Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING 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
  • C09D4/00—Coating compositions, e.g. paints, varnishes or lacquers, based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; Coating compositions, based on monomers of macromolecular compounds of groups C09D183/00 - C09D183/16

Definitions

• the present invention relates generally to coating compositions based upon (A) compounds containing activated unsaturated groups and (B) compounds containing activated CH groups.
• compositions are, in general, known from a number of references including US2759913, DE-PS-835809, US4871822 (EP-A-0160824) , US4602061, US4408018, US4217396 (GB-A-2048913) and EP-A-0448154, all of which are incorporated by reference herein for all purposes.
• US2759913 and US4871822 generally disclose a composition of the above type which may be cured at ambient and elevated temperatures. More specifically, these references generally describe, as component (A), compounds containing at least two activated ethylenic double bonds and, as component (B), a wide variety of compounds including those containing at least two activated methylene and/or monosubstituted methylene groups.
• US4602061 discloses a similar composition except that, as component (B), are specifically mentioned malonic group-containing oligomeric and polymeric esters.
• thermosetting applications One alternative for overcoming this problem in thermosetting applications is described in aforementioned EP-A-0448154, in which the basic catalyst is blocked with a particular carboxylic acid which is volatile and/or undergoes decarboxylation under curing conditions. While providing good results for elevated cure conditions, this system is not generally applicable at ambient temperatures. It is, therefore, difficult to utilize these systems for heat sensitive substrates such as wood and thermoplastic polymers, as well as in industrial and non-industrial applications like decorative coatings and refinish paints.
• the present invention provides such an alternative by utilizing a system which is curable under the influence of UV light.
• the present invention relates to a coating composition
• a coating composition comprising (A) an activated unsaturated group-containing compound, (B) an activated CH group-containing compound and (C) a basic catalyst, characterized in that the basic catalyst (C) is blocked with an acidic compound whereby the so-blocked catalyst becomes unblocked under the influence of UV light having a wavelength in the range from 250-500 nm.
• UV-deblockable basic catalysts are in general known from US4301186, US4369206, DE-A-2940333 and DE-A-2940332, all of which are incorporated by reference herein for all purposes as if fully set forth. The suitability of such blocked catalysts for use in Michael addition curing coating systems, however, is not evident from any of the above-mentioned disclosures.
• the coating compositions in accordance with the present invention are in general suitable for a variety of coatings uses, for example, as paint, impregnating, sealing and bonding compositions. They are especially suited for use as semi-one pack decorative coatings and as clearcoats in basecoat/clearcoat systems for refinish applications (e.g., for automotive refinishes).
• coating compositions possess extended potlife, good curing speed upon exposure to UV light (wavelength of 250-500 nm), and a good balance of physical and mechanical properties making them especially well suited for the aforementioned uses.
• the coating compositions in accordance with the present invention are based upon (A) activated unsaturated group-containing compounds, (B) activated CH group-containing compounds and (C) a basic catalyst, which basic catalyst is blocked in a manner more fully described below.
• suitable compounds containing activated unsaturated groups may generally be mentioned ethylenically unsaturated compounds in which the carbon-carbon double bond is activated by a carbonyl group in the ⁇ -position.
• ethylenically unsaturated compounds in which the carbon-carbon double bond is activated by a carbonyl group in the ⁇ -position.
• those compounds disclosed in previously incorporated US2759913 see especially column 6, line 35 through column 7, line 45
• DE-PS-835809 see especially column 3, lines 16-41
• US4871822 see especially column 2, line 14 through column 4, line 14
• US4602061 see
• ( eth)acrylic esters of compounds containing 1-6 hydroxyl groups and 1-20 carbon atoms.
• (meth)acrylic acid may be used, for example, crotonic acid and cinnamic acid. These esters may optionally contain hydroxyl groups.
• Especially preferred examples include hexane
• diol diacrylate trimethylol propane triacrylate and pentaerythritol triacrylate.
