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GB2203155A - Curable coating agent - Google Patents

Curable coating agent Download PDF

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Publication number
GB2203155A
GB2203155A GB08804882A GB8804882A GB2203155A GB 2203155 A GB2203155 A GB 2203155A GB 08804882 A GB08804882 A GB 08804882A GB 8804882 A GB8804882 A GB 8804882A GB 2203155 A GB2203155 A GB 2203155A
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United Kingdom
Prior art keywords
coating agent
curable coating
agent according
mol
vinyl ethers
Prior art date
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Granted
Application number
GB08804882A
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GB2203155B (en
GB8804882D0 (en
Inventor
Manfred Priesch
Christian Weitemeyer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Evonik Operations GmbH
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TH Goldschmidt AG
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Publication of GB8804882D0 publication Critical patent/GB8804882D0/en
Publication of GB2203155A publication Critical patent/GB2203155A/en
Application granted granted Critical
Publication of GB2203155B publication Critical patent/GB2203155B/en
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    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D127/00Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers
    • C09D127/02Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
    • C09D127/12Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Organic Chemistry (AREA)
  • Paints Or Removers (AREA)

Abstract

A curable coating agent which has a high flexibility and good weathering resistance whilst retaining the original gloss comprises 20 to 100% by weight of a mixture of a) a copolymer containing 40 to 60 mol % of a fluoroolefin, 5 to 45 mol % of cyclohexyl vinyl ethers, 5 to 45 mol % of alkyl vinyl ethers and 3 to 15 mol % of hydroxyalkyl vinyl ethers and b) a hydroxysiloxane or alkoxysiloxane of the general formula <IMAGE> wherein R<1> is an alkyl radical having 1 to 4 carbon atoms or a phenyl radical, R<2> is a hydrogen radical or an alkyl radical having 1 to 4 carbon atoms, a = 1.0 to 2.2, b = 0.01 to 2.0, a + b</=3; and the ratio of OR<2> groups in the siloxane to hydroxy groups in the copolymer is 0.8 to 1.5; or c) partial reaction products thereof, which are still soluble in organic solvents. The coating agents are suitable for coating metal sheets by the coil-coating process. <IMAGE>

