synthetic leather

Abstract

To provide a synthetic leather, specifically, a vinyl chloride-based synthetic leather with suppressed bleed-out phenomenon of a plasticizer and improved chemical resistance, which does not easily generate cracks even under a low temperature environment and has good cold resistance.SOLUTION: A synthetic leather has a skin layer and a base cloth. The skin layer contains vinyl chloride-based resin and plasticizer. The plasticizer contains polyester plasticizer having number average molecular weight of 800 or more and 4000 or less. The synthetic leather is configured to have the polyester plasticizer of 10% by mass or higher and 80% by mass or less in the plasticizer of 100% by mass contained in the skin layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to synthetic leather having a skin containing a vinyl chloride resin. [Background technology]

[0002] As shown in Patent Document 1, synthetic leather is composed of a base fabric and a skin layer laminated on the surface of the base fabric. The skin layer is a resin layer composed of a base resin. Examples of the base resin include vinyl chloride resins and polyurethane resins. Among these, vinyl chloride resins are excellent as the base resin due to their advantages of low cost and ease of processing. Therefore, synthetic leathers having a skin layer whose base resin is vinyl chloride resin are widely used in various industrial fields. Such skin layers whose base resin is vinyl chloride resin generally contain a plasticizer to exhibit good flexibility.

[0003] For example, synthetic leathers with a surface layer made of a vinyl chloride resin as a base resin are used in a variety of applications, including vehicle interior materials, furniture such as sofas, clothing such as shoes and clothes, small bags such as bags, and outdoor products such as tent awnings. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-228258 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, as the applications of synthetic leather with a skin made of a vinyl chloride resin as the base resin (hereinafter referred to as PVC synthetic leather or simply synthetic leather) expand, there is a growing demand for further improvements in the physical properties of PVC synthetic leather. Specifically, when PVC synthetic leather is used in a low-temperature environment, there is a problem that the surface cracks with even a slight impact or bending. Therefore, there is a demand for improved cold resistance of PVC synthetic leather.

[0006] On the other hand, vinyl chloride synthetic leather is understood to be able to maintain a good condition in a temperature environment above room temperature without the above-mentioned problems. However, vinyl chloride synthetic leather has the following problems when used. As mentioned above, PVC synthetic leather is used for a variety of purposes and is often exposed to human contact. Therefore, oily substances such as human sebum, makeup, and suntan cream are likely to adhere to PVC synthetic leather upon contact. When PVC synthetic leather with oily substances adhered to it is left in a relatively high-temperature environment at room temperature or higher for a long period of time, a bleed-out phenomenon may occur, in which the plasticizer contained in the surface layer rises to the surface of the synthetic leather. This plasticizer bleed-out phenomenon hardens the surface layer, degrading the synthetic leather's texture and making the surface susceptible to cracking even when the synthetic leather is subjected to impact or bending. In other words, PVC synthetic leather has had problems with chemical resistance due to oily substances and the like. This problem can occur even when a surface protective layer or the like is formed on the surface of the surface layer.

[0007] The present invention has been made in view of the above-mentioned problems. That is, an object of the present invention is to provide a vinyl chloride synthetic leather that is resistant to cracking and has good cold resistance even in low-temperature environments, and that has improved chemical resistance due to suppressed bleeding out of plasticizers. [Means for solving the problem]

[0008] The synthetic leather of the present invention comprises a surface layer and a base fabric. A surface protective layer provided on the surface of the skin layer opposite to the base fabric;The synthetic leather has a surface layer containing a vinyl chloride resin and a plasticizer, and the plasticizer contains a polyester plasticizer having a number average molecular weight of 800 or more and 4000 or less, and the polyester plasticizer accounts for 10% by mass or more and 80% by mass or less of 100% by mass of the plasticizer contained in the surface layer. The average acid value (KOHmg / g) of the plasticizer contained in the surface layer is 0.1 or more, the surface protective layer contains a polyurethane resin and a crosslinking agent, the proportion of the crosslinking agent blended per 100 parts by mass of the polyurethane resin is 2 parts by mass or more and 20 parts by mass or less, and the crosslinking agent contains an isocyanate. It is characterized by: [Effects of the Invention]

[0009] The synthetic leather of the present invention having the above-described configuration has improved cold resistance and chemical resistance, and therefore the temperature conditions of the usage environment are substantially alleviated, making the synthetic leather of the present invention suitable for a variety of uses. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a first embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of a second embodiment of the present invention. [Figure 3] FIG. 10 is a cross-sectional view of a variant of the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] The synthetic leather of the present invention comprises a surface layer and a base fabric. In the present invention, the surface layer contains a vinyl chloride resin and a plasticizer. The plasticizer includes a polyester plasticizer having a number-average molecular weight of 800 to 4000, and the polyester plasticizer is contained in an amount of 10 to 80% by mass relative to 100% by mass of the plasticizer contained in the surface layer. The synthetic leather of the present invention includes artificial leathers that use nonwoven fabric or special nonwoven fabric as a base fabric, as well as other synthetic leathers that do not use nonwoven fabric or special nonwoven fabric as a base fabric. Here, special nonwoven fabric refers to a base fabric that is based on a member having a fiber layer with a random three-dimensional structure and is impregnated with polyurethane or a similar substance.

