Multilayer synthetic leather product

Abstract

A multi-layer synthetic leather product comprising (A) a silicone-based top layer; and (B) a polyurethane-based skin layer formed with a polyurethane dispersion formulation wherein the polyurethane dispersion formulation is formed by blending water, at least one chain extender, and an isocyanate-terminated prepolymer, the isocyanate-terminated prepolymer is the reaction product of a mixture comprising at least one isocyanate compound, at least one polyol compound, and from 2.5% to 15% by weight, based on the weight of the prepolymer, of at least one allyl polyether monoalcohol. As a chemical bond is formed between the top layer and the surface layer, the synthetic leather product exhibits excellent peel resistance, mechanical strength, easy cleaning ability and hand feeling.

Description

Technical Field

[0001] The present disclosure relates to a unique multi-layer synthetic leather product in which a polyurethane-based surface layer and a silicone-based top layer are covalently bonded to each other, thereby imparting the synthetic leather product with significantly enhanced peel resistance while still maintaining excellent mechanical strength, easy cleanability and hand feel. Background Art

[0002] The general technical solution reported in the prior art is to directly coat a silicone-based top coating on the outermost surface of a PU-based leather without an additional chemical bond, so as to produce a semi-silicone PU leather having a multi-layer structure consisting of a fabric layer, a foam layer, a PU-based surface layer, and a silicone-based top layer from bottom to top, and exhibiting the desired easy-to-clean ability and feel. However, a serious problem accompanying this solution is the low adhesion strength between the silicone-based top layer and the surface layer, which will result in poor peeling resistance and poor easy-to-clean ability. Therefore, there has long been a need to develop a unique synthetic leather that has low cost, high peeling resistance, and is still able to achieve the excellent performance of pure silicone-based synthetic leather.

[0003] After continued exploration, we have surprisingly developed a unique multi-layer synthetic leather product that can achieve the above goals. Summary of the invention

[0004] The present disclosure provides a unique multi-layer synthetic leather product and method of making the same.

[0005] In a first aspect of the present disclosure, a multi-layer synthetic leather product comprises:

[0006] (A) a silicone-based top layer which is the reaction product of a polysiloxane formulation comprising a first polysiloxane functionalized with at least one Si-H group and a second polysiloxane functionalized with at least one vinyl group; and

[0007] (B) a polyurethane-based skin layer formed with a polyurethane dispersion formulation, wherein the polyurethane dispersion formulation is formed by blending water, at least one chain extender, and an isocyanate-terminated prepolymer, the isocyanate-terminated prepolymer being the reaction product of a mixture comprising:

[0008] (a) at least one isocyanate compound comprising at least two isocyanate groups;

[0009] (b) at least one polyol compound having a weight average molecular weight of 500 g / mol to 8000 g / mol; and

[0010] (c) 2.5 to 15 wt %, based on the weight of the prepolymer, of at least one allyl polyether monol having allyl groups and hydroxyl groups and having a weight average molecular weight of 500 to 8,000 g / mol. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of a multi-layer synthetic leather product according to one embodiment of the present disclosure, illustrating the mechanism of forming chemical bonds between the surface layer and the top layer. DETAILED DESCRIPTION

[0012] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. In addition, all publications, patent applications, patents, and other references mentioned herein are incorporated by reference.

[0013] As disclosed herein, “and / or” means “and, or as an alternative.” Unless otherwise indicated, all ranges are inclusive.

[0014] Without being bound by any particular theory, the technical breakthrough of the present disclosure lies in the specially designed PUD formulation of the surface layer. In particular, it was found that allyl polyether monol can be used in combination with a polyol component (e.g., a combination of polytetramethylene ether glycol and another polyether polyol) in a reaction with an isocyanate to produce a polyurethane backbone containing at least one terminal or pendant allyl group, which further reacts with reactive groups (e.g., Si-H, Si-OH, Si-CH=CH2) in the top layer, thereby chemically bonding the polyurethane backbone in the surface layer to the siloxane backbone in the top layer and imparting excellent peel resistance to the silicone-PU composite multi-layer synthetic leather product.

[0015] For example, Figure 1 A schematic cross-sectional view of a multi-layer synthetic leather product according to one embodiment is shown, wherein the synthetic leather product comprises, from top to bottom, (A) a silicone-based top layer; (B) a polyurethane-based surface layer; (C) a foam layer; and (D) a fabric layer, wherein all layers are schematic and not to any particular scale. Figure 1In the exemplary embodiment shown in , the allyl groups attached to the polyurethane backbone in the surface layer react with the Si-H groups attached to the siloxane backbone in the top layer to form Si-C covalent bonds between the surface layer and the top layer. Without being limited to any particular theory, it is also estimated that other reactive groups (e.g., Si-OH or Si-CH=CH2) attached to the siloxane backbone in the top layer can also react with the allyl groups attached to the polyurethane backbone in the surface layer to form covalent bonds between the top layer and the surface layer, such as "Si-OC (e.g., through the mechanism of Si-OH+CH2=CH-CH2-polyether alcohol→Si-O-CH2-CH2-CH2-polyether alcohol)" or "CC (e.g., through the mechanism of Si-CH=CH2+CH2=CH-CH2-polyether alcohol→Si-CH2-CH2-CH2-CH2-polyether alcohol)". Figure 1 The subscripts "m" and "n" shown in represent the degree of polymerization of the polysiloxane, wherein each of m and n may independently be an integer from 1 to 2,000, such as 2 to 1,800, or 5 to 1,500, or 10 to 1,200, or 50 to 1,000, or 80 to 800, or 100 to 700, or 200 to 600, or 300 to 500, or 350 to 400, or within a numerical range obtained by combining any two of the aforementioned endpoints.

