PEROXIDE-FREE COATING COMPOSITIONS COMPRISING UNSATURATED POLYESTER

Abstract

Disclosed herein is a coating composition including at least one unsaturated polyester (A) including units of formula a reactive diluent (B) including at least one polymerizable compound (B1), at least one catalyst (C), optionally at least one actinic radiation-activatable polymerization initiator (D), optionally at least one solvent (E), optionally at least one coating composition additive (F), and optionally at least one polymer (G) different from the unsaturated polyester (A), with the proviso that the coating composition does not include any peroxide. Also disclosed herein are substrates coated with the coating composition, a process for the preparation of the coated substrates, and compositions including at least one unsaturated polyester (A) including units of formula a reactive diluent (B) including at least one polymerizable compound (B1), at least one catalyst (C), and and optionally at least one solvent (E).

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Claims

1. A coating composition comprising: at least one unsaturated polyester (A) comprising units of formula ##STR00012## a reactive diluent (B) comprising at least one polymerizable compound (B1), at least one catalyst (C), optionally at least one actinic radiation-activatable polymerization initiator (D), optionally at least one solvent (E), optionally at least one coating composition additive (F), and optionally at least one polymer (G) different from the unsaturated polyester (A), with the proviso that the coating composition does not comprise any peroxide.

2. The coating composition of claim 1 wherein the unsaturated polyester (A) comprises units of formula ##STR00013## units of formula ##STR00014## optionally units derived from at least one dicarboxylic acid carrying at least one olefinically unsaturated group or derivative thereof, different from the units of formula (1) or (2), and units derived from at least one diol.

3. The coating composition of claim 2, wherein the molar ratio of units of formula (1) to the sum of units of formulae (1) and (2) is in the range of 50 to 99%.

4. The coating composition of claim 2, wherein the molar ratio of units of formula (1) to the sum of units of formula (1), units of formula (2) and units derived from at least one dicarboxylic acid carrying at least one olefinically unsaturated group or derivative thereof different from the units of formula (1) and (2), is the range of 50 to 90%.

5. The coating composition of claim 2, wherein the units derived from at least one dicarboxylic acid carrying at least one olefinically unsaturated group or derivative different from the units of formulae (1) and (2) comprise units of formula ##STR00015##

6. The composition of claim 2, wherein the diol is a diol carrying no olefinically unsaturated groups.

7. The coating composition of claim 1, wherein the reactive diluent (B) consists of compounds carrying at least one (meth)acryloyl group.

8. The coating composition of claim 1 wherein the polymerizable compound (B1) is selected from the group consisting of diethyleneglycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetrathylene glycol di(methacrylate), dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate and tetrapropylene glycol di(meth)acrylate.

9. The coating composition of claim 8, wherein the polymerizable compound (B1) is dipropylene glycol diacrylate.

10. The coating composition of claim 9, wherein the weight ratio of the polymerizable compound (B1) to the reactive diluent (B) is at least 40%.

11. The coating composition of claim 1, wherein the catalyst (C) is a metal salt or a metal complex, wherein the metal is cobalt or iron.

12. The composition of claim 11, wherein the metal is cobalt.

13. The coating composition of claim 12, which comprises at least one actinic radiation activatable polymerization initiator (D).

14. The coating composition of claim 13, wherein the actinic radiation activatable polymerization initiator (D) is a UV radiation-activatable polymerization initiator.

15. A composition consisting of: at least one unsaturated polyester (A) comprising units of formula ##STR00016## a reactive diluent (B) comprising at least one polymerizable compound (B1), at least one catalyst (C), and optionally at least one solvent (E).

16. A method of using a composition consisting of: at least one unsaturated polyester (A) comprising units of formula ##STR00017## a reactive diluent (B) comprising at least one polymerizable compound (B1), at least one catalyst (C), and optionally at least one solvent (E), the method comprising using the composition in the coating composition of claim 1.

17. A substrate coated with the coating composition of claim 1.

18. The substrate of claim 17, wherein the substrate is a wood-based substrate.

19. A process for preparing the substrate of claim 17, the process comprising the steps of (i) applying the coating composition to a substrate to form a layer and (ii) treating the layer formed in step (i) with actinic radiation or electron beam.