[0012] The synthetic leather of the present invention having the above-described configuration exhibits good cold resistance and suppresses the bleeding of plasticizers even when exposed to relatively high temperatures above room temperature with oily substances such as human sebum adhering to the surface. Therefore, the synthetic leather of the present invention can provide excellent quality in applications where a wide range of temperature environments during use and human contact are expected, such as vehicle interior materials, clothing, and outdoor products. In relation to the present invention, the suppression of bleeding of plasticizers even when oily substances are adhering to the leather is sometimes referred to as excellent chemical resistance. The present invention will be described in more detail below with reference to embodiments.

[0013] First Embodiment 1 shows a schematic cross-sectional view of synthetic leather 110 according to a first embodiment of the present invention, cut in the thickness direction. The synthetic leather 110 includes a surface layer 10 and a base fabric 20. In this embodiment, the surface layer 10 and the base fabric 20 are bonded together by an adhesive layer 40. A surface protection layer 30 is provided on the surface side of the surface layer 10.

[0014] (epidermal layer 10) The skin layer 10 contains a vinyl chloride resin and a plasticizer. The skin layer 10 constitutes the surface of the synthetic leather 110 and may be provided with a grained pattern or the like to create a leather-like appearance. The grained pattern referred to here refers to a decorative pattern or design on the surface of a component. The present invention encompasses both an embodiment in which the skin layer 10 is disposed on the outermost surface of the synthetic leather 110 and an embodiment in which the skin layer 10 is disposed close to the outermost surface of the synthetic leather 110. In other words, the present invention encompasses an embodiment in which an optional layer is disposed further on the surface side than the skin layer 10. Specifically, this embodiment illustrates an embodiment in which a surface protective layer 30 is provided on the surface side of the skin layer 10. Synthetic leather 110 having a skin layer 10 containing a vinyl chloride resin encompasses a component known as PVC leather.

[0015] PVC resin: The skin layer 10 contains a vinyl chloride resin, preferably a vinyl chloride resin as a base resin. Here, the base resin refers to a resin contained in an amount of more than 50% by mass of 100% by mass of the resin constituting any layer (e.g., the skin layer 10). The vinyl chloride resin contained in the skin layer 10 refers to a resin containing structural units derived from vinyl chloride. Specific examples include a vinyl chloride homopolymer, a copolymer made of a vinyl chloride monomer and another monomer copolymerizable therewith, or a blend of these resins. Examples of other monomers copolymerizable with the vinyl chloride monomers include ethylene, propylene, vinyl acetate, vinylidene chloride, acrylic acid, acrylic acid esters, methacrylic acid, methacrylic acid esters, maleic acid, acrylonitrile fumarate, etc. The vinyl chloride resin contained in the skin layer 10 may be one type or two or more types.

[0016] Skin layer 10 may contain a vinyl chloride resin in combination with other resins, or may be composed essentially of vinyl chloride resin alone. The vinyl chloride resin contained in skin layer 10 preferably accounts for more than 50% by mass, more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably substantially 100% by mass, of the 100% by mass of the resin that constitutes skin layer 10.

[0017] The thickness of the skin layer 10 is not particularly limited, but is preferably 10 μm or more, more preferably 100 μm or more from the viewpoint of durability, and is preferably in the range of 400 μm or less from the viewpoint of texture and flexibility.

[0018] Plasticizer: The skin layer 10 contains a plasticizer. The polyester plasticizer is contained in a ratio of 10% by mass to 80% by mass of the plasticizer (100% by mass). As such a polyester plasticizer, a polyester plasticizer having a number average molecular weight of 800 to 4000 is selected. By containing the polyester plasticizer, which is a polymer plasticizer, the skin layer 10 not only effectively exhibits flexibility similar to that of natural leather, but also exhibits the following excellent properties.

[0019] That is, by including a predetermined proportion of a polyester plasticizer having a number-average molecular weight of 800 to 4000 in the skin layer 10 made of a vinyl chloride resin, the bleed-out phenomenon, in which the plasticizer contained in the skin layer 10 rises to the surface of the synthetic leather 110, is effectively suppressed, even when the synthetic leather 110 having an oily substance attached thereto is left in a relatively high-temperature atmosphere above room temperature for a long period of time. From the viewpoint of more effectively suppressing the bleed-out phenomenon, the number-average molecular weight of the polyester plasticizer used is preferably 1200 to 3000, and more preferably 1500 to 2000.

[0020] The number average molecular weight of the plasticizer described above is measured by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as an eluent, and can be obtained as a value converted into standard polystyrene.

[0021] Furthermore, by including 10% by mass or more of the polyester plasticizer relative to 100% by mass of the plasticizer contained in the epidermis layer 10, the above-mentioned bleed-out phenomenon can be effectively suppressed, and a synthetic leather 110 with excellent chemical resistance can be provided. In particular, the epidermis layer 10 has excellent chemical resistance when higher fatty acids such as oleic acid are attached, and therefore the above-mentioned bleed-out phenomenon can be effectively suppressed even when sebum, cosmetics, sunscreen cream, etc. are attached. From the viewpoint of improving chemical resistance, the content of the polyester plasticizer is preferably 20% by mass or more, more preferably 40% by mass or more, and even more preferably 60% by mass or more.

