EP0601079A1 - Compositions pulverulentes pour revetements thermodurcissables - Google Patents

Compositions pulverulentes pour revetements thermodurcissables

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Publication number
EP0601079A1
EP0601079A1 EP92919099A EP92919099A EP0601079A1 EP 0601079 A1 EP0601079 A1 EP 0601079A1 EP 92919099 A EP92919099 A EP 92919099A EP 92919099 A EP92919099 A EP 92919099A EP 0601079 A1 EP0601079 A1 EP 0601079A1
Authority
EP
European Patent Office
Prior art keywords
powder coating
coating composition
thermosetting powder
residues
adduct
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
EP92919099A
Other languages
German (de)
English (en)
Inventor
Robert Boyd Barbee
Brian Steven Phillips
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.)
Eastman Chemical Co
Original Assignee
Eastman Kodak Co
Eastman Chemical Co
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 Eastman Kodak Co, Eastman Chemical Co filed Critical Eastman Kodak Co
Publication of EP0601079A1 publication Critical patent/EP0601079A1/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
    • C08G18/42—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
    • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
    • C08G18/4202—Two or more polyesters of different physical or chemical nature
    • 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
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/72—Polyisocyanates or polyisothiocyanates
    • C08G18/77—Polyisocyanates or polyisothiocyanates having heteroatoms in addition to the isocyanate or isothiocyanate nitrogen and oxygen or sulfur
    • C08G18/78—Nitrogen
    • C08G18/79—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates
    • C08G18/798—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates containing urethdione groups
    • 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
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/72—Polyisocyanates or polyisothiocyanates
    • C08G18/80—Masked polyisocyanates
    • C08G18/8003—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen
    • C08G18/8006—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen with compounds of C08G18/32
    • C08G18/8009—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen with compounds of C08G18/32 with compounds of C08G18/3203
    • C08G18/8012—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen with compounds of C08G18/32 with compounds of C08G18/3203 with diols
    • 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

Definitions

  • This invention relates to certain novel thermo— setting powder coating compositions. More particularly, this invention provides a composition comprising a blend of an aromatic polyester, and aliphatic polyester, and a self—blocked polyisocyanate.
  • Thermosetting powder coating compositions are used extensively to produce durable protective coatings on various materials.
  • Thermosetting coatings when compared to coatings derived from thermoplastic composi ⁇ tions, generally are tougher, more resistant to solvents and detergents, have better adhesion to metal substrates, and do not soften when exposed to elevated temperatures.
  • the curing of thermosetting coatings has created problems in obtaining coatings which have, in addition to the above—stated desirable characteristics, good smoothness and flexibility.
  • Coatings prepared from thermosetting powder composi— tions upon the application of heat, may cure or set prior to forming a smooth coating, resulting in a relatively rough or non-uniform finish.
  • thermo ⁇ setting coatings to be applied from organic solvent systems which are inherently undesirable because of the environmental and safety problems sometimes occasioned by the evaporation of the solvent system.
  • Solvent—based coating compositions also suffer from the disadvantage of relatively poor percent utilization, i.e., in some modes of application, only 60 percent or less of the solvent—based coating composition being applied contacts the article or substrate being coated. Thus, a substantial portion of solvent—based coatings can be wasted since that portion which does not contact the article or substrate being coated obviously cannot be reclaimed.
  • the polymeric materials constituting powder coating composi ⁇ tions must melt within a particular temperature range to permit timely and ample flow of the polymeric material prior to the occurrence of any significant degree of curing, i.e., cross—linking.
  • Powder coating composi— tions which possess the requisite melting range provide smooth and glossy coatings upon being heated to cure the compositions.
  • coatings derived from thermosetting coating compositions should exhibit or possess good impact strength, hard— ness, flexibility, and resistance to solvents and chemicals. For example, good flexibility is essential for powder coating compositions used to coat sheet (coil) steel which is destined to be formed or shaped into articles used in the manufacture of various household appliances and automobiles wherein the sheet metal is flexed or bent at various angles.
  • amorphous polyesters utilized in powder coating formulations desirably possess a glass transi ⁇ tion temperature (Tg) higher than the storage tempera ⁇ tures to which the formulations will be exposed.