Description

Curabte coating agent The invention relates to a curable coating agent based on fluorine-containing copolymers carrying hydroxy groups.
French Patent Specification 2,488,260 has disclosed curable fluorinated copolymers which consist of 40 to 60 mol % of fluoroolefins, 5 to 45 mol % of cyclohexyl vinyl ethers, 5 to 45 mol % of alkyl vinyl ethers and 3 to 15 mol X of hydroxyalkyl vinyl ethers, the intrinsic viscosity of the comonoers being 0.05 to 2.0 C100 mLIg) in tetrahydrofuran at 300C. On account of their OH groups, these copolymers are reactive and can be cured by means of suitable crosslinking agents, such as melamine resins, urea resins, polybasic acids or polyisocyanates.
Such curable resin formulations can be used, for example, as finishing coats for a cement-based material, as is described in German Offenlegungsschrift 3,323,271.
In this Offenlegungsschrift, diisocyanates and titanium alkoxides are mentioned as crosslinking agents for the fluorocopolymers for curing at low temperatures, and melamine resins or urea resins as well as polycarboxylic acids are mentioned for curing at higher temperatures.
In German Offenlegungsschrift 3,405,607, a curable resin composition is described which contains a fluorinated copolymer of the type described above and a polymerizable compound. The polymerizable compound here comprises unsaturated compounds or epoxy groups. A crosslinking agent of the silicone type is also mentioned, inter alia, in this Offenlegungsschrift as a crosslinking agent, in addition to the abovementioned curing agents. More detailed data on the synthesis and structure of such a silicon crosslinking agent are not to be found in the Offenlegungsschrift.
In US Patent Specification 3,429,845, formulations are described which consist of copolymers of fluorinated monomers and hydroxylalkyl vinyl ethers on the one hand and polysilicic acids as crosslinking agents on the other hand. When these reactive formulations are cured on surfaces, coatings are obtained which are scratch-resistant but fairly brittle and highly crosslinked.
It is the object of the invention to provide curable coating agents based on fluorine-containing copolymers, which have a high flexibility and good weathering resistance while retaining the original gloss.
Surprisingly, -it has been found that curable coating agents have this combination of properties when, according to the invention, they consist of 20 to 100 Z by weight of a mixture of a) a copolymer containing 40 to 60 mol X of a fluoro olef in, 5 to 45 mol X of cyclohexyl vinyl ethers, 5 to 45 mol X of alkyl vinyl ethers and 3 to 15 mol Z of hydroxyalkyl vinyl ethers and b) a hydroxysiloxane or alkoxysiloxane of the general formula
wherein R1 is an alkyl radical having 1 to 4 carbon atoms or a phenyl radical, R2 is a hydrogen radical or an alkyl radical having 1 to 4 carbon atoms, a = 1.0 to 2.2, b = 0.01 to 2.0, and a + b ( 3, the siloxane being present in the mixture in such quantities that there are 0.8 to 1.5 OR2 groups of the siloxane for each hydroxyl group of the fluorine containing copolymer, or c) partial reaction products thereof, which are still soluble in organic solvents, O to 70 Z by weight of solvent, O to 70 X by weight of pigments and/or fillers and O to 2 X by weight of catalyst.
The fluorine-containing copolymers correspond to the fluorine-containing copolymers which are known from the state of the art and carry hydroxyl groups.
Tetrafluoroethylene, hexafluoropropylene and chl-orotrifluoroethylene are particularly suitable as monomeric fluoroolefins for the preparation of the copolymers.
The alkyl vinyl ethers and hydroxyalkyl vinyl ethers used for the copolymerization are especially those having 2 to 8 carbon atoms in the alkyl group. Hydroxybutyl vinyl ether is especially preferred as the hydroxyalkyl vinyl ether monomer. Possible compositions of these known reactive fluorocopolymers are to be found in the German Offenlegungsschriften 3,323,271 and 3,405,607, mentioned at the outset, and in French Patent Specification 2,488,260 and US Patent Specification 3,429,845.
The essential feature of the curable coating agent is its content of hydroxysiloxanes or alkoxysiloxanes of the general formula
R 1 can be a straight-chain or branched alkyl radical having 1 to 4 carbon atoms or a phenyl radical. Pre ferably, R1 is a methyl radical. Methyl radicals or phenyl radicals can also be present side by side in the average molecule.
