Coating composition and its use

Abstract

A silicone / polyurethane synthetic leather topcoat composition is disclosed. The silicone / polyurethane synthetic leather topcoat composition is a hydrosilylation curable silicone elastomer composition that provides good adhesion to polyurethane and is used to provide a topcoat for a silicone / polyurethane composite synthetic leather material. The topcoat is the cured product of the composition. Methods for making the topcoat and the silicone / polyurethane composite synthetic leather material, as well as the use of the silicone / polyurethane composite synthetic leather material, are also disclosed.

Description

Technical Field

[0001] The present disclosure relates to a silicone / polyurethane synthetic leather topcoat composition. The silicone / polyurethane synthetic leather topcoat composition is a hydrosilylation-curable silicone elastomer composition that provides good adhesion to polyurethane and is used to provide a topcoat for silicone / polyurethane composite synthetic leather materials. The topcoat is a cured product of this composition. Also disclosed are methods of making the topcoat and the silicone / polyurethane composite synthetic leather material, as well as uses of the synthetic leather material.

Background Art

[0002] A variety of synthetic alternatives to natural leather have been developed. These are used in a wide variety of applications as inexpensive alternatives. Synthetic leather is commonly used, for example, in applications such as furniture, decoration, handbags, travel bags, clothing, footwear, automotive interiors and seats.

[0003] One of the more common materials used to make synthetic leather is polyurethane (PU), which is an alternating copolymer generally prepared by reacting a di- or triisocyanate with a suitable polyol, examples of which include alkylene polyols, or polyether polyols, polyester polyols or polycarbonate polyols as shown below. Each isocyanate and polyol polymerizes through the formation of carbamate / urethane linkages as shown below.

Chemical Formula

[0004] There are a number of alternative polyurethane (PU)-based synthetic leather composite materials that include multiple layers and are used as synthetic PU leather. Perhaps one of the most common PU-based synthetic leather composite materials typically has, from bottom to top, (i) a fabric support layer, (ii) a PU sponge / adhesive layer adhered / laminated to (i), (iii) A PU "skin layer" adhered to the sponge / adhesive layer (ii), and finally (iv) A PU top coat on the skin layer, also known as the "topcoat layer" is included. In such a PU-based synthetic leather composite material, for the sake of avoiding ambiguity, it should be stated that layer (ii) is substantially sandwiched between layer (i) and layer (iii), and layer (iii) is substantially sandwiched between layer (ii) and layer (iv). "Substantially" means that although there are four separate layers, there may be mutual mixing between the layers at the interface between each layer.

[0005] The use of PU-based synthetic leather composite materials has several advantages over natural leather. In particular, it can be produced much more inexpensively and does not absorb water. It can be prepared in a variety of colors and, unlike natural leather, does not dry out over time. However, there are also several problems, including: (i) It often has an artificial appearance of imitation and a plastic smell. (ii) Unlike genuine leather, especially, it may easily develop holes or tears, so it has poor weather resistance / aging resistance over time, and (iii) Over time, it does not exhibit the same gloss or style as genuine leather. Furthermore, in order to meet increasingly stringent safety regulations and be used as synthetic leather, for example, it is necessary to meet strict physical property requirements regarding flame retardancy, soot concentration, suitable adhesive strength to prevent the coating layer from peeling off during use, heat resistance, stain resistance, solvent resistance, and hydrolysis resistance, etc. PU-based materials often cannot meet at least some of the above physical property requirements.

[0006] Another group of synthetic alternatives to natural leather is silicone-based synthetic leather materials. Such silicone-based synthetic leather materials can have several advantages over the PU-based materials discussed above. For example, silicone-based synthetic leather materials generally use a more environmentally friendly production method that does not use plasticizers, toxic heavy metals, or environmentally problematic solvents such as dimethylformamide (DMF), which often at least partially remain in the synthetic leather products after manufacturing.

[0007] Silicone-based synthetic leather composite materials can be produced via multiple routes, but generally are manufactured using a fabric support layer, layers of two or more hydrosilylation-curable liquid silicone rubber compositions, and a release liner. For example, a first liquid silicone rubber (LSR) composition may be coated onto the release liner and then cured to form a first layer or skin layer. A second LSR composition, which typically has different physical properties than the first LSR composition, is adhered to the cured first layer to form an adhesive layer, the fabric support layer is adhered to the uncured second LSR layer, and then the second LSR composition is cured to form an adhesive layer positioned between the skin layer and the fabric support layer. One or more additional layers of hydrosilylation-curable silicone elastomer compositions, which are considered suitable for forming silicone-based leather composite materials, may also be applied between the release liner and the fabric layer. For example, a third layer may be provided on the skin layer as a protective topcoat. If necessary, the release liner is removed later when needed.

[0008] Such silicone-based synthetic leather composite materials can, from a physical properties perspective, outperform conventional PU synthetic leather as they can provide, for example, better flexibility over a wide temperature range and excellent resistance to UV and heat. The topcoat is particularly important as it contributes to providing advantageous properties such as stain resistance. The topcoat is also thought to be gentle on human skin and provide an excellent feel to the user. However, such silicone-based synthetic leather composite materials are generally more expensive to prepare and may therefore not be entirely suitable for all uses.

[0009] The concept of producing silicone / polyurethane composite synthetic leather materials may be considered an alternative approach, but it has a fundamental problem that it is very difficult to adhere a layer of silicone material to a layer of polyurethane material. This is because the silicone elastomeric material and polyurethane have greatly different polarities, resulting in only weak intermolecular attractive forces, and they do not contain chemically active groups that can interact with each other. Summary of the Invention

[0010]

[0010] Therefore, the industry desires to provide a silicone / polyurethane composite synthetic leather material that can provide benefits by using one or more PU layers in combination with a silicone-based material topcoat, where the silicone-based material topcoat is provided as a replacement for a standard PU topcoat or overcoat layer and, when cured, can adhere to an adjacent PU layer (often referred to as a PU "skin" layer) in the silicone / polyurethane composite synthetic leather material.

[0011] A silicone / polyurethane synthetic leather topcoat composition, Component (i), one or more organopolysiloxane polymers having at least two unsaturated groups per molecule, the unsaturated groups being selected from alkenyl groups, alkynyl groups or mixtures thereof, and having a viscosity of 100 to 500,000 mPa·s at 25°C, Component (ii), an inorganic reinforcing filler optionally hydrophobically treated with one or more filler treating agents, such as finely divided silica, Component (iii), a polyorganosiloxane containing at least two, or at least three, silicon-bonded hydrogen (-Si-H) groups per molecule, Component (iv), a hydrosilylation catalyst, Component (v), zirconium acetylacetonate in an amount of 1 to 5% by weight of the composition, and 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione in an amount of 1 to 6% by weight of the composition, and / or a compound of the formula [Chemical formula] [wherein, R 5 is an alkyl group having 1 to 6 carbon atoms, R 6 is an alkoxy group having 1 to 6 carbon atoms, and z = 0, 1 or 2], one or more epoxy silanes or a combination thereof, and component (vi), an eco-solvent, and optionally, component (vii), a cured silicone powder to provide a silicone / polyurethane synthetic leather topcoat composition. [Advantages of the Invention]

[0012] The topcoat obtained from the curing of the above silicone / polyurethane synthetic leather topcoat composition adheres easily to polyurethane, specifically, it adheres easily to the polyurethane skin layer of the silicone / polyurethane synthetic leather, and is designed to provide a crosslinked silicone elastomeric matrix with excellent stain resistance, that is, the cured topcoat is easy to clean and has good scratch resistance.

[0013] There is also provided a silicone / polyurethane composite synthetic leather material having a topcoat in the form of a cured layer of the silicone / polyurethane synthetic leather topcoat composition described herein.

[0014] There are also provided a silicone coating formed as a reaction product of the curing of the silicone / polyurethane synthetic leather topcoat composition described herein, a topcoat using the same, a method for producing a silicone / polyurethane composite synthetic leather material, and the use of a product made from the silicone / polyurethane composite synthetic leather material. [Embodiments for Carrying Out the Invention]

[0015] (i) Organopolysiloxane polymer One or more organopolysiloxane polymers have at least two unsaturated groups per molecule, the unsaturated groups are selected from alkenyl groups, alkynyl groups or mixtures thereof, and have a viscosity of 100 to 500,000 mPa·s at 25°C, which is the component (i) of the silicone / polyurethane synthetic leather topcoat composition. The organopolysiloxane polymer (i) has the formula (I): R a SiO (4-a) / 2 (I) [Wherein, as long as it contains an essential number of unsaturated groups, each R is independently selected from an aliphatic hydrocarbyl, aromatic hydrocarbyl or organo group (any organic substituent having one free valence on a carbon atom, regardless of the type of functional group)] and has a plurality of such groups. This group may be in the pendant position (in the D or T siloxy group) or at the end (in the M siloxy group). Saturated aliphatic hydrocarbyl is not limited to alkyl groups, but is typically a monovalent saturated hydrocarbon group containing 1 to 20 carbon atoms, such as methyl, ethyl, propyl, pentyl, octyl, undecyl and octadecyl, and cycloalkyl groups such as cyclohexyl. Unsaturated aliphatic hydrocarbyl is exemplified by alkenyl groups having 2 to 10 carbon atoms, such as vinyl, allyl, butenyl, pentenyl, isopropenyl, 5-hexenyl, cyclohexenyl and hexenyl, and alkynyl groups. Aromatic hydrocarbon groups are exemplified by, but not limited to, phenyl, tolyl, xylyl, benzyl, styryl and 2-phenylethyl. Organo groups are exemplified by, but not limited to, halogenated alkyl groups such as chloromethyl and 3-chloropropyl; nitrogen-containing groups such as amino groups, amide groups, imino groups, imide groups; oxygen-containing groups such as polyoxyalkylene groups, carbonyl groups, alkoxy groups and hydroxyl groups. Further organo groups can include sulfur-containing groups, phosphorus-containing groups and / or boron-containing groups. The subscript "a" can be 0, 1, 2 or 3, but is typically mainly 2 or 3.