[0022] On the other hand, by including 80% by mass or less of the polyester plasticizer in 100% by mass of the plasticizer contained in the skin layer 10, it is possible to provide a synthetic leather 110 that has excellent cold resistance while maintaining good chemical resistance. From the viewpoint of improving cold resistance, the content of the polyester plasticizer is preferably 70% by mass or less. The synthetic leather 110 having the skin layer 10 is resistant to breakage even when subjected to impact or bending in cold regions, for example, at temperatures of -30°C or below, and has excellent cold resistance.

[0023] Examples of polyester plasticizers contained in the skin layer 10 include phthalic acid polyester plasticizers, adipic acid polyester plasticizers, sebacic acid polyester plasticizers, and maleic acid polyester plasticizers. That is, examples of the polyester plasticizer used in the present invention include esters of polycarboxylic acids (dicarboxylic acids) such as phthalic acid, adipic acid, sebacic acid, or maleic acid with polyalcohols.

[0024] Examples of plasticizers other than polyester-based plasticizers contained in the surface layer 10 include trimellitic acid-based plasticizers, phthalic acid-based plasticizers, linear dibasic acid-based plasticizers, and phosphoric acid-based plasticizers. From the viewpoint of versatility, phthalic acid-based plasticizers are preferred. More specifically, for example, trimellitic acid-based plasticizers such as tri-n-octyl trimellitate, tri-(2-ethylhexyl) trimellitate, triisooctyl trimellitate, triisodecyl trimellitate, and di-n-octyl-n-decyl trimellitate; dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, didodecyl phthalate, butyl benzyl phthalate; and diisobutyl phthalate. Examples of the plasticizer include phthalic acid-based plasticizers such as decyl phthalate, dihexyl phthalate, and diisononyl phthalate; linear dibasic acid-based plasticizers such as dioctyl adipate, diisodecyl adipate, dibutyl sebacate, and dioctyl sebacate; and phosphate-based plasticizers such as tributyl phosphate, tricresyl phosphate, triphenyl phosphate, trichloroethyl phosphate, trioctyl phosphate, and diphenyl cresyl phosphate. In the present invention, plasticizers containing an ester bond and having a number average molecular weight of less than 800 are recognized as plasticizers other than the polyester-based plasticizers used in the present invention described above.

[0025] The plasticizer other than the polyester-based plasticizer contained in the surface layer 10 is 20% by mass or more and 90% by mass or less, and preferably 30% by mass or more and 80% by mass or less, based on 100% by mass of the plasticizer contained in the surface layer 10.

[0026] The average acid value (KOH mg / g) of all the plasticizers contained in the skin layer 10 is preferably 0.1 or more, and more preferably 0.15 or more. In the present invention, the acid value refers to the number of milligrams (mg) of potassium hydroxide equivalent to the hydroxyl groups in 1 g of sample, and the average acid value of the plasticizer refers to the sum of the values ​​obtained by multiplying the acid value of each plasticizer used in the skin layer by the blending ratio of each plasticizer (blending ratio when the total plasticizer is 100 mass %).

[0027] Ratio of vinyl chloride resin to polyester plasticizer in skin layer 10: The blending ratio of the vinyl chloride resin contained as the base resin in the skin layer 10 to the polyester plasticizer can be determined as appropriate. For example, the amount of polyester plasticizer with a number-average molecular weight of 800 to 4000 is preferably adjusted to 10 to 120 parts by weight, and more preferably 30 to 100 parts by weight, per 100 parts by weight of the vinyl chloride resin contained as the base resin. In particular, blending the plasticizer in the above range with the skin layer 10 containing the vinyl chloride resin as the base resin can bring the elasticity and flexibility of the synthetic leather 110 closer to those of natural leather. If less than 10 parts by mass of polyester plasticizer is blended with 100 parts by mass of base resin, the elasticity and flexibility of skin layer 10 may not be fully exhibited. On the other hand, if more than 120 parts by mass is blended, the effect of further improving the elasticity and flexibility of skin layer 10 may not be achieved, and in addition, there is a risk of a decrease in strength and deterioration of workability.

[0028] Other additives: In addition to the resin and plasticizer, additives may be added to the skin layer 10 as appropriate within the scope of the present invention. Examples of such additives include stabilizers, fillers, flame retardants, and pigments.

[0029] (Base fabric 20) Next, the base fabric 20 will be described. The base fabric 20 is a layer for supporting the skin layer 10. Any base fabric commonly used for synthetic leather or artificial leather can be used for the base fabric 20. Examples include knitted fabrics, woven fabrics, nonwoven fabrics, etc. made of a single fiber selected from synthetic fibers such as polyester, polyamide, polyacrylonitrile, nylon, etc., natural fibers such as cotton and linen, and regenerated fibers such as rayon and acetate, or blends of these fibers. FIG. 1 illustrates a knitted fabric made of warp yarns 210 and weft yarns 220 as the base fabric 20. The base fabric 20 may be brushed or unbrushed.

