Patent Application
20250066996
The present invention relates to a synthetic leather.
Among synthetic leathers, the synthetic leather with a film containing a vinyl chloride-based resin as a main component has flexibility such as high bendability and softness, and strength. As the strength, for example, abrasion resistance against a friction phenomenon which is repeatedly received is exemplified. A synthetic leather is used in various fields, application examples thereof include vehicle interior materials such as a vehicle seat and a door lining, interior materials such as furniture and a chair, and fashion materials such as a bag and shoes. Since these applications are subjected to severe use conditions, high durability is desired. Among these, in the case of the synthetic leather used in a part at which there are many opportunities to direct or indirect contact with the human body, oil resistance to sebum secreted from the human body or to an oily component contained in cosmetics is desired. In particular, durability against higher fatty acids such as oleic acid, which is a main component of sebum, is strongly desired.
For example, PTL 1 describes that a surface treatment layer is formed by applying a surface treatment agent obtained by crosslinking a mixture of polycarbonate urethane and ester urethane with a crosslinking agent containing a carbodiimide group to a surface side of a film containing a vinyl chloride resin as a main component. In PTL 1, it is described that, by forming the surface treatment layer, in addition to high flexibility and good strength, abrasion resistance against repeated friction phenomena received and chemical resistance (oleic acid resistance) against contact with a human body can be improved.
Although the synthetic resin leather in PTL 1 has good chemical resistance (oleic acid resistance), higher oil resistance is desired.
On the other hand, from the viewpoint of cost reduction, ensuring a certain level of quality, and the like, a synthetic leather is desired to have a structure that is easy to produce, that is, processability (or manufacturability).
The invention has been made in view of such circumstances, and an object thereof is to provide a synthetic leather that is excellent in oil resistance and processability.
A synthetic leather according to an embodiment of the invention includes a fibrous substrate, a foam layer containing a vinyl chloride-based resin and a plasticizer, and a non-foam layer containing a vinyl chloride-based resin and a plasticizer, in this order. In each of the foam layer and the non-foam layer, a content of the plasticizer is from 60 to 100 parts by mass with respect to 100 parts by mass of the vinyl chloride-based resin, the plasticizer contains a phthalate ester-based plasticizer and a polyester-based plasticizer, and a mass ratio of the phthalate ester-based plasticizer to the polyester-based plasticizer is from 73:27 to 87:13.
According to an embodiment of the invention, a synthetic leather having excellent oil resistance and processability can be provided.
The synthetic leather according to the present embodiment includes a fibrous substrate, a foam layer containing a vinyl chloride-based resin and a plasticizer, and a non-foam layer containing a vinyl chloride-based resin and a plasticizer. The foam layer and the non-foam layer contain from 60 to 100 parts by mass of the plasticizer with respect to 100 parts by mass of the vinyl chloride-based resin. The plasticizer used in the foam layer and the non-foam layer is a phthalate ester-based plasticizer and a polyester-based plasticizer, and a mass ratio of the phthalate ester-based plasticizer to the polyester-based plasticizer is from 73:27 to 87:13. By adopting such a configuration, it is possible to obtain a synthetic leather having good processability in a casting method and a soft texture while oil resistance is good.
In the examples of
The fibrous substrate is not particularly limited, and for example, a fiber fabric such as a woven fabric, a knitted fabric, and a nonwoven fabric, a natural leather (including a split leather), and the like can be used. As the fiber fabric, a fiber fabric applied or impregnated with a conventionally known solvent-based or non-solvent-based polymer compound and subjected to dry coagulation or wet coagulation may be used. The non-solvent-based system as used herein includes a water-based system. Further, examples of the polymer compound include a polyurethane resin and a vinyl chloride-based resin. Among these, the knitted fabric is preferable and a circular knitted fabric is more preferable, as the fibrous substrate, from the viewpoint of leather-like properties (specifically, grain-texture, thickness, and texture like those of natural leather), strength, elongation properties, and the like.
The type of the fiber in the fiber fabric is not particularly limited, and examples thereof include conventionally known fibers such as a natural fiber, a recycled fiber, a semi-synthetic fiber, and a synthetic fiber, and two or more types thereof may be combined. Among these, from the viewpoint of strength and processability, a synthetic fiber is preferable and a polyester fiber is more preferable, as the fiber.
The shape of the fiber is not particularly limited, and the fiber may be either a long fiber or a short fiber. The form of yarn forming the fibrous substrate may be a short fiber yarn such as a spun yarn, a long fiber yarn such as a multifilament yarn or a monofilament yarn, or a long and short composite spun yarn in which a long fiber and a short fiber are combined. From the viewpoint that softness can be imparted to the resulting fibrous substrate, as the yarn, a short fiber subjected to a crimping process in advance may be used, or a process such as a false twisting process or a fluid disturbing treatment may be performed in a state of the yarn.
The fibrous substrate may be colored with a dye or a pigment.
The synthetic leather according to the embodiment includes a foam layer and a non-foam layer, as a resin layer containing a vinyl chloride-based resin and a plasticizer. The foam layer is a resin layer having a bubble, and may be a porous layer. Unlike the foam layer, the non-foam layer is a resin layer having no bubbles. The non-foam layer is a resin layer laminated on a surface of the foam layer, and is also referred to as a skin layer.