[0016] According to one embodiment, the skin layer is prepared by coating a layer of the PUD formulation onto release paper and curing the coated layer.

[0017] According to an exemplary embodiment, the PUD may be synthesized by: step A: reacting component (a) with component (b) and component (c) to form a prepolymer containing one or more, for example, one, two, three, four, five, six, seven or more free isocyanate groups; and step B: blending the prepolymer with water and optionally at least one chain extender to form an internally emulsified polyurethane dispersion. According to one embodiment, the chain extender may be incorporated in the above step A, step B, or both. According to a specific embodiment, the chain extender may be incorporated in the above step B. According to one embodiment, the prepolymer formed in the first step may have an isocyanate group content (NCO%) of 1.0 wt % to 10.0 wt %, such as 2.0 wt % to 9.0 wt %, or 3.0 wt % to 8.0 wt %, or 3.5 wt % to 7.0 wt %, or 4.0 wt % to 5.0 wt %, based on the weight of the prepolymer.

[0018] According to one embodiment, the PUD is configured to be internally emulsified. According to another embodiment, the PUD contains only an internal emulsifier and does not contain an external emulsifier. As used herein, the term "internal emulsification" or "internal emulsification" refers to a mechanism in which the emulsification function is substantially or completely contributed by at least one internal emulsifier, which has been covalently integrated into the polyurethane backbone, wherein anionic, cationic or nonionic surfactants / hydrophilic functional groups (such as carboxylic acid groups, sulfonic acids, amine groups, etc.) can be attached to the polyurethane backbone as terminal groups or pendant groups. According to an exemplary embodiment, the internal emulsifier can be a compound comprising at least one hydrophilic group and at least two isocyanate-reactive groups, such as a C2-C4 polyol having at least two hydroxyl groups. 20 Carboxylic acid compounds. Exemplary internal emulsifiers can be selected from the group consisting of dimethylol formic acid, dimethylol acetic acid, dimethylol propionic acid, dimethylol butyric acid, dimethylol valeric acid, dimethylol hexanoic acid, dimethylol heptanoic acid, dimethylol nonanoic acid, dimethylol decanoic acid, dimethylol lauric acid, dimethylol palmitic acid, dimethylol stearic acid, dimethylol cyclohexane carboxylic acid, dimethylol benzoic acid, and any combination thereof. According to a specific embodiment, the internal emulsifier is dimethylol-butyric acid, such as 2,2-dimethylol-butyric acid.

[0019] According to a particular embodiment, the PUD is 100% internally emulsified. In other words, no external emulsifiers / surfactants are added before, during, and after the formation of the PUD.

[0020] According to one embodiment, the content of the internal emulsifier is 1 wt % to 10 wt %, such as in the range of 1.2 wt % to 9 wt %, or in the range of 2.0 wt % to 3.5 wt %, or in the range of 2.7 wt % to 3.0 wt %, based on the weight of the prepolymer.

[0021] In various embodiments, the average NCO functionality of the isocyanate compound of component (a) is greater than 1, such as greater than 1 and less than 4, or from about 1.5 to about 3, or from about 2 to about 3. In some embodiments, component (a) includes an isocyanate compound comprising at least two isocyanate groups. In another embodiment, the isocyanate compound includes an aromatic or aliphatic polyisocyanate having two or more isocyanate groups, such as a linear aliphatic, cycloaliphatic or aromatic aliphatic polyisocyanate having two or more isocyanate groups. In one embodiment, the isocyanate compound is selected from the group consisting of: a C4-C4 polyisocyanate having at least two isocyanate groups. 12 Aliphatic isocyanates, C6-C 15 Cycloaliphatic or aromatic isocyanates, C7-C8- 15Aromatic aliphatic isocyanates and combinations thereof. In another embodiment, the isocyanate compound includes meta-phenylene diisocyanate, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), methylene bis (cyclohexyl isocyanate) (HMDI), hexamethylene-1,6-diisocyanate (HDI), tetramethylene-1,4-diisocyanate, cyclohexane-1,4-diisocyanate, hexahydrotoluene diisocyanate, hydrogenated MDI, naphthylene-1,5-diisocyanate, isophorone diisocyanate (IPDI), or mixtures thereof.

[0022] According to another embodiment, the isocyanate component can be a modified polyfunctional isocyanate, i.e., a product obtained by chemical reaction and modification of the above-mentioned isocyanate compound. Exemplary modified isocyanates are those containing esters, ureas, biuret, isocyanurates, allophanates, carbodiimides and uretonimines, such as 4,4'-carbodiimide-modified MDI products. Liquid isocyanate compounds containing carbodiimide groups, uretonimine groups or isocyanurate rings can also be used, and their isocyanate groups (NCO) content is 10 weight percent to 40 weight percent, such as 20 weight percent to 35 weight percent.

[0023] According to a specific embodiment, component (a) comprises at least 50 wt %, such as 50 wt % to 100 wt %, or 60 wt % to 100 wt %, or 70 wt % 100 wt %, or 80 wt % to 100 wt %, or 90 wt % to 100 wt % IPDI based on the weight of component (a).

[0024] Generally, the amount of component (a) can vary based on the actual requirements of the synthetic leather product. For example, as an illustrative embodiment, the content of component (a) can be about 14 wt % to about 38 wt %, such as about 15 wt % to about 30 wt %, or about 18 wt % to about 25 wt %, or about 19 wt % to about 22 wt %, based on the solid weight of the prepolymer.

