HYDROXYLATED AND/OR CARBOXYLATED POLYESTER RESIN WITH HIGH SOLIDS CONTENT AND HIGH COVERING POWER FOR COATING OF METAL FOIL

Abstract

The invention is directed to a polyester resin bearing at least two functions from among hydroxyl and/or carboxyl, based on: A) a polyol component comprising a1) at least one diol bearing at least two lateral C.sub.2 to C.sub.4 alkyl substituents, a2) at least one diol bearing at least one lateral methyl substituent, a3) at least one C.sub.2 to C.sub.6 diol bearing no lateral substituent, a4) optionally, at least one polyol with functionality >2 and B) a polyacid component comprising b1) at least one aromatic diacid, b2) at least one linear C.sub.4 to C.sub.10 aliphatic diacid, b3) optionally, at least one cycloaliphatic diacid, said resin being free of any unsaturated fatty monoacid or monoalcohol. The invention is further directed to the polyester resin in solution in an organic solvent and crosslinkable compositions comprising it, particularly for metal foil coatings (coils).

Claims

1. A polyester resin bearing at least two functions from among hydroxyl and/or carboxyl, wherein the structure of said polyester resin is branched and includes the components: A) a polyol component comprising: a1) at least one C.sub.3 to C.sub.6 diol bearing at least two lateral C.sub.2 to C.sub.4, alkyl substituents, a2) at least one C.sub.3 to C.sub.6 diol, bearing at least one lateral methyl substituent, a3) at least one linear C.sub.2 to C.sub.6 diol, bearing no lateral (alkyl) substituent, a4) at least one polyol with functionality >2 and B) a polyacid component comprising: b1) at least one aromatic diacid or its anhydride, b2) at least one linear C.sub.4 to C.sub.10 aliphatic diacid b3) optionally, a cycloaliphatic diacid said resin being free of any unsaturated fatty monoacid and of any unsaturated fatty monoalcohol and having a glass transition temperature measured by DSC at 10 C./min, from 10 C. to 50 C. and a calculated Mn ranging from 500 to 10,000.

2. The polyester resin as claimed in claim 1, wherein said diol a1) is 2-butyl-2-ethyl-1,3-propanediol.

3. The resin as claimed in claim 1 wherein said diol a1) represents from 3 to 25% by weight of said resin.

4. The resin as claimed in claim 1 wherein a3) is present and the a1/(a1+a2+a3) molar ratio varies from 0.1 to 0.4.

5. The resin as claimed in claim 1 wherein said polyol a2) is a diol selected from the group consisting of: neopentyl glycol (2,2-dimethyl-1,3-propanediol) and dimethyl butanediol.

6. The resin as claimed in claim 5, wherein the content of weight of said polyol a2) is less than 75% by weight of said polyol component A).

7. (canceled)

8. The resin as claimed in claim 1 wherein the acid component B) of said resin comprises at least one cycloaliphatic carboxylic diacid b3) or its anhydride.

9. The resin as claimed in claimed 1 wherein said resin has a hydroxyl index or a carboxyl index or a global hydroxyl+carboxyl index ranging from 10 to 200 mg KOH/g.

10. The resin as claimed in claimed 1 wherein said resin is hydroxylated.

11. The resin as claimed in claim 1 having a (calculated) Mn ranging from 1000 to 10 000.

12. A resin solution comprising at least one resin according to claim 1 and an organic solvent of said resin.

13. The resin solution as claimed in claim 12, wherein the content by weight of said resin relative to the total resin+solvent weight is greater than 60%.

14. A crosslinkable binder composition comprising as binder at least one polyester resin according to claim 1.

15. The composition as claimed in claim 14, comprising at least one organic solvent with the content of said resin ranging from 60% to 90% relative to the total resin+solvent weight.

16. The composition of claim 14 which is a coating composition.

17. The composition as claimed in claim 16, further comprising at least one crosslinking agent bearing groups that react with the hydroxyl and/or carboxyl groups borne by said resin.

18. The composition as claimed in claim 17, wherein said crosslinking agent is selected from the group consisting of melamine, polyisocyanate, polyanhydride, and polysilane, when said resin is hydroxylated or said crosslinking agent is selected from the group consisting of polyepoxides and polyols when said resin is carboxylated.

19. (canceled)

20. The composition as claimed in claim 14 further comprising at least one pigment.

21. (canceled)

22. (canceled)

23. (canceled)

24. (canceled)

25. (canceled)

26. (canceled)

27. A coating characterized in that it results from the use of at least one resin as defined according to one of claims 1 to 11, of a resin solution as defined according to claim 12 or 13 or of a coating composition as defined according to one of claims 14 to 20.