[0030] The thickness of the base fabric 20 is not particularly limited, but is suitably in the range of, for example, 400 μm or more and 1000 μm or less.

[0031] (Surface protective layer 30) In the synthetic leather 110 of this embodiment, a surface protection layer 30 is provided on the surface of the skin layer 10 opposite to the base fabric 20 . The surface protective layer 30 is composed of an appropriately selected resin. For example, the surface protective layer 30 is composed of a polyurethane resin and a crosslinking agent. The surface protective layer 30 is a layer that protects the surface of the skin layer 10 and can improve the abrasion resistance of the synthetic leather 110. A polyurethane resin refers to a resin that contains a urethane bond in its molecule, and more specifically, a resin that has a urethane bond in the repeating unit of its main chain.

[0032] The polyurethane resin constituting the surface protective layer 30 is a mixture of a polyol component and a polyol component. Isocyanate Any polyurethane resin may be used as long as it is formed by reacting the above components and can form a layer suitable for protecting the surface side of the synthetic leather 110. One example is a water-based polyurethane resin. A water-based polyurethane resin is a polyurethane resin that has hydrophilic groups and can be dissolved or emulsified in water. Examples of such water-based polyurethane resins include polyurethanes that have hydrophilic groups (anionic hydrophilic groups, cationic hydrophilic groups, or nonionic hydrophilic groups) in the molecule, or polyurethanes to which hydrophilic segments have been added. Among water-based polyurethane resins, polycarbonate-based polyurethane resins are preferred from the standpoints of durability, abrasion resistance, and hydrolysis resistance. Polycarbonate-based polyurethanes can be obtained, for example, by polyaddition reaction of polycarbonate-based diol and polyisocyanate.

[0033] The crosslinking agent may be any agent that can improve the physical properties of the polyurethane resin by causing self-crosslinking or three-dimensional crosslinking of the polyurethane resin, and examples thereof include carbodiimide-based crosslinking agents, isocyanate-based crosslinking agents, and oxazoline-based crosslinking agents.

[0034] One of the more preferred aspects of this embodiment, which includes a surface protective layer 30, is an aspect in which the average acid value (KOH mg / g) of the plasticizer contained in the surface layer 10 is 0.1 or more, and the surface protective layer 30, which is made of a polyurethane-based resin, contains an isocyanate-based crosslinking agent as a crosslinking agent. The above embodiment provides synthetic leather 110 with particularly excellent abrasion resistance. While the reason for this improved abrasion resistance is unclear, it is believed that the hydroxyl groups contained in surface layer 10 and the isocyanate contained in surface protective layer 30 react with each other near the interface between surface protective layer 30 and surface layer 10, strengthening the adhesion between surface protective layer 30 and surface protective layer 10. From the perspective of the improved abrasion resistance described above, in the above embodiment, the average acid value of the plasticizer contained in surface layer 10 is preferably 0.15 or higher. For example, synthetic leathers used in vehicle seats are subject to repeated rubbing against the user's skin and clothing. Therefore, the synthetic leather of this embodiment, which has excellent abrasion resistance, is suitable for use in vehicle seats. Of course, the synthetic leather of this embodiment can also be used in a variety of other technical fields.

[0035] The proportion of the crosslinking agent to be blended with respect to 100 parts by mass of the polyurethane resin contained in the surface protective layer 30 is not particularly limited, but is preferably, for example, 2 parts by mass or more and 20 parts by mass or less. If the crosslinking agent is less than 2 parts by mass, there is a risk that the abrasion resistance will be insufficient, and if it exceeds 20 parts by mass, there is a risk that the surface protective layer 30 will become hard and the texture will be impaired.

[0036] (adhesive layer 40) The skin layer 10 and the base fabric 20 of the present embodiment described above are bonded together by an adhesive layer 40 . The adhesive layer 40 is a layer that adheres another layer (skin layer 10 in FIG. 1 ) provided on one side of the base fabric 20. The resin that constitutes the adhesive layer 40 may be selected from resins that can be used as adhesives, such as polyurethane resins, vinyl chloride resins, or polyolefin resins. In particular, in this embodiment, since the skin layer 10 containing a vinyl chloride resin is adhered to the base fabric 20, the adhesive layer 40 is preferably also a layer containing a vinyl chloride resin.

[0037] In other embodiments, the adhesive layer 40 can be omitted as appropriate. For example, a foam layer can be formed on the surface of one of the base fabric 20 and the skin layer 10, and the other member can be quickly laminated on the foam layer while it is still in a semi-cured state, thereby adhering the two together. The foam adhesive layer, which also serves as an adhesive layer, will be described in more detail in the second embodiment below. In another embodiment, the skin layer 10 can be first formed on a release paper, and the base fabric 20 can be laminated on the semi-cured skin layer 10, thereby adhering the two together without the adhesive layer 40.

