JP7720140B2 - synthetic leather - Google Patents

Description

The present invention relates to synthetic leather, and in particular to synthetic leather that maintains mechanical strength even when highly loaded with additives that are solid at room temperature.

Natural leather has long been used as an integral part of everyday life, and has been used in a variety of applications as a tough material with moisture absorption, heat resistance, and cold resistance properties due to the leather fabric's properties. However, natural leather is limited in supply and suffers from problems such as embrittlement and discoloration due to swelling, so synthetic leather and artificial leather are used as alternatives.
Synthetic leather and artificial leather are made to resemble natural leather, but are lighter and easier to handle than natural leather. As a result, they are used in a wide range of applications, including vehicle interior materials such as seat covers, furniture such as sofas and chair seats, and clothing such as jackets and coats.
As synthetic leather is used in such a wide range of applications, various functions are required depending on the application.
The desired functions include, for example, antibacterial properties, deodorizing properties, stain resistance, abrasion resistance, conductivity, antistatic properties, lubricity, moisture absorption, and flame retardancy.

As examples of functional synthetic leather, Patent Document 1 discloses synthetic leather with flame retardant properties, and Patent Document 2 discloses synthetic leather with stain-resistant properties.

When attempting to impart functionality to synthetic leather, it is inevitable that it will contain various additives. Additives can be liquid or solid at room temperature. Additives that are solid at room temperature are advantageous because they are less likely to cause deterioration of the synthetic leather over time due to denaturation or volatilization, or unexpected reactions with other components that make up the synthetic leather. However, if additives that are solid at room temperature are heavily loaded into a synthetic resin layer, the mechanical strength of the synthetic resin layer may be impaired, resulting in a synthetic leather that lacks strength.

Patent re-publication No. WO15/166659 JP 2011-231421 A

In light of these problems, the inventors set out to provide synthetic leather that can maintain mechanical strength even when a layer made of synthetic resin is heavily loaded with additives that are solid at room temperature.

The inventors conducted extensive research to solve the above problems and completed the present invention.

The present invention provides the following.
(1) A synthetic leather comprising at least a layer made of synthetic resin and a fiber fabric substrate, wherein the layer made of synthetic resin is composed of three or more layers, laminated in the following order from the surface side: a skin layer, a reinforcing layer, and an adhesive layer; the skin layer, the reinforcing layer, and the adhesive layer are made of polyurethane-based resin or polyvinyl chloride-based resin; the skin layer and the adhesive layer contain additives that are solid at room temperature, and the additives that are solid at room temperature in the skin layer are one or a combination of a conductive agent, an antibacterial agent, and a deodorizing agent, and a pigment; the additives that are solid at room temperature in the adhesive layer are a flame retardant and a pigment; the content of the additives that are solid at room temperature in the skin layer is 15 to 70 mass %, the content of the additives that are solid at room temperature in the adhesive layer is 20 to 70 mass %, and the content of the additives that are solid at room temperature in the reinforcing layer is smaller than the content of the additives that are solid at room temperature in the skin layer and the adhesive layer.
(2) The synthetic leather according to (1), characterized in that the content of the additive that is solid at room temperature in the reinforcing layer is 15% by mass or less.
(3) Synthetic leather according to (1) or (2), characterized in that the thickness of the reinforcing layer accounts for 20% to 80% of the total thickness of the layers made of synthetic resin.

The synthetic leather of the present invention does not lose its mechanical strength even when the layer made of synthetic resin that constitutes the synthetic leather is highly filled with additives that are solid at room temperature.
This makes it possible to provide synthetic leather with a variety of functions.

1 is a cross-sectional view showing an embodiment of the synthetic leather of the present invention.

The synthetic leather of the present invention will be explained using Figure 1. All cross sections in Figure 1 are taken in the thickness direction of the synthetic leather.

The synthetic leather 100 of the present invention comprises at least a layer made of synthetic resin and a fiber fabric substrate 20, and the layer made of synthetic resin is composed of three or more layers, laminated in the following order from the surface side: a skin layer 10, a reinforcing layer 50, and an adhesive layer 40.
In the present invention, the term "layer made of synthetic resin" means "a layer composed of 30% by mass or more of synthetic resin", and is not limited to a layer made of synthetic resin only.
In addition, in the present invention, "additives that are solid at room temperature" means "additives that are solid at room temperature of 20°C ± 15°C (5 to 35°C)" regardless of whether they are organic or inorganic. Examples of solids include powders and granular materials, and their particle size is preferably 100 μm or less. In addition, in the present invention, "additives" is a general term for substances that are added for the function, use, or molding convenience of the final product, and does not include monomers, oligomers, polymers, crosslinking agents, etc. that form the synthetic resin itself.
The synthetic resin constituting the synthetic resin layer of the present invention may be any resin that can be used in synthetic leather, but polyurethane-based resins or polyvinyl chloride-based resins are preferred.

