Matt powder coatings

Abstract

The invention relates to a branched carboxylic acid functional polyester resin P1 as described herein. The invention further relates to a thermosetting powder coating composition (PCC A1) comprising a binder K1, said binder K1 comprising the P1 and a crosslinker X1. The invention further relates to a cured PCC A1. The invention further relates to a process for making said PCC A1 and processes for coating an article with said PCC A1. The invention further relates to an article having coated thereon said PCC A1 as well as to an article having coated and cured thereon said PCC A1. The invention further relates to a thermosetting powder coating composition B (PCC B) comprising a physical mixture of the thermosetting powder coating composition A1 (PCC A1) with a separate, distinct thermosetting powder coating composition A (PCC A). The invention further relates to a process for making said thermosetting powder coating composition B and processes for coating an article with said PCC B. The invention further relates to a cured PCC B. The invention further relates to an article having coated thereon said thermosetting powder coating composition B as well as to an article having coated and cured thereon said thermosetting powder coating composition B. The invention further relates to use of: the polyester resin P1, the PCC A1, the cured PCC A1, the PCC B, the cured PCC B, articles coated with the PCC A1, articles coated with the PCC B, articles having coated and cured thereon the PCC A1, articles having coated and cured thereon the PCC B. The invention further relates to the use of the polyester resin P1 for matt powder coatings. The invention further relates to the use of the PCC B for matt powder coatings.

Claims

1. A branched carboxylic acid functional polyester resin P1, having: (a) a Tg of at least 40 C. as measured by Differential Scanning Calorimetry (DSC) at a heating rate of 5 C./min; (b) an acid value (AV) of at least 20 and of at most 30 mg KOH/g of the polyester resin P1; (c) a hydroxyl value of at most 7 mg KOH/g of the polyester resin P1; and (d) a functionality of at least 2.1 and of at most 3; wherein the polyester resin P1 is a reaction product of at least the following monomers: i) neopentyl glycol in an amount of at least 25 and at most 50 mol %; ii) ethylene glycol in an amount of at least 5 and at most 20 mol %; iii) a C.sub.6 diol in an amount of at least 1.5 and at most 4.7 mol %; iv) isophthalic acid in an amount of at least 0 and at most 6.5 mol %; v) terephthalic acid in an amount of at least 39 and at most 48 mol %; vi) adipic acid in an amount of at least 1 and at most 10 mol %; and vii) an at least trifunctional monomer in an amount of at least 0.001 and at most 3 mol %; and wherein the mol % is based on a total amount of monomers i)-vii) forming the polyester resin P1 being 100 mol %.

2. The branched carboxylic acid functional polyester resin P1 according to claim 1, wherein the AV is at most 29 mg KOH/g of the polyester resin P1.

3. The branched carboxylic acid functional polyester resin P1 according to claim 1, wherein the AV is at least 20 and at most 28 mg KOH/g of the polyester resin P1.

4. The branched carboxylic acid functional polyester resin P1 according to claim 1, wherein the amount of the at least trifunctional monomer is at least 0.01 and at most 2.5 mol %.

5. The branched carboxylic acid functional polyester resin P1 according to claim 1, wherein the hydroxyl value is at most 6 mg KOH/g of the polyester resin P1.

6. The branched carboxylic acid functional polyester resin P1 according to claim 1, wherein the hydroxyl value is at most 5 mg KOH/g of the polyester resin P1.

7. The branched carboxylic acid functional polyester resin P1 according to claim 1, wherein the hydroxyl value is at most 4.5 mg KOH/g of the polyester resin P1.

8. The branched carboxylic acid functional polyester resin P1 according to claim 1, wherein the hydroxyl value is at most 4.2 mg KOH/g of the polyester resin P1.

9. The branched carboxylic acid functional polyester resin P1 according to claim 1, wherein the hydroxyl value is at most 4 mg KOH/g of the polyester resin P1.

10. A thermosetting powder coating composition A1 (PCC A1) comprising a binder K1 in an amount of at least 20 and at most 100 pph PCC A1, said binder K1 comprising: a crosslinker X1 in an amount of at least 1 and at most 55 pph of the binder K1, wherein the crosslinker X1 is selected from the group consisting of epoxy compounds, BHA compounds having at leest two -hydroxyalkylamide groups and mixtures thereof; and the branched carboxylic acid functional polyester resin P1 according to claim 1 in an amount of at least 45 and at most 99 pph of the binder K1.

11. The thermosetting powder coating composition A1 (PCC A1) according to claim 10, wherein the crosslinker X1 is a BHA compound.

12. A cured thermosetting powder coating composition which obtained by curing the thermosetting powder coating composition A1 as defined in claim 11.

13. A The coated article having a cured coating thereon, wherein the cured coating is obtained by curing the thermosetting powder coating composition according to claim 12.

14. A coated article having a coating thereon comprised of the thermosetting powder coating composition A1 according to claim 11.

15. A two component (2k) thermosetting powder coating composition B (PCC B), comprising a physical mixture of two different, separate and distinct thermosetting powder coating compositions A (PCC A) and A1 (PCC A1), wherein PCC A1 is according to claim 10, and wherein PCC A and PCC A1 are present in PCC B in a total amount which is at least 30 pph of PCC B, and wherein the weight ratio R=weight PCC A/weight PCC A1 is at least 0.3 (and at most 3, and wherein PCC A comprises a binder K in an amount of at least 20 and at most 100 pph PCC A, wherein the binder K comprises: a crosslinker X in an amount of at least 1 and at most 55 pph of binder K, wherein the crosslinker X is selected from the group consisting of epoxy compounds, BHA compounds having at least two -hydroxyalkylamide groups and mixtures thereof; and a branched carboxylic acid functional polyester resin P in an amount of at least 45 and at most 99 pph of binder K, wherein the polyester resin P has: (a) a Tg of at least 40 C. as measured by Differential Scanning calorimetry (DSC) at a heating rate of 5 C./min; (b) an acid value (AV) of at least 65 and of at most 76.8 mg KOH/g of the polyester resin P; (c) a hydroxyl value of at most 10 mg KOH/g of the polyester resin P; and (d) a functionality of at least 3.5 and at most 5; and wherein the polyester resin P is a reaction product of at least the following monomers: i) neopentyl glycol in an amount of at least 19 and at most 38 mol %; ii) ethylene glycol in an amount of at least 8 and at most 21 mol %; iii) a polyol in an amount of at least 0 and at most 2 mol %; iv) isophthalic acid in an amount of at least 0 and at most 2.4 mol %; v) terephthalic acid in an amount of at least 38 and at most 47 mol %; vi) adipic acid in an amount of at least 0.01 and at most 10 mol %; and vii) a polycarboxylic acid, in an amount of at least 6 and at most 10.2 mol %; and wherein the mol % is based on a total amount of monomers i)-vii) forming the polyester resin P being 100 mol %.