  • Semi- crystalline polyesters and blends thereof with amorphous polyesters also may be utilized in powder coating formulations.
  • semi—crystalline polyesters desirably possess a significant degree of crystallinity to prevent caking or sintering of the powder for a reasonable period of time prior to its application to a substrate.
  • Semi-crystalline polyesters used in powder coating formulations also must have melting temperature low enough to permit the compounding of the powder coating formulation without causing the cross—linking agent to react prematurely with the polyesters.
  • the lower melting temperature of the semi- crystalline polyester also is important to achieving good flow of the coating prior to curing and thus aids the production of smooth and glossy coatings.
  • a coated article typically is heated at a temperature in the range of about 325 to 400°F (163-204°C) for up to about 20 minutes causing the coating particles to melt and flow followed by reaction of the cross—linking (curing) agent with the polyester.
  • the degree of curing may be determined by the methyl ethyl ketone rub test described hereinbelow.
  • a thermosetting coating is considered to be completely or adequately cross—linked if the coating is capable of sustaining 200 double rubs. It is apparent that the use of lower temperatures and/or shorter curing times to produce adequately cross-linked coatings is very advantageous since higher production rates and/or lower energy costs can be achieved thereby.
  • the products marketed as e—caprolactam—blocked isophorone diisocyanate may consist primarily of the blocked, difunctional, monomeric isophorone diisocyanate, i.e., a mixture of the cis and trans iso ers of 3—isocyanatomethyl—3,5,5— tri ethylcyclohexylisocyanate, the blocked, difunctional dimer thereof, the blocked, trifunctional trimer thereof or a mixture of the monomeric, di eric and/or trimeric forms.
  • the blocked polyisocyanate compound used as the cross—linking agent may be a mixture consisting primarily of the e—caprolactam—blocked, difunctional, monomeric isophorone diisocyanate and the e—caprolactam—blocked, trifunctional trimer of isophorone diisocyanate.
  • the reaction of the isocyanato groups with the blocking compound is reversible at elevated temperatures, e.g., about 150°C and above, at which temperature the isocyanato groups are available to react with the hydroxyl groups present on the polyester to form urethane linkages, thereby cross—linking or curing the coating composition.
  • e—caprolactam is liberated from the powder coating compositions.
  • adducts of the 1,3-diazetidine—2,4—dione dimer of isophorone diisocyanate and diols have been developed for use as cross—linking agents in powder coating compositions.
  • Such adducts and powder coating composi ⁇ tions containing the adducts are described in the literature such as, for example, U. S. Patent 4,413,079, German OLS 3,328,133, and the Journal of Chromatography, 472 (1989) 175—195.
  • an aliphatic polyester derived from 1,4—cyclohexanedicarboxylic acid and 1,4— butanediol can be blended with an aromatic polyester and formulated into a powder coating with a self—blocked isocyanate and which has better cure and physical properties than coatings not containing the aliphatic polyester.
  • Figure 1 is a graph of QUV weathering of the powder coatings of Comparative Example 1, and Examples 2 and 3, all of which are described in the Experimental Section below.
  • "QUV" weathering is performed by exposing the coating to high intensity ultraviolet radiation, thereby simulating performance of the coating in the presence of sunlight, albeit on an accelerated basis.
  • the plot indicated by bold dots is the coating of Comparative
  • Example 1 the plot indicated by open—circled points is the coating of Example 2; and the plot indicated by "triangle—points” is the coating of Example 3.
  • Percent gloss retention at 60° is plotted versus time in hours. This plot illustrates the unexpectedly superior weathering properties of the compositions of the present invention relative to compositions containing no aliphatic polyester component.
  • the present invention provides a novel thermo ⁇ setting powder coating composition comprised of a blend of an aromatic polyester and an aliphatic polyester, poly(tetramethylene trans—1,4—cyclohexane—dicarboxylate) and a self—blocked crosslinking agent.
  • the cross- linking agent is an adduct of 1,3—diazetinine—2,4—dione and a diol.