The vinyl chloride-based resin forming the non-foam layer is a polymer formed from vinyl chloride and/or vinylidene chloride, as a monomer component. The vinyl chloride-based resin is not particularly limited, and a conventionally known vinyl chloride-based resin can be used. Examples thereof include a vinyl chloride resin and/or a vinylidene chloride resin. Examples of the vinyl chloride resin include polyvinyl chloride, which is a homopolymer of vinyl chloride, and a copolymer of vinyl chloride and another monomer. Examples of the vinylidene chloride resin include polyvinylidene chloride, which is a homopolymer of vinylidene chloride, and a copolymer of vinylidene chloride and another monomer. These can be used alone or in combination of two or more thereof. Here, examples of the other monomer to be copolymerized with vinyl chloride or vinylidene chloride include vinyl acetate, ethylene, propylene, styrene, acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, maleic acid, maleic acid ester, and higher vinyl ether, and vinyl chloride and vinylidene chloride may be copolymerized.
The resin component forming the non-foam layer preferably contains a vinyl chloride-based resin as a main component. Specifically, more than 50% by mass of the resin component is preferably a vinyl chloride-based resin, more preferably 80% by mass or more of the resin component is a vinyl chloride-based resin, and 100% by mass of the resin component may be a vinyl chloride-based resin. In the specification, the resin component refers to a polymer component excluding an additive such as a plasticizer and a heat stabilizer, among components forming the resin layer.
The non-foam layer contains a phthalate ester-based plasticizer and a polyester-based plasticizer, as a plasticizer. By using the phthalate ester-based plasticizer and the polyester-based plasticizer in combination, the viscosity of the resin composition liquid for the non-foam layer can be suppressed to be low. Therefore, generation of bubbles and a processing streak can be suppressed, and a uniform film can be formed. Therefore, processability, particularly processability in a casting method, is improved. Here, the processing streak refers to a streak-like defect generated along the application direction when the resin composition liquid is applied. The polyester-based plasticizer has a higher molecular weight than other plasticizers. Therefore, by using the polyester-based plasticizer, the diffusion rate of the plasticizer is reduced, and the plasticizer is less likely to migrate from the inside of the non-foam layer to the outside of the non-foam layer. Therefore, oil resistance of the resulting synthetic leather can be improved.
The phthalate ester-based plasticizer refers to a phthalate ester that acts as a plasticizer for the vinyl chloride-based resin. Examples of phthalate ester-based plasticizer include dibutyl phthalate (DBP), dioctyl phthalate (DOP), dinonyl phthalate (DNP), diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), ditridecyl phthalate (DTDP), diundecyl phthalate (DUP), benzyl butyl phthalate (BBP), nonyl undecyl phthalate (NUP), and a dialkyl phthalate (C9 to C11). These can be used alone or in combination of two or more thereof. Since these are esters of phthalic acid and a monohydric alcohol, a phthalic acid-based polyester as a polyester-based plasticizer described later is not included in the phthalate ester-based plasticizer.
In one embodiment, the phthalate ester plasticizer is preferably a dialkyl phthalate, which is an ester of phthalic acid and at least one monohydric alcohol selected from the group consisting of alcohols having from 4 to 20 carbon atoms. Among these, a dialkyl phthalate (C9 to C11) is preferable from the viewpoint of bleeding resistance, cold resistance, and heat resistance. Here, the dialkyl phthalate (C9 to C11) is an ester of phthalic acid and a mixture of alcohols having 9 to 11 carbon atoms.
The polyester-based plasticizer refers to a polyester that acts as a plasticizer for the vinyl chloride-based resin. Examples of the polyester-based plasticizer include those obtained by polycondensation of a dicarboxylic acid and a dihydric alcohol, and examples thereof include an adipic acid-based polyester, a sebacic acid-based polyester, and a phthalic acid-based polyester. These can be used alone or in combination of two or more thereof. Examples of the dihydric alcohol include ethylene glycol, propylene glycol, butanediol (for example, 1,3-butanediol and 1,4-butanediol), and hexanediol (for example, 1,6-hexanediol). These can be used alone or in combination of two or more thereof. The polyester-based plasticizer is preferably an adipic acid-based polyester from the viewpoint of versatility.
The number average molecular weight (Mn) of the polyester-based plasticizer is not particularly limited, and is preferably from 500 to 2500, and more preferably from 1200 to 2000. When the number average molecular weight is 2500 or less, the viscosity of the resin composition liquid for the non-foam layer can be suppressed to be low, and processability, particularly processability in a casting method, can be further improved. When the number average molecular weight is 500 or more, good oil resistance is obtained. Here, the number average molecular weight of the polyester-based plasticizer is calculated as a value in terms of a polystyrene equivalent measured by a gel permeation chromatography (GPC) method.
The viscosity of the polyester-based plasticizer is not particularly limited, and is preferably from 150 to 5000 mPa's, and more preferably from 2000 to 5000 mPa·s. When the viscosity is 150 mPa's or more, the resulting synthetic leather has good oil resistance. When the viscosity is 5000 mPas or less, the viscosity of the resin composition liquid for the non-foam layer can be suppressed to be low, and processability, particularly, processability in a casting method, can be further improved. Here, the viscosity of the polyester-based plasticizer is the viscosity measured with Brookfield type viscometer at 25° C., and more specifically, the viscosity is measured with a BII type viscometer (BHII type, manufactured by Toki Sangyo Co., Ltd., rotor No. 3) at 10 rpm and a liquid temperature of 25° C.