16. The thermosetting powder coating composition B according to claim 15, wherein the amount of the polyol monomer iii) is at least 0 and at most 1.4 mol %.

17. The thermosetting powder coating composition B according to claim 15, wherein the AV is at least 68 mg KOH/g of the polyester resin P.

18. The thermosetting powder coating composition B according to claim 15, wherein the neopentyl glycol monomer i) is present in an amount of at most 36.5 mol %.

19. The thermosetting powder coating composition B according to claim 15, wherein the polycarboxylic acid is present in an amount of at least 6.5 mol %.

20. The thermosetting powder coating composition B according to claim 15, wherein the weight ratio R is at least 0.4 and at most 2.5.

21. The thermosetting powder coating composition B according to claim 15, wherein the weight ratio R is at least 0.6 and at most 1.5.

22. The thermosetting powder composition B according to claim 15, wherein the crosslinker X is a BHA compound and the crosslinker X1 is a BHA compound.

23. A cured thermosetting powder coating composition which obtained by curing the thermosetting powder coating composition A1 as defined in claim 15.

24. A coated article having a cured coating thereon, wherein the cured coating is obtained by curing the thermosetting powder coating composition according to claim 23.

25. A coated article having a coating thereon comprised of the thermosetting powder coating composition B according to claim 15.

26. A process for making an article having a coating of a cured thermosetting powder coating composition B, wherein the process comprises the steps of: (a) applying the thermosetting powder coating composition B according to claim 15 to an article to form a coating thereon; and (b) heating and/or radiating the coating of the thermosetting powder coating composition B for enough time and at a suitable temperature to cure the thermosetting powder coating composition B to thereby obtain the article having a coating of the cured thermosetting powder coating composition B.

27. A cured thermosetting powder coating composition which obtained by curing the thermosetting powder coating composition A1 as defined in claim 10.

28. A coated article having a cured coating thereon, wherein the cured coating is obtained by curing the thermosetting powder coating composition according to claim 27.

29. A coated article having a coating thereon comprised of the thermosetting powder coating composition A1 according to claim 10.

30. A process for making an article having coated and cured thereon a thermosetting powder coating composition A1, wherein the process comprises the steps of: (a) applying the thermosetting powder coating composition A1 according to claim 10 to an article to form a coating thereon; and (b) heating and/or radiating the coating of the thermosetting powder coating composition A1 for enough time and at a suitable temperature to cure the thermosetting powder coating composition A1 to thereby obtain the article having a coating of the cured thermosetting powder coating composition A1.

Description

14. EXAMPLES

(1) The invention is explained in more detail with reference to the following non-limiting examples.

(2) In the Examples section: the abbreviation P represents a polyester resin according to the polyester resin P as disclosed herein and as defined by the claims; the abbreviation P1 represents a polyester resin according to the polyester resin P1 as disclosed herein and as defined by the claims; the abbreviation PCC A represents a thermosetting powder coating composition according to the thermosetting powder coating composition PCC A as disclosed herein and as defined by the claims; the abbreviation PCC A1 represents a thermosetting powder coating composition according to the thermosetting powder coating composition PCC A1 as disclosed herein and as defined by the claims; the abbreviation PCC B represents a thermosetting powder coating composition according to the thermosetting powder coating composition PCC B as disclosed herein and as defined by the claims.

(3) In the Examples section: the abbreviation CompP represents a polyester resin that is not according to the polyester resin P as the latter is disclosed herein and as is defined by the claims; the abbreviation CompP1 represents a polyester resin that is not according to the polyester resin P1 as the latter is disclosed herein and as is defined by the claims; the abbreviation CompPCC A represents a thermosetting powder coating composition that is not according to the thermosetting powder coating composition PCC A as the latter is disclosed herein and as defined by the claims; the abbreviation CompPCC A1 represents a thermosetting powder coating composition that is not according to the thermosetting powder coating composition PCC A1 as the latter is disclosed herein and as is defined by the claims; the abbreviation CompPCC B represents a thermosetting powder coating composition that is not according to the thermosetting powder coating composition PCC B as the latter is disclosed herein and as is defined by the claims.

(4) In the Examples the abbreviation n.m. denotes not measured.

(5) In the numbers shown in the Tables, the decimal sign is denoted by a comma ,; for any other number shown in the application, the decimal sign is denoted by a point ..

14.1 Analytical Methods and Techniques for the Measurement of the Properties of the Polyester Resins

(6) Unless otherwise stated the theoretical number average molecular weight (M.sub.n) is defined as follows:
M.sub.n=(.sub.iN.sub.iM.sub.i)/(.sub.iNi)
where N.sub.i is the number of molecules of molecular weight M.sub.i.

(7) In the case of the polyester resins shown in the Examples 1-16, the M.sub.n was calculated by multiplying the functionality (f)as defined hereinwith 56110 and dividing the outcome thereof by the sum of the desired (targeted) acid value (AV) (mg KOH/g polyester resin) and the desired (targeted) hydroxyl value (OHV) (mg KOH/g polyester resin) according to the equation EQ1.

(8) The functionality (f) of the polyester resins shown in the Examples 1-16, was calculated according to equation EQ2.

(9) Melt viscosity (herein mentioned as viscosity, in Pa.Math.s) measurements were carried out at 160 C. on a Brookfield CAP 2000+H Viscometer. The applied shear-rate was 21 s.sup.1 and a 19.05 mm spindle (cone spindle CAP-S-05 (19.05 mm, 1.8) was used.

(10) The acid and hydroxyl values of the polyester resins P, were determined titrimetrically according to ISO 2114-2000 and ISO 4629-1978, respectively; in addition the targeted (theoretical) acid and hydroxyl values of said resins were also reported herein.

(11) The hydroxyl value of the polyester resins P-1, P1-1, P1-2, P1-3 and P1-4 prepared and shown in the Examples section was lower than 5 mg KOH/g polyester resin.

(12) All the polyesters prepared and shown in the Examples section were amorphous.

14.2 DSC Method for the Measurement of Glass Transition Temperature, Crystallization Temperature, Crystallization Enthalpy, Melting Temperature and Melting Enthalpy for Polyester Resins and/or Thermosetting Powder Coating Compositions (Mentioned as DSC Method)

(13) The glass transition temperature, crystallization temperature, crystallization enthalpy, melting temperature and melting enthalpy of a polyester resin, was/is measured via Differential Scanning Calorimetry (DSC) according to the methodology described in this section, on a TA instruments DSC Q20 apparatus, in N.sub.2 atmosphere calibrated with indium, within 24 hours from the time of preparation of the polyester resin. The processing of the signal (DSC thermogram, Heat Flow vs. Temperature) was or is to be carried out using Universal Analysis 2000 software version 4.5a provided by TA instruments, as described herein after. The part of the DSC Method referring to the polyester resins is mentioned herein as DSC Method-PR.

