POLYMERS, PROCESSES, COMPOSITIONS & USES

Abstract

Polymers are provided which are formed of at least one unit selected from the group consisting of the following units S1 and S2:

##STR00001##

wherein X and Y are substituents as defined in the specification and k and m are integers as defined in the specification.

Claims

1. A polymer comprising at least one unit selected from the group consisting of S1 and S2, wherein each of the units S1 and S2 is represented by the following corresponding formula: ##STR00044## wherein i) k is an integer equal to or higher than 0, ii) m is an integer equal to or higher than 0, iii) the sum of k and m, is equal to or higher than 1, iv) X is selected from the group consisting of L4, L7, L9, L10, L11, L12, L13, L20, L23, L24, L25, L26, L27, L28, and L31 as defined in the formulae below, wherein the black dots shown in the formulae of the groups L4 to L31 represent carbon atom attachment points of each of the groups L4 to L31 to the unit S1, v) Y is selected from the group consisting of L4, L7, L9, L10, L11, L12, L13, L20, L23, L24, L25, L26, L27, L28, and L31 as defined in the formulae below, wherein the black dots shown in the formulae of the groups L4 to L31 represent carbon atom attachment points of each of the groups L4 to L31 to the unit S2, ##STR00045## ##STR00046## wherein R.sub.1″, R.sub.2″ is independently selected from the group consisting of H and CHs, R.sub.3″, is a CH.sub.2 or C.sub.2-C.sub.34 optionally-substituted-hydrocarbylene, and R.sub.12″ iS C.sub.4-C.sub.34 unsaturated-acyclic-hydrocarbyl, and wherein the polymer has a functional group which comprises one or both of a cation and an anion, and wherein the polymer has: i) a number average molecular weight (Mr) of at least 10.sup.3 and at most 5×10.sup.4, Da, ii) a polydispersity D (=M.sub.w/M.sub.n) of at least 1.1 and at most 5, iii) a glass transition temperature (T.sub.g) of at least −25 and at most 150° C., iv) an acid value (AV) of at least 10 and at most 350 mg KOH/g, v) a hydroxyl value (OHV) of at least 0 and at most 350 mg KOH/g, and vi) a functionality (f) of at least 0.2 and at most 50, wherein M.sub.w is the weight average weight and is measured via Gel Permeation Chromatography according to the description, and M.sub.n is measured via Gel Permeation Chromatography according to the description, and T.sub.g is measured via Differential Scanning calorimetry according to the description, and AV is measured titrimetrically via ISO 2114, and OHV is measured titrimetrically via ISO 4629, and f is determined by the equation: $f=\frac{\left[M_n\times \left(\mathrm{AV}+\mathrm{OHV}\right)\right]}{56110}.$

2. The polymer according to claim 1, wherein the polymer has: i) a number average molecular weight (Mr) of at most 3×10.sup.4 Da, iii) a glass transition temperature (T.sub.g) of at most 95° C., iv) an acid value (AV) of at least 10 and at most 300 mg KOH/g, v) a hydroxyl value (OHV) of at most 160 mg KOH/g.

3. The polymer according to claim 1, wherein the polymer has: i) a number average molecular weight (Mr) of at most 3×10.sup.4 Da, iii) a glass transition temperature (T.sub.g) of at most 95° C., iv) an acid value (AV) of at least 20 and at most 300 mg KOH/g, v) a hydroxyl value (OHV) of at most 100 mg KOH/g.

4. The polymer according to claim 1, wherein the polymer has a Molar Ratio Q (MRQ) as determined via NMR spectroscopy of at least 1 and at most 10, wherein MRQ is: $\mathrm{MRQ}=\frac{S_{\mathrm{total}}}{S_{\mathrm{specific}}}=\frac{S_{\mathrm{specific}}+S_{\mathrm{rest}}}{S_{\mathrm{specific}}}$ wherein
S.sub.total=S.sub.specific+S.sub.rest,
S.sub.specific=(total moles S1)+(total moles S2), and
S.sub.rest=the total moles of all the units of a polymer wherein said units are not any one of the units S1 and S2.

5. The polymer according to claim 4, wherein the polymer has a MRQ of at most 4.

6. The polymer according to claim 4, wherein the polymer has a MRQ of at most 1.4.

7. The polymer according to claim 4, wherein the polymer has: i) a number average molecular weight (Mr) of at most 3×10.sup.4 Da, iii) a glass transition temperature (T.sub.g) of at most 95° C., iv) an acid value (AV) of at least 10 and at most 300 mg KOH/g, v) a hydroxyl value (OHV) of at most 160 mg KOH/g.