[0025] According to another exemplary embodiment, component (b) comprises one or more polyol compounds, such as at least one polyether polyol having a hydroxyl functionality of 2.0 to 3.0 and a weight average molecular weight (Mw) of 100 to 10,000 g / mol, such as 200 to 10,000 g / mol, or 500 to 8,000 g / mol, or 1,000 to 7,000 g / mol, or 1,500 to 5,000 g / mol, or 2,000 to 4,000 g / mol. According to one specific embodiment, component (b) comprises polytetramethylene glycol (PTMEG) having a hydroxyl functionality of 2 and a weight average molecular weight (Mw) of 1,500 g / mol to 3,000 g / mol, such as 2,000 g / mol, wherein the content of PTMEG may be 40 wt % to 70 wt %, such as about 45 wt % to about 68 wt % or about 48 wt % to about 60 wt %, based on the total weight of the prepolymer.

[0026] According to another embodiment, component (b) further comprises one or more polyether polyol compounds other than the above-mentioned PTMEG, such as poly(propylene oxide) glycol, poly(ethylene oxide) glycol, poly(propylene oxide)-co-(ethylene oxide) glycol, etc. For example, the polyether polyol other than PTMEG may include a poly(propylene oxide) glycol having a hydroxyl functionality of 2 and a weight average molecular weight (Mw) of 1,000 g / mol to 5,000 g / mol, such as 1,000 g / mol or 4,000 g / mol. The content of the polyether polyol other than PTMEG used herein may range from about 1 wt % to about 15 wt %, such as about 3 wt % to about 12 wt % or about 5 wt % to about 10 wt %, based on the weight of the prepolymer.

[0027] Alternatively or additionally, component (b) may comprise one or more polyol compounds other than the above-mentioned polyether polyols, and examples thereof may be selected from the group consisting of: C2-C 16 Aliphatic polyols, C6-C 15 Cycloaliphatic polyols, C6-C 15 Aromatic polyols, polyester polyols having a weight average molecular weight of 1,000 g / mol to 8,000 g / mol, polycarbonate diols having a weight average molecular weight of 1,000 g / mol to 8,000 g / mol, and combinations thereof.

[0028] According to another embodiment, one or more monofunctional monomeric alcohols or monofunctional polymeric alcohols may be used in combination with the above-mentioned polyol compounds to prepare the prepolymer.

[0029] According to one embodiment, the allyl polyether monool comprises at least one terminal or pendant allyl group attached to the polyether backbone, and the hydroxyl group can be a primary hydroxyl, a secondary hydroxyl or a combination thereof. The relative content of the allyl group can be 0.5 wt % to 8 wt %, such as 0.8 wt % to 5 wt % or 1 wt % to 3 wt % based on the weight of the allyl polyether monool. According to a specific embodiment, the allyl polyether monool comprises a hydroxyl group and an allyl group, each of which is attached to the end of the polyether backbone. The polyether backbone of the allyl polyether monool can be derived from ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran or their copolymers. According to a specific embodiment, the polyether backbone of the allyl polyether monool can be a homopolymer, such as poly (ethylene oxide), poly (propylene oxide), poly (butylene oxide) or polytetrahydrofuran. According to some embodiments, the polyether backbone of the allyl polyether monol can be a random copolymer, a block copolymer or a graft copolymer polyether chain, and can include poly(ethylene oxide)-co-(propylene oxide), poly(ethylene oxide)-co-(butylene oxide), poly(butylene oxide)-co-(propylene oxide), poly(ethylene oxide)-co-(polytetrahydrofuran), poly(polytetrahydrofuran)-co-(butylene oxide) or poly(polytetrahydrofuran)-co-(propylene oxide). According to another specific embodiment, the polyether backbone of the allyl polyether monol can be a copolymer of poly(ethylene oxide)-co-(propylene oxide), wherein the weight ratio between the ethylene oxide repeating units and the propylene oxide repeating units can be 5 / 95 to 95 / 5, or 10 / 90 to 90 / 10, or 15 / 85 to 85 / 15, or 20 / 80 to 80 / 20, or 25 / 75 to 75 / 25, or 30 / 70 to 70 / 30, or 35 / 65 to 65 / 35, or 40 / 60 to 60 / 40, or 45 / 55 to 55 / 45, or 45 / 55 to 50 / 50, or in the range obtained by combining any two of the above endpoints.

[0030] According to one embodiment, the weight average molecular weight of the allyl polyether monol can be 500 g / mol to 8,000 g / mol, such as 500 g / mol to 6,000 g / mol, or 1,000 g / mol to 4,000 g / mol, or 1,500 g / mol to 3,000 g / mol, or 1,500 g / mol to 2,000 g / mol, or in the range obtained by combining any two of the above endpoints. According to another embodiment, the OH value of the allyl polyether monol can be 20 mg OH / g to 200 mg OH / g, such as 25 mg OH / g to 100 mg OH / g or 30 mg OH / g to 50 mg OH / g.

[0031] Typically, the content of component (c) used herein can range from about 2.5 wt % to about 15 wt %, such as about 2.5 wt % to about 10 wt %, or about 10 wt % to about 15 wt %, or 8 wt % to 12 wt %, based on the weight of the prepolymer.

[0032] According to an optional embodiment, at least one catalyst may be optionally used in the reaction of preparing the above-mentioned prepolymer or the reaction between the prepolymer and the chain extender. The catalyst may include any substance capable of promoting the reaction between the isocyanate group and the isocyanate reactive group, such as organic tin, organic bismuth, tertiary amine, morpholine derivatives, piperazine derivatives and combinations thereof.

[0033] The amount of catalyst used herein is greater than zero and is at most 1.0 wt%, or at most 0.5 wt%, or at most 0.1 wt%, or at most 0.05 wt%, based on the weight of the prepolymer.