R2 is a hydrogen radical or a straight-chain or branched alkyl radical having 1 to 4 carbon atoms, preferably the ethyl radical.
a indicates the number of hydrocarbon radicals bonded directly to the Si atom. a has a value from 1.0 to 2.2 and is preferably 1.0 to 1.6.
b characterizes the number of hydroxy radicals or alkoxy radicals on the Si atom. b is 0.01 to 2.0 and preferably 0.1 to 1.5.
The condition a + b < 3 must be fulfilled here.
Examples of suitable siloxanes of the formula I are:
Ph = phenyl radical
The composition by weight of the mixture of fluorine-containing copolymers a) and siloxanes b) is defined in such a way that there are 0.8 to 1.5, preferably 1.0 to 1.2, OR2 groups of the siloxane for one hydroxyl group of the fluorine-containing copolymer.
To adjust the desired processing viscosity, the coating agent can contain 0 to 70 X by weight of solvent.
Suitable solvents are ketones such as cyclohexanone, aromatics such as xylene, and esters such as butyl acetate.
The coating agent can contain 0 to 70 X by weight of pigments and/or fillers. Examples of such pigments are titanium dioxide, nickel titanium yellow, chromium titanium yellow, phthalocyanine blue and chromium oxide green.
The fillers employed can be the fillers conventionally used for coating agents, such as barium sulphate, aluminium silicate, calcium sulphate and silica.
The curable coating agent can contain 0 to 2 Z by weight of catalyst. Suitable catalysts are butyl titanate, isopropyl titanate, dibutyl-tin dilaurate and p-toluene sulphonic acid.
The fluorine-containing copolymers carrying hydroxyl groups can already be partially reacted with the siloxanes of the formula I before the final curing. For this purpose, the mixture is briefly heated to temperatures from 100 to 180C. A necessary condition in this case, however, is that the partial reaction products are still soluble in organic solvents. A degree of conversion of 70 %, which can be monitored, for example, by the quantity of the released alcohol R2OH, must therefore generally not be exceeded before the final curing.
The curing of the coating agent according to the invention takes place within a temperature range from 150 to 2500C. On curing, the (remaining) OR2 groups of the siloxane of the general formula I react with the hydroxyl groups of the fluorine-containing copolymer, with elimination of R2OH. This gives crosslinked products insoluble in organic soLvents.
In addition to a high flexibility, the curable coating agents according to the invention surprisingly have, as a result of the selection of the siloxanes of the formula I, the property that their gloss virtually does not diminish, or only insignificantly, even under long-term weathering. When fluoropolymers of the abovementioned type, crosslinked with polyisocyanates for example, are weathered, the gloss decreases during weathering. When starting, for instance, from a gloss retention of 60 X, this diminishes to about 36 Z under weathering for 2,000 hours. The curable fluoro-polymers crosslinked with melamine resins show similar behaviour.
In contrast thereto, the gloss retention of the coating agents according to the invention remains substantially the same even under long-term weathering. This behaviour cannot be derived additively from the properties of the reactants a) and b).
Due to their high flexibility, the curable coating agents according to the invention are suitable especially for coating metal sheets by the coil-coating process Such metal sheets can be used with particular advantage, for example, for the production of facade elements exposed to weathering.
In the following examples, curable coating agents of a composition according to the invention and the properties of the coatings formed from them by curing are shown in comparison with products of the state of the art.
Example 1 Preparation of coating agent A according to the invention 180 g of a fluorine-containing copolymer of a fluoroolefin, cyclohexyl vinyl ether, an alkyl vinyl ether and hydroxy butyl vinyl ether having an OH equivalent weight of 500 (commercially obtainable under the name Lumiflon 544 from Messrs. Asahi Glass Co.) in the form of a 40 Z by weight solution in xylene are heated to 1300C with 64 g of a siloxane of the formula
