HEAT-CURABLE POWDER COATING COMPOSITIONS, WHICH AFTER THE COATING HAS CURED RESULT IN A MATT SURFACE AND SIMPLE METHOD FOR PRODUCING SAME

1 . A powder coating composition, comprising:

A) a polymer comprising a carboxylate group and having an acid number of 5 to 250 mg KOH/g and a glass transition temperature T g of greater than 40° C.;

and

B) a β-hydroxyalkylamide having two or three or four β-hydroxyalkylamide groups per molecule of the formula I

wherein:

R 1 and R 2 are, independently of one another, identical or different radicals selected from the group consisting of an alkyl radical, a cycloalkyl radical, an aryl radical, an aralkyl radical and an alkenyl radical having 1-24 carbon atoms, said radicals optionally comprising a heteroatom, a functional group, or both, and where R 1 may also be hydrogen, such that R 2 is optionally:

A is A 1 , A 2 or A 3 :

 such that radicals R 3 are, independently of one another, identical or different radicals selected from the group consisting of hydrogen, an alkyl radical, a cycloalkyl radical, an aryl radical, an aralkyl radical and an alkenyl radical having 1-24 carbon atoms, said radicals optionally comprising a heteroatom, a functional group, or both, such that two or more substituents R 3 are optionally linked with one another to form rings; and

the β-hydroxyalkylamide is present in solid form below 150° C.;

C) optionally auxiliaries additives, or both;

wherein a ratio of the β-hydroxyalkylamide groups to the carboxylate groups is between 0.5:1 to 1.5:1.

2 . The powder coating composition of claim 1 , wherein the β-hydroxyalkylamide derives from β-hydroxyalkylamines comprising alkyl groups having at least 2 to 10 carbon atoms in the hydrocarbon framework as starting materials, said alkyl groups being linear, branched or cyclic and optionally substituted by at least one heteroatom, and optionally comprising at least one functional group such that the β-hydroxyalkylamines optionally comprise an additional alkyl radical on the nitrogen.

3 . The powder coating composition of claim 1 , comprising β-hydroxyalkylamides of N-alkyl-1,2-alkanolamines and/or of N,N-bis-2-hydroxyalkylamines and esters of cyclohexanedicarboxylic acids.

4 . The powder coating composition of claim 1 , wherein the β-hydroxyalkylamines are hydroxylamines of the formulae II and/or III:

wherein

R 1 is hydrogen, methyl, ethyl, or propyl,

R 2 is methyl;

wherein radicals R 1 simultaneously or independently of one another are hydrogen, methyl, ethyl, or propyl.

5 . The powder coating composition of claim 1 , wherein the following compounds are starting materials for preparing the β-hydroxyalkylamide: diethanolamine (DEA), di-isopropropanolamine (DIPA), di-sec-butanolamine, N-methylethanolamine, N-methylisopropanolamine.

6 . The powder coating composition of claim 1 , wherein the substituent A derives from 1,2-substituted, 1,3-substituted, and 1-4-substituted cyclohexanedicarboxylic acid derivatives.

7 . The powder coating composition of claim 1 , wherein

the β-hydroxyalkylamide is prepared from compounds of the formula IV:

wherein radicals R 4 simultaneously or independently of one another are methyl, ethyl, propyl, or butyl.

8 . The powder coating composition of claim 1 , wherein at least one 1,4-substituted cyclohexanedicarboxylic ester is a starting compound.

9 . The powder coating composition of claim 1 , wherein the β-hydroxyalkylamide B) has at least one of the following formulae:

wherein:

R 2 is methyl,

or

where R 1A is hydrogen and R 1B is methyl, ethyl, or propyl,

or

R 1A is methyl, ethyl, or propyl and R 1B is hydrogen;

A is a 1,4-disubstituted cyclohexane ring of the formula:

a trans content of A is ≧70 mol %; and

at least one β-hydroxyalkylamide B) is present in solid form below 150° C.

10 . The powder coating composition of claim 1 , comprising β-hydroxyalkylamides of dialkyl 1,4-cyclohexyldicarboxylates, with a trans content, based on the position of the carboxyl groups on the cyclohexyl ring, of greater than or equal to 70 mol %.

11 . The powder coating composition of claim 1 , wherein:

the β-hydroxyalkylamide consists of dimethyl 1,4-cyclohexyldicarboxylate and diethanolamine having four β-hydroxyalkylamide groups per molecule of the formula XII:

 having a trans content on the cyclohexyl ring of greater than or equal to 70 mol.

12 . The powder coating composition of claim 1 , wherein the β-hydroxyalkylamide is present in solid form below 150° C.