(14) The glass transition temperature, crystallization temperature, crystallization enthalpy, melting temperature and melting enthalpy of a thermosetting powder coating composition was/is measured via Differential Scanning Calorimetry (DSC) according to the methodology described in this section, on a TA instruments DSC Q20 apparatus, in N.sub.2 atmosphere calibrated with indium, within 24 hours from the time of preparation of the polyester resin. The processing of the signal (DSC thermogram, Heat Flow vs. Temperature) was or is to be carried out using Universal Analysis 2000 software version 4.5a provided by TA instruments, as described herein after. The part of the DSC Method referring to the thermosetting powder coating compositions is mentioned herein as DSC Method-TPCC.

(15) Each one of the glass transition temperature of the polyester resin (see DSC Method-PR) and the glass transition temperature of the thermosetting powder coating composition (DSC Method-TPCC) was/is the inflection point temperature of the temperature range over which the glass transition took place, said inflection point temperature was the point on the thermal curve corresponding to the peak of the first derivative (with respect to time) of the parent thermal curve. This point corresponds to the inflection point of the parent thermal curve, as defined in 3.2.1.3 in ASTM E 1356-08.

(16) The T.sub.m (in DSC Method-PR and DSC Method-TPCC) is measured as the temperature recorded at the minimum heat flow of the endothermic signal attributed to the melting of the sample.

(17) The H.sub.m (in DSC Method-PR and DSC Method-TPCC) is measured as the integrated heat flow over the temperature range of the melting.

(18) The T.sub.c (in DSC Method-PR and DSC Method-TPCC) is measured as the temperature recorded at the maximum heat flow of the exothermic signal attributed to the crystallization of the sample.

(19) The H.sub.c (in DSC Method-PR and DSC Method-TPCC) is measured as the integrated heat flow over the temperature range of the crystallization.

14.2.1 Polyester Resins (DSC Method-PR)

(20) The glass transition temperature (T.sub.g in C.) of the polyester resins was measured as follows: a sample of 105 mg of the polyester resin was weight and placed in the DSC cell. The sample was heated up to 150 C. at a heating rate of 40 C./minute (thermograph A). Once the sample has reached 150 C., the temperature was maintained at 150 C. for 10 minutes. Subsequently, the sample was cooled down to 0 C. at a heating rate of 30 C. (thermograph B); once the sample has reached 0 C., the temperature was maintained at 0 C. for 1 minute. Subsequently, the sample was heated up to 100 C. at a heating rate of 5 C./minute (thermograph C). Thermographs A, B and C were processed as the Y axis of the thermographs representing the heat flow having exotherm up and endotherm down. Thermograph C was used to measure the glass transition temperature (T.sub.g) of the polyester resins.

(21) The H.sub.m, T.sub.m, H.sub.c and T.sub.c of a polyester resin are measured as follows: a sample of 105 mg of the crystalline polyester resin is weight and placed in the DSC cell. The sample is equilibrated at 25 C. for 1 minute; Subsequently the sample is heated up to 200 C. at a heating rate of 5 C./minute. Once the sample has reached 200 C., the temperature was maintained at 200 C. for 1 minute (thermograph A). Subsequently, the sample is cooled down to 50 C. at a cooling rate of 5 C./minute (thermograph B); once the sample is reached 50 C., the temperature is maintained at 50 C. for 1 minute. Subsequently, the sample is heated up to 200 C. at a heating rate of 5 C./minute (thermograph C). Thermographs A, B and C were processed as the Y axis of the thermographs representing the heat flow has exotherm up and endotherm down. Thermograph B is used for measuring the H.sub.c and T.sub.c; thermograph C is used to measure the H.sub.m and T.sub.m.

14.2.2 Thermosetting Powder Coating Compositions (DSC Method-TPCC)

(22) The glass transition temperature of the thermosetting powder coating compositions (T.sub.g in C.) is measured 24 h after extrusion as follows: a sample of 105 mg of the thermosetting powder coating composition was weight and placed in the DSC cell. The sample was cooled down to 20 C. and the temperature was kept at 20 C. for 1 minute; Subsequently the sample was heated up to 200 C. at a heating rate of 5 C./minute (thermograph A). Thermograph A was used for measuring the T.sub.g PCC.

(23) The H.sub.m, T.sub.m, H.sub.c and T.sub.c of a thermosetting powder coating composition are measured as follows: a sample of 105 mg of the thermosetting powder coating composition is weight and placed in the DSC cell. The sample is equilibrated at 25 C. for 1 minute; Subsequently the sample is heated up to 120 C. at a heating rate of 5 C./minute. Once the sample has reached 120 C., the temperature was maintained at 120 C. for 1 minute (thermograph A). Subsequently, the sample is cooled down to 50 C. at a cooling rate of 5 C./minute (thermograph B); once the sample is reached 50 C., the temperature is maintained at 50 C. for 1 minute. Subsequently, the sample is heated up to 200 C. at a heating rate of 5 C./minute (thermograph C). Thermographs A, B and C were processed as the Y axis of the thermographs representing the heat flow has exotherm up and endotherm down. Thermograph B is used for measuring the H.sub.c and T.sub.c; thermograph C is used to measure the H.sub.m and T.sub.m.

14.3 Measurement and Assessment of Properties of the Thermosetting Powder Coating Compositions and the Powder Coatings Thereof (Table 6)

(24) The physical storage stability (PSS) of the thermosetting powder coating compositions of Table 7 was tested according to ISO 8130/part 8, at 40 C. for a total of 7 weeks. The measurement of the PSS of said thermosetting powder coating compositions was initiated upon extrusion and cooling down at room temperature for about 3 hours. The greater the extend of agglomeration or sintering the poorer the PSS, thus the lower its ranking according to the following scale. The extent of agglomeration was visually assessed and ranked according to the following rating on a 1-10 scale (1 representing the worst PSS and 10 the best PSS): 10: No change. 9: No agglomeration, very good fluidity. 8: No agglomeration, good fluidity. 7: Very low agglomeration; agglomeration can be dispersed by one light tap into a fine powder. 6: Very low agglomeration; agglomeration can be dispersed by several taps into a fine powder. 5: Low agglomeration; agglomeration can be dispersed by hand pressure into a fine powder. 4: Low agglomeration; agglomeration cannot be dispersed by hand pressure in a fine powder. 3: Severe agglomeration into several large lumps, material is pourable. 2: Severe agglomeration into several large lumps, material is not pourable. 1: product sintered to one lump, volume reduced.

(25) The coating (film) thickness of the powder coatings derived upon heat curing of the corresponding thermosetting powder coating compositions, was measured with a PosiTector 6000 coating thickness gauge from DeFelsko Corporation according to EN ISO 2808:2007.

