with a liquid jet dyeing machine or the like after the embossing stamping, natural kneading wrinkles are formed, the softness is increased, and a natural sense of quality can be increased. Also, apply a resin that can be dyed with a dye at the time of gravure coloring, and if you color it with a dye with a dyeing machine after embossing, it will be colored with transparency, natural shrink etc. will be expressed, and the softness will also increase , A higher sense of quality can be obtained.
[0027]
FIG. 1 shows a schematic view of an example of the leather-like sheet of the present invention. FIG. 1 shows a cross section. From the surface of the leather-like sheet, a surface finishing layer (1), a surface porous layer (2), and a fibrous base (3) are laminated in this order, and the fibrous base is an upper layer (4). ) And the lower layer (5).
The heat deformation stability described in the text is evaluated by the following method.
<Measuring sample creation>
50 parts by mass of polyethylene having a melt index of 70 as a sea component and 50 parts by mass of 6-nylon as an island component were melt-spun in the same melting system to produce a conjugate fiber having a single fiber fineness of 10 dtex and about 300 islands. The composite fiber was stretched 3.0 times, crimped, cut into a fiber length of 51 mm, defibrated with a card, and then made into a web with a cross wrapper webber. Next, the number of punches is 500 punches / cm with a 9 barb needle. ² Needle punching under the conditions described above, and pressing with a roll heated to 120 ° C., thickness 2.17 mm, basis weight 650 g / m 2 ² , Density 0.30g / cm ³ To create a fiber entangled nonwoven fabric.
This nonwoven fabric is impregnated with a 13% solution of polyurethane to be evaluated in dimethylformamide (hereinafter sometimes abbreviated as DMF) and solidified in a coagulation bath of DMF / water = 30/70 at a temperature of 40 ° C. to form a porous structure. . Subsequently, after washing with water, the polyethylene in the conjugate fiber is extracted and removed with toluene heated to 90 ° C. to prepare a sample composed of 0.01 dtex 6-nylon ultrafine fiber bundle fiber and polyurethane.
[0028]
<Evaluation of heat deformation stability>
2.0 kg / cm of the above sample in a flat mold heated to 150 ° C. without clearance ² And pressure-bonded for 10 seconds.
Thereafter, the thickness after compression with a flat plate mold is measured at three points, and the average of these is defined as T. T is defined as the heat-deformation fixing property, and the larger the value is, the less likely it is to collapse, and the smaller the value is, the more likely it is to collapse.
Thickness after compression of the samples to be compared (T1: thickness after compression when using urethane resin constituting the surface porous layer, T2: compression when using urethane resin constituting the upper layer portion in the base layer) Is calculated, and this ratio is referred to as a heat deformation fixedness ratio.
Heat deformation fixedness ratio = T2 / T1
[0029]
【Example】
Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. The parts and percentages in the examples relate to mass unless otherwise specified. The single fiber fineness referred to in the present invention is a value obtained by counting the number of ultrafine fibers constituting a fiber bundle from a micrograph of a cross section of the fiber bundle, and dividing the total fineness of the fiber bundle by the number.
