WO1997006218A1 - Composition de peinture en poudre - Google Patents

Composition de peinture en poudre Download PDF

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Publication number
WO1997006218A1
WO1997006218A1 PCT/NL1996/000294 NL9600294W WO9706218A1 WO 1997006218 A1 WO1997006218 A1 WO 1997006218A1 NL 9600294 W NL9600294 W NL 9600294W WO 9706218 A1 WO9706218 A1 WO 9706218A1
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WO
WIPO (PCT)
Prior art keywords
crosslinker
aliphatic
group
acid
epoxy
Prior art date
Application number
PCT/NL1996/000294
Other languages
English (en)
Inventor
Pieter Gijsman
Daniel Joseph Maria Tummers
Robert Van Den Berg Jeths
Original Assignee
Dsm N.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dsm N.V. filed Critical Dsm N.V.
Priority to AU65342/96A priority Critical patent/AU6534296A/en
Publication of WO1997006218A1 publication Critical patent/WO1997006218A1/fr

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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
    • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/16—Nitrogen-containing compounds
    • C08K5/17—Amines; Quaternary ammonium compounds
    • C08K5/18—Amines; Quaternary ammonium compounds with aromatically bound amino groups
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/49—Phosphorus-containing compounds
    • C08K5/51—Phosphorus bound to oxygen
    • C08K5/52—Phosphorus bound to oxygen only
    • C08K5/524—Esters of phosphorous acids, e.g. of H3PO3
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/49—Phosphorus-containing compounds
    • C08K5/51—Phosphorus bound to oxygen
    • C08K5/52—Phosphorus bound to oxygen only
    • C08K5/527—Cyclic esters
    • 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
    • C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
    • 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
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/03—Powdery paints
    • C09D5/033—Powdery paints characterised by the additives
    • C09D5/036—Stabilisers

