EP0865472A1 - Peinture en poudre et utilisation pour le revetement interieur de contenants d'emballage - Google Patents

Peinture en poudre et utilisation pour le revetement interieur de contenants d'emballage

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Publication number
EP0865472A1
EP0865472A1 EP96939074A EP96939074A EP0865472A1 EP 0865472 A1 EP0865472 A1 EP 0865472A1 EP 96939074 A EP96939074 A EP 96939074A EP 96939074 A EP96939074 A EP 96939074A EP 0865472 A1 EP0865472 A1 EP 0865472A1
Authority
EP
European Patent Office
Prior art keywords
powder coating
particle size
particles
powder
coating
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
EP96939074A
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German (de)
English (en)
Inventor
Peter Lessmeister
Josef Rademacher
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.)
PPG Industries Ohio Inc
Original Assignee
PPG Industries Inc
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 PPG Industries Inc filed Critical PPG Industries Inc
Publication of EP0865472A1 publication Critical patent/EP0865472A1/fr
Ceased legal-status Critical Current

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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
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/62—Polymers of compounds having carbon-to-carbon double bonds
    • C08G18/6216—Polymers of alpha-beta ethylenically unsaturated carboxylic acids or of derivatives thereof
    • C08G18/622—Polymers of esters of alpha-beta ethylenically unsaturated carboxylic acids
    • C08G18/6225—Polymers of esters of acrylic or methacrylic acid
    • C08G18/6229—Polymers of hydroxy groups containing esters of acrylic or methacrylic acid with aliphatic polyalcohols
    • 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
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight 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
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
    • 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
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/48—Polyethers
    • 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
    • C08G18/00—Polymeric products of isocyanates or isothiocyanates
    • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
    • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
    • C08G18/40—High-molecular-weight compounds
    • C08G18/61—Polysiloxanes
    • 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
    • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
    • C09D175/04—Polyurethanes
    • 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
    • C08G2150/00—Compositions for coatings
    • C08G2150/20—Compositions for powder coatings
    • 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
    • C08G2390/00—Containers
    • C08G2390/40—Inner coatings for containers