(26) Reverse impact resistance (RIR) [in.-lb (inch-pounds), 1 inch/lbs=0.055997 m/kg] was tested according to ASTM D 2794, with a ball at 20, 40 and 60 in.-lb and at a film thickness of 505 m on ALQ-46 panels on the same day after the curing took place and the coating was cooled to room temperature. The number of in.-lb mentioned in the row for RIR indicates the maximum in.-lb a powder coating withstood when its corresponding thermosetting powder coating composition was cured for 12 minutes at 160 C. A 0 indicates that the coating did not withstand an impact of 20 in.-lb.

(27) Low bake of a cured thermosetting powder coating composition (or thermosetting cured powder coating composition) is defined herein as the curing temperature and time condition at which the resulted powder coating having coating thickness of 505 m, showed no cracks or delamination after having been subjected to reverse impact resistance was tested on ALQ-46 panels according to ASTM D 2794 as described above.

(28) Gloss60 of the powder coatings derived upon curing of the corresponding thermosetting powder coating compositions on ALQ-46 panels were measured according to ASTM D523 with a BYK-Gardner GmbH Haze-Gloss meter. The gloss is reported at angle 60 in gloss units and it was measured at a film thickness of 605 m on ALQ-46 panels.

14.4 Examples 1-3: Synthesis of Polyester Resins P-1, CompP1-1 and CompP1-2: General

(29) The composition of the polyester resins P-1, CompP1-1 and CompP1-2 as shown in Table 1, refers to a yield of 1.0 Kg of polyester resin.

(30) The polyester resins of Examples P-1, CompP1-1 and CompP1-2 were prepared via a two phase (or two step) polycondensation reaction. At the end of the first step a hydroxyl functional polyester resin was obtained (mentioned herein as precursor); next the hydroxyl functional polyester resin was reacted further with excess of carboxylic acid functional monomers to obtain the polyester resins P-1, CompP1-1 and CompP1-2.

(31) The polyester resins P-1, CompP-1 and CompP-2 are all carboxylic acid functional polyesters and all of them have a hydroxyl value (OHV) lower than 7 mg KOH/g polyester resin.

(32) Each of the polyester resins P-1, CompP1-1 and CompP1-2 was solid at room temperature and at atmospheric pressure.

(33) Each of the polyester resins P-1, CompP1-1 and CompP1-2 was amorphous.

(34) The synthesis of polyester resins CompP1-1 and CompP1-2 was performed analogously to the synthesis of polyester resin P-1 described herein after.

14.4.1 Example 1: Synthesis of Polyester Resin P-1

(35) A reactor vessel fitted with a thermometer, a stirrer and a distillation device for the removal of water formed during the synthesis, was filled with butyl stanoic acid (1 g) (catalyst), neopentyl glycol (288.5 g, 2.77 mol), ethylene glycol (89.0 g, 1.43 mol). The vessel was heated up to 150 C. until the mixture was molten. Then terephthalic acid (571.8 g, 3.44 mol), adipic acid (46.6 g, 0.35 mol) and trimellitic anhydride (20.0 g, 0.10 mol) were added and under a nitrogen flow the temperature was gradually increased to 260 C. while distilling off the reaction water until the acid value of the precursor of the polyester resin was between 9 and 15 mg KOH/g. The reaction mixture was cooled to 240 C. and vacuum was applied until the precursor of the polyester resin reached the desired acid value (7.0 mg KOH/g); that marked the completion of the first step. For the second step the reaction mixture was cooled to 200 C. and subsequently the trimellitic anhydride (113.9 g, 0.59 mol) was added. The temperature was raised to 225 C. and the polyester resin was stirred for one hour at 225 C. Subsequently the polyester resin was cooled down to 195 C. (marking the end of the second step), prior being discharged onto an aluminum foil that was kept at room temperature.

14.5 Examples 4-16: Synthesis of Polyester Resins P1-1, P1-2, P1-3, P1-4 and CompP1-1, CompP1-2, CompP1-3, CompP1-4, CompP1-5, CompP1-6, CompP1-7, CompP1-8, CompP1-9: General

(36) The composition of polyester resins P1-1, P1-2, P1-3, P1-4 and CompP1-1, CompP1-2, CompP1-3, CompP1-4, CompP1-5, CompP1-6, CompP1-7, CompP1-8, CompP1-9 as shown in Tables 2 and 3, refer to a yield of 1.0 Kg of polyester resin.

(37) The polyester resins P1-1, P1-2, P1-3, P1-4 and CompP1-1, CompP1-2, CompP1-3, CompP1-4, CompP1-5, CompP1-6, CompP1-7, CompP1-8, CompP1-9 were prepared via a two phase (or two step) polycondensation reaction. At the end of the first step a hydroxyl functional polyester resin (mentioned herein as precursor) was obtained; next the hydroxyl functional polyester resin was reacted further with excess of carboxylic acid functional monomers to obtain the branched amorphous carboxylic acid functional polyesters of the Examples P1-1, P1-2, P1-3, P1-4 and CompP1-1, CompP1-2, CompP1-3, CompP1-4, CompP1-5, CompP1-6, CompP1-7, CompP1-8, CompP1-9.

(38) The polyester resins of Tables 2 and 3 were all carboxylic acid functional polyesters and all of them had a hydroxyl value (OHV) lower than 5 mg KOH/g polyester resin.

(39) Each of the polyester resins of Tables 2 and 3 was solid at room temperature and at atmospheric pressure.

(40) Each of the polyester resins shown in Tables 2 and 3 was amorphous.

(41) The synthesis of the polyester resins P1-2, P1-3, P1-4 and CompP1-1, CompP1-2, CompP1-3, CompP1-4, CompP1-5, CompP1-6, CompP1-7, CompP1-8, CompP1-9 was performed analogously to the synthesis of polyester resin P1-1 described herein after.

14.5.1 Example 4: Synthesis of the Polyester Resin P1-1

(42) A reactor vessel fitted with a thermometer, a stirrer and a distillation device for the removal of water formed during the synthesis, was filled with butyl stannoic acid (1 g) (catalyst), neopentyl glycol (314.8 g, 3.02 mol), trimethylol propane (8.03 g, 0.06 mol), ethylene glycol (55.0 g, 0.89 mol), 1,6-hexanediol (31.2 g, 0.26 mol). The vessel was heated up to 150 C. until the mixture was molten. Then terephthalic acid (620.2 g, 3.73 mol) and isophthalic acid (23.1 g, 0.14 mol) were added and under a nitrogen flow the temperature was gradually increased to 260 C. while distilling off the reaction water, until the reaction mixture was clear and the acid value of the precursor of the polyester resin was between 5 and 15 mg KOH/g; that marked the completion of the first step. For the second step the reaction mixture was cooled to 200 C. and subsequently the adipic acid (45.8 g, 0.31 mol) and isophtalic acid (44.0 g, 0.26 mol) were added. The temperature was raised to 250 C. while distilling off water; subsequently vacuum was applied until the polyester resin reached the desired acid value range (25.0 mg KOH/g polyester resin). Subsequently, the vacuum was stopped and the polyester resin was cooled down to 195 C. (marking the end of the second step), prior being discharged onto an aluminum foil that was kept at room temperature.