Definitions

  • thermosetting powder paint composition comprising
  • crosslinker comprising at least a C 5 -C 26 linear or branched aliphatic chain and having an epoxy functionality greater than 1, the epoxy group being present on the aliphatic chain
  • Such a composition is known from EP-A-600546. Although good coating properties can be obtained with the compositions as described, further optimization is desirable as regards the resistance to discolouration upon (prolonged) exposure to a high temperature in electrical or gas furnaces.
  • stabilizer (iv) is a phosphite that comprises at least a group of formula (1):
  • R 1 is an aliphatic group
  • R 2 is an aliphatic or aromatic group
  • R 3 is an aromatic group and where each aliphatic and aromatic group may be substituted.
  • the powder paint composition according to the present invention comprises a polymer and crosslinker (together forming the binder) as disclosed in EP-A-600546, the disclosure of which is herein incorporated by reference.
  • the polymer preferably has a Tg (glass transition temperature) higher than 40°C, in particular higher than 60°C.
  • the viscosity of the polymer is preferably lower than 8000 dPas at 158°C and will usually be higher than 100 dPas (measured according to Emila).
  • the molecular weight of the polymer is
  • the polymer is preferably a polyester, polyacrylate or polyether, with carboxy, hydroxy, anhydride or epoxy as reactive groups.
  • the polymer preferably has a functionality lower than 1.25 meq/g of polymer, more in particular lower than 0.9 meq/g. The functionality is preferably higher than 0.18 meq/g. Suitable polymers are described in EP-A-600546.
  • the crosslinker comprises linear or branched aliphatic chains with 5-26 carbon atoms, on which epoxy groups are present.
  • the amount of oxirane oxygen present on the aliphatic chains as epoxy group is more than 0.1 meq/g relative to the binder composition.
  • the amount of oxirane oxygen on the aliphatic chains will usually be less than 1.3 meq/g, and is preferably less than 1.0 meq/g.
  • the crosslinker preferably comprises linear or branched chains with more than 12 carbon atoms.
  • the aliphatic chains on which the epoxy groups are present are linear.
  • crosslinker is preferably more than 2 wt.%, in
  • the amount is usually less than 20 wt.%, and in practice it is often less than 15 wt.%.
  • the epoxy group is not a terminal group.
  • the epoxy group is not present on the ⁇ , ⁇ -position relative to a heteroatom, and not present on the ⁇ , ⁇ position relative to a carbon, if a heteroatom is bound to that carbon atom by a double bond.
  • the crosslinker substantially contains epoxy groups of a structure according to formula (2)
  • the crosslinker comprises several aliphatic chains with one or more epoxy groups.
  • the functionality of the crosslinker is preferably greater than 1.2, and in particular greater than 2.1. If the aliphatic chains form part of a polymeric crosslinker, the functionality is usually lower than 50.
  • crosslinker use can be made, for instance, of epoxidized fatty acid esters, epoxidized etherized fatty alcohols or epoxidized amidated fatty amines.
  • epoxidized fatty acid esters such as, for instance, epoxidized oils.
  • epoxidized linseed oil or soybean oil are particularly suitable.
  • crosslinkers described hereinabove can also be used in combination with other crosslinkers.
  • Crosslinkers containing epoxy groups such as, for example, triglycidyl isocyanurate (TGIC),
  • polybisphenol-A-epoxides such as, for example, the various Epikote ® types can be used in combination with crosslinkers described herein above.
  • Another class of crosslinkers that can be used in such combinations are compounds containing (blocked) isocyanate groups, such as, for example, the caprolactam blocked isophorone diisocyanate trimer.
  • a still further class of crosslinkers such as, for example, the caprolactam blocked isophorone diisocyanate trimer.
  • combinable crosslinkers contain ⁇ -hydroxyalkyl amide groups, such as, for example, Primid XL 522 ® (Rohm and Haas).
  • Polyfunctional oxazolines can also be used in combination with the epoxy-functional crosslinkers based on at least one aliphatic chain having the epoxy functionality.
  • the amount of the epoxy-functional crosslinker comprised of at least one aliphatic chain carrying epoxy functionality is preferably such that more than 20% of crosslinking is obtained through that crosslinker. More preferably, it is desired that more than 35% of crosslinking, and in particular more than 50% of crosslinking, be obtained using the theretofore described crosslinking comprising aliphatic chains.
  • crosslinker described above can be used in combination with other crosslinkers, it is preferred to use the crosslinker comprising aliphatic chains as the main crosslinker, and more preferably as the substantial sole crosslinker.
  • the binder composition comprises more than 50 wt.% polymer and less than 50 wt.% crosslinker.
  • the binder composition contains 98-70 wt.% polymer and 2-30 wt.% crosslinker.
  • the binder is prepared as described in WO-A-94/26808, the disclosure of which is incorporated herein by reference.
  • the catalyst catalyzes the reaction between the polymer (i) and the crosslinker (ii).
  • Suitable catalysts are described, for instance, in EP-A-600546.
  • a nitrogen or metal containing compound is preferably used as catalyst.
  • epoxy- anhydride reactions use is preferably also made of one of the nitrogen or metal containing compounds as described here.