[0038] The thickness of the adhesive layer 40 is not particularly limited, but layer From the viewpoint of not impairing the flexibility of 10 and achieving sufficient adhesion, the thickness is preferably in the range of 50 μm or more and 250 μm or less.

[0039] Second Embodiment A second embodiment of the present invention will now be described. Fig. 2 shows a schematic cross-sectional view of synthetic leather 120 according to the second embodiment cut in the thickness direction. Fig. 3 shows a schematic cross-sectional view of synthetic leather 130, which is a variation of synthetic leather 120 according to the second embodiment cut in the thickness direction.

[0040] The synthetic leather 120 includes a foamed adhesive layer 50 between the surface layer 10 and the base fabric 20. In this embodiment, the surface layer 10 and the base fabric 20 are bonded together by this foamed adhesive layer 50, and a surface protective layer 30 is provided on the surface side of the surface layer 10. The synthetic leather 120 is configured similarly to the synthetic leather 110, except that it includes the foamed adhesive layer 50 instead of the adhesive layer 40 in the synthetic leather 110 described above. Therefore, the synthetic leather 120 will be described in particular with regard to the foamed adhesive layer 50, and the description of the first embodiment will be referred to as appropriate for the other configurations.

[0041] The foam adhesive layer 50 is a foam resin layer with adhesive properties that not only bonds the skin layer 10 and the base fabric 20 together, but also imparts shock absorption and flexibility to the synthetic leather 120. In other words, the synthetic leather 120 not only has excellent cold resistance and chemical resistance, which are the desired objectives of the present invention, but also has shock absorption and flexibility, making it highly suitable for use as a surface component for vehicle seats, for example.

[0042] The foamed adhesive layer 50 is a resin layer having a large number of bubbles therein. The bubbles may be closed, or some or all of them may be open. The resin constituting the foamed adhesive layer 50 is not particularly limited and may be appropriately selected from foamable resins. For example, a foamed polyurethane resin layer or a foamed vinyl chloride resin layer is suitable for the foamed adhesive layer 50.

[0043] In particular, a preferred embodiment is one in which foamed adhesive layer 50, which is provided between surface layer 10 containing a vinyl chloride resin and a plasticizer and base fabric 20, contains a vinyl chloride resin and a plasticizer. In this embodiment, the plasticizer contained in foamed adhesive layer 50 preferably contains a polyester plasticizer having a number average molecular weight of 800 to 4000, and more preferably, the polyester plasticizer accounts for 10% by mass to 80% by mass of 100% by mass of the plasticizer contained in foamed adhesive layer 50. In this way, since the foamed adhesive layer 50 and the adjacent skin layer 10 are each composed of a vinyl chloride resin and a plasticizer, the cold resistance and chemical resistance of the synthetic leather 120 are further improved, and synthetic leather with superior shock absorption and flexibility can be provided.

[0044] For details of the vinyl chloride resin and plasticizer that can be used in the foamed adhesive layer 50, please refer to the description of the vinyl chloride resin and plasticizer used in the skin layer 10 in the first embodiment, and therefore a detailed explanation will be omitted here.

[0045] The method for forming the foamed adhesive layer 50 is not particularly limited. To form the foamed adhesive layer 50, which is a foamed polyurethane-based resin layer, for example, a surface layer 10 is first formed on a release paper, and a coating liquid containing a foaming agent (water) and a polyurethane-based resin-forming composition is applied to the surface layer 10. The coating is then heated to a moderate temperature to react the isocyanate groups in the polyurethane-based resin-forming composition with the water to generate carbon dioxide, and the isocyanate reacts with the polyol to harden the composition. This allows the formation of a foamed polyurethane-based resin layer containing bubbles formed by the incorporation of carbon dioxide into the urethane-based polymer. A laminate including the surface layer 10, the foamed adhesive layer 50 made of a foamed polyurethane-based resin layer, and the base fabric 20 can be formed by attaching the base fabric 20 to the foamed polyurethane-based resin layer while it is still unhardened. A surface protective layer 30 is then formed on the surface side of the surface layer 10 of the laminate to obtain synthetic leather 120.

[0046] Furthermore, when forming a foamed adhesive layer 50 that is a foamed vinyl chloride resin layer, for example, the surface layer 10 can be formed in advance on release paper, a coating liquid containing a foaming agent and a vinyl chloride resin can be applied to the surface layer 10, and then the surface layer 10 can be heated to foam the foaming agent and form a foamed vinyl chloride resin layer containing fine bubbles. By attaching the base fabric 20 to the foamed vinyl chloride resin layer while it is still uncured, a laminate can be formed that includes the surface layer 10, the foamed adhesive layer 50 made of a foamed vinyl chloride resin layer, and the base fabric 20. By forming a surface protective layer 30 on the surface side of the surface layer 10 in the laminate, synthetic leather 120 can be obtained.

[0047] The thickness of the foamed adhesive layer 50 is not particularly limited, but is preferably in the range of 50 μm to 500 μm, for example. If the thickness is less than 50 μm, the adhesive strength may be poor, and if it exceeds 500 μm, the texture may be deteriorated.