14.6 Preparation of Thermosetting Powder Coating Compositions of Table 4: General Procedure

(43) The components used to prepare the thermosetting powder coating compositions PCC A-1, CompPCC A-1, CompPCC A-2 are described in Table 4; Primid XL-552 (T.sub.m=120-124 C., hydroxyl value 620-700 mg KOH/g Primid XL-552) is a BHA-compound supplied from EMS Chemie and it was used as a crosslinker.

(44) The brown mixture mentioned in Table 4 consisted of 0.4 g Printex 300 (carbon black from Evonik Degussa GmbH), 1.9 g Bayferrox red 130M (Pigment red C.I. 101 Fe2O3 from Bayer B.V.), 2.9 g Bayferrox 920 (C.I. pigment yellow 42 FeOOH from Bayer), 2.2 g SICOTAN Yellow L2010 (chromium(III)/antimony(V)/titanium dioxide rutile from BASF), 25.0 g Blanc fixe micro (precipitated bariumsulphate from Sachtleben Chemie GmbH), 1.5 g Resiflow PV 5 (flow control agent from Worlee-Chemie GmbH) and 0.4 g benzoin (degassing agent). The total amount of the brown mixture used was 34.3 pph binder (=polyester resin and crosslinker). The total amount of the brown mixture that is to be used is 34.3 pph binder (=polyester resin and crosslinker) and the amounts of the individual components of the brown mixture should also be used in a ratio proportional to the one described in this section for the brown mixture. The foregoing applies for any thermosetting powder coating composition (inventive or comparative) that is formulated with the brown mixture.

(45) The thermosetting powder coating compositions of Table 4 were prepared by mixing their components in a blender and subsequently extruding the obtained mixture in a PRISM TSE16 PC twin screw at 120 C. with a screw speed of 200 rpm. The extrudate was allowed to cool at room temperature and it was then chopped into chips. The chips were milled in a Retsch ZM100 with a 0.5 mm ring sieve at 18000 rpm and then sieved. The sieve fraction with particle size below 90 m was collected.

(46) All the thermosetting powder coating compositions of Table 4 were brown.

14.7 Preparation of Thermosetting Powder Coating Compositions of Table 5: General Procedure

(47) The components used to prepare the thermosetting powder coating compositions PCC A1-1, PCC A1-2, PCC A1-3, PCC A1-4, CompPCC A1-1, CompPCC A1-2, CompPCC A1-3, CompPCC A1-4, CompPCC A1-5, CompPCC A1-6, CompPCC A1-7, CompPCC A1-8 and CompPCC A1-9, are described in Table 5; Primid XL-552 (T.sub.m=120-124 C., hydroxyl value 620-700 mg KOH/g Primid XL-552) is a BHA-compound supplied from EMS Chemie and it was used as a crosslinker.

(48) The brown mixture mentioned in Table 5 was the same as the one used for the preparation of the thermosetting powder coating compositions of Table 4 and the total amount of the brown mixture used was 34.3 pph binder (=polyester resin and crosslinker).

(49) The thermosetting powder coating compositions of Table 5 were prepared by mixing their components in a blender and subsequently extruding the obtained mixture in a PRISM TSE16 PC twin screw at 120 C. with a screw speed of 200 rpm. The extrudate was allowed to cool at room temperature and it was then chopped into chips. The chips were milled in a Retsch ZM100 with a 0.5 mm ring sieve at 18000 rpm and then sieved. The sieve fraction with particle size below 90 m was collected.

(50) All the thermosetting powder coating compositions of Table 5 were brown.

14.8 Preparation of Thermosetting Powder Coating Compositions of Tables 6-7: General Procedure

(51) The thermosetting powder coating compositions of Tables 6 and 7 were prepared by physical mixing carried out by mechanical mixing/blending of their components; the components of each of the thermosetting powder coating compositions of Tables 6 and 7 were the two different, separate and distinct thermosetting powder coating compositions of Tables 4 and 5; each of the thermosetting powder coating compositions of Table 6 were prepared by physically mixing in a blender 100 g of each of their components. For example PCC B1 was prepared by physically mixing 100 g of PCC A-1 with 100 g of PCC A1-1. All the thermosetting powder coating compositions of Table 6 were brown.

(52) Each of the thermosetting powder coating compositions of Table 7apart from Example 33 which was prepared as those examples in Table 6were prepared by physically mixing in a blender amounts such amounts of each of their components so that to obtain thermosetting powder coating compositions B having different weight ratios R. For example PCC B8 was prepared by physically mixing 120 g of PCC A-1 with 80 g of PCC A1-1 (R=1.50). All the thermosetting powder coating compositions of Table 7 were brown.

(53) Once prepared the thermosetting powder coating compositions of Table 6, were electrostatically sprayed (corona, 60 kV) onto 0.8 mm thick chromate aluminium Q-panels (type: ALQ-46) to a coating thickness to suit each test mentioned herein and cured at 160 C. for 12 minutes in an air-circulation oven (Heraeus Instruments UT6120) at atmospheric pressure to provide brown powder coatings.

14.9 Preparation of Thermosetting Powder Coating Compositions of Table 8: General Procedure

(54) The components used to prepare the thermosetting powder coating compositions PCC A-2, and PCC A1-5 are described in Table 8; Araldite GT-7004 (softening point=95-101 C., epoxy equivalent 714-752 g/equivalent Araldite GT-7004) is an epoxy compound (epoxy resin) supplied from Huntsman Advanced Materials (Europe) BVBA and it was used as a crosslinker.

(55) The brown mixture mentioned in Table 8 was the same as the one used for the preparation of the thermosetting powder coating compositions of Table 4 wherein each of the individual components of the brown mixture was used in a ratio proportional to the one described for the brown mixture which was used for the preparation of the of Table 4 and wherein the total amount of the brown mixture that was used for the thermosetting powder coating compositions of Table 8 was 34.3 pph binder (=polyester resin and crosslinker).

(56) The thermosetting powder coating compositions of Table 8 were prepared by mixing their components in a blender and subsequently extruding the obtained mixture in a PRISM TSE16 PC twin screw at 120 C. with a screw speed of 200 rpm. The extrudate was allowed to cool at room temperature and it was then chopped into chips. The chips were milled in a Retsch ZM100 with a 0.5 mm ring sieve at 18000 rpm and then sieved. The sieve fraction with particle size below 90 m was collected.

(57) All the thermosetting powder coating compositions of Table 8 were brown.