corresponding to a COH : SiOC2Hs ratio of 1 : 1.11, 135 g of cyclohexanone, 140 g of 1-methoxy-2-propanol and 0.5 g of tetrabutyl titanate. 55 g of distillate are obtained in the course of 20 minutes. The distillate contains 6.8 g of ethanol, corresponding to a conversion of 40.9 X. The solution obtained has a solids content of 32.5 X by weight.
100 g of the solution obtained are intimately mixed with 32 g of titanium dioxide pigment * and 20 g of butyldiglycol acetate, coating agent A being obtained.
= Kronos RN 59 Example 2 Preparation of coating agent B according to the invention 30 g of a fluorine-containing copolymer of a fluoroolef in, cyclohexyl vinyl ether, an alkyl vinyl ether and hydroxybutyl vinyl ether having an OH equivalent weight of 1,070 g (commercially obtainable under the name Lumiflon 200 from Messrs. Asahi Glass Co.) in the form of a 60 X by weight solution in xylene are intimately mixed with 5.5 g of a siloxane of the formula
corresponding to a COH : SiOCH3 ratio of 1 : 1.06, 15 g of titanium dioxide pigment+, 5 g of Solvesso 150 5 g of Solvesso 200+f+, 10 g of ethylglycol acetate and 0.1 g of tetrabutyl titanate, coating agent B being obtained.
Mixture of aromatic hydrocarbons having a boiling range of 184 to 2050C Mixture of aromatic hydrocarbons having a boiling range of 218 to 280 0C Example 3 Preparation of a coating agent C, not according to the invention, with hexamethoxymethylmelamine as the crosslinking agent 30 g of a fluorine-containing copolymer of a fluoro-olefin, cyclohexyl vinyl ether and hydroxybutyl vinyl ether having an OH equivalent weight of 1,070 (commercially obtainable under the name Lumiflon 200 from Messrs.Asahi Glass Co.) in the form of 60 x by weight solution in xylene are intimately mixed with 4 g of hexamethoxymethylmelamine, 15 g of titanium dioxide pigment 5 g of Solvesso 150 , 5 g of Solvesso 200 , 10 g of ethyl-glycol acetate and 0.3 g of a 50 % by weight solution of a latent curing agent based on p-toluenesulphonic acrid** 0, comparison coating agent C being obtained.
o = Vesturit SL 1203 Example 4 Preparation of a coating agent D, not according to the invention, with an isocyanate as the crosslinking agent 30 g of a fluorine-containing copolymer of a fluoroolefin, cyclohexyl vinyl ether, an alkyl vinyl ether and hydroxybutyl vinyl ether having an OH equivalent weight of 1,070 (commercially obtainable under the name Lumiflon 200 from Messrs. Asahi Glass Co.) in the form of a 60 % by weight solution in xylene are intimately mixed with 14 g of blocked isophorone diisocyanate oo, 15 g of titanium dioxide pigment*, 5 g of Solvesso 150 5 g of Solvesso 200*++, 10 g of ethylglycol acetate and 0.3 g of dibutyl-tin dilaurate, the comparison coating agent D being obtained.
** oo = IPDI adduct BL 1370 Application tests The coating agents are applied to chromatized alu minium sheets by means of a wire coater. The dry film thickness is 30 pm. The coating is baked at an oven temperature of 320 C, until the MEK value is > 200.
About 70 seconds are required for this purpose. This corresponds to a peak metal temperature of about 260 C.
A T bend value of 0.5 (ECCA standard) is obtained. The weathering is carried out in a QUV tester (Q Panel Co., Cleveland, Ohio, USA) in accordance with ASTM standard G 53 - 84, with 4 hours UV and 4 hours condensation.
The weathering behaviour can be seen from the table which follows, Table (600 gloss retention in X according to 6pardner) Duration (hours) 0 250 500 750 1000 1250 1500 1750 2000 Example 1 Sheet 1 61 77 76 73 74 77 76 74 75 Sheet 2 64 78 75 76 73 75 75 73 74 Example 2 Sheet 1 65 77 78 76 73 76 77 75 74 Sheet 2 62 78 80 78 76 76 77 73 74 Example 3 Sheet 1 63 71 73 69 64 65 51 40 32 Sheet 2 64 73 71 72 67 68 63 52 41 Example 4 Sheet 1 59 63 62 61 56 56 51 45 38 Sheet 2 58 64 62 60 54 54 50 45 36 The comparison of the weathering properties of the coating agents A and B according to the invention with the properties of the coating agents C and b not according to the invention shows that a surprising iaprovement in the weathering properties can be achieved by crosslinking with the alkoxysiloxanes used according to the invention. The state of the art did not give any suggestions in this direction. Rather, a person stilLed in the art had to expect, analogously to mixtures of vinylidene fluoride with acryl- ates, that the properties of the coating agents would be determined essentially by the fLuorine-containing component.