[0048] The second embodiment is an embodiment in which a layer containing a foamed resin is provided between the skin layer 10 and the base fabric 20. As shown in FIG. 3 , the foamed adhesive layer 50 of the synthetic leather 120 can be replaced with a foamed layer 60 and an adhesive layer 40 to create a synthetic leather 130. The foamed layer 60 is a foamed resin layer and can impart shock absorption and flexibility to the synthetic leather 130. The adhesive layer 40 bonds the foamed layer 60 to the base fabric 20, thereby bonding the skin layer 10 to the base fabric 20. By providing the foamed layer 60 and the substantially non-foamed adhesive layer 40 as separate layers, the contact area between the adhesive layer 40 and the base fabric 20 can be increased compared to the synthetic leather 120 described above. As a result, the synthetic leather 130 can exhibit even better abrasion resistance than the synthetic leather 120.

[0049] The foam layer 60 can be formed by a method similar to that for forming the foam adhesive layer 50 described above. After the foam layer 60 is formed, an adhesive for forming the adhesive layer 40 is applied to the surface of the foam layer 60, and then the base fabric 20 is attached to form a laminate that constitutes the synthetic leather 130. The synthetic leather 130 can be obtained by forming a surface protection layer 30 on the surface side of the skin layer 10 in the laminate.

[0050] The thickness of the foam layer 60 is not particularly limited, but is preferably 100 μm or more from the viewpoint of exhibiting good impact absorption or flexibility, and is preferably 500 μm or less from the viewpoint of cost.

[0051] The adhesive layer 40 and surface protective layer 30 in the synthetic leather 130 can be configured in the same manner as the adhesive layer 40 and surface protective layer 30 in the synthetic leather 110 described in the first embodiment, so detailed explanation will be omitted here. Preferably, the synthetic leather 130 comprises a surface layer 10 containing a vinyl chloride resin and a plasticizer, a foam layer 60 made of foamed vinyl chloride resin, and an adhesive layer 40 containing a vinyl chloride resin. It is particularly preferable that the surface layer 10, the foam layer 60, and the adhesive layer 40 each contain 90% by mass or more of vinyl chloride resin relative to 100% by mass of the resin that constitutes each of these layers. This ensures that all resin layer portions of the synthetic leather 130, excluding the surface protective layer 30, contain vinyl chloride resin, improving adhesion between adjacent layers and further improving abrasion resistance.

[0052] (Manufacturing method of synthetic leather) An example of a method for manufacturing synthetic leather 130 is described below. However, the manufacturing method described below does not limit the synthetic leather of the present invention, and the synthetic leather of the present invention may be manufactured by other manufacturing methods as appropriate within the scope of the present invention. The following describes an example in which the surface layer 10, foam layer 60, and adhesive layer 40 all contain vinyl chloride resin. First, a coating solution for forming the surface layer 10 containing a vinyl chloride resin and a polyester plasticizer is prepared, and this is applied to a release paper using a doctor knife coater, a comma doctor coater, or other conventional coating means, and then appropriately heated and dried to obtain the surface layer 10. Thereafter, a coating liquid for forming the foamed layer 60 containing a foaming agent, a vinyl chloride resin, and a polyester plasticizer is applied to the exposed surface of the obtained skin layer 10 using the same coating means as described above, and is appropriately heated to foam the coating liquid, thereby forming the foamed layer 60. Then, an adhesive containing a vinyl chloride resin is applied to the exposed surface of the obtained foam layer 60. layer The coating liquid for forming 40 is applied using the coating means described above and appropriately heated and dried to form adhesive layer 40. A fiber substrate for forming base fabric 20 is laminated onto semi-cured adhesive layer 40, and then the release paper or the like is peeled off to obtain a laminate. Thereafter, a coating liquid for forming surface protective layer 30 containing a polyurethane resin-forming composition and a crosslinking agent such as isocyanate is applied to the surface of skin layer 10 and appropriately heated to form surface protective layer 30, thereby obtaining synthetic leather 130. Note that before forming surface protective layer 30, the surface of skin layer 10 may be embossed or otherwise processed to give it a leather-like appearance.

[0053] While the present invention has been described above using the first and second embodiments, these are merely illustrative of aspects of the present invention and do not limit the present invention in any way. Furthermore, the above-described manufacturing methods do not limit the method for manufacturing the synthetic leather of the present invention. For example, synthetic leather 110 can be manufactured by omitting the step of forming foamed adhesive layer 50 and forming adhesive layer 40 after skin layer 10. Furthermore, synthetic leather 120 can be manufactured by forming foamed adhesive layer 50 in the same manner as foamed layer 60, and then laminating the fiber substrate that constitutes base fabric 20 on foamed adhesive layer 50 while it is still in a semi-cured state. [Example]

[0054] Examples of the present invention will be described below. Examples and comparative examples will be shown below using synthetic leather having a base fabric, an adhesive layer, a surface layer, and a surface protective layer as examples. However, the examples shown below do not limit the present invention in any way.

[0055] First, the materials for constituting each layer were prepared as follows: Table 1 shows the compositions and blending ratios contained in the coating liquids for forming the surface layer and the surface protection layer.