[0030]
Example 1
50 parts by mass of polyethylene as the sea component and 50 parts by mass of 6-nylon as the island component were melt-spun in the same melting system to produce a composite fiber having a fineness of 10 dtex. The composite fiber was stretched 3.0 times, crimped, cut into a fiber length of 51 mm, defibrated with a card, and then made into a web with a cross wrapper webber. Next, with a needle punch, a basis weight of 650 g / m ² Fiber entangled nonwoven fabric. This nonwoven fabric is composed of polyhexacarbonate glycol, polymethylene propylene adipate and methylene diamine, and is copolymerized with n-hexane diisocyanate, 4,4'-diphenylmethane-diisocyanate (hereinafter abbreviated as MDI), and ethylene glycol (hereinafter abbreviated as EG). 100% modulus 40kg / cm ² Impregnated with 18% dimethylformamide solution of polycarbonate-based polyurethane, and pressed with a knife to compress to 70% of the thickness of the nonwoven fabric. Immediately after that, the soft segment was composed of polytetramethylene glycol, polycaprolactone and polyethylene glycol of 67.5: 22. A mass ratio of 5:10, 100% modulus 70 kg / cm copolymerized with MDI, 4,4'-diaminediphenylmethane (hereinafter abbreviated as DAM) and EG. ² 18% dimethylformamide solution of polyurethane (T2 = 1.05 mm) was coated and penetrated, and the solution that could not be penetrated was scraped off with a knife, and then copolymerized with polyethylene propylene adipate, MDI, and EG on the upper surface. 100% modulus 100kg / cm ² Is coated with a 20% dimethylformamide solution of polyester polyurethane (T1 = 0.80 mm), and solidified in a coagulation bath at a ratio of DMF / water = 30/70 to form a porous structure. Subsequently, after washing with water, polyethylene in the composite fiber was extracted and removed to obtain a 1.3 mm-thick fibrous base material composed of 6-nylon ultrafine fiber bundle-shaped fiber composed of 0.01 dtex ultrafine fiber and polyurethane. . The surface porous layer having a thickness of 0.2 mm was in intimate contact with the fibrous substrate, and the polyurethane having the surface porous layer and the upper layer of the substrate layer had a heat deformation fixing ratio of 1.3.
The polyurethane layer in the upper layer of the substrate in contact with the surface porous layer in the substrate has a thickness of 0.3 mm, the ratio of fiber to polyurethane is 50/50 by mass, and the lower layer has a ratio of fiber to polyurethane of And the mass ratio was 60/40.
[0031]
A polyurethane liquid containing a brown pigment was applied to the surface of the substrate with a gravure roll to form a surface finishing layer having a thickness of 5 μm. Then, the embossing roll heated to 150 ° C. was pressed at a pressure of 2 kg / cm for 30 seconds. ² To give a natural leather tone pattern. Further, by rubbing with a rubbing machine, a leather-like sheet having a natural leather-like graceful external feeling, a fine surface feel, and a well-balanced soft texture gradually changing from hard to soft from the surface layer was obtained.
[0032]
Example 2
From the upper layer of the same nonwoven fabric as in Example 1, the mass ratio of polytetramethylene glycol and polycaprolactone was 70:30, and a 100% modulus of 70 kg / cm copolymerized with MDI, DAM and EG. ² Coated with 18% dimethylformamide solution of polyurethane (T2 = 1.05 mm), rubbed by rubbing with a roll, scraping off the solution that could not penetrate with a knife, and then 100% modulus 40 kg / cm from the lower layer. ² The polycarbonate-based polyurethane 18% dimethylformamide solution was lifted from a pan with a roll and impregnated by rubbing, and the solution that did not penetrate was scraped off with a knife. Further, the 100% modulus 100 kg / cm ² Was coated with a 16% dimethylformamide solution (T1 = 0.80 mm) of a polyurethane mainly composed of a polyester-based polyurethane, and coagulated in a coagulation bath of DMF / water = 30/70 to obtain a porous structure. Subsequently, after washing with water, polyethylene in the composite fiber was extracted and removed to obtain a 1.3 mm-thick fibrous base material composed of 6-nylon ultrafine fiber bundle-shaped fiber composed of 0.01 dtex ultrafine fiber and polyurethane. . Then, the surface porous layer having a thickness of 0.2 mm was in close contact with the fibrous base material, and the ratio of the polyurethane to the upper part of the surface porous layer and the base layer in the base material layer to heat deformation fixing ratio was 1.3.
The polyurethane layer in the upper layer of the substrate in contact with the surface porous layer in the substrate has a thickness of 0.3 mm, the ratio of fiber to polyurethane is 50/50 by mass, and the lower layer has a ratio of fiber to polyurethane of And the mass ratio was 60/40.
[0033]
A polyurethane liquid containing a brown pigment was applied to the surface of the substrate with a gravure roll to form a surface finishing layer having a thickness of 5 μm. Then, the embossing roll heated to 150 ° C. was pressed at a pressure of 2 kg / cm for 30 seconds. ² To give a natural leather-like pattern. Further, by rubbing with a rubbing machine, a leather-like sheet having a natural leather-like graceful external feeling, a fine surface feel, and a well-balanced soft texture gradually changing from hard to soft from the surface layer was obtained.