  • an additional crosslinker such as for instance a polyanhydride, dicyanodiamide
  • polycarboxylic acid or a polyphenol.
  • catalyst a nitrogen or metal containing compound is preferably used.
  • Dicyanodiamides can also be used as catalyst.
  • Suitable nitrogen containing compounds include, for instance, compounds derived from
  • guanidines and imidazoles such as for instance tetramethyl guanidine (TMG), acetyl-TMG, isocyanate-TMG adducts, 1-benzimidazole, 2-methylimidazole, 5.6-dimethyl-benzimidazole and 1-ethylimidazole are very suitable for these contribute to good colour stability.
  • TMG tetramethyl guanidine
  • acetyl-TMG isocyanate-TMG adducts
  • 1-benzimidazole 2-methylimidazole
  • 2-methylimidazole 5.6-dimethyl-benzimidazole
  • 1-ethylimidazole 1-ethylimidazole
  • Suitable metal containing compounds particularly suitable for acid-epoxy, hydroxy-epoxy- anhydride, epoxy-anhydride and epoxy-epoxy-anhydride reactions, include for instance a metal hydroxide, metal alkanolate or metal carboxylate.
  • the metal can be selected from lithium, sodium, potassium, cesium, magnesium, calcium, tin, copper or zinc.
  • the preferred metal is lithium or sodium, because they have a very good catalytic activity.
  • Lithium is particularly preferred.
  • the metal compound is a metal alkanolate or metal carboxylate.
  • this compound has more than 3, and in particular more than 6, carbon atoms.
  • the carboxylic acid (of the metal carboxylate) has a pKa between 3 and 8.
  • carboxylic acids examples include saturated aliphatic mono- and dicarboxylic acids, unsaturated aliphatic acids, carbocyclic carboxylic acids, heterocyclic carboxylic acids, hydroxycarboxylic acids, alkoxycarboxylic acids, oxocarboxylic acids, aminocarboxylic acids and amidecarboxylic acids.
  • monocarboxylic acids are formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, pivalic acid, lauric acid, myristic acid, palmitic acid, octanoic acid, 2-ethyl hexanoic acid, stearic acid, hydroxypivalic acid and/or isononanoic acid.
  • Suitable aliphatic monocarboxylic acids are acids that can be obtained by the Koch reaction such as, for instance, 2,2-dimethylpropanoic acid
  • neododecanoic acid (Versatic 10 ® ).
  • saturated aliphatic dicarboxylic acids are oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, decanedicarboxylic acid, azelaic acid and sebacic acid.
  • unsaturated aliphatic acids are acrylic acid, propiolic acid, methacrylic acid, crotonic acid (trans-isomer), isocrotonic acid (cis- isomer), oleic acid (cis-isomer), linoleic acid, linolenic acid, elaidic acid (trans-isomer), maleic acid, fumaric acid, citraconic acid and mesaconic acid.
  • carbocyclic carboxylic acids examples include camphoric acid, benzoic acid, phthalic acid,
  • heterocyclic carboxylic acids examples include furoic acid (furan carboxylic acid), nicotinic acid and isonicotinic acid.
  • oxocarboxylic acids are glycolic acid, lactic acid, glyceric acid, malic acid, tartaric acid, tropic acid, benzilic acid, salicylic acid, anisic acid, vanillic acid, veratric acid, piperonylic acid, gallic acid, 6-oxohexanoic acid, 5-oxovaleric acid, 3-oxovaleric acid, 3,5-dioxovaleric acid, 2-oxo-1-cyclohexanecarboxylic acid, ⁇ -oxocyclohexane propionic acid, ⁇ -oxo-6-chrysene butyric acid and ⁇ -oxo-3-pyridine propionic acid.
  • decanoic acid octanoic acid, 2-ethyl hexanoic acid, stearic acid, lauric acid, neodecanoic acid, an acid obtained by the Koch
  • decane dicarboxylic acid and/or benzoic acid are employed. If desired, use can also be made of a mixture of 2 or more of the above-mentioned compounds.
  • Suitable alcohols are, for instance, monohydric alcohols, diols and triols such as, for instance, methanol, ethanol, propanol, isopropanol, butanol and isomers thereof, glycol, neopentylglycol, butanediol, hexanediol, cyclohexane dimethylol, glycerol, trimethylol propane and tris(hydroxyethyl) isocyanurate.
  • monohydric alcohols such as, for instance, methanol, ethanol, propanol, isopropanol, butanol and isomers thereof, glycol, neopentylglycol, butanediol, hexanediol, cyclohexane dimethylol, glycerol, trimethylol propane and tris(hydroxyethyl) isocyanurate.
  • the appropriate quantity of catalyst for the reaction is preferably chosen so as to obtain the desired degree of curing and flow.
  • curing takes place for instance in 20 to 30 minutes at 150°C, or in 10 to 15 minutes at 180°C, through to 5 to 10 minutes at 200°C.
  • the quantity of catalyst is usually chosen between 0.1 and 5 wt.% and is preferably between 0.4 and 3 wt.% relative to the binder.
  • At least one of the stabilizers is a phosphite comprising at least one group according to formula (1):
  • R 1 is an aliphatic group
  • R 2 is an aliphatic or aromatic group
  • R 3 is an aromatic group, and where the aliphatic and aromatic groups may be substituted.
  • the molecular weight is generally lower than 1500, preferably lower than 1000. If the phosphite is an oligo- or polyphosphite, the molecular weight is generally lower than 20,000.
  • the melting point of the phosphite is
  • the phosphite is a di- or triphosphite, because these compounds prove to be very effective.
  • the phosphite always has three groups on a phosphorus atom that are bound via an oxygen atom.
  • the three groups are either aliphatic or aromatic, at least one being aliphatic and at least one being aromatic.
  • the aliphatic and the aromatic groups may be substituted with aromatic and aliphatic groups.
  • heteroatoms such as for instance oxygen, nitrogen, sulphur, phosphorus or halogens may be present.
  • bridging groups such as for instance groups based on 1,3-propanediol or groups based on 2,2'-bisphenol.