Any polyurethane resin suitable for use in the surface layer of synthetic leather can be used. Specific examples include polyester polyurethane resin, polyether polyurethane resin, polycaprolactone polyurethane resin, polyester/polyether copolymer polyurethane resin, polyamino acid/polyurethane copolymer resin, and non-yellowing polycarbonate polyurethane resin obtained by reacting a polycarbonate diol component with a non-yellowing diisocyanate component and a low-molecular-weight chain extender. Furthermore, polyvinyl chloride resin, synthetic rubber, etc. may be mixed with the polyurethane resin, as long as the physical properties of the synthetic leather are not impaired.

Any polyvinyl chloride resin can be used as long as it can be used for the surface layer of synthetic leather. Specifically, polyvinyl chloride, copolymers of vinyl chloride monomers with other monomers copolymerizable therewith, or blends of these resins can be used.
Examples of other monomers copolymerizable with the vinyl chloride monomer include ethylene, propylene, vinyl acetate, vinylidene chloride, acrylic acid, acrylic acid esters, methacrylic acid, methacrylic acid esters, maleic acid, and acrylonitrile fumarate.

When the synthetic resin layer is made of polyvinyl chloride resin, a plasticizer is blended with the polyvinyl chloride resin to more effectively achieve flexibility similar to that of natural leather. Examples of plasticizers include common phthalate ester plasticizers such as dioctyl phthalate (DOP), diisononyl phthalate (DINP), butyl benzyl phthalate (BBP), diisodecyl phthalate (DIDP), and diundecyl phthalate (DUP), as well as common fatty acid ester plasticizers such as dioctyl adipate (DOA), dioctyl sebacate (DOS), and dioctyl azelaate (DOZ). Examples of suitable plasticizers include polymeric plasticizers such as trimellitic acid trioctyl ester plasticizers and adipic acid polyester plasticizers typified by polypropylene adipate, sebacic acid plasticizers, and phosphate ester plasticizers such as tricresyl phosphate (TCP), trixylenyl phosphate (TXP), tris(isopropylphenyl) phosphate, tributyl phosphate, triethyl phosphate, triphenyl phosphate, and triethylphenyl phosphate.

[Epidermal layer]
The surface layer 10 of the present invention contains an additive that is solid at room temperature. When attempting to impart functionality to the synthetic leather 100, if the surface side contains a functional additive that is solid at room temperature, the properties of the additive that is solid at room temperature can be effectively exhibited.
The additive that is solid at room temperature is preferably contained in the skin layer 10 in a proportion of 15 to 70% by mass. If the proportion of the additive that is solid at room temperature in the skin layer 10 is less than 15% by mass, the function of the additive that is solid at room temperature may not be fully exhibited. On the other hand, if the proportion of the additive that is solid at room temperature in the skin layer 10 is more than 70% by mass, the skin layer 10 becomes hard and brittle, and the mechanical strength of the synthetic leather 100 tends to be unable to be ensured even if the reinforcing layer 50 described below is provided.

There are no limitations on the type of additive that is solid at room temperature, but examples of additives that are conductive include titanium oxide, zinc oxide, carbon black, silver, copper, nickel, tin, tin oxide, indium oxide, and copper-plated fiber.
Examples of additives that have antibacterial properties and are solid at room temperature include those in which metals such as silver, copper, and zinc are supported on various supports, such as silver supported on a glass support and silver-zinc supported on a zeolite support.
Examples of additives that have deodorizing properties and are solid at room temperature include activated carbon, activated carbon fiber, zeolite, bentonite, and silica.
In addition, additives that are solid at room temperature and can impart properties such as stain resistance, abrasion resistance, lubricity, moisture absorption, and flame retardancy may also be used.

The thickness of the skin layer 10 is not particularly limited, but it is preferably formed to a thickness of 10 μm or more and 300 μm or less, and more preferably formed to a thickness of 10 μm or more and 200 μm or less.