Definitions

  • the present invention relates to powder coatings, in particular for the interior coating of packaging containers, based on polyhydroxy-functional resins and polyisocyanate hardeners.
  • the present invention also relates to a method for the inner coating of packaging containers and the use of powder coatings.
  • Packaging containers are generally provided with a coating on the inside, on the one hand to protect the contents from being impaired by components of the metal sheet which have been removed, and on the other hand to prevent corrosion of the metal sheet by aggressive contents.
  • thermoplastic powder coatings are often used to cover can weld seams. These products are manufactured from the appropriate thermoplastics by expensive cold grinding.
  • EP-B-119164 describes thermosetting powder coatings for covering weld seams in metal containers used to hold food or drinks are used, known. These thermosetting powder coatings contain as binder a mixture of an aromatic epoxy resin with an average of a maximum of 2 epoxy groups per molecule and an aromatic epoxy resin with an average of more than 2 epoxy groups per molecule.
  • the condensation product of the diglycidyl ether of bisphenol A with bisphenol A with an equivalent weight of 220 to 280 based on phenolic hydroxyl groups or an acidic polyester or a mixture thereof is used as the hardener.
  • EP-B-119 164 does not contain any instructions on how to use these powder coatings for the interior coating of packaging containers, nor does it contain instructions on how to modify these powder coatings for use as interior protective coatings. In particular, EP-B-119 164 does not contain any information about particle sizes and particle size distributions of the powder coatings. However, the use of these powder coatings of EP-B-119 164 with a grain size distribution which is customary for powder coatings leads to coatings which have too high a porosity in the case of the low layer thicknesses ⁇ 15 ⁇ m which are customary for interior coatings.
  • DE-PS 23 12 409 heat-hardenable, solvent-containing and solvent-free coating agents for the coating of automobile bodies, machines, systems and containers are known, which consist of an epoxy resin with more than one 1,2-epoxy group per molecule and a polyol there are more than one phenolic OH group per molecule and further conventional auxiliaries and additives.
  • a powder coating is used according to DE-PS 23 12 409 Particle size of at most 0.044 mm applied in a dry film thickness of 25 microns. Neither the particle size nor the particle size distribution of the powder coating particles is described for powder coating materials which are suitable for the production of interior coatings for packaging containers.
  • DE-PS 23 12 409 does not contain any indication that the particle size and particle size distribution can be set specifically depending on the application of the powder coating materials. Powder coatings with a maximum particle size of 44 ⁇ m and a usual grain size distribution are, however, for the production of inner coatings for packaging containers with the usual low layer thickness ⁇ . 15 ⁇ m is unsuitable because the resulting coatings have too high a porosity.
  • US Pat. No. 4,183,974 discloses powder coatings for the internal coating of cans, which also contain an epoxy resin and an amine hardener. These powder coatings have average particle sizes between 1 and 100 ⁇ m, preferably between 1 and 10 ⁇ m. Although the resulting coatings already have the required low porosity at layer thicknesses of ⁇ 13 ⁇ m, the tendency towards brittleness and the very poor elasticity of the resulting coatings in turn are in need of improvement.
  • powder coatings based on epoxy resins which, when the particle size distribution of the powder coating particles is set appropriately, are suitable both for the inner coating of packaging containers and for covering weld seams.
  • These powder coatings contain polyesters containing carboxyl groups as hardeners.
  • DE-A-42 04 266 describes powder coatings based on epoxy resins and phenolic hard materials, which, like the powder coatings known from DE-A-40 38 681, have a specific setting for the particle size distribution of the powder coating particles.
  • Powder coatings according to DE-A-40 38 681 and DE-A-42 04 266 have, such Powder coatings, however, have the specific disadvantage of insufficient resistance to acids, solvents and detergents when used as an inner coating material for packaging containers.
  • the present invention is therefore based on the object of providing powder coatings which are resistant to acids, solvents and detergents which, when used for the inner coating of packaging containers, also meet the requirements when applied with thin layers of ⁇ 15 ⁇ m that are usually placed on container coatings.