  • thermosetting powder coating composition which comprises an intimate blend of
  • a novel blend of polymers containing free hydroxy groups comprised of: (a) about 10 to about 80 weight percent of an aromatic polyester having a glass transition temperature (T g ) of greater than about 40"C., a hydroxyl number of about 20 to 200 and an inherent viscosity of about 0.1 to about 0.5; and
  • R 1 is a divalent l—methylene—l,3,3—trimethyl—
  • 5-cyclohexyl radical i.e., a radical having the structure
  • R 2 is a divalent aliphatic, cycloaliphatic, araliphatic or aromatic residue of a diol; and X is a 1,3—diazetidine—2,4—dionediyl radical, i.e., a radical having the structure
  • the ratio of NCO to OH groups in the formation of the adduct is about 1:0.5 to 1:0.9
  • the mole ratio of diazetidinedione to diol is from 2:1 to 6:5
  • the content of free isocyanate groups in the adduct is not greater than 8 weight percent and the adduct has a molecular weight of about 500 to 4000 and a melting point of about 70 to 130°C.
  • the powder coatings of the present invention provide coatings with improved impact strength, improved flexibility, improved weatherability, and a higher degree of cure at a lower cure temperature than a system without the aliphatic polyester.
  • both the aromatic poly— ester and the aliphatic polyester may be produced using well known polycondensation procedures.
  • Poly(tetramethylene trans—1,4—cyclohexanedicar— boxylate) may be prepared from 1,4—butanediol and the acid or diester of trans—1,4—cyclohexanedicarboxylic acid.
  • diester it is preferred that some excess glycol is utilized during the ester interchange reaction and is removed under reduced pressure until the desired viscosity is obtained.
  • the preferred aliphatic poly(tetramethylene trans- 1,4-cyclohexanedicarboxylate) polyester has a T m in the range of about 110° to 160°C, a hydroxyl number in the range of about 25 to 65, an acid number of not more than 10, and an inherent viscosity of about 0.10 to 0.40.
  • the aliphatic polyester component may also contain a polyol branching agent such as trimethylolpropane, to increase the crosslink density of the coating.
  • a polyol branching agent such as trimethylolpropane
  • up to about 10 mole percent of the 1,4—butanediol is replaced with a glycol having 2 to 12 carbon atoms.
  • glycols examples include ethylene glycol, propylene glycol, 1,3—propanediol, 2,4—dimethyl—2—ethylhexane-1,3—diol, 2,2—dimethyl-1,3—propanediol, 2—ethyl—2—butyl—1,3- propanediol, 2—ethyl—2—isobutyl—1,3—propanediol, 1,3- butanediol, 1,5—pentanediol, 1,6-hexanediol, thio— diethanol, 1,2—, 1,3- and 1,4—cyclohexanedimethanol, 2,2,4,4—tetramethy1—1,3—cyclobutanediol, 1,4—xylylene— diol and the like.
  • trans—1,4—eyelohexane- dicarboxylic acid When trans—1,4—eyelohexane- dicarboxylic acid is referred to herein, it is intended to denote a mixture comprised of at least 70% trans isomer.
  • the preferred aromatic polyester component of the composition provided by this invention has a T g greater than 55°C, a hydroxyl number in the range of about 25 to 80, an acid number of not more than 15, and an inherent viscosity of about 0.15 to 0.4.
  • the aromatic polyester component preferably is comprised of (1) diacid residues of which at least 50 mole percent are terephthalic acid residues, (2) glycol residues of which at least 50 mole percent are derived from 2,2—dimethy1— 1,3-propanediol and (3) up to 10 mole percent, based on the total moles of (2) and (3) , of trimethylolpropane residues.
  • diacid residues of which at least 50 mole percent are terephthalic acid residues
  • glycol residues of which at least 50 mole percent are derived from 2,2—dimethy1— 1,3-propanediol and (3) up to 10 mole percent, based on the total moles of (2) and (3) , of trimethylolpropane residues.
  • These preferred aromatic polyesters are commercially available under the tradenames Rucote 107 and Cargill Resin 3000.
  • a further preferred aliphatic poly(tetramethylene trans—1,4—cyclohexanedicarboxylate) has a hydroxyl number of about 20 to 200, and an inherent viscosity of about 0.1 to 0.5; wherein up to 10 mole percent of the polyol residues are comprised of trimethylolpropane residues.