28. The coating as claimed in claim 27, characterized in that it is a metal foil (coil) coating.

29. The resin as claimed in claim 1 wherein said diol a) is a C.sub.3 or C.sub.4 diol.

30. The resin as claimed in claim 1, wherein the b1/b2 molar ratio ranges from 1/1 to 4/1.

Description

EXPERIMENTAL SECTION

1) Preparation of the Resin for Primer Coating

1.1) Raw Materials Used

[0061]

TABLE-US-00001 TABLE 1 Raw materials used Typical Nature of the composition Chemical Technical function/ according to the Trade name name Supplier function functionality invention PAN Phthalic Polynt Monomer Carboxyl/2 Diacid b1) anhydride EG Ethylene Dow Monomer Hydroxyl/2 Diol a3) glycol NPG Neopentyl Perstorp Monomer Hydroxyl/2 Diol a2) glycol BEPD Butyl ethyl Perstorp Monomer Hydroxyl/2 Diol a1) propanediol AA Adipic acid Bayer Monomer Carboxyl/2 Diacid b2) HDD 1-6 Hexane Perstorp Monomer Hydroxyl/2 Diol a3) diol Solvarex 9 Aromatic Total Solvent for the Solvent for the solvent resin resin BG Butyl glycol Brenntag Solvent for the Solvent for the resin resin Fascat 4100 Tin PMC Catalyst Catalyst monobutyl Organometallix oxide Xylene Xylene Total Azeotropic carrier Azeotropic carrier solvent solvent
1.2) Procedure for Resin Preparation: According to the Invention (Example 1) and Comparison Test 1 without BEPD

[0062] In a 1.5 L glass reactor equipped with: [0063] a Vigreux distillation column with a Dean Stark separator on it, [0064] a dipping rod for adding nitrogen, [0065] a temperature probe,
the monomers are charged in quantities as described in Table 2.

[0066] The synthesis takes place at a maximum of 220 C. in the presence of a catalyst (Fascat 4100: 0.08 g) and xylene as azeotropic carrier (30 g) to remove water from the reaction.

[0067] The resin according to the invention (example 1) is diluted in pure Solvarex 9 and in a Solvarex 9/butylglycol mixture (70/30) for the resin of comparison test 1.

[0068] The characteristics of the two resins are given in Table 2.

TABLE-US-00002 TABLE 2 Compositions and characteristics of resins (without solvent, catalyst and azeotropic carrier) according to the invention (example 1) and comparison test 1 Test according to Comparison test 1 the invention (example 1) Phthalic anhydride 706 555 Ethylene glycol 84 83 Neopentyl glycol 210 121 BEPD 80 (Butyl ethyl propanediol) 1,6 Hexanediol 131 Adipic acid 30 TOTAL 1000 1000 Hydroxyl index 30 37 (mg KOH/g) (ISO 2554 method) Acid index 4 4 (mg KOH/g) (ISO 2114 method) Solids content (%) 64.3 76 (ISO 3251 method) Brookfield viscosity at 3500 11 700 25 C. (mPa .Math. s) (ISO 3219 method) at the solids content indicated Calculated Mn 3050 2530

2) Preparation of the Resin for Finishing Coating

2.1) Raw Materials Used

[0069]

TABLE-US-00003 TABLE 3 Raw materials used Typical Nature of the composition Chemical Technical function/ according to Trade name name Supplier function functionality the invention PAN Phthalic Polynt Monomer Carboxyl/2 Diacid b1) anhydride AA Adipic acid Bayer Monomer Carboxyl/2 Diacid b2) Glycerine Glycerol Oleon Monomer Hydroxyl/3 Polyol a4) NPG Neopentyl glycol Perstorp Monomer Hydroxyl/2 Diol a2) BEPD Butyl ethyl Perstorp Monomer Hydroxyl/2 Diol a1) propanediol TMP Trimethylol Perstorp Monomer Hydroxyl/3 Polyol a4) propane Solvarex 9 Aromatic solvent Total Solvent for the Solvent for resin the resin BG Butyl glycol Brenntag Solvent for the Solvent for resin the resin Fascat Tin monobutyl PMC Catalyst Catalyst 4100 oxide Organometallix Xylene Xylene Total Azeotropic Azeotropic carrier solvent carrier solvent
2.2) Procedure for Resin Preparation: According to the Invention (Example 2) and Comparison Test 2 without BEPD

[0070] The procedure used is identical to that described in the procedure in point 1.2) above (the proportions are given in Table 4).