14.10 Preparation of Thermosetting Powder Coating Compositions of Table 9: General Procedure

(58) The thermosetting powder coating compositions of Table 9 were prepared by physical mixing carried out by mechanical mixing/blending of their components; the components of each of the thermosetting powder coating compositions of Table 9 were the two different, separate and distinct thermosetting powder coating compositions of Table 8; each of the thermosetting powder coating compositions of Table 9 were prepared by physically mixing in a blender such amounts of each of their components so that to obtain thermosetting powder coating compositions B having different weight ratios R. For example PCC B10 was prepared by physically mixing 134 g of PCC A-2 with 66 g of PCC A1-5 (R=2.03). All the thermosetting powder coating compositions of Table 9 were brown.

(59) Once prepared the thermosetting powder coating compositions of Table 9, were electrostatically sprayed (corona, 60 kV) onto 0.8 mm thick chromate aluminium Q-panels (type: ALQ-46) to a coating thickness to suit each test mentioned herein and cured at 160 C. for 12 minutes in an air-circulation oven (Heraeus Instruments UT6120) at atmospheric pressure to provide brown powder coatings.

(60) TABLE-US-00001 TABLE 1 Composition and characterization of a polyester resin according to P (Example 1) and polyester resins comparative to P (Examples 2-3). Example Example 2 Example 3 P-1 CompP-1 CompP-2 Monomers first step Neopentylglycol (mol) 2.77 2.72 2.78 Ethyleneglycol (mol) 1.43 1.43 1.49 Terephthalic acid (mol) 3.44 3.29 3.58 Adipic acid (mol) 0.35 0.35 0.36 Trimellitic anhydride (mol) 0.10 0.12 0.09 Monomers second step Trimellitic anhydride (mol) 0.59 0.71 0.48 Total (mol) 8.69 8.62 8.78 Monomers first step Neopentylglycol (g) 288.5 283.3 289.1 Ethyleneglycol (g) 89.0 88.8 92.7 Terephthalic acid (g) 571.8 547.1 595.1 Adipic acid (g) 46.6 46.6 48.5 Trimellitic anhydride (g) 20.0 23.1 16.7 Monomers second step Trimellitic anhydride (g) 113.9 136.9 92.0 Total weight (g) 1129.8 1125.8 1134.1 Waterformed during synthesis (g) 129.8 125.8 134.1 Weight (g) of resin produced 1000 1000 1000 Monomers Neopentylglycol (mol %) 31.9 31.5 31.6 Ethyleneglycol (mol %) 16.5 16.6 17.0 Terephthalic acid (mol %) 39.6 38.2 40.8 Adipic acid (mol %) 4.0 4.0 4.1 Trimellitic anhydride (mol %) 8.0 9.7 6.5 Total (mol %) 100 100 100 Theoretical values of polyester resin AV (mg KOH/g polyester resin) 73.4 84.4 59.5 OHV (mg KOH/g polyester resin) 5.9 4.8 4.1 Functionality (f) 3.93 4.19 3.99 Mn (Da) 2775 2637 3515 Measured values of polyester resin T.sub.g ( C.) 63.2 64.1 61.7 Viscosity (Pa .Math. s) @ 160 C. 43.9 41.4 50.3 AV (mg KOH/g polyester resin) 71.5 84 61.6 OHV (mg KOH/g polyester resin) 3.8 6.4 4.8

(61) TABLE-US-00002 TABLE 2 Composition and characterization of polyester resins according to P1. Exam- Exam- Exam- Exam- ple 4 ple 5 ple 6 ple 7 P1-1 P1-2 P1-3 P1-4 Monomers first step Neopentylglycol (mol) 3.02 2.99 2.67 2.42 Trimethylolpropane (mol) 0.06 0.07 0.07 0.06 Ethyleneglycol (mol) 0.89 0.88 1.29 1.63 1,6-Hexanediol (mol) 0.26 0.26 0.27 0.26 Isophthalic acid (mol) 0.14 0.10 0.13 0.16 Terephthalic acid (mol) 3.73 3.75 3.81 3.84 Monomers second step Adipic acid (mol) 0.31 0.31 0.31 0.32 Isophthalic acid (mol) 0.26 0.30 0.28 0.25 Total (mol) 8.68 8.67 8.83 8.95 Monomers first step Neopentylglycol (g) 314.8 311.1 278.1 251.7 Trimethylolpropane (g) 8.3 9.5 8.8 8.4 Ethyleneglycol (g) 55.0 54.9 80.3 100.9 1,6-Hexanediol (g) 31.2 31.2 31.7 30.9 Isophthalic acid (g) 23.1 17.4 21.7 26.7 Terephthalic acid (g) 620.2 622.3 632.6 638.7 Monomers second step Adipic acid (g) 45.8 45.8 45.4 47.2 Isophthalic acid (g) 44.0 49.5 46.2 42.3 Total weight (g) 1142.4 1141.6 1144.9 1146.8 Water formed during 142.4 141.6 144.9 146.8 synthesis (g) Weight (g) of resin pro- 1000 1000 1000 1000 duced Monomers Neopentylglycol (mol %) 34.8 34.5 30.3 27.0 Trimethylolpropane 0.7 0.8 0.7 0.7 (mol %) Ethyleneglycol (mol %) 10.2 10.2 14.7 18.2 1,6-Hexanediol (mol %) 3.0 3.0 3.0 2.9 Isophthalic acid (mol %) 4.7 4.6 4.7 4.6 Terephthalic acid (mol %) 43.0 43.2 43.1 43.0 Adipic acid (mol %) 3.6 3.6 3.5 3.6 Total (mol %) 100 100 100 100 Theoretical values of poly- ester resin AV (mg KOH/g polyester 23.8 27.8 24.8 23.8 resin) OHV (mg KOH/g polyester 2.9 3.0 2.7 3.0 resin) Functionality (f) 2.30 2.30 2.31 2.30 Mn (Da) 4823 4196 4715 4822 Measured values of poly- ester resin Tg ( C.) 55.1 55.5 55.1 55.3 Viscosity (Pa .Math. s) @ 160 C. 69.6 55.6 66.3 58.1 AV (mg KOH/g polyester 24.3 27 25.6 24.4 resin) OHV (mg KOH/g polyester 2.7 2.6 2.8 3.8 resin)