  • compositions of the present invention comprise a blend of about 10 to 80 weight percent of the aromatic polyester and about 20 to 90 weight percent of the aliphatic polyester.
  • the blend of polymers containing free hydroxy groups provided by this invention is preferably comprised of about 20 to 75 weight percent of the aromatic polyester and 25 to 80 weight percent of the aliphatic polyester. It should be thus appreciated that components (1) (a) and (1) (b) will always total 100 percent.
  • the adducts of the 1,3—diazetidine-2,4—dione dimer of isophorone diisocyanate and a diol are prepared according to the procedures described in U.S. Patent 4,413,079, incorporated herein by reference, by reacting the diazetidine dimer of isophorone diisocyanate, preferably free of isocyanurate trimers of isophorone diisocyanate, with diols in a ratio of reactants which gives as isocyanto:hydroxyl ratio of about 1:0.5 to 1:0.9, preferably 1:0.6 to 1:0.8.
  • the adduct preferably has a molecular weight of 1450 to 2800 and a melting point of about 85 to 120°C.
  • the preferred diol residue (R 2 ) is a C 2 —C Z diol, most preferably the residue of 1,4— butanediol.
  • Such an adduct is commercially available under the name H ls BF1540.
  • the amount of the cross—linking adduct present in the compositions of this invention can be varied depending on several factors such as those mentioned hereinabove relative to the amounts of aromatic polyester and aliphatic polyester utilized.
  • the amount of cross—linking adduct which will effectively cross—link the hydroxy—containing polymers to produce coatings having a good combination of properties is in the range of about 5 to 30 weight percent, preferably 10 to 25 weight percent, based on the total weight of the aromatic polyester, the aliphatic polyester and the cross—linking compound.
  • the cross—linking component of the compositions may contain a minor amount, e.g., up to about 30 weight percent based on the total weight of the cross—linking component, of another blocked polyisocyanate such as those which are based on isophorone diisocyanate blocked with e—caprolactam, commercially available as H ⁇ ls B1530, Ruco NI—2 and Cargill 2400, and phenol— blocked hexamethylene diisocyanate.
  • e—caprolactam commercially available as H ⁇ ls B1530, Ruco NI—2 and Cargill 2400, and phenol— blocked hexamethylene diisocyanate.
  • the presence of minor amounts of such blocked polyisocyanates has been found to provide good cross—linking at temperatures as low as 325°F (163°C) with the liberation of very minor amounts of the blocking agent, e.g., e—caprolactam.
  • the powder coating compositions of our invention may be prepared from the compositions described herein by dry—mixing and then melt—blending the aromatic polyester, the aliphatic polyester and the cross—linking adduct, along with other additives commonly used in powder coatings, and then grinding the solidified blend to a particle size, e.g., an average particle size in the range of about 10 to 300 microns, suitable for producing powder coatings.
  • the ingredients of the powder coating composition may be dry blended and then melt blended in a ZSK twin—screw extruder at 90 to 130°C, granulated and finally ground.
  • the melt blending should be carried out at a temperature sufficiently low to prevent the conversion of the cross—linking adduct to a reactive form and thus avoid premature cross—linking.
  • the amorphous and semi- crystalline polyesters may be blended prior to the incorporation therein of the cross—linking agent.
  • Typical of the additives which may be present in the powder coating compositions include benzoin, used to reduce entrapped air or volatile ⁇ , flow aids or flow control agents which aid the formation of a smooth, glossy surface, catalysts to promote the cross—linking reaction between the isocyanate groups of the cross— linking agent, and the hydroxyl groups on the polymers, stabilizers, pigments, and dyes.
  • a catalyst to aid the cross—linking reaction, e.g., in an amount of about 0.05 to 2.0 weight percent cross- linking catalyst based on the total weight of the amorphous and semi—crystalline polyesters and the cross- linking agent.
  • Suitable catalysts for promoting the cross—linking include organo—tin compounds such as dibutyltin dilaurate, dibutyltin dimaleate, dibutyltin oxide, stannous octanoate and similar compounds.