8. The polymer according to claim 5, wherein the polymer has: i) a number average molecular weight (Mr) of at most 3×10.sup.4 Da, iii) a glass transition temperature (T.sub.g) of at most 95° C., iv) an acid value (AV) of at least 10 and at most 300 mg KOH/g, v) a hydroxyl value (OHV) of at most 160 mg KOH/g.

9. The polymer according to claim 6, wherein the polymer has: i) a number average molecular weight (Mr) of at most 3×10.sup.4 Da, iii) a glass transition temperature (T.sub.g) of at most 95° C., iv) an acid value (AV) of at least 10 and at most 300 mg KOH/g, v) a hydroxyl value (OHV) of at most 160 mg KOH/g.

10. The polymer according to claim 6, wherein the polymer has: iv) an acid value (AV) of at least 20 and at most 300 mg KOH/g, v) a hydroxyl value (OHV) of at most 100 mg KOH/g.

11. The polymer according to claim 7, wherein the polymer has: iv) an acid value (AV) of at least 20 and at most 300 mg KOH/g, v) a hydroxyl value (OHV) of at most 100 mg KOH/g.

12. The polymer according to claim 8, wherein the polymer has: iv) an acid value (AV) of at least 20 and at most 300 mg KOH/g, v) a hydroxyl value (OHV) of at most 100 mg KOH/g.

13. A composition comprising a binder, wherein the binder comprises: i) the polymer according to any one of claims 1-10, and ii) a constituent A selected from the group consisting of organic metal salt, thermal initiator, photoinitiator, copolymerizable agent and mixtures thereof.

14. A cured composition, wherein the composition is the composition according to claim 13 which is cured.

15. A product which comprises the polymer according to any one of claims 1-10.

16. A product which comprises the cured composition according to claim 14.

Description

EXAMPLES

[0637] The invention is explained in more detail with reference to the following non-limiting examples.

1 Chemicals, Raw Materials; Analytical Methods and Techniques

1.1 Chemicals & Raw Materials

[0638] Cardura™ E10P (supplied by HEXION; glycidyl ester of Versatic™ Acid 10, is a synthetic saturated monocarboxylic acid of highly branched 010 isomers of the following formula:

##STR00042##

wherein each of Q1′ and Q2′ is a short chain alkyl group and wherein the total number of carbon atoms of both of these alkyl groups is 7. Primid® XL-552 (T.sub.m=120-124° C., OHV=620-700 mg KOH/g) is a BHA-compound supplied from EMS Chemie and it was used as a crosslinker. Kronos® 2360 is titanium dioxide (white pigment) supplied from Kronos Titan GmbH. Resiflow® PV 5 is a flow control agent from Worlée-Chemie GmbH. Benzoin was used as degassing agent. Any other chemicals mentioned in the Examples and not explicitly mentioned in this paragraph, were supplied by Aldrich and they were used as supplied.

1.2 Analytical Methods and Techniques

[0639] The acid value (AV) was measured titrimetrically according to ISO 2114. The AV is given as the mass of potassium hydroxide (KOH) in milligrams that is required to neutralize one gram of the tested substance and is used as a measure of the concentration of carboxylic acid groups present.

[0640] The hydroxyl value (OHV) was measured titrimetrically according to ISO 4629. The OHV is given as the mass of potassium hydroxide (KOH) in milligrams that is required to neutralize one gram of the tested substance and is used as a measure of the concentration of hydroxyl groups present.

[0641] The glass transition temperature (T.sub.g) of the Polymer was measured by Differential Scanning calorimetry (DSC) at a heating rate of 5° C./min in N2 atmosphere at a flow rate of 50 mL/minute, on a TA instruments DSC Q2000 apparatus according to the following method: a sample of 10±0.5 mg was weight and placed in the DSC cell at a temperature between 20 and 25° C. The sample was cooled down to −50° C. and the temperature was kept at −50° C. for time enough for the sample to reach equilibrium; upon equilibration the sample was heated up from −50° C. up to 160° C. at a heating rate of 5° C./minute; the sample was kept at that temperature for 2 minutes and it was subsequently cooled down to −50° C. at a cooling rate of 20° C./min; once the sample reached −50° C. the temperature was maintained for 5 minutes; subsequently, the sample was heated up from −50° C. up to 220° C. at a heating rate of 5° C./minute (thermograph A). The T.sub.g was measured from this last thermograph (thermograph A) as the inflection point of the DSC signal (DSC thermograph, Heat Flow vs. Temperature) The processing of the DSC signal and the determination of the T.sub.g was carried out using Universal Analysis 2000 software version 4.5a provided by TA instruments.