[Adhesive layer]
The adhesive layer 40 of the present invention is a layer provided to improve adhesion with the fiber fabric substrate 20 described below. Because the adhesive layer 40 is a layer that comes into contact with the fiber fabric substrate 20, it contains various additives that are solid at room temperature to compensate for performance that the fiber fabric substrate 20 does not have or that the fiber fabric substrate 20 lacks.
Furthermore, in the present invention, as described above, various additives that are solid at room temperature are contained in the surface layer 10 to give it functionality. However, since there is a limit to the amount of additives that are solid at room temperature that can be contained in the surface layer 10, there are cases in which additives that are solid at room temperature that could not be contained in the skin layer 10 are contained in the adhesive layer 40.
This will be specifically explained using the case of imparting electrical conductivity and flame retardancy to synthetic leather 100. When attempting to impart electrical conductivity and flame retardancy to synthetic leather, it is more effective to include an additive that is solid at room temperature and has electrical conductivity in a layer closer to the surface of the synthetic leather, and therefore it is included in the surface layer 10. As the proportion of the additive that is solid at room temperature and has electrical conductivity contained in the surface layer 10 increases, it becomes more difficult to add other additives that are solid at room temperature to the surface layer 10, and therefore it is considered to add the additive that is solid at room temperature and has flame retardancy to another layer.
Here, if the amount of flame-retardant additive that is solid at room temperature added is large, and the layer is adjacent to a surface layer 10 that is highly filled with conductive additives that are solid at room temperature, the mechanical strength of the synthetic leather 100 cannot be ensured. Therefore, by incorporating a flame-retardant additive that is solid at room temperature in the adhesive layer 40 that is not adjacent to the surface layer 10, synthetic leather that is both conductive and flame-retardant can be obtained.

The content of the additive that is solid at room temperature in the adhesive layer 40 is preferably 20 to 70% by mass. If the content of the additive that is solid at room temperature in the adhesive layer 40 is less than 20% by mass, the function of the additive that is solid at room temperature may not be fully exerted. On the other hand, if the content of the additive that is solid at room temperature in the adhesive layer 40 exceeds 70% by mass, the adhesive layer 40 becomes hard and brittle, making it difficult to maintain the mechanical strength of the synthetic leather 100 even if the reinforcing layer 50 described below is provided, and is likely to cause poor adhesion to the fiber fabric substrate 20.

The additive that is solid at room temperature and added to the adhesive layer 40 is preferably one that can impart flame retardancy. This is because if the adhesive layer has flame retardancy, the synthetic leather 100 as a whole will have flame retardancy even if the front side of the synthetic leather 100 does not have a flame retardant effect.
Examples of flame-retardant additives that are solid at room temperature include hydrated metals such as aluminum hydroxide and magnesium hydroxide, phosphorus-based additives such as red phosphorus and phosphates, nitrogen-based additives such as ammonium carbonate, zinc borate, and molybdenum compounds.

The thickness of the adhesive layer 40 is not particularly limited, but it is preferably formed to a thickness of 10 μm or more and 300 μm or less, and more preferably formed to a thickness of 10 μm or more and 200 μm or less.

[Reinforcing layer]
The reinforcing layer 50 of the present invention is a layer provided to ensure the strength of the layer made of synthetic resin of the synthetic leather, and the content of additives that are solid at room temperature in the reinforcing layer 50 is smaller than the content of additives that are solid at room temperature in the surface layer 10 and the adhesive layer 40.
By interposing a reinforcing layer 50 between the surface layer 10 and the adhesive layer 40, which contains a smaller proportion of additives that are solid at room temperature than the surface layer 10 and the adhesive layer 40, it is possible to ensure the mechanical strength required of synthetic leather.
The reinforcing layer 50 preferably contains a synthetic resin as a main component, but may contain an additive that is solid at room temperature as needed. In this case, the content of the additive that is solid at room temperature in the reinforcing layer 50 is preferably 15 mass % or less.
The reinforcing layer 50 may be a foamed layer (foamed layer) or a non-foamed layer (non-foamed layer).
The means for foaming the reinforcing layer 50 include physical foaming by mechanical stirring, chemical foaming by adding a foaming agent, and pseudo-foaming by adding hollow particles.