  • the powder coating compositions preferably contain a flow aid, also referred to as flow control or leveling agents, to enhance the surface appearance of cured coatings of the powder coating compositions.
  • flow aids typically comprise acrylic polymers and are available from several suppliers, e.g., MODAFLOW from Monsanto Company and Acronal from BASF.
  • Other flow control agents which may be used include Modarez MFP available from Synthron, EX 486 available from Troy Chemical, BYK 360P available from BYK Mallinkrodt and Perenol F—30—P available from Henkel.
  • a specific flow aid is an acrylic polymer having a molecular weight of about 17,000 and containing 60 mole percent 2—ethylhexyl methacrylate residues and about 40 mole percent ethyl acrylate residues.
  • the amount of flow aid present may be in the range of about 0.5 to 4.0 weight percent, based on the total weight of the amorphous and semi- crystalline polyesters and the cross—linking agent.
  • the powder coating compositions may be deposited on various metallic and non-metallic substrates by known techniques for powder deposition such as by means of a powder gun, by electrostatic deposition or by deposition from a fluidized bed. In fluidized bed sintering, a preheated article is immersed into a suspension of the powder coating in air.
  • the particle size of the powder coating composition normally is in the range of 60 to
  • the powder is maintained in suspension by passing air through a porous bottom of the fluidized bed chamber.
  • the articles to be coated are preheated to about 250 to 400°F (about 121 to 205°C) and then brought into contact with the fluidized bed of the powder coating composition.
  • the contact time depends on the thickness of the coating that is to be produced and typically is from 1 to 12 seconds.
  • the temperature of the substrate being coated causes the powder to flow and thus fuse together to form a smooth, uniform, continuous, uncratered coating.
  • the temperature of the preheated article also affects cross—linking of the coating composition and results in the formation of a tough coating having a good combination of properties. Coatings having a thickness between 200 and 500 microns may be produced by this method.
  • compositions also may be applied using an electrostatic process wherein a powder coating composition having a particle size of less than
  • 100 microns preferably about 15 to 50 microns, is blown by means of compressed air into an applicator in which it is charged with a voltage of 30 to 100 kV by high- voltage direct current.
  • the charged particles then are sprayed onto the grounded article to be coated to which the particles adhere due to the electrical charge thereof.
  • the coated article is heated to melt and cure the powder particles. Coating of 40 to 120 microns thickness may be obtained.
  • Another method of applying the powder coating compositions is the electrostatic fluidized bed process which is a combination of the two methods described above. For example, annular or partially annular electrodes are mounted over a fluidized bed so as to produce an electrostatic charge such as 50 to 100 kV.
  • the article to be coated is exposed briefly to the fluidized powder.
  • the coated article then can be heated to effect cross—linking if the article was not preheated to a temperature sufficiently high to cure the coating upon contact of the coating particles with the article.
  • the powder coating compositions of this invention may be used to coat articles of various shapes and sizes constructed of heat-resistant materials such as glass, ceramic and various metal materials.
  • the compositions are especially useful for producing coatings on articles constructed of metals and metal alloys, particularly steel articles.
  • compositions and coatings of our invention are further illustrated by the following examples.
  • the inherent viscosities (I.v.; dl/g) referred to herein were measured at 25°C using 0.5 g polymer per 100 mL of a solvent consisting of 60 parts by weight phenol and 40 parts by weight tetrachloroethane.
  • Melt viscosities (poise) were determined using an ICI melt viscometer according to ASTM D4287—83. Acid and hydroxyl numbers were determined by titration and are reported herein as mg of KOH consumed for each gram of polymer.
  • Tg glass transition temperatures
  • Tm melting tempera— tures
  • Coatings were prepared on 3 inch by 9 inch panels of 24—gauge, polished, cold roll steel, the surface of which has been zinc phosphated (BONDERITE 37, The Parker Company) .
  • Impact strengths were determined using an impact tester (Gardner Laboratory, Inc.) according to ASTM D2794-84. A weight with a 5/8-inch diameter, hemispherical nose was dropped within a slide tube from a specified height to drive into the front (coated face) or back of the panel. The highest impact which did not crack the coating was recorded in inch—pounds, front and reverse.