  • the aliphatic and the aromatic groups may also form bridging groups for several phosphites, such as for instance groups based on pentaerythritol and bisphenol-A.
  • the aromatic groups are preferably phenyl groups.
  • the phenyl groups may be substituted with one or more alkyl, aryl, halogen, alkoxy or alkylamide groups.
  • the phenyl groups are substituted with at least one or more linear or branched alkyl groups with 3-24 carbon atoms and/or with aryl groups, whether or not substituted, containing 6-36 carbon atoms.
  • at least one of the substituents is at the ortho position.
  • Examples of highly suitable substituents are t-butyl, isopropyl, n-nonyl, isononyl, stearyl, phenyl, benzyl and isopropyl phenyl.
  • the aliphatic groups are preferably linear or branched hydrocarbons, optionally with ether or amine groups.
  • the aliphatic groups may contain aromatic or heterocyclic groups. Examples of suitable aliphatic groups are tris-hydroxyethyl-isocyanurate, tris- hydroxyethylamine, pentaerythritol, 2,2-cyclohexyl-1,3-propanediol, ethanol, dodecanol and 2-ethylhexanol.
  • a highly suitable class of compounds are phosphites in which every phosphorus atom in the polyphosphite is surrounded by a 2,2-spiro-substituted 1,3-propanediol compound and a substituted phenol compound.
  • the 2,2-spiro-substituted 1,3-propanediol compound may be 2,2-dialkyl-1,3-propanediol, but it may also form part of a group comprising several 2,2-spiro- substituted 1,3-propanediol compounds.
  • the substituted phenol compound may be a mono- or polyhydroxy compound, and may for instance comprise 1-5 aryl groups.
  • Suitable stabilizers include compounds according to formulas (3), (4), (5) and (6):
  • R 4 represents H or one or more substituents on the aromatic ring ⁇ ; where R 4 has the above-mentioned meaning and where R 5 together form an ether, (alkyl)amine or hydrocarbon bridge, or independently represent hydrogen, hydroxy, alkoxy or alkyl with 1-6 carbon atoms;
  • R 4 has the meaning defined above, and n is an integer between 2 and 40;
  • R 4 has the meaning defined above, R 6 each
  • Y represents a bridge between the two phenyl groups or a sulphur, amine, i-propylamine, methyl, 2,2'-propyl or
  • the stabilizer is a bisphenyl pentaerythritol-di-phosphite according to formula (3).
  • Highly suitable compounds with 2 alkyl groups and one aryl group per phosphite are for instance bis-[2,4-di-tertiary butyl-phenyl]-pentaerythritol-di-phosphite (Ultranox 626®), bis-[2,6-di-tertiary butyl-4-methylphenyl]-pentaerythritol-di-phosphite (MARK PEP 36 ® ), bis (2,4-dicumylphenyl)pentaerythritol diphosphite (Doverphos ® S-9228) and bis- [nonylphenyl]pentaerythritol diphosphite (MARK PEP 4C ® ).
  • Highly suitable compounds with 2 aryl groups and one aliphatic group per phosphite are tris[2,2'-bis(6-tert.butyl(phenyl)ethylphosphite]amine (Irgafos ® 12 from Ciba Geigy), 2,2-methylene-bis-(4,6-di-t-butylphenyl)-octyl phosphite (MARK HP 10 ® ) and bis (2,4-ditert.butyl-6-methylphenyl)ethylphosphite.
  • the stabilizers according to the invention prove to be effective in suppressing discolouration, whereas other stabilizers having a somewhat comparable structure give much less or hardly any improvement in the resistance to discolouration upon exposure to high temperatures. Examples of
  • compounds that are not very effective are compounds with three aliphatic groups on the phosphite (such as for instance distearyl-pentaerythritol-diphosphite); or a compound with only aromatic groups, such as for instance tris-[2,4-ditertiary butylphenyl ]phosphite, tris-nonylphenyl phosphite or tetrakis-[2,4-ditertiarybutyl-phenyl]-4,4'-biphenylene-diphosphonite.
  • three aliphatic groups on the phosphite such as for instance distearyl-pentaerythritol-diphosphite
  • a compound with only aromatic groups such as for instance tris-[2,4-ditertiary butylphenyl ]phosphite, tris-nonylphenyl phosphite or tetrakis-[2,4-diter
  • the stabilizer according to the invention belongs to the class of compounds that is also called secondary antioxidants.
  • composition according to the invention preferably also a primary antioxidant is used.
  • primary antioxidants use is preferably made of
  • sterically hindered phenols such as for instance
  • Substituted phenols such as for instance Irganox 565 ® are also very suitable.
  • This class of compounds generally has a molecular weight below 2000, and the compounds contain one or more phenol groups -substituted at at least one ortho position (relative to the phenolic hydroxy).
  • Very suitable substituents are t-butyl, i-propyl, phenyl, methylphenyl, phenol, methylcyclohexyl, methyl and ethyl.
  • the primary antioxidant contains 2 or more sterically hindered phenol groups.
  • Aromatic amines are less suitable for prevention of discolouration in gas furnaces (NO x ). Aromatic amines can be used singly or in combination with another primary antioxidant. Very suitable aromatic amines are 4,4'-di-cumyl-diphenyl amine, 2,2,4-trimethyl-1,2-dihydro-quinoline, 4,4-di-octyl-di-phenylamine or N,N'-di-sec-butyl-para ⁇ phenylene diamine.
  • the stabilizers are each used in an amount of between 0.05 and 2 wt.% (relative to the total amount of the binder). In particular use is made of between 0.25 and 1 wt.%. If an aromatic amine is used in combination with a sterically hindered phenol, the amount of aromatic amine is generally small, and an effective amount is for instance an amount between 0.05 and 1.0 wt.%, relative to the total amount of the binder. Preferably, an amount between 0.1 and 0.5 wt.% is chosen.