[0034] According to another specific embodiment, when an acidic internal emulsifier (e.g., an internal emulsifier having one or more carboxyl groups) is used during the preparation of the prepolymer, it may be necessary to neutralize the prepolymer before blending the prepolymer with water and the chain extender. The neutralizing agent for the prepolymer may include at least one organic base, such as trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, trimethanolamine, triethanolamine, and any combination thereof. The content of the neutralizing agent used herein may be 0.1 wt % to 8 wt %, or 1 wt % to 5 wt %, or 1.5 wt % to 2 wt %, based on the weight of the prepolymer.

[0035] According to various embodiments of this embodiment, the prepolymer may be optionally prepared in the presence of one or more organic solvents, which may appropriately adjust the viscosity, easy-to-clean ability, stability or other fluid properties of the prepolymer system. Without being limited to any particular theory, the PUD may be prepared in the presence of any suitable solvent. According to one embodiment, hazardous and / or flammable solvents such as dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), acetone, etc. are not used in the preparation process of the PUD. According to another embodiment, the PUD does not contain any hazardous and / or flammable solvents. According to a specific embodiment, the organic solvent is environmentally friendly and may include dipropylene glycol dimethyl ether. The content of the organic solvent may be 0 wt % to 50 wt %, or 0.5 wt % to 35 wt %, or 1 wt % to 20 wt %, or 2 wt % to 10 wt %, based on the weight of the prepolymer.

[0036] As described above, the prepolymer thus prepared may be further mixed with a chain extender and water, thereby causing a reaction between the prepolymer and the chain extender to extend the polyurethane chain and increase its molecular weight, and the polyurethane particles thus obtained are dispersed in water or an aqueous solvent to form a PUD. According to one embodiment, the chain extender may include an amine-based chain extender such as propylenediamine (PDA), aminoethylethanolamine (AEEA), hexamethylenediamine (HDA), polyetheramine, aminosiloxane, and any combination thereof.

[0037] According to one embodiment, the chain extender may be used in the form of an aqueous solution or dispersion having a solid content of about 20 wt % to 40 wt %.

[0038] According to a specific embodiment, the chain extender can be a polyetheramine having an amino functionality of about 2.0 to 3.0 and a weight average molecular weight of 150 to 600 g / mol, or 200 to 300 g / mol, or 230 to 300 g / mol. Specific examples of the polyetheramine can include Jeffamine D-230, Jeffamine D-400, Jeffamine ED-600, and any combination thereof.

[0039] Alternatively or additionally, the chain extender may include an aminosilicone, such as a hydrophilic aminosilicone compound comprising an organosilicon-oxygen backbone chain connected to nitrogen-containing side chains and hydrophilic side chains. For example, the hydrophilic aminosilicone compound may have a molecular structure represented by Formula I:

[0040]

[0041] wherein each R independently represents methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, cyclohexyl, phenyl, tolyl, vinyl, allyl or -(OCH2CH2) (1-10) -O-CH2-CH=CH2;

[0042] R1 is -(CH2) (1-10) NH2 or -(CH2) (1-10) -NH-(CH2) (1-10) NH2;

[0043] R2 is -CH2CH2CH2O(CH2CH2O) a H; and

[0044] wherein x is an integer from 20 to 500, such as from 20 to 200, or from 50 to 150, or from 80 to 120, or from 90 to 100; y is an integer from 1 to 20, or from 1 to 10, such as from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20; z is an integer from 1 to 20, or from 1 to 10, such as from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20; t is an integer from 1 to 10, or from 1 to 5, such as from 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10; and a is an integer from 1 to 30, such as from 5 to 20, or from 10 to 15. A specific example of a hydrophilic aminosiloxane chain extender may include XIAMETER OFX-7700.

[0045] According to another embodiment, the content of the chain extender is configured so that the molar ratio between the amine groups in the chain extender and the free NCO groups remaining in the prepolymer is in the range of 2:100 to 99:100, such as 10:100 to 90:100, or 20:100 to 80:100, or 30:100 to 70:100, or 40:100 to 60:100.

[0046] Water (such as deionized water) can be used to prepare PUD. The content of water can be appropriately selected so that the PUD has a suitable polyurethane particle solid loading, such as 20% to 70% by weight, or 30% to 60% by weight, or 40% to 45% by weight. According to a specific embodiment, the polyurethane dispersion formulation comprises 35% to 60% by weight of water, 1% to 25% by weight of chain extender and 20% to 60% by weight of prepolymer based on the total weight of the polyurethane dispersion formulation; wherein the content of water can be 40% to 50% by weight, or 42% to 48% by weight, the content of chain extender can be 5% to 25% by weight, or 10% to 22% by weight, or 15 to 20% by weight, and the content of prepolymer can be 25% to 50% by weight, or 30% to 45% by weight, or 32% to 40% by weight.

[0047] The PUD may optionally contain a rheology modifier, such as a thickener, which can adjust the viscosity of the PUD to a range suitable for applying the top layer to the release paper. Examples of useful rheology modifiers include methylcellulose ethers, alkali swellable thickeners (e.g., sodium or ammonium neutralized acrylic polymers), hydrophobically modified alkali swellable thickeners (e.g., hydrophobically modified acrylic copolymers), associative thickeners (e.g., hydrophobically modified ethylene oxide-based urethane block copolymers), and methylcellulose ethers. The amount of thickener can be about 0.1 wt % to about 5 wt %, or about 0.2 wt % to about 2 wt %, or about 0.3 wt % to about 1 wt %, based on the total weight of the PUD. According to another embodiment, no thickener / rheology modifier is added to the PUD.

[0048] Typically, the waterborne PUD has a viscosity of at least about 10 cp to at most about 10,000 cp, or from about 30 cp to about 3000 cp.

[0049] In one embodiment, the dispersion of the polyurethane particles in the aqueous PUD can be facilitated by high shear stirring, wherein the shear force and stirring speed can be appropriately adjusted based on specific needs.

