JP2021155866A - Artificial leather and method for producing the same - Google Patents

Abstract

To provide an artificial leather which has high followability to its shape and excellent shape retention when used for a complicated shape difficult to be molded in a conventional artificial leather, and which has little decrease in surface quality at the time of elongation.SOLUTION: There is provided an artificial leather comprising: a nonwoven fabric composed of ultrafine fibers which have an average single filament diameter of 1.0 μm or more and 10.0 μm or less and is made of a thermoplastic resin; and a polymeric elastomer, wherein a minimum value of a 40% circular modulus of the artificial leather is 30 N/cm or less, and a difference between a maximum value and the minimum value of the 40% circular modulus is 25 N/cm or more and 50 N/cm or less.SELECTED DRAWING: None

Description

The present invention comprises a non-woven fabric made of ultrafine fibers made of a thermoplastic resin and a polymer elastic body, and has high followability to the base material, particularly when used as a skin material for a base material having a complicated shape. It relates to artificial leather having excellent morphological retention and less deterioration of surface quality during stretching.

Natural leather-like artificial leather made of a non-woven fabric made of ultrafine fibers mainly made of thermoplastic resin and a polymer elastic body has excellent characteristics in comparison with natural leather such as high durability and uniformity of quality. .. Therefore, it is used not only as a material for clothing but also in various fields such as vehicle interior materials, interiors, shoes and clothing. Artificial leather has various required characteristics depending on the application, but when used as a skin material for a base material with a complicated shape such as the ceiling of a vehicle, wrinkles and tarmi do not occur, and it can follow the base material. Has been required to be excellent.

In response to the above problems, a method of obtaining an artificial leather having excellent followability to a base material has been proposed by adjusting the stress and modulus during elongation of the artificial leather (see Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 2003-02573 Japanese Unexamined Patent Publication No. 2016-186138 Japanese Unexamined Patent Publication No. 2013-194326

In the techniques disclosed in Patent Documents 1 to 3, by reducing the modulus of the artificial leather within a specific range, it is possible to obtain an artificial leather having excellent followability to the base material at the time of molding to some extent. However, an effective solution has not been obtained so far as an artificial leather that can be molded even on a base material having a more complicated shape, which is required with the expansion of applications of artificial leather. For example, when a known low modulus technique such as flexible processing is applied to the technique disclosed in Patent Document 1 in order to further reduce the modulus, the artificial leather slips out during the molding process. Not only was the graceful appearance spoiled, but the durability was also significantly inferior.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is that when it is used for a complicated shape that is difficult to mold with conventional artificial leather, it has high followability to the shape. It is an object of the present invention to provide artificial leather having excellent morphological retention and less deterioration of surface quality during stretching.

As a result of repeated studies by the present inventors to achieve the above object, the modulus of the artificial leather is not merely reduced, but is made into a structure having both a low direction and a high direction of the modulus to form a complicated shape. Even when used as the skin material of the base material, it can be molded without wrinkles or tarmi while there is little change in the appearance quality of the stretched part and the non-stretched part, and it also has morphological retention. Found to be excellent.

The present invention has been completed based on these findings, and the following inventions are provided according to the present invention.

That is, the artificial leather of the present invention is an artificial leather having an average single fiber diameter of 1 μm or more and 10 μm or less, a non-woven fabric made of ultrafine fibers made of a thermoplastic resin, and a polymer elastic body. The minimum value of the 40% circular modulus is 30 N / cm or less, and the difference between the maximum value and the minimum value of the 40% circular modulus is 25 N / cm or more and 50 N / cm or less.

According to a preferred embodiment of the artificial leather of the present invention, the nap coverage is 60% or more, and the retention of the nap coverage after stretching 40% in any one in-plane direction of the artificial leather is 70% or more. be.

According to a preferred embodiment of the artificial leather of the present invention, the tensile strength in any direction is 10 N / cm or more.

According to a preferred embodiment of the artificial leather of the present invention, the thermoplastic resin is made of a polyester resin, and the polyester contains 1 to 500 ppm of 1,2-propanediol.

According to a preferred embodiment of the artificial leather of the present invention, the biomass plastic degree defined by ISO16620 (2015) is 10% or more and 100% or less.

The method for producing artificial leather of the present invention comprises a non-woven fabric made of a thermoplastic resin composition and made of ultrafine fibers having an average single fiber diameter of 1 μm or more and 10 μm or less, and a sheet-like material containing a polymer elastic body as a constituent element. A half-cut surface is formed by half-cutting in the thickness direction, and at least the half-cut surface is ground from the obtained sheet-like material so that the thickness of the sheet-like material is 70% or less to form a raised sheet, and the raised sheet is formed. This is the method for producing artificial leather, wherein the artificial leather is stretched by 5% or more and 20% or less in the longitudinal direction thereof.

According to the present invention, it is possible to obtain artificial leather having high followability to the base material and excellent shape retention even when used as a skin material for a base material having a complicated shape. Further, the artificial leather of the present invention has a graceful appearance and a flexible tactile sensation similar to that of natural leather, and can be widely used from furniture, chairs and vehicle interior materials to clothing applications, and is particularly excellent as a base material. It is preferably used as a ceiling material for vehicles because of its ability to follow.

The artificial leather of the present invention has an average single fiber diameter of 1 μm or more and 10 μm or less, and is an artificial leather made of a non-woven fabric made of ultrafine fibers made of a thermoplastic resin and a polymer elastic body. It is an artificial leather in which the minimum value of% circular modulus is 30 N / cm or less, and the difference between the maximum value and the minimum value of 40% circular modulus is 25 N / cm or more and 50 N / cm or less.

The components thereof will be described in detail below, but the present invention is not limited to the scope described below as long as the gist thereof is not exceeded.

[Non-woven fabric]
The non-woven fabric according to the artificial leather of the present invention has an average single fiber diameter of 1 μm or more and 10 μm or less, and is made of ultrafine fibers made of a thermoplastic resin. As the thermoplastic resin, a polyester resin or a polyamide resin is preferably used from the viewpoint of durability, particularly mechanical strength, and it is more preferable to use a polyester resin having excellent heat resistance.