[0071] The resin according to the invention (example 2) is diluted in pure Solvarex 9 and in a Solvarex 9/butylglycol mixture (70/30) for the resin of comparison test 2.

[0072] The characteristics of the two resins are also given in Table 4.

TABLE-US-00004 TABLE 4 Resin compositions and characteristics (without solvent, catalyst and azeotropic carrier) according to the invention and comparison test Test according to the Comparison test 2 invention (example 2) Phthalic anhydride 418 390 Glycerol 15 Neopentyl glycol 343 340 Trimethylol propane 77 Adipic acid 162 171 BEPD 84 (Butyl ethyl propanediol) TOTAL 1000 1000 Hydroxyl index 55 60 (mg KOH/g) (ISO 2554 method) Acid index 4 1.5 (mg KOH/g) (ISO 2114 method) Solids content (%) 65.5 75.7 (ISO 3251 method) Calculated Mn 1760 1685 Brookfield viscosity at 25 C. 3500 5800 (mPa .Math. s) (ISO 3219 method) at the solids content indicated

3) Preparation of the Resin for Backer Coating

3.1) Raw Materials Used

[0073]

TABLE-US-00005 TABLE 5 Raw materials used Typical Nature of the composition Chemical Technical function/ according to Trade name name Supplier function functionality the invention PAN Phthalic Polynt Monomer Carboxyl/2 Diacid b1) anhydride AA Adipic acid Bayer Monomer Carboxyl/2 Diacid b2) EG Ethylene Dow Monomer Hydroxyl/2 Diol a3) glycol NPG Neopentyl Perstorp Monomer Hydroxyl/2 Diol a2) glycol BEPD Butyl ethyl Perstorp Monomer Hydroxyl/2 Diol a1) propanediol TMP Trimethylol Perstorp Monomer Hydroxyl/3 Polyol a4) propane Solvarex 9 Aromatic C.sub.9 Total Solvent for the Solvent for the solvent resin resin (fraction) BG Butyl glycol Brenntag Solvent for the Solvent for the resin resin Fascat Tin PMC Catalyst Catalyst 4100 monobutyl Organometallix oxide Xylene Xylene Total Azeotropic Azeotropic carrier solvent carrier solvent
3.2) Procedure for Resin Preparation: According to the Invention (Example 3) and Comparison Test 3 without BEPD

[0074] The procedure used is identical to that described in point 1.2) (The proportions are given in Table 6).

[0075] The resin according to the invention (example 3) is diluted in pure Solvarex 9 and in a Solvarex 9/butylglycol mixture (70/30) for the resin of comparison test 3.

TABLE-US-00006 TABLE 6 Compositions and characteristics of the resins (without solvent, catalyst and azeotropic carrier) according to the invention (example 3) and comparison test 3 Test according to the Comparison test 3 invention (example 3) Phthalic anhydride 370 368 Ethylene glycol 48 Neopentyl glycol 278 240 Trimethylol propane 219 99 Adipic acid 133 140 BEPD 105 (Butyl ethyl propanediol) TOTAL 1000 1000 Hydroxyl index 150 154 (mg KOH/g) (ISO 2554 method) Acid index 6 4 (mg KOH/g) (ISO 2114 method) Solids content (%) 67.5 76 (ISO 3251 method) Brookfield viscosity at 25 C. 3800 4100 (mPa .Math. s) (ISO 3219 method) at the solids content indicated Calculated Mn 700 660

4) Application of Resins in Paints for Metal Foil

4.1) Metal Foil and Application Conditions for the Coating/Packaging Before Tests

[0076] The sheeting used for the tests is galvanized steel sheeting 0.75 millimetres thick, pretreated with a solution of chromate.

[0077] The paint is applied using a Bar Coater applicator. Three types of application are made: [0078] primer coating, [0079] top-coat coating, [0080] backer coating.

[0081] The thickness of the top-coat coating and the backer coating on the metal sheeting is 20 m.

[0082] In the case of the top-coat coating, the paint is applied on a metal sheeting coated with a primer coating 5 m thick.

[0083] The resulting coated sheeting is put in a ventilated oven.

[0084] Table 7 below gives the crosslinking conditions depending on the type of coating, at 385 C.

TABLE-US-00007 TABLE 7 crosslinking conditions Peak T ( C.) on the Oven T ( C.) metal Duration (s) Primer 360 224 60 Top Coat 385 232 52 Backer 385 232 52

[0085] The paint, as a primer coating and backer coating on the metal and applied on primer coating as a top-coat coating, is evaluated through the following performance tests, after packaging the test panels in an air-conditioned room at 23 C.2 C. where the humidity is controlled at 50%5%.