  • the solvent resistance and the degree of cure (cross-linking) of the coatings were determined by a methyl ethyl ketone (MEK) rub procedure in which coated panels were rubbed with a two-pound ball peen hammer wrapped with cheese cloth approximately 0.5 inch thick. The cloth was wetted with MEK every 50 double strokes. The rubbing was continued until bare metal is observed or until 200 double rubs are completed. The result of each MEK rub procedure is reported as the number of double rubs required for the observation of bare metal or 200, whichever is less.
  • MEK methyl ethyl ketone
  • the flexibility of the coatings was determined in accordance with ASTM 4145—83 at ambient temperature by bending or folding a coated panel back against itself, using a hydraulic jack pressurized to 20,000 pounds per square inch (psi) , until the apex of the bend is as flat as can be reasonably achieved.
  • This bend is referred to as 0T meaning that there is nothing (zero thicknesses) between the bent portions of the panel.
  • the bend is examined using a 10X magnifying glass and a pass is recorded if no fractures of the coating are observed. If fractures of the coating are observed, the panel is bent a second time (IT) to form a three—layer sandwich. The second bend is inspected for coating fracture and this procedure is repeated, forming 4—, 5—, 6—, etc.
  • the 20 degree and 60 degree gloss are measured using a gloss meter (Gardner Laboratory, Inc. , Model GC— 9095) according to ASTM D-523.
  • the acid numbers and hydroxyl number are determined by titration and reported as mg of KOH consumed for each gram of resin.
  • the pencil hardness of a coating is that of the hardest pencil that will not cut into the coating according to ASTM 3363—74 (reapproved 1980) .
  • the results are expressed according to the following scale: (softest) 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H (hardest) .
  • the conical mandrel test is performed by bending the panel over 15 seconds using a Gardner Laboratory, Inc. , conical mandrel of specified size according to ASTM—522—85. A pass or fail is recorded.
  • the artificial weatherability of the coatings was determined by exposure of the coated panels in a Cyclic Ultraviolet Weathering Tester (QUV) with 313 nm fluorescent tubes. The test condition was 8 hours of light at 70°C and 4 hours of condensation at 45° C.
  • QUV Cyclic Ultraviolet Weathering Tester
  • This example illustrates the typical procedure for preparing the aliphatic polyesters of the invention.
  • the flask and contents are heated under nitrogen atmosphere to a temperature of 170°C at which point methanol begins to distill rapidly from the flask.
  • the reaction mixture is heated with stirring at this temperature for about 1 hour, the temperature is increased to 200°C. for 2 hours, raised to 215°C. for 4 hours, and then to 235°C.
  • a vacuum of 10 mm of mercury is applied over a period of 18 minutes. Stirring is continued under 10 mm of mercury at 235°C. for about 3 hours to produce a low melt viscosity, colorless polymer.
  • the polymer has an inherent viscosity of 0.30, a melting point of 130°C, and a hydroxyl number of 30.
  • a powder coating composition is prepared from the following materials:
  • the above materials were melt—blended in an APV twin screw extruder at 110°C, ground in a Bantam mill to which a stream of liquid nitrogen was fed and classified through a 170 mesh screen on a KEK centrifugal sifter.
  • the finely—divided powder coating composition thus obtained had an average particle size of about 50 microns.
  • the powder coating composition prepared in Example 2 was applied electrostatically to one side of the 3 inch by 9 inch panels described above.
  • the coating was cured (i.e., cross-linked) by heating the coated panels at 177°C. in an oven for 20 minutes.
  • the cured coatings are generally about 50 microns thick.
  • the coatings on the panel have both front and back impact strengths of >160 inch—pounds, 20° and 60° gloss values of 84 and 94, respectively, and a pencil hardness of F.
  • the coated panels pass a 0.125 inch conical mandrel test and have a T—bend flexibility value of 1. After 520 hours of QUV exposure, the coating retains 50% of the 60° gloss.
  • Example 2 Using the procedure described in Example 2, a powder coating composition was prepared from the following materials:
  • Example 2 panels were coated with this powder coating composition and the coatings were cured and evaluated.