  • these inner coatings should not be porous (determined with the help of the so-called Enamelrat test), show good adhesion to the substrate and have a high elasticity.
  • the powder coatings should be capable of being cured during the short drying times customary for container coating.
  • the powder coating has such a particle size distribution that
  • the maximum particle size for at least 99% by mass of the powder coating particles is ⁇ 100 ⁇ m
  • the average particle size of the powder coating particles is between 5 and 20 ⁇ m and
  • the invention relates to methods for the inner coating of packaging containers, in which these powder coatings are applied.
  • the invention also relates to the use of the powder coatings for the interior coating of packaging containers.
  • the property profile and thus the intended use of powder coatings based on polyhydroxy-functional resins and isocyanate hardeners can be controlled in a targeted manner by setting a special particle size distribution.
  • the inventive Powder coatings can be hardened quickly, are easy to handle and easy to apply.
  • the powder coatings according to the invention are distinguished by the fact that coatings with only a very small layer thickness of ⁇ 15 ⁇ m have the properties required by the container manufacturers for internal coatings. In particular, these coatings have the required low porosity even with a small layer thickness of ⁇ 15 ⁇ m.
  • these coatings are distinguished by good adhesion, high flexibility and excellent resistance to acids, solvents and detergents.
  • the polyhydroxy-functional resins (component A) used in the powder coatings according to the invention are solid polymer resins with a hydroxyl number between 5 and 200 mg KOH / g.
  • Polyhydroxy-functional resins A which can be used are, for example, polyester, polyether, polyurethane, polyacrylate and / or polysiloxane resins with weight-average molecular weights M w between 500 and 200,000, preferably between 1,000 and 100,000 daltons.
  • Suitable polyhydroxy-functional polyesters A are obtained, for example, by esterification of organic dicarboxylic acids or their Anhydrides are prepared with organic diols and / or polyols, the formation of branching points at the expense of free hydroxyl groups in the polyester having to be suppressed.
  • Aliphatic, cycloaliphatic saturated or unsaturated and / or aromatic dibasic carboxylic acids, and their anhydrides and / or their esters are preferably used as dicarboxylic acids. Examples include: phthalic acid (anhydride), isophthalic acid, terephthalic acid, tetrahydro- or
  • Hexahydrophthalic acid (anhydride), endomethylene tetrahydrophthalic acid, succinic acid, glutaric acid, sebacic acid, azelaic acid, fumaric and maleic acid.
  • the most common are isophthalic acid and phthalic acid (anhydride).
  • Aliphatic, cycloaliphatic and / or araliphatic alcohols having 1 to 6, preferably 1 to 4, hydroxyl groups bonded to non-aromatic carbon atoms are preferably used as the polyol building blocks.
  • Examples include: ethylene glycol, 1,2-1,3 and 1,3-propanediol, 1,2-1,3-butanediol and 1,4, 2-ethylpropanediol-1,3,2-ethylhexanediol-1,3 , 1, 3-neopentyl glycol, 2,2-dimethylpentanediol-1, 3, hexanediol-1, 6, cyclohexanediol-1, 2 and -1,4, 1,2- and 1,4-bis (hydroxymethyl) cyclohexane, adipic acid bis (ethylene glycol ester), ether alcohols such as di- and triethylene glycol, dipropylene glycol, perhydrogenated bisphenols, butanet
  • Preferred alcohols are: glycerol, trimethylolpropane, neopentyl glycol and pentaerythritol.
  • Polyalkylene ethers with, for example, 2 to 6 carbon atoms and at least one free hydroxyl group per alkylene unit can be used as polyether polyols A, the number of repeating alkylene units per polymer molecule being between 2 and 100, preferably between 5 and 50. Examples are poly-2-hydroxy-l, 3-propylene oxide, poly-2 or poly-3-hydroxy-l, 4-butylene oxide.
  • polyurethane polyols can be, for example, the aliphatic, cycloaliphatic and / or araliphatic alcohols already described above with 1 to 6, preferably 1 to 4, hydroxyl groups bonded to non-aromatic carbon atoms.
  • polyester polyols themselves can also be used as polyurethane building blocks, it being necessary to ensure that the molecular weight limits M w mentioned at the outset of 500 to 200,000, preferably 1,000 to 100,000, daltons are not exceeded in the synthesis of the polyurethane polyol, for example due to Networking.
  • Aliphatic and / or cycloaliphatic and / or aromatic diisocyanates can be used as the polyisocyanate component in the synthesis of the polyurethane polyols A.
  • aromatic diisocyanates are phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, biphenylene diisocyanate, naphthylene diisocyanate and diphenylmethane diisocyanate.