[0050] According to one embodiment, the water-based PUD may also include one or more pigments, dyes and / or colorants, all of which are generally referred to as "masterbatches" in the present disclosure. Examples of pigments, dyes and / or colorants may include iron oxide, titanium oxide, carbon black and mixtures thereof. The amount of the pigment, dye and / or colorant may be 0.1 wt % to 15 wt %, or 0.5 wt % to 10 wt %, or 1 wt % to 5 wt % based on the total weight of the PUD. Additional additives such as crosslinkers (such as aziridine-type crosslinkers), slip agents, leveling agents, slow drying agents (such as propylene glycol), wetting agents, feel agents, co-solvents, foam stabilizers, antifoaming agents, defoaming agents (such as silicones) may also be appropriately selected and incorporated into the PUD formulation based on the requirements for synthetic leather applications.

[0051] According to one embodiment, the release paper can be coated with the above-mentioned PUD layer until the wet film thickness is about 100 μm to 500 μm, such as 150 μm to 400 μm or 250 μm to 300 μm; then dried in an oven at an elevated temperature of about 60°C to 160°C, or 80°C to 130°C, or 90°C to 100°C for a duration of 10 seconds to 30 minutes, such as 30 seconds to 20 minutes, or 1 minute to 15 minutes, or 5 minutes to 8 minutes; then the release paper and the dried PUD surface layer are removed from the oven and cooled. After applying the foam layer to the surface layer and the fabric layer to the foam layer, a precursor leather without a silicone-based top layer is obtained, and then a silicone formulation layer can be applied to the top surface of the surface layer and cured, thereby forming a synthetic leather product.

[0052] According to one embodiment, the silicone formulation used to prepare the top layer comprises a first polysiloxane functionalized with at least one Si-H group. According to one embodiment, the first polysiloxane is functionalized with one, two, three, four, five, six or more Si-H groups and has a degree of polymerization ranging from about 5 to 1,000, such as 50 to 700 or 200 to 500. According to another embodiment, the silicone formulation used for the top layer may also comprise a second polysiloxane functionalized with at least one vinyl group. According to one embodiment, the second polysiloxane is functionalized with one, two, three, four, five, six or more vinyl groups and has a degree of polymerization ranging from about 2 to 2,000, such as 100 to 1,200, or 300 to 800, or 400 to 700. According to one embodiment, the silicone formulation for the top layer may include 10 to 70 wt % of the first polysiloxane, 10 to 70 wt % of the second polysiloxane, and 10 to 50 wt % of at least one solvent, based on the total weight of the silicone formulation.

[0053] According to one embodiment, the content of the first polysiloxane can be 10 wt % to 70 wt %, such as 30 wt % to 60 wt % or 40 wt % to 50 wt %, based on the total weight of the silicone formulation. According to another embodiment, the content of the second polysiloxane can be 10 wt % to 70 wt %, such as 20 wt % to 65 wt % or 50 wt % to 60 wt %, based on the total weight of the silicone formulation. According to another embodiment, the solvent can be selected from the group consisting of water (e.g., deionized water, monohydric alcohol, diol, or a combination thereof), and can be present in an amount of about 10 wt % to 50 wt %, such as 20 wt % to 40 wt % or 20 wt % to 30 wt %, based on the total weight of the silicone formulation.

[0054] According to additional embodiments, the silicone formulation for the top layer may optionally include one or more additional additives or adjuvants, such as 0 wt % to 50 wt % of a third polysiloxane comprising one or more silanol groups, 0 wt % to 30 wt % of a flame retardant, 0 wt % to 35 wt % of a filler (such as hollow ceramic particles having a volume average particle size in the range of 25 μm to 300 μm), and a catalytic amount of a hydrosilylation catalyst.

[0055] According to an exemplary embodiment, the hydrosilylation catalyst may be a platinum-based catalyst, such as chloroplatinic acid, and is used in a catalytic amount, typically in the range of 0.5 ppm to 200 ppm Pt based on the total weight of the silicone formulation.

[0056] According to another exemplary embodiment, the silicone formulation for the top layer can be a two-part formulation, wherein the first polysiloxane and the hydrosilylation catalyst can be included in Part A, and the second polysiloxane is included in Part B. Examples of commercially available liquid silicones suitable for the top layer include Dowsil LCF 8300 and Dowsil LCF 8500, both available from Dow.

[0057] According to one embodiment, the top layer can be formed by coating the exposed surface of the polyurethane-based top layer with the above-mentioned silicone formulation to a wet film thickness of about 1 μm to 100 μm, such as 5 μm to 50 μm or 8 μm to 20 μm; and then heating the coated laminate in an oven at an elevated temperature of about 100°C to 160°C, or 120°C to 160°C, or 140°C to 150°C for a duration of 10 seconds to 30 minutes, such as 30 seconds to 20 minutes, or 1 minute to 10 minutes, or 2 minutes to 10 minutes; thereby producing a multi-layer synthetic leather product.

[0058] Suitable peeling layers are generally referred to as "peeling papers" in the prior art. Examples of suitable peeling layers include foils of metal, plastic or paper. The peeling layer generally has a thickness of 0.001 mm to 10 mm, preferably 0.01 mm to 5 mm, and more preferably 0.1 mm to 2 mm. The material and thickness of the peeling layer can be appropriately adjusted as long as the peeling layer can withstand the chemical reaction, mechanical processing and heat treatment experienced during the manufacturing process, and can be easily peeled off from the resulting synthetic leather without causing peeling between the surface layer and the foam layer.

