JP2016211129A - Leather-like sheet, manufacturing method thereof, and method for repairing leather-like sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leather-like sheet capable of self-repairing surface scratches by heating, allowing scratches or compressed marks to be easily repaired by heating.MEANS: The leather-like sheet for use includes a fiber substrate sheet with a surface laminated with a grain layer. The grain layer includes a layer which contains a shape-memory polyurethane elastomer.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a leather-like sheet having a silver-tone resin layer, and more particularly to a leather-like sheet that self-repairs surface scratches, pressing molds, and the like by heating.

  Leather-like sheets such as artificial leather and synthetic leather are widely used as skin materials for bags, shoes and clothing. Scratches and scratches may be formed on the surface of heels, shoes, and clothing using leather-like sheets.

  As a method for suppressing scratches generated on the surface of such a leather-like sheet, for example, the following Patent Document 1 discloses a methacrylic polymer block (a) having a glass transition temperature of 50 to 130 ° C. and acrylic acid- From the acrylic polymer block (b) whose main component is at least one monomer selected from the group consisting of n-butyl, ethyl acrylate, acrylic acid-2-ethylhexyl and acrylic acid-2-methoxyethyl And a (meth) acrylic block copolymer having an acid anhydride group and / or a carboxyl group in at least one of the methacrylic polymer block (a) and the acrylic polymer block (b). Thermoplastic elastomer containing (A) and acrylic polymer (B) having 1.1 or more reactive functional groups (C) in one molecule Over composition (1) discloses a synthetic leather, characterized in that formed by melt film to the fibrous substrate (2). However, even when such a layer is provided on the surface to improve the scratch resistance, there is a problem that the scratches once formed remain, so that the scratches increase with time.

  Moreover, although it is not a technique regarding a leather-like sheet, the following Patent Document 2 discloses an acrylic resin (A) and a polyresin as a self-repairing formable coating composition useful for improving the scratch resistance of automobile exterior plates and plastic molded product surfaces. A self-healing type coating composition comprising an isocyanate (B) and an additive (C), wherein the acrylic resin (A) has a glass transition point of -20 to 30 ° C and a hydroxyl value per acrylic resin solid content. Is 40 to 100 mg KOH / g, and the polyisocyanate (B) has an average number of functional groups of 4 to 6 obtained by reaction of the aliphatic organic diisocyanate (b1) with the polycarbonate diol (b2) having a number average molecular weight of 250 to 750. An allophanate group-containing polyisocyanate, the additive (C) having at least one hydroxyl group It discloses a self-healing type forming coating composition which is a le siloxane-modified product. According to the method of forming such a self-healing layer on the surface of the member, even if a flaw occurs, the flaw becomes inconspicuous by self-healing.

  By the way, the following Patent Document 3 includes a bifunctional diisocyanate having a molecular weight in the range of 160 to 310, a bifunctional polyol having a molecular weight in the range of 400 to 2000, and an active hydrogen group having a molecular weight in the range of 60 to 400. A bifunctional chain extender is used as a raw material, and in a molar ratio, diisocyanate: polyol: chain extender = 2.00 to 1.10: 1.00: 1.00 to 0.10 and polymerized by a prepolymer method. This polyurethane elastomer contains almost equal amounts of [NCO] and [OH] at the end of the polymer immediately after synthesis, and has a glass transition point in the range of −50 to 60 ° C. and a crystallinity of 3 to 50% by weight. And the ratio of the tensile elastic modulus at a temperature higher by 10 ° C. to the elastic modulus at a temperature lower by 10 ° C. than the glass transition point is 50 to 250. A molded body is disclosed.

JP 2009-1950 A JP2012-107101A Japanese Patent No. 2502132

  A leather-like sheet used as a skin material for bags, shoes, clothing, etc., may be exposed to conditions that are very easily damaged depending on the usage mode of general consumers. For example, in the case of a children's bag such as a school bag, it is used every day for a long time to school, and there is a problem that children are particularly easily scratched because they tend to handle the bag roughly.

  Further, the leather-like sheet produced continuously has the following problems. Usually, leather-like sheets having a length of several tens of meters to several hundreds of meters are continuously produced and stored, transported, etc. in a state of being wound around a core material as a roll-shaped fabric. A step due to the thickness of the surface of the core material and the thickness of the leather-like sheet at the beginning of the winding occurs at the beginning of winding of the roll-shaped fabric wound around the core material. In the case of a leather-like sheet with a silver tone having a silver surface layer containing a polymer elastic body, a step due to the thickness of the leather-like sheet is transferred over several turns at the beginning of winding, and a portion corresponding to the position of the step is transferred. The pressed mold remains on the leather-like sheet. Such a pressing die is formed in order to compress the elastic polymer that forms the silver surface layer, because the tension generated by being wound in a roll shape is strongly applied to the beginning of the roll of the workpiece. The leather-like sheet for several laps from the beginning of winding in which such a pressing mold is formed cannot be used as a product and has been conventionally discarded.

  In order to solve the above-described problems, an object of the present invention is to provide a leather-like sheet in which a mold such as a surface flaw or a pressing mold is repaired by heating.