• polyester and/or alkyd resins containing pendant activated unsaturated groups include, for example, urethane (meth)acrylates obtained by reaction of a polyisocyanate with an hydroxyl group-containing (meth)acrylic ester, e.g., an hydroxyalkyl ester of (meth)acrylic acid or a compound prepared by esterification of a polyhydroxyl compound with less than a stoichiometric amount of (meth)acrylic acid; polyether (meth)acrylates obtained by esterification of an hydroxyl group-containing polyether with ( eth)acrylic acid; polyfunctional (meth)acrylates obtained by reaction of an hydroxyalkyl (meth)acrylate with a polycarboxylic acid and/or a polyamino resin; poly(meth)acrylates obtained by reaction of (meth)acrylic acid with an epoxy resin; and polyalkylmaleates obtained by reaction of a monoalkyl aleate
• activated unsaturated group-containing compounds are the aforementioned poly(meth)acrylates obtained by the reaction of (meth)acrylic acid with an epoxy resin.
• the acid value of the activated unsaturated group-containing compounds be about 2 or less.
• suitable compounds containing activated CH groups may be mentioned a wide variety of compounds as generally disclosed in previously incorporated US4871822 (see especially column 4, lines 15-28), which compounds contain a methylene and/or onosubstituted methylene group in the ⁇ -position to two activating groups such as, for example, carbonyl , cyano, sulfoxide and/or nitro groups.
• Preferred of these are compounds containing a methylene group in the ⁇ -position to two carbonyl groups, such as malonate and/or acetoacetate group-containing compounds.
• malonate group-containing compounds may be mentioned alonic acid esters as disclosed in previously incorporated US2759913 (see especially column 8, lines 51-52), and malonate group-containing oligomeric and polymeric compounds as disclosed in previously incorporated US4602061 (see especially column 1, line 10 through column 2, line 13).
• alonic acid esters as disclosed in previously incorporated US2759913 (see especially column 8, lines 51-52)
• malonate group-containing oligomeric and polymeric compounds as disclosed in previously incorporated US4602061 (see especially column 1, line 10 through column 2, line 13).
• Preferred of these are the oligomeric and/or polymeric malonate group-containing compounds such as, for example, polyurethanes, polyesters, polyacrylates, epoxy resins, polyamides and polyvinyl resins containing malonate groups in the main chain, pendant or both.
• the malonate group-containing polyurethanes may be obtained, for example, by reacting a polyisocyanate with an hydroxyl group- containing ester of a polyol and malonic acid, or by esterification or transesterification of an hydroxy functional polyurethane with malonic acid or a dialkylmalonate.
• the malonate group-containing polyesters may be obtained, for example, by the polycondensation of malonic acid, an alkyl malonic acid (such as ethyl malonic acid), a mono- or dialkyl ester of such a malonic acid, and/or the reaction product of a malonic ester and an alkyl (meth)acrylate, optionally with other di- or polycarboxylic acids; with di- and/or higher functional hydroxy compounds; and, optionally onofunctional hydroxy and/or carboxyl compounds.
• an alkyl malonic acid such as ethyl malonic acid
• a mono- or dialkyl ester of such a malonic acid and/or the reaction product of a malonic ester and an alkyl (meth)acrylate
• alkyl (meth)acrylate optionally with other di- or polycarboxylic acids
• di- and/or higher functional hydroxy compounds optionally onofunctional hydroxy and/or carboxyl compounds.
• the malonate group-containing epoxy esters may be obtained, for example, by esterifying an epoxy resin with malonic acid or a malonic monoester, or by transesterification with a dialkyl malonate, optionally with other carboxylic acids and derivatives thereof.
• the malonate group-containing polyamides may be obtained, for example, in the same manner as the polyesters, wherein at least a part of the hydroxy compound is replaced with a mono- and/or polyvalent primary and/or secondary a ine.
• Other malonate group-containing polymers may be obtained by the transesterification of an excess of a dialkyl malonate with an hydroxy-functional polymer such as, for example, a vinyl alcohol/styrene copolymer. In this manner, a polymer with malonate group-containing side-chains may be formed. Any excess dialkyl malonate may be removed under reduced pressure or, optionally, be used as a reactive solvent.
• malonate group-containing compounds in which the malonic acid structural unit is cyclized, for example, by formaldehyde, acetaldehyde, acetone or cyclohexanone.
• malonate group-containing compounds for use with the present invention are the malonate group-containing oligomeric esters, polyesters, polyurethanes and epoxy esters containing 2-100, more preferably 2-20, malonate groups per molecule. It is also especially preferred that such malonate group-containing compounds have a number average molecular weight (Mn) in the range of from about 250 to about 3000, and an acid number of about 2 or less.
• Mn number average molecular weight