In the non-foam layer, the mass ratio (a blending ratio as a solid content) of the phthalate ester-based plasticizer to the polyester-based plasticizer is (an amount of phthalate ester-based plasticizer):(an amount of polyester-based plasticizer)=from 73:27 to 87:13, and preferably from 77:23 to 83:17. When the blending ratio of the phthalic acid ester-based plasticizer is 73% by mass or more (that is, the blending ratio of the polyester-based plasticizer is 27% by mass or less), the viscosity of the resin composition liquid for the non-foam layer can be suppressed to be low, and processability, particularly, processability by a casting method is improved. When the blending ratio of the phthalate ester-based plasticizer is 87% by mass or less (that is, the blending ratio of the polyester-based plasticizer is 13% by mass or more), good oil resistance is obtained.
In the specification, the mass ratio of the phthalate ester-based plasticizer to the polyester-based plasticizer is an integer ratio obtained by rounding off to the nearest whole number when the ratio of each plasticizer has a fraction after the decimal point in the case in which the total of both plasticizers is 100.
In the specification, the solid content refers to a component other than a volatile substance such as an organic solvent or water, and is also referred to as an evaporation residue or a non-volatile content. Therefore, a liquid that does not evaporate at a normal drying temperature, such as a plasticizer, is also included in the solid content.
The content of the plasticizer (the total content of the phthalate ester-based plasticizer and the polyester-based plasticizer) in the non-foam layer is from 60 to 100 parts by mass, and preferably from 65 to 85 parts by mass, with respect to 100 parts by mass of the vinyl chloride-based resin. When the amount of the plasticizer is 60 parts by mass or more, a soft texture is obtained. In addition, the viscosity of the resin composition liquid for the non-foam layer can be suppressed to be low, and processability, particularly, processability by a casting method is improved. When the amount of the plasticizer is 100 parts by mass or less, strength can be improved. Further, since the bleeding of the plasticizer can be suppressed, the design property can be improved.
In the non-foam layer, conventionally known additives can be blended, if necessary, within a range that does not impair the physical properties thereof. Examples of such additives include a plasticizer other than the phthalate ester-based plasticizer and polyester-based plasticizer, a thermoplastic resin and thermosetting resin other than the vinyl chloride-based resin, a heat stabilizer, a filler, a pigment, an amine resistant agent, a flame retardant, a conductivity-imparting agent, an antistatic agent, an ultraviolet absorber, a light stabilizer, an antioxidant, a pigment dispersant, a crosslinking agent, and a thickening agent, and these can be used alone or in combination of two or more thereof.
Examples of the heat stabilizer include metal soaps such as calcium stearate, magnesium stearate, aluminum stearate, barium stearate, zinc stearate, calcium laurate, barium laurate, and zinc laurate; metal salts such as a sodium salt, a zinc salt, and a barium salt of phenol and/or naphthol; organotin compounds such as dibutyltin dilaurate and dibutyltin dimaleate; and phosphites such as triphenyl phosphite, tricresyl phosphite, and triisooctyl phosphite. These can be used alone or in combination of two or more thereof. In one embodiment, a calcium salt of an organic acid and/or a zinc salt of an organic acid may be used as the thermal stabilizer. The content of the thermal stabilizer is not particularly limited, and may be, for example, from 0.1 to 10 parts by mass or from 0.5 to 5 parts by mass, with respect to 100 parts by mass of the vinyl chloride-based resin.
Examples of the amine resistant agent include perchlorates such as sodium perchlorate and potassium perchlorate. These can be used alone or in combination of two or more thereof. The content of the amine resistant agent is not particularly limited, and may be, for example, from 0.05 to 5 parts by mass or from 0.1 to 2 parts by mass, with respect to 100 parts by mass of the vinyl chloride-based resin.
The thickness of the non-foam layer is not particularly limited, but is preferably from 100 to 300 μm, and more preferably from 130 to 250 μm. When the thickness of the non-foam layer is 100 μm or more, good strength is obtained. When the thickness of the non-foam layer is 300 μm or less, the film thickness of the non-foam layer of the resulting synthetic leather can be made uniformly.
The vinyl chloride-based resin forming the foam layer is a polymer formed from vinyl chloride and/or vinylidene chloride, as a monomer component. The vinyl chloride-based resin is not particularly limited, and the same vinyl chloride-based resin as that of the non-foam layer described above can be used, and thus the description thereof is be omitted. The vinyl chloride-based resin contained in the foam layer and the vinyl chloride-based resin contained in the non-foam layer may be the same or different.
The resin component forming the foam layer preferably contains a vinyl chloride-based resin as a main component. Specifically, more than 50% by mass of the resin component is preferably a vinyl chloride-based resin, more preferably 80% by mass or more of the resin component is a vinyl chloride-based resin, and 100% by mass of the resin component may be a vinyl chloride-based resin.
The foam layer contains a phthalate ester-based plasticizer and a polyester-based plasticizer as a plasticizer. By using the phthalate ester-based plasticizer and the polyester-based plasticizer in combination, the viscosity of the resin composition liquid for the foam layer can be suppressed to be low. Therefore, generation of bubbles and processing streaks can be suppressed, and a uniform film can be formed. Therefore, processability, particularly processability in a casting method, is improved. The polyester-based plasticizer has a higher molecular weight than other plasticizers. Therefore, by using the polyester-based plasticizer, the diffusion rate of the plasticizer into other resin layers is reduced, and the plasticizer is less likely to migrate from the inside of the foam layer to the outside of the foam layer. Thus, good oil resistance is obtained.