  One aspect of the present invention is a leather-like sheet in which a silver surface layer is laminated on the surface of a fiber base sheet, and the silver surface layer is a leather-like sheet having a layer containing a shape memory polyurethane elastomer. According to such a configuration, when a layer containing a shape memory polyurethane elastomer is arranged on the surface layer or the inner layer of the silver surface layer, when the leather-like sheet is scratched or molded, the portion is heated. As a result, the molecular motion of the shape memory polyurethane elastomer is rapidly activated, the molecular motion of the portion where the molecular arrangement is changed by the external force is released, and the molecules are rearranged to self-repair the wound and the mold. Therefore, for example, even if the surface of a child's bag such as a school bag is damaged, the wound can be self-repaired by a simple process of heating. Moreover, even if it is a case where the type | mold like the pressing type | mold which is not a damage | wound mentioned above is attached, a type | mold can be lose | disappeared by the simple process of heating.

The shape memory polyurethane elastomer has a glass transition temperature (T _g ) defined as a temperature indicating a peak value of a temperature dependence curve of a loss tangent (tan δ) at a frequency of 1 Hz, and is in a glass transition region. The polyurethane elastomer is preferably a polyurethane elastomer having a temperature range of 25 ° C. or less and a change in tensile elastic modulus before and after the glass transition region of 1.0 × 10 ² times or more. Here, referring to FIG. 3, the glass transition region is a transition region that transitions from a region showing a glass state to a region showing rubbery elasticity in a temperature-dependent curve of the tensile modulus of polyurethane elastomer, intersection of X _1, defines the intersection of the tangent line at the approximate straight line and the T _g of the indicated area of rubber-like elastic from X ₁ when the X ₂ and the region of X ₂ between the tangent line in the approximation straight line and the T _g of the area indicated Is done. If the scratches and types with a layer containing such a polyurethane elastomer, by heating the portions marked with scratches and mold to a temperature above T _g, intensified rapidly molecular motion before and after a T _g Thus, the movement of the wound where the molecular arrangement has been changed by the external force is released and the molecules are rearranged, so that the wound or mold disappears or becomes inconspicuous.

  When the silver layer has a laminated structure and the layer containing the shape memory polyurethane elastomer is a surface coat layer disposed on the outermost layer of the silver layer, the scratches on the surface are heated. This is preferable because it can be repaired. In addition, when the silver layer has a laminated structure and the layer containing the shape memory polyurethane elastomer is arranged in the inner layer of the silver layer, it is repaired by heating the pressing die formed deep inside. It is preferable from the point which can be made.

Another aspect of the present invention is that a glass transition temperature (T _g ) defined as a temperature indicating a peak value of a temperature dependence curve of a loss tangent (tan δ) at a frequency of 1 Hz is 35 to 100 ° C., A polyurethane elastomer film serving as a surface coat layer containing a polyurethane elastomer having a temperature range of 25 ° C. or less in the glass transition region and a change in tensile elastic modulus of 1.0 × 10 ² times or more before and after the glass transition region on the release paper And forming a laminate in which a polymer elastomer film as an inner layer is further laminated on a polyurethane elastomer film, and the surface of the polymer elastic film as an inner layer of the laminate through a bonding layer. comprising a step of bonding the surface of the sheet, and after shaping in the region showing elastomeric existing polyurethane elastomer coating to a temperature range higher the T _g, low the T _g It is a manufacturing method of the leather-like sheet | seat further provided with the process cooled to the area | region which shows the glass state which exists in a high temperature area.

Layer containing a shape memory polyurethane elastomer, after being shaped in the region exhibiting rubber-like elasticity present in the higher temperature range the T _g, the cooling to the region under illustrating a glassy state present in a temperature region lower the T _g In the case of a layer formed by cooling, the rubber-like elastic region is cooled and solidified with the compression applied at the time of shaping, so that the residual strain (internal stress) is greatly accumulated. Shaped. Then, by heating to a temperature above T _g, with the elimination of residual strain, scratches and mold is hardly more quickly lost or noticeable.

Another aspect of the present invention is the above-described method for repairing the appearance of a leather-like sheet, the step of identifying a scratch or mold of the leather-like sheet, and the identified scratch or mold of the shape memory polyurethane elastomer. and heating to a temperature above T _g, is an external repair method of the leather-like sheet comprising a.

  The leather-like sheet of the present invention self-repairs the wound by heating when it is damaged.

FIG. 1 is a schematic cross-sectional view of an artificial leather 10 according to an embodiment. FIG. 2 is an explanatory diagram for explaining a mechanism for self-repairing a surface flaw by heating. FIG. 3 shows a graph of the temperature dependence of the tensile modulus of the polyurethane elastomer used in the examples. FIG. 4 is a schematic cross-sectional view of the artificial leather 20 of the embodiment. FIG. 5 is an explanatory diagram for explaining a mechanism for self-repairing the mold by heating.

[First Embodiment]
A leather-like sheet 10 according to a first embodiment which is an embodiment of a leather-like sheet according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of an artificial leather 10 according to the first embodiment. In FIG. 1, 1 is a fiber base sheet mainly composed of a fiber entangled body, 2 is an adhesive layer formed on the surface of the fiber base sheet, 3 is an adhesive layer 2 on the fiber base sheet 1 The surface coat layer 4 is formed on the surface of the inner layer 3. A laminate of the adhesive layer 2, the inner layer 3, and the surface coat layer 4 forms the silver surface layer 5.