TABLE-US-00008 Resistance to methyl ethyl ketone (in s) See description below or to methyl isobutyl ketone (in s) Charge 1 kg (MEK) or 500 g (MIBK)/ linear Taber Indentation test (mm) NF EN ISO 1520 Adhesion test NF EN ISO 2409 Adhesion + NF EN 13523-6 6 mm indentation Adhesion + 6 mm indentation + NF EN 13523-6 30 min at 90 C. T-Bend Test NF EN 13523-7 PERSOZ hardness (s) NF EN ISO 1522 Yield (g/m.sup.2) See formula below Yield gain (%)

[0086] The method for resistance to the solvent indicated consists in making back and forth movements on the coated sheeting with a Taber abraser device impregnated with said solvent and noting the time (in s) after which degradation in the coating is observed.

[0087] The yield is calculated according to the following formula from the dry paint density, the solids content and the coat thickness:

[0088] Yield (In g/m.sup.2)=100 multiplied by dry paint density (g/m.sup.3) multiplied by the thickness of the coat of paint (m) and the result divided by the solids content of the paint (%).

[0089] The covering power (in m.sup.2/g/) is equal to the Inverse of the yield (in g/m.sup.2) divided by the thickness of the coat.

[0090] Yield (in g/m.sup.2)=100 multiplied by dry paint density (g/m.sup.3) multiplied by the thickness of the coat of paint (m) and the result divided by the solids content of the paint (%).

4.2) Formulation and Preparation of a Paint for Primer Coats

[0091]

TABLE-US-00009 TABLE 8 Formulation of the paint Function Supplier Chemical name Resin in solvent 266 (1) Binder tested see point 1.2) Polyester (according to the and Table 2) invention example 1 or comparison 1) Solvarex 10 LN 38 (2) Solvent Total Aromatic hydrocarbon BUTYLDIGLYCOL 38 (3) Solvent Brenntag Ether alcohol DISPERBYK 161 5 (4) Dispersant BYK Block polymer KRONOS 2360 81 (5) Pigment KRONOS Titanium oxide BAYFERROX 5.5 (6) Pigment BAYER/ Iron oxide LANXESS SHIELDEX C 303 36 (7) Anticorrosive GRACE Silica pigment K-WHITE G 105 36 (8) Anticorrosive TAYCA Aluminum triphosphate pigment POLSPERSE 10 53 (9) Filler IMERYS Kaolin Aerosil R 972 10 (10) Rheological EVONIK Silica additive Resin in solvent 247 (11) Binder tested see point 1.2) Polyester (according to the and Table 2) invention example 1 and comparison 1) CYMEL 303 LF 50.5 (12) Crosslinker ALLNEX Melamine APTS (12.5% 7.9 (13) Catalyst BASF Para-toluenesulfonic acid butanol w/w) Solvarex 10 LN 59.5 (14) Solvent Total Aromatic C.sub.10 hydrocarbon (fraction) BUTYLDIGLYCOL 59.5 (15) Solvent Brenntag Ether alcool EPIKOTE 828 7.3 (16) Binder Dow Epoxy resin TOTAL 1000

[0092] In a 1 liter thermostated beaker at ambient temperature, in this order, the compounds (1), (2), (3), (4), (5), (6), (7), (8), (9) and (10) are added. This mixture is stirred using a Dispermat stirrer, then dispersed for 30 minutes at 3500 rpm in the presence of glass beads to facilitate pigment dispersion. After removing the beads for sieving, with stirring at 1000 rpm, the rest of the binder (11) and compounds (12), (13) and (16) are added. Still with stirring at 1000 rpm, the viscosity of the paint is adjusted due to the addition of (14) and (15).

[0093] The satin paint obtained presents the following characteristics (Table 9).

TABLE-US-00010 TABLE 9 Characteristics of the paint Density (g/cm.sup.3) 1.23 Solid by weight (%) 57.9 (Comparison 1) 64.5 (Invention example 1) VOC (g/L) 497 (Comparison 1) 428 (Invention example 1) PVC (%) 18 Cone/plane viscosity at 25 C. (m .Math. Pas) 410 (Comparison 1) 400 (Invention example 1) VOC: Volatile organic compounds PVC: Pigment Volume Concentration

4.2.1) Application Results: Mechanical Properties

[0094]

TABLE-US-00011 TABLE 10 Application results Comparison 1 Invention exemple1 Resistance to methyl isobutyl <5 <5 ketone (in s) Charge 500 g/linear Taber Adhesion test 0 0 Adhesion + 6 mm indentation 0 0 Adhesion + 6 mm indentation + 0 0 30 min at 90 C. T-Bend Test 1.5 T 1 T PERSOZ hardness (s) 280 200 Yield (g/m.sup.2) 13.2 11.5 Covering power (m.sup.2/kg/) 370 420 Improvement in covering power 0 13.5