  • cycloaliphatic polyisocyanates examples include isophorone diisocyanate, cyclopentylene diisocyanate and the hydrogenation products of aromatic diisocyanates such as cyclohexylene diisocyanate, methylcyclohexylene diisocyanate and dicyclohexylmethane diisocyanate.
  • aliphatic diisocyanates examples include tri- methylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, propylene diisocyanate, ethyl ethylene diisocyanate, dimethyl ethyl diisocyanate, methyl trimethylene diisocyanate and trimethyl hexane diisocyanate.
  • Another example of an aliphatic diisocyanate is tetramethylxylene diisocyanate.
  • polyhydroxy-functional polyacrylates A are those which, as comonomer units, preferably contain hydroxyalkyl esters of acrylic acid, methacrylic acid or another alpha, beta-ethylenically unsaturated carboxylic acid. These esters can be derived from an alkylene glycol esterified with the acid, or they can be obtained by reacting the acid with an alkylene oxide.
  • Hydroxyalkyl esters of (meth) acrylic acid in which the hydroxyalkyl group contains up to 4 carbon atoms, or mixtures of these hydroxyalkyl esters are preferably used as the hydroxyalkyl esters.
  • examples include: 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate or 4-hydroxybutyl (meth) acrylate.
  • the polyacrylate polyols can contain, for example, aliphatic, cycloaliphatic, aromatic and / or araliphatic (meth) acrylates with up to 20 carbon atoms in the ester radical, such as, for example: methyl (meth) acrylate, ethyl (meth) acrylate, pro pyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, tert.-tyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate , Lauryl (meth) acrylate, cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, cycloctyl (meth) acrylate, phenyl (meth) acrylates
  • Vinylaromatic hydrocarbons such as styrene, alpha-alkylstyrene and vinyltoluene, and also (meth) acrylamides and / or (meth) acrylonitrile can also be used as comonomer units in the polyacrylate polyols A.
  • the polyhydroxy-functional polysiloxanes A are preferably organopolysiloxanes which have hydroxy-functional substituents. Examples include methylhydroxyethylpolysiloxane, methyl 3-hydroxypropylpolysiloxane or ethyl 3-hydroxypolysiloxane. Such organopolysiloxanes can also be contained as oligomeric and / or polymeric building blocks in the polyhydroxy-functional resins A described above. For the organopolysiloxanes mentioned, see, for example, Ullmann's Encyclopedia of Industrial Chemistry, 4th Edition, Volume 21, pages 520 to 510, Verlag Chemie, Weinheim, Deerfield Beach, Basel, 1982.
  • Suitable as hard component B are aliphatic and / or cycloaliphatic and / or aromatic polyisocyanates, preferably in the solid state at the application temperature.
  • aromatic polyisocyanates are phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, biphenylene diisocyanate, naphthylene diisocyanate and diphenylmethane diisocyanate.
  • cycloaliphatic polyisocyanates examples include isophorone diisocyanate, cyclopentylene diisocyanate and the hydrogenation products of aromatic diisocyanates such as cyclohexylene diisocyanate, methylcyclohexylene diisocyanate and dicyclohexylmethane diisocyanate.
  • Aliphatic diisocyanates are compounds of the formula OCN- (CR3 2j r-NCO
  • r is an integer from 2 to 20, in particular 6 to 8 and R 3 , which may be the same or different, represents hydrogen or a lower alkyl radical having 1 to 8 carbon atoms, preferably 1 or 2 carbon atoms.
  • R 3 represents hydrogen or a lower alkyl radical having 1 to 8 carbon atoms, preferably 1 or 2 carbon atoms.
  • trimethylene diisocyanate trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, propylene diisocyanate, ethylethylene diisocyanate, dimethylethyl diisocyanate, methyl trimethylene diisocyanate and trimethylhexane diisocyanate.
  • trimethylene diisocyanate trimethylene diisocyanate
  • tetramethylene diisocyanate pentamethylene diisocyanate, hexamethylene diisocyanate
  • propylene diisocyanate
  • the hardener component B can also contain a proportion of polyisocyanates with functionalities over two, e.g. Triisocyanates.
  • Products which have been obtained as triisocyanates are those which are formed by trimerization or oligomerization of diisocyanates or by reaction of diisocyanates with compounds containing polyfunctional OH or NH groups. These include, for example, the biuret of hexamethylene diisocyanate and water, the isocyanurate of hexamethylene diisocyanate or the adduct of isophorone diisocyanate with trimethylolpropane.
  • the average functionality can optionally be reduced by adding monoisocyanates. Examples of such chain terminating monoisocyanates are phenyl isocyanate, cyclohexyl isocyanate and stearyl isocyanate.
