Hydrophilic polyisocyanates

Abstract

The invention relates to water-soluble or water-dispersible, hydrophilic polyisocyanates and polyisocyanate mixtures, to a process for preparing them, and to their use as a starting component in the production of polyurethane polymers, more particularly as crosslinkers for water-soluble or water-dispersible film-forming binders, adhesives binders, or sealant binders or binder components with or without groups which are reactive towards isocyanate groups.

1 . A hydrophilic, water-soluble or water-dispersible polyisocyanate, comprising 4% to 27% by weight of isocyanate groups, said groups being aliphatically, cycloaliphatically, araliphatically and/or aromatically attached isocyanate groups,
 wherein the polyisocyanate has an average functionality of 2.0 to 5.0 and is synthesized from:   A) at least one diisocyanate or polyisocyanate component having an average functionality of 2.0 to 5.0 and having 8% to 27% by weight of aliphatically, cycloaliphatically, araliphatically and/or aromatically attached isocyanate groups (calculated as NCO; molecular weight=42); and   B) 0.3% to 25% by weight, based on the total weight of components A) and B), of at least one emulsifier (B);   wherein the emulsifier (B) is represented by formula (2):
   X-G-D-H  (2),
 
   wherein:   X is formed from a polyalkylene glycol monoalcohol X′ which is prepared starting from an alkanol and which comprises ethylene oxide units;   G denotes a structural element of the formula (3):   
       
         
           
           
               
               
           
         
         R 5  represents a saturated, unsaturated, branched or unbranched, hydrocarbon radical having at least 2 carbon atoms, wherein when w is greater than one resulting in a plurality of R 5  groups being present in the formula (3), the plurality of R 5  groups may be identical or different; 
         w is greater than or equal to one; 
         D represents an oxyethylene radical or an oxypropylene radical of the formula: —(CH 2 CHR 6 O) z —, where z is greater than or equal to 0, and R 6 ═H or CH 3 ; 
         H represents hydrogen; and 
         w is 1-20; and 
         A) and B) are reacted with one another such that an equivalents ratio of NCO groups to functional groups which are reactive towards NCO groups of 2:1 to 400:1. 
       
     
     
         2 - 5 . (canceled) 
     
     
         6 . The polyisocyanate according to  claim 1 , wherein X′ consists of polyethylene glycol units of the formula: HO(CH 2 CH 2 O) n R 1 , where R 1 =—(CH 2 ) m CH 3 , m=0-3, and n=2-100. 
     
     
         7 - 8 . (canceled) 
     
     
         9 . The polyisocyanate according to  claim 1 , wherein the component A) has an average NCO functionality of 2.0 to 5.0, an isocyanate groups content of 8% to 27% by weight and a monomeric diisocyanates content of less than 1% by weight. 
     
     
         10 . The polyisocyanate according to  claim 1 , wherein the component A), or a precursor of the component A), is selected from the group consisting of 1,4-diisocyanatobutane, 1,6-diisocyanatohexane (HDI), 2-methyl-1,5-diisocyanatopentane, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4-trimethyl-1,6-diisocyanatohexane, 2,4,4-trimethyl-1,6-diisocyanatohexane, 1,10-diisocyanatodecane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanatocyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 2,2′-diisocyanatodicyclohexylmethane, 2,4′-diisocyanatodicyclohexylmethane, 4,4′-diisocyanatodicyclohexylmethane (H 12 MDI), 1-isocyanato-1-methyl-4(3)isocyanatomethylcyclohexane, bis(isocyanatomethyl)norbornane, 1,3-bis(2-isocyanatoprop-2-yl)benzene (TMXDI), 1,4-bis(2-isocyanatoprop-2-yl)benzene (TMXDI), 2,4-diisocyanatotoluene (TDI), 2,6-diisocyanatotoluene (TDI), 2,4′-diisocyanatodiphenylmethane (MDI), 4,4′-diisocyanatodiphenylmethane (MDI), 1,5-diisocyanatonaphthalene, and mixtures thereof. 
     
     
         11 . The polyisocyanate according to  claim 1 , wherein the component A) is at least one polyisocyanate comprising at least one group selected from the group consisting of a uretdione, an isocyanurate, an allophanate, a biuret, a urea, a urethane, an iminooxadiazinedione, and an oxadiazinetrione. 
     
     
         12 . The polyisocyanate according to  claim 1 , wherein
 the component A) is at least one selected from the group consisting of HDI, IPDI, and H 12 MDI.   
     
     
         13 . A process for preparing a hydrophilic, water-soluble or water-dispersible polyisocyanate, the process comprising reacting:
 A) at least one diisocyanate or polyisocyanate component having an average functionality of 2.0 to 5.0 and having 8% to 27% by weight of aliphatically, cycloaliphatically, araliphatically and/or aromatically attached isocyanate groups (calculated as NCO; molecular weight=42); with   0.3% to 25% by weight, based on the total weight of components A) and B), of at least one emulsifier (B), wherein the emulsifier (B) is represented by formula (2):
   X-G-D-H  (2),
 
   wherein:   X is formed from a polyalkylene glycol monoalcohol X′ which is prepared starting from an alkanol and which comprises ethylene oxide units;   G denotes a structural element of the formula (3):   
       
         
           
           
               
               
           
         
         R 5  represents a saturated, unsaturated, branched or unbranched, hydrocarbon radical having at least 2 carbon atoms, wherein when w is greater than one resulting in a plurality of R 5  groups being present in the formula (3), the plurality of R 5  groups may be identical or different; 
         w is greater than or equal to one; 
         D represents an oxyethylene radical or an oxypropylene radical of the formula: —(CH 2 CHR 6 O) z —, where z is greater than or equal to 0, and R 6 ═H or CH 3 ; 
         H represents hydrogen; and 
         w is 1-20; 
         A) and B) are reacted with one another in an equivalents ratio of NCO groups to functional groups which are reactive towards NCO groups of 2:1 to 400:1; 
         the polyisocyanate has an average functionality of 2.0 to 5.0; and 
         the polyisocyanate comprises 4% to 27% by weight of isocyanate groups, said groups being aliphatically, cycloaliphatically, araliphatically and/or aromaticaly attached isocyanate groups. 
       
     
     
         14 . A polyurethane polymer, comprising the polyisocyanate according to  claim 1 , said polymer being suitable as a crosslinker for water-soluble or water-dispersible film-forming binders, adhesives binders, sealant binders or binder components with or without groups which are reactive towards isocyanate groups. 
     
     
         15 . A crosslinker, comprising the polyisocyanate according to  claim 1 , said crosslinker being suitable for water-soluble or water-dispersible film-forming binders or film-forming binder components. 
     
     
         16 . A coating, comprising the polyisocyanate according to  claim 1 , said coating formed from aqueous coating materials based on binders or binder components. 
     
     
         17 . A process, comprising reacting the polyisocyanate according to  claim 1  in blocked form as a reaction component in water-dispersible or water-dispersed film-forming binders or film-forming binder components. 
     
     
         18 . An adjuvant, comprising the a polyisocyanate according to  claim 1 , said adjuvant suitable for aqueous polyurethane dispersions.