  • the coatings have both front and back impact strengths of >160 inch—pounds and 20° and 60° gloss values of 82 and 94, respectively, and a pencil hardness of F.
  • the coated panels pass a 0.125 inch conical mandrel and have a T—bend flexibility value of 0. After 500 hours of QUV exposure, the coating retains 50% of the 60° gloss.
  • This example illustrates the typical procedure for preparing the aliphatic polyesters of this invention using 1,4—cyclohexanedicarboxylic acid.
  • a 3000 mL, 3— necked, round—bottom flask equipped with a stirrer, a short distillation column, and an inlet for nitrogen was charged with 1,4—cyclohexanedicarboxylic acid (1100.3 g, 6.39 mol), 1,4-butanediol (629.77 g, 6.68 mol), 1.5 g of butanestannoic acid (FASCAT 4100) catalyst.
  • the flask and contents are heated under nitrogen atmosphere at
  • the temperature was then increased to 215° C for 2 hours and then to 235° C for 8 hours to produce a low melt viscosity, colorless polymer.
  • the polymer has an inherent viscosity of 0.25, a melting point of 155° C, and a hydroxyl number of 36.
  • Example 2 183.4 g Self—blocked isophorone diisocyanate (Huls BF 1540) ; 10.0 g Dibutyltin dilaurate; 10.0 g Benzoin; 15.0 g MODAFLOW III; 400.0 g Ti0 2 ; 10.0 g TINUVIN 144; and 10.0 g TINUVIN 234.
  • Huls BF 1540 Self—blocked isophorone diisocyanate
  • Dibutyltin dilaurate 10.0 g Benzoin
  • 15.0 g MODAFLOW III 400.0 g Ti0 2 ; 10.0 g TINUVIN 144; and 10.0 g TINUVIN 234.
  • Example 2 panels were coated with this powder coating composition and the coatings were cured and evaluated.
  • the coatings have both front and back impact strengths of >160 inch—pounds and 20° and 60° gloss values of 84 and 96, respectively, and a pencil hardness of F.
  • the coated panels pass a 0.125 inch conical mandrel and have a T—bend flexibility value of 0. After 600 hours of QUV exposure, the coating retains 50% of the 20° gloss.
  • a powder coating composition was prepared from the following materials:
  • Example 2 232.0 g Self-blocked isophorone diisocyanate (Huls BF 1540) ; 12.0 g Dibutyltin dilaurate;
  • Example 2 Using the procedure of Example 2, panels were coated with this powder coating composition and the coatings were cured at 177°C for 20 minutes and evaluated. Coated panels have front impact of 60 inch- pounds and back impact of 10-inch pounds. The 20° and 60° gloss values were 86 and 96, respectively, and the pencil hardness is F. The coated panels fail a 0.125 inch conical mandrel test and have a T—bend flexibility value of 6. After 220 hours of QUV weathering exposure, the coating retains 50% of the 60° gloss.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Paints Or Removers (AREA)

Abstract

Sont décrites des compositions pulvérulentes pour revêtements thermodurcissables constituées d'un polyester aliphatique, d'un polyester aromatique eet d'un polyisocyanate auto-bloqué. Sont également décrits des articles façonnés ou moulés revêtus de ces compositions et durcis.