[0642] The glass transition temperature (T.sub.g) of the Binder is measured by Differential Scanning calorimetry (DSC) at a heating rate of 5° C./min in N2 atmosphere at a flow rate of 50 mL/minute, on a TA instruments DSC Q2000 apparatus according to the following method: a sample of 10±0.5 mg is weight and placed in the DSC cell at a temperature between 20 and 25° C. The sample is cooled down to −50° C. and the temperature is kept at −50° C. for time enough for the sample to reach equilibrium; upon equilibration the sample is heated up from −50° C. up to 220° C. at a heating rate of 5° C./minute (thermograph A). The T.sub.g was measured from this last thermograph (thermograph A) as the inflection point of the DSC signal (DSC thermograph, Heat Flow vs. Temperature) The processing of the DSC signal and the determination of the T.sub.g was carried out using Universal Analysis 2000 software version 4.5a provided by TA instruments.

[0643] .sup.1H-NMR or .sup.13C-NMR or .sup.31P-NMR spectroscopy or combinations thereof were used to characterize chemical entities shown herein. .sup.1H-NMR spectra were recorded on a Varian Mercury Vx (400 MHz) spectrometer or on a Bruker Advance (400 MHz) spectrometer at 25° C. in chloroform-d1 unless stated otherwise and referenced versus residual solvent shifts. .sup.13C-NMR spectra were recorded on a Varian Mercury Vx (100 MHz) spectrometer or on a Bruker Advance (100 MHz) spectrometer at 25° C. in chloroform-d1 unless stated otherwise and referenced versus residual solvent shifts. .sup.31P-NMR spectra were recorded on a Varian Mercury Vx (162 MHz) spectrometer or on a Bruker Advance (162 MHz) spectrometer at 25° C. in chloroform-d1: pyridine (70:30 v/v) and referenced versus residual solvent shifts (the .sup.31P-NMR method according to P. Dais and A. Spyros described in Magnetic Resonance in Chemistry 2007; 45:367, may be used).

[0644] The number average molecular weight (M.sub.n) and the weight average molecular weight (M.sub.w) were measured via gel permeation chromatography (GPC) calibrated with a set of polystyrene standards with a molecular weight range of from 500 up to 7×10.sup.6 g/mol and using as eluent stabilized tetrahydrofuran (THF) modified with 0.8% acetic acid at a flow rate of 1 mL/min at 40° C. The GPC measurements were carried out on a Waters Alliance system equipped with: i) an Waters Alliance 2414 refractive index detector at 40° C., and ii) a Waters Alliance 2695 separation module equipped with two consecutive PL-gel columns of Mixed-C type with I/d=300/7.5 mm and filled with particles having a particle size of 10 μm (supplied by the Polymer Laboratories).

[0645] The polydispersity (D) was calculated according to the following equation:

D=M.sub.w/M.sub.n

[0646] The coating (film) thickness of the cured coatings, was measured with a PosiTector 6000 coating thickness gauge from DeFelsko Corporation according to EN ISO 2808:2007.

[0647] Gloss 60° of the powder coatings derived upon curing of the corresponding heat-curable powder coating compositions on ALQ-46 panels were measured according to ASTM D523 with a BYK-Gardner GmbH Haze-Gloss meter. The gloss was measured at a film thickness of 50±5 μm on ALQ-46 panels, recorded at an angle of 60°, and it was reported in gloss units.

[0648] The physical storage stability (PSS) is tested at 23° C. for 3 weeks. Prior to assessing the PSS the heat-curable powder coating composition is left to cool down to 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 is 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.

[0649] The reverse impact resistance (RIR) (inch/lbs; 1 inch/lbs=0.055997 m/kg) was tested according to ASTM D 2794, with a ⅝″ ball at 60 inch/lbs and at a film thickness of 50±5 μm on ALQ-46 panels, one day after the coating was applied, cured at 200° C. for 15 minutes and subsequently cooled at room temperature. If the coating withstood the impact of 60 inch/lbs, then this result was reported as a ‘pass’; if the coating did not withstand the impact of 60 inch/lbs then this result was recorded as ‘fail’.

[0650] The mean particle size and the particle size distribution were measured with the Varian PL-PSDA, particle size distribution analyser. The PL-PSDA uses the principle of packed column hydrodynamic chromatography (HDC) to separate particles in the interstitial void spaces created by the solid spherical column packing material. The HDC chromatogram (calculation of the particle size distribution) may be written as the convolute integral of several factors with respect to time:

F(V)=∫[W(t)G(V,t)K(t)]dt

F(V)=observed chromatogram
W(t)=distribution of sample
G(V,t)=bandspreading of system
K(t)=response of detector
t=time
F(V) is observed while G(V,t) and K(t) can be measured using monodisperse latex standards. K(t), the detector response is actually measured as a function of particle size and converted to a function of time for the calculation. W(t) can then be calculated. The analyser was equipped with a double-piston pump (flow range 0.001-9,999 mL/minute, flow rate reproducibility <0.2% at 2.8 mL/minute; maximum operating pressure 400 Bar). One droplet of the aqueous dispersion was mixed with 10 mL PL-PSDA eluents and filtered over a 5 μm filter. 20 μL of the filtered sample was injected into a column of PL-PSDA cartridge type 2 (size range: 20 to 1500 mm; accuracy of average diameter within 5% or 3 nm; size reproducibility <0.2% short term, 0.8% long term) which had been calibrated using latex particle size standards. A flow of 2.1 mL/minute was applied. The particles eluting from the column were detected using a UV detector (wavelength 254 nm, interference filter; light source: mercury lamp, cell volume 10 μL, sensitivity 6×10.sup.−5 AU, noise 3×10.sup.−5 AU, linearity up to 1.2 AU). The chromatograph was analysed with the help of suitable software that was able to report on the mean particle size and the particle size distribution; the latter was reported herein as either mono-modal or multi-modal.

[0651] By the term ‘Molar Ratio Q’ (abbreviated as MRQ and referring to a polymer comprising units selected from the group consisting of S1, S2, S3, S4, and combinations thereof, as each of S1, S2, S3 and S4 is disclosed herein) is meant herein:

[00005]$\mathrm{MRQ}=\frac{S_{\mathrm{total}}}{S_{\mathrm{specific}}}=\frac{S_{\mathrm{specific}}+S_{\mathrm{rest}}}{S_{\mathrm{specific}}}$

wherein

S.sub.total=S.sub.specific+S.sub.rest, and

S.sub.specific=(total moles S1)+(total moles S2)+(total moles S3)+(total moles S4), and

S.sub.rest=the total moles of all the units of a polymer wherein said units are not any one of S1, S2, S3, S4.

The MRQ is by definition equal to or higher than 1.
The MRQ can be determined by a combination of well-known analytical techniques and a methodology such as those described just below.
At first, one may determine the composition of the polymer via high resolution NMR spectroscopy e.g. .sup.1H-NMR (≥400 MHz), .sup.13C-NMR (≥100 MHz), .sup.31P-NMR (≥162 MHz) [after phosphorylation reaction of the hydroxyl and carboxylic acid groups with 2-chloro-4,4,5,5-tetramethyldioxaphospholane (I) and the related derivative product (II); see method as reported by P. Dais and A. Spyros in Magnetic Resonance in Chemistry 2007, 45:367], or combinations thereof may be used; this is to say that the kind of constitutional units that make up the polymer e.g. monomer residues, or groups of atoms that form distinct residues, and their corresponding amounts are determined. Various well-known 2D NMR techniques such as COSY (homonuclear correlation spectroscopy), HSQC (heteronuclear single-quantum correlation spectroscopy) and HMBC (heteronuclear multiple-bond correlation spectroscopy) may be applied.

[0652] Subsequently, and having determined the polymer composition as described above, one may determine: [0653] i) the total mol of ester groups ( . . . —O—C(═O)— . . . ) originating from the units S1, S2, S3, S4, and [0654] ii) the total mol of any other repeating unit from sequences of monomer residues or group of atoms that form distinct residues, wherein each of said units is different than those of S1, S2, S3, S4.

[0655] The determination of i) can be carried out by .sup.13C-NMR spectroscopy assisted by the co-employment of .sup.1H-NMR and .sup.31P-NMR spectroscopies, focusing on:

[0656] ia) all the carbon atoms present in respectively S1, S2, S3 and S4 (excluding the carbon atoms belonging to X, Y, Z and T) and;

[0657] ib) the first carbon atom of X, Y, Z and T that is directly connected to the ester group of S1, S2, S3, S4, respectively.

If a carbon atom is a tertiary carbon atom, then only .sup.13C-NMR; if a carbon atom is primary or secondary .sup.1H-NMR may be also applied and assist the analysis from the .sup.13C-NMR spectroscopy. Typically, .sup.31P-NMR is used to determine the type of present carboxylic acid and hydroxyl groups present in these units. Various well-known 2D (see above) and/or 3D NMR techniques (e.g. experiments consisting of ‘2D experiments after another’, the triple resonance experiments, etc.) may be used alone or in combination. Upon the completion of this part of the analysis, one is able to determine the total mol of S1, S2, S3 and S4 units, and thus the S.sub.specific.

[0658] The determination of ii) can be carried out by .sup.13C-NMR spectroscopy assisted by the co-employment of .sup.1H-NMR and .sup.31P-NMR spectroscopies, focusing on the carbon atoms present in the sequences of monomer residues or group of atoms that that form distinct residues, and especially to the carbon atoms which are immediately next to the bonds connecting the various units together.