The phthalic acid ester-based plasticizer and the polyester-based plasticizer in the foam layer are not particularly limited, and the same phthalic acid ester-based plasticizer and polyester-based plasticizer as those of the non-foam layer described above can be used. Therefore, similar to the non-foam layer, a dialkyl phthalate (C9 to C11) is preferable as a phthalate ester-based plasticizer, an adipic acid-based polyester is preferable as a polyester-based plasticizer, the number average molecular weight of the polyester-based plasticizer is preferably from 500 to 2500 (more preferably from 1200 to 2000), and the viscosity of the polyester-based plasticizer is preferably from 150 to 5000 mPa's (more preferably from 2000 to 5000 mPas). The phthalate ester-based plasticizer and the polyester-based plasticizer contained in the foam layer may be the same as or different from the phthalate ester-based plasticizer and the polyester-based plasticizer contained in the non-foam layer.
In the foam layer, the mass ratio (a blending ratio as a solid content) of the phthalate ester-based plasticizer to the polyester-based plasticizer is (an amount of phthalate ester-based plasticizer):(an amount of polyester-based plasticizer)=from 73:27 to 87:13, and preferably from 77:23 to 83:17. When the blending ratio of the phthalic acid ester-based plasticizer is 73% by mass or more (that is, the blending ratio of the polyester-based plasticizer is 27% by mass or less), the viscosity of the resin composition liquid for the foam layer can be suppressed to be low, and processability, particularly, processability by a casting method is improved. When the blending ratio of the phthalate ester-based plasticizer is 87% by mass or less (that is, the blending ratio of the polyester-based plasticizer is 13% by mass or more), good oil resistance is obtained. The mass ratio of the phthalate ester-based plasticizer to the polyester-based plasticizer in the foam layer may be the same as or different from that in the non-foam layer.
The content of the plasticizer (the total content of the phthalate ester-based plasticizer and the polyester-based plasticizer) in the foam layer is from 60 to 100 parts by mass, and preferably from 65 to 85 parts by mass, with respect to 100 parts by mass of the vinyl chloride-based resin. When the blending amount of the plasticizer is 60 parts by mass or more, a soft texture is obtained. In addition, the viscosity of the resin composition liquid for the foam layer can be suppressed to be low, and processability, particularly processability by a casting method, is improved. When the blending amount of the plasticizer is 100 parts by mass or less, strength can be improved. Further, since the bleeding of the plasticizer can be suppressed, the design property can be improved. The content of the plasticizer in the foam layer may be the same as or different from that in the non-foam layer.
The foam layer can be formed, for example, by adding a foaming agent to the resin composition liquid for the foam layer, and the sense of touch and the texture can be improved. The foaming agent is not particularly limited, and a known foaming agent can be used. From the viewpoint of foaming properties, an organic-based foaming agent is preferably used. Examples of the organic-based foaming agent include azodicarbonamide (ADCA), 2,2′-azodiisobutyronitrile (AIBN), benzenesulfonyl hydrazide, p-toluenesulfonyl hydrazide, 4,4′-oxybis [benzenesulfonyl hydrazide] (OBSH), and N,N′-dinitrosopentamethylene tetramine (DPT). These can be used alone or in combination of two or more thereof.
The expansion ratio of the foam layer is not particularly limited, but is preferably 2 times or less, more preferably 1.1 times or more and 2 times or less, and still more preferably 1.2 times or more and 1.7 times or less. When the expansion ratio of the foam layer is 2 times or less, independent pores are easily formed, and abrasion resistance, bending resistance, and peel strength can be improved.
The thickness of the foam layer is not particularly limited, and may be, for example, from 150 to 370 μm, but is preferably from 190 to 370 μm, and more preferably from 200 to 300 μm. When the thickness of the foam layer is 190 μm or more, a soft texture can be obtained. When the thickness of the foam layer is 370 μm or less, the size of the diameter of the foam cell can be easily adjusted.
In the foam layer, conventionally known additives can be blended, if necessary, within a range that does not impair the physical properties thereof. Examples of such additives include a plasticizer other than the phthalate ester-based plasticizer and polyester-based plasticizer, a thermoplastic resin and thermosetting resin other than the vinyl chloride-based resin, a heat stabilizer, a filler, a pigment, an amine resistant agent, a flame retardant, a conductivity-imparting agent, an antistatic agent, an ultraviolet absorber, a light stabilizer, an antioxidant, a pigment dispersant, a crosslinking agent, and a thickening agents, and these can be used alone or in combination of two or more thereof. Note that specific examples and contents of the heat stabilizer and the amine resistant agent in the foam layer are the same as those in the non-foam layer described above.
In the embodiment, when the foam layer is provided, an adhesive layer may be interposed between the foam layer and the fibrous substrate, or the foam layer may be directly laminated on the fibrous substrate. By interposing the adhesive layer between the fibrous substrate and the foam layer, the adhesiveness between the fibrous substrate and the foam layer can be improved. The adhesive layer may be a non-foam resin layer having no bubbles.
A resin forming the adhesive layer is not particularly limited, and a resin generally used for ordinary vinyl chloride leather can be used. Examples thereof include a polyurethane resin and a vinyl chloride-based resin.
The thickness of the adhesive layer is not particularly limited, and may be, for example, from 20 to 200 μm or from 50 to 150 μm.
In the embodiment, a protective layer may be further provided on the non-foam layer. By providing the protective layer on the non-foam layer, physical properties, particularly abrasion resistance and oil resistance, of the resulting synthetic leather can be improved.
The protective layer preferably contains a polyurethane resin. The polyurethane resin for the protective layer is not particularly limited, and examples thereof include a polyether-based polyurethane resin, a polyester-based polyurethane resin, and a polycarbonate-based polyurethane resin. These polyurethane resins can be used alone or in combination of two or more thereof. Among these, a polycarbonate-based polyurethane resin is preferable as the polyurethane resin for the protective layer from the viewpoint of abrasion resistance.