Claims (22)

1. A curable coating agent which comprises 20 to 100 % by weight of a mixture of a) a copolymer containing 40 to 60 mol % of a fluoro olefin, 5 to 45 mol % of cyclohexyl vinyl ethers, 5 to 45 mol % of alkyl vinyl ethers and 3 to 15 mol % of hydroxyalkyl vinyl ethers and b)- a hydroxysiloxane or alkoxysiloxane of the general formula
wherein R1 is a straight or branched-chain alkyl group having 1 to 4 carbon atoms, or a phenyl group; R2 is hydrogen or a straight or branched-chain alkyl group, having 1 to 4 carbon atoms; a is 1.0 to 2.2, b is 0.01 to 2.0 and a + b < 3; and the ratio of OR2 groups in the siloxane to hydroxy groups in the copolymer is 0.8 to 1.5; or c) partial reaction products thereof, which are still soluble in organic solvents.
2. A curable coating agent according to claim 1 wherein R1 is a methyl group.
3. A curable coating agent according to claim 1 or 2 wherein R2 is a C1-C4 alkyl group.
4. A curable coating agent according to any one of t'ne preceding claims wherein R2 is an ethyl group.
5. A curable coating agent according to any one of the preceding claims wherein the ratio of OR2 groups in the siloxaneto hydroxy groups in the copolymer is 1 to 1.2.
6. A curable coating agent according to any one of the preceding claims wherein a is 1.0 to 1.6.
7. A curable coating agent according to any one of the preceding claims wherein b is 0.1 to 1.5.
8. A curable coating agent according to any one of the preceding claims wherein the fluorolefin of the copolymer is tetrafluoroethylene, hexafluoropropylene, or chlorotrifluoroethylene.
9. A curable coating agent according to any one of the preceding claims wherein the alkyl vinyl ethers and hydroxyalkyl vinyl ethers of the copolymer comprise alkyl groups of 2 to 8 carbon atoms.
10. A curable coating agent according to claim 9 wherein the hydroxyalkyl vinyl ether is hydroxybutyl vinyl ether.
11. A curable coating agent according to any one of the preceding claims wherein the siloxane has the formula
12. A curable coating agent according to any one of claims 1 to 10 wherein the siloxane has the formula
13. A curable coating agent according to any one of claims 1 to 10 wherein the siloxane has the formula
14. A curable coating agent according to any one of the preceding claims which includes up to 70% by weight of solvent.
15. A curable coating agent according to claim 14 wherein the solvent comprises ketones, esters or aromatic hydrocarbons.
16. A curable coating agent according to any one of the preceding claims which includes up to 70% of pigments and/or fillers.
17. A curable coating agent according to claim 16 wherein the pigments are titanium dioxide, nickel titanium yellow, chromium titanium yellow, phthalocyanine blue or chromium oxide green.
18. A curable coating agent according to claim 16 wherein the fillers are barium sulphate, aluminium silicate, calcium sulphate or silica.
19. A curable coating agent according to any one of the preceding claims which comprises up to 2% by weight of a catalyst.
20. A curable coating agent according to claim 18 wherein the catalyst is butyl titanate, isopropyl titanate, dibutyl-tin dilaurate or p-toluene sulphonic acid.
21. A curable coating agent according to claim 1, specifically as hereinbefore mentioned.
22. A curable coating agent according to claim 1 substantially as hereinbefore described with reference to any one of the Examples.
GB8804882A 1987-03-05 1988-03-01 Curable coating agent Expired - Lifetime GB2203155B (en)

Applications Claiming Priority (1)

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DE19873707064 DE3707064C1 (en) 1987-03-05 1987-03-05 Curable coating agent

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GB2203155A true GB2203155A (en) 1988-10-12
GB2203155B GB2203155B (en) 1990-10-24

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5412015A (en) * 1992-10-01 1995-05-02 Wacker-Chemie Gmbh Sealing compositions containing polymers of ethylenically unsaturated monomers
WO2004053006A1 (en) * 2002-12-09 2004-06-24 Omnova Solutions Inc. Stain resistant coatings for flexible substrates, substrates coated therewith and related method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2036502A1 (en) * 1990-03-15 1991-09-16 Ellen O. Aeling Polyvinylether composition

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3429846A (en) * 1965-06-15 1969-02-25 Du Pont Polysilicic acid/tetrafluoroethylene secondary alcohol copolymer compositions
JPS6021686B2 (en) * 1980-08-08 1985-05-29 旭硝子株式会社 Fluorine-containing copolymer that can be cured at room temperature
JPS594473A (en) * 1982-06-28 1984-01-11 Asahi Glass Co Ltd Paint finishing method for cement base materials
JPS59152914A (en) * 1983-02-18 1984-08-31 Asahi Glass Co Ltd Curable resin composition

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5412015A (en) * 1992-10-01 1995-05-02 Wacker-Chemie Gmbh Sealing compositions containing polymers of ethylenically unsaturated monomers
WO2004053006A1 (en) * 2002-12-09 2004-06-24 Omnova Solutions Inc. Stain resistant coatings for flexible substrates, substrates coated therewith and related method

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Publication number Publication date
GB2203155B (en) 1990-10-24
GB8804882D0 (en) 1988-03-30
DE3707064C1 (en) 1988-03-10

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 19980301