[0056] <Coating liquid for forming the surface layer> Vinyl chloride resin (ZEST PQHPN, manufactured by Shin-Daiichi Vinyl Corporation) Polyester plasticizer (adipic acid polyester plasticizer, number average molecular weight 1500, acid value 0.2KOHmg / g) Non-polyester plasticizers (phthalates Acid Stell system Plasticizer, number average molecular weight 450, acid value 0.07KOHmg / g) The ratio of polyester plasticizer to 100% by mass of total plasticizer, which is the sum of the blending amounts of polyester plasticizer and non-polyester plasticizer in the coating liquid, was calculated and shown in Table 1. The average acid value of the plasticizer in the coating liquid was calculated as the sum of the values ​​obtained by multiplying the acid value of each plasticizer by its blending ratio, and is shown in Table 1. <Coating liquid for forming foam layer> 100 parts by weight of vinyl chloride resin (ZEST PQHPN, manufactured by Shin-Daiichi Vinyl Corporation) 45 parts by weight of polyester plasticizer (adipic acid polyester plasticizer, number average molecular weight 1500, acid value 0.2 KOH mg / g) 20 parts by weight of non-polyester plasticizer (phthalate ester plasticizer, number average molecular weight 450, acid value 0.07 KOHmg / g) Foaming agent (azodicarbonamide) 1 part by mass <Coating liquid for forming adhesive layer> 100 parts by weight of vinyl chloride resin (ZEST PQHPN, manufactured by Shin-Daiichi Vinyl Corporation) 45 parts by weight of polyester plasticizer (adipic acid polyester plasticizer, number average molecular weight 1500, acid value 0.2 KOH mg / g) 20 parts by weight of non-polyester plasticizer (phthalate ester plasticizer, number average molecular weight 450, acid value 0.07 KOHmg / g) (base fabric) Fiber base material (polyester knit, organic mass = 110g / m 2 , density = well / course = 25 / 22) <Coating liquid for forming surface protective layer> Water-based polyurethane resin composition (polycarbonate-based polyurethane composition, solid content 25% by mass) Crosslinking agent (carbodiimide) Crosslinking agent (isocyanate) The blending ratios (parts by mass) of the polycarbonate-based polyurethane compositions shown in Table 1 are blending ratios by mass including the solvent.

[0057] Example 1 The coating solution for forming the surface layer, prepared according to the composition ratio shown in Table 1, was applied to release paper (manufactured by Dai Nippon Printing Co., Ltd., product name "DE-73") so that the thickness after drying would be 200 μm, and the coating was dried in an oven at 180°C for 1 minute to obtain a surface layer. Next, the adhesive layer-forming coating liquid prepared as described above was applied to the exposed side of the obtained surface layer so that the thickness after drying would be 100 μm, and the base fabric was attached, dried at 200°C for 3 minutes, and the release paper was peeled off to obtain a laminate. Then, the coating liquid for forming the surface protective layer prepared as described above was applied to the exposed surface of the surface layer of the laminate in an amount of 30 g / m 2 The mixture was dried in an oven at 120°C for 2 minutes to form a surface protective layer, thereby obtaining the synthetic leather of Example 1.

[0058] (Examples 2 to 6, Comparative Examples 1 to 3) In Examples 2 to 4 and 6 and Comparative Examples 1 to 3, synthetic leathers were produced in the same manner as in Example 1 described above, except that the composition ratios were changed to those shown in Table 1. In Example 5, a synthetic leather was produced in the same manner as in Example 1, except that a foam layer having a thickness of 300 μm was provided between the adhesive layer and the surface layer. The Examples and Comparative Examples obtained as described above were evaluated as follows. The evaluation results are shown in Table 1.

[0059] <Chemical resistance evaluation (condition 1)> The resulting synthetic leather was cut into 210 x 297 mm pieces (A4 size according to ISO 216) to prepare test specimens. Next, a glass plate was placed on a palette, and the test specimen was placed on the glass plate with the surface protective layer facing up. A white cotton cloth (Kanakin No. 3) was placed on the test specimen, and 15 ml of oleic acid was dripped onto the white cloth. Next, a glass plate was placed on top of the white cloth, and the test specimen was dried in this state at 80°C for 72 hours. After drying, the glass plate and white cloth were removed, and the surface of the test specimen was wiped with a paper towel and further dried at room temperature for 24 hours. After drying, the test specimen was cut into a φ130 mm diameter (circular shape with a diameter of 130 mm) from the center. The cut φ130 mm test specimen was placed in a DuPont impact tester and subjected to a ball drop test in accordance with JIS K 5600-5-3. The ball drop test was carried out at room temperature. The load of the ball used for the drop test was 800 g, and the ball was dropped from a distance of 15 cm. After the ball drop test, the surface of the synthetic leather (the surface protective layer side) was visually observed and evaluated based on the following evaluation criteria. <Chemical resistance evaluation (condition 2)> The test was carried out in the same manner as in the above chemical resistance evaluation (condition 1), except that the drying time in an environment at 80°C was set to 120 hours, and the evaluation was carried out based on the following evaluation criteria. [Evaluation criteria] ◯: No cracks were observed on the surface of the test piece. △: Fine cracks were observed on the surface of the test piece. ×: Cracks were observed on the surface of the test piece, and the backside fabric (base fabric) was exposed.