  Examples of the fiber base sheet 1 include a base material obtained by impregnating a polymer entanglement with a fiber entangled body used in the manufacture of artificial leather, a woven fabric used in the manufacture of synthetic leather, and the like. It is done. The inner layer 3 is a layer mainly composed of a polymer elastic body such as a polyurethane elastomer or an acrylic elastic body. A surface coat layer 4 is formed on the surface of the inner layer 3 to self-repair surface flaws by heating.

  The surface coat layer 4 contains a shape memory polyurethane elastomer for repairing scratches attached to the surface coat layer by being heated. Here, the shape memory polyurethane elastomer is a polyurethane elastomer that changes from a glassy region to a region exhibiting rubbery elasticity by being heated and recovers to a shape of a region that exhibits pre-shaped rubbery elasticity. Means.

As a specific example of such a shape memory polyurethane elastomer, for example, a glass transition temperature (T _g ) defined as a temperature indicating a peak value of a temperature dependence curve of a loss tangent (tan δ) at a frequency of 1 Hz is 35. Examples include polyurethane elastomers having a temperature range of ˜100 ° C., a temperature range of the glass transition region of 25 ° C. or less, and a change in tensile elastic modulus before and after the glass transition region of 1.0 × 10 ² times or more. Such polyurethane elastomers are changed to a region exhibiting rubber-like elasticity by being heated to a temperature above T _g, it attempts to recover the originally imparted shape.

  With reference to FIG. 2, a mechanism for self-repairing the surface flaw formed on the artificial leather 10 of the first embodiment by heating will be described. In FIG. 2, 4 is a part of the surface coat layer formed on the artificial leather 10, and 4 a is a scratch formed on the surface of the surface coat layer 4.

As shown in FIG. 2A, the surface coat layer 4 has scratches 4a. Since the surface coat layer 4 contains a shape memory polyurethane elastomer, it is in a frozen glass state in which the molecular chain does not undergo micro-Brownian motion at a temperature lower than its T _g . In this state, since the surface hardness is relatively high, it is difficult to be damaged. However, the scratch 4a once entered is conspicuous in the state of remaining.

As shown in FIG. 2 (b), the surface coating layer 4 of scratching below the melting point of the portion of the wound 4a at a temperature above the T _g, preferably when heated to 10 to 30 ° C. higher temperature than T _g, the surface The shape memory polyurethane elastomer contained in the coat layer 4 is in a state of exhibiting rubber-like elasticity in which the molecular chain moves in micro Brownian motion. At this time, the molecular motion of the polyurethane is rapidly activated, so that the wound disappears or becomes inconspicuous. As a result, the molecular motion of the part where the molecular arrangement has been changed by the external force is released and the molecules are rearranged to repair the wound, thereby closing the scratch 4a. Then, as shown in FIG. 2 (c), the scratch 4a disappears. After scratching 4a is lost, T by being allowed to cool naturally to a temperature lower than _g, the polyurethane returns to frozen high glass state hardness no molecular chains micro Brownian motion again.

  Although the method to heat is not specifically limited, For example, heating by the hot air of a hair dryer, heating by the radiant heat of a heater, etc. are not specifically limited.

  The surface coat layer 4 and the inner layer 3 are bonded to the surface of the fiber base sheet 1 via the adhesive layer 2 by, for example, a so-called dry surface forming method. In the dry surface-forming method, a polyurethane elastomer solution or a molten resin for forming the surface coat layer 4 is applied to a support substrate such as a release paper to form a film, and then the inner layer is formed on the film of the surface coat layer 4. 3 is laminated, and further, an adhesive is applied to the inner layer 3 film, bonded to the surface of the fiber base sheet 1, pressed and bonded, and the release paper is peeled off, and then the adhesive layer 2 is interposed. In this method, the inner layer 3 and the surface coat layer 4 are formed. By peeling the release paper on the surface, an artificial leather 10 having a silver surface layer on which a surface coat layer 4 for self-healing surface scratches by heating is formed.

At this time, in any step after the film formation, by a press coating of the surface coating layer 4 using such hot roll heated to a temperature higher the T _g and compacted under a region exhibiting rubber-like elasticity vehicles Preferably, it is formed so that it is cooled to a temperature showing a glass state in a temperature region lower than T _g before the compression is completely recovered. In such a case, the film forming the surface coat layer is cooled and solidified in a compressed state in the rubber-like elastic region, so that residual strain is easily accumulated in the surface coat layer. Thus the surface coating layer formed, when used as a skin layer of the leather-like sheet, the residual strain by heating to a temperature higher the T _g is eliminated, also molecular movement is released molecules Rearrange the surface so that the surface scratches disappear or become inconspicuous.

  An example of the shape memory polyurethane elastomer will be described in detail.

As an example of the shape memory polyurethane elastomer, for example, a glass transition temperature (T _g ) defined as a temperature indicating a peak value of a temperature dependence curve of a loss tangent (tan δ) at a frequency of 1 Hz is 35 to 100 ° C. There is a thermoplastic polyurethane elastomer having a temperature range of the glass transition region of 25 ° C. or less and a change in tensile elastic modulus before and after the glass transition region of 1.0 × 10 ² times or more.

