Internally emulsified polyurethane dispersions and methods for making the same

Abstract

An internally emulsified polyurethane dispersion is provided, which is prepared by using a combination extender system of a hydrophilic aminosiloxane compound and a polyether amine compound. The internally emulsified polyurethane dispersion can be used to prepare a synthetic leather product having good adhesion resistance, wrinkle resistance, color fastness, and excellent mechanical properties. Also provided is a laminated synthetic leather article prepared with the internally emulsified polyurethane dispersion and a method for preparing the synthetic leather article.

Description

Technical Field

[0001] This disclosure relates to an internally emulsified polyurethane dispersion (PUD), a method for preparing the dispersion, and a laminated synthetic leather article comprising a skin film obtained from the polyurethane dispersion. The laminated synthetic leather article prepared from said polyurethane dispersion exhibits excellent anti-sticking properties, wrinkle resistance, color fastness, and mechanical properties. Background Technology

[0002] Synthetic leather is widely used in daily life, from clothing, footwear, bags, home décor to car seats. It offers similar performance and feel to natural leather, but with a greater cost advantage. Synthetic leather typically consists of a top layer, a middle foam layer, and a bottom fabric layer, and can be manufactured by coating the middle foam layer and the bottom fabric layer with one or more polymers, the most commonly used being polyurethane. Traditional processes use dispersions of one or more polyurethane resins in volatile organic solvents such as dimethylformamide (DMF), methyl ethyl ketone (MEK), and toluene; these dispersions are known as solvent-based PU dispersions. However, volatile organic solvents are extremely harmful to factory operators, consumers, and the environment. Therefore, the synthetic leather industry is moving towards solvent-free processing methods to minimize the use of volatile organic solvents in the manufacture of PU synthetic leather.

[0003] Several waterborne polyurethane dispersions (PUDs) have been reported as green alternatives to solvent-based PU dispersions, but none of these PUDs can produce a PU surface exhibiting a combination of various industrial CTQs (critical qualities), including excellent wrinkle resistance, anti-tack, abrasion resistance, softness, color fastness, hand feel, and mechanical properties. In fact, all existing PUDs require trade-offs between at least one performance characteristic to produce a "less undesirable" synthetic leather product. Furthermore, existing PUDs are only effective at low solids contents, such as 45% by weight or less, which results in a poor surface appearance. There remains a pressing need for unique PUDs that overcome all the drawbacks described above.

[0004] After continuous exploration, we have developed an internally emulsified PUD using a combination of chain extender systems, which can solve the above-mentioned performance trade-offs in synthetic leather, that is, high solids content, good wrinkle resistance, good anti-sticking and good color fastness, while maintaining good hand feel (or relatively low modulus) and other good mechanical properties. Summary of the Invention

[0005] This disclosure provides a unique aqueous polyurethane dispersion and a laminated synthetic leather product prepared using the dispersion.

[0006] In a first aspect of this disclosure, an internally emulsified polyurethane dispersion comprising polyurethane particles dispersed in water is provided, wherein the polyurethane dispersion is derived from starting materials comprising:

[0007] Component (A): One or more compounds having at least two isocyanate groups;

[0008] Component (B): One or more compounds having at least two isocyanate reactive groups;

[0009] Component (C): Hydrophilic aminosiloxane compound represented by formula I:

[0010]

[0011] 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). a -O-CH2-CH=CH2;

[0012] R1 is -(CH2) m NH2 or -(CH2) s -NH-(CH2) t NH2;

[0013] R2 is -CH2CH2CH2O(CH2CH2O) n H; and

[0014] Each of R3, R4, R5, R6, and R7 is independently selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, cyclohexyl, phenyl, and tolyl;

[0015] Where a is an integer from 1 to 10; x is an integer from 20 to 500; y is an integer from 1 to 20; z is an integer from 1 to 20; m is an integer from 1 to 10; s is an integer from 1 to 10; t is an integer from 1 to 10; and n is an integer from 5 to 30;

[0016] Component (D): Polyetheramine compound represented by Formula II:

[0017]

[0018] Each of R8 and R9 is independently selected from the group consisting of: hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, cyclohexyl, phenyl, tolyl, and combinations thereof, and q is an integer from 2 to 20;

[0019] Component (E): C2-C having at least two hydroxyl groups 20 Carboxylic acid compounds;

[0020] Component (F) catalyst;

[0021] Component (G) neutralizer; and

[0022] Component (H) Water.

[0023] According to one embodiment of this disclosure, the internally emulsified polyurethane dispersion is water-based.

[0024] According to another embodiment of this disclosure, the polyurethane dispersion does not contain an external emulsifier.

[0025] According to another embodiment of this disclosure, the polyurethane dispersion has a solids content of more than 45% by weight, more than 48% by weight, or at least 50% by weight based on the total weight of the polyurethane dispersion.

[0026] According to another embodiment of this disclosure, one or more compounds having at least two isocyanate groups in component (A) are selected from the group consisting of:

[0027] a) C4-C12 aliphatic polyisocyanates containing at least two isocyanate groups, C6-C15 alicyclic or aromatic polyisocyanates containing at least two isocyanate groups, C7-C15 aromatic aliphatic polyisocyanates containing at least two isocyanate groups, and combinations thereof.

[0028] b) A modified polyfunctional isocyanate derived from one or more polyisocyanates of a), wherein the modified polyfunctional isocyanate comprises at least one functional group selected from the group consisting of: ester group, urea group, biuret group, isocyanurate group, urethane group, carbodiimide group, urea ketimide group, and combinations thereof; and

[0029] c) An isocyanate prepolymer prepared by reacting one or more polyisocyanates of a) with one or more isocyanate reactive compounds selected from the group consisting of: C2-C16 aliphatic polyols containing at least two hydroxyl groups, C6-C15 alicyclic or aromatic polyols containing at least two hydroxyl groups, C7-C15 aryliphatic polyols containing at least two hydroxyl groups, polyester polyols with a molecular weight of 500 to 5,000, polycarbonate diols with a molecular weight of 200 to 5,000, polyether diols with a molecular weight of 200 to 5,000, C2 to C10 polyamines containing at least two amino groups, C2 to C10 polythiols containing at least two thiol groups, C2-C10 alkanolamines containing at least one hydroxyl group and at least one amino group, and combinations thereof, provided that the isocyanate prepolymer contains at least two free isocyanate end groups.

[0030] According to another embodiment of this disclosure, one or more compounds of component (B) having at least two isocyanate reactive groups are selected from the group consisting of: C2-C16 aliphatic polyols containing at least two hydroxyl groups, C6-C15 alicyclic or aromatic polyols containing at least two hydroxyl groups, C7-C15 aryliphatic polyols containing at least two hydroxyl groups, polyester polyols with a molecular weight of 500 to 5,000, polycarbonate diols with a molecular weight of 200 to 5,000, polyether polyols with a molecular weight of 200 to 5,000, C2 to C10 polyamines containing at least two amino groups, C2 to C10 polythiols containing at least two thiol groups, C2-C10 alkanolamines containing at least one hydroxyl group and at least one amino group, vegetable oils having at least two hydroxyl groups, and combinations thereof.