The reinforcing layer 50 may be a single layer or a multi-layer structure consisting of two or more layers. In the case of a multi-layer structure, it is acceptable as long as each layer contains a smaller proportion of additives that are solid at room temperature than the skin layer 10 and adhesive layer 40.

The thickness of the reinforcing layer 50 is not particularly limited, but it is preferably formed to a thickness of 10 μm or more and 300 μm or less, and more preferably formed to a thickness of 10 μm or more and 200 μm or less.

In the synthetic resin layers comprising the surface layer 10, adhesive layer 40, and reinforcing layer 50, the thickness of the reinforcing layer 50 is preferably 20% to 80% of the total thickness of the synthetic resin layers. If the thickness of the reinforcing layer 50 is less than 20%, it tends to be difficult to ensure the mechanical strength required of synthetic leather. Furthermore, if the thickness of the reinforcing layer 50 exceeds 80%, the thicknesses of the surface layer 10 and adhesive layer 40 will be relatively small, and even if the surface layer 10 and adhesive layer 40 are highly filled with additives that are solid at room temperature, the content of the additives that are solid at room temperature relative to the total synthetic leather 100 will be small, making it difficult to impart the desired functionality to the synthetic leather 100.

The skin layer 10, adhesive layer 40, and reinforcing layer 50 may contain various additives that are liquid at room temperature, as long as they do not impair the physical properties of each layer.

[Fiber fabric substrate]
The fiber fabric substrate 20 is not particularly limited and may be any fabric material using fibers, such as knitted fabric, woven fabric, or nonwoven fabric. The fibers forming the fiber fabric substrate 20 are not particularly limited and may include synthetic fibers, natural fibers, and the like. Examples of synthetic fiber materials include, but are not limited to, polyester, polyamide, acrylic, and nylon. Examples of natural fiber materials include, but are not limited to, cotton, linen, and rayon.
The fibers constituting the fiber fabric substrate 20 may be flame-retardant treated fibers, conductive treated fibers, or partially metallic fibers.
The thickness of the fiber fabric substrate 20 is not particularly limited, but considering the mechanical strength, texture, etc. of the synthetic leather 100, the thickness is preferably 100 μm or more and 2000 μm or less, and more preferably 300 μm or more and 1000 μm or less. The basis weight of the fiber fabric substrate 20 is also not particularly limited, but similarly to the thickness, considering the mechanical strength, texture, etc. of the synthetic leather, the basis weight is preferably 30 g/ ^m2 or more and 800 g/m2 or ^less , and more preferably 50 g/ ^m2 or more and 500 g/ ^m2 or less.

[Surface treatment layer]
The synthetic leather 100 of the present invention may have a surface treatment layer 30 provided on the skin layer 10 .
The surface treatment layer 30 is provided for the purposes of glossing/mattifying the synthetic leather 100, imparting abrasion resistance, providing a good feel, and imparting stain resistance. The surface treatment layer 30 can be provided by coating the surface of the skin layer 10 with a coating liquid prepared by dispersing polyurethane resin, silicone, and various additives in an organic solvent or water.

A primer layer may be provided between the surface treatment layer 30 and the skin layer 10 to improve adhesion between them. The primer layer is made of resin, and pigments, antioxidants, UV absorbers, catalysts, and various additives may be added as needed.

Next, a method for manufacturing the synthetic leather 100 of the present invention will be described based on the first embodiment. Note that the manufacturing method described below is an example and is not limited to the following manufacturing method.

First, a skin layer-forming composition for forming the skin layer 10 is applied to a release carrier such as release paper, and then reacted and solidified to form the skin layer 10. Skin layer-forming composition A can be applied using a knife coater, comma doctor, roll coater, reverse roll coater, rotary screen coater, gravure coater, or other appropriate means. The surface of the release carrier on which the skin layer-forming composition is applied may be smooth or may have a grained pattern. When a release carrier with a grained pattern or the like is used, the grained pattern of the release carrier is transferred to the surface of the skin layer 10 of the synthetic leather 100, resulting in a synthetic leather 100 with a grained pattern design.