The T _g of the shape memory polyurethane elastomer is preferably 35 to 100 ° C, more preferably 45 to 80 ° C, and particularly preferably 55 to 75 ° C. If the T _g of the polyurethane elastomer is too high, it takes time to reach the temperature to be repaired by heating, work consumer to repair by heating itself becomes complicated, also, the film is hard It is not preferable as a coat layer of a leather-like sheet that is required to be supple by being too much. Also, if the T _g of the polyurethane elastomer is too low, in the air temperature is high environmental, by surface coating layer decreases surface hardness migrate to a region exhibiting rubber elasticity tends to scratch resistance is lowered .

  Further, when the shape memory polyurethane elastomer has a glass transition region having a temperature range of 25 ° C. or less, and further 20 ° C. or less, when it is heated, it quickly shifts to a region exhibiting rubber elasticity to repair the scratches. This is preferable.

The shape memory polyurethane elastomer preferably has a change in tensile elastic modulus before and after the glass transition region of 1.0 × 10 ² times or more, more preferably 5.0 × 10 ² times or more. In such a case, since the elastic modulus changes abruptly before and after T _g , it is preferable from the viewpoint that polyurethane is extremely easily deformed in a region exhibiting rubber-like elasticity. If the change in tensile modulus is too low, the restorability is low.

Further, the change rate of the tensile elastic modulus at T _g of the shape memory polyurethane elastomer is preferably −0.1 to −100 MPa / ° C., more preferably −0.5 to −50 MPa / ° C. Here, as shown in FIG. 3, the rate of change of the tensile modulus is obtained from the slope at T _g in the graph of the temperature dependence of the tensile modulus of the polyurethane elastomer.

Examples of the shape memory polyurethane elastomer as described above include a bifunctional diisocyanate having a molecular weight in the range of 160 to 310, a bifunctional polyol having a molecular weight in the range of 400 to 2000, and a molecular weight in the range of 60 to 400. A bifunctional chain extender containing an active hydrogen group is used as a raw material, and in a molar ratio, diisocyanate: polyol: chain extender = 2.00 to 1.10: 1.00: 1.00 to 0.10. Polyurethane elastomer polymerized by the prepolymer method, and the end of the polymer immediately after synthesis contains [NCO] and [OH] in substantially equal amounts, a glass transition point in the range of 35 to 100 ° C., and 3 to 50% by mass. Polyurethane elastomers having a degree of crystallinity of

  Specific examples of the bifunctional isocyanate include 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, carbodiimide-modified 4,4'-diphenylmethane isocyanate, hexamethylene diisocyanate, and the like. These bifunctional isocyanates may be used alone or in combination of two or more.

  Specific examples of the bifunctional polyol include polypropylene glycol, 1,4-butane glycol adipate, polytetramethylene glycol, polyethylene glycol, propylene oxide adduct of bisphenol-A, and the like. The bifunctional polyol may be used as a product obtained by further reacting a bifunctional carboxylic acid or cyclic ether, and such a product is also treated as a bifunctional polyol. These bifunctional polyols may be used alone or in combination of two or more.

  Examples of the diol and diamine used as the chain extender include, for example, ethylene glycol, 1,4-butane glycol, bis (2-hydroxyethyl) hydroquinone, bisphenol-A ethylene oxide adduct, bisphenol- A propylene oxide adduct of A and the like can be mentioned. Specific examples of the diamine include ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, m-xylylenediamine, p-xylylenediamine, 4,4′-diphenylmethanediamine, cyclohexylenediamine, 2 , 4-tolylenediamine, 2,6-tolylenediamine, hexamethylenediamine and the like. These chain extenders may be used alone or in combination of two or more.

  The polyurethane elastomer is polymerized by the prepolymer method using the bifunctional isocyanate, the bifunctional polyol, and the chain extender as described above, using the catalyst as necessary. As the ratio of each unit, the ratio of bifunctional isocyanate: bifunctional polyol: chain extender is preferably 2.00 to 1.10: 1.00: 1.00 to 0.10. The polyurethane elastomer may contain various additives such as matting agents (light shielding agents) such as titanium oxide and zinc oxide, antioxidants, and ultraviolet absorbers as necessary.

Such polyurethane elastomers, by forming a pseudo-crosslinking due to partial crystallization instead of the intermolecular crosslinking, the rubber elasticity is maintained at T _g or more while maintaining the thermoplastic, and the deformed shape before and after the glass transition point It has a shape memory property that can be shifted between molded shapes.

In order to form pseudo-crosslinking, the crystallinity is preferably in the range of 3 to 50% by mass. If the crystallinity is too low is reduced rubber elasticity, if the crystallinity is too high, rubber elasticity becomes high at T _g above temperature, the change in elastic modulus before and after T _g decreases.

Specific examples of such polyurethane elastomers include, for example, polyurethane elastomer products of each grade in which (T _g ) of polyurethane-based shape memory polymer “SMP” manufactured by SMP Technologies, Inc. is 35 to 100 ° C., _{is, MS3510 (T g 35 ℃)} , MS4510 (T g 45 ℃), MS5010 (T g 50 ℃), MS5510 (T g 55 ℃), MS6010 (T g 60 ℃), MS8010 (T g 80 ℃), Etc. Such a polyurethane elastomer can be produced, for example, by a method as disclosed in JP-A-02-092914.

