Coating compositions

1 . A two-part curable coating composition comprising:

(A) a composition comprising an alkoxysilane terminated polyester urethane prepolymer, comprising a prepolymer chain having a terminal group of general formula (I):

wherein:

Y is H, R 1 , or the group:

R 1 is hydrocarbyl;

L is a hydrocarbylene group;

W 1 , W 2 , W 3 , W 4 , W 5 and W 6 are the same or different and each, independently, are —OR 2 , wherein R 2 at each occurrence is the same or different, and each R 2 is, independently, an alkyl group;

and

(B) a composition comprising a silanol terminated polysiloxane prepolymer obtained by sol-gel process of an alkoxysilane that is a compound of general formula (II), (III) or (IV):

wherein:

X 1 , X 2 , X 3 , X 4 , X 5 , and X 6 each are —OR 3 ;

R 3 at each occurrence is the same or different, and each is, independently, an alkyl group; and

m is an integer from 1 to 6;

wherein the sol-gel process comprises reacting the alkoxysilane with at least one acid in the presence of a solvent comprising an alcohol and water.

2 . The composition according to claim 1 , wherein the compositions (A) and/or (B) include at least one or more of the following: solvent; urethane forming catalyst; antistatic agent; stabilizer that is one or more of a UV absorber, light stabilizer or thermal stabilizer; and surface active agent that is one or more of a flow or levelling agent or surfactant.

3 . The composition according to claim 1 , wherein R 1 at each occurrence is the same or different, and each is, independently, a C 1 to C 6 alkyl, or a C 1 to C 4 alkyl group.

4 . The composition according to claim 1 , wherein Y is H.

5 . The composition according to claim 1 , comprising at least one solvent.

6 . The composition according to claim 1 , comprising a urethane forming catalyst.

7 . The composition according to claim 1 , comprising a UV absorber, a light absorber and a thermal stabilizer.

8 . The composition according to claim 1 , comprising a stabilizer combination comprising: a UV absorber, a light absorber and a thermal stabilizer:

wherein the stabilizer combination comprises 6-methylheptyo 2 [4-[4,6-bis (4-phenylphenyl)-1H-1,3,5-triazin-2-ylidene]-3-oxocyclohexa-1,5-dien-1-yl]oxypropanoate, 2,4-bis [N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamine)-1,3,5-triazine and pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate); and/or

wherein the total amount of stabilizers is about 0.5 wt % to about 4 wt %, based on the total weight of solids in the two part curable composition.

9 . The composition according to claim 1 , comprising an antistatic agent.

10 . The composition according to claim 1 , comprising a flow or levelling agent and/or a surfactant.

11 . The composition according to claim 1 , wherein the alkoxysilane-terminated polyester urethane prepolymer in composition (A) is obtained by a process comprising:

(i) reacting an aliphatic diisocyanate with a polyester diol to form an isocyanate-terminated polyester urethane prepolymer; and

(ii) silanizing the isocyanate-terminated polyester urethane prepolymer with an amino-functional alkoxysilane to form the alkoxysilane-terminated polyester urethane prepolymer.

12 . The composition according to claim 11 , wherein the aliphatic diisocyanate in step (i) is a monomeric aliphatic diisocyanate, or a monomeric cycloaliphatic diisocyanate.

13 . The composition according to claim 11 , wherein the polyester diol is a polycaprolactone-based polyester diol.

14 . The composition according to claim 11 , wherein the molar ratio of the polyester diol to aliphatic diisocyanate in step (i) is from: about 1:1.1 to about 1:5.

15 . The composition according to claim 11 , wherein step (i) is carried out in the presence of a urethane forming catalyst, and/or at least one additive that is one or more stabilizers or a flow/leveling agent.

16 . The composition according to claim 11 , wherein step (i) is carried out at a temperature of about 50° C. to about 120° C., and/or wherein the reaction time in step (i) is about 1 to about 4 hours.

17 . The composition according to claim 11 , wherein step (i) further comprises adding an aprotic solvent to the isocyanate-terminated polyester urethane prepolymer to form a homogeneous mixture having a solid content of about 20 to about 80 wt %.