Examples of the polyester-based resin include polyethylene terephthalate, polytrimethylene terephthalate, polytetramethylene terephthalate, polycyclohexylenemethylene terephthalate, polyethylene-2,6-naphthalene dicarboxylate, and polyethylene-1,2-. Examples thereof include bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate and the like. Among them, polyethylene terephthalate, which is the most widely used, or a polyester copolymer mainly containing an ethylene terephthalate unit is preferably used.

When a polyester resin is used as the thermoplastic resin, 1,2-propanediol is derived from the polyester constituting the polyester resin in order to improve the heat resistance and abrasion resistance when thermoforming the artificial leather. It is preferable that the component of 1 to 500 ppm is contained.

The concentration of the 1,2-propanediol-derived component referred to here is determined by the total amount of 1,2-propanediol detected when the polyester is decomposed and analyzed by the method described in the section of Examples. Therefore, it is considered that the structure derived from 1,2-propanediol copolymerized in the polymer chain and the total amount of 1,2-propanediol mixed between the polymers. That is, this 1,2-propanediol may be partially copolymerized in the polyester main chain, and it is permissible that the 1,2-propanediol is contained as a simple substance without being copolymerized. When a polymer other than polyester is contained in the fiber, polyester is selectively selected by using a solvent such as 1,1,1,3,3,3-hexafluoro-2-propanol or orthochlorophenol. After extraction and distilling off the solvent, the concentration is determined by the method described in the section of Examples.

In addition, this thermoplastic resin can be used for various purposes, such as inorganic particles such as titanium oxide, a lubricant, a heat stabilizer, an ultraviolet absorber, a conductive agent, a heat storage agent, and an antibacterial agent, as long as the object of the present invention is not impaired. Agents and the like can be added.

The cross-sectional shape of the ultrafine fiber is preferably a round cross section from the viewpoint of processing operability, but polygonal shapes such as ellipse, flat and triangular, fan-shaped and cross-shaped, hollow type, Y-shaped, T-shaped, and U It is also possible to adopt a cross-sectional shape of a deformed cross section such as a mold.

Next, the average single fiber diameter of the ultrafine fibers according to the present invention is 1 μm or more and 10 μm or less. By setting the average single fiber diameter of the ultrafine fibers to 1.0 μm or more, preferably 1.5 μm or more, more preferably 2.0 μm or more, color development after dyeing, light resistance, friction fastness, and stability during spinning can be obtained. It has an excellent effect. On the other hand, by setting the thickness to 10.0 μm or less, preferably 6.0 μm or less, more preferably 5.0 μm or less, artificial leather having a fine and soft touch and excellent surface quality can be obtained.

In the present invention, the average single fiber diameter of ultrafine fibers is defined by taking a scanning electron microscope (SEM) photograph of an artificial leather cross section and randomly selecting 10 circular or nearly circular elliptical ultrafine fibers to obtain a single fiber diameter (single fiber diameter). It shall be calculated by measuring μm), calculating the arithmetic mean value of 10 lines, and rounding to the second digit after the decimal point. However, when ultrafine fibers with irregular cross sections are used, the cross-sectional area (μm ² ) of the single fibers is first measured, and the diameter when the cross section is regarded as a circle, that is, the equivalent circle diameter is calculated. The fiber diameter (μm) shall be determined.

Further, the artificial leather of the present invention has the above-mentioned non-woven fabric made of ultrafine fibers as a constituent element, that is, in the artificial leather, an aggregate of ultrafine fibers forms a non-woven fabric. By using a non-woven fabric, not only can a uniform and graceful appearance be obtained when the surface is brushed, but also artificial leather having a soft texture can be obtained.

As the form of the non-woven fabric, either a long-fiber non-woven fabric or a short-fiber non-woven fabric can be adopted, but a short-fiber non-woven fabric is preferable because the number of raised hairs on the product surface is large and an elegant appearance can be easily obtained.

The fiber length of the ultrafine fibers when made into a short-fiber non-woven fabric is preferably 25 to 90 mm. By setting the fiber length to 90 mm or less, good quality and texture can be obtained, and by setting the fiber length to 25 mm or more, a skin sheet having excellent wear resistance can be obtained. The fiber length is more preferably 35 to 80 mm, still more preferably 40 to 70 mm.

[Polymer elastic body]
The polymer elastic body constituting the artificial leather of the present invention plays a role of a binder for gripping the ultrafine fibers in the artificial leather. Therefore, it is preferable to use polyurethane, polyurethane, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), acrylic resin or the like as the polymer elastic body so that the artificial leather has a more flexible texture. Above all, it is more preferable to use polyurethane as a main component. By using polyurethane, it is possible to obtain artificial leather having a full feel, a leather-like appearance, and physical characteristics that can withstand actual use. The term "main component" as used in the present invention means that the mass of polyurethane is more than 50% by mass with respect to the mass of the entire polymer elastic body.

When polyurethane is used in the present invention, both an organic solvent-based polyurethane used in a state of being dissolved in an organic solvent and a water-dispersible polyurethane used in a state of being dispersed in water can be adopted. Further, as the polyurethane, a polyurethane obtained by reacting a polymer diol, an organic diisocyanate and a chain extender is preferably used.

Further, in the polymer elastic body, various additives such as pigments such as carbon black, flame retardant agents such as "phosphorus-based, halogen-based and inorganic-based", and "phenol-based, sulfur-based and phosphorus-based" are used depending on the purpose. Antioxidants such as "benzotriazole-based, benzophenone-based, salicylate-based, cyanoacrylate-based and oxalic acid anilide-based" UV absorbers, light stabilizers such as "hindered amine-based and benzoate-based", polycarbodiimide Hydrolysis-resistant stabilizers such as, plasticizers, anti-electricity agents, surfactants, coagulation modifiers, dyes and the like can be contained.

Generally, the content of the polymer elastic body in the artificial leather can be appropriately adjusted in consideration of the type of the polymer elastic body to be used, the method for producing the polymer elastic body, and the texture and physical properties. The content of the polymer elastic body is preferably 20% by mass or more and 50% by mass or less with respect to the mass of the non-woven fabric. By setting the content of the polymer elastic body to 20% by mass or more, more preferably 25% by mass or more, the abrasion resistance of the artificial leather can be improved. On the other hand, by setting the content of the polymer elastic body to 50% by mass or less, more preferably 45% by mass or less, still more preferably 40% by mass or less, the artificial leather can be made more flexible. can.