  The surface coat layer contains, in addition to the shape memory polyurethane elastomer, various polymer elastic bodies conventionally used for forming the surface coat layer, other additives and colorants, if necessary. Specific examples of the elastic polymer may include, for example, a polyurethane elastomer, an acrylic elastic body, a polyamide elastic body such as a polyamide elastomer, a polyester elastic body such as a polyester elastomer, an elastic polystyrene resin, and an elastic polyolefin resin. , Elastic silicone resin and the like.

  The content ratio of the shape memory polyurethane elastomer contained in the surface coat layer is 15 to 100% by mass, more preferably 25 to 100% by mass, particularly 50 to 100% by mass, especially 80 to 100% by mass. Preferably there is. When the content ratio of the shape memory polyurethane elastomer is too low, the effect of repairing the scratches when heated is likely to be low.

  The thickness of the surface coat layer is not particularly limited, but is preferably 10 to 100 μm, and more preferably 20 to 50 μm. When the thickness of the surface coat layer is too thick, the texture tends to be hard and the bending resistance tends to be poor. Moreover, when too thin, the effect which protects a surface falls, and when the damage | wound which reaches a lower layer enters, there exists a tendency for surface repair property to fall.

  Next, a fiber base sheet for forming a leather-like sheet will be described.

  The form of the fiber base sheet is not particularly limited, and for example, a nonwoven fabric, a woven fabric, a knitted fabric or the like is used. The type of fiber forming the fiber base sheet is not particularly limited. For example, polyethylene terephthalate (PET), modified polyethylene terephthalate, polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polytriethylene terephthalate, Aromatic polyester resins such as polyhexamethylene terephthalate, polypropylene terephthalate, polyethylene naphthalate, polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, polyhydroxybutyrate-polyhydroxyvalylate copolymer Polyester fibers such as aliphatic polyester resins such as polyamide 6, polyamide 66, polyamide 610, polyamide 10, polyamide 11, polyamide 1 Polyamide resins such as polyamide 6-12; polyolefin resins such as polypropylene, polyethylene, polybutene, polymethylpentene, chlorinated polyolefin, ethylene vinyl acetate copolymer, styrene ethylene copolymer; 25 to 70 ethylene units Examples thereof include modified polyvinyl alcohol-based resins formed from a modified polyvinyl alcohol containing mol%; and crystalline elastomers such as polyurethane elastomers, polyamide elastomers, and polyester elastomers. In these, an aromatic polyester-type resin is preferable from the point which is excellent in the balance of various characteristics.

When using a non-woven fabric, the single fiber fineness of the fiber forming the non-woven fabric may be a regular fiber such as more than 0.9 dtex, or an ultrafine fiber such as 0.9 dtex or less, but it is lumpy and supple. When producing an artificial leather with a fine texture, it is preferably an ultrafine fiber. The single fiber fineness of the ultrafine fiber is 0.9 dtex or less, more preferably 0.01 to 0.8 dtex, particularly 0.05 to 0.5 dtex, especially 0.07 to 0.1 dtex. This is preferable because a dense nonwoven fabric can be obtained. Such non-woven fabrics of ultrafine fibers are obtained by, for example, ultrafine treatment of ultrafine fiber-generating fibers such as sea-island cross-section fibers and multilayer laminated cross-section fibers obtained by using a mixed spinning method or a composite spinning method. A fiber entanglement is preferred.

  Moreover, it is preferable to contain a polymer elastic body in the nonwoven fabric at the time of manufacturing artificial leather for the purpose of providing form stability. Specific examples of the polymer elastic body include, for example, a polyurethane elastomer, an acrylic elastic body, a polyamide elastic body such as a polyamide elastomer, a polyester elastic body such as a polyester elastomer, a polystyrene elastic body, a polyolefin elastic body, and an elastic silicone resin. It is done.

  Although the thickness of a fiber base material sheet is not specifically limited, For example, it is preferable that it is about 300-3000 micrometers, Furthermore, about 500-1500 micrometers.

  Next, the inner layer will be described. The inner layer is a layer mainly composed of a polymer elastic body, preferably a colored polymer elastic body. Specific examples of the polymer elastic body include, for example, a polyurethane elastic body, an acrylic elastic body, a polyamide elastic body such as a polyamide elastomer, a polyester elastic body such as a polyester elastomer, a polystyrene elastic body, a polyolefin elastic body, an elastic silicone resin, etc. Is mentioned. Among these, polyurethane elastomers are preferable from the viewpoint of obtaining a leather-like sheet that is excellent in flexibility and fullness.

  The inner layer may be a single layer or may have a multilayer structure with different types of resins. Although the thickness of an inner layer is not specifically limited, It is preferable that it is 10-200 micrometers, Furthermore, it is 40-60 micrometers. If the inner layer is too thick, it tends to have a rubber-like texture.

  The adhesive forming the adhesive layer is not particularly limited as long as it is an adhesive that can sufficiently bond the fiber base sheet and the inner layer. However, when the inner layer is mainly composed of a polyurethane elastomer, a polyurethane adhesive is used. It is preferably used because a leather-like sheet having an excellent balance between adhesiveness and flexibility can be obtained. The thickness of the adhesive layer is not particularly limited, but is preferably 30 to 300 μm, and more preferably 50 to 150 μm. When the thickness of the adhesive layer is too thick, it is not preferable because it has a rubber-like texture, and when it is too thin, the adhesive force tends to decrease.

