Waterborne polyurethane dispersion and method for preparing the same

Abstract

Provided is a waterborne polyurethane dispersion. The waterborne polyurethane dispersion is prepared in the presence of a hydrophilic amino siloxane compound and exhibits good anti-stickiness while retaining superior mechanical properties. A laminated synthetic leather article prepared with said waterborne polyurethane dispersion as well the method for preparing the synthetic leather article are also provided.

1 . A waterborne polyurethane dispersion comprising polyurethane particles dispersed in water, wherein the waterborne polyurethane dispersion is derived from:
 (A) an isocyanate component comprising one or more compounds having at least two isocyanate groups;   (B) an isocyanate-reactive component comprising one or more compounds having at least two isocyanate-reactive groups;   (C) a hydrophilic amino siloxane compound represented by Formula I:   
       
         
           
           
               
               
           
         
         wherein each R independently represents methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, n-pentyl, i-pentyl, tert-pentyl, neo-pentyl, cyclohexyl, phenyl, vinyl, allyl or —(OCH 2 CH 2 ) a —O—CH 2 —CH═CH 2 ; 
         R 1  is —(CH 2 ) m NH 2  or —(CH 2 ) s —NH—(CH 2 ) t NH 2 ; 
         R 2  is —CH 2 CH 2 CH 2 O(CH 2 CH 2 O) n H; and 
         each of R 3 , R 4 , R 5 , R 6  and R 7  is independently selected from the group consisting of methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, n-pentyl, i-pentyl, tert-pentyl, neo-pentyl, cyclohexyl and phenyl; 
         wherein a is an integer of 1 to 10; x is an integer of 20-500; y is an integer of 1-10; z is an integer of 1-10; m is an integer of 1-5; s is an integer of 1, 2, 3, 4 or 5; t is an integer of 1, 2, 3, 4 or 5; and n is an integer of 5-20; and wherein the content of the hydrophilic amino siloxane compound (C) is from 2.0 wt % to 10 wt %, based on the total weight of the isocyanate component (A), the isocyanate-reactive component (B), and the catalyst (D); 
         (D) a catalyst; 
         (E) a surfactant; 
         (F) a chain extender; and 
         (G) water. 
       
     
     
         2 . The waterborne polyurethane dispersion according to  claim 1 , wherein there is no cationic or anionic hydrophilic pendant groups or groups which can be converted into the cationic or anionic hydrophilic pendant groups covalently attached to the backbone chain of polyurethane in the polyurethane particles, and the polyurethane is externally emulsified. 
     
     
         3 . The waterborne 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 comprising at least two isocyanate groups, C6-C15 cycloaliphatic or aromatic polyisocyanates comprising at least two isocyanate groups, C7-C15 araliphatic polyisocyanates comprising at least two isocyanate groups, and a combination thereof; and   b) an isocyanate prepolymer prepared by reacting one or more polyisocyanates of a) with one or more isocyanate-reactive components selected from the group consisting of C2-C16 aliphatic polyhydric alcohols comprising at least two hydroxy groups, C6-C15 cycloaliphatic or aromatic polyhydric alcohols comprising at least two hydroxy groups, C7-C15 araliphatic polyhydric alcohols comprising at least two hydroxy groups, polyester polyols having a molecular weight from 500 to 5,000, polycarbonate diols having a molecular weight from 200 to 5,000, polyetherdiols having a molecular weight from 200 to 5,000, C2 to C10 polyamine comprising at least two amino groups, C2 to C10 polythiol comprising at least two thiol groups, C2-C10 alkanolamine comprising at least one hydroxyl group and at least one amino groups, and a combination thereof, with the proviso that the isocyanate prepolymer comprises at least two free isocyanate terminal groups.   
     
     
         4 . The waterborne polyurethane dispersion according to  claim 1 , wherein the content of the isocyanate component (A) is from 5 wt % to 50 wt %, based on the total weight of the isocyanate component (A), the isocyanate-reactive component (B) and the catalyst (D). 
     