20. The process of claim 19, wherein the substrate is a wood-based substrate.

Description

EXAMPLES

Abbreviations

[0202] DPGDA is dipropylene glycol diacrylate, GPTA is glycerol propoxylated triacrylate (average 3.8 propylene oxide units per molecule), CHMA is cyclohexyl methacrylate, HDDA is hexane-1,6-diol diacrylate, NMA is 2-norbornyl methacrylate, Omnirad 184 is 1-hydroxycyclohexyl phenyl ketone), Pergaquick C60X is 6% solution of cobalt bis(2-ethyl-hexanoate) in 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, Nouryact CF40 comprises an iron complex.

Example 1

Preparation of a Mixture of an Unsaturated Polyester (A1) Comprising Units of Formulae (1), (2) and (3), and Dipropylene Glycol Diacrylate (DPGDA) as a Polymerizable Compound

[0203] 1.44 weight parts diethylene glycol (MW 106.12 g/mol, 1.36 mol parts), 1 weight parts maleic anhydride (MW 98.06 g/mol, 1.02 mol parts) and 0.57 weight parts 1,2,3,6-tetrahydrophthalic anhydride (MW 152.15 g/mol, 0.37 mol parts) were reacted first at temperatures from 140 to 200° C., and later at 220° C. until the desired molecular weight was reached. The water formed during the esterification was removed by distillation. Under the reaction conditions (220° C.) the maleic acid derived units partially isomerized to fumaric acid derived units. The reaction mixture was cooled to temperatures below 130° C. and diluted with dipropylene glycol diacrylate to yield a mixture comprising 55 weight % of an unsaturated polyester (A1) and 45 weight % DPGDA based on the weight of the mixture.

[0204] The molar ratio of the units of formula (1)/units of formula (2)/units of formula (3) in the unsaturated polyester (A1) is 2.48/0.27/1.00 (determined by .sup.1H-NMR), the Mw of the unsaturated polyester (A1) is 4279 g/mol and the Mn is 892 g/mol.

Example 2

Preparation of a Mixture of an Unsaturated Polyester (A1) Comprising Units of Formulae (1), (2) and (3), and Glycerol Propoxylated Triacrylate as Polymerizable Compound (Average 3.8 PO Units Per Molecule, MW 475 g/mol)

[0205] 1.44 weight parts diethylene glycol (MW 106.12 g/mol, 1.36 mol parts), 1 weight parts maleic anhydride (MW 98.06 g/mol, 1.02 mol parts) and 0.57 weight parts 1,2,3,6-tetrahydrophthalic anhydride (MW 152.15 g/mol, 0.37 mol parts) were reacted first at temperatures from 140 to 200° C., and later at 220° C. until the desired molecular weight was reached. The water formed during the esterification was removed by distillation. Under the reaction conditions (220° C.) the maleic acid derived units partially isomerized to fumaric acid derived units. The reaction mixture was cooled to temperatures below 130° C. and diluted with glycerol propoxylated triacrylate (average 3.8 PO units per molecule, MW 475 g/mol) to yield a mixture comprising 40 weight % of a polyolefinically unsaturated polyester (A1) and 60 weight % glycerol propoxylated triacrylate (average 3.8 PO units per molecule, MW 475 g/mol) based on the weight of the mixture.

[0206] The molar ratio of the units of formula (1)/units of formula (2)/units of formula (3) in the unsaturated polyester (A1) is 2.48/0.27/1.00 (determined by .sup.1H-NMR), the Mw of unsaturated polyester (A1) is 4279 g/mol and the Mn is 892 g/mol.

Example 3

Preparation of a Coating Composition Comprising the Mixture of Example 1

[0207] 75 g of the mixture of example 1, 25 g dipropyleneglycol diacrylate, 4 g Omnirad 184 and 1 g Pergaquick C60X were mixed at room temperature to yield a coating composition.

[0208] Examples 4 to 11

Preparation of Coating Compositions Comprising the Mixture of Example 1

[0209] Coating compositions comprising the mixture of example 1 were prepared in analogy to example 3, but with the ingredients listed in table 1.