13 . The powder coating composition of claim 1 , comprising a polyester A) comprising at least one carboxylate group and having:

a glass transition temperature T g in a range from 40 to 80° C.

an acid number varied from 5-250 mg KOH/g;

an OH number of less than 15 mg KOH/g; and

an average molecular weight M w of 1000 to 10 000 g/mol.

14 . The powder coating composition of claim 1 , comprising an acrylate polymer A) comprising at least one carboxylate group and having:

an OH number of less than 10 mg KOH/g;

an acid number of 10 to 350 mg KOH/g;

a Tg of 40 to 110° C.; and

an M W of 500 to 50 000 g/mol.

15 . The powder coating composition of claim 1 , comprising at least one co-crosslinker based on epoxy resins and/or β-hydroxyalkylamides different from the β-hydroxyalkylamide B).

16 . A method for producing the powder coating composition of claim 1 , the method comprising

conducting joint extrusion of all the components in a melt at temperatures between 80 to 150° C.

17 . A process for producing a coating for a matt surface, the process comprising applying the powder coating composition of claim 1 to a surface, wherein the coating has

a gloss to DIN 67530/ISO 2813 of <50 at an incident angle of 60.

18 . The powder coating composition of claim 1 , comprising a N,N,N′,N′-tetrakis(2-hydroxyethyl)cyclohexyl-1,4-diamide according to the formula XIIA as component B),

having the following parameters:

a trans content on the cyclohexyl ring of the N,N,N′,N′-tetrakis(2-hydroxyethyl)cyclohexyl-1,4-diamide of greater than or equal to 70 mol %, based on the total amount of all of the isomers of N,N,N′,N′-tetrakis(2-hydroxyethyl)cyclohexyl-1,4-diamide that are present;

two endothermic peaks according to DSC analysis (differential scanning calorimetry), where peak 1 is situated in the region of 140-170° C. with a maximum of 155-165° C., and peak 2 is situated in the region of 170-210° C. with a maximum of 175-207° C.;

a ratio of the enthalpies of the peak 1 to the peak 2 is 1:1 to 1:5; and

the following peaks in the XRPD spectrum of the powder sample in the x-ray diffractometer, measured with Cu Kα radiation (1.541 Å):

Degrees 2theta ±

Peak #.

0.2 degree 2theta

d (Å)

1

14.90

5.94

2

16.70

5.31

3

17.40

5.09

4

21.20

4.19

5

21.60

4.11

6

26.00

 3.43.

19 . The powder coating composition of claim 18 , having a trans content on the cyclohexyl ring of greater than or equal to 92 mol %, based on the total amount of all of the isomers of N,N,N′,N′-tetrakis(2-hydroxyethyl)cyclohexyl-1,4-diamide that are present.

20 . The powder coating composition of claim 18 , wherein the β-hydroxyalkylamide of the formula XIIA is present in solid form below 175° C.

21 . The powder coating composition of claim 18 , wherein a concentration of all of the isomers of N,N,N′,N′-tetrakis(2-hydroxyethyl)cyclohexyl-1,4-diamide in the end product after its production is 75% by mass.

22 . The powder coating composition of claim 18 , wherein a ratio of the enthalpies of the peak 1 to the peak 2 is 1:1 to 1:3.

23 . The powder coating composition of claim 18 , wherein the N,N,N′,N′-tetrakis(2-hydroxyethyl)cyclohexyl-1,4-diamide,

according to x-ray structural analysis of a single crystal, has the following parameters:

Crystal system:

Orthorhombic

Space group:

Pbca

Unit cell dimensions:

a = 10.06350(10) Å

α = 90°[[.]]

b = 11.85290(10) Å

β = 90°[[.]]

c = 14.6275(2) Å

γ = 90°[[.]]

Volume:

1744.79(3) Å 3 .

24 . A process for producing a coating for a matt surface, the process comprising applying the powder coating composition of claim 18 to a surface, wherein the coating has

matt surfaces with <50 gloss units, measured as reflectometer values to DIN 67530/ISO 2813 with an incident angle of 60°.

25 . The process of claim 24 , wherein the N,N,N′,N′-tetrakis(2-hydroxyethyl)cyclohexyl-1,4-diamide,

according to x-ray structural analysis of a single crystal, has the following parameters:

Crystal system:

Orthorhombic

Space group:

Pbca

Unit cell dimensions:

a = 10.06350(10) Å

α = 90°.

b = 11.85290(10) Å

β = 90°.

c = 14.6275(2) Å

γ = 90°.

Volume:

1744.79(3) Å 3 .

26 - 27 . (canceled)