[0016] The siloxy group can be described by the short (abbreviated) nomenclature, namely, "M", "D", "T" and "Q" when R is an organic group, typically a methyl group (further teachings on silicone nomenclature can be found in Walter Noll, Chemistry and Technology of Silicones, dated 1962, Chapter I, pages 1-9). The M group is a siloxy group where a = 3, i.e., R3SiO 1 / 2corresponds to, and the D group is a siloxy group with a = 2, that is, R2SiO 2 / 2 corresponds to, and the T group is a siloxy group with a = 1, that is, R1SiO 3 / 2 corresponds to, and the Q group is a siloxy group with a = 0, that is, SiO 4 / 2 corresponds to.

[0017] The molecular structure of the organopolysiloxane polymer (i) is typically linear, however, there may be some branches within the molecule due to the presence of T groups (as previously described).

[0018] In the elastomer prepared by curing the silicone / polyurethane synthetic leather topcoat composition described herein, in order to achieve useful levels of physical properties, the viscosity of the organopolysiloxane polymer (i) should be at least 100 mPa·s at 25°C. The upper limit for the viscosity of the organopolysiloxane polymer (i) is limited to a maximum viscosity of 500,000 mPa·s at 25°C.

[0019] The amount (weight %) of the unsaturated groups present is determined using quantitative infrared analysis in accordance with ASTM E168. Component (i) has a viscosity of 100 mPa·s to 500,000 mPa·s at 25°C, or 200 mPa·s to 150,000 mPa·s at 25°C, or 200 mPa·s to 125,000 mPa·s at 25°C, or 200 mPa·s to 100,000 mPa·s at 25°C, or 200 mPa·s to 80,000 mPa·s measured at 25°C, using a spindle appropriate for the viscosity range based on the cup / spindle method of ASTM D1084-16 method B, unless otherwise indicated.

[0020] As long as each organopolysiloxane polymer (i) contains at least two unsaturated groups per molecule, the organopolysiloxane polymer (i) can be selected from polydimethylsiloxane, alkylmethylpolysiloxane, alkylarylpoliysiloxane, or these copolymers containing, for example, alkenyl and / or alkynyl groups, and may have any suitable end groups. For example, it may be terminated by trialkyl, alkenyldialkyl, or terminated by any other suitable combination of end groups.

[0021] Therefore, considering the presence of a high level of alkenyl and / or alkynyl groups, such as vinyl groups, trialkyl-terminated dimethylmethylvinylpolysiloxane or dialkylvinyl-terminated dimethylmethylvinylpolysiloxane copolymer may be preferred. However, as examples, the organopolysiloxane polymer (i) may be dimethylvinyl-terminated polydimethylsiloxane, dimethylvinyl-terminated dimethylmethylphenylsiloxane, trialkyl-terminated dimethylmethylvinylpolysiloxane or dialkylvinyl-terminated dimethylmethylvinylpolysiloxane copolymer.

[0022] For example, the organopolysiloxane polymer (i) containing an unsaturated group selected from alkenyl groups and / or alkynyl groups at both ends has the general formula (II): R’R’’R’’’SiO-(R’’R’’’SiO) m -SiOR’’’R’’R’ (II) It can be represented by. In formula (II), each R’ can be an alkenyl group or an alkynyl group, but typically contains 2 to 10 carbon atoms. Examples of alkenyl groups include, but are not limited to, vinyl, propenyl, butenyl, pentenyl, hexenyl, alkenylated cyclohexyl groups, heptenyl, octenyl, nonenyl, decenyl, or similar linear and branched alkenyl groups, as well as alkenylated aromatic ring structures. The alkynyl group can be selected from, but is not limited to, ethynyl, propynyl, butynyl, pentynyl, hexynyl, alkynylated cyclohexyl groups, heptynyl, octynyl, nonynyl, decynyl, or similar linear and branched alkenyl groups, as well as alkenylated aromatic ring structures.

[0023] R’’ does not contain ethylenic unsaturation, and each R’’ may be the same or different and is individually selected from a monovalent saturated hydrocarbon group typically containing 1 to 10 carbon atoms and a monovalent aromatic hydrocarbon group typically containing 6 to 12 carbon atoms. R’’ may be unsubstituted or substituted with one or more groups that do not interfere with the curing of the silicone / polyurethane synthetic leather topcoat composition described herein, such as halogen atoms. R’’’ is R’ or R’’, and m is an integer.

[0024] Component (i) of the silicone / polyurethane synthetic leather topcoat composition may include two or more organopolysiloxane polymers (i) having a viscosity of 100 to 500,000 mPa·s at 25°C. When a mixture of organopolysiloxane polymers is used for component (i), at least one of the unsaturated groups selected from alkenyl groups, alkynyl groups, or mixtures thereof, or one constitutes at least 5% by weight of the polymer per molecule, or 5 to 15% by weight of the polymer per molecule, or 6 to 15% by weight of the polymer per molecule, or 7 to 15% by weight of the polymer per molecule, and this can be determined using quantitative infrared analysis in accordance with ASTM E168.

[0025] Component (i) is typically present in an amount from 3% or 10% by weight of the composition to 50% or 45% by weight of the composition. For example, organopolysiloxane polymer (i) can be present within the range of 10 - 50% or 10 - 45% by weight of the composition.

[0026] (ii) Reinforcing filler Component (ii) of the silicone / polyurethane synthetic leather topcoat composition is a reinforcing filler such as finely divided silica. Silica and other reinforcing fillers (ii) are often treated with one or more known hydrophobizing filler treatment agents to prevent a phenomenon called "creping" or "crepe hardening" during the processing of the silicone / polyurethane synthetic leather topcoat composition.

[0027] The finely divided form of silica is preferred as the reinforcing filler (ii). Precipitated and / or fumed silica, or fumed silica, is particularly preferred due to its relatively large surface area of typically at least 50 m 2 / g (BET method according to ISO 9277:2010). Fillers having a surface area of 50 - 450 m 2 / g (BET method according to ISO 9277:2010), or 50 - 300 m 2 / g (BET method according to ISO 9277:2010) are typically used. Both types of silica are commercially available.

[0028] The amount of the reinforcing filler (ii) in the silicone / polyurethane synthetic leather topcoat composition herein, such as finely divided silica, is 5 - 40% or 5 - 30% by weight. In some examples, the amount of the reinforcing filler may be 7.5 - 30% or 10 - 30% based on the weight of the composition, or 15 - 30% based on the weight of the composition.

[0029] When the reinforcing filler (ii) is naturally hydrophilic (e.g., untreated silica filler), it is typically treated with a treating agent to make it hydrophobic. Due to the surface treatment, the filler becomes wettable by the organopolysiloxane polymer (i), so these surface-modified reinforcing fillers (ii) do not agglomerate and can be uniformly incorporated into the organopolysiloxane polymer (i). This improves the mechanical properties at room temperature of the silicone / polyurethane synthetic leather topcoat composition, and a cured material cured from the composition is obtained.

[0030] The surface treatment may be carried out before introduction into the composition or in situ (i.e., by blending these components together at room temperature or above in the presence of at least a portion of the other components of the composition herein until the filler is completely treated). Typically, the untreated reinforcing filler (ii) is treated in situ with a treating agent in the presence of the organopolysiloxane polymer (i), and after mixing, a silicone rubber-based material is obtained, to which other components may be added.

[0031] Typically, the reinforcing filler (ii) can be surface-treated with any low molecular weight organosilicon compound disclosed in the art that is applied to prevent the creping of the silicone / polyurethane synthetic leather topcoat composition during processing. For example, organosilanes, organopolysiloxanes or organosilazanes, such as hexaalkyldisilazane, short-chain siloxane diols, or fatty acids or fatty acid esters, such as stearic acid esters, which make the filler hydrophobic and thus easy to handle and result in a homogeneous mixture with other components. Specific examples include, but are not limited to, silanol-terminated trifluoropropylmethylsiloxane, dimethylsilanol-terminated vinylmethyl (ViMe) siloxane, tetramethyldi(trifluoropropyl)disilazane, tetramethyldivinyldisilazane, silanol-terminated MePh siloxane, liquid hydroxyl-terminated polydiorganosiloxane containing on average 2 to 20 repeating units of diorganosiloxane in each molecule, hexaorganodisiloxane, hexaorganodisilazane. As a processing aid, a small amount of water may be added together with the silica treatment agent.

[0032] The filler can be introduced into the silicone / polyurethane synthetic leather topcoat composition in the form of a masterbatch or base containing the filler and an organopolysiloxane polymer. The organopolysiloxane polymer used in the masterbatch or base may have a structure similar to that of component (i), or alternatively, an organopolysiloxane polymer having a viscosity within the same range as component (i) but having an alkenyl and / or alkynyl content of less than 5% by weight of the polymer. If necessary, fumed silica may be hydrophobically treated in situ during the preparation of the masterbatch by introducing a suitable hydrophobizing agent into the mixture.

[0033] The silicone / polyurethane synthetic leather topcoat composition described in this specification is cured using a hydrosilylation curing package containing an organohydrogenpolysiloxane (Component (iii)) having three or more silicon-bonded hydrogen atoms per molecule and a hydrosilylation catalyst (Component (iv)).

[0034] (iii) Organohydrogenpolysiloxane Component (iii) is a crosslinking agent in the form of a polyorganosiloxane containing at least two, or at least three silicon-bonded hydrogen (-Si-H) groups per molecule. Component (B) usually contains three or more -Si-H groups, and the hydrogen atoms can react with the unsaturated alkenyl or alkynyl groups of Component (i) to form a network structure with them, thereby curing the composition. Some or all of Component (iii) may have two -Si-H groups per molecule, especially when Component (i) has more than two (>) alkenyl or alkynyl groups per molecule.

[0035] The molecular constitution of the polyorganosiloxane (B) containing at least two or three Si-H groups per molecule is not particularly limited and may be linear, linear with some branches, cyclic, or silicone resin-based.