TABLE-US-00001 TABLE 1 Amounts ingredients [g] ingredients Ex 3 Ex4 Ex 5 Ex 6 Ex 7 Ex 8 Ex 9 Ex 10 Ex 11 mixture Example 1 75 75 75 75 75 75 75 75 75 DPGDA 25 GPTA 25 25 CHMA 25 25 HDDA 25 25 NMA 25 25 Omnirad 184 4 4 4 4 4 4 4 4 4 PergaQuick C60X 1 1 1 1 1 Nouryact CF40 1 1 1 1

Comparative Examples 1 to 5

Preparation of a Coating Compositions Comprising the Mixture of Example 1, but No Catalyst

[0210] Comparative coating compositions comprising the mixture of example 1 were prepared in analogy to example 3, but with the ingredients listed in table 2.

TABLE-US-00002 TABLE 2 Amounts ingredients [g] ingredients CEx 1 CEx 2 CEx 3 CEx 4 CEx 5 mixture Example 1 75 75 75 75 75 DPGDA 25 GPTA 25 CHMA 25 HDDA 25 NMA 25 Omnirad 184 4 4 4 4 4 PergaQuick C60X Nouryact CF40

Comparative Examples 6 to 9

Preparation of a Coating Compositions Comprising Laromer® PE9074 and Laromer® PE8800, Respectively

[0211] Comparative coating composition comprising Laromer® PE9074 and Laromer® PE8800, respectively, were prepared in analogy to example 3, but with the ingredients listed in table 3.

[0212] Laromer® PE9074 comprises a polyester having no olefinically unsaturated units in the main chain of the polyester but carrying acrylic acid-derived groups in the side chains of the polyester, and reactive diluent.

[0213] Laromer® PE8800 comprises a polyester having maleic acid-derived units in the main chain of the polyester and carrying acrylic acid-derived groups in the side chains of the polyester, and a reactive diluent.

TABLE-US-00003 TABLE 3 Amount ingredients [g] ingredients CEx 6 CEx 7 CEx 8 CEx 9 Laromer ® PE9074 75 75 Laromer ® PE8800 75 75 DPGDA GPTA 25 25 25 25 Omnirad 184 4 4 4 4 PergaQuick C60X 1 1 Nouryact CF40 1 1

Example 12

Determination of the Amount of Dipropylene Glycol Diacrylate (DPGDA) Extractable from UV-irradiated Veneered Oak Substrates Coated with of the Coating Compositions of Example 3 and of Comparative Example 1, Respectively

[0214] The coating composition of example 3 and comparative example 1, respectively, was applied with a roller coater BKL Bürkle on veneered oak substrates having a size (length×width) of 10 cm.sup.2 with a quantity of 40 g coating composition/m.sup.2 veneered oak substrate. 1 Minute after application the coated substrates were irradiated using medium pressure Hg lamp with a power of 160 W/cm and a conveyer belt speed of 10 m/min.

[0215] After UV irradiation, the coated veneered oak substrates were kept in the dark at room temperature. DPGDA was extracted from the coated veneered oak substrates using acetone (80° C., 1.5 h) according to IKEA IOS™ 0002 directly after UV-irradiation and after 4, 10 and 22, respectively, weeks after UV-irradiation. The amount of extractable DPGDA was determined by gas chromatography.

TABLE-US-00004 TABLE 4 Amount of extractable DPGDA [mg/m.sup.2] Week Ex 3 CEx 1 0 11000 10900 4 1350 7250 10 1100 7185 22 400 2950

[0216] Table 4 shows that the amount of DPGDA extractable from veneered oak substrates coated with coating composition of example 3 comprising unsaturated polyester A1, DPGDA, UV-radiation curable polymerization initiator Omnirad 184 and catalyst PergaQuick C60X decreases over a period of 22 weeks following UV irradiation from 11000 mg/m.sup.2 to only 400 mg/m.sup.2, whereas the amount of DPGDA extractable from veneered oak substrates coated with the coating composition of comparative example 1 comprising unsaturated polyester Al, DPGDA, UV-radiation curable polymerization initiator Omnirad 184 but no catalyst PergaQuick C60X only decreases over a period of 22 weeks following UV-irradition from 10900 mg/m.sup.2 to 2950 mg/m.sup.2.

