Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
  • C08G59/20—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the epoxy compounds used
  • C08G59/32—Epoxy compounds containing three or more epoxy groups
  • C08G59/38—Epoxy compounds containing three or more epoxy groups together with di-epoxy compounds
• • 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
  • C09D163/10—Epoxy resins modified by unsaturated compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/02—Polycondensates containing more than one epoxy group per molecule
  • C08G59/04—Polycondensates containing more than one epoxy group per molecule of polyhydroxy compounds with epihalohydrins or precursors thereof
  • C08G59/06—Polycondensates containing more than one epoxy group per molecule of polyhydroxy compounds with epihalohydrins or precursors thereof of polyhydric phenols
  • C08G59/066—Polycondensates containing more than one epoxy group per molecule of polyhydroxy compounds with epihalohydrins or precursors thereof of polyhydric phenols with chain extension or advancing agents
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
  • C08G59/14—Polycondensates modified by chemical after-treatment
  • C08G59/1433—Polycondensates modified by chemical after-treatment with organic low-molecular-weight compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of 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
  • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
• • 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

Definitions

• the present invention relates to a powder coating composition based on an epoxy resin mixture.
• Powder coating compositions based on epoxy resins and resins containing epoxy-reactive groups are known for diverse applications.
• EP-A 119 164 describes powder coating compositions comprising an epoxy mixture consisting of a resin having an epoxy functionality of >2 and of another resin having an epoxy functionality of ⁇ 2, as well as an epoxy-reactive component, which compositions are distinguished by high storage stability and short curing times and are suitable for coating vessels on the inside.
• EP-A 857 742 it is possible to improve the flow of powder coatings based on carboxyl-containing polyesters by using a mixture of two epoxy resins, the epoxy functionalities of which differ specifically.
• This invention relates to a powder coating composition which is improved in that respect and which comprises
• the advanced epoxy resin according to component A is a product which is solid at room temperature and which is obtainable by reacting the components A1 , A2 and A3 in the presence of an advancement catalyst and, optionally, of a chain terminator.
• an advancement catalyst and, optionally, of a chain terminator.
• the glycidyl groups of the components A1 and A2 must in this reaction be in stoichiometric excess compared to the phenolic hydroxyl groups of component A3.
• Suitable components A1 are, for example, the diglycidyl ethers of bisphenol A and bisphenol F, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenylsulfone, 4,4-dihydroxydiphenylketone, 1 ,2-bis(4-hydroxyphenyl)ethane and 1 ,1 -bis(4-hydroxyphenyl)ethane. It is of course also possible to use mixtures of two or more diglycidyl ethers.
• Preferred components A1 are the diglycidyl ether of bisphenol A and the diglycidyl ether of bisphenol F.
• the resin component A2 can embrace practically any epoxy resin which is liquid, and preferably solid, at room temperature and which has an average epoxy functionality of more than 2, i.e. every epoxy resin having on average more than 2 epoxy groups per molecule, such as corresponding polyglycidyl ethers or polyglycidyl esters.
• resins suitable as component A2 are: triglycidyl isocyanurate, trimellitic acid triglycidyl ester, hexahydrotrimellitic acid triglycidyl ester, 1 ,1 ,2,2-tetrakis(4-glycidyloxyphenyl)ethane, the N,N,O-triglycidyl derivative of 4-ami- nophenol, the glycidyl ether of polyfunctional spirobisindanes, epoxyphenol novolaks and epoxycresol novolaks.
• component A2 Also suitable as component A2 are the solid mixed phases of tri- and difunctional epoxy resins described in EP-A-0 536 085.
• component A2 Preferred as component A2 are triglycidyl isocyanurate, trimellitic acid triglycidyl ester, hexahydrotrimellitic acid triglycidyl ester, epoxycresol novolaks, epoxyphenol novolaks or polyglycidyl compounds having on average more than two glycidyl groups per molecule on the basis of polyfunctional 1 ,1 '-spirobisindanes of formula I
• Z is a direct single bond or -O-; and wherein more than two of the radicals R 1 f R 2l R 3 and R 4 are -OH, -O-CO-R-CO-OH,
• R is CrC 8 alkylene, C 5 -C 8 cycloalkylene, C 6 -C 14 - arylene or partially hydrated C 6 -C 14 arylene, and the remaining radicals R 1 f R 2 , R 3 and R 4 are hydrogen, -0-CrCg.alkyl, -O-C 5 -C 8 cyclo- alkyl, -O-C 6 -C 14 aryl, partially hydrated -O-C 6 -C 1 aryl or (meth)acryloxy, and
• R 5 , R 6 , R 7 and R 8 are each independently of one another d-C 8 alkyl, C 5 -C 8 cycloalkyl, C 6 -
• Component A3 in the novel compositions may, in principle, be any of the aromatic compounds containing two phenolic hydroxyl groups that are known in the advancement method.