• acetoacetate group-containing compounds may be mentioned acetoacetic esters as disclosed in previously incorporated US2759913 (see especially column 8, lines 53-54), diacetoacetate compounds as disclosed in previously incorporated US4217396 (see especially column 2, line 65 through column 3, line 27), and acetoacetate group-containing oligomeric and polymeric compounds as disclosed in previously incorporated US4408018 (see especially column 1, line 51 through column 2, line 6). Preferred of these are the oligomeric and/or polymeric acetoacetate group-containing compounds.
• Suitabl e acetoacetate group-containing ol igomeri c and polymeri c compounds can be obtained, for example, from polyal cohol s and/or hydroxy-functi onal polyether, polyester, polyacryl ate, vi nyl and epoxy oligomers and polymers by reaction with diketene or transesterification with an alkyl acetoacetate.
• Such compounds may also be obtained by copolymerization of an acetoacetate functional acrylic monomer with other vinyl- and/or acrylic-functional monomers.
• acetoacetate group-containing compounds for use with the present invention are the acetoacetate group-containing oligomers and polymers containing at least 2 acetoacetate groups. It is also especially preferred that such acetoacetate group-containing compounds should have an Mn in the range of from about 234 to about 30000, and an acid number of about 2 or less.
• the activated CH groups-containing compounds may be utilized in ena ine form such as disclosed in EP-A-0420133, which is incorporated by reference herein for all purposes as if fully set forth.
• component (A) and (B) react with each other through a Michael addition, in which the activated CH group of component (B) adds to one of the carbon atoms of the activated unsaturated group of component (A).
• Components (A) and (B) are preferably contained in the coating compositions in an amount such that the ratio of the number of activated CH groups to the number of activated unsaturated groups is in the range of about 0,25 to about 4,0, more preferably in the range of about 0,5 to about 2,0.
• the blocked basic catalysts suitable for use with the present coating compositions are blocked with an acidic compound, whereby the so-blocked catalyst becomes unblocked under the influence of UV light having a wavelength in the range from 250-500 nm.
• amine catalysts may be mentioned those of the amidine type, for example, tetramethyl guanidine, 1,4-dihydropyrimidines, l,8-diaza-bicyclo[5.4.0]undec-7-ene, l,4-diaza-bicyclo[2.2.2]octane and 2-alkyl-N-al yl imidazolines.
• ammonium catalysts may be mentioned quaternary ammonium compounds, for example, quaternary ammonium hydroxides such as tetrabutyl ammonium hydroxide; quaternary ammonium alkoxides such as benzyltrimethyl ammonium methoxide and dilauryldimethyl ammonium methoxide; and quaternary ammonium carbanions such as benzyltrimethyl ammonium acetyl acetate.
• quaternary ammonium hydroxides such as tetrabutyl ammonium hydroxide
• quaternary ammonium alkoxides such as benzyltrimethyl ammonium methoxide and dilauryldimethyl ammonium methoxide
• quaternary ammonium carbanions such as benzyltrimethyl ammonium acetyl acetate.
• phosphane compounds may be mentioned those disclosed in previously incorporated US4871822 (column 7, line 48 through column 8, line 2), and particularly the tertiary phosphanes disclosed therein.
• phosphane compounds may be mentioned tris(hydroxymethyl)phosphane, triphenylphosphane and tris(p-tolyl)phosphane.
• These basic catalysts (unblocked) are generally utilized in amounts ranging from about 0,05 wt% to about 3,0 wt%, preferably from about 0,1 wt% to about 1,0 wt%, based upon the combined weight of components (A) and (B) .
• Suitable blocking agents for these basic catalysts comprise acidic compounds selected from:
• suitable ⁇ -keto carboxylic acid blocking agents are known from previously incorporated US4301186 (column 1 line 35 through column 2, line 58) and US4369206 (column 1, line 36 through column 2, line 37).
• phenyl glyoxylic acid, 1-naphtyl glyoxylic acid, pyruvic acid and benzylidiene pyruvic acid are known from previously incorporated US4301186 (column 1 line 35 through column 2, line 58) and US4369206 (column 1, line 36 through column 2, line 37).
• phenyl glyoxylic acid 1-naphtyl glyoxylic acid
• pyruvic acid pyruvic acid
• benzylidiene pyruvic acid benzylidiene pyruvic acid.
• Suitable aromatic or N-heterocyclic substituted formic, acetic and oxyacetic acid blocking agents are known from previously incorporated DE-A-2940333 (page 7, line 15 through page 8, line 15).
• phenyl acetic acid, 1-naphtyl acetic acid and 9-anthracene carboxylic acid are known from previously incorporated DE-A-2940333 (page 7, line 15 through page 8, line 15).
• phenyl acetic acid 1-naphtyl acetic acid and 9-anthracene carboxylic acid.
• Suitable halide blocking agents are generally known from DE-A-2940332. Preferred are the anions chloride, bromide and iodide. The halide blocking agents, however, are in general less preferred because a low molecular weight halogenide may be released upon unblocking of the catalyst.