[0217] As only not-reacted DPGDA can be extracted from the coated substrates, a decrease in the amount of extractable DPGDA over a period of 22 weeks following UV irradiation shows that DPGDA in the coated substrate continues to react over a period of 22 weeks following UV irradiation.

[0218] Thus, the amount of not-reacted DPGDA of veneered oak substrates coated with the coating composition of example 3 can conveniently be decreased by simply storing the coated substrates after UV irradiation for a period of 22 weeks.

Example 13

Determination of the Amount of the Polymerizable Compounds (DPGDA, GPTA, CHMA, HDDA and NMA) Extractable from UV-irradiated Veneered Oak Substrates Coated with of the Coating Composition of Example 3, 6, 7, 8 and 10, Respectively

[0219] The coating composition of examples 3, 6, 7, 8, and 10, respectively, was applied with a roller coater BKL Bürkle on veneered oak substrates having a size (length×width) of 10 cm.sup.2 with a quantity of 27 g coating composition/m.sup.2 veneered oak substrate and 1 minute after application irradiated using medium pressure Hg lamp with a power of 120 W/cm and a conveyer belt speed of 5 m/min. After UV irradiation, the coated veneered oak substrates were kept in the dark at room temperature. The polymerizable compounds (DPGDA, CHMA, HDDA and NMA) were extracted from the coated veneered oak substrates using acetone (80° C., 1.5 h) according to IKEA IOS™ 0002 directly after UV-radiation and after 8, 12 and 20, respectively, weeks after UV-irradiation. The amount of extractable polymerizable compounds (DPGDA, CHMA, HDDA and NMA) was determined by gas chromatography.

TABLE-US-00005 TABLE 5 Amount extractable Polymerizable Compound [mg/m.sup.2] Ex 3 Ex 6 Ex 7 EX8 Ex 10 Week DPGDA CHMA DPGDA CHMA DPGDA HDDA DPGDA NMA DPGDA 0 6700 3800 5000 5400 6700 4200 6100 4500 5100 8 475 120 710 <50 2350 210 295 240 780 12 460 107 660 <50 2150 210 270 225 740 20 460 107 580 <50 1300 nd nd 120 700

[0220] Table 5 shows that the amount of all polymerizable compounds (DPGDA, CHMA, HDDA and NMA, respectively) extractable from veneered oak substrates coated with coating composition of example 3, 6, 7, 8 and 10 comprising unsaturated polyester A1, at least one polymerizable compound, UV-curable initiator Omnirad 184 and catalyst PergaQuick C60X or Nouryact CF40 decrease over a period of 20 weeks following UV irradiation,

[0221] As only not-reacted polymerizable compounds (DPGDA, CHMA, HDDA and NMA, respectively) can be extracted from the coated substrates, a decrease in the amount of extractable polymerizable compounds over a period of 20 weeks following UV irradiation shows that the polymerizable compound in the coated substrate continues to react over a period of 20 weeks following UV irradiation.

[0222] Thus, the amount of not-reacted polymerizable compound (DPGDA, CHMA, HDDA and NMA, respectively) of veneered oak substrates coated with the coating composition of example 3, 6, 7, 8 and 10 can conveniently be decreased by simply storing the coated substrates after UV radiation for a period of 20 weeks.

Example 14

Analysis of the Curing Behaviour of Samples of the Coating Compositions of Examples 3 to 11 and of Comparative Examples 1 to 9 in an Open Metal Sheet Lid without Applying Actinic Radiation or Electron Beam

[0223] 2 g of the liquid coating compositions of examples 3 to 11 and of comparative examples 1 to 9, respectively, was placed in a sheet metal lid having a diameter of 4 cm. The “sheet metal lid with the samples of the coating composition was kept “open” at room temperature in the dark. The curing behavior of the samples of the coating composition was monitored by weekly inspecting with a spatula whether the core of the sample of coating composition in the sheet metal lid is solid or liquid. After 36 weeks the test was stopped. The time period in weeks the core of the samples of coating composition of examples 1 to 11 in the sheet metal lid needed to become solid is shown in table 6. The cores of the samples of the coating compositions of comparative examples 1 to 9 were still liquid after 36 weeks.