Next, a composition for forming a reinforcing layer is applied onto the surface skin layer 10. The same method as for applying the composition for forming a surface skin layer can be used for applying the composition for forming a reinforcing layer. The applied composition for forming a reinforcing layer is dried to form the reinforcing layer 50.
Next, the adhesive layer-forming composition is applied onto the reinforcing layer 50. The adhesive layer-forming composition can be applied using the same method as for the skin layer-forming composition and the reinforcing layer-forming composition. After the applied adhesive layer-forming composition is dried until it becomes semi-gel-like, the fiber fabric substrate 20 is laminated thereon.
Thereafter, the releasable carrier is peeled off, and if necessary, a surface treatment layer 30 is provided on the surface of the skin layer 10, thereby obtaining the synthetic leather 100 shown in Fig. 1. The surface treatment layer 30 can be formed by a method such as a gravure coater, a reverse roll coater, or a spray coater.
The synthetic leather 100 obtained as described above may be embossed to form a pattern.

The synthetic leather 100 of the present invention has been described above. The synthetic leather 100 of the present invention can be used for a variety of purposes.

The present invention will be described in detail below based on examples.
The components of the synthetic leathers used in Examples 1 to 7 and Comparative Examples 1 and 2 are as follows:

<Resin composition for epidermis layer>
Main component: Polycarbonate-based polyurethane resin solution (DIC Corporation's "Crisbon NY335FT")
Solvent 1: DMF
・Solvent 2: Ethyl acetate ・Conductive agent: Zinc oxide (Panatetra, manufactured by Amtec Co., Ltd.) ・Antibacterial agent: Glass-silver antibacterial agent (Ion Pure NDC-K, manufactured by Ishizuka Glass Co., Ltd.)
Deodorizer: Zirconium phosphate (Kesmon NS-10, manufactured by Toagosei Co., Ltd.)
Pigment: Black pigment (DIC Corporation, Dilac L-1770)

<Resin composition for adhesive layer>
Main component: Polycarbonate-based polyurethane resin solution (DIC Corporation's "Crisbon TA205FT")
Crosslinking agent: Isocyanate compound (DIC Corporation's "Burnoc DN950")
Solvent 1: DMF
Solvent 2: MEK
Catalyst: "Crisbon Accel T81-E" manufactured by DIC Corporation
Pigment: Black pigment (DIC Corporation, Dilac L-1770)
Flame retardant: Phosphorus-based flame retardant (Pecoflame HFC manufactured by Clariant Japan)

<Reinforcing layer resin composition>
- Main component: Polycarbonate-based polyurethane resin (TA215FT manufactured by DIC Corporation)
Crosslinking agent: Isocyanate compound (DIC Corporation's "Burnoc DN950")
Solvent 1: DMF
Solvent 2: MEK
Catalyst: "Crisbon Accel T81-E" manufactured by DIC Corporation
Conductive agent: Zinc oxide (Panatetra, manufactured by Amtec Co., Ltd.) Pigment: Black pigment (Dialac L-1770, manufactured by DIC Corporation)

<Fiber fabric substrate>
Polyester fabric knitted on a circular knitting machine from 150 denier polyester yarn.

Example 1
A resin composition for a surface layer, consisting of a base material: 100 parts by mass of a polycarbonate-based polyurethane resin solution (resin solid content: 20% by mass), 30 parts by mass of solvent 1, 30 parts by mass of solvent 2, 13 parts by mass of a conductive agent, and 20 parts by mass of a pigment (resin solid content: 10% by mass, pigment equivalent (equivalent to an additive that is solid at room temperature): 8% by mass), was applied to release paper using a comma coater, and the temperature was gradually increased from 80°C to 120°C. After reaching 120°C, the composition was dried for 5 minutes to obtain a surface layer having a thickness of 30 μm.
Next, a resin composition for the reinforcing layer, consisting of 100 parts by weight of a polycarbonate-based polyurethane resin solution (resin solid content 50% by weight), 10 parts by weight of a crosslinking agent (resin solid content 75% by weight), 30 parts by weight of a solvent 1, 20 parts by weight of a solvent 2, 2 parts by weight of a catalyst (resin solid content 15% by weight), 3 parts by weight of a conductive agent, and 20 parts by weight of a pigment (resin solid content 10% by weight, pigment equivalent (equivalent to an additive that is solid at room temperature) 8% by weight), was applied onto the surface layer using a comma coater and dried at 120°C to obtain a reinforcing layer with a thickness of 50 μm.
Next, a resin composition for the adhesive layer consisting of 100 parts by weight of main component: polycarbonate-based polyurethane resin solution (70% by weight of resin solids), 12 parts by weight of crosslinker (75% by weight of resin solids), 30 parts by weight of solvent 1, 30 parts by weight of solvent 2, 2 parts by weight of catalyst (15% by weight of resin solids), 20 parts by weight of pigment (10% by weight of resin solids, 8% by weight of pigment equivalent (equivalent to additives that are solid at room temperature)), and 52 parts by weight of flame retardant was applied to the reinforcing layer using a comma coater and dried at 70°C to obtain an adhesive layer approximately 50 μm thick.
Next, when the adhesive layer had developed adhesiveness, the substrate 1 was attached.
The resulting product was then wound into a roll and aged at 50°C for 48 hours. The release paper was then peeled off to obtain a synthetic leather having the surface layer, adhesive layer, and fiber fabric substrate laminated in this order.
According to the above formulation, the total content of the conductive agent and pigment, which are additives that are solid at room temperature, in the surface layer is 40% by mass, the total content of the conductive agent and pigment, which are additives that are solid at room temperature, in the reinforcing layer is 7.1% by mass, and the total content of the flame retardant and pigment, which are additives that are solid at room temperature, in the adhesive layer is 40% by mass.