If a carbon atom is a tertiary carbon atom, then only .sup.13C-NMR; if a carbon atom is primary or secondary .sup.1H-NMR may be also applied and assist the analysis from the .sup.13C-NMR spectroscopy. Typically, .sup.31P-NMR is used to determine the type of present carboxylic acid and hydroxyl groups present in these units. Various well-known 2D (see above) and/or 3D NMR techniques (e.g. experiments consisting of ‘2D experiments after another’, the triple resonance experiments, etc.) may be used alone or in combination. Upon the completion of this part of the analysis, one is able to determine the total mol of any unit other than S1, S2, S3 and S4 units, and thus the S.sub.rest.

[0659] Subsequently, given the values for the S.sub.specific and S.sub.rest, one is able to calculate the MRQ by factoring in the equation concerning the MRQ (see above in this paragraph) the values for the S.sub.specific and S.sub.rest.

2 Example of a Polymer According to the Invention and Example of a Process (According the Invention) for Making Said Polymer

2.1 Example 1: Preparation of a Polymer According to § 1.1 Consisting of One S1 Unit, Wherein X is L13

(PEX1)

[0660] Trimellitic anhydride (192.13 g, 1.00 mol) was charged and mixed into a reactor vessel with xylene (290 g) under a nitrogen flow to form a mixture. Cyclohexene oxide (98.14 g, 1.00 mol) was subsequently added dropwise into the reactor. The mixture was subsequently polymerized at a temperature ranging from 130 to 150° C. for 5 hours. The progress of the polymerization reaction was being tracked via measurements of the acid and hydroxyl values. Once an acid value of 280 mg KOH/g was reached, the solvent was removed by applying vacuum and the obtained polymer was discharged from the reaction vessel and collected. The polymer, after drying, was characterized as follows: solid, MRQ=1, T.sub.g=80° C., AV=280 mg KOH/g, OHV=0.5 mg KOH/g; .sup.31P-NMR (δ, ppm, 162 MHz; chloroform-d1:pyridine=:70:30 v/v): 135.6-136.1 (br, m; three groups of resonances, one of them is attributed to the carboxylic acid group of the 51 unit).

3. Examples of Comparative Polymers

3.1 Example 2: Preparation of a Comparative Polymer Comprising One S1, Wherein X is not According to the Invention

(CPEX1)

[0661] Cardura™ E10P (228.33 g, 1.00 mol) and trimellitic anhydride (192.13 g, 1.00 mol) were charged and mixed into a reactor vessel under a nitrogen flow to form a mixture. The mixture was subsequently polymerized at a temperature ranging from 130 to 150° C. for 2.5 hours. The progress of the polymerization reaction was being tracked via measurements of the acid and hydroxyl values. Once an acid value of 147 mg KOH/g was reached, the obtained polymer was discharged from the reaction vessel and collected. The polymer was characterized as follows: solid, MRQ=1, T.sub.g=48° C., M.sub.n=1536 Da, D=2.2, AV=147 mg KOH/g, OHV=6 mg KOH/g).

3.2 Example 2: Preparation of a Comparative Polymer Comprising One S1, One S2, One S3 and One S4 Unit, Wherein X is not According to the Invention

(CPEX2)

[0662] Cardura™ E10P (490 g, 2.15 mol) and citric acid (192 g, 1.00 mol) were charged and mixed into a reactor vessel under a nitrogen flow to form a mixture. The mixture was subsequently polymerized at a temperature of 120° C. for 3 hours. Subsequently, after cooling the reaction mixture to 80° C., isophorone diisocyanate (78 g, 0.35 mol) was added thereto and reacted for 6 hours at 80° C. Furthermore, trimellitic anhydride (115 g, 0.60 mol) was added and reacted for 1 hour at 180° C. The progress of the polymerization reaction was being tracked via measurements of the acid and hydroxyl values. Once an acid value of 65 mg KOH/g was reached, the obtained polymer was discharged from the reaction vessel and collected. The polymer was characterized as follows: solid, MRQ=1.8, T.sub.g=19.6° C., M.sub.n=2189 Da, D=5.3, AV=65 mg KOH/g, OHV=113 mg KOH/g).

[0663] This example corresponded to an effort to reproduce example 8 of U.S. Pat. No. 7,838,076 B2 (=example 8 of EP 1788049 A1). Although the same monomers and amounts were used and the same process was applied, it was not possible to fully reproduce the polymer of example 8 of U.S. Pat. No. 7,838,076 B2 as far as its properties AV and OHV was concerned (the AV and OHV reported for the polymer of example 8 were 80 and 67 mg KOH/g, respectively.