[0036] The silicon-bonded organic groups used in Component (iii) can be exemplified by methyl, ethyl, propyl, butenyl, pentenyl, hexyl or similar alkyl groups; phenyl, tolyl, xylyl or similar aryl groups; 3-chloropropyl, 3,3,3-trifluoropropyl or similar halogenated alkyl groups, and the preferred ones among these are methyl and phenyl groups.

[0037] Examples of the polyorganosiloxane (iii) containing at least two or three silicon-bonded hydrogen groups per molecule include, but are not limited to, the following: (a) Branched and / or chain-extended dimethylhydrogen siloxy-terminated polydimethylsiloxane, (b) Dimethylhydrogen siloxy-terminated dimethylsiloxane-methylhydrogen siloxane copolymer, (c) (CH3)2HSiO 1 / 2 units, (CH3)3SiO 1 / 2 units, and SiO 4 / 2 units, and / or silicone resin, (d) (CH3)2HSiO 1 / 2 units and SiO 4 / 2 units, and / or silicone resin, (e) (CH3)2HSiO 1 / 2 units, and SiO 4 / 2 units, and (C6H5)3SiO 1 / 2 units, and / or silicone resin, as well as alternatives where methyl is replaced by a phenyl group or other alkyl group. (f) Si-H groups, such as, for example, (CH3)2HSiO 1 / 2 groups, (CH3)2SiO 2 / 2 groups and SiO 4 / 2 groups, including or consisting of these, of silicone resin. The silicone resins mentioned above may also contain T groups and / or D groups, or may include T groups. Other possible crosslinking agents (iii) include the following: (g) 1,1,3,3-Tetramethyldisiloxane, (h) 1,3,5,7-Tetramethylcyclotetrasiloxane, (i) Tris(hydrogendimethylsiloxy)methylsilane, (j) Tris(hydrogendimethylsiloxy)phenylsilane, methylhydrogen cyclopolysiloxane, (k) Trimethylsiloxy-end-blocked methylhydrogen polysiloxane, (l) Trimethylsiloxy-end-blocked dimethylsiloxane / methylhydrogen siloxane copolymer, (m) Dimethylhydrogen siloxy terminated dimethyl polysiloxane, (n) Dimethylhydrogen siloxy terminated dimethyl siloxane / methylhydrogen siloxane copolymer, (o) Trimethylsiloxy terminated methylhydrogen siloxane / diphenyl siloxane copolymer, (p) Trimethylsiloxy terminated methylhydrogen siloxane / diphenyl siloxane / -dimethyl siloxane copolymer, (q) Trimethylsiloxy terminated methylhydrogen siloxane / methylphenyl siloxane / -dimethyl siloxane copolymer, (r) Dimethylhydrogen siloxy terminated / dimethyl siloxane / -diphenyl siloxane copolymer and / or (s) Dimethylhydrogen siloxy terminated methylhydrogen siloxane / dimethyl siloxane / -methylphenyl siloxane copolymer, (t) Alternatively, other examples include tetrakis(dimethylsiloxy)silane, hydride-terminated polyphenylmethylsiloxane, hydride-terminated polyphenyl-(dimethylhydrosiloxy)siloxane, or phenyltris(dimethylsiloxy)silane. Or, the component (ii) crosslinking agent may be a filler, for example, silica treated with one of the above.

[0038] In one alternative, the crosslinking agent may be a silicone resin containing a mixture of Q, T, D, and / or M groups having a viscosity of 10 to 5000 mPa·s at 25°C, or 10 to 1000 mPa·s at 25°C, or 10 to 500 mPa·s at 25°C, for example, (c), (d), and / or (e) described above.

[0039] The polyorganosiloxane (iii) containing at least two or three -Si-H groups per molecule is typically added in an amount such that the molar ratio of the silicon-bonded hydrogen atoms in component (iii) to those of all the unsaturated groups in the composition is 0.5:1 to 20:1, or 0.5:1 to 5:1, or 0.6:1 to 3:1. If this ratio is less than 0.5:1, a fully cured composition will not be obtained. If the ratio exceeds 20:1, the hardness of the cured composition tends to increase upon heating.

[0040] The silicon-bonded hydrogen (Si-H) content of component (iii) is determined using quantitative infrared analysis in accordance with ASTM E168. In this example, the ratio of silicon-bonded hydrogen to alkenyl (vinyl) and / or alkynyl is important when relying on the hydrosilylation curing process. Generally, this ratio is determined by calculating the total weight percentage [V] of alkenyl groups, such as vinyl, in the composition and the total weight percentage [H] of silicon-bonded hydrogen in the composition. Assuming the molecular weight of hydrogen is 1 and the molecular weight of vinyl is 27, the molar ratio of silicon-bonded hydrogen to vinyl is 27[H] / [V].

[0041] The molecular weight of this component is not specifically limited, but the viscosity is typically 15 to 50,000 mPa·s at 25°C, adapting the viscosity according to the viscosity of the polymer using either a Brookfield DV 3T Rheometer or a Brookfield® rotational viscometer with a spindle LV-4 (designed for viscosities in the range of 1,000 to 2,000,000 mPa·s) or, for viscosities less than 1000 mPa·s, a Brookfield® rotational viscometer with a spindle LV-1 (designed for viscosities in the range of 15 to 20,000 mPa·s).

[0042] Component (iii) of the silicone / polyurethane synthetic leather topcoat composition is a polyorganosiloxane containing at least two or at least three silicon-bonded hydrogen (-Si-H) groups per molecule, which, under the catalytic activity of component (iv) mentioned below, functions as a crosslinking agent for polymer (i) by an addition reaction between the silicon-bonded hydrogen atoms in component (iii) and the alkenyl group and / or alkynyl group in component (i). Component (iii) contains at least 5,000 parts per million (ppm) of silicon-bonded hydrogen (Si-H), or at least 7,000 ppm, or 7,000 - 12,000 ppm of silicon-bonded hydrogen, or 8,000 ppm - 11,000 ppm of silicon-bonded hydrogen. As a result, the silicon-bonded hydrogen atoms of this component can react sufficiently with the alkenyl group and / or alkynyl group of component (i), typically the alkenyl group, especially the vinyl group, to form a network structure with them, thereby curing the composition. The quantity of silicon-bonded hydrogen present is also determined using quantitative infrared analysis in accordance with ASTM E168.

[0043] Component (iii) is typically present in the total composition in an amount of 5 - 30% by weight, 5 - 20% by weight, or 10 - 20% by weight of the composition. However, the amount present is typically determined by the molar ratio between the silicon-bonded hydrogen atoms in component (iii) and the total number of all unsaturated groups, such as alkenyl and alkynyl groups, often vinyl groups, as described above.

[0044] iv) Hydrosilylation catalyst The silicone / polyurethane synthetic leather topcoat composition cures via a hydrosilylation (addition) reaction catalyzed by a hydrosilylation (addition curing) catalyst (iv), which is a metal selected from the platinum metal group, namely platinum, ruthenium, osmium, rhodium, iridium, and palladium, or compounds of such metals. These catalysts are preferred due to the high activity levels of platinum and rhodium compounds for the hydrosilylation reaction.

[0045] The catalyst (iv) can be a platinum group metal, a platinum group metal adhered to a carrier such as activated carbon, a metal oxide such as aluminum oxide or silicon dioxide, silica gel or powdered charcoal, or a compound or complex of a platinum group metal.

[0046] Examples of preferred hydrosilylation catalysts (iv) are platinum-based catalysts such as platinum black, platinum oxide (Adams' catalyst), platinum on various solid supports, chloroplatinic acid, an alcoholic solution of chloroplatinic acid, and a complex of chloroplatinic acid with an ethylenically unsaturated compound such as an olefin and an organosiloxane containing an ethylenically unsaturated silicon-bonded hydrocarbon group. Soluble platinum compounds that can be used include, for example, platinum-olefin complexes of the formula (PtCl2·(olefin)2 and H(PtCl3·olefin), and in this context, the use of alkenes having 2 to 8 carbon atoms such as ethylene, propylene, butene and octene isomers, or cycloalkanes having 5 to 7 carbon atoms such as cyclopentene, cyclohexene and cycloheptene is preferred. Other soluble platinum catalysts include, as examples, a platinum-cyclopropane complex of the formula (PtCl2C3H6)2, a reaction product of hexachloroplatinic acid with an alcohol, an ether and an aldehyde or a mixture thereof, or a reaction product of hexachloroplatinic acid with methylvinylcyclotetrasiloxane in the presence of sodium bicarbonate in an ethanol solution. Platinum catalysts having phosphorus, sulfur and amine ligands such as (Ph3P)2PtCl2; and complexes of platinum with vinylsiloxanes such as sym-divinyltetramethyldisiloxane can also be used.

[0047] Therefore, specific examples of suitable platinum-based catalysts include the following: (i) A complex of chloroplatinic acid with an organosiloxane containing an ethylenically unsaturated hydrocarbon group is described in U.S. Patent No. 3,419,593. (ii) Chloroplatinic acid in either the hexahydrate form or the anhydrous form. (iii) A platinum-containing catalyst obtained by a method comprising reacting chloroplatinic acid with an aliphatic unsaturated organosilicon compound, such as divinyltetramethyldisiloxane, (iv) An alkene-platinum-silyl complex described in U.S. Patent No. 6,605,734, such as (COD)Pt(SiMeCl2)2 [where "COD" is 1,5-cyclooctadiene], and / or (v) Karstedt catalysts, typically a platinum divinyltetramethyldisiloxane complex containing about 1% by weight of platinum in a solvent such as toluene, can be used. These are described in U.S. Patent Nos. 3,715,334 and 3,814,730.