  • At least one or more primary antioxidants in a total amount of 0.25-1 wt .% (relative to the binder) and one or more secondary antioxidants in an amount of 0.5-1 wt.%.
  • the resistance to discolouration is preferably determined in several experiments.
  • the discolouration on prolonged heating in air circulation ovens is measured (usually relative to the normally cured coating) by exposing a test plate to the desired test conditions. Customary tests are: 1 hour at 200°C, 30 minutes at 220°C and 10 minutes at
  • the absolute b* value is indicated.
  • the (amounts of the) stabilizers are chosen so that the b* value (absolute) on heating for 1 hour at 200°C is lower than 3, with special preference lower than 2, and that the b* value on heating for 10 minutes at 240°C is lower than 5, preferably lower than 2.
  • the discolouration of the coating (b* value, absolute) at 10', No x , 215°C is preferably lower than 7, in particular lower than 5.
  • b* values can be measured in standard compositions in which, relative to the binder, use is made of 50 wt.% TiO 2 (Kronos 2160®), 1.5 wt.% Resiflow PV5®, 0.5 wt.% benzoin, a catalyst and stabilizers. In addition, measurements are performed on a reference composition consisting of Uralac P5012/TGIC in a standard formulation without addition of an extra catalyst of stabilizer.
  • Such additives are not usually needed to prevent discolouration upon 'overbake'.
  • examples of such additives are thioethers, UV-absorbing additives such as for instance benzotriazoles and
  • HALS compounds and UV-absorbing additives may be useful for obtaining an improved UV stability.
  • Optical whiteners may be useful to ensure that the colour is relatively white after curing.
  • Tinuvin 900 ® Tinuvin 900 ® .
  • additives that affect the colour (stability) are often used, such as for instance degassers (benzoin), flow-promoting agents (polyalkyl acrylates) and optionally agents promoting tribo-charging (spherically hindered amines).
  • degassers benzoin
  • flow-promoting agents polyalkyl acrylates
  • optionally agents promoting tribo-charging spherically hindered amines
  • the powder paint composition optionally contains pigments and/or fillers.
  • pigments and/or fillers examples include titanium dioxide, zinc sulphide, iron oxide and chromium oxide, while azo compounds are very suitable as organic pigments.
  • Fillers comprise for instance metal oxides, silicates, melamine, carbonates and sulphates. (These pigments and fillers do not form part of the 'binder').
  • a powder paint composition can be prepared by mixing the binder composition with the catalyst, the stabilizer and optionally pigments, other additives, and optionally extra curing agents at a temperature that is above the melting point of the binder
  • the invention also relates to a binder composition that is suitable for use according to the invention, which binder composition comprises the polymer, the crosslinker and the stabilizer according to the invention.
  • the invention is carried out in a two-component system in which the first component comprises the polymer, the crosslinker and the stabilizer, and a second component a small part of the polymer (or another polymer) and the catalyst.
  • the first component the larger part of the binder
  • the second component the second component
  • pigments and optionally other crosslinkers or additives are first mixed in powder form and subsequently mixed in an extruder at a temperature above the melting point of the composition in such a short time (less than a few minutes) that hardly any reaction has taken place between the polymer and the crosslinker.
  • homogeneous mixture is cooled, crushed and ground to obtain a powder having a particle size of less than 90 ⁇ m.
  • a very suitable method of preparing the first component is described in WO-A-94/26808, the disclosure of which is incorporated herein by reference.
  • the polymer is mixed with a crosslinker at a temperature at which the viscosity is lower than 5000 dPas, for instance in a static mixer or a rotor/stator, in such a short time that hardly any reaction takes place between the polymer and the crosslinker.
  • This mixing step is generally carried out at a temperature between 140 and 220°C, the residence time of the mixed components being shorter than 60 seconds.
  • This process is very suitable in particular if the crosslinker is a liquid or viscous substance at room temperature.
  • the phosphite is preferably mixed in advance with the crosslinker.
  • the various ingredients of the binder composition can also be mixed with the other
  • Powder paints according to the invention can be applied in the customary manner, for instance by electrostatic spraying of the powder onto an earthed substrate and curing of the coating by exposure to heat at a suitable temperature for a sufficiently long period.
  • the powder can for instance be heated in a gas furnace, an electric furnace or by means of infrared radiation.
  • thermosetting powder paint compositions intended for industrial applications are described further, in general terms, in Misev, Powder Coatings, Chemistry and Technology, pp. 141-173 (1991).
  • inventions can be applied in powder coatings for use on metal, wood and plastic substrates.
  • Examples include general-purpose industrial coatings, for instance for aluminium window frames, coatings for machinery and for instance for cans and for domestic and other small items of equipment, such as for instance air
  • a powder paint was prepared by mixing a two-component system with 300 g of TiO 2 (Kronos 2160 ® ), 9 g of flow-promoting agent (Resiflow PV5 ® ) and 3 g of degasser (benzoin) in a mixer.