  • the polyhydroxy-functional resin A is usually used in the powder coatings according to the invention in an amount of 10 to 90% by weight, preferably 29 to 80% by weight, in each case based on the total weight of the powder coating.
  • the hardener component B is usually used in the powder coatings according to the invention in an amount of 10 to 80% by weight, preferably 10 to 50% by weight, in each case based on the total weight of the powder coating.
  • the powder coating materials according to the invention contain at least one hardening catalyst, usually in an amount of from 0.01 to 5.0% by weight, preferably from 0.05 to 2.0% by weight, based in each case the total weight of the powder coating.
  • the catalyst is advantageously selected from the group of compounds which catalyze the conversion of isocyanate with hydroxyl groups to urethane groups, such as, for example, dibutyltin dilaurate, dibutyltin maleate, or mixtures of various of the catalysts mentioned.
  • the powder coatings according to the invention can also contain 0 to 40% by weight, preferably 15 to 25% by weight, of fillers (component D).
  • fillers for example titanium dioxide, such as Kronos 2160 from Kronos Titan, Rutil® 902 from Du Pont and RC 566 from Sachtleben, barium sulfate and silicate-based fillers such as talc, kaolin, Magnesium aluminum silicates, mica and the like are used. Titanium dioxide and fillers of the quartz sand type are preferably used.
  • the powder coating materials of the invention may optionally contain from 0.01 to 10% by weight, preferably 0.1 to 2% by weight, based on the total weight of the powder coating material, of further auxiliaries and additives. Examples of these are leveling agents, trickles ⁇ aids, venting agents such as benzoin, pigments or the like.
  • the powder coating is produced according to the known methods (see, for example, product information from BASF Lacke + Wegner + Wegner AG, "Pulverlacke", 1990) by homogenizing and dispersing, for example using an extruder, screw kneader, etc. It is essential to the invention that the powder coatings, after their production, are adjusted to a grain size division adapted to the intended use by grinding and, if appropriate, by sifting and sieving.
  • the maximum particle size of the powder coating particles is ⁇ 100 ⁇ m, preferably ⁇ 60 ⁇ m and particularly preferably ⁇ 40 ⁇ m).
  • the average particle size of the powder coating particles is between 5 to 20 ⁇ m, particularly preferably between 5 to 12 ⁇ m. Furthermore, it is Significantly that when using the powder coatings for the inner coating of the packaging containers, the grain size distribution is adjusted so that the slope S of the grain distribution curve at the turning point>. 100, preferably> . 150 and particularly preferred> . Is 200.
  • powder coatings are very particularly preferably used in which the steepness S of the grain size distribution curve at the turning point . > 300 is.
  • the slope S is defined as the limit for f (x 2 ) - f (x ⁇ ) towards zero of (f (x 2 ) - f (x ⁇ _)) / lg ((X2 / X1)) at the point of inflection of the grain distribution curve.
  • the grain distribution curve represents the plot of the cumulative mass percent (f (x)) against the absolute grain diameter (x), the grain diameter being represented on a logarithmic scale and the accumulated mass percent on a linear scale. Powder coatings which have only a small proportion of very fine particles (particle size ⁇ 5 ⁇ m) and at the same time only a very small proportion of coarse powder coating particles (particle size> 25 ⁇ m) are therefore particularly suitable for use as the inner coating of packaging containers. ie have the narrowest possible grain size distribution.
  • the respective particle size distribution of the powder coating materials is adjusted using suitable grinding units, if appropriate in combination with suitable ones
  • the packaging containers which are coated with the powder coating materials according to the invention can consist of a wide variety of materials, have a wide variety of sizes and shapes and have been produced by various processes.
  • metallic containers are coated with the powder coatings according to the invention.
  • These metal containers can have been produced, for example, by first rolling metal sheet and then connecting it by welding, bordering or edging. The end pieces, such as lids, can then be attached to the cylinder thus created.
  • the powder coatings according to the invention are used for the inner coating of the container body.
  • deep-drawn metal containers can also be coated on the inside with the powder coatings according to the invention.
  • the powder coating materials are also suitable for coating can lids and the bottom of the can.
  • the packaging containers can consist of a wide variety of materials, such as aluminum, black plate, tin plate and various iron alloys, which are optionally provided with a passivation layer based on nickel, chromium and tin compounds.