[0059] According to one embodiment, the foam layer can be formed by 1K PU foam, 2K PU foam, mechanically foamed PU foam, preferably non-solvent PU foam, and includes a continuous PU matrix defining a plurality of holes and / or pores therein. According to one embodiment, a mechanically foamed PU material (such as an aqueous dispersion of PU, and in particular SCISKY KT-650 available from Scisky) can be blended with one or more processing aids selected from the group consisting of surfactants, emulsifiers, thickeners, foaming agents, catalysts, dispersants, dispersing aids, foam stabilizers and fillers under mechanical stirring, and the blend is applied to the surface layer to form a foam layer. Then the fabric layer is applied to the foam layer with the assistance of a pressure roller. After applying any one of the surface layer, foam layer and fabric layer, one or more curing steps can be performed. According to one embodiment, the peeling layer is removed after the fabric layer, foam layer and surface layer have been applied or before the top layer is applied. The peeling layer can be peeled off by any common technique.

[0060] In one embodiment, the fabric layer may have a thickness in the range of 0.01 mm to 50 mm, such as in the range of 0.05 mm to 10 mm or in the range of 0.1 mm to 5 mm. The fabric layer may comprise one or more materials selected from the group consisting of: a fabric (such as a woven or non-woven fabric), an impregnated fabric, a knitted fabric, a braided fabric or a microfiber; a foil of metal or plastic, for example rubber, PVC or polyamide; and leather, such as split leather.

[0061] According to one embodiment, the fabric layer can be made of woven or nonwoven textiles. Suitable fiber materials include, but are not limited to, synthetic fiber materials and natural or semi-synthetic fiber materials and their mixtures or blends. The example of synthetic fiber materials includes polyester, polyamide, acrylic, polyolefin, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol and their blends or mixtures. The example of natural semi-synthetic fiber materials includes cotton, wool and hemp.

[0062] According to various embodiments, each layer of the synthetic leather product may be applied by conventional coating techniques, such as spray coating, knife coating, die coating, cast coating, dip coating, roller coating, and the like.

[0063] The multilayer structure synthetic leather disclosed herein can be cut or otherwise shaped to have a shape suitable for any desired purpose (such as sofa manufacturing).Depending on the expected application, the synthetic leather can be further processed or post-processed similar to genuine leather, such as by brushing, filling, milling or ironing.If desired, synthetic leather (such as genuine leather) can be arranged with a conventional finishing composition.This provides further possibilities for controlling its characteristics.Multilayer structure disclosed herein can be used in various applications particularly suitable for use as synthetic leather, such as clothing, sofas, gloves, handbags, luggage, wallets, belts, furniture decoration, indoor or outdoor decoration, automotive parts, medical equipment and electronic devices.

[0064] Example

[0065] Some embodiments will now be described in the following examples, in which all parts and percentages are by weight unless otherwise indicated. However, the scope is not limited to the formulations described in these examples. Instead, the examples are intended only to illustrate the present disclosure.

[0066] The information of the raw materials used in the examples is listed in Table 1 below:

[0067] Table 1. Raw materials used in the examples

[0068]

[0069]

[0070] Preparation Example A: Preparation of prepolymer

[0071] The prepolymers used in Inventive Examples (IE) 1-3 and Comparative Examples (CE) 1-4 were prepared by the following procedure: polyols (including PTMEG-2000 and VORANOL TM 4000LM), internal emulsifier (DMBA) and allyl polyether monool (KH-15A) or comparative corresponding reagent (HDPOL-1500M) were charged into a 500mL three-necked flask and dehydrated at 115°C and 76mmHg pressure for 0.5 hours, and then the dehydrated polyol mixture was naturally cooled to a temperature of 60°C. A specific amount of IPDI was weighed according to Table 2 and poured into the dehydrated polyol mixture at the same temperature, under nitrogen (N2) flow protection and mechanical stirring, and then 0.05g of catalyst was added. MB20 was added to the flask. The reaction was continued at 70°C for about 30 minutes, then heated to 80°C and continued to react at this temperature for 3 hours. The reaction system was cooled to a temperature below 60°C, and then 2.9 g of DMM was added thereto. After stirring for 20 minutes, 1.56 g of TEA was added for neutralization. The reaction system was stirred for another 10 minutes, thereby producing a prepolymer, which was transferred to a plastic cup (3 L) to prepare a polyurethane dispersion.

[0072] Table 2. Formulations of prepolymers of IE 1-3 and CE 1-4, where all amounts are described in grams.

[0073] raw materials CE 1 CE 2 CE 3 CE 4 IE 1 Internet Explorer 2 Internet Explorer 3 DMBA 2.86 2.86 2.86 2.86 2.86 2.86 2.86 KH-15A 17.5 0 1 0 15 10 2.5 HDPOL-1500M 0 10 0 0 0 0 0 PTMEG 2000 46.09 51.69 60.28 61.05 48.24 52.55 58.99 <![CDATA[VORANOL TM 4000LM]]> 9.53 9.53 9.53 9.53 9.53 9.53 9.53 Total amount of polyols 75.98 74.08 73.67 73.44 75.63 74.94 73.88 IPDI 19.5 21.40 21.81 22.04 19.85 20.54 21.6 Dabco MB20 0.05 0.05 0.05 0.05 0.05 0.05 0.05 DMM 2.91 2.91 2.91 2.91 2.91 2.91 2.91 TEA 1.56 1.56 1.56 1.56 1.56 1.56 1.56 Total amount of PU prepolymer 100.00 100.00 100.00 100.00 100.00 100.00 100.00

[0074] Preparation Example B: Preparation of PUD

[0075] The internal emulsified polyurethane dispersions of IE 1-3 and CE 1-4 were prepared by using the prepolymer prepared as above according to the following procedure: 100 g of the prepolymer was transferred to a 1 L plastic beaker and stirred at 3000 rpm with a gear-shaped dispersion plate. Ice water was added to the plastic beaker and then stirred for another 5 minutes before an emulsion was formed and the stirring speed was reduced to 2000 rpm. D-230 40% aqueous solution and XIAMETER TM A mixture of 20% aqueous solution of OFX-7700 Fluid was gradually added to the emulsion. The emulsion was then further stirred for another 15 minutes, thereby producing a PUD, which was kept in a plastic beaker covered with a lid to degas overnight. The next day, the material was filtered through a #100 mesh, thereby producing a final PUD product with a solid content of 40%. The relative amounts of the ingredients used to prepare the PUD are summarized in Table 3.