  • the two-component system consisted of a first component comprising 516 g of polyester with an acid number of 29 mg KOH/gram resin, a viscosity of 820 dPas (measured according to Emila, 158°C) and a functionality of 2.1, 54 g of epoxidized linseed oil, 4.5 g of MARK PEP 36 ® (0.75 wt.% relative to the binder) and 3 g of Santowhite Powder ® (0.5 wt.% relative to the binder).
  • the first component was prepared according to the process described in WO-A-94/26808.
  • the second component consisted of 20 wt.% lithium versatate in a polyester resin as described above; 30 g of this component were used.
  • the mixture was melted and homogenized in an extruder (Prism, 16 mm) at 130 °C, after which the homogeneous mixture was cooled, crushed and ground.
  • a powder with particles smaller than 90 ⁇ m was screened out and sprayed electrostatically onto an aluminium Q panel AL46 plaque of 0.6 mm thickness.
  • the curing time was 10 minutes at 200°C and the resulting cured coating had a layer thickness of 50 ⁇ m.
  • the coating obtained had a good appearance and a good impact strength (60 inch/pound after one day, without cracks).
  • the results of the discolouration tests are presented in Table 1.
  • Example I powder paints and coatings were prepared. However, instead of component (1) use was made of 517 g of the polyester resin used therein. In addition, the mixer was charged with 54 g of epoxidized linseed oil containing 3 g of Santowhite
  • Example II 4.5 g of MARK PEP 4C ®
  • Example III 4.5 g of bis(2,4-ditert.butyl-6- methylphenyl)ethylphosphite
  • Example IV 4.5 g of Irgafos 12 ® .
  • Examples I-IV prove that various secondary antioxidants according to the invention give a good resistance to discolouration in several tests.
  • Example II powder paints and coatings were prepared. However, instead of the masterbatch with catalyst, 600 g of the first component were used, and further, respectively, for:
  • Example V 3 g of lithium versatate
  • Example VI 3 g of tetramethyl guanidine
  • Example VII 3 g of 1-benzyl imidazole.
  • Example IX Ultranox 626 ®
  • Example X MARK PEP 4C ®
  • Example XI Doverphos S-9228 ®
  • antioxidants according to the invention give a good resistance to 'overbake' discolouration, also if the powder paint is prepared in a manner that differs somewhat from the method used for the powder paints according to Examples I-IV.
  • Irganox 1010 is a primary
  • Irgafos 168 is tris- (2,4-di-tert. butyl- phenyl)phosphite.
  • antioxidants that have only aromatic groups do not give a good resistance to discolouration: the b* value after ordinary curing is already rather poor (>0.5) and especially the discolouration in the NO x test is very strong.
  • Powder paints and coatings were prepared analogously to Example XII, the amounts of primary and secondary antioxidants being varied as shown in Table 5.
  • Powder paints and coatings were prepared analogously to Example XII, use being made of 138 g of acid polyester resin, 8 g of masterbatch with 20 wt.% lithium versatate(10), 13 g of epoxidized linseed oil (ELO, epoxy equivalent weight: 185), 80 g of titanium dioxide (Kronos 2160 ® ), 2.4 g of flow-promoting agent, 0.8 g of Santowhite Powder ® and, respectively, for Example XVII: 1.6 g of MARK PEP 36 ® , added to the extruder
  • Example XVIII 0.8 g of MARK PEP 36 ® , dispersed in the ELO
  • Powder paints and coatings were prepared analogously to Example I, in all cases use being made of 90 g of component 1 and 10 g of component 2 (with lithium stearate), 50 g of TiO 2 , 1.5 g of Resiflow ® , 0.5 g of benzoin and 1 g of MARK PEP 36. In addition, other stabilizers were applied, as shown in Table 8. The results of the discolouration tests are also given there.
  • antioxidants according to the invention and that a good resistance to discolouration is obtained. It is also possible to use other stabilizers than primary and secondary antioxidants.
  • Example I was repeated (for Example XXIV). Also (Example XXV), before extrusion 0.16 wt.%
  • Naugard 445 ® prevents discolouration at high temperature in combination with other stabilizers.
  • the degree of discolouration was measured using a Dr. Lange Micro color (type LMG 051, method DIN 6174, Cie Lab 1976), which in all cases involves measuring the colour of a coating of 50 ⁇ m thickness on an aluminium substrate after calibration of the
  • the 200°C, 1 hr overbake test (of which the b* value after the test is given in the above examples) was conducted by cutting out a portion of the test panel and heating this portion for 1 hour at 200°C in an electrically heated furnace with air circulation. An absolute colour measurement was performed, unless indicated otherwise. Analogously the test is conducted at 240°C overbake for 10 minutes or at 220°C for 30 minutes.
  • the NO x test simulates the discolouration that can occur in a gas furnace.
  • the test specimen was placed in an air circulation furnace (capacity being 75 litre, 215°C), in which a dish with 1 g of NaNO 2 had been placed to which 1.5 g of 30% acetic acid had been added. In all cases the air supply to the furnace was shut down for 9 minutes. In the last minute fresh air was supplied, so that the NO x gases are discharged. The colour was measured as described above.
  • the test method is generally carried out by simultaneously testing a series of coatings and
  • a system known to have a good colour stability is the polyester resin Uralac ® P5012 (DSM Resins) in combination with TGIC.
  • DSM Resins polyester resin