TABLE-US-00006 TABLE 6 Coating composition Ex 3 Ex4 Ex 5 Ex 6 Ex 7 Ex 8 Ex 9 Ex 10 Ex 11 Time period the 8 14 15 11 11 17 11 8 15 core of the sample needs to become solid [weeks]

[0224] Table 6 shows that the core of the samples of the coating compositions of examples 3 to 11 in the sheet metal lid become solid after a time period of between 8 and 17 weeks. It is stipulated that that the polymerizable compounds of the coating composition of the present invention react and crosslink to the unsaturated polyester molecules (A) by oxygen-initiated mechanism upon storage.

Example 15

Determination of the Pendulum Hardness of UV-irradiated Layers of the Coating Compositions of Examples 3, 4 and 8 and of Comparative Examples 1, 2, 4, 6, 7, 8 and 9

[0225] The coating composition of examples 3, 4 and 8 and of comparative examples 1, 2, 4, 6, 7, 8 and 9, respectively, was applied with a bar on a glass substrate (thickness of wet layer: 400 μm) and irradiated using a medium pressure Hg lamp with a power of 120 W/cm and a conveyer belt speed of 10 m/min. After UV irradiation, the coated glass substrates were kept at room temperature in the dark and the pendulum hardness was determined directly after UV curing and after the weeks indicated in tables 7 and 8 using DIN EN ISO 1522 (04-2007).

[0226] The pendulum hardness of the UV-irradiated layers of the coating compositions of examples 3 and comparative example 1 can be seen in table 7.

TABLE-US-00007 TABLE 7 Pendulum Hardness [number of oscillations] Week Ex 3 CEx 1 0 47 50 1 58 55 2 64 54 4 74 54 8 84 56 10 95 58 18 98 56

[0227] Table 7 shows that the pendulum hardness of the UV-irradiated layer of the coating compositions of examples 3 comprising unsaturated polyester A1, DPGDA, UV-radiation curable polymerization initiator Omnirad 184 and catalyst PergaQuick C60X increase over a period of 18 weeks following UV irradiation from 47 to 98 oscillations, whereas the pendulum hardness of the UV-irradiated layer of the coating compositions of comparative example 1 comprising unsaturated polyester A1, DPGDA, UV-radiation curable polymerization initiator Omnirad 184 but no catalyst PergaQuick C60X only increase over a period of 26 weeks following UV-irradition from 50 to 56 oscillations.

[0228] The pendulum hardness of the UV-irradiated layers of the coating compositions s of examples of examples 4 and 8 and comparative examples 2, 4, 6, 7, 8 and 9 can be seen in table 8.

TABLE-US-00008 TABLE 8 Pendulum Hardness [number of oscillations] Week Ex4 Ex 8 CEx 2 CEx 4 CEx 6 CEx 7 CEx 8 CEx 9 0 39 48 42 50 21 21 61 63 6 69 82 39 55 20 21 64 70 8 72 88 44 55 20 21 62 69 10 76 89 45 55 20 21 63 70 12 78 89 45 54 19 20 64 71 16 83 93 46 55 20 21 64 70 20 87 97 51 54 21 21 63 70 26 91 99 54 55 23 24 65 58

[0229] Table 8 shows that the pendulum hardness of the UV-irradiated layer of the coating compositions of examples 4 comprising unsaturated polyester A1, DPGDA, GPTA, UV-radiation curable polymerization initiator Omnirad 184 and catalyst PergaQuick C60X increase over a period of 26 weeks following UV irradiation from 38 to 91 oscillations, whereas the pendulum hardness of the UV-irradiated layer of the coating compositions of comparative example 2 comprising unsaturated polyester A1, DPGDA, GPTA, UV-radiation curable polymerization initiator Omnirad 184 but no catalyst PergaQuick C60X only increase over a period of 26 weeks following UV-irradition from 42 to 54 oscillations.