In the present invention, from the viewpoint of the soft texture and extensibility of the artificial leather, it is preferable that the mass of the polymer elastic body that grips the ultrafine fibers is small. More specifically, of the elastic polymer to be observed on the cut surface when cutting the artificial leather in the thickness direction, the cross-sectional area of the largest elastic polymer, it is 1000 .mu.m ² or more 5000 .mu.m ² or less preferable.

The largest cross-sectional area of the elastic polymer 5000 .mu.m ² or less, preferably when is 4000 .mu.m ² below, becomes artificial leather is flexible. On the other hand, when the cross-sectional area of the largest polymer elastic body is 1000 μm ² or more, preferably 1500 μm ² , the artificial leather has excellent wear resistance.

In the present invention, the cross-sectional area of the polymer elastic body is the largest of the polymer elastic bodies in 10 SEM images obtained by photographing a cross section cut in the thickness direction of artificial leather with a scanning electron microscope (SEM) at a magnification of 500 times. It refers to the arithmetic average value of the numerical values of a total of 10 images calculated by calculating the cross-sectional area (μm ^2).

[Artificial leather]
The artificial leather of the present invention is composed of the above-mentioned non-woven fabric and a polymer elastic body, and preferably has fluff on the surface. When the fluff is present on the surface, the fluff may be present only on the surface of the artificial leather, and it is permissible to have the nap on both sides. From the viewpoint of the design effect, it is more preferable that the surface of the fluff has a fluff length and directional flexibility to the extent that a so-called finger mark is left, that is, a mark is left by changing the direction of the fluff when traced with a finger.

More specifically, in order to make the finger marks clear, the nap length on the surface is preferably 100 μm or more, more preferably 150 μm or more, and even more preferably 200 μm or more. On the other hand, in order to suppress fiber loss during friction, it is preferably 400 μm or less, and more preferably 350 μm or less. The length of the fluff on the surface is determined by photographing the cross section of the artificial leather with a scanning electron microscope (SEM) at a magnification of 50 times with the fluff of the artificial leather turned upside down using a lint brush or the like. ) Is measured at 10 points and the average value is calculated.

In the artificial leather of the present invention, the ratio of the fluff of the artificial leather covering the surface (fluff coverage) is preferably 60% or more, and more preferably 70% or more. When the fluff coverage is 60% or more, the surface of the artificial leather has a uniform and graceful appearance.

On the other hand, from the viewpoint of dispersibility of fluff, the fluff coverage is preferably 95% or less, and more preferably 90% or less.

Further, the artificial leather of the present invention preferably has a retention rate of fluff coverage of 70% or more, more preferably 75% or more after being stretched by 40% in any one in-plane direction of the artificial leather. , 80% or more is more preferable. The retention rate of the nap rate at 40% elongation is obtained by dividing the nap rate at 40% elongation by the nap rate under normal conditions, and the retention rate of the nap rate at 40% extension is 70%. The above is preferable because the difference in appearance quality between the portion where the artificial leather is greatly stretched at the time of molding and the portion where the artificial leather is not stretched becomes small.

In the present invention, the nap coverage under normal conditions and at 40% elongation is measured as follows. The fluff coverage in the normal state was magnified at an observation magnification of 30 to 90 times on the nap surface so that the presence of naps could be seen by SEM, and the total area of the naps per ^{9 mm 2 total area was measured using image analysis software.} The ratio was calculated and used as the nap coverage. The ratio of the total area is binarized by setting the threshold value of 100 for the napped part and the non-raised part using, for example, the image analysis software "ImageJ" developed by the National Institutes of Health for the captured SEM image. It can be calculated by doing. Further, in the calculation of the napped coverage rate, when a substance other than napped hair is calculated as napped hair and has a great influence on the napped hair coverage rate, the image is manually edited and that portion is calculated as a non-fluffed portion.

As the image analysis system, the above-mentioned image analysis software "ImageJ" is exemplified, but if the image analysis system is composed of image processing software having a function of calculating a predetermined pixel area ratio, the image analysis software Not limited to "ImageJ".

Regarding the nap coverage after stretching 40% in any in-plane direction of the artificial leather, the artificial leather is stretched 40% in any direction, and the shape is maintained by using tape etc. It was measured and calculated in the same way.

The artificial leather of the present invention has a thickness of 0.2 mm or more measured by "6.1.1 A method" of "6.1 thickness (ISO method)" of JIS L1913: 2010 "General non-woven fabric test method". The range is preferably 1.0 mm or less. By setting the thickness of the artificial leather to 0.2 mm or more, more preferably 0.3 mm or more, and further preferably 0.4 mm or more, not only the workability at the time of manufacturing is excellent, but also the texture is excellent. It becomes a thing. On the other hand, by setting the thickness to 1.0 mm or less, more preferably 0.9 mm or less, still more preferably 0.8 mm or less, a flexible artificial leather having excellent moldability can be obtained.

The artificial leather of the present invention has an in-plane tensile strength (tensile strength) measured by "6.3.1 Tensile strength and elongation (ISO method)" of JIS L1913: 2010 "General non-woven fabric test method". When it is 10 N / cm, more preferably 12 N / cm or more, and further preferably 15 N / cm or more in any measurement direction, the morphological stability and durability of the artificial leather, particularly the breakage due to aged deterioration of the stretched portion during molding, is caused. It is preferable because it can be suppressed.

The term "arbitrary in-plane direction" as used herein means that artificial leather is randomly measured in four in-plane directions, and all of them show measured values within the above range. The four directions in the plane to be measured are the four directions obtained by making an angle of 45 degrees each, that is, the directions forming angles of 0 degrees, 45 degrees, 90 degrees, and 135 degrees with respect to the reference line in the plane. , It is preferable that all of them have a value within the above range. The measurement is performed three or more times in each direction.

In the artificial leather of the present invention, it is important that the minimum value of the 40% circular modulus is 30 N / cm or less from the viewpoint of moldability. By having a portion of 40% circular modulus of 30 N / cm or less, more preferably 25 N / cm or less, still more preferably 20 N / cm or less, it has high followability to bent portions and the like when stretched during molding, and wrinkles. And the occurrence of wrinkles can be prevented.