• the acidic compound is preferably utilized in an amount of from about 10 to about 125, more preferably from about .25 to about 125, and especially from about 50 to about 100, equivalent percent required to neutralize the basic catalyst. Within these ratios, the potlife of the composition can be readily varied, for example, between h hour at 20°C to more than 6 weeks at 50°C.
• the basic catalyst and blocking agent can be mixed in situ and added to the composition in quantities to result in the desired ratio as set forth above.
• a salt of the catalyst and blocking agent can be pre-prepared and added to the composition.
• the curing of the above-described coating compositions is preferably carried out at ambient temperatures (e.g., 10-30°C) under the influence of UV light of a wavelength 250-500 nm, which can be from a UV source or even daylight.
• the coating compositions in accordance with the present invention may optionally contain one or more pigments, dyes and usual intermediary agents, additives and/or solvents.
• suitable inert organic solvents include esters, ketones aromatic and aliphatic hydrocarbons.
• suitable reactive organic solvents include dimethyl malonate, diethyl malonate, ethyl acetoacetate and 2-ethylhexyl acrylate.
• preferred additives may be mentioned minor amounts of a co-binder not containing activated unsaturated or CH groups, for example, cellulose acetate butyrate, acrylic, epoxy and polyester resins.
• these co-binders are commonly utilized in the coatings industry to modify certain properties such as drying speed and adhesion to substrates.
• a UV sensitizer such as anthracene, which is used to increase the amount of UV light absorbed by the coating composition.
• the coating compositions in accordance with the present invention are suitable for a variety of coatings uses, for example, as paint, impregnating, sealing and bonding compositions.
• a preferred application is as a semi one-pack decorative coating.
• a clearcoat in a basecoat/clearcoat system for refinish applications e.g., automobile refinish.
• Suitable basecoats for use in such systems are in general well-known in the art.
• coating compositions may be applied to a substrate in any convenient manner such as, for example, by brushing, spraying or dipping.
• Suitable substrates include metals, wood, board, plastics and leather.
• reaction mixture was cooled to 140°C and an additional peroxide solution of 50,0 pbw of Solvesso 100 and 10,0 pbw of Trigonox 42S was added.
• the recovered salt was purified by means of recrystallization from a solution in 40 ml tetrahydrofuran, yielding a pale yellow salt in a yield of about 67%.
• a coating composition was prepared from 30,0 grams of (Al), 16,5 grams of (Bl), 3,4 grams of butylacetate and 9,8 grams of a 10% solution of (Cl) in a mixture of butylacetate/methanol (87,5/12,5).
• compositions were tested for geltime by storing 100 grams of the reaction mixture in a closed tin at a temperature as set forth below. The geltime is reported as the time when the mixture no longer flowed as a liquid upon stirring with a spatula.
• compositions were applied onto a tin plated steel panel with a drawbar to a dry layer thickness of ca. 50 ⁇ m.
• the panel of Example 1 was irradiated with a 400 Watt mercury lamp at a distance of 38 cm.
• the panel of Comparative Example 1 was not irradiated.
• the petrol resistance of the so-applied coatings was tested qualitatively. After one week cure at 23°C a drop of petrol was applied to the test panel. After five minutes, the panel was inspected for coating softening.
• the pendulum hardness of the so-applied coatings was also tested after one day and one week cure at 23°C with the aid of a Persoz apparatus.
• Example 1 >1 week at 50°C O.K. 35" 137" 51 ⁇ m
• Example 1 was repeated except that 25 grams of (A2), 33 grams of (Bl) and 13,4 grams of the 10% solution of (Cl) were utilized.
• Example 2 >10 days at 50°C good 123" 249" 45 ⁇ m
• Example 1 The composition of Example 1 was repeated except that the solution of (Cl) was replaced with 12,1 grams of a 10% solution of (C2) in a mixture of butylacetate/methanol (87,5/12,5).
• This composition and the composition of Comparative Example 1 were applied onto a tin plated steel panel with a drawbar to a dry film thickness of ca. 80 ⁇ m. For each composition two panels were prepared. One of each was exposed to daylight, while the other was stored in darkness. The petrol resistance and pendulum hardness were measured as above.

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

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Cited By (17)

Citations (4)

• 1994
  • 1994-05-03 CA CA002163875A patent/CA2163875A1/en not_active Abandoned
  • 1994-05-03 CN CN 94192602 patent/CN1126484A/zh active Pending
  • 1994-05-03 WO PCT/EP1994/001451 patent/WO1994028075A1/en not_active Application Discontinuation
  • 1994-05-03 EP EP94916207A patent/EP0702707A1/en not_active Withdrawn
• 1995
  • 1995-11-22 FI FI955613A patent/FI955613A/fi not_active Application Discontinuation
  • 1995-11-24 NO NO954787A patent/NO954787L/no unknown

Patent Citations (7)

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