     
         5 . The waterborne 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 polyhydric alcohols comprising at least two hydroxy groups, C6-C15 cycloaliphatic or aromatic polyhydric alcohols comprising at least two hydroxy groups, C7-C15 araliphatic polyhydric alcohols comprising at least two hydroxy groups, polyester polyols having a molecular weight from 500 to 5,000, polycarbonate diols having a molecular weight from 200 to 5,000, polyetherdiols having a molecular weight from 200 to 5,000, C2 to C10 polyamine comprising at least two amino groups, C2 to C10 polythiol comprising at least two thiol groups, C2-C10 alkanolamine comprising at least one hydroxyl group and at least one amino groups, vegetable oil having at least two hydroxyl groups, and a combination thereof. 
     
     
         6 . The waterborne polyurethane dispersion according to  claim 1 , wherein the content of the isocyanate-reactive component (B) is from 50 wt % to 95 wt %, based on the total weight of the isocyanate component (A), the isocyanate-reactive component (B) and the catalyst (D). 
     
     
         7 . The waterborne polyurethane dispersion according to  claim 1 , wherein the catalyst (D) is selected from the group consisting of: organotin compound, organic dismuth compound, tertiary amine, morpholine derivative, piperazine derivative, and combination thereof; and
 wherein the content of the catalyst (D) is 1.0 wt % or less, based on the total weight of the isocyanate component (A), the isocyanate-reactive component (B) and the catalyst (D).   
     
     
         8 . The waterborne polyurethane dispersion according to  claim 1 , wherein the surfactant (E) is selected from the group consisting of: poly(oxy-1,2-ethanediyl) α-sulfo-ω(nonylphenoxy) salt, alkali metal oleates and stearates, alkali metal C12-C16 alkyl sulfates, amine C 12 -C 16  alkyl sulfates, alkali metal C 12 -C 16  alkyl benzene sulfonates, amine C 12 -C 16  alkyl benzene sulfonates, fluorinated C 4 -C 16  alkyl esters, alkali metal C 4 -C 16  perfluoroalkyl sulfonates, and the combination thereof; and
 wherein the content of the surfactant (E) is 10 wt % or less, based on the total weight of the isocyanate component (A), the isocyanate-reactive component (B) and the catalyst (D). 
 
     
     
         9 . The waterborne polyurethane dispersion according to  claim 1 , wherein the chain extender (F) is selected from the group consisting of: C 2 -C 16  aliphatic polyamine comprising at least two amine groups, C 4 -C 15  cycloaliphatic or aromatic polyamine comprising at least two amine groups, C 7 -C 15  araliphatic polyamine comprising at least two amine groups; and
 wherein the content of the chain extender (F) is from 1.0 wt % to 15 wt %, based on the total weight of the isocyanate component (A), the isocyanate-reactive component (B) and the catalyst (D).   
     
     
         10 . The waterborne polyurethane dispersion according to  claim 1 , wherein the waterborne polyurethane dispersion has a solid content of 5 wt % to 50 wt %, based on the total weight of the waterborne polyurethane dispersion; and
 the polyurethane particles have a volume average particle size of 20 nm to 5 μm.   
     
     
         11 . A method for preparing the waterborne polyurethane dispersion according to  claim 1 , the method comprising
 (i) reacting the isocyanate component (A) with the isocyanate-reactive component (B) in the presence of the catalyst (D) to form a prepolymer; and   (ii) reacting the prepolymer with the hydrophilic amino siloxane compound (C) and the chain extender (F) in the presence of the surfactant (E) and water (G) to form the waterborne polyurethane dispersion.   
     
     
         12 . A synthetic leather article, comprising, from top to bottom:
 a polyurethane skin film derived from the waterborne polyurethane dispersion according to  claim 1 ;   a base layer derived from a 2k PU composite composition; and   an optional backing substrate, wherein the polyurethane skin film directly contacts with the base layer, and the backing substrate, when present, directly contacts with the base layer.   
     
     
         13 . A method for preparing a synthetic leather article comprising:
 a) providing the waterborne polyurethane dispersion according to  claim 1 ;   b) forming the polyurethane skin film with the waterborne polyurethane dispersion;   c) applying the 2k PU composite composition onto one side of the polyurethane skin film to form the base layer; and   d) optionally, applying the backing substrate onto one side of the base layer opposite the polyurethane skin film.