4.3) Formulation and Preparation of a Top-Coat Coating Paint and a Backer Coating Paint

[0095]

TABLE-US-00012 TABLE 11 List of ingredients for a binder with tested solids content adjusted to a solids content of 65% with respective solvents described above, for resins according to invention, examples 2 and 3, and according to comparison tests 2 and 3 Function Supplier Chemical name Resin according to 183.5 (1) Binder tested see points 2.2) Polyester invention example 2 or and 3.2) example 3 or comparison 2 or 3 (solids content adjusted to 65%) Solvarex 10 LN 12 (2) Solvent Total Aromatic C.sub.10 hydrocarbon (fraction) BUTYLDIGLYCOL 12 (3) Solvent Brenntag Ether alcohol DISPERBYK 161 7.5 (4) Dispersant BYK Block polymer KRONOS 2360 298 (5) Pigment KRONOS Titanium oxide Aerosil R 972 2.5 (8) Rheological EVONIK Silica additive Resin (solids content 260 (7) Binder tested see points 2.2) Polyester 65%) and 3.2) Butyldiglycol 8.5 (8) Solvent Brenntag Ether alcohol Solvarex 10 LN 8.5 (9) Solvent Total Aromatic C.sub.10 hydrocarbon (fraction) Syloid ED 40 34 (10) Filler GRACE Silica CYMEL 303 LF 56 (11) Crosslinker ALLNEX Melamine APTS 8.7 (12) Catalyst BASF Para-toluenesulfonic (12.5% butanol w/w) acid Solvarex 10 LN 53 (13) Solvent Total Aromatic hydrocarbon BUTYLDIGLYCOL 53 (14) Solvent Brenntag Ether alcohol Crayvallac FLow 200 2 (15) Spreading Arkema Polyester agent TOTAL 1000

[0096] In a 1 liter thermostated beaker at ambient temperature, in this order, the compounds (1), (2), (3), (4), (5), (6) are added. This mixture is stirred using a Dispermat stirrer, then dispersed for 40 minutes at 3500 rpm. The rest of the binder (7), a part of the solvent (8) and (9) and the compound (10) are then added. Dispersion is continued for 15 minutes at 2500 rpm. Still with stirring at 1000 rpm, compounds (11) and (12) are added. The viscosity of the paint is adjusted due to the addition of solvents (13) and (14). At the end of the cycle, still with stirring at 1000 rpm, compound (15) is added.

[0097] The top-coat coating is evaluated, being applied to a mechanical sheeting previously coated with a primer coating similar to that described in point 4.2).

[0098] The semi-gloss paint obtained presents the following characteristics (Table 12).

TABLE-US-00013 TABLE 12 Characteristics of the semi-gloss paint for top-coat coating Cone/plane viscosity at Solids content (%) VOC (g/L) 25 C. (m .Math. Pas) Density PVC Comparison Invention Comparison Invention Comparison Invention (g/cm.sup.3) (%) 2 example 2 2 example 2 2 example 2 1.34 23 64.7 70.5 462 400 535 540

TABLE-US-00014 TABLE 13 Characteristics of the semi-gloss paint for backer coating Cone/plane viscosity at Solids content (%) VOC (g/L) 25 C. (m .Math. Pas) Density PVC Comparison Invention Comparison Invention Comparison Invention (g/cm.sup.3) (%) 3 example 3 3 example 3 3 example 3 1.34 23 65.3 72.2 457 386 530 525 VOC: Volatile organic compounds PVC: Pigment Volume Concentration

4.3.1) Application Results: Mechanical Properties

[0099]

TABLE-US-00015 TABLE 14 Application results Top-coat coating Backer coating Invention Invention Comparison 2 example 2 Comparison 3 example 3 Resistance to methyl >240 >240 >240 s 120 s 10 ethyl ketone (in s) Charge 1 kg/linear Taber Indentation test (mm) 11.4 11.2 7.4 10.2 Adhesion test 0 0 0 0 Adhesion + 0 0 2 0 6 mm indentation Adhesion + 6 mm 0 0 5 2-3 indentation + 30 min at 90 C. T-Bend Test 2.5 T 2 T 4 T 3.5 T PERSOZ hardness (s) 223 187 267 242 Yield (g/m.sup.2) 53.8 46.5 53.9 48.5 Covering power 372 430 371 413 (m.sup.2/kg/) Improvement in covering 0 16 0 11 power (%)