[0048] The hydrosilylation catalyst (iv) of the silicone / polyurethane synthetic leather topcoat composition is present in the entire composition in a catalytic amount, that is, in an amount or quantity sufficient to catalyze the addition / hydrosilylation reaction under the desired conditions and cure the composition into an elastomeric material. Various levels of the hydrosilylation catalyst (iv) can be used to regulate the reaction rate and the kinetics of curing. The catalytic amount of the hydrosilylation catalyst (iv) generally refers to a platinum group metal in parts per million (ppm), between 0.01 ppm and 10,000 ppm, or between 0.01 ppm and 5000 ppm, or between 0.01 ppm and 3,000 ppm, or between 0.01 ppm and 1,000 ppm, based on the weight of the composition. In a specific embodiment, the catalytic amount of this catalyst can be a metal within the range of 0.01 to 1,000 ppm, or 0.01 to 750 ppm, or 0.01 to 500 ppm, or 0.01 to 100 ppm, based on the weight of the composition. These ranges may relate solely to the metal content within the catalyst or to the entire specified catalyst (including ligands), but typically these ranges relate solely to the metal content within the catalyst. The catalyst may be added as a single species or as a mixture of two or more different species. Typically, depending on the form / concentration in which the catalyst package is provided, the amount of catalyst present is within the range of 0.001 to 3.0 wt% of the composition, or 0.1 to 3.0 wt% of the composition, or 0.1 to 2.0 wt% of the composition, or 0.1 to 1.5 wt% of the composition.

[0049] Component (v) Adhesion promoter Component (v) is an adhesion promoter for adhering the silicone / polyurethane synthetic leather topcoat composition to an adjacent polyurethane layer of the silicone / polyurethane synthetic leather, such as a polyurethane skin layer, and is composed of zirconium acetylacetonate in an amount of 1 to 5 wt% of the composition, and 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione of the following structure in an amount of 1 to 6 wt% of the composition

Chemical formula

[0050] While not bound by current theory, such adhesion promoters are thought to react with the hydroxyl groups of the adjacent polyurethane layer on which the silicone / polyurethane synthetic leather topcoat composition is applied by accelerating the hydrolysis and condensation of the silane.

[0051] Component (vi) - eco-solvent Component (vi) of the silicone / polyurethane synthetic leather topcoat composition is an eco-solvent. Any suitable eco-solvent can be used. Examples include isopentadecane, isohexadecane, isoheptadecane, isooctadecane, isononadecane, and mixtures thereof, or trimethyl-terminated polydimethylsiloxane having a viscosity of 5 mPa·s or more (≧) at 25°C to 100 mPa·s or less (≦) at 25°C. It is noted that the use of trimethyl-terminated polydimethylsiloxane having a viscosity of less than 5 mPa·s at 25°C actually seems to result in a leather material where stretch marks turn white. In one embodiment, the eco-solvent comprises or consists of isohexadecane. The eco-solvent is present in the composition as a means for diluting the composition and is present in the composition in an amount of 30 to 70% by weight of the composition. Optionally or necessarily, the eco-solvent can be present in either or both parts of Part A and Part B.

[0052] Component (vii) Optional cured silicone elastomer powder If necessary, any suitable cured silicone elastomer powder may be used in the silicone / polyurethane synthetic leather topcoat composition. In one alternative, the cured silicone elastomer powder (vii) has an average particle size of 0.01 to 100 μm, or 0.01 to 50 μm, or 0.01 to 25 μm. These may contain chemical functional groups, such as epoxy groups, (meth)acryloxy groups, or may be coated, for example, with a silica treatment coating.

[0053] The cured silicone elastomer powder is made from a suitable curable silicone composition. Examples of curable silicone compositions include addition (hydrosilylation) reaction-curable silicone compositions, condensation reaction-curable silicone compositions, organoperoxide-curable silicone compositions, and ultraviolet-curable silicone compositions. Addition reaction-curable and condensation reaction-curable silicone compositions are preferred because they are easy to handle.

[0054] Silicone elastomer powder is generally prepared by making a homogeneous aqueous emulsion of a curable silicone composition, first by dispersing the curable silicone composition in water or an aqueous surfactant solution, and then subjecting this dispersion to the action of a mixing device such as a stirrer, for example, a homogenizer, a colloid mill or an ultrasonic oscillator. The aqueous curable silicone emulsion is preferably prepared using a surfactant in order to obtain a very stable emulsion in which the curable silicone composition has a small average particle diameter. Then, by curing the curable silicone present in the aqueous emulsion, an aqueous dispersion of the cured silicone powder is produced. This curing can be affected by leaving the aqueous emulsion at room temperature or by heating the aqueous emulsion. When heating the aqueous curable silicone emulsion, the preferred heating temperature should be 100 °C or less, and the particularly preferred temperature is in the range of 40 °C to 95 °C. Techniques for heating the aqueous curable silicone emulsion are by directly heating the aqueous emulsion or by adding the aqueous emulsion to hot water. Examples of commercially available products that can be used as component (vii) include, by way of example, Dowsil™ 23N, Dowsil™ 603T additive and Dowsil™ 9701 Cosmetic Powder manufactured by Dow Silicones Corporation.

[0055] The cured silicone rubber powder is present in the silicone / polyurethane synthetic leather topcoat composition, i.e., at the time when part A and part B are mixed together, in an amount of 2.5 to 20% by weight of the composition, or 2.5 to 15% by weight of the composition, or 2.5 to 10% by weight of the composition.

[0056] Optional additive The silicone / polyurethane synthetic leather topcoat composition may contain one or more additives. Examples of these optional additives include curing inhibitors, inorganic non-reinforcing fillers, electrically conductive additives, pot life extenders, lubricants, flame retardants, pigments, colorants, chain extenders, heat stabilizers, compression set improvement additives, anti-squeal agents, antioxidants, antistatic agents, antifouling agents and light stabilizers, anti-freezing agents, and / or biocides, and mixtures thereof.

[0057] Inhibitor Since a hydrosilylation curing system is utilized, optionally, a suitable inhibitor for retarding or preventing the activity of the catalyst may be incorporated into the composition to obtain a longer working time or pot life for the silicone / polyurethane synthetic leather topcoat composition.

[0058] Inhibitors for platinum metal-based catalysts, generally platinum metal-based catalysts are well-known in the art. Hydrosilylation or addition reaction inhibitors include hydrazine, triazole, phosphine, mercaptan, organic nitrogen compounds, acetylenic alcohols, silylated acetylenic alcohols, such as methyl(tris(1,1-dimethyl-2-propynyloxy))silane, maleate, fumarate, ethylenic or aromatic unsaturated amides, ethylenic unsaturated isocyanates, olefinic siloxanes, unsaturated hydrocarbon monoesters and diesters, conjugated en-ynes, hydroperoxides, nitriles and diaziridines. Alkenyl-substituted siloxanes described in U.S. Patent No. 3,989,667 may be used, among which cyclic methylvinylsiloxane is preferred.

[0059] Another class of known inhibitors for platinum catalysts includes the acetylenic compounds disclosed in U.S. Patent No. 3,445,420. Acetylenic alcohols, such as 2-methyl-3-butyn-2-ol, constitute a preferred class of inhibitors that arrest the activity of platinum-containing catalysts at 25°C. Hydrosilylation-curable silicone elastomer compositions containing these inhibitors typically need to be heated at temperatures above 70°C in order to cure at a practical rate.

[0060] Examples of acetylenic alcohols and their derivatives include 1-ethynyl-1-cyclohexanol (ETCH), 2-methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-butyn-2-ol, propargyl alcohol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclopentanol, 1-phenyl-2-propynol, 3-methyl-1-penten-4-yn-3-ol, and mixtures thereof.

[0061] When present, low inhibitor concentrations of 1 mole of inhibitor per mole of the metal of catalyst (iv) impart satisfactory storage stability and cure rates in some examples. In other examples, inhibitor concentrations of up to 500 moles of inhibitor per mole of the metal of catalyst (iv) are required. The optimal concentration of a given inhibitor in a given composition is readily determined by routine experimentation. Depending on the concentration and form in which the selected inhibitor is available / commercially obtainable, the inhibitor, when present in the composition, is typically present in an amount of 0.0125 to 10 wt% of the composition. The above mixtures may also be used.

[0062] Inorganic non-reinforcing fillers Inorganic non-reinforcing fillers in the silicone / polyurethane synthetic leather topcoat composition, when present, can include crushed quartz, diatomaceous earth, barium sulfate, iron oxide, titanium dioxide, and carbon black, wollastonite, and platelet-type fillers such as graphite, graphene, talc, mica, clay, layered silicate, kaolin, montmorillonite, and mixtures thereof. Other inorganic non-reinforcing fillers that can be used alone or in addition to the above include aluminite, calcium sulfate (anhydrite), gypsum, calcium sulfate, magnesium carbonate, aluminum trihydroxide, magnesium hydroxide (brucite), graphite, copper carbonate such as malachite, nickel carbonate such as zarachite, barium carbonate such as witherite, and / or strontium carbonate such as strontianite.

[0063] Inorganic non-reinforcing fillers, when present, can alternatively or additionally be selected from silicates from the group consisting of aluminum oxide, cordierite group, garnet group, aluminosilicate, cyclic silicate, chain silicate, and layered silicate. The cordierite group includes, but is not limited to, silicate minerals such as forsterite and Mg2SiO4. The garnet group includes, but is not limited to, pulverized silicate minerals such as pyrope, Mg3Al2Si3O 12 、 grossular and Ca2Al2Si3O 12 and the like. Aluminosilicates include, but are not limited to, pulverized silicate minerals such as sillimanite, Al2SiO5, mullite, 3Al2O3·2SiO2, kyanite, and Al2SiO5. The cyclic silicate group includes, but is not limited to, silicate minerals such as cordierite and Al3(Mg,Fe)2[Si4AlO 18 and the like. The chain silicate group includes, but is not limited to, pulverized silicate minerals such as wollastonite and Ca[SiO3].

[0064] Suitable layered silicates, such as available silicate minerals, include, but are not limited to, mica, K2Al 14 [Si6Al2O20 (OH)4, pyrophyllite, Al4[Si8O 20 (OH)4, talc, Mg6[Si8O 20 (OH)4, serpentine, such as asbestos, kaolinite, Al4[Si4O 10 (OH)8 and vermiculite. When present, the non-reinforcing filler is present in the composition up to a maximum of 1 to 50% by weight in total.