Further, it is important that the difference between the maximum value and the minimum value of the 40% circular modulus of the artificial leather of the present invention is 25 N / cm or more and 50 N / cm or less. By setting the difference between the maximum value and the minimum value to 25 N / cm or more, preferably 30 N / cm or more, the portion that follows the bent portion during molding can be held in an stretched state, and as a result, changes over time. Not only can it suppress the occurrence of wrinkles and tarmi due to, but it can also suppress the deterioration of surface quality due to slipping during stretching.

Further, by setting the difference between the maximum value and the minimum value of the 40% circular modulus to 50 N / cm or less, preferably 40 N / cm or less, it is possible to suppress distortion and wrinkles during molding.

The maximum and minimum values of the 40% circular modulus of artificial leather referred to in the present invention are the maximum and minimum values of the 40% circular modulus of artificial leather measured and calculated by the following method. To tell.
(1) Cut out a 150 mmφ circular test piece from artificial leather.
(2) At the center of the test piece, mark a reference point between 100 mm in one direction for each piece.
(3) With an Instron type tensile tester, the grip interval is 100 mm, the tensile speed is 200 mm / min, and the modulus at 40% elongation is measured.
(4) The measurements of (1) to (3) are sampled in each direction at an angle of 0 degree, 45 degree, 90 degree, and 135 degree with respect to the reference line arbitrarily drawn on the artificial leather. For the arithmetic average value of the values measured for three or more samples, obtain the value in each direction and use it as the maximum value and the minimum value.

Further, the artificial leather of the present invention preferably has a biomass plastic degree of 10% or more as defined by ISO16620 (2015) from the viewpoint of carbon neutrality. From the viewpoint of reducing the environmental load, the biomass plastic degree is more preferably 15% or more, and further preferably 20% or more.

[Manufacturing method of artificial leather]
The method for producing artificial leather of the present invention comprises a non-woven fabric made of a thermoplastic resin composition and made of ultrafine fibers having an average single fiber diameter of 1 μm or more and 10 μm or less, and a sheet-like material containing a polymer elastic body as a constituent element. A half-cut surface is formed by half-cutting in the thickness direction, and at least the half-cut surface is ground from the obtained sheet-like material so that the thickness of the sheet-like material is 70% or less to form a raised sheet, and the raised sheet is formed. Is a method for producing artificial leather, which extends 5% or more and 20% or less in the longitudinal direction thereof.

The details of each of these steps will be described below.

<Step of producing a non-woven fabric by entwining ultrafine fiber-expressing fibers>
In this step, a non-woven fabric is produced by entwining ultrafine fiber-expressing fibers made of two or more types of thermoplastic resins having different solubilitys in a solvent.

As the ultrafine fiber-expressing type fiber, thermoplastic resins having different solvent solubility are designated as a sea part (easily soluble polymer) and an island part (poorly soluble polymer), and the sea part is dissolved and removed by using a solution or the like. It is preferable to use a sea-island type composite fiber having an island portion as an ultrafine fiber. By using the sea-island type composite fiber, it is possible to provide an appropriate void between the islands, that is, between the ultrafine fibers inside the fiber bundle when removing the sea part, which is preferable from the viewpoint of the texture and surface quality of the artificial leather. .. As a method for spinning ultrafine fiber-expressing fibers having a sea-island type composite structure, a method using a sea-island type composite base and a polymer mutual arrangement in which the sea part and the island part are mutually arranged and spun is a uniform single method. It is preferable from the viewpoint that ultrafine fibers having a fiber fineness can be obtained.

As the easily soluble polymer, polyethylene, polypropylene, polystyrene, copolymerized polyester obtained by copolymerizing sodium sulfoisophthalic acid, polyethylene glycol, or the like, polylactic acid, or the like can be used. Among them, polystyrene and copolymerized polyester are preferably used from the viewpoints of yarn-making property, easy elution property and the like.

When a sea-island type composite fiber is used in the method for producing artificial leather of the present invention, it is preferable to use a sea-island type composite fiber having an island strength of 2.5 cN / dtex or more. When the strength of the island portion is 2.5 cN / dtex or more, more preferably 2.8 cN / dtex or more, still more preferably 3.0 cN / dtex or more, the abrasion resistance of the artificial leather can be improved.

When the sea-island type composite fiber is used in the present invention, the strength of the island portion of the sea-island type composite fiber shall be calculated by the following method.
(1) Bundle 10 sea-island type composite fibers with a length of 20 cm.
(2) After dissolving and removing the sea part from the sample of (1), it is air-dried.
(3) Grasp length 5 cm, tensile speed 5 cm / min in "8.5.1 Standard time test" of "8.5 Tensile strength and elongation" of JIS L1013: 2010 "Chemical fiber filament yarn test method" , Test 10 times under the condition of load 2N (N = 10).
(4) The value obtained by rounding off the arithmetic mean value (cN / dtex) of the test results obtained in (3) to the second decimal place is taken as the strength of the island part of the sea-island type composite fiber.

Next, after the spun ultrafine fiber-expressing fibers are opened, a fiber web is formed by a cloth wrapper or the like, and the fibers are entangled to obtain a non-woven fabric. As a method of entwining the fiber webs to obtain a non-woven fabric, a needle punching process, a water jet punching process, or the like can be used.

As the form of the non-woven fabric, either the short-fiber non-woven fabric or the long-fiber non-woven fabric can be used as described above, but the short-fiber non-woven fabric has more fibers facing the thickness direction of the artificial leather than the long-fiber non-woven fabric. A high degree of fineness can be obtained on the surface of the artificial leather when it is raised.

When a short-fiber non-woven fabric is used as the non-woven fabric, the obtained ultrafine fiber-expressing fiber is preferably crimped, cut to a predetermined length to obtain raw cotton, and then opened, laminated, and entangled. To obtain a short fiber non-woven fabric. A known method can be used for the crimping process and the cutting process.

<Step of applying an aqueous solution of a water-soluble resin to a non-woven fabric>
In this step, the non-woven fabric is impregnated with an aqueous solution of a water-soluble resin and dried at 110 ° C. or higher to impart the water-soluble resin.