(62) TABLE-US-00003 TABLE 3 Composition and characterization of polyester resins comparative to polyester resins P1. Example Example Example Example Example 8 9 10 11 12 Comp Comp Comp Comp Comp P1-1 P1-2 P1-3 P1-4 P1-5 Monomers first step Neopentylglycol (mol) 3.08 3.10 2.91 3.75 3.63 Trimethylolpropane (mol) 0.05 0.04 0.09 0.06 0.06 Ethyleneglycol (mol) 0.89 0.89 0.89 0.16 1,6-Hexanediol (mol) 0.26 0.26 0.27 0.25 0.26 Isophthalic acid (mol) 0.19 0.21 0.05 0.11 0.12 Terephthalic acid (mol) 3.71 3.71 3.76 3.60 3.62 Monomers second step Adipic acid (mol) 0.31 0.31 0.32 0.31 0.30 Isophthalic acid (mol) 0.21 0.20 0.35 0.29 0.27 Total (mol) 8.71 8.72 8.64 8.36 8.43 Monomers first step Neopentylglycol (g) 320.7 322.6 303.0 390.3 377.6 Trimethylolpropane (g) 6.5 5.9 11.7 8.6 8.3 Ethyleneglycol (g) 55.0 55.0 55.4 10.0 1,6-Hexanediol (g) 31.2 31.1 31.4 30.0 30.3 Isophthalic acid (g) 31.8 34.4 8.6 18.3 19.7 Terephthalic acid (g) 616.9 616.0 624.8 597.3 602.2 Monomers second step Adipic acid (g) 45.8 45.8 46.2 44.6 44.5 Isophthalic acid (g) 35.7 33.1 59.0 47.4 45.5 Total weight (g) 1143.5 1143.9 1140.0 1136.5 1138.0 Water formed during 143.5 143.9 140.0 136.5 138.0 synthesis (g) Weight (g) of resin produced 1000 1000 1000 1000 1000 Monomers Neopentylglycol (mol %) 35.3 35.5 33.7 44.8 43.0 Trimethylolpropane (mol %) 0.6 0.5 1.0 0.8 0.7 Ethyleneglycol (mol %) 10.2 10.2 10.3 1.9 1,6-Hexanediol (mol %) 3.0 3.0 3.1 3.0 3.0 Isophthalic acid (mol %) 4.7 4.7 4.7 4.7 4.6 Terephthalic acid (mol %) 42.6 42.5 43.5 43.0 43.0 Adipic acid (mol %) 3.6 3.6 3.7 3.7 3.6 Total (mol %) 100 100 100 100 100 Theoretical values of polyester resin AV (mg KOH/g polyester 17.8 15.9 34.7 24.8 23.8 resin) OHV (mg KOH/g polyester 2.9 3.0 2.7 2.5 3.0 resin) Functionality (f) 2.30 2.30 2.30 2.30 2.30 Mn (Da) 6208 6873 3451 4741 4815 Measured values of polyester resin Tg ( C.) 55 56.3 54.4 56.1 55.8 Viscosity (Pa .Math. s) @ 160 C. 115.7 185.7 37.4 60.9 58.9 AV (mg KOH/g polyester 18.9 16.1 35.7 25.2 24.2 resin) OHV (mg KOH/g polyester 2.5 2.5 2.7 2.8 2.3 resin) Example 13 Example 14 Example 15 Example 16 Comp P1-6 Comp P1-7 Comp P1-8 Comp P1-9 Monomers first step Neopentylglycol (mol) 3.30 3.21 2.86 2.59 Trimethylolpropane (mol) 0.06 0.06 0.06 0.06 Ethyleneglycol (mol) 0.89 0.89 0.88 0.88 1,6-Hexanediol (mol) 0.08 0.42 0.68 Isophthalic acid (mol) 0.14 0.14 0.14 0.13 Terephthalic acid (mol) 3.75 3.74 3.72 3.71 Monomers second step Adipic acid (mol) 0.31 0.31 0.31 0.31 Isophthalic acid (mol) 0.26 0.26 0.26 0.27 Total (mol) 8.72 8.71 8.67 8.63 Monomers first step Neopentylglycol (g) 343.7 334.4 297.4 269.4 Trimethylolpropane (g) 8.3 8.3 8.2 8.4 Ethyleneglycol (g) 55.2 55.1 54.9 54.7 1,6-Hexanediol (g) 10.0 50.0 80.0 Isophthalic acid (g) 23.5 23.4 22.9 22.4 Terephthalic acid (g) 622.5 621.7 618.8 616.7 Monomers second step Adipic acid (g) 46.0 45.9 45.7 45.6 Isophthalic acid (g) 43.8 43.8 44.0 44.3 Total weight (g) 142.9 1142.8 1142.0 1141.5 Water formed during 142.9 142.8 142.0 141.5 synthesis (g) Weight (g) of resin produced 1000 1000 1000 1000 Monomers Neopentylglycol (mol %) 37.9 36.9 33.0 30.0 Trimethylolpropane (mol %) 0.7 0.7 0.7 0.7 Ethyleneglycol (mol %) 10.2 10.2 10.2 10.2 1,6-Hexanediol (mol %) 1.0 4.9 7.8 Isophthalic acid (mol %) 4.6 4.6 4.7 4.7 Terephthalic acid (mol %) 43.0 43.0 43.0 43.0 Adipic acid (mol %) 3.6 3.6 3.6 3.6 Total (mol %) 100 100 100 100 Theoretical values of polyester resin AV (mg KOH/g polyester 23.8 23.8 23.8 23.8 resin) OHV (mg KOH/g polyester 3.0 3.0 3.0 3.0 resin) Functionality (f) 2.30 2.30 2.30 2.30 Mn (Da) 4811 4811 4811 4835 Measured values of polyester resin Tg ( C.) 60.6 58.2 52.7 49.6 Viscosity (Pa .Math. s) @ 160 C. 60.5 58.5 52.4 45.1 AV (mg KOH/g polyester 24.1 23.7 24.4 24.3 resin) OHV (mg KOH/g polyester 3.6 3.3 3.1 2.9 resin)

(63) TABLE-US-00004 TABLE 4 Thermosetting powder coating compositions comprising polyester resins according to P and a crosslinker (Example 17), and thermosetting powder coating compositions comprising polyester resins comparative to P and a crosslinker (Examples 18-19; Comparative). Example 18 Example 19 Example 17 Comp Comp PCC A-1 PCC A-1 PCC A-2 Polyester resin (g) P-1 CompP-1 CompP-2 (89.3) (87.7) (90.8) Primid.sup. XL552 (g) 10.7 12.3 9.2 Brown mixture (g) 34.3 34.3 34.3

(64) TABLE-US-00005 TABLE 5 Thermosetting powder coating compositions comprising polyester resins according to P1 and a crosslinker (Examples 20-23), and thermosetting powder coating compositions comprising polyester resins comparative to P1 and a crosslinker (Examples 24-32; Comparative). Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 24 ple 25 ple 26 ple 27 ple 28 ple 29 ple 30 ple 31 ple 32 ple 20 ple 21 ple 22 ple 23 Comp Comp Comp Comp Comp Comp Comp Comp Comp PCC PCC PCC PCC PCC PCC PCC PCC PCC PCC PCC PCC PCC A1-1 A1-2 A1-3 A1-4 A1-1 A1-2 A1-3 A1-4 A1-5 A1-6 A1-7 A1-8 A1-9 Polyester P1-1 P1-2 P1-3 P1-4 Comp Comp Comp Comp Comp Comp Comp Comp Comp resin (g) (96.0) (95.7) (96.0) (96.0) P1-1 P1-2 P1-3 P1-4 P1-5 P1-6 P1-7 P1-8 P1-9 (96.9) (97.4) (94.4) (96.0) (96.0) (96.0) (96.0) (96.0) (96.0) Primid.sup. 4.0 4.3 4.0 4.0 3.1 2.6 5.6 4.0 4.0 4.0 4.0 4.0 4.0 XL552 (g) Brown 34.3 34.3 34.3 34.3 34.3 34.3 34.3 34.3 34.3 34.3 34.3 34.3 34.3 mixture (g)