[0065] If considered necessary at any time, the non-reinforcing filler may also be treated to be hydrophobic as described above for the reinforcing filler (ii), which makes handling easier and results in a homogeneous mixture with other components. Similar to the case of the reinforcing filler (ii), surface treatment enables the non-reinforcing filler to be wetted more easily by the organopolysiloxane polymer (i), improving the properties of the silicone / polyurethane synthetic leather topcoat composition, such as better processability (e.g., lower viscosity, better release ability and / or lower adhesion to processing equipment, such as a two-roll mill), heat resistance, and mechanical properties.

[0066] Any suitable antioxidant, antistatic agent, antifouling agent and / or light stabilizer may be utilized in the composition.

[0067] Preferably, the electrically conductive additive that can be used herein is an inorganic substance. Examples of electrically conductive additives that may be present in the silicone / polyurethane synthetic leather topcoat composition include metal particles, metal oxide particles, metal-coated metallic particles (e.g., silver-plated nickel), metal-coated non-metallic core particles (e.g., silver-coated talc or mica or quartz), and combinations thereof. The metal particles can be in the form of powders, flakes or filaments, and mixtures or derivatives thereof.

[0068] A pot life extender, such as triazole, may be used, but is not considered necessary within the scope of the present invention. Thus, the silicone / polyurethane synthetic leather topcoat composition may be free of a pot life extender.

[0069] In the case of a lubricant, the lubricant may be reactive or non-reactive with other elements of the composition. Examples of lubricants include organopolysiloxanes having a basic structure similar to the basic structure of component (i), but having only one unsaturated group per molecule, for example, one alkenyl group. Alternatively, the lubricant may be an organic wax or the like. When the wax is reactive, for example, it may be an alkenylated wax having 15 to 30 carbons per molecule, or having 15 to 30 carbons per molecule and at least one alkenylated group per molecule, for example, a vinyl group.

[0070] Non-reactive lubricants may be present in the composition if desired, and examples of these include, but are not limited to, boron nitride, graphite, molybdenum sulfide, etc., or mixtures thereof.

[0071] Examples of flame retardants include aluminum trihydrate, magnesium hydroxide, calcium carbonate, zinc borate, wollastonite, mica, and chlorinated paraffin, hexabromocyclododecane, triphenyl phosphate, dimethyl methylphosphonate, tris(2,3-dibromopropyl) phosphate (brominated tris), and mixtures or derivatives thereof.

[0072] Examples of pigments include carbon black, iron oxide, titanium dioxide, chromium oxide, bismuth vanadate, and mixtures or derivatives thereof.

[0073] Examples of colorants include vat dyes, reactive dyes, acid dyes, chrome dyes, disperse dyes, cationic dyes, and mixtures thereof.

[0074] Optional additives may be used, for example, as non-reinforcing fillers and flame retardants, for more than one reason, and if present, they can function in both roles. When present, or if so, the aforementioned additional components are present in an amount of 0.1 to 30% by weight, or 0.1 to 20% by weight of the composition, in total.

[0075] To prevent premature curing during storage, the silicone / polyurethane synthetic leather topcoat composition is stored in two parts, Part A and Part B, until use. Typically, Part A contains an organopolysiloxane polymer (i) and a portion of the reinforcing filler (ii), and a hydrosilylation catalyst (iv), and Part B contains the remaining organopolysiloxane polymer (i) and reinforcing filler (ii), together with an organohydrogenpolysiloxane (iii) and, usually, an inhibitor if present, although the inclusion of the inhibitor can vary depending on the choice of inhibitor used. The two-part composition can be designed to be mixed together in any suitable ratio depending on the amounts of the organopolysiloxane polymer (i) and reinforcing filler (ii) in Part B, and thus can be mixed at a weight ratio of Part A:Part B of 15:1 to 1:2, but preferably at a weight ratio of Part A:Part B of 2:1 to 1:2, or 1.5:1 to 1:1.5, or 1:1.

[0076] Optional additives can be introduced into the silicone / polyurethane synthetic leather topcoat composition, if desired, in either Part A or Part B, provided they do not adversely affect any of the other components in each part.

[0077] The individual parts of the silicone / polyurethane synthetic leather topcoat composition may be prepared by any suitable method. For this purpose, any mixing techniques and apparatus described in the prior art can be used. The particular apparatus to be used is determined according to the components and the viscosity of the final curable silicone / polyurethane synthetic leather topcoat composition. Suitable mixers include, but are not limited to, paddle type mixers such as planetary mixers and kneading type mixers. Cooling of the components during mixing may also be desirable to avoid premature curing of the composition.

[0078] As discussed previously, the component (ii) reinforcing filler can be introduced into the silicone / polyurethane synthetic leather topcoat composition in the form of a filler (e.g., fumed silica) masterbatch. The masterbatch is used, for example, to introduce fumed silica into both part A and part B of the composition. Such a masterbatch can include 25 to 45 wt% fumed silica and 55 to 75 wt% organopolysiloxane containing at least two alkenyl and / or alkynyl groups per molecule. The organopolysiloxane can be an organopolysiloxane having the same viscosity range as component (i) above and / or component (i), but with an alternative alkenyl and / or alkynyl content. In one embodiment, the organopolysiloxane containing at least two alkenyl and / or alkynyl groups per molecule in the fumed silica masterbatch is a dimethylvinyl terminated polydimethylsiloxane having a viscosity between 30,000 mPa·s and 80,000 mPa·s at 25°C and a vinyl content of the polymer of 0.05 to 0.2 wt% or 0.05 to 0.15 wt% of the polymer, determined using quantitative infrared analysis according to ASTM E168. Such a masterbatch may contain only fumed silica and the polymer, but optionally may also contain small amounts of other components, such as hexamethyldisilazane (HMDZ), divinyltetramethyldisiloxane, dimethylhydroxy terminated methylvinylsiloxane polymer (having a viscosity of 10 to 100 mPa·s and a vinyl content of the polymer of 5 to 20 wt% or 7.5 to 15 wt% of the polymer, determined using quantitative infrared analysis according to ASTM E168); and / or water.

[0079] Thus, when part A and part B are mixed together, the silicone / polyurethane synthetic leather topcoat composition may include the following. Component (i), one or more organopolysiloxane polymers having a viscosity of 100 mPa·s to 500,000 mPa·s at 25°C, or 200 mPa·s to 150,000 mPa·s at 25°C, or 200 mPa·s to 125,000 mPa·s at 25°C, or 200 mPa·s to 100,000 mPa·s at 25°C, or 200 mPa·s to 80,000 mPa·s as measured at 25°C, in an amount of 3% by weight or 10% by weight to 50% by weight or 45% by weight of the composition, and having at least two unsaturated groups per molecule. For example, the organopolysiloxane polymer (i) may be present in the range of 10 to 50% by weight or 10 to 45% by weight of the composition. Component (ii), a reinforcing filler which may be introduced directly into the composition or in the form of a masterbatch, i.e., preferably hydrophobically treated fumed silica; the BET surface area is generally at least 50 m 2 / g (BET method according to ISO 9277:2010). The filler has a surface area of 50 to 450 m 2 / g (BET method according to ISO 9277:2010) or 50 to 300 m 2 / g, and the amount of the reinforcing filler (ii), such as finely divided silica, in the hydrosilylation-curable silicone elastomer composition herein is 5 to 40% by weight, or 5 to 30% by weight. In some examples, the amount of the reinforcing filler may be 7.5 to 30% by weight, or 10 to 30% by weight, or 15 to 30% by weight of the composition. In the case of a masterbatch, the masterbatch may include 25 to 45% by weight of fumed silica, 55 to 75% by weight of component (i), and / or dimethylvinyl-terminated polydimethylsiloxane having a viscosity between 50,000 mPa·s and 80,000 mPa·s at 25°C and a vinyl content of 0.05 to 0.2% by weight of the polymer, or a vinyl content of 0.05 to 0.15% by weight of the polymer, or 55 to 75% by weight of the dimethylvinyl-terminated polydimethylsiloxane described above. The masterbatch composition may also initially include a treatment agent for hydrophobizing the filler in situ, thereby facilitating mixing with the polymer. Component (iii), a polyorganosiloxane containing at least two or at least three silicon-bonded hydrogen (-Si-H) groups, is present in the total composition in an amount of 5 to 30% by weight, 5 to 20% by weight, or 10 to 20% by weight of the composition. However, the amount present is typically determined by the molar ratio of the silicon-bonded hydrogen atoms in component (iii) to the total number of all unsaturated groups, and is 0.5:1 to 20:1, or 0.5:1 to 10:1, or 0.5:1 to 5:1, or 1:1 to 5:1, and preferably Si-H is in excess. The viscosity of component (iii) is 15 to 50 mPa·s at 25°C, or 15 to 40 mPa·s at 25°C, or 20 to 35 mPa·s at 25°C. Component (iv), a hydrosilylation catalyst composition provided in a catalytic amount, is present in the range of 0.01 to 3.0% by weight of the composition, or 0.1 to 3.0% by weight of the composition, or 0.1 to 2.0% by weight of the composition, or 0.1 to 1.5% by weight of the composition, and contains a platinum-based metal in parts per million (ppm) in the range of 0.01 ppm to 10,000 ppm, or 0.01 ppm to 7500 ppm, or 0.01 ppm to 3,000 ppm, or 100 ppm to 6,000 ppm based on the combined weight of components (i) and (ii). Component (v), zirconium acetylacetonate in an amount of 1 to 5% by weight of the composition, and 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione in an amount of 1 to 6% by weight of the composition, and / or one or more epoxy silanes of the formula

Chemical formula

[0080] The total weight percentage of the composition containing components (i) to (vii) and any additives is 100% by weight, but may be any suitable combination as described above.

[0081] In the hydrosilylation-curable silicone elastomer composition of the silicone / polyurethane synthetic leather topcoat composition, the order of mixing the components is not critical. Suitable parts A and B are prepared, and then parts A and B are mixed together immediately before use at a predetermined weight ratio between 15:1 and 1:2, for example, at a ratio of 1:1 as an example.