[0034]
Comparative Example 1
A 100% modulus of 60 kg / cm was applied to a nonwoven fabric made of the same microfiber-generating fiber as in Example 1. ² After impregnating with a 13% dimethylformamide solution of a polyurethane mainly composed of polycarbonate-based polyurethane, a knife is pressed against the solution to compress it to 70% of the thickness of the nonwoven fabric, and immediately thereafter, the 100% modulus is 60 kg / cm. ² After coating with a 13% dimethylformamide solution of polyurethane (T2 = 0.80 mm) mainly composed of polycarbonate-based polyurethane, penetrating by using the resilience of the non-woven fabric, scraping off the solution that could not penetrate with a knife And the same 100% modulus 60 kg / cm ² Is coated with a 18% dimethylformamide solution of polycarbonate-based polyurethane (T1 = 0.80 mm), and coagulated in a coagulation bath of DMF / water = 30/70 to obtain a porous structure. Subsequently, after washing with water, polyethylene in the composite fiber was extracted and removed to obtain a 1.3 mm-thick fibrous base material composed of 6-nylon ultrafine fiber bundle-shaped fiber composed of 0.01 dtex ultrafine fiber and polyurethane. . The surface porous layer having a thickness of 0.2 mm was in intimate contact with the fibrous substrate, and the ratio of the polyurethane of the surface porous layer and the polyurethane on the substrate layer to the heat deformation fixing property was 1.0.
The polyurethane layer in the upper layer of the substrate in contact with the surface porous layer in the substrate has a thickness of 0.3 mm, the ratio of fiber to polyurethane is 50/50 by mass, and the lower layer has a ratio of fiber to polyurethane of And the mass ratio was 60/40.
[0035]
A polyurethane liquid containing a brown pigment was applied to the surface of the substrate with a gravure roll to form a surface finishing layer having a thickness of 5 μm. Then, the embossing roll heated to 150 ° C. was pressed at a pressure of 2 kg / cm for 30 seconds. ² To give a natural leather-like pattern. Furthermore, it was made into a kneaded product with a kneader.
This product had a similar texture as a whole, and did not provide the expected fine surface texture and a well-balanced soft texture that gradually changes from hard to soft from the surface layer.
[0036]
Comparative Example 2
A 100% modulus of 40 kg / cm was applied to a nonwoven fabric made of the same ultrafine fiber-generating conjugate fiber as in Example 1. ² After impregnating with a 13% dimethylformamide solution of polyurethane mainly composed of polycarbonate-based polyurethane, a knife is pressed against the solution to compress it to 70% of the thickness of the nonwoven fabric, and immediately thereafter, the mass ratio of polytetramethylene glycol and polycaprolactone is 70:30. 100% modulus 50 kg / cm copolymerized with MDI, DAM, EG ² Coated with 18% dimethylformamide solution of polyurethane (T2 = 1.05 mm), using the resilience of the non-woven fabric to penetrate the solution, scraping off the solution that could not penetrate with a knife, and then adding a 100% modulus. 80kg / cm ² A 20% polyurethane dimethylformamide solution (T1 = 1.05 mm) mainly composed of a polyester-based polyurethane is coated and solidified in a coagulation bath having a DMF / water ratio of 30/70 to obtain a porous structure. Subsequently, after washing with water, polyethylene in the composite fiber was extracted and removed to obtain a 1.3 mm-thick fibrous base material composed of 6-nylon ultrafine fiber bundle-shaped fiber composed of 0.01 dtex ultrafine fiber and polyurethane. . The surface porous layer having a thickness of 0.2 mm was in intimate contact with the fibrous substrate, and the ratio of the polyurethane of the surface porous layer and the polyurethane on the substrate layer to the heat deformation fixing property was 1.0.