The form of the polyurethane resin for the protective layer is not particularly limited and may be appropriately selected depending on the application. For example, it may be solvent-based or water-based, and may be a one liquid type or two liquids-curing type. From the viewpoint of environmental protection, the form of the polyurethane resin is preferably water-based.
In the resin composition liquid for the protective layer used for forming the protective layer, an optional component can be blended, if necessary, within a range that does not impair the physical properties of the polyurethane resin. Examples of the optional component include a crosslinking agent, a lubricant, a leveling agent, a thickening agent, a defoaming agent, a light resistant stabilizer, a conductivity-imparting agent, an antistatic agent, a water-repellent agent, an oil-repellent agent, an antiblocking agent, and an antibacterial agent. These can be used alone or in combination of two or more thereof.
The thickness of the protective layer is not particularly limited, and is, for example, preferably from 2 to 30 μm, and more preferably from 5 to 20 μm. When the thickness is 2 μm or more, abrasion resistance can be improved. When the thickness is 30 μm or less, a soft texture can be obtained.
In the embodiment, when the protective layer is provided, an undercoat layer may be interposed between the protective layer and the non-foam layer, or the protective layer may be directly laminated on the non-foam layer. By interposing the undercoat layer between the surface layer and the protective layer, the physical properties of the resulting synthetic leather, particularly, abrasion resistance, thermal yellowing resistance, and oil resistance can be improved.
The undercoat layer preferably contains a polyurethane resin. The polyurethane resin for the undercoat layer is not particularly limited, and examples thereof include a polyether-based polyurethane resin, a polyester-based polyurethane resin, and a polycarbonate-based polyurethane resin. These polyurethane resins can be used alone or in combination of two or more thereof. Among these, a polyester-based polyurethane resin is preferable as the polyurethane resin for the undercoat layer from the viewpoint of thermal yellowing resistance and oil resistance.
The form of the polyurethane resin for the undercoat layer is not particularly limited and may be appropriately selected depending on the application. For example, it may be solvent-based or water-based, and may be a one liquid type or two liquids-curing type. From the viewpoint of environmental protection, the polyurethane resin is preferably water-based.
In the resin composition liquid for the undercoat layer used for forming the undercoat layer, an optional component can be blended, if necessary, within a range that does not impair the physical properties of the polyurethane resin. Examples of the optional component include a resin other than the polyurethane resin (for example, an acrylic resin), a crosslinking agent, a leveling agent, a defoaming agent, and a thickening agent. These can be used alone or in combination of two or more thereof.
The thickness of the undercoat layer is not particularly limited, and may be, for example, from 1 to 20 μm or from 2 to 10 μm.
Next, a method for producing a synthetic leather according to the embodiment is described. The production method is not particularly limited, and the production method similar to that for a conventionally known synthetic leather can be adopted, and examples thereof include a calendering method and a casting method. In one embodiment, in the case of the casting method, the synthetic leather of the embodiment can be produced by performing the following steps in sequence. That is, the production method includes:
As a method of applying the resin composition liquid for the non-foam layer onto the releasable substrate, various conventionally known methods can be adopted, and the method is not particularly limited. Examples thereof can include a method using a knife coater, a comma coater, a roll coater, or a die coater. Among these, applying with a knife coater or a comma coater is preferable from the viewpoint that a uniform thin film layer can be formed.
The releasable substrate is not particularly limited, and may be a substrate having releasability to a vinyl chloride-based resin or a substrate subjected to a release treatment. Examples thereof include a release paper, a release-treated cloth, a water-repellent-treated cloth, an olefin sheet or film made of a polyethylene resin or a polypropylene resin, a fluororesin sheet or film, and a plastic film with a release paper. The releasable substrate may have an uneven pattern, and by using such a releasable substrate, an uneven pattern such as a grained pattern can be formed on the surface of the synthetic leather to impart a design property.
After the resin composition liquid for the non-foam layer is applied to the releasable substrate, a heat treatment is performed as necessary. The heat treatment is performed to promote gelation.
Next, the resin composition liquid for the foam layer is applied onto the non-foam layer. As a method of applying the resin composition liquid for the foam layer, the same method as the method of applying the resin composition liquid for the non-foam layer can be adopted.
Next, the foam layer and the fibrous substrate are laminated. Examples of the lamination method include conventionally known methods such as a transfer method, thermal fusion bonding, thermal compression bonding, and adhesion using an adhesive. When an adhesive is used, the resin composition liquid for the adhesive layer may be applied onto the foam layer, and then the fibrous substrate may be laminated thereon. As a method of applying the resin composition liquid for the adhesive layer, the same method as the method of applying the resin composition liquid for the non-foam layer can be adopted.
Next, the releasable substrate is peeled off from the non-foam layer. By peeling off the releasable substrate, a laminate of the non-foam layer, the foam layer, and the fibrous substrate is obtained.
When the protective layer is formed on the non-foam layer, the protective layer may be formed on the surface of the laminate after the releasable substrate is peeled off as described above. The protective layer may be provided above the non-foam layer with an undercoat layer therebetween, or may be laminated directly on the non-foam layer. The method for applying the resin composition liquid for the undercoat layer to the surface of the non-foam layer is not particularly limited, and the same method as the method of applying the resin composition liquid for the non-foam layer can be used.