18 . The composition according to claim 11 , wherein the amino-functional alkoxysilane in step (ii) is an aminoalkyltrialkoxysilane, an aminoaryltrialkoxysilane, an aminoalkyl(alkyl)(dialkoxyl)silane, a [bis(trialkoxylsilyl)-alkyl]amine, an N-(aminoalkyl)-aminoalkyltrialkoxysilane, or an N-alkyltrialkoxylsilyl-N, N-dialkylamine.

19 . The composition according to claim 11 , wherein step (ii) comprises adding the amino-functional alkoxysilane to the isocyanate-terminated polyester urethane prepolymer; and/or wherein step (ii) is conducted in the presence of at least one aprotic solvent, and optionally additionally in the presence of a protic solvent in which the isocyanate-terminated polyester urethane prepolymer and the amino-functional alkoxysilane are soluble.

20 . The composition according to claim 11 , wherein step (ii) further comprises adding at least one surfactant to the alkoxysilane-terminated polyester urethane prepolymer.

21 . The composition according to claim 1 , wherein the alkoxysilane is an alkyltrioxysilane, an alkylorthosilicate or a bis(trialkyloxysilyl)alkane.

22 . The composition according to claim 21 , wherein the process comprises adding the alkoxysilane to a mixture comprising the at least one acid, water and an alcohol.

23 . The composition according to claim 21 , wherein the acid comprises a carboxylic acid and/or a mineral acid.

24 . The composition according to claim 21 , wherein the acid is present in an amount to maintain a pH in the range of about 1.5 to about 5.

25 . The composition according to claim 11 , wherein the molar ratio of the amino-functional alkoxysilane in step (ii) to the alkoxysilane in composition (B) is about 1:4 to about 4:1.

26 . The composition according to claim 1 , which is thermally curable.

27 . A polyurethane-polysiloxane hybrid coating composition (PUPSHCC) precursor which is obtained by a process comprising compounding composition (A) and composition (B) of the two-part curable composition of claim 1 .

28 . The polyurethane-polysiloxane hybrid coating composition precursor according to claim 27 , having a solids content of about 10 wt % to about 50 wt %.

29 . A polyurethane-polysiloxane hybrid coating composition which is obtained by a process comprising removing at least a portion of solvent from the polyurethane-polysiloxane hybrid coating composition precursor of claim 27 and subjecting the PUPSHCC precursor to thermal curing.

30 . A process for preparing the two-part curable coating composition of claim 1 , comprising:

(1) preparing the composition (A) comprising the alkoxysilane-terminated polyester urethane prepolymer by a process comprising: (i) reacting an aliphatic diisocyanate with a polyester diol to form an isocyanate-terminated polyester urethane prepolymer; and (ii) silanization of the isocyanate-terminated polyester urethane prepolymer with an amino-alkoxysilane; and

(2) preparing the composition (B) comprising the silanol terminated polysiloxane prepolymer by the sol-gel process comprising reacting the alkoxysilane with the at least one acid, in the presence of the solvent comprising the alcohol and water.

31 . A method comprising coating a substrate with the composition according to claim 1 .

32 . A substrate comprising the polyurethane-polysiloxane hybrid polymer coating composition of claim 29 .

33 . A process for preparing the substrate according to claim 32 , comprising applying the polyurethane-polysiloxane hybrid coating composition precursor of claim 27 to a surface of a substrate, removing at least a portion of the solvent, from the polyurethane-polysiloxane hybrid coating composition precursor, and thermally curing the coating composition precursor to provide a substrate coated with the polyurethane-polysiloxane hybrid coating composition, and wherein the surface of the substrate comprises an electrically conductive layer, onto which the polyurethane-polysiloxane hybrid coating composition precursor is applied.

34 . The composition according to claim 5 , wherein the solvent comprises an aprotic solvent and a protic solvent, wherein the aprotic solvent is ethyl 3-ethoxypropionate, n-pentyl propionate, 2-butoxyethyl acetate, di-isobutyl ketone, or methyl isobutyl ketone, or a combination thereof; and/or the protic solvent is a hydroxyketone.

35 . The composition according to claim 6 , wherein the urethane forming catalyst is dibutyltin dilaurate or dibutyltin diacetate; and/or wherein the urethane forming catalyst is present in an amount of about 0.1 ppm to about 100 ppm, based on the total weight of solids in the composition.