As the water-soluble resin, polyvinyl alcohol is preferably used from the viewpoint of easy removal in a later step, and polyvinyl alcohol having a saponification degree of 80% or more is preferably used from the viewpoint of processing stability.

Examples of the method of applying the water-soluble resin to the non-woven fabric include a method of impregnating the non-woven fabric with an aqueous solution of the water-soluble resin and drying the non-woven fabric. The concentration of the aqueous solution of the water-soluble resin is preferably 1% or more and 20% or less.

By applying the water-soluble resin to the non-woven fabric, not only the fibers are fixed and the dimensional stability is improved, but also the water-soluble resin is unevenly distributed on both surface layers of the non-woven fabric due to migration during drying.

The amount of the water-soluble resin applied is preferably 10% by mass or more and 60% by mass or less with respect to the non-woven fabric immediately before application. By setting the imparting amount to 10% by mass or more, preferably 15% by mass or more, more preferably 20% by mass or more, a large amount of water-soluble resin is unevenly distributed on the surface layer portion, and the ultrafine fibers and the polymer elastic body are adhered to each other. The area becomes smaller. Further, by setting the applied amount to 60% by mass or less, preferably 50% by mass or less, more preferably 40% by mass or less, artificial leather having good processability and good physical properties such as abrasion resistance can be obtained.

The drying temperature of the water-soluble resin is 110 ° C. or higher, preferably 120 ° C. or higher. By setting the temperature to 110 ° C. or higher, the water-soluble resin can be sufficiently migrated.

<Step of applying a polymer elastic body after expressing ultrafine fibers from ultrafine fiber-expressing fibers>
In this step, the sheet obtained in the above step is treated with a solvent to express ultrafine fibers having an average fiber diameter of 1 μm or more and 10 μm or less, and then the sheet is impregnated with a solvent solution of a polymer elastic material. The step of solidifying and imparting a polymer elastic body, or the sheet obtained in the step (2) above is impregnated with a solvent solution of a polymer elastic body containing polyurethane as a main component and solidified to contain polyurethane as a main component. After the polymer elastic body to be added is applied, the sheet is treated with a solvent to develop ultrafine fibers having an average fiber diameter of 1 μm or more and 10 μm or less.

The polymer elastic body may be imparted to the sheet before the ultrafine fibers are expressed from the ultrafine fiber-expressing fibers, or after the ultrafine fibers are expressed from the ultrafine fiber-expressing fibers.

The ultrafine fiber expression treatment can be performed by immersing a non-woven fabric made of a sea-island type composite fiber in a solvent to dissolve and remove the sea portion of the sea-island type composite fiber.

When the ultrafine fiber-expressing fiber is a sea-island type composite fiber, an organic solvent such as toluene or trichlorethylene can be used as the solvent for dissolving and removing the sea part when the sea part is polyethylene, polypropylene or polystyrene. When the sea part is a copolymerized polyester or polylactic acid, an alkaline aqueous solution such as sodium hydroxide can be used. Further, when the sea part is a water-soluble thermoplastic polyvinyl alcohol-based resin, hot water can be used.

As a method of impregnating the sheet with the polymer elastic body and solidifying it, there is a method of impregnating the sheet with a solution of the polymer elastic body and then performing wet coagulation or dry coagulation. Method can be selected.

As the solvent used when imparting polyurethane as a polymer elastic body, N, N'-dimethylformamide, dimethyl sulfoxide and the like are preferably used. Further, an aqueous dispersion type polyurethane liquid in which polyurethane is dispersed as an emulsion in water may be used.

As described above, the water-soluble resin is unevenly distributed on both surface layer sides of the sheet before the polymer elastic body is applied, so that the polymer elastic body is unevenly distributed on the inner layer part of the sheet and solidifies. It becomes. Further, on the inner layer side of the non-woven fabric containing less water-soluble resin, the ultrafine fibers and the polymer elastic body are firmly adhered to each other. On the other hand, on both surface layer sides of the non-woven fabric containing a large amount of water-soluble resin, the polymer elastic body adheres to the ultrafine fibers from above the water-soluble resin, so that the adhesion between the ultrafine fibers and the polymer elastic body is also weak.

<Half-cutting process>
In this step, the sheet obtained in the above step is cut in half in the thickness direction. The half-cut processing may be performed by a known processing such as a band knife type slicer, as long as it can be half-cut at the center in the sheet thickness direction.

<Grinding process>
In this step, at least the half-cut surface is ground and raised so that the thickness after grinding is 70% or less of the thickness of the sheet obtained in the above step.

The grinding process can be performed by a method of grinding using sandpaper, a roll sander, or the like. The grinding process can be applied to only one surface of the artificial leather or to both sides, but at least the half-cut surface is ground.

Compared to the non-half-cut surface (corresponding to the above-mentioned surface layer part), the semi-cut surface (corresponding to the above-mentioned inner layer part) has the ultrafine fibers and the polymer elastic body adhered more firmly, and at least the half-cut surface is ground to obtain the sheet. It can be made flexible.

The grinding process is performed so that the thickness of the raised sheet after grinding is 70% or less, preferably 65% or less, and preferably 60% or less with respect to the thickness of the sheet after half-cutting. By making the thickness of the brushed sheet after grinding 70% or less of the thickness of the sheet after half-cutting, many half-cut surfaces where the ultrafine fibers and the polymer elastic body are firmly adhered are ground to make the sheet flexible. Not only can this be done, spots during grinding are suppressed, the raised surface of the sheet becomes uniform, and the appearance is graceful.

Prior to the grinding process, a lubricant such as a silicone emulsion can be applied to the surface of the sheet. Further, it is preferable to apply an antistatic agent before the grinding process because the grinding powder generated from the seat leather by grinding is less likely to be deposited on the sandpaper.

<Step of extending in the longitudinal direction>
In this step, the raised sheet obtained in the above step is stretched by 5% or more and 20% or less in the longitudinal direction.

Stretching 5% or more, preferably 7% or more, more preferably 10% or more in the longitudinal direction increases only the modulus in the longitudinal direction of the seat, so that the artificial leather has both a high direction and a low direction of the modulus. ..