As a method of applying the resin composition liquid for the protective layer to the non-foam layer or the undercoat layer in order to form the protective layer, the same method as the method of applying the resin composition liquid for the non-foam layer can be adopted. In addition, it is also possible to adopt an application method using an apparatus such as a spray coater, a gravure coater, a gravure direct printer, a gravure offset printer, or a screen printer.
Next, a heat treatment is performed as necessary. The heat treatment is performed to evaporate the solvent in the resin composition liquid for the protective layer and dry the resin. Further, in the case of using a crosslinking agent which causes a crosslinking reaction by the heat treatment or in the case of using a two liquids-curing type resin, the heat treatment is carried out in order to accelerate the reaction and form a film having sufficient strength.
Next, if necessary, an uneven pattern such as a grained pattern is formed on the non-foam layer (the protective layer when the protective layer is formed). As described above, as a method of forming the uneven pattern after the releasable substrate is peeled off, various conventionally known methods can be adopted, and the method is not particularly limited. Examples thereof can include methods using embossing, vacuum embossing, welder processing, and pinsonic processing.
Thus, the synthetic leather according to one embodiment is obtained. However, the method for producing the synthetic leather of the embodiment is not limited to the method described above.
Hereinafter, the invention is described in more detail with reference to Examples, but the invention is not limited to the following Examples.
Each evaluation item was evaluated according to the following method.
A sample was taken in the size having a width of 25 cm and a length of 35 cm. The sample was placed on a horizontally placed glass plate having a width of 150 mm, a length of 200 mm, and a thickness of 3 mm. Four sheets of 100% cotton gauze (“Bescher gauze 10 m 300-10M” manufactured by Yamatokojo Co., Ltd.) having a size with a width of 20 cm and a length of 25 cm were stacked on the surface of the resin layer (the non-foam layer or the protective layer) of the test piece, and 60 mL of oleic acid (“15745-55” manufactured by Nacalai Tesque, Inc.) was added dropwise thereto through the 100% cotton gauze. A glass plate having a width of 150 mm, a length of 200 mm and a thickness of 3 mm was placed on the 100% cotton gauze. The resultant object was allowed to stand for 72 hours in an air-blowing constant temperature dryer (“DRM620DD” manufactured by ADVANTEC CO., LTD.) adjusted to 80° C. Thereafter, the glass plates and the 100% cotton gauze were removed, and a wiper paper (“KIMWIPE S-200”, manufactured by Nippon Paper Crecia Co., Ltd.) was pressed thereon to remove excess oleic acid.
From the central portion of the obtained sample after the oil resistance test, two test pieces having a size of a width of 30 mm and a length of 120 mm were taken from each of the lengthwise direction (the longitudinal direction) and the lateral direction (the width direction). The test pieces taken from the same direction were overlapped with each other so that the surfaces of the resin layers were on an inner side, and gripped with a Scott type crease-flex tester (Scott Type Crease-Flex Abrasion Tester “CV-10N”, manufactured by Daiei Kagaku Seiki MFG. Co., Ltd.) at a gripping distance of 30 mm. The grips were gradually moved closer to each other so as to be in a state in which the two test pieces opened and separated from each other. After the surfaces of the resin layers of the test pieces were lightly touched, a load of 9.8 N was applied. The tester was moved, and the crease-flex test was performed for 2000 times with a load of 9.8 N, at a gripping distance of 30 mm, and a crease-flex stroke of 50 mm. Thereafter, the state of the test pieces were observed, and the evaluation was made according to the following criteria.
One test piece having a size of a width of 70 mm and a length of 300 mm was taken from each of the lengthwise and lateral directions, and a polyurethane foam having a size of a width of 70 mm, a length of 300 mm and a thickness of 10 mm was attached to the back surface. The resultant object was fixed to a plane abrasion tester “T-TYPE” (manufactured by by Daiei Kagaku Seiki MFG. Co., Ltd.) with a wire having a diameter of 4.5 mm placed at the center of the lower surface of the polyurethane foam, and an abrasion test was conducted by applying a load of 9.8 N to a friction element covered with a cotton cloth so that the abrasion element reciprocated on the wire in parallel with the wire. The friction element was reciprocated 10,000 times between a distance of 140 mm on the surface of the test piece at a speed of 60 reciprocations/minutes. The surface condition of the test piece after the abrasion test was observed and evaluated according to the following criteria.
The viscosities of the resin composition liquid for the non-foam layer and the resin composition liquid for the foam layer were measured with a BII type viscometer (BHII type, manufactured by Toki Sangyo Co., Ltd., rotor No. 3, 10 rpm, 23° C.), and evaluated according to the following criteria. When the evaluation is A, processability is excellent.
Sensory evaluation was conducted by panelists, and evaluated according to the following criteria. The evaluation of B or higher is acceptable.
As a substrate, a circular knitted fabric (polyester fiber, a thickness of 580 μm, a mass per unit area of 120 g/m2) was prepared.
Preparation method: After mixing the vinyl chloride-based resin and the plasticizer, the Ca—Zn-based heat stabilizer, the pigment, and the amine resistant agent were added and mixed to obtain a resin composition liquid for a non-foam layer. The viscosity (23° C.) of the resin composition liquid for the non-foam layer was 4000 mPa·s.
Preparation method: After mixing the vinyl chloride-based resin and the plasticizer, the Ca—Zn-based heat stabilizer, the pigment, the amine resistant agent, and the organic-based foaming agent were added and mixed to obtain a resin composition liquid for a foam layer. The viscosity (23° C.) of the resin composition liquid for the foam layer was 4000 mPa·s.