4. Example of a Copolymerizable Polymer A

4.1 Example 4: Preparation of an Acid-Functional Polyester (POL1)

[0664] The polyester resin POL1 was prepared via a two phase (or two step) polycondensation reaction. At the end of the first step a hydroxyl functional polyester (mentioned herein as precursor) was obtained; next the hydroxyl functional polyester was reacted further with excess of carboxylic acid functional monomers to obtain the carboxylic acid functional polyester POL1. More particularly: 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 (0.25 g) (catalyst), neopentyl glycol (432.4 g, 4.15 mol). The vessel was heated up to 150° C. until the mixture was molten. Then terephthalic acid (501.6 g, 3.02 mol) and isophthalic acid (122.4 g, 0.74 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 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 (40.9 g, 0.28 mol) and isophthalic acid (50.3 g, 0.30 mol) were added. The temperature was raised to 250° C. while distilling off water; subsequently vacuum was applied until the polyester reached the desired acid value range (25 mg KOH/g). Subsequently, the vacuum was stopped and the polyester 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. The polyester (acid-functional one) was characterized as follows: T.sub.g=60° C., AV=25 mg KOH/g, OHV=4 mg KOH/g, M.sub.n=3901 Da, D=2.7).

5. Preparation of Heat-Curable Powder Coating Compositions According to the Invention (Inventive) and Coatings Thereof

[0665] PEX1 (which was prepared according to the process of the invention) was used to prepare:

[0666] i) one (individual) 1K white heat-curable inventive powder coating compositions namely PCCA1 (see Table 1), and

[0667] ii) a white inventive powder coating PCA1 was derived upon heat curing of the PCCA1.

[0668] The composition of the 1K white heat-curable inventive powder coating composition PCCA1 is shown in Table 1.

6. Preparation of Heat-Curable Comparative Powder Coating Compositions not According to the Invention and Coatings Thereof

[0669] CPEX1 and CPEX2 were used to prepare: [0670] i) two (individual) 1K white heat-curable comparative powder coating compositions namely PCCC1 and PCCC2 (see Table 1), and [0671] ii) two white comparative powder coatings PCC1 and PCC2 derived upon heat curing of the PCCC1 and PCCC2, respectively.

[0672] The compositions of the 1K white heat-curable comparative powder coating compositions PCCC1 and PCCC2 are shown in Table 1.

[0673] Each of the comparative and inventive 1K white heat-curable powder coating compositions was prepared by mixing its components in a blender and subsequently extruding the obtained mixture in a PRISM TSE16 PC twin screw at 125° C. in which the screw speed was adapted to have a high torque (>80%) to ensure good mixing. 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 18,000 rpm and then sieved. The sieve fraction with particle size below 90 μm was collected, to afford the corresponding inventive and comparative powder coating compositions. Subsequently, each of the inventive and comparative powder coating compositions was electrostatically sprayed (corona, 60 kV) onto 0.8 mm thick chromate aluminium Q-panels (type: ALQ-46) to a coating thickness of 50±5 μm and cured at 200° C. for 15 minutes in an air-circulation oven (Heraeus Instruments UT6120) at atmospheric pressure to afford the corresponding inventive and comparative white powder coatings.

[0674] One of the objects of the invention was to improve the physical storage stability of 1K thermosetting powder coating compositions which are able to afford low gloss (matt) powder coatings upon heat curing at 200° C., without at least compromising the reverse impact resistance.

[0675] By the term ‘matt finish’ or ‘matt powder coatings’ or ‘low gloss powder coatings’ is meant herein a white powder coating having a thickness of 50±5 μm that is obtained upon low bake curing of a white heat-curable powder coating composition, said white powder coating having a gloss 60°—as gloss 60° is defined and measured herein—of at most 50, preferably at most 48, more preferably at most 46, most preferably at most 45, especially at most 43, more especially at most 41, even more especially at most 40, most especially at most 38, for example at most 37, for example at most 36, for example at most 35, for example at most 33, for example at most 32, for example at most 30, for example at most 28, for example at most 26, for example at most 25, for example at most 24, for example at most 22, for example at most 20, for example at most 18, for example at most 16, for example at most 15, for example at most 12, for example at most 10, for example at most 8, for example at most 6.

[0676] By the term ‘very low gloss powder coatings’ is meant herein a white powder coating having a thickness of 50±5 μm that is obtained upon low bake curing of a white heat-curable powder coating composition, said white powder coating having a gloss 60°—as gloss 60° is defined and measured herein—of at most 20.

[0677] By the term ‘excellent physical storage stability’ (or equally ‘excellent storage stability’) (when referring to powder coating compositions) is meant herein that a white heat-curable powder coating composition has a physical storage stability (PSS) of at least 9, on a scale from 1 (very poor storage stability) up to 10 (excellent storage stability), as the PSS is defined and measured herein.