[0076] Table 3. Formulation of polyurethane dispersions

[0077]

[0078]

[0079] Preparation Example C: Preparation of a single PU film by using PUD

[0080] The internal emulsified polyurethane dispersions of IE 1-3 and CE 1-4 prepared as above were used to prepare separate PU films for characterization of mechanical properties such as tensile strength, elongation at break, and modulus at 100% elongation. In particular, 15 g of PUD was transferred to a high-speed mixer and degassed by stirring at 3000 rpm for 3 minutes. Then 1 g of the degassed PUD was poured onto the surface of a plastic petri dish. After drying overnight at room temperature, the dish was transferred to an oven and further dried at 54°C for 24 hours. The film was then peeled off, flipped over and further dried at 54°C for another 24 hours, after which the film was cooled to ambient temperature for further characterization.

[0081] Preparation Example D: Preparation of synthetic PU leather without silicone-based top layer

[0082] Each of the polyurethane dispersions of IE 1-3 and CE 1-4 was blended with a color paste, a crosslinker, a thickener, a leveling agent, a wetting agent, a feel modifier and an antifoaming agent according to the formulation shown in Table 4 and the mixture was mixed at high speed (3000 rpm) for several minutes. The PUD-based coating material thus formulated was coated on a release paper to a wet film thickness of 100 μm. The coated release paper was dried in an oven at 100° C. for 5 minutes. The release paper with the dried PUD surface layer was taken out of the oven and cooled to ambient temperature. A PUD foam layer having a foaming ratio of 250% (see Table 5) by mechanical foaming was coated on the dried PU surface layer to a wet film thickness of 400 μm. The release paper with the PU surface layer and the coated foam layer was transferred to a 130° C. oven and precured for 10 minutes. The PU foam layer was then coated again on the coated release paper having the same thickness, and the fabric was carefully placed on the wet foam layer and pressed twice with a 1 kg roller. The leather specimen was then placed in a 130°C oven and post-cured for 10 minutes before being taken out and cooled. The release paper was peeled off to obtain a PU-based synthetic leather sample without the silicone-based top layer.

[0083] Table 4. Formulations of PU-based skin layers

[0084]

[0085]

[0086] Table 5. Formulation of the foam layer

[0087] Function Components Dosage (g) PU resin SCISKY KT-650 100 Foam stabilizer ORTEGOL EP-P 112 4 Thickener ACUSOL 830 2

[0088] Preparation Example E: Preparation of synthetic leather with silicone-based top layer

[0089] In this preparation example, a silicone-based top layer was applied to the exposed surface of the PU-based surface layer of each of the synthetic leathers of IE 1-3 and CE 1-4 prepared as above. Specifically, 10 g of SILASTIC LCF TM 8700 Part A (contains Pt catalyst) and 10g SILASTIC TM LCF 8700 Part B were blended together for 3 minutes. The mixture was then applied to the exposed surface of the PU-based surface layer of each synthetic leather of IE 1-3 and CE 1-4 prepared as above to a wet thickness of about 5 μm. The entire sample was transferred to an oven and cured at 140°C for 5 minutes, after which the sample was removed from the oven and cooled to ambient temperature, thereby obtaining the final semi-Si synthetic leather.

[0090] Two additional comparative examples CE 5 and CE 6 were conducted, in which a silicone-based top layer was applied to the exposed surface of the PU-based surface layer of the synthetic leather of IE 1, except that the silicone-based top layer of CE 5 contained only 20 g of SILASTIC LCF 8700 Part A and the silicone-based top layer of CE 6 contained only 20 g of SILASTIC LCF 8700 Part B.

[0091] The synthetic leather prepared in CE 5 showed poor adhesive strength between the surface layer and the top layer, and the top layer was easily peeled off from the surface layer after several windings and bendings.

[0092] Regarding the synthetic leather prepared in CE 5, despite the heating and curing treatment at elevated temperature, the top layer remained uncured even for several days, and the outer surface of the top layer was sticky and wet.

[0093] Techniques used to characterize the product

[0094] The PUDs, PU films, and synthetic leather samples of the Inventive Examples and Comparative Examples were characterized by the following techniques.

[0095] (a) Particle size in polyurethane dispersion

[0096] The particle size of the PU particles in the polyurethane dispersion was evaluated by using a Zetasizer-Beckman LS230 particle size analyzer.

[0097] (b) Viscosity of polyurethane dispersion

[0098] The viscosity of the polyurethane dispersion is evaluated by using a Brookfield viscometer at a temperature set at 25° C. Select the S64 spindle and set the speed to 100 rpm. During the test, the calibration line on the spindle should be placed below the liquid level.

[0099] (c) Appearance of polyurethane dispersion

[0100] The polyurethane dispersion was transferred into a transparent plastic bottle and observed with the naked eye through the transparent bottle wall.

[0101] (d) Mechanical properties of PU film alone

[0102] The mechanical properties of the individual PU films, including tensile strength, elongation at break, and modulus at 100% elongation, were evaluated according to ASTM D412-15a.