[0082] The curing of the silicone / polyurethane synthetic leather topcoat composition can be carried out at a temperature suitable for hydrosilylation curing. For example, a curing temperature of about 80°C to 180°C, or 80°C to 150°C, or 120°C to 150°C. It is essential that the curing temperature of the described silicone / polyurethane synthetic leather topcoat composition does not adversely affect other layers of the silicone / polyurethane composite synthetic leather material.

[0083] The described silicone / polyurethane synthetic leather topcoat composition is used as a topcoat for the silicone / polyurethane composite synthetic leather material. This is because once cured, it provides significant adhesion to the adjacent polyurethane layer, has excellent stain resistance, i.e., is easy to clean and exhibits good scratch resistance as shown in the following examples. The silicone / polyurethane synthetic leather topcoat composition may also be applied to various other types of leather, such as conventional leather, nubuck or suede, but is specifically designed for use with polyurethane.

[0084] The silicone / polyurethane synthetic leather topcoat composition can be provided by a combination of the methods discussed below. For example, in the final step of the preparation process, it can be coated onto a suitable polyurethane-based composite material to produce the silicone / polyurethane composite synthetic leather material. In such a case, the silicone / polyurethane composite synthetic leather material can be of any suitable combination of suitable layers, and once the silicone / polyurethane synthetic leather topcoat composition is applied and cured, it forms a silicone topcoat adhered onto the layer.

[0085] A suitable polyurethane (PU) refers to an alternating copolymer that is generally prepared by reacting a di- or triisocyanate with a suitable polyol, examples of which include alkylene polyols, polyether polyols, polyester polyols, or polycarbonate polyols. Each isocyanate and polyol polymerizes through the formation of carbamate / urethane bonds. These do not contain polyureas or mixtures with polyureas.

[0086] The silicone / polyurethane composite synthetic leather material may include a plurality of, for example, 2, 3, or 4 different composite layers together with the cured product of the silicone / polyurethane synthetic leather topcoat composition that functions as a topcoat. Thus, for example, the silicone / polyurethane composite synthetic leather material, from bottom to top, (a) A cloth support layer; (b) A sponge / adhesive layer adhered to (a); The sponge layer can typically be made of polyurethane, but optionally, any other suitable sponge or adhesive material may be utilized. (c) A suitable polyurethane "skin layer" adhered to the sponge / adhesive layer (b); and finally (d) The cured product of the silicone / polyurethane synthetic leather topcoat composition provided as a topcoat on top of the suitable polyurethane skin layer. may be included. Here, layer (b) is substantially sandwiched between layer (a) and (c), and layer (c) is substantially sandwiched between layer (b) and (d).

[0087] To avoid doubt, layer (b) is substantially sandwiched between layer (a) and (c), and layer (c) is substantially sandwiched between layer (b) and the cured product (d) of the silicone / polyurethane synthetic leather topcoat composition. "Substantially" means that although there are four separate layers, there may be some intermixing between the layers at the interface between each layer.

[0088] The fabric support layer can be made from any suitable fabric material, such as a woven, knitted or non-woven fabric made from synthetic resin fibers, natural fibers and / or microfibers. Examples of fabric materials include, but are not limited to, polyester fibers, viscose rayon fibers, polyamide fibers, nylon, acrylic fibers, polyolefin fibers; cellulose fibers such as cotton; and elastic fabric materials such as spandex, and may be used as a mixture of any two or more of the above. The fabric support layer is designed to enhance the mechanical strength of the silicone / polyurethane composite synthetic leather material.

[0089] Furthermore, any suitable sponge layer / adhesive layer may be utilized as component (b) in the above, but typically the sponge layer / adhesive layer is made at least in part from a polyurethane material. The sponge layer / adhesive layer may have any desired dry film thickness, for example, 50 μm to 1 mm thick, or 150 μm to 1 mm, or 250 μm to 1 mm thick, or 300 μm to 1 mm thick. Typically, after application, it is dried at any suitable temperature, for example, 125 to 180 °C, or 125 to 170 °C, or 130 to 160 °C, for a suitable period of up to 20 minutes, or 1 to 10 minutes, or 1.5 minutes to 10 minutes, or 2 minutes to 10 minutes. However, the preferred method of adhering the sponge layer / adhesive layer to the fabric support layer is by lamination. Typically, such a lamination step may occur as part of the above drying process, and the lamination starts when the sponge layer / adhesive layer is partially dry or when it is wetted before starting the drying step, with the former being preferred.

[0090] Similarly, any suitable polyurethane skin layer may be utilized. The polyurethane skin layer is designed as a protective synthetic layer. The polyurethane skin layer may have any suitable dry film thickness, for example, 25 μm to 500 μm thick, or 25 μm to 300 μm, or 25 to 250 μm, or 50 to 200 μm thick. The polyurethane skin layer can be dried at any suitable temperature, for example, 50 - 175 °C, or 75 - 175 °C, or 75 - 150 °C, or 75 - 140 °C, for a period of 30 seconds to 5 minutes, or 30 seconds to 4 minutes, or 1 minute to 4 minutes, or 1 minute to 3 minutes.

[0091] Prior to the application of the silicone / polyurethane synthetic leather topcoat composition, the PU skin layer may be activated, if desired, using a suitable activation method, for example, by plasma treatment, corona discharge treatment, UV-C / ozone or vacuum-UV irradiation.

[0092] Therefore, the silicone / polyurethane composite synthetic leather material can be prepared by preparing a fabric support as the fabric support layer, applying a suitable polyurethane layer on the fabric support layer, drying the polyurethane layer, and then applying the silicone / polyurethane synthetic leather topcoat composition described herein on the polyurethane layer.

[0093] Alternatively, the silicone / polyurethane composite synthetic leather material may be prepared as follows: Obtaining a fabric support layer (a), applying a sponge layer (b) on the fabric support layer (a), curing / drying / layering the sponge layer (b) if necessary, applying a polyurethane skin layer (c) on the surface of the sponge layer (b) away from the fabric support (a), drying the skin layer (c), applying the silicone / polyurethane synthetic leather topcoat composition described herein on the surface of the polyurethane skin layer, and curing the silicone / polyurethane synthetic leather topcoat composition.

[0094] Alternatively, the above process may be carried out in reverse, using a release liner as a temporary support until use. In this example, the process may be continuous or in two parts. In a two-part process, the polyurethane skin layer (c) is applied onto the release liner using any suitable means and then dried, the sponge / adhesive layer (b) is applied onto the skin layer (c), and before the sponge / adhesive layer (b) is dried or after it is partially dried, the fabric support layer (a) is applied by starting the lamination onto the face of the sponge layer (b) remote from the skin layer (c). In such a case, the partially prepared silicone / polyurethane composite synthetic leather material can be stored and then separately treated with a silicone / polyurethane synthetic leather topcoat composition. In such a case, the release liner may be removed and, if desired, the dried polyurethane skin layer may be activated, for example, by corona discharge, etc., and the silicone / polyurethane synthetic leather topcoat composition (d) is applied onto the dried skin layer (c) and cured.

[0095] In an alternative continuous process, it is a repetition of the above process except that the silicone / polyurethane synthetic leather topcoat composition (d) is applied directly onto the release liner and cured, and then the skin layer (c) is applied onto the cured silicone / polyurethane synthetic leather topcoat composition (d), and then the process is continued as shown above.

[0096] The release liner is provided to protect the outer surface of the silicone / polyurethane composite synthetic leather material after the silicone / polyurethane synthetic leather topcoat composition is applied and cured, or to protect the skin layer in the case of a two-part process until it is desired to apply the silicone / polyurethane synthetic leather topcoat composition.

[0097] Regardless of the method used above, a silicone / polyurethane synthetic leather topcoat composition is applied and cured so as to obtain a dry film thickness of about 2 to 50 μm, or 5 to 30 μm, or 10 to 30 μm. This composition can be cured at any suitable temperature, for example, about 80°C to 180°C, or 80°C to 160°C, or 80°C to 130°C, for a suitable period, for example, 30 seconds to 15 minutes, or 30 seconds to 7.5 minutes, or 30 seconds to 5 minutes, or 1 to 2.5 minutes. It is important that the curing temperature of the silicone / polyurethane synthetic leather topcoat composition described herein does not adversely affect the other layers of the silicone / polyurethane composite synthetic leather material.

[0098] Optionally, the silicone / polyurethane composite synthetic leather material may be post-cured at a temperature between about 75°C and 180°C, generally, although not necessarily, towards the lower end of the range, for example, at 75 to 120°C for 2 to 48 hours, or 6 to 36 hours, or 10 to 24 hours.

[0099] Each of the upper layers (b), (c) and (d) can be applied using any suitable coating method, for example, spraying, rolling, brushing, spin coating, dip coating, solvent casting, slot die coating, spray coating, knife coating or gravure coating.

[0100] Any suitable release liner may be used, for example, the super-matte release paper ARX175DM manufactured by Japan Asahi. Any suitable release liner, for example, the super-matte release paper ARX175DM manufactured by Japan Asahi, the release papers DE-7, DE-90, DE-43C, DE-73J manufactured by Dai Nippon Printing Co., Ltd. in Japan, or also the semi-matte release paper DE-73M manufactured by Dai Nippon Printing Co., Ltd. in Japan may be used. Each curing step may be carried out by curing and drying in a suitable furnace, for example, a hot air furnace, and in the case of a continuous process, it may be carried out in a conveyor furnace.

[0101] The above process shows the preparation of an example of a silicone / polyurethane composite synthetic leather material. The reader can understand that if necessary, additional layers can be introduced into the material as desired.

[0102] The silicone / polyurethane composite synthetic leather material may be designed to have a variety of properties considering the content of different layers. For example, it may have excellent flame retardancy, soot concentration, heat resistance, stain resistance, solvent resistance, and hydrolysis resistance, etc., which are required for the end use of leather. The assumed end uses include, but are not limited to, furniture, decoration, handbags, travel bags, clothing, footwear, car interiors, car seats, and medical beds / seats, etc.