[0678] By the term ‘good physical storage stability’ (or equally ‘good storage stability’) (when referring to powder coating compositions) is meant herein that a white heat-curable powder coating composition has a physical storage stability (PSS) of at least 7 and at most 8, on a scale from 1 (very poor storage stability) up to 10 (excellent storage stability), as the PSS is defined and measured herein.

[0679] By the term ‘poor physical storage stability’ (or equally ‘poor storage stability’) (when referring to powder coating compositions) is meant herein that a white heat-curable powder coating composition has a physical storage stability (PSS) of at most 6, on a scale from 1 (very poor storage stability) up to 10 (excellent storage stability), as the PSS is defined and measured herein.

[0680] By the term ‘good reverse impact resistance’ (RIR) (or equally ‘without compromising the reverse impact resistance’) is meant herein that a white heat-curable powder coating composition scored a ‘pass’ on the relevant test for measuring the reverse impact resistance as this is defined and measured herein.

[0681] By the term ‘poor reverse impact resistance’ (RIR) (or equally ‘compromising the reverse impact resistance’) is meant herein that a white heat-curable powder coating composition scored a ‘fail’ on the relevant test for measuring the reverse impact resistance as this is defined and measured herein.

[0682] It was surprisingly found (see Table 1) that only the polymer of the invention (and the composition of the invention) was able to afford powder coatings that had a unique combination of three very desired properties, such as:

[0683] i) excellent physical storage stability, and

[0684] ii) excellent reverse impact resistance, and

[0685] iii) low gloss 60° (matt coatings), and

Each of the comparative polymers and their compositions failed to afford powder coatings that combined all of the three above-mentioned properties, and in particular they failed on the physical storage stability. The reason being they lacked the specific group X from their chemical structures.

[0686] Therefore, only the inventive polymers (and their powder compositions) offered a surprising solution to the problem of improving the physical storage stability of thermosetting powder coating compositions suitable to afford low gloss powder coatings without compromising the reverse impact resistance of said low gloss powder coatings.

TABLE-US-00001 TABLE 1 Comparative Inventive Composition of the powder coating composition PCCC1 PCCC2 PCCA1 PEX1 (g) (Polymer P) 53 CPEX1 (g) (polymer not according to the invention) 61 CPEX2 (g) (polymer not according to the invention) 68 POL1 (copolymerizable polymer A) 217 216 215 PRIMID ® XL-552 (g) 22 16 31 Kronos ® 2360 150 150 150 Resiflow ® PV5 (g) 4.5 4.5 4.5 Benzoin 1.5 1.5 1.5 Property of the powder coating composition Physical storage stability (PSS) 7 5 9 Property of the coating PCC1 PCC2 PCA1 Gloss60° 4 28 5 Reverse impact resistance Pass Fail Pass (Note: numbers or words describing achieved properties in Table 1 in plain and italics represent properties that are below the desired performance level)

7. Example of a Comparative Polymer and its Aqueous Dispersion

7.1 Example 4: Preparation of a Comparative Polymer Comprising One S1 Unit, Wherein X is not According to the Invention; in this Polymer the X has the Following Formula

[0687] ##STR00043##

wherein R.sub.10″, R.sub.11″ is independently selected from C.sub.1-C.sub.12 saturated-hydrocarbyl, and an aqueous dispersion thereof

(CPEX3, and CPEX3-Aq)

[0688] 11.56 g (0.098 mol) of hexanediol, 289.84 g (1.96 mol) of phthalic anhydride and 1.92 g (20.0 mmol) potassium acetate were weighted in a round bottom vessel and heated to 140° C. under a nitrogen flow. 474.01 g (2.08 mol) Cardura™ E10P was dosed in 3 hours. The reaction was followed by measuring the acid value and the reaction was continued until the acid value reached a value of about 3 mg KOH/g. Subsequently 57.58 g (0.30 mol) trimellitic anhydride was added. The reaction was continued until all trimellitic anhydride was dissolved and reacted. 79.12 g (0.35 mol) Cardura™ E10P was dosed in 0.5 h and the reaction was continued for 1 hour. Step 2 was repeated twice. The obtained polymer had an acid value of 43 mg KOH/g sample and a hydroxyl value of 19 mg KOH/g.

[0689] Aqueous dispersion (CPEX3-Aq): 100 g of the polymer was dissolved in 100 g acetone and heated to 50° C. When the polymer was completely dissolved, 5.41 g triethyl amine (53.5 mmol) was added dropwise followed by the addition of 200 ml water in 10 min. A vacuum was applied to remove the acetone and continued to a final solid content of 40 wt %.