Example 2
Synthetic leather was obtained in the same manner as in Example 1, except that the amount of conductive agent added to the surface layer was changed so that the content of the additive that was solid at room temperature in the surface layer was 20 mass %.

Example 3
Synthetic leather was obtained in the same manner as in Example 1, except that the amount of conductive agent added to the surface layer was changed so that the content of the additive that was solid at room temperature in the surface layer was 70 mass %.

Example 4
A synthetic leather was obtained in the same manner as in Example 1, except that the amount of conductive agent added to the reinforcing layer was changed so that the content of the additive that was solid at room temperature in the reinforcing layer was 15 mass %.

Example 5
A synthetic leather was obtained in the same manner as in Example 1, except that the amount of conductive agent added to the reinforcing layer was changed so that the content of the additive that was solid at room temperature in the reinforcing layer was 20 mass %.

Example 6
A synthetic leather was obtained in the same manner as in Example 1, except that the 12 parts by mass of conductive agent in the surface layer was changed to 12 parts by mass of antibacterial agent, and the content of additives (total of antibacterial agent and pigment) that are solid at room temperature in the surface layer was changed to 40% by mass.

Example 7
A synthetic leather was obtained in the same manner as in Example 1, except that the 12 parts by mass of conductive agent in the surface layer was changed to 12 parts by mass of deodorant, and the content of additives (total of deodorant and pigment) that are solid at room temperature in the surface layer was 40% by mass.

(Comparative Example 1)
A synthetic leather was obtained in the same manner as in Example 1, except that no reinforcing layer was provided.

(Comparative Example 2)
A synthetic leather was obtained in the same manner as in Example 1, except that the amount of the conductive agent was increased so that the content of the additive that is solid at room temperature in the reinforcing layer was 50 mass %.

The synthetic leathers obtained in each example and comparative example were evaluated as follows:

<Bending resistance>
The synthetic leathers obtained in Examples 1 to 7 and Comparative Examples 1 and 2 were evaluated for flex resistance in accordance with JIS K 6542, a test method for testing the cold resistance of leather. Test pieces cut to a length of 70 mm and a width of 45 mm were placed in a flexometer equipped with a low-temperature bath adjusted to -20°C, and the presence or absence of cracks was checked every 5,000 times, and the number of times required for the crack to occur was recorded.
The results are shown in Table 1.
Here, if the flex resistance is 5,000 times or more, the mechanical strength required for synthetic leather is ensured, and if it is 10,000 times or more, the synthetic leather can be said to have excellent flex resistance.On the other hand, if the flex resistance is less than 5,000 times, the mechanical strength required for synthetic leather cannot be ensured .
In the table, "2.0 to 2.5" indicates that no cracks were observed after 20,000 observations, but that cracks were observed after 25,000 observations, and the same applies to other notations. Also, "<0.5" indicates that cracks were observed after 5,000 observations.

<Flame retardancy>
The synthetic leathers obtained in Examples 1 to 7 and Comparative Examples 1 and 2 were evaluated for flame retardancy.
Each synthetic leather was cut into a test piece measuring 10 cm wide x 30 cm long. Each test piece was hung vertically from above, and a burner flame was applied to the center of the lower end of the test piece for 60 seconds. The flame was then removed from the test piece by moving the burner. After the removal, the time the test piece continued to burn with the flame (hereinafter referred to as the "flame time") and the length of the burned area from the lower end (hereinafter referred to as the "burning length") were measured.
Flame times of 15 seconds or less and burn lengths of less than 15.2 cm (6 inches) are evaluated as "○", while flame times of more than 15 seconds or burn lengths of 15.2 cm (6 inches) or more are evaluated as "×". All test pieces were evaluated as "○".