Example

[0103] In the following examples, a hydrosilylation-curable silicone elastomer composition for forming a silicone / polyurethane synthetic leather topcoat composition, and a plurality of comparative examples were tested to show the advantages of the coatings described herein regarding the maintenance of gloss after polishing. All viscosities are measured at 25 °C using a spindle appropriate for the viscosity range based on the cup / spindle method of ASTM D1084-16 Method Β, unless otherwise indicated. The alkenyl and / or alkynyl content, as well as the Si-H content, were all determined using quantitative infrared analysis according to ASTM E168.

[0104] The components used in the silicone / polyurethane synthetic leather topcoat composition to be used are defined below, together with the names given in the following table / examples. The vinyl-terminated siloxane polymer is a dimethyl vinyl-terminated polydimethylsiloxane having a viscosity of 65,000 mPa·s at 25 °C and a vinyl content of about 0.08 wt%. The high vinyl siloxane copolymer is a dimethyl vinyl-terminated dimethyl methyl vinyl polysiloxane copolymer having a viscosity of 15,000 mPa·s at 25 °C and a vinyl content of about 8.0 wt%. The vinyl-terminated siloxane copolymer 2 is a dimethylvinyl-terminated dimethylmethylvinylpolysiloxane copolymer having a viscosity of 300 mPa·s at 25°C and a vinyl content of about 1.15 wt%. Fumed silica is HDK® T30P pyrogenic silica (Wacker Chimie) having a BET surface area of 300 m 2 / g. HMDZ is hexamethyldisilazane. MVD (methylvinyldiol) is a dimethylhydroxy-terminated polydimethylmethylvinylsiloxane having a viscosity of about 30 mPa·s at 25°C and a vinyl content of about 12.0 wt%. The platinum catalyst is a platinum catalyst in a solution of polydimethylsiloxane having about 5000 ppm of platinum metal based on the remainder of the composition. The inhibitor is methyl(tris(1,1-dimethyl-2-propynyloxy))silane. The silicone elastomer powder is Dowsil® 23N (Dow Silicones Corporation). The trimethyl-terminated SiH crosslinker is a trimethyl-terminated dimethylmethylhydrogenpolysiloxane copolymer having a viscosity of about 45 mPa·s at 25°C and a silicon-bonded hydrogen content of about 7220 ppm. The resin SiH crosslinker is an Si-H dimethyl-terminated resin Si-H polysiloxane having a viscosity of 25 mPa·s at 25°C and a silicon-bonded hydrogen content of about 9,000 ppm. The ZrAcAc masterbatch is zirconium acetylacetonate in a 50:50 masterbatch of vinyl-terminated siloxypolymer. Silane 1 is 3-glycidoxypropyltrimethoxysilane. Silane 2 is 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione. Silane 3 is bis(trimethoxysilyl)hexane.

[0105] Table 1 provides details of the starting materials used for the silica masterbatch in the compositions described below. Fumed silica is mixed with a vinyl-terminated siloxane polymer in the presence of small molecules that act as hydrophobizing agents for the silica, and in-situ treatment of the silica is carried out while the silica and the polymer are being mixed. As previously indicated, the polymer used may be either component (i) or, if desired, a mixture of component (i) with another polymer, in which case component (i) is not present in the masterbatch.

[0106] [Table 1]

[0107] A plurality of LSR compositions were prepared as Examples (Ex.1 - 11) and Comparative Examples (comp.1 - 9) in a two-part composition.

[0108] Prior to mixing, the following were incorporated into the Part A composition: High vinyl siloxane copolymer, A certain proportion of the masterbatch shown in Table 1, Platinum catalyst, ZrAcAc masterbatch and A certain proportion of an eco-solvent. The eco-solvent is designed to evaporate during the curing process.

[0109] The following were incorporated into the Part B composition: The remainder of the masterbatch, Resin SiH crosslinking agent, If present, inhibitor, as well as silanes 1, 2 and / or 3, and the remainder of the eco-solvent present. The eco-solvent is designed to evaporate during the curing process.

[0110] Immediately prior to use, the Part A composition and each Part B composition were mixed together in a 1:1 weight ratio to produce the final silicone / polyurethane synthetic leather topcoat composition to be tested.

[0111] In the following examples, immediately after mixing, the prepared silicone / polyurethane synthetic leather topcoat composition was applied onto a pre-prepared polyurethane composite material having a cloth support layer, a foamed adhesive layer laminated thereon, and a beige polyurethane (PU) skin layer prepared using a polyether polyol. The topcoat used in each example / comparative example was applied onto the PU skin layer in a furnace at an average temperature of 150 °C and cured for approximately 5 minutes.

[0112]

Table 2a

[0113]

Table 2b

[0114]

Table 3a

[0115]

Table 3b

[0116]

Table 4a

[0117]

Table 4b

[0118] Once cured, the resulting silicone / polyurethane composite synthetic leather material had a topcoat with an average dry film thickness between 20 μm and 25 μm. Upon inspection, the examples were generally found to exhibit a matte appearance.

[0119] All examples were tested for ease of cleaning performance and scratch resistance.

[0120] The ease of cleaning performance was carried out by marking the surface of the cured top coat of the silicone / polyurethane composite synthetic leather material to be tested with a ballpoint pen, and then checking whether all the ballpoint pen marks can be directly cleaned within 5 minutes by using a tissue paper or medical gauze. In the same area of a leather sample, if all the ballpoint pen marks can be completely cleaned more times, it means better ease of cleaning performance.

[0121] The abrasion resistance was carried out according to the FORD FLTM BN 108-13 test, which was designed to determine the resistance to abrasion of the surface of plastics or other materials under standard conditions. In this technique, an abrasion testing machine is used in accordance with the test requirements, and then the observer visually inspects the presence or absence of abrasion lines using a controlled light source and grades them on a rating scale of 1 to 5 (1 = no abrasion lines at all; 5 = significant abrasion lines).

[0122]

Table 5a

[0123]

Table 5b

[0124] Focusing on the fact that after the abrasion resistance test in the comparative example, some delamination was observed after the abrasion step was carried out. This was not observed in the examples. From the results, as the disclosure in Table 5a supports, all the examples had an easy-to-clean performance of at least 4, while on the other hand, the results of the comparative examples in Table 5b gave much worse results. Similarly, the abrasion resistance results were consistently better in the examples herein. The results of stain resistance (easy-to-clean property) herein were considered to be due to the stable bonding between the silicone / polyurethane synthetic leather topcoat composition and the PU skin layer (after the former was cured). One of the main advantages of the silicone / polyurethane composite synthetic leather material is its superiority in manufacturing cost (high performance / price ratio), especially when compared with pure silicone leather, considering the high performance shown. The present specification includes the following inventions. Item 1. A silicone / polyurethane synthetic leather topcoat composition, Component (i), one or more organopolysiloxane polymers having at least two unsaturated groups per molecule, the unsaturated groups being selected from alkenyl groups, alkynyl groups or mixtures thereof, and having a viscosity of 100 to 500,000 mPa·s at 25°C, Component (ii), an inorganic reinforcing filler, such as finely divided silica, optionally hydrophobically treated with one or more filler treating agents, Component (iii), a polyorganosiloxane containing at least two, or at least three silicon-bonded hydrogen (-Si-H) groups per molecule, Component (iv), a hydrosilylation catalyst, Component (v), zirconium acetylacetonate in an amount of 1 to 5% by weight of the composition, and 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione in an amount of 1 to 6% by weight of the composition, and / or a compound of the formula [Chemical formula] [wherein, R 5is an alkyl group having 1 to 6 carbons, R 6 is an alkoxy group having 1 to 6 carbons, z = 0, 1 or 2] one or more epoxy silanes or combinations thereof with mixtures thereof, adhesion promoters, and component (vi), an eco-solvent, and optionally, component (vii), a cured silicone powder A silicone / polyurethane synthetic leather topcoat composition comprising. Item 2. Component (iii) of the hydrosilylation-curable silicone elastomer composition is as follows: Si-H-containing groups, (CH3)3SiO 1 / 2 groups and SiO 4 / 2 groups, or a silicone resin comprising or consisting of these, Si-H-containing groups and SiO 4 / 2 groups, or a silicone resin comprising or consisting of these, Si-H-containing groups, (CH3)2SiO 2 / 2 groups and SiO 4 / 2 groups, or a silicone resin comprising or consisting of these, Si-H-containing groups, SiO 4 / 2 groups and (C6H5)3SiO 1 / 2 groups, or one or more of a silicone resin comprising or consisting of these, each of the above may include one or more CH3-SiO 3 / 2 (T) groups, and alternatives in which methyl is replaced by a phenyl group or other alkyl group or mixtures thereof, The silicone / polyurethane synthetic leather topcoat composition according to item 1. Item 3. The leather coating composition according to item 1 or 2, wherein the cured silicone elastomer powder (vii) has an average particle size of 0.01 to 100 μm. Item 4. The leather coating composition according to any one of items 1 to 3, wherein the eco-solvent (vi) comprises isopentadecane, isohexadecane, isoheptadecane, isooctadecane, isononadecane, and mixtures thereof, or a trimethyl-terminated polydimethylsiloxane having a viscosity of ≧5 mPa·s at 25°C to 100 mPa·s (≦) at 25°C, or consists of these. Item 5. The silicone / polyurethane synthetic leather topcoat composition according to any one of items 1 to 4, wherein the composition further comprises one or more of the following additives: a curing inhibitor, a cured silicone elastomer powder, a pot life extender, a lubricant, a flame retardant, a pigment, a colorant, a heat stabilizer, a compression set improving additive, a noise suppressor, and mixtures thereof. Item 6. The silicone / polyurethane synthetic leather topcoat composition according to any one of items 1 to 5, wherein the epoxy silane of component (v) is selected from 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, (3-glycidoxypropyl)methyldiethoxysilane, and (3-glycidoxypropyl)methyldimethoxysilane. Item 7. A silicone / polyurethane composite synthetic leather material comprising a topcoat which is a reaction product of the composition according to any one of items 1 to 6 upon curing. Item 8. The following layer (a) A fabric support layer; (b) A sponge / adhesive layer adhered to (a); (c) A suitable polyurethane skin layer adhered to the sponge / adhesive layer (b); and (d) A cured product of the silicone / polyurethane synthetic leather topcoat composition according to any one of items 1 to 6 The silicone / polyurethane composite synthetic leather material according to item 7, comprising layers (b) substantially sandwiched between layers (a) and (c), and layer (c) substantially sandwiched between layers (b) and (d). Item 9. A method for preparing a silicone / polyurethane composite synthetic leather material having a top coat, comprising the step of adhering and curing the silicone / polyurethane synthetic leather top coat composition according to any one of items 1 to 6 to a suitable polyurethane skin layer. Item 10. The following steps: applying the polyurethane skin layer (c) onto a release liner and then drying the polyurethane skin layer (c); applying the sponge / adhesive layer (b) onto the skin layer (c) and, before the sponge / adhesive layer (b) is dried or after it is partially dried, applying the fabric support layer (a) by starting lamination on the surface of the sponge layer (b) far from the skin layer (c); removing the release liner if necessary to form a partially prepared silicone / polyurethane composite synthetic leather material, and applying and curing a layer of the silicone / polyurethane synthetic leather top coat composition (d) according to any one of items 1 to 6 onto the polyurethane skin layer (c). A method for preparing a silicone / polyurethane composite synthetic leather material having a top coat according to item 9. Item 11. The following steps: applying the silicone / polyurethane synthetic leather top coat composition according to any one of items 1 to 6 onto a release liner and curing it to form a silicone / polyurethane synthetic leather top coat (d); applying the polyurethane skin layer (c) onto the cured silicone / polyurethane synthetic leather top coat (d) and then drying it; applying the sponge / adhesive layer (b) onto the skin layer (c); and applying the fabric support layer (a) by starting lamination on the surface of the sponge layer (b) far from the skin layer (c) before the sponge / adhesive layer (b) is dried or after it is partially dried. A method for preparing a silicone / polyurethane composite synthetic leather material having a top coat according to item 9. Item 12. A method for preparing a silicone / polyurethane composite synthetic leather material having a top coat according to any one of items 9, 10, or 11, wherein the silicone / polyurethane synthetic leather top coat composition is applied and cured so as to obtain a dry film thickness of about 2 to 50 μm. Item 13. A method for preparing a silicone / polyurethane composite synthetic leather material having a top coat according to any one of items 9, 10, 11, or 12, wherein the silicone / polyurethane synthetic leather top coat composition is applied using one or more techniques selected from spraying, rolling, brushing, spin coating, dip coating, solvent casting, slot die coating, spray coating, knife coating, or gravure coating. Item 14. A method for preparing a silicone / polyurethane composite synthetic leather material having a top coat according to any one of items 9, 10, 11, 12, or 13, wherein the polyurethane skin layer is activated using a suitable activation method selected from plasma treatment, corona discharge treatment, UV-C / ozone, or vacuum-UV irradiation before coating with the silicone / polyurethane synthetic leather top coat composition according to any one of items 1 to 6. Item 15. Use of a silicone / polyurethane composite synthetic leather material prepared by the method according to item 7 or 8, or according to any one of items 9 to 14, in or for furniture, decoration, handbags, travel bags, clothing, footwear, automotive interiors, automotive seats, and medical beds / seats, etc.