[0031] According to another embodiment of this disclosure, component (E) has a C2-C structure having at least two hydroxyl groups. 20 The carboxylic acid compound is selected from the group consisting of: dimethylolformic acid, dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutyric acid, dimethylolvalerate, dimethylolhexanoic acid, dimethylolheptanoic acid, dimethylolnonanoic acid, dimethyloldecanoic acid, dimethylollauric acid, dimethylpalmitic acid, dimethylolstearic acid, dimethylolcyclohexanecarboxylic acid, dimethylolbenzoic acid, and any combination thereof.

[0032] According to another embodiment of this disclosure, the catalyst of component (F) is selected from the group consisting of organotin, organobismuth, tertiary amines, morpholine derivatives, piperazine derivatives, and combinations thereof.

[0033] According to another embodiment of this disclosure, the content of component (A) is from 5% to 50% by weight based on the total weight of components (A), (B), (E), and (F). According to another embodiment of this disclosure, the content of component (B) is from 25% to 85% by weight based on the total weight of components (A), (B), (E), and (F). According to another embodiment of this disclosure, the content of component (E) is from 1% to 10% by weight based on the total weight of components (A), (B), (E), and (F). According to another embodiment of this disclosure, the content of component (F) is at most 1% by weight based on the total weight of components (A), (B), (E), and (F). According to another embodiment of this disclosure, the molar ratio between component (G) and component (E) is from 1:2 to 2:1. According to another embodiment of this disclosure, the weight ratio between component (D) and the total weight of components (A), (B), (E), and (F) is from 1:100 to 3:10. According to another embodiment of this disclosure, the weight ratio between component (C) and the total weight of components (A), (B), (E) and (F) is 1:50 to 1:10.

[0034] In a second aspect of this disclosure, a synthetic leather article is provided, comprising, from top to bottom: a polyurethane skin film obtained from an internally emulsified polyurethane dispersion of this disclosure; an intermediate foam layer; and a bottom fabric layer.

[0035] In a second aspect, this disclosure provides a method for preparing an internally emulsified polyurethane dispersion, comprising:

[0036] (i) React component (A) with components (B) and (E) in the presence of component (F) to form a PUD prepolymer;

[0037] (ii) Neutralize the PUD prepolymer with component (G); and

[0038] (iii) The neutralized PUD prepolymer is combined with components (C), (D) and (H) to form an internally emulsified polyurethane dispersion.

[0039] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and not intended to limit the invention as claimed. Attached Figure Description

[0040] Figure 1 This is a schematic cross-sectional view of one embodiment of the synthetic leather laminate structure described in this article. Detailed Implementation

[0041] 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 this invention pertains. Furthermore, all publications, patent applications, patents, and other references mentioned herein are incorporated herein by reference.

[0042] As disclosed herein, “and / or” means “and, or as an alternative”. Unless otherwise specified, all ranges include end values.

[0043] In one embodiment of this disclosure, the polyurethane dispersion is prepared via a first step: reacting components (A), (B), and (E) in the presence of component (F) to form a PUD prepolymer; a second step: neutralizing the PUD prepolymer with component (G); and a third step: combining the neutralized PUD prepolymer with components (C), (D), and (H) to form an internally emulsified polyurethane dispersion. As used herein, the term "PUD prepolymer" refers to a prepolymer of PU that has not been blended with components (C), (D), and (H) in the third step.

[0044] As used herein, the term "internal emulsification" or "internal emulsification" refers to a mechanism in which the emulsifying function is substantially or entirely contributed by component (E) which is covalently integrated within the polyurethane backbone. Specifically, in the first step described above, the isocyanate reactive groups of component (B) and the hydroxyl groups of component (E) react with the isocyanate groups of component (A) to form the polyurethane backbone, wherein carboxylic acid groups exist as side groups covalently attached to the copolymer units derived from component (E), thus exhibiting an "internal emulsification" effect on the polyurethane dispersion. The carboxylic acid side groups can be in the form of carboxylic acid groups, anionic carboxylate groups, nonionic carboxylate groups, or combinations thereof. For example, the pH of the polyurethane dispersion can be appropriately adjusted as needed so that a portion of the carboxylic acid side groups are in the form of carboxylic acid groups, while the remainder can be anionic carboxylate groups or nonionic carboxylate groups.

[0045] As used herein, the term "externally emulsified" or "externally emulsified" refers to a different mechanism by which the components exhibiting emulsifying function are not covalently attached to the polyurethane backbone (i.e., external emulsifiers / surfactants). According to a preferred embodiment of this disclosure, the polyurethane dispersion of this disclosure is completely internally emulsified. In other words, no external emulsifiers / surfactants are added before, during, and after the formation of the polyurethane dispersion.

[0046] According to one embodiment of this disclosure, the polyurethane formed in the first step contains at least one free isocyanate group, such as one or two free isocyanate groups, in the main chain of each polymer, and is referred to as a "PUD prepolymer," which can be further reacted with components (C) and (D) in a third step to produce the polyurethane dispersion of this disclosure. According to a preferred embodiment of this disclosure, the PUD prepolymer formed in the first stage has an isocyanate group content (NCO%) of 1% to 20% by weight, such as 3% to 15% by weight, preferably greater than 3.0% by weight, more preferably greater than 4% by weight, such as about 4.5% to 5.0% by weight.

[0047] In the third step, the free isocyanate groups contained in the PUD prepolymer react with the amine groups of components (C) and (D) to elongate the PU backbone and form the polyurethane dispersion of this disclosure.

[0048] According to one embodiment of this disclosure, no hazardous and / or flammable solvents such as dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), acetone, etc., are used in the preparation of the PUD. According to another embodiment of this disclosure, the PUD contains no hazardous and / or flammable solvents. According to yet another embodiment of this disclosure, the PUD may optionally contain a green organic solvent, i.e., an environmentally friendly organic solvent, in an amount of 0-15% by weight, or 2% to 12% by weight, or 3% to 10% by weight based on the total weight of the PUD.

[0049] The components used to prepare the polyurethane dispersions are described in detail in the following paragraphs.

[0050] Component (A)

[0051] In various embodiments, the isocyanate compound of component (A) has an average functionality of at least about 2.0, such as about 2 to 10, or about 2 to about 8, or about 2 to about 6. In some embodiments, component (A) comprises a polyisocyanate compound containing at least two isocyanate groups. In another embodiment of this disclosure, the polyisocyanate compound comprises an aromatic, aliphatic, alicyclic, or aryliphatic polyisocyanate having two or more isocyanate groups. In one embodiment of this disclosure, the polyisocyanate compound is selected from the group consisting of C4-C... 12 Aliphatic polyisocyanates, C6-C containing at least two isocyanate groups 15 Alicyclic or aromatic polyisocyanates, C7-C containing at least two isocyanate groups 15Aliphatic polyisocyanates, and combinations thereof. In another embodiment of this disclosure, the polyisocyanate compound comprises various isomers of m-phenylene diisocyanate, 2,4-toluene diisocyanate and / or 2,6-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, naphthyl-1,5-diisocyanate, isophorone diisocyanate (IPDI), or mixtures thereof.