EP92919099A 1991-08-27 1992-08-26 Compositions pulverulentes pour revetements thermodurcissables Ceased EP0601079A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US750342 1985-06-28
US75034291A 1991-08-27 1991-08-27
PCT/US1992/007083 WO1993004102A1 (fr) 1991-08-27 1992-08-26 Compositions pulverulentes pour revetements thermodurcissables

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EP0601079A1 true EP0601079A1 (fr) 1994-06-15

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JP (1) JPH07501353A (fr)
KR (1) KR940702520A (fr)
CA (1) CA2115763A1 (fr)
WO (1) WO1993004102A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012122098A1 (fr) 2011-03-06 2012-09-13 King Industries, Inc. Compositions d'un complexe métal amidine et d'un second composé, compositions de revêtement les comprenant
EP3763762A1 (fr) 2019-07-11 2021-01-13 Covestro Intellectual Property GmbH & Co. KG Peinture pulvérulente de polyuretdione
WO2021004980A1 (fr) 2019-07-11 2021-01-14 Covestro Intellectual Property Gmbh & Co. Kg Procédé de fabrication de composés contenant des groupes allophanate et/ou thioallophanate
EP3872108A1 (fr) 2020-02-28 2021-09-01 Covestro Intellectual Property GmbH & Co. KG Compositions contenant des groupes uretdione
EP3916032A1 (fr) 2020-05-29 2021-12-01 Covestro Deutschland AG Compositions à réticulation à basses températures contenant des groupes urétdione
EP4029892A1 (fr) 2021-01-13 2022-07-20 Covestro Deutschland AG Compositions contenant des groupes urétdione

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US5405920A (en) * 1994-08-08 1995-04-11 Eastman Chemical Company Polyurethane powder coatings
EP0745628B1 (fr) * 1995-05-31 2002-04-03 Shell Internationale Researchmaatschappij B.V. Composition de copolyester
DE19616496A1 (de) * 1996-04-25 1997-10-30 Bayer Ag Abspaltfreier Polyurethan-Pulverlack mit niedriger Einbrenntemperatur
ATE301168T1 (de) * 2000-05-23 2005-08-15 Akzo Nobel Coatings Int Bv Herstellung eines dekorierten substrats unter verwendung einer thermisch vernetzbaren beschichtungszusammensetzung
DE102004017005A1 (de) 2004-04-02 2005-10-20 Bayer Materialscience Ag Abspalterfreier Polyurethan-Pulverlack mit niedriger Einbrenntemperatur
MY139524A (en) * 2004-06-30 2009-10-30 Ciba Holding Inc Stabilization of polyether polyol, polyester polyol or polyurethane compositions
US7485729B2 (en) 2004-08-12 2009-02-03 King Industries, Inc. Organometallic compositions and coating compositions
DE102006045003A1 (de) 2006-09-23 2008-03-27 Bayer Materialscience Ag Polyurethan-Pulverlack
JP5326207B2 (ja) * 2006-12-15 2013-10-30 東洋紡株式会社 コーティング組成物、積層体及びフレキシブルフラットケーブル

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US4352924A (en) * 1981-06-29 1982-10-05 Eastman Kodak Company Thermosetting powder coating compositions
US4859760A (en) * 1987-12-07 1989-08-22 Eastman Kodak Company Polyurethane powder coating compositions
WO1991007452A1 (fr) * 1989-11-20 1991-05-30 Eastman Kodak Company Compositions de revetement par poudre

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Title
See references of WO9304102A1 *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2012122098A1 (fr) 2011-03-06 2012-09-13 King Industries, Inc. Compositions d'un complexe métal amidine et d'un second composé, compositions de revêtement les comprenant
EP3763762A1 (fr) 2019-07-11 2021-01-13 Covestro Intellectual Property GmbH & Co. KG Peinture pulvérulente de polyuretdione
WO2021004980A1 (fr) 2019-07-11 2021-01-14 Covestro Intellectual Property Gmbh & Co. Kg Procédé de fabrication de composés contenant des groupes allophanate et/ou thioallophanate
EP3872108A1 (fr) 2020-02-28 2021-09-01 Covestro Intellectual Property GmbH & Co. KG Compositions contenant des groupes uretdione
EP3916032A1 (fr) 2020-05-29 2021-12-01 Covestro Deutschland AG Compositions à réticulation à basses températures contenant des groupes urétdione
WO2021239678A1 (fr) 2020-05-29 2021-12-02 Covestro Deutschland Ag Compositions contenant des groupes uretdione se réticulant à basses températures
EP4029892A1 (fr) 2021-01-13 2022-07-20 Covestro Deutschland AG Compositions contenant des groupes urétdione
WO2022152536A1 (fr) 2021-01-13 2022-07-21 Covestro Deutschland Ag Compositions comprenant des urétdiones

Also Published As

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CA2115763A1 (fr) 1993-03-04
KR940702520A (ko) 1994-08-20
JPH07501353A (ja) 1995-02-09
WO1993004102A1 (fr) 1993-03-04

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