Claims

1. A silicone / polyurethane synthetic leather topcoat composition, comprising: Component (i), one or more organopolysiloxane polymers having at least two unsaturated groups per molecule, wherein the unsaturated groups are selected from alkenyl groups, alkynyl groups or mixtures thereof, and having a viscosity of 100 to 500,000 mPa·s at 25°C; Component (ii), an inorganic reinforcing filler optionally hydrophobically treated with one or more filler treatment agents, such as finely divided silica; Component (iii), a polyorganosiloxane containing at least two or at least three silicon-bonded hydrogen (-Si-H) groups per molecule; Component (iv), a hydrosilylation catalyst; Component (v), zirconium acetylacetonate in an amount of 1 to 5% by weight of the composition, and 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione in an amount of 1 to 6% by weight of the composition, and / or a compound of the formula 【Chemical 1】 [wherein, R ５ is an alkyl group having 1 to 6 carbons, R ６ is an alkoxy group having 1 to 6 carbons, and z = 0, 1 or 2], an adhesion promoter containing one or more epoxy silanes of the formula or a combination with a mixture thereof, and Component (vi), isopentadecane, isohexadecane, isoheptadecane, isooctadecane, isononadecane and mixtures thereof, or a trimethyl-terminated polydimethylsiloxane having a viscosity of ≧5 mPa·s at 25°C to 100 mPa·s or less (≦) at 25°C, or consisting of these, an eco-solvent, and optionally, Component (vii), a cured silicone elastomer powder A silicone / polyurethane synthetic leather topcoat composition containing the above components.

2. The component (iii) is as follows: Si-H containing group, (CH ３ ) ３ SiO １／２ group and SiO ４／２ group-containing or consisting of silicone resin, Silicon-hydrogen-containing group and SiO ４／２ A silicone resin containing or consisting of these groups Si-H-containing group, (CH ３ ) ２ SiO ２／２ group and SiO ４／２ group-containing or consisting silicone resin, Si-H-containing group, SiO ４／２ group and (C ６ H ５ ) ３ SiO １／２ containing one or more silicone resins containing or consisting of these groups, Each of the above is one or more CH ３ -SiO ３／２ (T) groups, and may include alternatives in which methyl is replaced by a phenyl group or other alkyl group or mixtures thereof, The silicone / polyurethane synthetic leather topcoat composition according to Claim 1.

3. The leather coating composition according to Claim 1 or 2, wherein the cured silicone elastomer powder (vii) has an average particle size of 0.01 to 100 μm.

4. The composition further contains one or more of the following additives: a curing inhibitor, a cured silicone elastomer powder (vii), a pot life extender, a lubricant, a flame retardant, a pigment, a colorant, a heat stabilizer, a compression set improvement additive, a noise inhibitor and mixtures thereof. The silicone / polyurethane synthetic leather topcoat composition according to any one of Claims 1 to 3.

5. The epoxy silane of component (v) is selected from 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, (3-glycidoxypropyl)methyldiethoxysilane, (3-glycidoxypropyl)methyldimethoxysilane, and the silicone / polyurethane synthetic leather topcoat composition according to any one of claims 1 to 4.

6. A silicone / polyurethane composite synthetic leather material comprising a topcoat that is a reaction product of the composition according to any one of claims 1 to 5 obtained upon curing.

7. The following layers (a) A cloth support layer; (b) A sponge / adhesive layer adhered to (a); (c) A suitable polyurethane skin layer adhered to the sponge / adhesive layer (b); and (d) A cured product of the silicone / polyurethane synthetic leather topcoat composition according to any one of claims 1 to 5 The silicone / polyurethane composite synthetic leather material according to claim 6, comprising, wherein layer (b) is substantially sandwiched between layer (a) and (c), and layer (c) is substantially sandwiched between layer (b) and (d).

8. A method for preparing a silicone / polyurethane composite synthetic leather material having a topcoat, comprising the step of adhering and curing the silicone / polyurethane synthetic leather topcoat composition according to any one of claims 1 to 5 to a suitable polyurethane skin layer.

9. The following steps: applying the polyurethane skin layer (c) onto a release liner and then drying the polyurethane skin layer (c); applying the sponge / adhesive layer (b) onto the skin layer (c) and, before the sponge / adhesive layer (b) is dried or after it is partially dried, applying the cloth support layer (a) to the surface of the sponge layer (b) far from the skin layer (c) by starting the lamination; removing the release liner if necessary to form a partially prepared silicone / polyurethane composite synthetic leather material, and applying and curing a layer of the silicone / polyurethane synthetic leather topcoat composition (d) according to any one of claims 1 to 5 to the polyurethane skin layer (c) A method for preparing a silicone / polyurethane composite synthetic leather material having a topcoat according to claim 8.

10. Next step: Coating the silicone / polyurethane synthetic leather topcoat composition according to any one of claims 1 to 5 on a release liner and curing it to form a silicone / polyurethane synthetic leather topcoat (d); applying the polyurethane skin layer (c) to the cured silicone / polyurethane synthetic leather topcoat (d) and then drying it; applying the sponge / adhesive layer (b) on the skin layer (c); and applying the fabric support layer (a) to the surface of the sponge layer (b) far from the skin layer (c) by starting lamination before the sponge / adhesive layer (b) is dried or after it is partially dried. A method for preparing a silicone / polyurethane composite synthetic leather material having the topcoat according to claim 8.

11. A method for preparing a silicone / polyurethane composite synthetic leather material having the topcoat according to any one of claims 8, 9 or 10, wherein the silicone / polyurethane synthetic leather topcoat composition is applied and cured so as to obtain a dry film thickness of about 2 to 50 μm.

12. A method for preparing a silicone / polyurethane composite synthetic leather material having the topcoat according to any one of claims 8, 9, 10 or 11, wherein the silicone / polyurethane synthetic leather topcoat composition is applied using one or more techniques selected from spraying, rolling, brushing, spin coating, dip coating, solvent casting, slot die coating, spray coating, knife coating or gravure coating.

13. A method for preparing a silicone / polyurethane composite synthetic leather material having the topcoat according to any one of claims 8, 9, 10, 11 or 12, wherein the polyurethane skin layer is activated using a suitable activation method selected from plasma treatment, corona discharge treatment, UV-C / ozone or vacuum-UV irradiation before being coated with the silicone / polyurethane synthetic leather topcoat composition according to any one of claims 1 to 5.

14. Use of a silicone / polyurethane composite synthetic leather material prepared by the method according to claim 6 or 7, or according to any one of claims 8 to 13, in or for furniture, decoration, handbags, travel bags, clothing, footwear, vehicle interiors, vehicle seats and medical beds / seats, etc.

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