[0052] According to another embodiment of this disclosure, the isocyanate component can be a modified polyfunctional isocyanate, i.e., a product obtained by the chemical reaction of the above-described isocyanate compounds. Examples are polyisocyanates containing esters, ureas, biurets, isocyanurates, urethanes, and preferably carbodiimides and / or ureaketimides, such as 4,4'-carbodiimide-modified MDI products. Liquid polyisocyanates containing carbodiimide groups, ureaketimide groups, and / or isocyanurate rings can also be used, with an isocyanate group (NCO) content of 10 to 40 wt%, such as 20 to 35 wt%.

[0053] Alternatively or additionally, the polyisocyanate compound may include an isocyanate prepolymer having a functionality in the range of 2 to 10, such as 2 to 8, or 2 to 6. The isocyanate prepolymer may be obtained by reacting one or more of the above-described monomeric isocyanate compounds with one or more isocyanate reactive compounds selected from the group consisting of: ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,4-butynediol, 1,5-pentanediol, neopentanediol, bis(hydroxymethyl)cyclohexane such as 1,4-bis(hydroxymethyl)cyclohexane, 2-methylpropane-1,3-diol, methylpentanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, dibutylene glycol, and polybutanediol. Suitable prepolymers for use as component (A) are those with an NCO group content of 2 to 40 wt%, such as 4 to 30 wt%. These isocyanate prepolymers can be prepared by reacting diisocyanate compounds and / or polyisocyanate compounds with materials including lower molecular weight diols and triols. A separate example is an alicyclic or aromatic polyisocyanate containing urethane groups, preferably with an NCO content of 2 to 40 wt%, such as 5 to 35 wt%, obtained by reacting diisocyanates and / or polyisocyanates with, for example, lower molecular weight diols, triols, olefin glycols, olefin dioxide, or polyoxyolefin glycols with a molecular weight up to about 800. These polyols can be used alone or in the form of mixtures of olefin dioxide and / or polyoxyolefin glycols. For example, diethylene glycol, dipropylene glycol, polyethylene glycol, ethylene glycol, propylene glycol, butanediol, polyoxypropylene glycol, and polyoxypropylene-polyoxyethylene glycol can be used. Polyester polyols, as well as alkane diols such as butanediol, can also be used. Other useful diols include dihydroxyethyl- or dihydroxypropyl-bisphenol A, cyclohexanediol, and dihydroxyethylhydroquinone.

[0054] Typically, the amount of component (A) can vary based on the actual requirements of the synthetic leather product. For example, as an exemplary embodiment, the content of component (A) is based on the total weight of all components used to prepare the intermediate PU polymer in the first stage, i.e., based on the total weight of components (A), (B), (E), and (F), it can be from about 5% to about 50% by weight, such as from about 10% to about 40% by weight, or from about 15% to about 30% by weight, or from about 20% to about 25% by weight.

[0055] Component (B)

[0056] In various embodiments of this disclosure, component (B) comprises one or more polyols selected from the group consisting of: aliphatic polyols containing at least two hydroxyl groups, alicyclic or aromatic polyols containing at least two hydroxyl groups, arylaliphatic polyols containing at least two hydroxyl groups, polyether polyols, polyester polyols, vegetable oils having at least two hydroxyl groups, and mixtures thereof. For example, the polyol may be selected from the group consisting of: C2-C16 aliphatic polyols containing at least two hydroxyl groups, C6-C15 alicyclic or aromatic polyols containing at least two hydroxyl groups, C7-C15 arylaliphatic polyols containing at least two hydroxyl groups, polyester polyols containing at least two hydroxyl groups and having a molecular weight of 100 to 5,000, polyether polyols containing at least two hydroxyl groups and having a molecular weight of 1,500 to 12,000, and combinations thereof.

[0057] In one embodiment of this disclosure, component (B) comprises a mixture of two or more different polyols, such as a mixture of two or more polyether polyols, a mixture of two or more polyester polyols, a mixture of at least one polyether polyol and at least one polyester polyol, a mixture of two or more vegetable oils having at least two hydroxyl groups, or a mixture of polyether polyols and polycarbonate polyols.

[0058] In an alternative embodiment, component (B) is a polyether polyol with a functionality (average number of isocyanate reactive groups, particularly hydroxyl groups, in the polyol molecule) of 2.0 to 3.0 and a weight-average molecular weight (Mw) of 1,500 g / mol to 12,000 g / mol, such as 2,000 g / mol to 8,000 g / mol, or 2,000 g / mol to 6,000 g / mol. According to one embodiment of this disclosure, the polyether polyol is selected from the group consisting of polytetrahydrofuran, poly(propylene glycol), and copolymers of ethylene oxide and propylene oxide having primary and secondary hydroxyl terminal groups. According to another embodiment of this disclosure, the polyether polyol is polytetrahydrofuran (PTMEG) with a hydroxyl functionality of 2 and a weight-average molecular weight (Mw) of about 2,000.

[0059] Polyether polyols are typically prepared by polymerizing one or more epoxides selected from propylene oxide (PO), ethylene oxide (EO), butane oxide, tetrahydrofuran, and mixtures thereof with a suitable initiator molecule in the presence of a catalyst. Typical initiator molecules include compounds having at least two, preferably four to eight, hydroxyl groups or two or more primary amine groups in the molecule. Suitable initiator molecules are selected, for example, from aniline, EDA, TDA, MDA, and PMDA, more preferably from TDA and PMDA, and most preferably from TDA. When using TDA, all isomers can be used alone or in any desired mixture. For example, mixtures of 2,4-TDA, 2,6-TDA, 2,4-TDA, and 2,6-TDA, 2,3-TDA, 3,4-TDA, 3,4-TDA, and 2,3-TDA, as well as mixtures of all the above isomers, can be used. Initiator molecules having at least two, and preferably two to eight, hydroxyl groups in the molecule, preferably include trimethylolpropane, glycerol, pentaerythritol, castor oil, sugar compounds such as glucose, sorbitol, mannitol and sucrose, polyphenols, oligomerization condensations of phenolic resins such as phenol and formaldehyde, and Mannich condensates of phenol, formaldehyde and dialkylolamines, as well as melamine. Catalysts for preparing polyether polyols may include basic catalysts for anionic polymerization, such as potassium hydroxide, or Lewis acid catalysts for cationic polymerization, such as boron trifluoride. Suitable polymerization catalysts may include potassium hydroxide, cesium hydroxide, boron trifluoride, or dicyanide complex (DMC) catalysts, such as zinc hexacyanocobaltate or quaternary phosphazeneonium compounds. In a preferred embodiment of this disclosure, the polyether polyol includes (methoxy) polyethylene glycol (MPEG), polyethylene glycol (PEG), poly(propylene glycol), or a copolymer of ethylene oxide and propylene oxide having primary hydroxyl end-capping groups and secondary hydroxyl end-capping groups.

[0060] Typically, the content of component (B) used herein is based on the total weight of all components used to prepare the intermediate PU polymer in the first stage, i.e., based on the total weight of components (A), (B), (E) and (F), which can be in the range of about 25 wt% to about 85 wt%, or about 45 wt% to about 85 wt%, or about 55 wt% to about 76 wt%, or about 65 wt% to about 75 wt%.