• Examples thereof are mononuclear diphenols, such as resorcinol, naphthalenes containing two hydroxyl groups, such as 1 ,4-dihydroxynaphthalene, biphenyls and other dinuclear aromatic compounds containing two hydroxyl groups which have an alkylene, -O-, -CO-, -S- or -SO 2 - link.
• halogenated bisphenols for example tetrabromobis- phenol A.
• Preferred components A3 are bisphenol S (bis(4-hydroxyphenyl)sulfone), 4,4'-dihydroxybi- phenyl, bisphenol F and, in particular, bisphenol A.
• the mixtures for the preparation of the advanced epoxy resin A can contain a monofunctional compound as chain terminator. This is particularly advantageous if an especially good flow behaviour is desired.
• Suitable chain terminators are monophenols and phthalimides, for example phthalimide, 3- methylphthalimide, 4-methylphthalimide or 3,3-dimethylphthalimide.
• Monophenols used are particularly preferably phenols containing one or more than one C C 12 alkyl substituent or a C 6 -C 10 aryl substituent, such as ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl, isohexyl, corresponding heptyl or octyl substituents, in particular tert-octyl, nonyl, dodecyl or phenyl substituents.
• C C 12 alkyl substituent or a C 6 -C 10 aryl substituent such as ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl
• Mono-C C ⁇ -alkylphenols are particularly preferred, especially mono-C 3 -C 8 - alkylphenols, in particular the corresponding para-alkylphenols, and p-phenylphenol.
• Other suitable monophenols are described in US-A-5,095,050.
• this invention also relates to a powder coating composition containing as component A an advanced epoxy resin prepared from a mixture which, in addition to the components A1 , A2 and A3, contains a monophenol or a phthalimide as chain terminator.
• the amounts of the components A1 , A2, A3 and, optionally, of the chain terminator used for the preparation of the advanced epoxy resin A can vary within a wide range.
• the amounts of A1 and A2 used are preferably chosen such that per 100 epoxy equivalents of the component A1 there are 1-20, particularly preferably 2-10 and, more preferably, 3-8, epoxy equivalents of the component A2.
• the amount of the component A2 used is preferably from 1.0-5.0 % by weight, more preferably from 1.25-3.0 % by weight, based on the sum of the components A1 + A2.
• the amount of the component A3 used in the advancement reaction is preferably chosen such that per 100 epoxy equivalents there are 10-90 hydroxy equivalents, particularly preferably 30-80 hydroxy equivalents and, more preferably, 50-75 hydroxy equivalents.
• the reaction of the components A1 , A2 and A3 is usefully carried out in the presence of a customary advancement catalyst.
• Suitable catalysts are disclosed, inter alia, in US-A-5,095,050, which disclosure is explicitly referred to here.
• Preferred examples of catalysts are tertiary amines, such as triethylamine, tripropylamine, tributylamine, 2-methylimid- azole, 2-phenylimidazole, N-methylmorpholine, N,N-ethylmethylpiperidinium iodide, quarter- nary ammonium compounds and alkali metal hydroxides. It is also possible to use combinations of different catalysts.
• the catalysts are used in customary catalytic amounts, i.e. generally in amounts from 0.0001 to 10 % by weight, based on the epoxy resin.
• the reaction temperatures are preferably from 80 to 200 °C, more preferably from 130 to 200 °C.
• Suitable components B of the novel compositions are, in principle, all polymers containing epoxy-reactive groups that are known in powder coating technology.
• polyesters polyacrylates or polyethers are preferred.
• Carboxyl-terminated polyesters are particularly preferred.
• the polyesters preferably have an acid number (indicated in mg KOH/g polyester) of 10 to 100 and a molecular weight of 4000 to 15000, more preferably of 6500 to 11000 (weight average M w from GPC measurement with polystyrene calibration).
• the ratio MJM n in the case of these polyesters is usually from 2 to 10.
• the polyesters are usefully solid at room temperature and have a glass transition temperature from 35 to 120 °C, preferably from 40 to 80 °C.
• polyesters are known, inter alia, from US-A-3,397,254 or EP-A-0 600 546, which disclosure is explicitly referred to here. They are reaction products of polyols with dicarboxylic acids and, optionally, with polyfunctional carboxylic acids or with the corresponding carboxy- lic anhydrides.
• Suitable polyols are, for example, ethylene glycol, the propylene glycols, 1 ,3-butanediol, 1 ,4-butanediol, neopentanediol, isopentyl glycol, 1 ,6 hexanediol, glycerol, hexanetriol, tri- methylolethane, trimethylolpropane, erythritol, pentaerythritol, cyclohexanediol or dimethylol- cyclohexane.
• Suitable dicarboxylic acids are, for example, isophthalic acid, terephthalic acid, phthalic acid, methylphthalic acids, tetrahydrophthalic acid, methyltetrahydrophthalic acids, for example 4-methyltetrahydrophthalic acid, cyclohexanedicarboxylic acids, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid or 4,4'-diphenyldicarboxylic acid, and the like.