[0230] Table 8 also shows that the pendulum hardness of the UV-irradiated layer of the coating compositions of examples 8 comprising unsaturated polyester A1, DPGDA, HDDA, UV-radiation curable polymerization initiator Omnirad 184 and catalyst PergaQuick C60X increase over a period of 26 weeks following UV irradiation from 48 to 99 oscillations, whereas the pendulum hardness of the UV-irradiated layer of the coating compositions of comparative example 4 comprising unsaturated polyester A1, DPGDA, HDDA, UV-radiation curable polymerization initiator Omnirad 184 but no catalyst PergaQuick C60X only increase over a period of 26 weeks following UV-irradition from 50 to 55 oscillations.

[0231] Table 8 also shows that the pendulum hardness of the UV-irradiated layer of the coating compositions of comparative examples 6 to 9 comprising no unsaturated polyester comprising units of formula (1) show almost no increase in pendulum hardness over a period of 26 weeks.

Example 16

Determination of the Indentation Hardness [N/mm.SUP.2.] of the UV-irradiated Layers of the Coating Compositions of Example 3 and of Comparative Example 1

[0232] The coating composition of example 3 and of comparative example 1, respectively, was applied with a bar on a glass substrate (thickness of wet layer: 400 μm) and irradiated using a medium pressure Hg lamp with a power of 120 W/cm and a conveyer belt speed of 10 m/min. The glass substrate coated with the UV-cured layer was kept at room temperature in the dark and the indentation hardness was determined directly after UV radiation treatment and 1, 2, 4, 8, 10, 14, 35 18, 22, 30 and 32 weeks after UV irradiation using DIN EN ISO 14577-1 (2000).

[0233] The results are shown in table 9

TABLE-US-00009 TABLE 9 Indentation hardness [N/mm.sup.2] Week Ex 3 CEx 1 0 122 134 1 181 156 2 204 158 4 241 161 8 267 167 10 281 178 14 265 164 18 268 163 22 264 156

[0234] Table 9 shows that the indentation hardness of the UV-irradiated layer of the coating composition of example 3 comprising unsaturated polyester A1, DPGDA, UV-radiation curable polymerization initiator Omnirad 184 and catalyst PergaQuick C60X increase over a period of 22 weeks following UV irradiation from 122 to 264 N/mm.sup.2, whereas the indentation hardness of the UV-irradiated layer of the coating composition of comparative example 1 comprising unsaturated polyester A1, DPGDA, UV-radiation curable polymerization initiator Omnirad 184 but no catalyst PergaQuick C60X only increase over a period of 22 weeks following UV-irradition from 134 to 156 N/mm.sup.2.

Example 15

Determination of the Viscosity of the Coating Composition of Examples 3 and Comparative Example 1 When Stored in a Closed Container at Room Temperature

[0235] The coating composition of example 3 and of comparative example 1 were stored in a closed container at room temperature, and the viscosity of the coating compositions were measured at 23° C. using DIN EN ISO 2555 (2018) after the weeks indicated in table 10.

[0236] The results are shown in table 10.

TABLE-US-00010 TABLE 10 Viscosity [mPa × s] Week Ex 3 CEx 1 0 830 840 1 800 830 2 780 820 4 800 830 8 820 820 12 810 830 16 790 760 20 760 730 24 740 720 28 720 710 32 730 720 36 750 700

[0237] Table 10 shows that the viscosity of the liquid coating composition of example 3 comprising unsaturated polyester A1, DPGDA, UV-radiation curable polymerization initiator Omnirad 184 and catalyst PergaQuick C60X only slightly decreases when stored in a closed container over a period of 36 weeks from 830 to 750 mPa×s, and that the viscosity of the liquid coating composition of example 3 is comparable to the viscosity of the liquid coating composition of comparative example 1 comprising unsaturated polyester A1, DPGDA, UV-radiation curable polymerization initiator Omnirad 184 but no catalyst PergaQuick C60X.

[0238] Thus, the presence of catalyst PergaQuick C60X in the coating composition of example 3 does not influence the viscosity of the coating composition when stored in a closed container over a period of 36 weeks.