[0061] Component (C)

[0062] The hydrophilic aminosiloxane compound of component (C) is a compound comprising a silicon-oxygen backbone attached to nitrogen-containing side chains and hydrophilic side chains. The molecular structure of the hydrophilic aminosiloxane compound can be represented by formula I:

[0063]

[0064] 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). a -O-CH2-CH=CH2;

[0065] R1 is -(CH2) m NH2 or -(CH2) s -NH-(CH2) t NH2;

[0066] R2 is -CH2CH2CH2O(CH2CH2O) n H; and

[0067] Each of R3, R4, R5, R6, and R7 is independently selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, cyclohexyl, phenyl, and tolyl;

[0068] Where a is an integer from 1 to 10, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10; x is an integer from 20 to 500, such as 20 to 200, or 50 to 150, or 80 to 120, or 90 to 100; y is an integer from 1 to 20, or from 1 to 10, such as 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 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20; The integers are 1, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20; m is an integer from 1 to 10, or from 1 to 5, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10; s is an integer from 1 to 10, or from 1 to 5, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10; t is an integer from 1 to 10, or from 1 to 5, such as 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10; and n is an integer from 5 to 30, such as 5 to 20, or 10 to 15.

[0069] Without being limited to any particular theory, the amine group in R1 and the hydroxyl group in R2 can react with the remaining isocyanate groups in the intermediate PU polymer to produce a polyurethane that includes the aforementioned siloxane structure in the polyurethane backbone, thereby significantly improving the performance properties of the resulting PU skin film, such as anti-adhesion.

[0070] According to a preferred embodiment of this disclosure, the hydrophilic aminosiloxane compound has a structure represented by formula Ia:

[0071]

[0072] R, R1, R2, x, y, and z are as described above.

[0073] Typically, the content of the hydrophilic aminosiloxane compound used herein is based on the total weight of all components used in the first stage to prepare the intermediate PU polymer, i.e., based on the total weight of components (A), (B), (E), and (F) being 2 wt% to 10 wt%, or 2 wt% to 8 wt%, or 3 wt% to 7 wt%, or 4 wt% to 5 wt%. It can be seen that the content of the hydrophilic aminosiloxane compound is calculated with the total amount of the intermediate PU polymer being 100 wt% as an additional amount. According to one embodiment of this disclosure, the hydrophilic aminosiloxane compound is first dissolved / dispersed in water by mixing to obtain an aqueous solution, and then degassed; therefore, the aforementioned content of the hydrophilic aminosiloxane compound is calculated based on the amount of siloxane solute / dispersed phase rather than the amount of solution / dispersion.

[0074] The hydrophilic aminosiloxane compound is added during the second stage and is not incorporated into the PU polymer backbone during the synthesis of the intermediate PU polymer. This is because if the siloxane is added during the first stage, a certain degree of polymer gelation will form.

[0075] Component (D)

[0076] Component (D) is a polyetheramine compound represented by formula II:

[0077]

[0078] Each of R8 and R9 is independently selected from the group consisting of: hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, cyclohexyl, phenyl, tolyl, and combinations thereof, and q is an integer from 2 to 20. According to one embodiment of this disclosure, q is an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20.

[0079] According to another embodiment of this disclosure, each of R8 and R9 is independently selected from the group consisting of hydrogen, methyl, and combinations thereof. As used herein, the expression "combinations thereof" means that a portion of R8 / R9 is hydrogen, while the remainder of R8 / R9 may be methyl. Examples of polyetheramines may include Jeffamine D-230, Jeffamine D-400, Jeffamine ED-600, Jeffamine D-2000, and any combination thereof.

[0080] Typically, the content of the polyetheramine compound used herein is based on the total weight of all components used to prepare the PUD prepolymer in the first stage, i.e., based on the total weight of components (A), (B), (E), and (F) being 1 wt% to 30 wt%, or 5 wt% to 25 wt%, or 10 wt% to 22 wt%, or 11 wt% to 22 wt%. It can be seen that the content of the hydrophilic aminosiloxane compound is calculated as an additional amount of 100 wt% of the total amount of the PUD prepolymer. According to one embodiment of this disclosure, the polyetheramine compound is blended with the neutralized PUD prepolymer in the form of a solution (such as an aqueous solution), therefore the content of the polyetheramine compound is calculated based on the amount of polyetheramine solute rather than the amount of solution. According to one embodiment of this disclosure, the molar ratio between the polyetheramine compound and the PUD prepolymer formed in the first stage is 1:10 to 1:1, such as 1:5 to 1:1, preferably 4:5 to 1:1, more preferably 9:10.

[0081] According to one embodiment of this disclosure, the polyetheramine compound has an amino functionality of about 2.0 to 3.0. According to another embodiment of this disclosure, the polyetheramine compound has a weight-average molecular weight of 200-2000 g / mol, or 200 g / mol to 1000 g / mol, but preferably less than 600 g / mol, more preferably 200 g / mol to 500 g / mol or 200 g / mol to 400 g / mol.

[0082] According to one embodiment of this disclosure, no additional extending agent other than components (C) and (D) is used. According to another embodiment of this disclosure, the preparation of the PUD prepolymer and / or PUD may further include additional extending agents other than components (C) and (D), and examples of such additional extending agents may include, for example, propylenediamine (PDa), aminoethylethanolamine (AEEa), hexamethylenediamine (HDa), and any combination thereof. According to one embodiment of this disclosure, the weight ratio between component (D) and the "extending agent" may be from 10:1 to 2:1, such as from 8:1 to 4:1, or from 6:1 to 5:1.

[0083] Component (E)

[0084] Component (E) is a C2-C having at least two hydroxyl groups. 20Carboxylic acid compounds, and examples of said component (E) are selected from the group consisting of: dimethylolformic acid, dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutyric acid, dimethylolvalerate, dimethylolhexanoic acid, dimethylolheptanoic acid, dimethylolnonanoic acid, dimethyloldecanoic acid, dimethylollauric acid, dimethylolpalmitic acid, dimethylolstearic acid, dimethylolcyclohexanecarboxylic acid, dimethylolbenzoic acid, dihydroxyglutaric acid, tartaric acid, and any combination thereof. The content of component (C) used herein is based on the total weight of all components used in the preparation of the intermediate PU polymer in the first stage, i.e., based on the total weight of components (A), (B), (E), and (F) of 1% to 10% by weight, or 2% to 5% by weight, or 3% to 4% by weight.

[0085] Component (F)

[0086] Catalysts can include any substance that can promote the reaction between isocyanate groups and isocyanate reactive groups. Without being theoretically limited, catalysts can include, for example, glycinate salts; tertiary amines; tertiary phosphines, such as trialkylphosphine and dialkylbenzylphosphine; morpholine derivatives; piperazine derivatives; chelates of various metals, such as those obtainable from acetylacetone, benzoylacetone, trifluoroacetylacetone, ethyl acetoacetate, etc., with metals such as Be, Mg, Zn, Cd, Pd, Ti, Zr, Sn, As, Bi, Cr, Mo, Mn, Fe, Co, and Ni; acidic metal salts of strong acids, such as ferric chloride and tin chloride; and salts of organic acids with various metals, such as alkali metals and alkaline earth metals. Al, Sn, Pb, Mn, Co, Ni, and Cu; organotin compounds, such as tin(II) salts of organic carboxylic acids, such as tin(II) diacetate, tin(II) dioctanoate, tin(II) diethylhexanoate, and tin(II) dilaurate, and dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate, and dioctyltin diacetate; bismuth salts of organic carboxylic acids, such as bismuth octanoate; organometallic derivatives of trivalent and pentavalent As, Sb, and Bi, and carbonyl metals of iron and cobalt; or mixtures thereof.