  The leather-like sheet that self-repairs surface scratches by heating according to the present embodiment is preferably used as a skin material such as bags, shoes, and clothing. In particular, it is preferably used as a skin material for children's heels such as school bags that are exposed to conditions that can be easily damaged depending on the mode of use.

[Second Embodiment]
A leather-like sheet 20 according to a second embodiment, which is an embodiment of a leather-like sheet according to the present invention, will be described with reference to the drawings. In addition, the element which attached | subjected the code | symbol similar to the code | symbol shown in 1st Embodiment points out the element similar to 1st Embodiment, and simplifies description.

  In the leather-like sheet of the first embodiment, a shape memory polyurethane elastomer is contained in the surface coat layer forming the silver layer. On the other hand, in the leather-like sheet 20 of the second embodiment, an example in which a shape memory polyurethane elastomer is contained in the inner layer 13 that forms the silver layer will be described.

  FIG. 4 is a schematic cross-sectional view of the artificial leather 20 of the second embodiment. In FIG. 4, 1 is a fiber base sheet mainly composed of fiber entangled bodies, 2 is an adhesive layer formed on the surface of the fiber base sheet, and 13 is an adhesive layer 2 on the fiber base sheet 1. The surface coat layer 14 is formed on the surface of the inner layer 13. A laminate of the adhesive layer 2, the inner layer 13, and the surface coat layer 14 forms a silver surface layer 15.

  The inner layer 13 is a layer constituting the silver surface layer 15 containing the shape memory polyurethane elastomer, and is substantially the same layer as the inner layer 3 in the first embodiment except that it contains the shape memory polyurethane elastomer. is there.

  The inner layer 13 contains a shape memory polyurethane elastomer that is repaired by heating a pressing die formed so as to be embossed. As the shape memory polyurethane elastomer, the same one as described in the first embodiment is used.

  With reference to FIG. 5, a mechanism for self-repairing the pressing mold formed on the artificial leather 20 of the second embodiment by heating will be described. In FIG. 5, 14 is a surface coat layer formed on the artificial leather 20, 13 is a part of the inner layer, and 13a is a pressing mold.

As shown in FIG. 5A, a pressing die 13 a is formed on the silver surface layer 15. Since the inner layer 13 contains a shape memory polyurethane elastomer, it is in a frozen glass state where the molecular chain does not undergo micro-Brownian motion at a temperature lower than its T _g .

As shown in FIG. 5 (b), when heated to a temperature lower than the melting point of the portion of the pressure-type 13a at a temperature above the T _g of the shape memory polyurethane elastomer, shape memory polyurethane elastomer contained in the inner layer 13 molecules The chain exhibits a rubbery elasticity with micro-Brownian motion. At this time, the molecular motion of the polyurethane is rapidly activated, and the shape memory polyurethane elastomer expands to return to its original shape. Then, as shown in FIG. 2C, the pressing die 13a formed by the external force disappears. After pressure type 13a is lost, T by being allowed to cool naturally to a temperature lower than _g, the polyurethane returns to frozen high glass state hardness no molecular chains micro Brownian motion again.

  The surface coat layer 14 and the inner layer 13 are bonded to the surface of the fiber base sheet 1 via the adhesive layer 2 by, for example, a so-called dry surface forming method. In the dry surface-forming method, a polyurethane solution or a molten resin for forming the surface coat layer 14 is applied on a support substrate such as a release paper to form a film, and then the inner layer 13 is formed on the film of the surface coat layer 14. The inner layer 13 is further laminated by coating the inner layer 13 with an adhesive, adhering it to the surface of the fiber base sheet 1, pressing and adhering, and releasing the release paper. 13 and the surface coat layer 14 are formed. By peeling the release paper on the surface, an artificial leather 20 having a silver surface layer on which an inner layer 13 that self-repairs the mold by heating is formed is obtained.

  The leather-like sheet in which the pressing mold is self-repaired by heating according to the present embodiment is preferably used as a skin material for bags, shoes, clothing, and the like. In particular, it is preferably used for a leather-like sheet which is easily pressed in the manufacturing process, for example, is stored and transported in the form of a roll-shaped fabric that is continuously produced and wound around a core material.

  In addition, although the example which made the surface coat layer 4 in the artificial leather 10 of 1st Embodiment contain the shape-memory polyurethane elastomer in the inner layer 13 in the artificial leather 20 of 2nd Embodiment was demonstrated, this invention is It is not limited to these embodiments. For example, an artificial leather having a single-layer silver surface layer containing a shape memory polyurethane elastomer or a silver surface layer containing a shape memory polyurethane elastomer in an adhesive layer may be used.

  Hereinafter, the present invention will be described more specifically with reference to examples. The scope of the present invention is not limited to these examples.

[Example 1]
A fiber base sheet having a thickness of 0.6 mm was prepared by impregnating a polyurethane elastomer into a nonwoven fabric of PET-based long fibers having a fineness of 0.08 dtex so that the mass ratio of polyurethane elastomer / long fibers was 12/88.

  And the silver surface layer was formed in the fiber base sheet by the dry surface forming method as described below.

After applying a 35 mass% DMF solution of a shape memory polyurethane elastomer having a T _{g of} 55 ° C. (MS5510 of polyurethane-based shape memory polymer “SMP” manufactured by SMP Technologies) at 90 g / m ² on the release paper, By drying at 120 ° C. for 2 minutes, a film of a surface coat layer having a thickness of 25 μm was formed.