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  • Organic Chemistry (AREA)
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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Paints Or Removers (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

L'invention concerne une composition thermodurcissante de peinture en poudre comprenant: (i) un polymère qui contient des groupes capables de réagir avec l'agent de réticulation; (ii) un agent de réticulation qui contient des groupes époxy, l'agent de réticulation comprenant au moins une chaîne aliphatique droite ou ramifiée en C5-C26 ayant un nombre de fonctions époxy supérieur à 1, le groupe époxy étant présent sur la chaîne aliphatique; (iii) au moins un catalyseur pour la réaction du polymère (i) avec l'agent de réticulation (ii); (iv) au moins un stabilisant; (v) éventuellement d'autres additifs; (vi) éventuellement un pigment ou des colorants. Le stabilisant (iv) est une phosphite qui comprend au moins un groupe ayant la formule (1). Dans cette formule, R1 est un groupe aliphatique, R2 est un groupe aliphatique ou aromatique, et R3 est un groupe aromatique. Chaque groupe aliphatique ou aromatique peut être substitué.
PCT/NL1996/000294 1995-08-03 1996-07-22 Composition de peinture en poudre WO1997006218A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU65342/96A AU6534296A (en) 1995-08-03 1996-07-22 Powder paint composition

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1000919A NL1000919C2 (nl) 1995-08-03 1995-08-03 Poederverfsamenstelling.
NL1000919 1995-08-03