[0690] The final aqueous dispersion showed a broad multi-modal particle size distribution with a mean particle size of 257 nm, a median particle size of 139 nm and a coefficient of variance of 85%. There was a considerable population of large particles with particle size of about 750 nm [see FIG. 1 (A)]. In addition, this aqueous dispersion was not stable over a period of time since after 2 weeks at room temperature flocculation and precipitation took place (visual inspection).

8. Example of an Inventive Polymer and Example of a Process (According the Invention) for Making Said Polymer as Well as an Example of its Aqueous Dispersion

8.1 Example 5: Preparation of a Polymer According to § 1.1 Comprising One S1 Unit, Wherein X is L13 and an Aqueous Dispersion Thereof

(PEX2 and PEX2-Aq)

[0691] 17.17 g (0.145 mol) of hexane diol, 430.51 g (2.91 mol) of phthalic anhydride and 2.85 g (29.1 mmol) potassium acetate were weighted in a round bottom vessel and heated to 140° C. under a nitrogen flow. 305.07 g (3.11 mol) Cardura™ E1 OP was dosed in 3 hours. The reaction was followed by measuring the acid value and the reaction was continued until the acid value reached a value below 3 mg KOH/g. Subsequently 43.21 g (0.225 mol) trimellitic anhydride was added. The reaction was continued until all trimellitic anhydride was dissolved and reacted. 22.06 g (0.225 mol) cyclohexene oxide was dosed in 0.5 h and the reaction was continued for 1.5 hour. Step 2 was repeated twice. The obtained polymer had an acid value of 49 mg KOH/g sample and a hydroxyl value of 25 mg KOH/g.

[0692] Aqueous dispersion (PEX2-Aq): 100 g of the polymer was dissolved in 100 g acetone and heated to 50° C. When the polymer was completely dissolved, 5.41 g triethyl amine (53.5 mmol) was added dropwise followed by the addition of 200 ml water in 10 min. A vacuum was applied to remove the acetone and continued up to a final solid content of 40 wt %.

[0693] The final aqueous dispersion had a narrow mono-modal particle size distribution with a mean particle size of 45 nm, a median particle size of 37 nm and a coefficient of variance of 49%. [see FIG. 1 (B)]. In addition, this aqueous dispersion was stable over a period of time since after 2 weeks at room temperature neither flocculation nor precipitation took place (visual inspection).

[0694] One of the objects of the invention was to provide for stable aqueous dispersions having small particles, for example particles with mean particle size 180 nm, and narrow preferably mono-modal particle size distributions.

[0695] By the term ‘big particles’ (referring to the particles of an aqueous dispersion) is meant herein particles having a mean particle size as this is measured herein of >180 nm.

[0696] By the term ‘small particles’ (referring to the particles of an aqueous dispersion) is meant herein particles having a mean particle size as this is measured herein of 180 nm.

[0697] By the term ‘very small particles’ (referring to the particles of an aqueous dispersion) is meant herein particles having a mean particle size as this is measured herein of 95 nm, preferably 85, more preferably 75, most preferably 65, especially 60 nm.

[0698] By the term ‘coefficient of variation’ (CV) that is also known as relative standard deviation (RSD) is meant a standardized measure of a dispersion of a probability distribution and it is expressed as a percentage and it is defined as the ratio of the standard deviation to the mean value. The CV shows the extent of variability in relation to the mean of the population.

[0699] By the term ‘narrow particle size distribution’ is meant herein that a particle size distribution of an aqueous dispersion has a CV of at most 75%, preferably at most 65%, more preferably at most 55%; preferably the narrow particle size distribution is mono-modal.

[0700] By the term ‘broad particle size distribution’ is meant herein that a particle size distribution of an aqueous dispersion has a CV of at least 76%.

[0701] By the term ‘stable aqueous dispersion’ is meant herein that the aqueous dispersion shows no visible signs of flocculation and/or precipitation upon being stored at RT for 2 weeks.

[0702] It was thus surprisingly found that only the polymers according to the invention were able to afford not only aqueous dispersions that were stable (after 2 weeks at RT), but wherein said aqueous dispersions had a unique combination of very desired properties: [0703] i) having a narrow particle size distribution (mono-modal with a CV of 49%), and [0704] ii) very small particles (mean particle size of 45 nm).
The CPEX3-Aq failed not only to afford a stable aqueous dispersion but most importantly failed to produce an aqueous dispersion having a narrow particle size distribution and small particles. The reason for that was that the group X (in the language of the present invention) was not according to the one claimed by the present invention.

[0705] Table 2 summarizes the results of CPEX3-Aq and PEX2-Aq.

[0706] FIG. 1 presents the particle size distributions of the aqueous dispersions CPEX3-Aq (A) and PEX2-Aq (B).