Next, a polyurethane elastomer solution for forming an inner layer was applied at 120 g / m ² on the surface of the surface coat layer formed on the release paper, and then dried at 120 ° C. for 2 minutes to form an inner layer having a thickness of 35 μm. A film was formed.

Then, a polyurethane elastomer solution for forming an adhesive layer is applied to the surface of the inner layer film formed on the release paper at 110 g / m ² and then dried at 120 ° C. for 2 minutes to form an adhesive layer having a thickness of 60 μm. did.

  With the heating roll set to a surface temperature of 75 ° C., the adhesive layer of the laminate forming the silver surface layer on the release paper thus formed was placed in contact with the slice surface of the fiber base sheet. Crimped. Then, after aging at 50 ° C. for 3 days, the release paper was peeled off to obtain a silver-tone artificial leather.

  And the polyurethane elastomer and silver-tone artificial leather which form a surface coat layer were evaluated as follows.

(Evaluation of dynamic viscoelasticity of polyurethane elastomer)
A test piece of polyurethane elastomer for forming the surface coat layer was prepared as a film having a thickness of 100 μm. And the storage elastic modulus G 'and loss elastic modulus G''of the test piece when measuring temperature was changed were measured using the viscoelasticity measuring apparatus (the product made by Rheology, DVE-V4). Measurement conditions are measurement modes: Tensile, displacement amplitude: 20 μm, frequency: 1 Hz, measurement temperature: −40 ° C. to 190 ° C., heating rate: 2 ° C./min, and ratio G ″ / loss elastic modulus G ″ to storage elastic modulus G ′ G ′ is the loss tangent (tan δ), and the temperature at which tan δ is maximum in the measured temperature range is defined as the glass transition temperature T _g from the graph showing the change in tan δ with respect to temperature.

(Evaluation of tensile modulus of polyurethane elastomer)
A test piece of polyurethane elastomer for forming the surface coat layer was prepared as a film having a thickness of 100 μm. And the temperature dependence of the tensile elasticity modulus of a polyurethane elastomer was measured in the range of 0-100 degreeC. As an example, FIG. 3 shows a graph of the temperature dependence of the tensile elastic modulus of MS3510, MS4510, MS5510, and MS6510 of “SMP”.

(Repairability evaluation)
On the surface coat layer of the resulting silver-tone artificial leather, scratches having a length of about 20 mm and a depth of about 0.03 mm were formed at the tip of the mechanical pencil. And after applying hot air of the hair dryer of temperature 80 degreeC for 3 minutes, it stood to cool naturally. The repair condition of scratches after natural cooling was determined according to the following criteria.
A: The scratch was disappeared.
B: Although the scratch was thin, the trace of the damaged part was confirmed.
C: Scratches were hardly repaired.

  The results are shown in Table 1 below.

[Example 2]
35% by mass of polyurethane elastomer with T _{g of} 65 ° C. instead of 35% by mass DMF solution of shape memory polyurethane elastomer with T _{g of} 55 ° C. (MS5510 of polyurethane-based shape memory polymer “SMP” manufactured by SMP Technologies) Using a DMF solution (MS6510 of polyurethane-based shape memory polymer “SMP” manufactured by SMP Technologies Inc.), a silver-tone artificial leather was obtained in the same manner as in Example 1, and evaluated in the same manner. The results are shown in Table 1.

[Example 3]
Instead of T _g 55 35 wt% DMF solution of ℃ of shape memory polyurethane elastomer ((Ltd.) MS5510 of SMP Technologies Corporation polyurethane based shape memory polymer "SMP"), T _g 45 35 wt% of ℃ polyurethane elastomer Using a DMF solution (MS4510 of polyurethane-based shape memory polymer “SMP” manufactured by SMP Technologies Co., Ltd.), a silver-tone artificial leather was obtained in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 1.

[Example 4]
35% by mass of T _{g of} 35 ° C. polyurethane elastomer instead of 35% by mass DMF solution of shape memory polyurethane elastomer with T _{g of} 55 ° C. (MS5510 of polyurethane-based shape memory polymer “SMP” manufactured by SMP Technologies) Using a DMF solution (MS3510 of polyurethane-based shape memory polymer “SMP” manufactured by SMP Technologies Inc.), a silver-tone artificial leather was obtained in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 1.

[Comparative example]
Instead of 35 _g DMF solution of shape memory polyurethane elastomer having a T _{g of} 55 ° C. (MS5510 of polyurethane-based shape memory polymer “SMP” manufactured by SMP Technologies, Inc.), T _g −40 having no shape memory Using a 35 mass% DMF solution of polyurethane elastomer at 0 ° C. (ME-8115LP manufactured by Dainichi Seika Co., Ltd.), a silver-tone artificial leather was obtained in the same manner as in Example 1 and evaluated in the same manner. The results are shown in Table 1.

[Example 5]
A fiber base sheet having a thickness of 0.6 mm similar to that used in Example 1 was prepared. And the silver surface layer was formed in the fiber base sheet by the dry surface forming method as described below.

A 35% by mass DMF solution of polycarbonate polyurethane elastomer was applied at 90 g / m ² on the release paper, and then dried at 120 ° C. for 2 minutes to form a surface coat layer film having a thickness of 25 μm.