[0087] Tertiary amine catalysts include organic compounds containing at least one tertiary nitrogen atom and capable of catalyzing hydroxyl / isocyanate reactions. By way of example, and not limitation, tertiary amine, morpholine derivative, and piperazine derivative catalysts may include triethylenediamine, tetramethylethylenediamine, pentamethyldiethylenetriamine, bis(2-dimethylaminoethyl) ether, triethylamine, tripropylamine, tributylamine, tripentylamine, pyridine, quinoline, dimethylpiperazine, piperazine, N-ethylmorpholine, 2-methylpropanediamine, methyltriethylenediamine, 2,4,6-tris(dimethylamino-methyl)phenol, N,N',N”-tris(dimethylamino-propyl)hexahydrotriazine, or mixtures thereof.

[0088] The catalyst content used in this article is based on the total weight of all components used to prepare the intermediate PU polymer in the first stage, i.e., based on the total weight of components (A), (B), (E) and (F) at most 1.0 wt%, or at most 0.5 wt%, or at most 0.1 wt%, or at most 0.05 wt%.

[0089] Component (G)

[0090] The neutralizing agent for component (G) may include organic bases such as trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexylamine, triethanolamine, triethanolamine, and any combination thereof. The molar ratio between component (G) and component (E) is 1:2 to 2:1, such as 7:10 to 1:1.

[0091] Component (H)

[0092] Water, such as deionized water, is added in the second stage. The water content can be suitably selected such that the polyurethane dispersion of this disclosure has a high solids loading of polyurethane particles, such as at least 45% by weight, or more than 45% by weight, or more than 47% by weight, or more than 48% by weight, or more than 49% by weight, or at least 50% by weight, or more than 50% by weight and at most 70% by weight, or at most 65% by weight, or at most 60% by weight, or at most 55% by weight.

[0093] The polyurethane dispersion of this disclosure can be heated and dried to form a skin film that exhibits excellent improved anti-sticking, anti-wrinkle and color fastness, while maintaining good mechanical properties of PUD film.

[0094] The aqueous polyurethane dispersion may optionally contain a rheology modifier, such as a thickener that improves the dispersibility and stability of the dispersion. Any suitable rheology modifier can be used, such as those known in the art. Preferably, the rheology modifier is one that does not cause the dispersion to become unstable. More preferably, the rheology modifier is an unionized, water-soluble thickener. Examples of available 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), and associative thickeners (e.g., hydrophobically modified ethylene oxide-based urethane block copolymers). Preferably, the rheology modifier is methylcellulose ether. The amount of thickener is at least about 0.2% by weight to about 5% by weight of the total weight of the aqueous polyurethane dispersion, preferably about 0.5% by weight to about 2% by weight. According to another embodiment of this disclosure, no thickener / rheology modifier is added to the polyurethane dispersion.

[0095] Typically, aqueous polyurethane dispersions have a viscosity of at least about 10 cp to at most about 10,000 cp, preferably at least about 20 cp to at most about 5,000 cp, and more preferably at least about 30 cp to at most about 3,000 cp.

[0096] In one embodiment of this disclosure, the dispersion of PU particles in an aqueous polyurethane dispersion can be promoted by an internal emulsifier and high shear stirring action, wherein the shear force and stirring speed can be appropriately adjusted based on specific requirements.

[0097] According to one embodiment of this disclosure, the aqueous polyurethane dispersion may also contain one or more pigments, dyes, and / or colorants, all of which are generally referred to herein as “masterbatches.” For example, masterbatches may be added to impart a desired color to a transparent or translucent film. Examples of pigments, dyes, and / or colorants may include iron oxide, titanium oxide, carbon black, and mixtures thereof. The amount of pigments, dyes, and / or colorants may be from 0.1% to 15% by weight, preferably 0.5-10% by weight, and more preferably 1% to 5% by weight, based on the total weight of the aqueous polyurethane dispersion. Additives such as crosslinking agents (e.g., aziridine), slip agents, fast-drying agents (e.g., propylene glycol), wetting agents, and defoamers (e.g., silicone resins) are additional components in the PUD formulation for synthetic leather applications. Hazardous and flammable solvents such as dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), and acetone are not used in the PUD preparation process. Green solvents such as dipropylene glycol dimethyl ether (DMM) may be optionally used to reduce the viscosity of the PUD in the first and / or stage.

[0098] Laminated synthetic leather products

[0099] Figure 1 This is a schematic cross-sectional view of one embodiment of the synthetic leather article described herein. In one embodiment of this disclosure, the synthetic leather article comprises, from top to bottom, a top layer of film formed from the polyurethane dispersion of this disclosure, a foam layer, and a bottom fabric layer (e.g., a woven fabric). Note that the leather article is not necessarily shown to scale, and the dimensions of one or more layers may be enlarged to clearly show its construction.

[0100] The foam layer may be formed from 1K PU foam, 2K PU foam, mechanically foamed PUD foam, preferably non-solvent PU foam, and includes a continuous PU matrix defining a plurality of pores and / or cells therein.

[0101] According to one embodiment of this disclosure, a laminate can be formed by sequentially applying a PU top layer, an intermediate foam layer, and a bottom fabric layer onto a release layer. Suitable release layers are generally referred to in the prior art as "release paper." Examples of suitable release layers include foils of metal, plastic, or paper. In a preferred embodiment of this disclosure, the release layer is a paper layer optionally coated with a plastic film. Preferably, the paper layer disclosed herein is coated with a polyolefin, more preferably polypropylene. Alternatively, the paper layer is preferably coated with silicone. In another embodiment, the release layer used herein is a PET layer optionally coated with a plastic film. Preferably, the PET layer may be coated with a polyolefin, more preferably polypropylene. Alternatively, the PET layer is preferably coated with silicone. Examples of suitable release layers are commercially available. The release layer used in this disclosure may have a flat, embossed, or patterned surface, such that corresponding or complementary surface profiles can be formed on the outermost surface of the synthetic leather article. Preferably, the release layer is textured in the pattern of leather grain to impart good tactile properties to the synthetic leather article comparable to high-grade natural leather. The release layer typically 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.

[0102] The material and thickness of the release layer can be adjusted appropriately, as long as the release layer can withstand the chemical reactions, machining and heat treatments experienced during the manufacturing process, and can be easily peeled off from the resulting synthetic leather without causing delamination between the epidermal film and the intermediate foam layer.

[0103] The PU outer film and intermediate foam layer may independently and optionally contain any additional auxiliaries and / or additives for a specific purpose.

[0104] In one embodiment of this disclosure, one or more of the additives and / or auxiliaries may be selected from the group consisting of: fillers, cell regulators, stripping agents, colorants / pigments, surfactants, hand feel agents, matting agents, thickeners, crosslinking agents, and stabilizers.

[0105] In one embodiment of this disclosure, the bottom fabric layer has a thickness ranging from 0.01 mm to 50 mm, preferably from 0.05 mm to 10 mm, and more particularly from 0.1 mm to 5 mm. The bottom fabric layer may include one or more of the following: fabrics (preferably woven or nonwoven), impregnated fabrics, knitted fabrics, braided fabrics, or microfibers; foils of metal or plastic, such as rubber, PVC, or polyamide; and leather, preferably split leather.