Further, in order to suppress breakage of the sheet, it is preferably 20% or less, and more preferably 15% or less.

The stretching treatment can be carried out by a method such as stretching the sheet in the longitudinal direction in a high-temperature bath, and when the dyeing treatment described later is performed, it can be carried out at the same time as the dyeing.

The artificial leather of the present invention is preferably dyed. Examples of this dyeing treatment include liquid flow dyeing using a jigger dyeing machine or liquid flow dyeing machine, dyeing treatment such as thermosol dyeing using a continuous dyeing machine, roller printing, screen printing, inkjet printing, and sublimation. It is possible to use a printing treatment on the napped surface by printing, vacuum sublimation printing, or the like. Above all, it is preferable to use a liquid flow dyeing machine in terms of quality and quality because a flexible texture can be obtained. Further, if necessary, various resin finishing processes can be applied after dyeing.

Further, the surface of the artificial leather can be designed as needed. For example, post-processing such as perforation and other drilling, embossing, laser processing, pinsonic processing, and printing can be performed.

Next, the artificial leather of the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. Next, the evaluation method used in the examples and the measurement conditions thereof will be described. However, in the measurement of each physical property, if there is no particular description, the measurement is performed based on the above method.

[Measurement method and processing method for evaluation]
(1) 40% circular modulus of artificial leather:
A tensile tester manufactured by Instron, "Model: 3343" was used, and the measurement was performed according to the above method.

(2) In-plane tensile strength of artificial leather:
A tensile tester manufactured by Instron, "Model: 3343" was used, and the measurement was performed according to the above method.

(3) Content of components derived from 1,2-propanediol in polyester:
First, a 1000 μg / ml aqueous solution of 1,2-butanediol was prepared and used as an internal standard solution A. Weigh 0.1 g of the sample into a vial, add 0.015 ml of internal standard solution A and 1 ml of ammonia water to the vial, seal tightly, heat at a temperature of 150 ° C. for 3 hours, and then allow to cool to room temperature (25 ° C.). bottom. Subsequently, 2 ml of methanol and 2.0 g of terephthalic acid were added, and the mixture was shaken for 15 minutes and centrifuged at 4000 G for 3 minutes. Take out the supernatant, measure it with a gas chromatograph (5890 series II manufactured by Hewlett-Packard, injection port: split / splitless injection port, detector: hydrogen flame ionization detector) under the following setting conditions, and use the calibration curve described later. The content was determined.
・ Injector temperature: 220 ℃
-Column head pressure: 20 psi
-Carrier gas: Helium-Sample introduction method: Division (Linear flow velocity 25 ml / min)
-Partition purge: Helium 3.0 ml / min-Sample introduction amount: 1.0 μl
・ Detector temperature: 220 ℃
-Gas flow rate: Hydrogen 40 ml / min, Air 400 ml / min, Nitrogen 40 ml / min-Oven temperature rise start temperature: 60 ° C (holding time 2 minutes)
・ Oven temperature rise stop temperature: 220 ° C (holding time 2 minutes)
-Oven heating rate: 20 ° C / min (straight slope).

The calibration curve of 1,2-propanediol was prepared by the following procedure. After preparing a 1000 μg / ml aqueous solution of 1,2-propanediol to prepare the standard mother liquor B, 0.003 to 0.08 ml of the standard mother liquor B and 0.025 ml of the internal standard solution A were added to a 5 ml volumetric flask, and a mixed solvent ( Seven kinds of standard solution C prepared with methanol: purified water = 2: 1, containing 1.1% ethylene glycol) were prepared by changing the amount of standard mother liquor B. The amount of standard mother liquor B to be added is selected so that the concentration of 1,2-propanediol is sufficient for measuring the sample. The prepared standard solution C was measured by gas chromatography under the above conditions, and then the peak area ratio of the obtained 1,2-propanediol and the internal standard substance and the 1,2-propanediol in the standard solution C were added. A calibration curve of 1,2-propanediol was prepared by plotting the concentration ratio of the internal standard substance on a graph.

(4) Normal nap coverage of artificial leather:
In the measurement of the nap coverage, "VW-9000 type" manufactured by KEYENCE CORPORATION was used as a scanning electron microscope, and "ImageJ" was used as an image analysis software.

(5) Standing coverage after stretching 40% in any in-plane direction of artificial leather:
A test piece of 2 cm in length and 5 cm in width was cut out from artificial leather, stretched until the width was 7 cm, and then attached on a double-sided tape on a mount to prepare a sample at 40% stretch. Except for using this sample, the measurement was carried out in the same manner as the nap coverage under normal conditions.

(6) Surface quality when molding artificial leather A test piece of vertical 10 cm x horizontal 10 cm is cut out from the artificial leather, covered with a curved surface of a plastic hemisphere with a radius of 5 cm, and from the cross-sectional side of the hemisphere until wrinkles on the curved surface disappear. The surface quality at the time when the wrinkles on the curved surface disappeared by pulling was evaluated.

The evaluation was made by 10 healthy adults as evaluators by visual and sensory evaluation as shown in the following ○ △ ×, and the most common evaluation was the appearance quality. Good levels in the present invention are "◯" and "Δ".
◯: There is no or slight difference from the normal state △: The feeling of fineness is slightly inferior to that of the normal state ×: The feeling of fineness is significantly inferior to that of the normal state, or there are wrinkles and tarmi [Example 1]
<Step of producing a non-woven fabric by entwining ultrafine fiber-expressing fibers>
Polyethylene terephthalate (PET A), which has an intrinsic viscosity (IV) of 0.73 as an island component and is composed of ethylene glycol derived from biomass resources and contains 15 ppm of a 1,2-propanediol component, is used, and polystyrene with an MFR of 65 is used as a sea component. Using a sea-island type composite mouthpiece with 16 islands / hole, the spinning temperature is 285 ° C, the island / sea mass ratio is 80/20, the discharge rate is 1.2 g / min / hole, and the spinning speed is Melt spinning was performed under the condition of 1100 m / min. Then, it was stretched 2.8 times in an oil bath for spinning at a temperature of 90 ° C., crimped using a push-in crimping machine, and then cut to a length of 51 mm to have a single fiber fineness. Obtained raw cotton of 3.8 dtex sea-island type composite fiber.