Preparation method: After mixing the vinyl chloride-based resin and the plasticizer, the Ca—Zn-based heat stabilizer and the flame retardant were added and mixed, and the crosslinking agent was further added and mixed to obtain a resin composition liquid for an adhesive layer. The viscosity of the resin composition liquid for the adhesive layer was 65000 mPa's (BII type viscometer (BHII type), manufactured by Toki Sangyo Co., Ltd., rotor No. 6, 10 rpm, 23° C.).
Preparation method: The crosslinking agent was added to and mixed with the polyurethane resin to obtain a resin composition liquid for an undercoat layer. The viscosity of the resin composition liquid for the undercoat layer was 3000 mPa's (BII type viscometer (BHII type), manufactured by Toki Sangyo Co., Ltd., rotor No. 3, 10 rpm, 23° C.).
Preparation method: After mixing the lubricant with the polyurethane resin, the crosslinking agent was added and mixed to obtain a resin composition liquid for a protective layer. The viscosity of the resin composition liquid for the protective layer was 1000 mPa's (BII type viscometer (BHII type), manufactured by Toki Sangyo Co., Ltd., rotor No. 3, 10 rpm, 23° C.).
The resin composition liquid for the non-foam layer prepared in accordance with the formulation 1 was applied to a flat release paper (a product name “VX-12”, manufactured by LINTEC Corporation) in a sheet form by a comma coater so as to have an application thickness of 160 μm, and heat treatment was performed in a dryer at 180° C. for 2 minutes and 30 seconds to form the non-foam layer.
Next, the resin composition liquid for the foam layer prepared in accordance with the formulation 2 was applied in a sheet form onto the non-foam layer formed on the release paper by a comma coater so as to have an application thickness of 140 μm, and heat treatment was performed in a dryer at 200° C. for 2 minutes and 30 seconds to form the foam layer.
Next, the resin composition liquid for the adhesive layer prepared in accordance with the formulation 3 was applied onto the foam layer in a sheet form by a knife coater so as to have an application thickness of 90 μm. Thereafter, the fibrous substrate was superposed thereon, and the resultant object was treated in a dryer at 180° C. for 2 minutes and 30 seconds to perform formation of the adhesive layer and attaching of the fibrous substrate. Thereafter, the release paper was peeled off to obtain a laminate including the non-foam layer, the foam layer, the adhesive layer, and the fibrous substrate.
Next, the resin composition liquid for the undercoat layer prepared in accordance with the formulation 4 was applied in a sheet form to the surface of the non-foam layer after the release paper was peeled off by a gravure coater so as to have an application thickness of 12 μm, and heat treatment was performed in a dryer at 130° C. for 2 minutes to form the undercoat layer.
Next, the resin composition liquid for the protective layer prepared in accordance with the formulation 5 was applied to the surface of the undercoat layer in a sheet form by a gravure coater so as to have an application thickness of 15 μm, and heat treatment was performed in a dryer at 130° C. for 1 minute to form the protective layer.
Next, after the obtained laminate was preheated with an infrared heater at 170° C. for 15 seconds, a grained pattern was formed on the front surface of the protective layer with a vacuum embossing machine to obtain a synthetic leather of Example 1. The thickness of the non-foam layer was 160 μm, the expansion ratio of the foam layer was 1.5 times, and the thickness of the foam layer was 210 μm.
The thickness of each resin layer is a value obtained by observing a vertical cross-section of the synthetic leather with a microscope (Digital HF Microscope VH-8000, manufactured by Keyence Corporation), measuring the thickness at arbitrary 10 locations, and calculating the average value thereof.
Regarding the expansion ratio of the foam layer, after the resin composition liquid for the foam layer was applied onto the release paper in a sheet form with a comma coater so as to have an application thickness of 140 μm, the resultant object was dried at 200° C. for 2 minutes and 30 seconds. The film thickness of the obtained foam sheet was measured and calculated by the following formula.
Expansion ratio (times)=film thickness of foam sheet/{application thickness (140 μm)×solid fraction of resin composition liquid for foam layer}
A synthetic leather was obtained in the similar manner as in Example 1 except that the formulation of the resin composition for each resin layer was changed as shown in Tables 1 to 4. Regarding the solid content in Tables 1 to 4, “%” is % by mass. Note that regarding the polyester-based plasticizer, the viscosity and the number average molecular weight of the adipic acid-based polyesters in Tables 1 to 4 are as described in Tables 1 to 4. Specifically, each of the adipic acid-based polyesters in Tables 1 to 4 was obtained by polycondensation of adipic acid with 1,3-butanediol and 1,4-butanediol. In Example 7, an adipic acid-based polyester having a number average molecular weight of 800 and a viscosity (25° C.) of 200 mPa's was used. In Example 8, an adipic acid-based polyester having a number average molecular weight of 2200 and a viscosity (25° C.) of 5000 mPa's was used. The adipic acid-based polyesters used in other Examples and Comparative Examples are the same as those described in Example 1.
Evaluation results for Examples 1 to 14 and Comparative Examples 1 to 6 are as shown in Tables 1 to 4. In Comparative Example 1, the mass ratio of the phthalate ester-based plasticizer to the polyester-based plasticizer contained in the non-foam layer and the foam layer was 93:7, and the blending amount of the phthalate ester-based plasticizer was large. Therefore, oil resistance was poor. In Comparative Examples 3 to 5, since only the phthalate ester-based plasticizer was contained in the non-foam layer and/or the foam layer, oil resistance was poor. In Comparative Example 2, the mass ratio of the phthalate ester-based plasticizer to the polyester-based plasticizer contained in the non-foam layer and the foam layer was 67:33, and the content of the polyester-based plasticizer was large. Therefore, although oil resistance was good, generation of bubbles occurred, and processability was poor. In Comparative Example 6, the content of the plasticizer was small, and processability was poor. In contrast, Examples 1 to 14 were excellent in oil resistance and processability.