Next, as a polyurethane elastomer solution for forming an inner layer on the surface of the coating film of the surface coating layer formed on the release paper, a shape memory with a T _{g of} 55 ° C. was used to form the surface coating layer in Example 1. A 35 mass% DMF solution of polyurethane elastomer was applied at 120 g / m ² and then dried at 120 ° C. for 2 minutes to form an inner layer film having a thickness of 35 μm.

Then, a polyurethane elastomer solution for forming an adhesive layer is applied to the surface of the inner layer film formed on the release paper at 110 g / m ² and then dried at 120 ° C. for 2 minutes to form an adhesive layer having a thickness of 60 μm. did.

  With the heating roll set to a surface temperature of 75 ° C., the adhesive layer of the laminate forming the silver surface layer thus formed on the release paper was placed in contact with the slice surface of the fiber base sheet. Crimped. Then, after aging at 50 ° C. for 3 days, the release paper was peeled off to obtain a silver-tone artificial leather. The resulting silver-tone artificial leather had a thickness of 700 μm.

  In the production of the above-mentioned artificial leather with silver, a raw material having a width of 1500 mm and a length of 40 m was continuously produced by a continuous production process, and then taken and stored in a roll state wound around a core material having a diameter of 76 mm. Then, after storage for about 14 days, a pressing mold was formed by repeating each turn around a portion corresponding to about 5 m of the first turn of the core material.

  The hot air of a hair dryer having a temperature of 80 ° C. was applied for 3 minutes to the part where the pressed mold of the artificial leather with silver was formed, and then naturally cooled. After natural cooling, the pressing mold disappeared.

  The leather-like sheet that self-repairs surface scratches and pressing molds by heating according to the present invention is preferably used as a material for skins such as bags, shoes, and clothing. In particular, it is preferably used as a skin material for children's heels such as school bags that are exposed to conditions that can be easily damaged depending on the mode of use.

DESCRIPTION OF SYMBOLS 1 Fiber base sheet 2 Adhesive layer 3,13 Inner layer 4,14 Surface coat layer 4a Scratch 13a Pressing type | mold 5,15 Silver surface layer

Claims (7)

A leather-like sheet in which a silver surface layer is laminated on the surface of a fiber base sheet,
The leather-like sheet, wherein the silver layer has a layer containing a shape memory polyurethane elastomer. The shape memory polyurethane elastomer has a glass transition temperature (T _g ) defined as a temperature indicating a peak value of a temperature dependence curve of a loss tangent (tan δ) at a frequency of 1 Hz, and is from 35 to 100 ° C. ^2. The leather-like sheet according to claim 1, which is a polyurethane elastomer having a temperature range of 25 ° C. or less and a change in tensile elastic modulus before and after the glass transition region of 1.0 × 10 ² times or more.   The leather-like sheet according to claim 1 or 2, wherein the silver layer has a laminated structure, and the layer containing the shape memory polyurethane elastomer is a surface coat layer disposed on the outermost layer of the silver layer. .   The leather-like sheet according to any one of claims 1 to 3, wherein the silver surface layer has a laminated structure, and the layer containing the shape memory polyurethane elastomer is disposed on an inner layer of the silver surface layer. The glass transition temperature (T _g ) defined as the temperature indicating the peak value of the temperature dependence curve of the loss tangent (tan δ) at a frequency of 1 Hz is 35 to 100 ° C., and the temperature width of the glass transition region is 25 ° C. or less. And forming a polyurethane elastomer film on the release paper to be a surface coat layer containing a polyurethane elastomer having a change in tensile elastic modulus of 1.0 × 10 ² times or more before and after the glass transition region. Forming a laminate in which a polymer elastic body film as an inner layer is further laminated;
Bonding the surface of the polymer elastic body film to be the inner layer of the laminate to the surface of the fiber base sheet via an adhesive layer,
After shaping in the region showing a rubbery elastic present the polyurethane elastomer coating to a temperature range higher than the T _g, further comprising a step of cooling to the region under illustrating a glassy state present in the T _g lower temperature region A method for producing a leather-like sheet. Forming a polymer elastic body film to be a surface coat layer constituting the silver surface layer on the release paper;
A glass transition temperature (T _g ) defined as a temperature indicating a peak value of a temperature dependence curve of a loss tangent (tan δ) at a frequency of 1 Hz is 35 to 100 ° C. A temperature range of the glass transition region is 25 ° C. or less, and a polyurethane elastomer film that is an inner layer containing a polyurethane elastomer having a tensile elastic modulus change of 1.0 × 10 ² times or more before and after the glass transition region is Forming a laminated body laminated on a polymer elastic body film to be a surface coat layer;
Bonding the laminate to the surface of the fiber base sheet via an adhesive layer,
After shaping in the region showing a rubbery elastic present the polyurethane elastomer coating to a temperature range higher than the T _g, further comprising a step of cooling to the region under illustrating a glassy state present in the T _g lower temperature region A method for producing a leather-like sheet. It is an external appearance restoration method of the leather-like sheet according to any one of claims 1 to 4,
Identifying a scratch or mold on the leather-like sheet;
The leather-like sheet appearance repair method which comprises a heating the identified flaws or mold to a temperature above the T _g of the shape memory polyurethane elastomer.

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