Next, using the above-mentioned raw cotton of the sea-island type composite fiber, a laminated web is formed through a card and cross wrapper process, and needle punching is performed with a punch number of ^{2500 lines / cm 2 , and the basis weight is 450 g / m 2} . , A non-woven fabric having a thickness of 2.0 mm was obtained.

<Step of applying an aqueous solution of a water-soluble resin to a non-woven fabric>
The non-woven fabric obtained as described above is shrink-treated with hot water at a temperature of 96 ° C., impregnated with a 5% by mass PVA (polyvinyl alcohol) aqueous solution having a saponification degree of 88%, and then squeezed with a roll. The PVA was dried while migrating with hot air at a temperature of 120 ° C. for 10 minutes to obtain a sheet with PVA having a PVA mass of 27 mass% with respect to the mass of the non-woven fabric.

<Step of applying a polymer elastic body after expressing ultrafine fibers from ultrafine fiber-expressing fibers>
By immersing the sheet with PVA obtained as described above in trichlorethylene and squeezing and compressing it with mangle 10 times, the sea components are dissolved and removed and the sheet with PVA is compressed to obtain an ultrafine fibrous non-woven fabric. A sheet with desea PVA made of PVA was obtained. This sheet with desea PVA was immersed in a DMF (dimethylformamide) solution of polyurethane adjusted to a solid content concentration of 12.0%, squeezed with a roll, and then the polyurethane was solidified in an aqueous solution having a DMF concentration of 30%. Then, PVA and DMF were removed with hot water and dried with hot air at a temperature of 110 ° C. for 10 minutes to obtain a sheet with polyurethane having a thickness of 1.5 mm and a polyurethane mass of 30% by mass with respect to the mass of the non-woven fabric. ..

<Half-cutting process>
The polyurethane-coated sheet obtained as described above was cut in half vertically in the thickness direction to obtain a half-cut sheet having a thickness of 0.75 mm.

<Grinding process>
The half-cut surface of the half-cut sheet obtained as described above was ground 0.30 mm from the surface layer with sandpaper count 180 endless sandpaper to form a raised surface, and a raised sheet having a thickness of 0.45 mm was obtained.

<Step of extending in the longitudinal direction>
The brushed sheet obtained as described above was dyed with a black dye under a temperature condition of 120 ° C. using a liquid flow dyeing machine, and at the same time, the brushed sheet was stretched by 10% in the longitudinal direction and reduced and washed. Later, it was dried to obtain artificial leather. The artificial leather having an average short fiber diameter of 4.4 μm, a thickness of 0.5 mm, a grain size of 140 g / m ² and a biomass plasticity of 22% has excellent moldability, and is a stretched portion. There was little difference in the appearance quality of the non-stretched portion, and it had a good appearance. The results are shown in Table 1.

[Example 2]
<Step of producing a non-woven fabric by entwining ultrafine fiber-expressing fibers>
Using the same raw cotton as in Example 1, ^{a non-woven fabric having a basis weight of 390 g / m 2} and a thickness of 1.7 mm was obtained.

<Step of applying an aqueous solution of a water-soluble resin to a non-woven fabric-Step of applying a polymer elastic body>
A sheet with polyurethane having a thickness of 1.3 mm and a polyurethane mass of 30% by mass with respect to the mass of the nonwoven fabric was obtained in the same manner as in claim 1 except that the nonwoven fabric obtained as described above was used.

<Half-cutting process>
The polyurethane-coated sheet obtained as described above was cut in half vertically in the thickness direction to obtain a half-cut sheet having a thickness of 0.65 mm.

<Grinding process>
The half-cut surface of the half-cut sheet obtained as described above was ground 0.20 mm from the surface layer with endless sandpaper having a sandpaper count of 180 to form a raised surface, and a raised sheet having a thickness of 0.45 mm was obtained.

<Step of extending in the longitudinal direction>
The brushed sheet obtained as described above was dyed with a black dye under a temperature condition of 120 ° C. using a liquid flow dyeing machine, and at the same time, the brushed sheet was stretched by 10% in the longitudinal direction and reduced and washed. Later, it was dried to obtain artificial leather. The obtained artificial leather having an average short fiber diameter of 4.4 μm, a thickness of 0.5 mm, a grain size of 140 g / m ² and a biomass plasticity of 22% has excellent moldability and is a stretched portion. There was little difference in the appearance quality of the non-stretched part, and it had a good appearance. The results are shown in Table 1.

[Example 3]
<Process of entwining ultrafine fiber-expressing fibers to produce non-woven fabric-process of grinding>
A brushed sheet having a thickness of 0.45 mm was obtained in the same manner as in Example 1.

<Step of extending in the longitudinal direction>
An artificial leather having a thickness of 0.5 mm was obtained in the same manner as in Example 1 except that the elongation rate in the longitudinal direction was set to 6%. The artificial leather having an average short fiber diameter of 4.4 μm, a thickness of 0.5 mm, a grain size of 140 g / m ² and a biomass plasticity of 22% has excellent moldability, and is a stretched portion. There was little difference in the appearance quality of the non-stretched portion, and it had a good appearance. The results are shown in Table 1.

[Example 4]
<Step of producing a non-woven fabric by entwining ultrafine fiber-expressing fibers>
In the same manner as in Example 1, ^{a non-woven fabric having a basis weight of 450 g / m 2} and a thickness of 2.0 mm was obtained.

<Step of applying an aqueous solution of a water-soluble resin to a non-woven fabric>
In the same manner as in Example 1, a sheet with PVA having a PVA mass of 27% by mass with respect to the mass of the non-woven fabric was obtained.

<Step of applying a polymer elastic body after expressing ultrafine fibers from sea-island type composite fibers>
A sheet with polyurethane having a thickness of 1.5 mm was obtained in the same manner as in Example 1 except that the mass of polyurethane was set to 40% by mass with respect to the mass of the non-woven fabric.

<Half-cutting process>
The polyurethane-coated sheet obtained as described above was cut in half vertically in the thickness direction to obtain a half-cut sheet having a thickness of 0.75 mm.