[0103] (e) Hand feel properties of synthetic leather without top layer

[0104] The hand feel properties of the synthetic leather without the top layer were evaluated by a panel of ten professionals who graded the leather samples based on visual inspection and hand touch on a scale from 1 to 5, and calculated and reported an average score for each sample, where 5 represents a dry and clean surface with good hand feel and 1 represents a sticky and wet surface with poor strength.

[0105] (f) Easy-to-clean ability of synthetic leather with top layer

[0106] The easy-to-clean ability of synthetic leather with a top layer is characterized by drawing a pattern on the top layer surface with an oil pen and then wiping the pattern with tissue paper. Repeat the above drawing-wiping cycle until the pattern is no longer cleanable. The number of cycles is recorded and reported as a means of evaluating the easy-to-clean ability. The larger the value, the better the cleaning ability, and a qualified synthetic leather requires at least 10 cycles.

[0107] The characterization results of all the inventive examples and comparative examples are summarized in Table 6 below.

[0108] Table 6. Characterization results of IE 1-3 and CE1-5

[0109]

[0110]

[0111] As can be seen from the characterization results summarized in Table 6, all of the inventive examples exhibited better performance characteristics, including better mechanical strength, excellent hand feel, and enhanced easy-to-clean capabilities. In contrast, none of the comparative examples were able to achieve excellent results in all performance aspects, and each of the comparative examples exhibited at least one unacceptable and poor result in the above characteristics.

[0112] Furthermore, comparison of IE 2 with IE 1 and IE 3 demonstrates that the relative amount of the allyl polyether monol component can be adjusted to an optimized level (of IE 2) to achieve a significant improvement in easy-to-clean capability relative to the other two inventive examples IE 1 and IE 3.

Claims

1. A multi-layer synthetic leather product comprising: (A) a silicone-based top layer, the silicone-based top layer being the reaction product of a polysiloxane formulation comprising a first polysiloxane functionalized with at least one Si—H group and a second polysiloxane functionalized with at least one vinyl group; as well as (B) a polyurethane-based skin layer formed with a polyurethane dispersion formulation, wherein the polyurethane dispersion formulation is formed by blending water, at least one chain extender, and an isocyanate-terminated prepolymer, the isocyanate-terminated prepolymer being the reaction product of a mixture comprising: (a) at least one isocyanate compound comprising at least two isocyanate groups; (b) at least one polyol compound having a weight average molecular weight of 500 g / mol to 8000 g / mol; as well as (c) 2.5 to 15 wt % based on the weight of the prepolymer of at least one allyl polyether monol having allyl groups and hydroxyl groups and having a weight average molecular weight of 500 to 8,000 g / mol.

2. The multi-layer synthetic leather product according to claim 1, wherein the top layer is chemically bonded to the surface layer through at least one bond selected from the group consisting of Si-C covalent bond, Si-O-C covalent bond, CC covalent bond, and any combination thereof. 3 . The multi-layer synthetic leather product according to claim 1 , wherein the multi-layer synthetic leather product further comprises (C) a foam layer; and (D) a fabric layer.

4. The multi-layer synthetic leather product according to claim 1, wherein the polyurethane dispersion formulation is internally emulsified and comprises 35 wt % to 60 wt % of water, 1 wt % to 25 wt % of the chain extender and 20 wt % to 60 wt % of the prepolymer, based on the total weight of the polyurethane dispersion formulation.

5. The multi-layer synthetic leather product according to claim 1, wherein the prepolymer is the reaction product of: (a) 14 to 38 wt. %, based on the weight of the prepolymer, of an aliphatic isocyanate containing at least two isocyanate groups; (b) 40 to 70 wt % based on the weight of the prepolymer of a polytetramethylene ether glycol having a weight average molecular weight of 1,500 to 3,000 g / mol, and 1 to 15 wt % based on the weight of the prepolymer of at least one polyether polyol compound different from the polytetramethylene ether glycol and having a weight average molecular weight of 3,000 to 5,000 g / mol; and (c) 8 to 12 wt% of the at least one allyl polyether monol having allyl groups and hydroxyl groups and having a weight average molecular weight of 1,000 to 3,000 g / mol, based on the weight of the prepolymer. 6 . The multi-layered synthetic leather product according to claim 4 , wherein the isocyanate compound comprises 50 wt % to 100 wt % of isophorone diisocyanate based on the weight of component (a).

7. The multi-layer synthetic leather product according to claim 1, wherein the chain extender comprises a polyetheramine having an amino functionality of 2 and a weight average molecular weight of 150 g / mol to 600 g / mol, and an aminosilicone; and The molar ratio between the amine groups in the chain extender and the NCO groups in the prepolymer is in the range of 2:100 to 99:

100.

8. The multi-layered synthetic leather product according to claim 1, wherein the reaction for preparing the prepolymer further comprises 1 to 10 wt% of 2,2-dimethylolbutyric acid as an internal emulsifier based on the weight of the prepolymer.

9. The multi-layer synthetic leather product of claim 1, wherein the silicone formulation comprises, based on the total solid weight of the silicone formulation, (i) 10 to 70 weight percent of the first polysiloxane, the first polysiloxane being functionalized with at least one Si-H group and having a degree of polymerization ranging from 5 to 1,000; and (ii) 10 to 70 wt% of the second polysiloxane, the second polysiloxane being functionalized with at least one Si-vinyl group and having a degree of polymerization ranging from 2 to 2,000.

10. The multi-layer synthetic leather product of claim 1, wherein the multi-layer synthetic leather product is selected from the group consisting of clothing, sofas, gloves, handbags, luggage, wallets, belts, furniture upholstery, indoor or outdoor decoration, automotive parts, medical devices, and electronic devices.

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