[0106] The bottom fabric layer can be made of woven or nonwoven textiles. Preferably, the textile is a nonwoven textile. The textile can be made by any suitable method, such as those well known in the art. The textile can be made from any suitable fibrous material. Suitable fibrous materials include, but are not limited to, synthetic fibrous materials and natural or semi-synthetic fibrous materials, as well as mixtures or blends thereof. Examples of synthetic fibrous materials include polyesters, polyamides, acrylics, polyolefins, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, and blends or mixtures thereof. Examples of natural or semi-synthetic fibrous materials include cotton, wool, and hemp.

[0107] Manufacturing technology

[0108] The polyurethane dispersion disclosed herein can be applied using conventional coating techniques such as spraying, blade coating, molding, casting, etc.

[0109] Before applying the next layer, the epidermal film can be partially or completely dried. Preferably, the epidermal film is completely dried to minimize the moisture entrained therein, and then the next layer is applied on top of it. In an alternative embodiment of this application, only a portion of the moisture is removed from the epidermal film on the peeling layer, and then the epidermal film is completely dried together with the foam layer applied thereon.

[0110] According to one embodiment, the intermediate foam layer can be formed by: blending a mechanically foaming PU material (preferably an aqueous dispersion of PU, such as SCISKY KT-650 available from Scisky) with one or more processing aids under mechanical stirring, these processing aids being selected from the group consisting of surfactants, emulsifiers, thickeners, foaming agents, catalysts, dispersants, dispersing aids, foam stabilizers, and fillers; applying the blend onto a skin film; and heating the wet foam layer in an oven at a temperature of, for example, 70°C to 150°C, preferably 90°C to 130°C, for a short duration of 10 seconds to 20 minutes, preferably 30 seconds to 15 minutes, and more preferably 1 minute to 10 minutes. After the first foam layer dries, another foam layer with a similar formulation and higher viscosity is coated onto the first foam layer. Then, without drying, the bottom fabric layer is applied to the foam layer using a pressure roller, followed by post-curing at a higher temperature, such as 100°C to 160°C, preferably 110°C to 150°C, for 3 to 20 minutes, preferably 3 to 15 minutes, and more preferably 4 to 10 minutes for a longer duration. This two-step curing process aims to ensure high adhesive strength between the pre-cured foam layer and the fabric layer.

[0111] According to one embodiment of this disclosure, the release layer is removed after the foam layer and the surface layer have fully cured. The release layer can be peeled off using any common technique.

[0112] According to one embodiment of this disclosure, after removing the peeling layer, a top finishing layer can be applied to the surface of the synthetic leather (i.e., the outermost surface of the epidermal film) and dried to form a protective film layer. The presence of the finishing layer can further increase the abrasion resistance of the multilayer synthetic leather. The protective film layer can be formed using any suitable raw materials and techniques. The finishing layer may optionally contain additives such as wetting agents, crosslinking agents, binders, matting agents, hand feel modifiers, pigments and / or colorants, thickeners, or other additives for the epidermal film. The synthetic leather disclosed herein may also include one or more optional additional layers, such as a colored layer between the epidermal film and the finishing layer. Other suitable optional additional layers may be selected from water-repellent layers, UV protective layers, and tactile (touch / feel) modifying layers. The process of the present invention can be carried out continuously or in batches.

[0113] The multi-layered synthetic leather disclosed herein can be cut or otherwise shaped to have a form suitable for any desired purpose, such as shoemaking. Depending on the intended application, the synthetic leather can undergo further processing or post-treatment similar to natural leather, such as by brushing, filling, milling, or ironing. If desired, the synthetic leather (like natural leather) can be finished with conventional finishing compositions. This provides further possibilities for controlling its characteristics. The multi-layered structure disclosed herein can be used in a variety of applications particularly suitable for use as synthetic leather, such as footwear, handbags, belts, wallets, clothing, furniture upholstery, automotive interiors, and gloves. This multi-layered structure is particularly suitable for automotive applications.

[0114] Example

[0115] Some embodiments of the invention will now be described in the following examples, wherein all parts and percentages are by weight unless otherwise stated.

[0116] Table 1 below lists information about the raw materials used in the example:

[0117] Table 1. Raw materials used in the following examples

[0118]

[0119] In the following Examples (IE) 1-3 and Comparative Examples (CE) 1-8, polyurethane dispersions for internal emulsification of epidermal membranes were prepared.

[0120] Example 1

[0121] In the first stage, PUD prepolymers were prepared using the following procedure. I72g of PTMEG-2000 and 3g of DMBA were placed in a 500ml three-necked flask and dehydrated at 115°C and 76mmHg pressure for one hour. The dehydrated polyol mixture was then allowed to cool naturally to 70°C-75°C. 25g of IPDI was added to the dehydrated polyol mixture at the same temperature, under nitrogen (N2) protection and mechanical stirring. Then, 0.05g of catalyst DABCO MB20 was added to the flask. The reaction was continued at 70°C-75°C for one hour, then heated to 80-85°C and continued at this temperature for 2.5 hours to obtain PUD prepolymer I, which has a theoretical NCO% of 4.7% by weight.

[0122] In the second stage, the PUD was prepared using the following procedure: 100 g of PUD prepolymer I was added to a 500 ml three-necked flask, cooled to approximately 60°C, and 1.74 g of TEA was added for neutralization. 5 g of DMM was added and the mixture was stirred further for 15 min. The mixture was transferred to a 500 ml plastic cup, 75.9 g of an ice / water blend was added, and the mixture was stirred for 8 min at approximately 3000 rpm using a Cowles mixer to form an emulsion, after which the stirring speed was reduced to approximately 2000 rpm. 29 g of Jeffamine D-230 (40 wt% aqueous solution) and 25 g of OFX-7700 aminosiloxane (20 wt% aqueous solution) were added to the emulsion. Finally, the polyurethane dispersion was obtained after filtration and stored in a capped plastic container. The PUD prepared in Example 1 had a solids content of 50 wt%.

[0123] Example 2

[0124] In the first stage, PUD prepolymer I is prepared according to the corresponding procedure of claim 1.

[0125] In the second stage, the PUD was prepared using the following procedure: 100 g of PUD prepolymer I was added to a 500 ml three-necked flask, cooled to approximately 60°C, and 1.74 g of TEA was added for neutralization. 5 g of DMM was added and the mixture was stirred further for 15 min. The mixture was transferred to a 500 ml plastic cup, 70.9 g of an ice / water blend was added, and the mixture was stirred for 8 min at approximately 3000 rpm using a Cowles mixer to form an emulsion, after which the stirring speed was reduced to approximately 2000 rpm. 54 g of Jeffamine D-400 (40 wt% aqueous solution) and 25 g of OFX-7700 aminosiloxane (20 wt% aqueous solution) were added to the emulsion. Finally, after filtration, a polyurethane dispersion was obtained and stored in a capped plastic container. The PUD prepared in Example 2 had a solids content of 50 wt%.

[0126] Example 3

[0127] In the first stage, the PUD prepolymer is prepared according to the corresponding procedure of claim 1.