(65) TABLE-US-00006 TABLE 6 Thermosetting powder coating compositions (physical mixtures of thermosettingpowder coating compositions of Tables 4 and 5); Examples 33-36 are according to the invention; Examples 37-47 are comparative. Example 37 Example 38 Example 39 Example 40 Example 33 Example 34 Example 35 Example 36 Comp Comp Comp Comp PCC B1 PCC B2 PCC B3 PCC B4 PCC B1 PCC B2 PCC B4 PCC B5 Components of PCC A-1 + PCC A-1 + PCC A-1 + PCC A-1 + PCC A-1 + PCC A-1 + PCC A-1 + PCC A-1 + the PCC B or PCC PCC PCC PCC CompPCC CompPCC CompPCC CompPCC CompPCC B A1-1 A1-2 A1-3 A1-4 A1-2 A1-1 A1-3 A1-4 R 1 1 1 1 1 1 1 1 Properties Low bake Yes Yes Yes Yes No No Yes No PSS 7 9 9 7 8 8 n.m. 8 Properties of the Powder Coatings Gloss 60 30 33 33 33 27 28 44 32 RIR (in.-lb) 60 60 60 60 20 20 60 20 Example 41 Example 42 Example 43 Example 44 Example 45 Example 46 Example 47 Comp Comp Comp Comp CompPCC CompPCC CompPCC PCC 136 PCC B7 PCC B8 PCC B9 B10 B11 B12 Components PCC A-1 + PCC A-1 + PCC A-1 + PCC A-1 + PCC A-1 + CompPCC CompPCC of PCC B or CompPCC CompPCC CompPCC CompPCC CompPCC A-2 + PCC A-1 + CompPCC B A1-5 A1-6 A1-7 A1-8 A1-9 A1-1 PCC A1-1 R 1 1 1 1 1 1 1 Properties Low bake No No No No Yes No No PSS 9 9 9 3 1 9 4 Properties of the Powder Coatings Gloss 60 32 33 32 30 30 38 30 RIR (in.-lb) 20 20 20 20 40 20 0

(66) TABLE-US-00007 TABLE 7 Thermosetting powder coating compositions (physical mixtures of thermosetting powder coating compositions of Tables 4 and 5); Examples 33 and 48-51 are according to the invention; Examples 53-53 are comparative. Example 52 Example 53 Example 48 Example 49 Example 33 Example 50 Example 51 Comp Comp PCG B5 PCC B6 PCC B1 PCC B7 PCC B8 PCC B13 PCC B14 Components of PCC A-1 + PCC A-1 + PCC A-1 + PCC A-1 + PCC A-1 + PCC A-1 + PCCA-1 + the PCC B or PCC PCC PCC PCC PCC PCC A1-1 PCC CompPCC B Al -1 A1-1 A1-1 A1-1 A1-1 A1-1 R 0.67 0.82 1 1.22 1.50 0.11 9 Properties Low bake Yes Yes Yes Yes Yes Yes Yes PSS 5 5 7 6 6 5 6 Properties of the Powder Coatings Gloss 60 36 33 30 36 36 77 79 RIR (in.-lb) 60 60 60 60 60 40 60

(67) TABLE-US-00008 TABLE 8 Thermosetting powder coating composition comprising polyester resin according to P and a crosslinker (Example 54), and thermosetting powder coating composition comprising polyester resin according to P1 and a crosslinker (Example 55). Example 54 Example 55 PCC A-2 PCC A1-5 Polyester resin (g) P-1 P1-1 (36.8) (51.9) Araldite.sup.GT-7004 (g) 37.2 22.3 Triphenyl ethyl 0.37 0.22 phosphonium bromide (g) Brown mixture (g) 25.5 25.5

(68) TABLE-US-00009 TABLE 9 Thermosetting powder coating compositions (physical mixtures of thermosetting powder coating compositions of Table 8); Examples 56-57 are according to the invention; Examples 58-59 are comparative. Example 58 Example59 Example 56 Example 57 CompPCC CompPCC PCC B9 PCC B10 B15 B16 Components of PCC A-2 + PCC A-2 + PCC A-2 + PCC A-2 + the PCC B or PCC A1-5 PCC A1-5 PCC A1-5 PCC A1-5 CompPCC B R 1 2.03 0.11 9 Properties Low bake Yes Yes Yes Yes PSS 9 9 9 9 Properties of the Powder Coatings Gloss 60 35 35 80 74 RIR (in.-lb) 60 60 60 60

(69) The object of the invention was to provide storage stable, low bake thermosetting powder coating compositions that upon curing provide matt powder coatings having good reverse impact resistance (RIR).

(70) By low bake thermosetting powder coating compositions is meant herein brown thermosetting powder coating compositions that upon curing at 160 C. for 12 min, provide brown powder coatings having reverse impact resistance (RIR) of 40 in.-lb at a film thickness of 505 m (1 m=110.sup.6 m), as RIR is defined and measured herein.

(71) By thermosetting powder coating composition having good storage stability is meant herein that a brown thermosetting powder coating composition has a physical storage stability (PSS) of at least 5, more preferably of at least 6, even more preferably of at least 7, on a scale from 1 (very poor storage stability) up to 10 (excellent storage stability), as the PSS is defined and measured herein.

(72) By matt powder coatings or equally low gloss powder coatings is meant herein a brown powder coating having a thickness of 605 m that is obtained upon curing at 160 C. for 12 min of a brown thermosetting powder coating composition, said brown powder coating having a gloss 60 of at most 38, preferably of at most 36, more preferably of at most 35, as gloss 60 is defined and measured herein.

(73) By powder coating having good reverse impact resistance is meant herein a brown powder coating having a thickness of 505 m that is obtained upon curing at 160 C. for 12 min of a brown thermosetting powder coating composition, said brown powder coating is able to withstand at least 40, preferably at least 45, more preferably at least 50, even more preferably at least 55, most preferably at least 60 in.-lb (1 inch/lbs=0.055997 m/kg), as the reverse impact resistance (RIR) is defined and measured herein.

(74) From the results presented in Table 6, 7 and 9, it becomes clear that only thermosetting powder coating compositions B (see Examples 33-36, 48-51, 56-57) as described herein and as defined by the claims presented a unique combination of all the aforementioned desirable properties; more particularly only the thermosetting powder coating compositions B of Examples 33-36, 48-51, and 56-57 were: low bake; and storage stable (PSS in the range of 5-9); and provided upon curing matt powder coatings (gloss60 in the range of 30-36), having a reverse impact resistance of 60 in.-lb.