  • the application is carried out according to known methods, such as are described, for example, in US Pat. No. 4,183,974.
  • the powder coating particles are electrostatically charged by friction (triboelectricity) or by electrostatic charging (corona process).
  • the powder coatings are usually applied in a layer thickness ⁇ 15 ⁇ m, preferably from 10 to 14 ⁇ m. Even with these small layer thicknesses, the coatings meet the requirements usually placed on such films. Of course, the powder coatings can also be applied in higher layer thicknesses.
  • the packaging container the inside of which has been provided with the powder coating according to the invention, is then subjected to a heat treatment in order to harden the powder coating.
  • This heat treatment can be done in different ways.
  • the containers are often challenged by a continuous furnace.
  • the powder coatings generally harden completely at object temperatures between 180 and 350 degrees C within a time of 5 to 300 s.
  • the continuous furnace can be operated at a constant temperature or have a temperature profile that is set according to the respective circumstances.
  • polyester-polyol (Crelan® U 502 from Bayer AG)
  • the maximum particle size for at least 99 percent by mass of the particles is ⁇ 100 ⁇ m, the average particle size is 9 ⁇ m.
  • the steepness S at the turning point of the grain distribution curve is 250.
  • this powder coating 1 was applied to a tinned container body (2.8 mg layer / m 2 ) in a layer thickness of 15 ⁇ m and baked for 30 s at an object temperature of 280 ° C. The coating thus obtained was a
  • Test medium 1% aqueous sodium lauryl sulfate solution
  • test medium 3% aqueous acetic acid
  • the grain size distribution was set according to Example 1.
  • the powder coating 2 was applied according to Example 1 on a can body by means of suitable equipment, baked and then subjected to an enamel rater test.
  • the coating thus obtained was subjected to a load test (4 weeks storage in test medium at room temperature) in various test media. Immediately after the load, the detachment of the coating or the swelling by the test medium (visual), adhesion and elasticity were checked. The results are summarized in Table 2.
  • T-Bend 2 TO TO TO TO TO TO - - -
  • a powder coating was prepared from the components given in Example 1 analogously to the procedure in Example 1.
  • a particle size distribution customary for powder coatings was now set on a classifier mill.
  • the maximum particle size of this powder coating 3 is for at least 99% by mass of the particles ⁇ 100 ⁇ m.
  • the average particle size is 35 ⁇ m.
  • the slope S at the inflection point of the grain distribution curve is 135.
  • This powder coating 3 was made using a suitable
  • the powder coating 3 can therefore not be applied without pores in the thin layers required by the packaging industry. Furthermore, these high layers of powder coating burst very quickly from the container sheet in the beading process. Comparative Example 3
  • a powder coating was prepared from the components given in Example 1 analogously to the procedure in Example 1.
  • the powder coating was ground on a classifier mill in such a way that the maximum particle size of this powder coating 3 for at least 99% by mass of the particles . Is 50 ⁇ m (usual fine grinding).
  • the average particle size is 15 ⁇ m.
  • the slope S at the inflection point of the grain distribution curve is 92.
  • This powder coating 4 showed very poor fluidization and application behavior in standard application units. Coating can bodies was only possible with great difficulty. There were blockages in the powder coating conveyors. The powder coating 4 tended to form strong agglomerates, so that the coating had a clearly uneven layer thickness. Despite these difficulties, this powder coating 4 was applied in various layer thicknesses to a container body (opening 73 mm, body length 110 mm), baked for 30 s at an object temperature of 280 ° C. and then subjected to the enamel rater test described in Example 1. The following results were obtained:
  • This powder coating 4 thus forms in comparison to the powder coating 3 at significantly reduced Layer thicknesses of non-porous films, however, these layer thicknesses are still significantly above the thin layer thickness of ⁇ 15 ⁇ m required by the packaging container manufacturers. Furthermore, in contrast to the powder coating 1, this powder coating 4 has
  • Example 1 shows a very poor application behavior.
  • the Rulverlack 4 obtained according to Comparative Example 3 was sieved over a 32 ⁇ m carbon fiber sieve.
  • the powder coating 5 thus obtained has a maximum particle size for at least 99 percent by mass