<Conductivity>
The synthetic leathers obtained in Examples 1 to 5 and Comparative Examples 1 and 2 were evaluated for electrical conductivity.
The surface resistance value of the skin layer side was measured in accordance with the method described in IEC Standard 61340-2-3 (2000) under conditions of a temperature of 23±2° C. and a humidity of 60±5% RH.
The measurement device used was a product of Prostat Co., Ltd., trade name "PRS-801," and the measurement probe used was a 5-pound electrode (PRS-801-W), with an inter-electrode distance of 60 mm and an applied voltage of 100V.
A surface resistivity of less than 1.0×10 ¹¹ Ω is considered to be conductive.

<Antibacterial>
The synthetic leather obtained in Example 6 was evaluated for antibacterial properties.
An antibacterial test was conducted in accordance with JIS Z2801 under conditions of water resistance category 1 and light resistance category 1, and the antibacterial activity value against Staphylococcus aureus was 3.2.
An antibacterial activity value of 2.0 or more is considered to have antibacterial properties.

<Deodorizing properties>
The synthetic leather obtained in Example 7 was evaluated for deodorizing properties. The test method was as follows.
Test container: 5L Smart Bag PA
・Gas used: Ammonia ・Gas volume in the container: 3L
Initial ammonia concentration: 100 ppm
Gas measurement method: Gas detector tube Sample size: 100 ^cm²
Sampling: Measure the ammonia concentration after 120 minutes Blank test: Measure the ammonia concentration after 120 minutes without adding a sample In the above tests, the ammonia reduction rate (%) was evaluated according to the following criteria. The reduction rate was calculated using the following formula:
Reduction rate (%) = (remaining gas concentration in blank test - gas concentration in each test sample) / blank test x 100
The reduction rate was 85%.
If the reduction rate is 70% or more, it is considered to have deodorizing properties.

As can be seen from Table 1, in Examples 1 to 7, the surface layer and adhesive layer are highly filled with additives that are solid at room temperature, but because they are provided with a reinforcing layer, they have bending resistance and can ensure the mechanical strength required for synthetic leather.
It is also apparent that Examples 1 to 5 exhibit electrical conductivity, Example 6 exhibits antibacterial properties, and Example 7 exhibits deodorizing properties.
On the other hand, it can be seen that in Comparative Example 1, which does not have a reinforcing layer, and Comparative Example 2, in which the content of additives that are solid at room temperature in the reinforcing layer is higher than in the skin layer and adhesive layer, the mechanical strength required for synthetic leather cannot be guaranteed.

10: Surface layer 20: Fibrous base material layer 30: Surface treatment layer 40: Adhesive layer 50: Reinforcement layer 100: Synthetic leather

Claims (3)

A synthetic leather having at least a layer made of synthetic resin and a fiber fabric substrate, wherein the layer made of synthetic resin is composed of three or more layers, laminated in the order of a surface layer, a reinforcing layer, and an adhesive layer from the surface side;
The surface layer, reinforcing layer, and adhesive layer are made of polyurethane resin or polyvinyl chloride resin.
the surface layer and the adhesive layer contain an additive that is solid at room temperature;
the additive in the surface layer that is solid at room temperature comprises one or a combination of a conductive agent, an antibacterial agent, and a deodorizing agent, and a pigment;
The additives in the adhesive layer that are solid at room temperature are flame retardants and pigments.
The content of the additive in the skin layer that is solid at room temperature is 15 to 70 mass %;
The content of the additive that is solid at room temperature in the adhesive layer is 20 to 70 mass %;
1. A synthetic leather characterized in that the content of an additive that is solid at room temperature in the reinforcing layer is smaller than the content of an additive that is solid at room temperature in the surface layer and the adhesive layer. The synthetic leather described in claim 1, characterized in that the content of additives that are solid at room temperature in the reinforcing layer is 15% by mass or less. Synthetic leather according to claim 1 or 2, characterized in that the thickness of the reinforcing layer is 20% to 80% of the total thickness of the synthetic resin layer.