Publications (1)

Publication Number Publication Date
WO1997006218A1 true WO1997006218A1 (fr) 1997-02-20

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Country Link
AU (1) AU6534296A (fr)
NL (1) NL1000919C2 (fr)
WO (1) WO1997006218A1 (fr)
ZA (1) ZA966613B (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20020023195A (ko) * 2001-12-18 2002-03-28 서용교 왕겨팽연화장치
EP3642189A4 (fr) * 2017-06-22 2021-03-17 Acs Technical Products, Inc. Compositions d'huile et de résine époxydées

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1180836A (en) * 1966-04-04 1970-02-11 Argus Chem Stabilization of Vicinal Epoxy Compounds
US4463112A (en) * 1980-02-13 1984-07-31 Leistner William E Phenylethylidene-substituted phenyl polyphosphites
GB2265377A (en) * 1992-03-11 1993-09-29 Sandoz Ltd Phosphonite-hals and phosphite-hals compounds as polymer stabilizers
EP0600546A1 (fr) * 1992-12-01 1994-06-08 Dsm N.V. Composition de liant pour peintures en poudre
EP0647674A1 (fr) * 1993-09-10 1995-04-12 Cheil Synthetics Inc. Préparation d'une composition stabilisée de polyétherester élastomère

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1180836A (en) * 1966-04-04 1970-02-11 Argus Chem Stabilization of Vicinal Epoxy Compounds
US4463112A (en) * 1980-02-13 1984-07-31 Leistner William E Phenylethylidene-substituted phenyl polyphosphites
GB2265377A (en) * 1992-03-11 1993-09-29 Sandoz Ltd Phosphonite-hals and phosphite-hals compounds as polymer stabilizers
EP0600546A1 (fr) * 1992-12-01 1994-06-08 Dsm N.V. Composition de liant pour peintures en poudre
EP0647674A1 (fr) * 1993-09-10 1995-04-12 Cheil Synthetics Inc. Préparation d'une composition stabilisée de polyétherester élastomère

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
EDS GÄCTER R. ET AL: "Taschenbuch der kunststoff-additive. 3 Ausgabe", CARL HANSER VERLAG, MÜNCHEN, XP002019726 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20020023195A (ko) * 2001-12-18 2002-03-28 서용교 왕겨팽연화장치
EP3642189A4 (fr) * 2017-06-22 2021-03-17 Acs Technical Products, Inc. Compositions d'huile et de résine époxydées

Also Published As

Publication number Publication date
AU6534296A (en) 1997-03-05
NL1000919C2 (nl) 1997-02-04
ZA966613B (en) 1997-02-18

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