[0128] In the second stage, the PUD was prepared using the following procedure: 100 g of PUD prepolymer I was added to a 500 ml three-necked flask, cooled to approximately 60°C, and 1.74 g of TEA was added for neutralization. 5 g of DMM was added and the mixture was stirred further for 15 min. The mixture was transferred to a 500 ml plastic cup, 70.75 g of an ice / water blend was added, and the mixture was stirred for 8 min at approximately 3000 rpm using a Cowles mixer to form an emulsion, after which the stirring speed was reduced to approximately 2000 rpm. 27 g of Jeffamine D-400 (40 wt% aqueous solution), 25 g of OFX-7700 aminosiloxane (20 wt% aqueous solution), and 9.3 g of PDA (20 wt% aqueous solution) were added to the emulsion. Finally, after filtration, a polyurethane dispersion was obtained and stored in a capped plastic container. The PUD prepared in Example 3 had a solids content of 50 wt%.

[0129] Comparative Examples 1-6

[0130] Examples 1-4 and 6 were compared in essentially the same procedure as in Example 1, except that the formulations were modified based on Table 2 below, where the amounts of all components are expressed in grams.

[0131] Comparative Example 5 was carried out using the following procedure: In the first stage, 76 g of PTMEG-2000 and 3 g of DMBA were placed in a 500 ml three-necked flask and dehydrated at 115 °C and 76 mmHg for one hour. The dehydrated polyol mixture was then allowed to cool naturally to a temperature of 70 °C to 75 °C. 21 g of IPDI was added to the dehydrated polyol mixture at the same temperature under nitrogen (N2) protection and mechanical stirring. Then, 0.05 g of catalyst DABCO MB20 was added to the flask. The reaction was continued at 70 °C to 75 °C for one hour, then heated to 80-85 °C and continued at this temperature for 2.5 hours to obtain PUD prepolymer II, which has a theoretical NCO% of 3.0 wt%.

[0132] In the second stage, the PUD was prepared using the following procedure: 100 g of PUD prepolymer II was added to a 500 ml three-necked flask, cooled to approximately 60°C, and 1.74 g of TEA was added for neutralization. 10 g of DMM was added and the mixture was stirred further for 15 min. The mixture was transferred to a 500 ml plastic cup, 93.8 g of ice / water blend was added, and the mixture was stirred for 8 min at approximately 3000 rpm using a Cowles mixer to form an emulsion, after which the stirring speed was reduced to approximately 2000 rpm. 11.9 g of PDA (20 wt% aqueous solution) and 25 g of OFX-7700 aminosiloxane (20 wt% aqueous solution) were added to the emulsion together. Finally, after filtration, the polyurethane dispersion was obtained and stored in a capped plastic container. The PUD prepared in Comparative Example 5 had a solids content of 45 wt%.

[0133] Table 2: Formulations of the Embodiments (IE) and Comparative Embodiments (CE) of the present invention

[0134]

[0135]

[0136] Preparation of PUD epidermal film

[0137] Weigh 22.5 g of the polyurethane dispersion prepared in each of Examples 1-3 and Comparative Examples 1-8 of the present invention and dilute with an equal volume of deionized water. Transfer the diluted PUD to a vacuum oven and degas for ~10 minutes. Then pour the degassed PUD into a plastic surface petri dish. Transfer the dish filled with PUD to an oven and heat at 54°C for 24 hours. After that, peel the film off the dish, invert it, and continue drying for another 24 hours. Cool the film to room temperature for testing.

[0138] Processing and manufacturing of synthetic leather products

[0139] The aqueous polyurethane dispersions prepared in each of Examples 1-3 and Comparative Examples 1-6 of the present invention were mixed at high speed (3000 rpm) for several minutes with the color masterbatch, crosslinking agent, thickener, slip agent, and defoamer as shown in Table 3. The prepared PUD was coated onto release paper to a wet film thickness of 100 μm. The coated release paper was dried in an oven at 90°C for 2 min, and then at 110°C for 8 min. The release paper with the dried PU surface layer was removed from the oven and cooled to ambient temperature. A PUD foam layer with a foaming ratio of 250% (see Table 4) obtained by mechanical foaming was coated onto the dried PU surface film on the release paper to a wet film thickness of 400 μm. The release paper with the PU surface film and the coated foam layer was transferred to an oven at 130°C and pre-cured for 10 min. Then, the PU foam layer was coated again onto the coated release paper using the same doctor blade, and the fabric was carefully placed on the wet foam layer and pressed twice with a 3.5 kg roller. The leather sample was placed in a 130°C oven and post-cured for 10 minutes, then removed and cooled.

[0140] Table 3. Surface formulation

[0141] PUD 50 Black 525 2.5 Trimethylolpropane tris(2-methyl-1-aziridinium propionate) 0.4 ACRYSOL RM-998 0.12 <![CDATA[DOWSIL TM 210S]]> 2 <![CDATA[DOWSIL TM 8590]]> 0.1 total 55.12

[0142] Table 4. Formulation of the intermediate foam layer

[0143]

[0144] Technology for characterizing products

[0145] (a) Mechanical properties of the PUD epidermal film

[0146] The tensile strength, elongation at break, modulus at 100% elongation, and tear strength of the PUD skin film obtained in Example 4 were characterized according to standard ASTM D412-15a. Higher elongation at break and tensile strength values ​​indicate better performance characteristics.

[0147] (b) Wrinkle resistance test of synthetic leather products

[0148] The wrinkle resistance of synthetic leather was tested according to a method customized based on the standard ISO-105212. Specifically, with the surfaces facing each other, a 100mm x 50mm synthetic leather sample was folded in half to 50mm x 25mm and treated in an oven at 70°C and 95% relative humidity under 5kg pressure for 2 hours. The leather sample was then unfolded and steam-ironed for 5 minutes. Wrinkle resistance was determined based on the presence of horizontal and vertical wrinkles.

[0149] Acceptable: No vertical wrinkles or obvious horizontal wrinkles;

[0150] Unacceptable: Obvious vertical or horizontal wrinkles.

[0151] (c) Anti-adhesion properties of synthetic leather products

[0152] The anti-adhesion of synthetic leather products was characterized according to standard GB / T 8948-2008. Specifically, two 90mm x 60mm synthetic leather product samples were glued together face to face under a pressure of 1kg and heated in an oven at 80°C for 3 hours. The anti-adhesion was determined based on the degree of adhesion between the two samples during separation at room temperature.

[0153] Pass: Completely non-stick or can be separated with very little force;

[0154] Unacceptable: Cannot be separated or can only be separated by large force or the surface is damaged.

[0155] (d) Wet fastness test of synthetic leather

[0156] According to standard ISO-11640, the wet color fastness of synthetic leather is tested. A soaked, wet white wool felt (15mm x 15mm) is loaded onto the end of the rubbing head of the measuring instrument. The wool felt is rubbed back and forth on a leather sample (120mm x 40mm) with a load of 1kg (one rubbing distance is 37mm). The wet color fastness is evaluated based on the color change of the white wool felt after 100 rubbing cycles.

[0157] Pass: No color change after 50 friction cycles.

[0158] Unacceptable: Color changes after 50 friction cycles.