The invention includes the following embodiments.
[1] A synthetic leather including: a fibrous substrate, a foam layer containing a vinyl chloride-based resin and a plasticizer, and a non-foam layer containing a vinyl chloride-based resin and a plasticizer, in this order, in which, in each of the foam layer and the non-foam layer, a content of the plasticizer is from 60 to 100 parts by mass with respect to 100 parts by mass of the vinyl chloride-based resin, the plasticizer contains a phthalate ester-based plasticizer and a polyester-based plasticizer, and a mass ratio of the phthalate ester-based plasticizer to the polyester-based plasticizer is from 73:27 to 87:13 (preferably from 77:23 to 83:17).
[2] The synthetic leather according to [1], in which the polyester-based plasticizer in the foam layer and the non-foam layer has a number average molecular weight of from 500 to 2500 (preferably from 1200 to 2000).
[3] The synthetic leather according to [1] or [2], in which the polyester-based plasticizer in the foam layer and the non-foam layer has a viscosity at 25° C. of from 150 to 5000 mPa's (preferably from 2000 to 5000 mPas).
[4] The synthetic leather according to any one of [1] to [3], in which the polyester-based plasticizer in the foam layer and the non-foam layer is at least one selected from the group consisting of an adipic acid-based polyester, a sebacic acid-based polyester, and a phthalic acid-based polyester, and is preferably an adipic acid-based polyester plasticizer.
[5] The synthetic leather according to any one of [1] to [4], in which the phthalate ester-based plasticizer in the foam layer and the non-foam layer is at least one selected from the group consisting of dibutyl phthalate, dioctyl phthalate, dinonyl phthalate, diisononyl phthalate, diisodecyl phthalate, ditridecyl phthalate, diundecyl phthalate, benzyl butyl phthalate, nonyl undecyl phthalate, and dialkyl phthalate (C9 to C11), and preferably dialkyl phthalate (C9 to C11).
[6] The synthetic leather according to any one of [1] to [5], in which the non-foam layer has a thickness of from 100 to 300 μm (preferably from 130 to 250 μm).
[7] The synthetic leather according to any one of [1] to [6], in which each of the foam layer and the non-foam layer further includes a heat stabilizer (preferably a calcium salt of an organic acid and/or a zinc salt of an organic acid), and preferably a content of the heat stabilizer is from 0.1 to 10 parts by mass (preferably from 0.5 to 5 parts by mass) with respect to 100 parts by mass of the vinyl chloride-based resin.
[8] The synthetic leather according to any one of [1] to [7], in which each of the foam layer and the non-foam layer further includes an amine resistant agent (preferably a perchlorate), and preferably a content of the amine resistant agent is from 0.05 to 5 parts by mass (preferably from 0.1 to 2 parts by mass) with respect to 100 parts by mass of the vinyl chloride-based resin.
[9] The synthetic leather according to any one of [1] to [8], in which the foam layer is formed by adding a foaming agent (preferably an organic-based foaming agent) to a resin composition liquid for the foam layer.
[10] The synthetic leather according to any one of [1] to [9], in which an expansion ratio of the foam layer is 2 times or less (preferably 1.1 times or more and 2 times or less, more preferably 1.2 times or more and 1.7 times or less).
[11] The synthetic leather according to any one of [1] to [10], in which the foam layer has a thickness of from 150 to 370 μm (preferably from 190 to 370 μm, and more preferably from 200 to 300 μm).
[12] The synthetic leather according to any one of [1] to [11], further comprising an adhesive layer containing a polyurethane resin and/or a vinyl chloride-based resin between the fibrous substrate and the foam layer.
[13] The synthetic leather according to any one of [1] to [12], further comprising a protective layer containing a polyurethane resin (preferably a polycarbonate-based polyurethane resin) on or above the non-foam layer.
[14] The synthetic leather according to [13], in which the protective layer has a thickness of from 2 to 30 μm (preferably from 5 to 20 μm).
[15] The synthetic leather according to or [14], further comprising an undercoat layer containing a polyurethane resin (preferably a polyester-based polyurethane resin) between the non-foam layer and the protective layer.
[16] The synthetic leather according to any one of [1] to [15], in which the non-foam layer is a resin layer formed by applying a resin composition liquid for the non-foam layer onto a releasable substrate, the foam layer is a resin layer formed by applying a resin composition liquid for the foam layer onto the non-foam layer formed on the releasable substrate, each of the resin composition liquid for the non-foam layer and the resin composition liquid for the foam layer contains a vinyl chloride-based resin and a plasticizer containing a phthalate ester-based plasticizer and a polyester-based plasticizer at a mass ratio of from 73:27 to 87:13, and a content of the plasticizer is from 60 to 100 parts by mass with respect to 100 parts by mass of the vinyl chloride-based resin.
[17] The synthetic leather according to any one of [1] to [16], in which an uneven pattern (preferably a grained pattern) is provided on a front surface.
Note that in the various numerical ranges described in the specification, the upper limits and the lower limits thereof can be arbitrarily combined, and all of the combinations are described in the specification as preferable numerical ranges. In addition, the description of a numerical range of “from X to Y” means X or more and Y or less unless otherwise specified.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-214806 | Dec 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/037430 | 10/6/2022 | WO |