The polyurethane layer in the upper layer of the substrate in contact with the surface porous layer in the substrate has a thickness of 0.3 mm, the ratio of fiber to polyurethane is 50/50 by mass, and the lower layer has a ratio of fiber to polyurethane of And the mass ratio was 60/40.
[0037]
A polyurethane liquid containing a brown pigment was applied to the surface of the substrate with a gravure roll to form a surface finishing layer having a thickness of 5 μm. Then, the embossing roll heated to 150 ° C. was pressed at a pressure of 2 kg / cm for 30 seconds. ² To give a natural leather-like pattern. Furthermore, it was made into a kneaded product with a kneader.
Since the softness of the polyurethane used for the lower and upper parts of the base layer is similar and the softness of the polyurethane for the surface porous layer is greatly different from that of the surface layer, the softness of the polyurethane changes gradually from hard to soft from the surface layer. The texture was not obtained.
[0038]
Comparative Example 3
100% modulus 40 kg / cm on the same nonwoven fabric as in Example 1 ² After impregnation with a 13% dimethylformamide solution (T2 = 0.8 mm) of a polyurethane composed mainly of a polycarbonate-based polyurethane, the mixture is coagulated in a coagulation bath having a DMF / water ratio of 30/70 to obtain a porous structure. Subsequently, after washing with water, the polyethylene in the composite fiber was extracted and removed to obtain a fibrous base material having a thickness of 1.1 mm and comprising a bundle of 6-nylon ultrafine fibers made of ultrafine fibers of 0.01 dtex and polyurethane. .
100% modulus 80 kg / cm ² A 20% polyurethane solution of dimethylformamide (T1 = 1.05 mm) mainly composed of a polyester-based polyurethane was coated and solidified in a coagulation bath of DMF / water = 30/70 to form a porous film. The ratio of the polyurethane in the surface porous layer and the polyurethane in the upper layer portion in the base layer to heat deformation fixing property was 0.8.
The ratio of fibers to polyurethane in this substrate was 50/50 by mass.
[0039]
A polyurethane liquid containing a brown pigment was applied to the surface of the substrate with a gravure roll to form a surface finishing layer having a thickness of 5 μm. Then, the embossing roll heated to 150 ° C. was pressed at a pressure of 2 kg / cm for 30 seconds. ² To give a natural leather-like pattern. Further rubbing was performed with a rubbing machine, but the resulting leather-like sheet had a sharp difference between the slightly harder and denser surface layer and the soft base layer, resulting in an unbalanced texture, It was not possible to obtain a product that had a good balance between the surface texture and the well-balanced soft texture that gradually changed from hard to soft from the surface layer.
[0040]
【The invention's effect】
The present invention relates to a leather-like sheet having a natural leather-like graceful appearance, a fine surface texture, and a well-balanced natural leather that gradually changes from hard to soft from the surface layer, and has a natural soft texture, such as shoes and bags. A leather-like sheet that can be widely used for applications can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically illustrating a leather-like sheet of the present invention.
[Explanation of symbols]
1 Surface finish layer
2 Surface porous layer
3 fibrous substrate
4 Upper layer of fibrous base
5 Lower layer of fibrous base

Claims (2)

A fibrous base layer in which an entangled space of a three-dimensional entangled nonwoven fabric made of ultrafine fibers having a single fiber fineness of 0.2 dtex or less is filled with an elastic resin mainly composed of polyurethane, and a surface porosity in close contact with the surface of the fibrous base layer In the leather-like sheet comprising a layer and a surface finishing layer, the surface porous layer is made of polyurethane resin A having a 100% modulus a, and the upper layer portion of the fibrous base material layer in close contact with the surface porous layer has a 100% modulus b. A leather-like sheet characterized in that a polyurethane resin B and a polyurethane resin C having a modulus c of 100% are filled in a lower layer portion in the fibrous base layer, and the following (1) and (2) are satisfied.
20 <ab (1)
20 <bc (2) The leather-like sheet according to claim 1, wherein the polyurethane resin B is a resin that is less likely to be thermally deformed than the polyurethane resin A.

Images