<Grinding process>
The half-cut surface of the half-cut sheet obtained as described above was ground 0.30 mm from the surface layer with sandpaper count 180 endless sandpaper to form a raised surface, and a raised sheet having a thickness of 0.45 mm was obtained.

<Step of extending in the longitudinal direction>
The brushed sheet obtained as described above was dyed with a black dye under a temperature condition of 120 ° C. using a liquid flow dyeing machine, and at the same time, the brushed sheet was stretched by 10% in the longitudinal direction and reduced and washed. Later, it was dried to obtain artificial leather. The artificial leather having an average short fiber diameter of 4.4 μm, a thickness of 0.5 mm, a grain size of 150 g / m ² and a biomass plasticity of 19% has excellent moldability, and is a stretched portion. There was little difference in the appearance quality of the non-stretched portion, and it had a good appearance. The results are shown in Table 1.

[Example 5]
<Step of producing a non-woven fabric by entwining ultrafine fiber-expressing fibers>
Similar to Example 1 except that polyethylene terephthalate (PET B) having an intrinsic viscosity (IV) of 0.73 and containing petroleum-derived ethylene glycol and containing no 1,2-propanediol component was used as the island component. A non-woven fabric having a grain size of 450 g / m ^{2 and a thickness of 2.0 mm was obtained.}

<Step of applying an aqueous solution of water-soluble resin to non-woven fabric-step of stretching in the longitudinal direction>
An artificial leather was obtained in the same manner as in Example 1 except that the above-mentioned non-woven fabric was used. The artificial leather having an average short fiber diameter of 4.4 μm, a thickness of 0.5 mm, a grain size of 140 g / m ² and a biomass plasticity of 0% has excellent moldability, and is a stretched portion. There was little difference in the appearance quality of the non-stretched part, and it had a good appearance. The results are shown in Table 1.

[Comparative Example 1]
<Step of making a non-woven fabric by entwining ultrafine fiber-expressing fibers-step of half-cutting>
A half-cut sheet having a thickness of 0.75 mm was obtained in the same manner as in Example 1.

<Grinding process>
The anti-half-cut surface of the half-cut sheet obtained as described above was ground 0.30 mm from the surface layer with sandpaper count 180 endless sandpaper to form a raised surface, and a brushed sheet having a thickness of 0.45 mm was obtained. ..

<Step of extending in the longitudinal direction>
The brushed sheet obtained as described above was dyed with a black dye under a temperature condition of 120 ° C. using a liquid flow dyeing machine, and at the same time, the brushed sheet was stretched by 10% in the longitudinal direction and reduced and washed. Later, it was dried to obtain artificial leather. The obtained artificial leather having an average short fiber diameter of 4.4 μm, a thickness of 0.5 mm, a grain size of 140 g / m ² and a biomass plastic degree of 22% has wrinkles during molding, and the appearance of the stretched portion is further generated. There was a large change in quality and the appearance was uneven. The results are shown in Table 1.

[Comparative Example 2]
<Step of producing a non-woven fabric by entwining ultrafine fiber-expressing fibers>
Using the same raw cotton as in Example 1, ^{a non-woven fabric having a basis weight of 330 g / m 2} and a thickness of 1.5 mm was obtained.

<Step of applying an aqueous solution of a water-soluble resin to a non-woven fabric-Step of applying a polymer elastic body>
A sheet with polyurethane having a thickness of 1.1 mm and a polyurethane mass of 30% by mass with respect to the mass of the nonwoven fabric was obtained in the same manner as in claim 1 except that the nonwoven fabric obtained as described above was used.

<Half-cutting process>
The polyurethane-coated sheet obtained as described above was cut in half vertically in the thickness direction to obtain a half-cut sheet having a thickness of 0.55 mm.

<Grinding process>
The half-cut surface of the half-cut sheet obtained as described above was ground 0.10 mm from the surface layer with sandpaper count 180 endless sandpaper to form a raised surface, and a raised sheet having a thickness of 0.45 mm was obtained.

<Step of extending in the longitudinal direction>
The brushed sheet obtained as described above was dyed with a black dye under a temperature condition of 120 ° C. using a liquid flow dyeing machine, and at the same time, the brushed sheet was stretched by 3% in the longitudinal direction and reduced and washed. Later, it was dried to obtain artificial leather. The difference between the maximum and minimum values of 40% circular modulus for artificial leather with an average short fiber diameter of 4.4 μm, a thickness of 0.5 mm, a grain of 140 g / m ^{2 and a biomass plasticity of 22%.} Was small, and biomass was generated during molding, which was inferior in moldability as compared with the artificial leather of Example 1. The results are shown in Table 1.

Claims (6)

An artificial leather made of a thermoplastic resin composition and containing a non-woven fabric made of ultrafine fibers having an average single fiber diameter of 1 μm or more and 10 μm or less and a polymer elastic body as constituent elements, which is a 40% circular modulus of the artificial leather. Artificial leather having a minimum value of 30 N / cm or less and a difference between the maximum value and the minimum value of a 40% circular modulus of 25 N / cm or more and 50 N / cm or less. The artificial leather according to claim 1, wherein the nap coverage is 60% or more, and the retention rate of the nap coverage after stretching 40% in any one in-plane direction of the artificial leather is 70% or more. The artificial leather according to claim 1 or 2, wherein the tensile strength in any in-plane direction is 10 N / cm or more. Claims 1 to 3 wherein the thermoplastic resin composition is a composition containing a polyester resin as a main component, and 1 to 500 ppm of 1,2-propanediol is contained as a diol component of the polyester resin. The artificial leather described in either. The artificial leather according to any one of claims 1 to 4, wherein the biomass plastic degree specified in ISO 16620 (2015) is 10% or more and 100% or less. A sheet-like material composed of a thermoplastic resin composition and containing ultrafine fibers having an average single fiber diameter of 1 μm or more and 10 μm or less and a polymer elastic body as constituent elements is cut in half in the thickness direction to form a half-cut surface. Then, at least the half-cut surface of the obtained sheet-like material is ground so that the thickness of the sheet-like material is 70% or less to form a raised sheet, and the raised sheet is 5% or more and 20% in the longitudinal direction thereof. The method for producing artificial leather according to any one of claims 1 to 5, wherein the artificial leather is stretched below.