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Paints Or Removers (AREA)
  • Polyurethanes Or Polyureas (AREA)

Abstract

L'invention concerne une peinture en poudre, notamment pour le revêtement intérieur de contenants d'emballage, caractérisée en ce que 1) elle contient au moins une résine à fonction polyhydroxy avec un indice d'hydroxyle compris entre 5 et 200 mg KOH/g et au moins un durcisseur de polyisocyanate avec au moins un groupe isocyanate par molécule et en ce que 2) elle présente une répartition granulométrique telle qu'au moins 90 % en masse des particules de peinture en poudre possèdent une dimension de particule comprise entre 1 et 60 νm, que la dimension maximale des particules de peinture en poudre est inférieure ou égale à 100 νm, que la dimension moyenne de particules de peinture en poudre est comprise entre 5 et 20 νm et que la pente de la courbe de répartition granulométrique est supérieure ou égale à 100 au point d'inflexion.
EP96939074A 1995-12-06 1996-11-16 Peinture en poudre et utilisation pour le revetement interieur de contenants d'emballage Ceased EP0865472A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE1995145424 DE19545424A1 (de) 1995-12-06 1995-12-06 Pulverlack und dessen Verwendung zur Innenbeschichtung von Verpackungsbehältern
DE19545424 1995-12-06
PCT/EP1996/005050 WO1997020897A1 (fr) 1995-12-06 1996-11-16 Peinture en poudre et utilisation pour le revetement interieur de contenants d'emballage

Publications (1)

Publication Number Publication Date
EP0865472A1 true EP0865472A1 (fr) 1998-09-23

Family

ID=7779287

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96939074A Ceased EP0865472A1 (fr) 1995-12-06 1996-11-16 Peinture en poudre et utilisation pour le revetement interieur de contenants d'emballage

Country Status (6)

Country Link
EP (1) EP0865472A1 (fr)
JP (1) JP2000502125A (fr)
BR (1) BR9611580A (fr)
CA (1) CA2235763A1 (fr)
DE (1) DE19545424A1 (fr)
WO (1) WO1997020897A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1083300C (zh) * 1996-06-14 2002-04-24 巴斯福涂料股份公司 金属带材涂漆方法
DE10349811A1 (de) 2003-10-24 2005-05-25 Bayer Materialscience Ag Beschichtungen für Nahrungsmittelbehälter
DE102004060798A1 (de) 2004-12-17 2006-06-29 Bayer Materialscience Ag Wässrige Beschichtungen für Nahrungsmittelbehälter

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3401050A (en) * 1965-05-17 1968-09-10 Goodyear Tire & Rubber Method of forming a protective inner liner on a metal container
DE1965740C3 (de) * 1969-12-31 1979-11-22 Bayer Ag, 5090 Leverkusen Verfahren zur Herstellung von pulverisierbaren Acryl-Harzen
US5379947A (en) * 1993-11-09 1995-01-10 Basf Corporation Process for producing a powder coating composition

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9720897A1 *

Also Published As

Publication number Publication date
CA2235763A1 (fr) 1997-06-12
BR9611580A (pt) 1999-07-13
WO1997020897A1 (fr) 1997-06-12
JP2000502125A (ja) 2000-02-22
DE19545424A1 (de) 1997-06-12

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