[0060] <Cold resistance evaluation (condition 1)> The resulting synthetic leather was cut into a φ130 mm (circular shape with a diameter of 130 mm) to prepare test specimens. The test specimens were then placed in a -30°C atmosphere and left to cool for 60 minutes. Immediately after cooling, a DuPont drop impact test based on JIS K 5600-5-3 was carried out under the same conditions as in the chemical resistance evaluation. After the ball drop test, the surface of the synthetic leather (the surface protective layer side) was visually observed and evaluated based on the following criteria. <Cold resistance evaluation (condition 2)> The test was carried out in the same manner as in the above cold resistance evaluation (condition 1), except that the test piece was placed in an atmosphere of -40°C, and the test was evaluated based on the following evaluation criteria. [Evaluation criteria] ◯: No cracks were observed on the surface of the test piece. △: Fine cracks were observed on the surface of the test piece. ×: Cracks were observed on the surface of the test piece, and the backside fabric (base fabric) was exposed.

[0061] <Wear resistance evaluation> The resulting synthetic leather was used to evaluate the abrasion resistance as follows. Specifically, a Gakushin-type friction tester specified in JIS-L-0823 (rubbing tester for color fastness testing) was used. A 30 mm wide, 250 mm long piece of JIS-L-0823 No. 6 cotton canvas was cut and clamped to the tester's sample stage to prevent wrinkles. The resulting synthetic leather was cut into 20 mm wide, 50 mm long test pieces. The test pieces were firmly attached to a friction probe with the surface protective layer facing outward. The friction probe was then rubbed against the canvas placed on the test stage at a pressure of 1,000 gf (9.8 N), a stroke of 100 mm, and a speed of 30 strokes / min. The surface condition of the test pieces was visually observed after 30,000 strokes and evaluated based on the following criteria. [Evaluation criteria] ◯: No breakage of the surface protective layer was observed. △: Slight breakage of the surface protective layer was observed. ×: The surface protective layer was severely torn.

[0062] [Table 1]

[0063] The above embodiment encompasses the following technical ideas. (1) Synthetic leather having a surface layer and a base fabric, the skin layer contains a vinyl chloride resin and a plasticizer, the plasticizer includes a polyester-based plasticizer having a number average molecular weight of 800 or more and 4000 or less, A synthetic leather characterized in that the polyester plasticizer accounts for 10% by mass or more and 80% by mass or less of the total plasticizer contained in the surface layer. (2) The synthetic leather according to (1) above, wherein the average acid value (KOH mg / g) of the plasticizer is 0.1 or more. (3) A surface protective layer is provided on the surface of the skin layer opposite to the base fabric, the surface protective layer contains a polyurethane resin and a crosslinking agent, The synthetic leather according to (1) or (2) above, wherein the crosslinking agent contains an isocyanate. (4) A foam layer or a foam adhesive layer is provided between the surface layer and the base fabric, the foam layer or the foam adhesive layer contains a vinyl chloride resin and a plasticizer, the plasticizer includes a polyester-based plasticizer having a number average molecular weight of 800 or more and 4000 or less, The synthetic leather according to any one of (1) to (3), wherein the polyester plasticizer accounts for 10% by mass or more and 80% by mass or less of the total plasticizer contained in the foam layer or the foam adhesive layer. [Explanation of symbols]

[0064] 10...epidermis layer 20...Base fabric 30...Surface protective layer 40...adhesive layer 50...Foam adhesive layer 60...Foam layer 110, 120, 130...Synthetic leather 210···Warp 220···Weft

Claims

1. A synthetic leather comprising a surface layer, a base fabric, and a surface protective layer provided on the surface of the surface layer opposite to the base fabric, the skin layer contains a vinyl chloride resin and a plasticizer, the plasticizer includes a polyester-based plasticizer having a number average molecular weight of 800 to 4,000, and the polyester-based plasticizer accounts for 10% by mass to 80% by mass of 100% by mass of the plasticizer contained in the surface layer; the average acid value (KOH mg / g) of the plasticizer contained in the surface layer is 0.1 or more, the surface protective layer contains a polyurethane resin and a crosslinking agent, the proportion of the crosslinking agent blended per 100 parts by mass of the polyurethane-based resin is 2 parts by mass or more and 20 parts by mass or less, A synthetic leather characterized in that the crosslinking agent contains an isocyanate.

2. a foam layer or a foam adhesive layer is provided between the surface layer and the base fabric, the foam layer or the foam adhesive layer contains a vinyl chloride resin and a plasticizer, 2. The synthetic leather according to claim 1, wherein the plasticizer comprises a polyester-based plasticizer having a number average molecular weight of 800 or more and 4,000 or less, and the polyester-based plasticizer accounts for 10% by mass or more and 80% by mass or less of 100% by mass of the plasticizer contained in the foamed layer or the foamed adhesive layer.

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