[0159] (e) Test of the softness or feel of synthetic leather

[0160] The result is determined by the touch of an experienced leather expert (pass or fail).

[0161] The performance characteristics of the epidermal films and synthetic leather articles prepared using the PUDs of all embodiments (IE) and comparative embodiments (CE) of the present invention are summarized in Table 5. The performance of CE6 is not shown because the PUD gelled after the degassing process.

[0162] Table 5: Performance characteristics of epidermal films and synthetic leather products

[0163]

[0164]

[0165] A comparison between Examples 1-3 of the present invention and Comparative Examples 1-5 shows that the specific combination of polyetheramine diamine and hydrophilic aminosiloxane in the PUD used for internal emulsification can achieve excellent wrinkle resistance, anti-sticking properties, color fastness and hand feel, while maintaining good mechanical properties, whereas none of the comparative examples that do not contain the above combination can achieve such excellent performance characteristics.

[0166] Furthermore, all embodiments of the present invention can achieve a high solids content of ≥50% by weight, while Comparative Example 5 cannot achieve such a high solids content due to the excessively high viscosity of the PUD prepolymer.

Claims

1. An internally emulsified polyurethane dispersion comprising polyurethane particles dispersed in water, wherein the polyurethane dispersion is derived from starting materials comprising: Component (A): One or more compounds having at least two isocyanate groups; Component (B): One or more compounds having at least two isocyanate reactive groups; Component (C): Hydrophilic aminosiloxane compound represented by formula I: Equation I 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). a -O-CH2-CH=CH2; R1 is -(CH2) m NH2 or -(CH2) s -NH-(CH2) t NH2; R2 is -CH2CH2CH2O(CH2CH2O) n H; and Each of R3, R4, R5, R6, and R7 is independently selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, cyclohexyl, phenyl, and tolyl; Where a is an integer from 1 to 10; x is an integer from 20 to 500; y is an integer from 1 to 20; z is an integer from 1 to 20; m is an integer from 1 to 10; s is an integer from 1 to 10; t is an integer from 1 to 10; and n is an integer from 5 to 30; Component (D): Polyetheramine compound represented by Formula II: Formula II Each of R8 and R9 is independently selected from the group consisting of: hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, cyclohexyl, phenyl, tolyl, and combinations thereof, and q is an integer from 2 to 20; Component (E): C2-C having at least two hydroxyl groups 20 Carboxylic acid compounds; Component (F) catalyst; Component (G) neutralizer; and Component (H) Water; in, The content of component (A) is from 5% to 50% by weight based on the total weight of components (A), (B), (E) and (F). The content of component (B) is 25% to 85% by weight based on the total weight of components (A), (B), (E) and (F); The content of component (E) is from 1% to 10% by weight based on the total weight of components (A), (B), (E) and (F). The content of component (F) is at most 1% by weight based on the total weight of components (A), (B), (E) and (F). The molar ratio between component (G) and component (E) is 1:2 to 2:1; The weight ratio between component (D) and the total weight of components (A), (B), (E), and (F) is from 1:100 to 3:10; and The weight ratio between component (C) and the total weight of components (A), (B), (E) and (F) is 1:50 to 1:

10.

2. The internally emulsified polyurethane dispersion according to claim 1, wherein the polyurethane dispersion does not contain an external emulsifier.

3. The internally emulsified polyurethane dispersion according to claim 1, wherein the polyurethane dispersion has a solids content of more than 45% by weight based on the total weight of the polyurethane dispersion.

4. The internally emulsified polyurethane dispersion according to claim 1, wherein the one or more compounds having at least two isocyanate groups are selected from the group consisting of: a) C4-C12 aliphatic polyisocyanates containing at least two isocyanate groups, C6-C15 alicyclic or aromatic polyisocyanates containing at least two isocyanate groups, C7-C15 aromatic aliphatic polyisocyanates containing at least two isocyanate groups, and combinations thereof. b) A modified polyfunctional isocyanate derived from one or more polyisocyanates of a), wherein the modified polyfunctional isocyanate comprises at least one functional group selected from the group consisting of: ester group, urea group, biuret group, isocyanurate group, urethane group, carbodiimide group, urea ketimide group, and combinations thereof; and c) An isocyanate prepolymer prepared by reacting one or more polyisocyanates of a) with one or more isocyanate reactive compounds selected from the group consisting of: C2-C16 aliphatic polyols containing at least two hydroxyl groups, C6-C15 alicyclic or aromatic polyols containing at least two hydroxyl groups, C7-C15 aryliphatic polyols containing at least two hydroxyl groups, polyester polyols with a molecular weight of 500 to 5,000, polycarbonate diols with a molecular weight of 200 to 5,000, polyether polyols with a molecular weight of 200 to 5,000, C2 to C10 polyamines containing at least two amino groups, C2 to C10 polythiols containing at least two thiol groups, C2-C10 alkanolamines containing at least one hydroxyl group and at least one amino group, and combinations thereof, provided that the isocyanate prepolymer contains at least two free isocyanate end groups.

5. The internally emulsified polyurethane dispersion according to claim 1, wherein the one or more compounds having at least two isocyanate reactive groups are selected from the group consisting of: C2-C16 aliphatic polyols containing at least two hydroxyl groups, C6-C15 alicyclic or aromatic polyols containing at least two hydroxyl groups, C7-C15 aryliphatic polyols containing at least two hydroxyl groups, polyester polyols with a molecular weight of 500 to 5,000, polycarbonate diols with a molecular weight of 200 to 5,000, polyether polyols with a molecular weight of 200 to 5,000, C2 to C10 polyamines containing at least two amino groups, C2 to C10 polythiols containing at least two thiol groups, C2-C10 alkanolamines containing at least one hydroxyl group and at least one amino group, vegetable oils having at least two hydroxyl groups, and combinations thereof.

6. The internally emulsified polyurethane dispersion according to claim 1, wherein the C2-C having at least two hydroxyl groups 20 The carboxylic acid compounds are selected from the group consisting of: dimethylolformic acid, dimethylolacetic acid, dimethylolpropionic acid, dimethylolbutyric acid, dimethylolvalerate, dimethylolhexanoic acid, dimethylolheptanoic acid, dimethylolnonanoic acid, dimethyloldecanoic acid, dimethylollauric acid, dimethylpalmitic acid, dimethylolstearic acid, dimethylolcyclohexanecarboxylic acid, dimethylolbenzoic acid, dihydroxyglutaric acid, tartaric acid, and any combination thereof.

7. The internally emulsified polyurethane dispersion according to claim 1, wherein the catalyst is selected from the group consisting of organotin, organobismuth, tertiary amines, morpholine derivatives, piperazine derivatives, and combinations thereof.

8. A synthetic leather article, comprising, from top to bottom: A polyurethane skin film obtained from an internally emulsified polyurethane dispersion according to any one of claims 1 to 7; Intermediate foam layer; as well as Bottom fabric layer.

9. A method for preparing an internally emulsified polyurethane dispersion according to any one of claims 1 to 7, the method comprising: (i) React component (A) with components (B) and (E) in the presence of component (F) to form a PUD prepolymer; as well as (ii) Neutralize the PUD prepolymer with component (G); as well as (iii) The neutralized PUD prepolymer is combined with components (C), (D) and (H) to form the internally emulsified polyurethane dispersion.

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