• Suitable tricarboxylic acids are, for example, aliphatic tricarboxylic acids, such as 1 ,2,3-propanetricarboxylic acid, aromatic tricarboxylic acids, such as trimesic acid, trimellitic acid and hemimellitic acid or cycloaliphatic tricarboxylic acids, such as 6-methylcyclohex-4-ene-1 ,2,3-tricarboxylic acid.
• Suitable tetracarboxylic acids are, for example, pyromellitic acid or benzophenone-3,3',4,4'-tetracarboxylic acid.
• polyesters are particularly often based on neopentyl glycol and/or trimethylolpropane as essential alcoholic components and also on adipic acid and/or terephthalic acid and/or isophthalic acid and/or trimellitic acid as essential acid components.
• Powder coating compositions of this invention which comprise trimellitic acid-free polyesters often have a particularly good flow.
• the novel powder coating compositions preferably contain 20-80 % by weight of the component A and 80-20 % by weight of the component B, the sum of the components A + B always being 100 % by weight.
• the components A and B are preferably present in the novel powder coating compositions in such amounts that the ratio of epoxy-reactive groups to epoxy groups in the powder coating composition is from 0.5 to 1 and 2 to 1 , preferably from 0.8 to 1 and 1.2 to 1 , more preferably about 1 to 1 Jn this case, epoxy-reactive groups-containing polymers and epoxy resins are present in a weight ratio from 70 ⁇ 5 to 30 ⁇ 5 , 60 ⁇ 5 to 40 ⁇ 5 or 50 ⁇ 5 to 50 ⁇ 5 (70/30-; 60/40- and 50/50 hybrid systems).
• novel powder coating compositions can additionally contain other additives customarily used in the paint industry, such as light stabilisers, dyes, pigments, e.g. titanium dioxide, degassing agents, e.g. benzoin, and/or flow control agents.
• the novel powder coating compositions can be prepared by simply mixing the components A and B and the other components, e.g. in a ball mill. Another possibility is to melt the components together, mixing them and homogenising them, e.g. using an extrusion machine, such as a Buss co-kneader, to cool the composition and to comminute it.
• the ready powder coating mixtures preferably have a particle size in the range of 0.015 to 500 ⁇ m, more preferably of 10 to 100 ⁇ m.
• the powder coating compositions After being applied to the article to be coated, the powder coating compositions are cured at a temperature of at least about 100 °C, preferably of 150 to 250 °C. Curing takes about 5 to 60 minutes. Suitable materials for coating are all those which are stable at the temperatures necessary for curing, in particular ceramics, glass and metals.
• the glass transition temperature T g is determined via differential scanning calorimetry (DSC, 2. Flow: -30 °C to 250 °C). The melt viscosity is measured at 150 °C using an ICI cone/plate viscosimeter.
• Uralac ® P 2127 is a commercially available polyester, of DSM (NL), based on phthalic acid/ isophthalic acid/adipic acid and neopentylglycol/trimethylolpropane. Resin and polyester are used in all powder coating compositions in such amounts that an about 10 % excess of epoxy group is obtained, based on the carboxyl groups of the polyester. After premixing the components, they are further mixed using a twin screw extruder (PRISM TSE 16 PC) at 1 10°C.
• PRISM TSE 16 PC twin screw extruder
• the extrudate is cooled on a cooling roll, broken up into clumps and then rapidly ground in a centrifugal mill, of Retsch, to a fine powder which is then sieved through a sieve having a mesh width of 100 ⁇ m.
• a centrifugal mill of Retsch
• the powder is coated onto 60 ⁇ m thick Q-panels at a coating thickness of 60 ⁇ m and 65 ⁇ m, respectively.
• the panels are heated in an oven for 15 min to 200°C in order to melt and fully cure the coating.
• the surface structure is examined with respect to its texture using a "Wave Scan" profilo- meter (of Byk-Gardener).
• the k-parameters (longwave) measured are compiled in Table 2.
• k-Values (longwave) higher than about 50 indicate in this case a very uneven surface (orange peel effect) and thus an unsatisfactory flow, whereas values in the range of 30 indicate a very level surface and excellent flow.
• the impact strength r(reverse side) is determined by dropping a 2 kg die, on the bottom side of which is a ball 20 mm in diameter, bottom first from a specific height from the reverse side onto the coated area. The value indicated is the product of the weight of the die in kg and of the test height in cm at which no damage of the coating is yet found. An impact strength of > 160 cm kg is measured in all Examples.
• composition of the powder coating compositions and the measured properties are compiled in Table 2.

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

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• 2000
  • 2000-04-10 KR KR1020017011859A patent/KR20020008129A/ko not_active Application Discontinuation
  • 2000-04-10 CN CN 00806484 patent/CN1347439A/zh active Pending
  • 2000-04-10 EP EP00925188A patent/EP1175465A1/en not_active Withdrawn
  • 2000-04-10 JP JP2000612392A patent/JP2002542371A/ja active Pending
  • 2000-04-10 WO PCT/EP2000/003164 patent/WO2000063311A1/en not_active Application Discontinuation
  • 2000-04-10 BR BR0009889-2A patent/BR0009889A/pt not_active Application Discontinuation

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