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EP-4296325-B1 - COATING COMPOSITION, FOR METAL, WITH IMPROVED OIL RESISTANCE AND ADHESIVENESS AND A PREPARATION METHOD THEREFOR, AND A METAL ARTICLE COATED WITH COMPOSITION

EP4296325B1EP 4296325 B1EP4296325 B1EP 4296325B1EP-4296325-B1

Inventors

  • LEE, JAE HOON
  • IM, JUN SEOP

Dates

Publication Date
20260513
Application Date
20220216

Claims (13)

  1. A coating composition for metal comprising, based on total 100 parts by weight of the composition, 5.1 to 64.9 parts by weight of (meth)acryl-modified polyurethane; 7.1 to 74.9 parts by weight of (meth)acrylic monomer; 2.1 to 44.9 parts by weight of epoxy resin; 0.051 to 2.49 parts by weight of epoxy curing promotor; and 0.00051 to 2.49 parts by weight of thermal polymerization initiator, wherein the (meth)acryl-modified polyurethane comprises i) polymerized units derived from anhydrosugar alcohol-alkylene oxide adduct; ii) polymerized units derived from polyisocyanate; and iii) polymerized units derived from hydroxyalkyl (meth)acrylate.
  2. The coating composition for metal of claim 1, wherein the anhydrosugar alcohol-alkylene oxide adduct is an adduct obtained by reacting hydroxyl group(s) at both ends or one end of anhydrosugar alcohol with alkylene oxide, and wherein the alkylene oxide is a linear alkylene oxide having 2 to 8 carbons or a branched alkylene oxide having 3 to 8 carbons.
  3. The coating composition for metal of claim 2, wherein the anhydrosugar alcohol is isosorbide, isomannide, isoidide or a mixture thereof.
  4. The coating composition for metal of claim 1, wherein the polyisocyanate is methylenediphenyl diisocyanate (MDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), or a combination thereof.
  5. The coating composition for metal of claim 1, wherein the hydroxyalkyl (meth)acrylate is hydroxy-C 1-8 alkyl (meth)acrylate.
  6. The coating composition for metal of claim 1, wherein the (meth)acryl-modified polyurethane is represented by the following formula 2: in the above formula 2, each of R1 is independently an alkylene group, each of R2 is independently an alkylene group, a cycloalkylene group, or an arylene group, each of R3 is independently an alkylene group, each of R4 is independently a hydrogen atom or an alkyl group, M is a divalent organic group derived from anhydrosugar alcohol, each of m and n independently represents an integer of 0 to 15, and m+n represents an integer of 1 to 30.
  7. The coating composition for metal of claim 1, wherein the (meth)acryl-modified polyurethane is that prepared by a method comprising the steps of: reacting anhydrosugar alcohol-alkylene oxide adduct and polyisocyanate to prepare intermediate having terminal isocyanate group; and reacting the intermediate and hydroxyalkyl (meth)acrylate.
  8. The coating composition for metal of claim 1, wherein the (meth)acrylic monomer is a monomer having 1 to 4 (meth)acrylic groups in the molecule.
  9. The coating composition for metal of claim 1, wherein the epoxy resin is a resin having 2 or more epoxy groups in the molecule.
  10. The coating composition for metal of claim 1, wherein the thermal polymerization initiator is selected from compounds represented by the following formula 3-1, compounds represented by the following formula 3-2, or mixtures thereof: in the above formula 3-1, each of R and R' is independently C2-C8 linear or C3-C8 branched alkyl group; C3-C20 cycloalkyl group; C6-C20 aryl group; or a C2-C8 linear or C3-C8 branched methoxy-alkyl group, X is -CN or -CO 2 R", where R" is C2-C8 linear or C3-C8 branched alkyl group; C3-C20 cycloalkyl group; or C6-C20 aryl group, in the above formula 3-2, each of R is independently C2-C8 linear or C3-C8 branched alkyl group; C3-C20 cycloalkyl group; or C6-C20 aryl group.
  11. A method for preparing a coating composition for metal, comprising the step of mixing, based on total 100 parts by weight of the mixture, 5.1 to 64.9 parts by weight of (meth)acryl-modified polyurethane; 7.1 to 74.9 parts by weight of (meth)acrylic monomer; 2.1 to 44.9 parts by weight of epoxy resin; 0.051 to 2.49 parts by weight of epoxy curing promotor; and 0.00051 to 2.49 parts by weight of thermal polymerization initiator, wherein the (meth)acryl-modified polyurethane comprises i) polymerized units derived from anhydrosugar alcohol-alkylene oxide adduct; ii) polymerized units derived from polyisocyanate; and iii) polymerized units derived from hydroxyalkyl (meth)acrylate.
  12. The method for preparing a coating composition for metal of claim 11, wherein the mixing of the (meth)acryl-modified polyurethane, (meth)acrylic monomer, epoxy resin, epoxy curing promotor and thermal polymerization initiator is conducted under temperature condition of 60°C or lower.
  13. A coated metallic article comprising: a metallic article; and a coating layer of the coating composition for metal of any one of Claims 1 to 10 on the surface of the metallic article.

Description

TECHNICAL FIELD The present invention relates to a coating composition for metal with improved oil resistance and adhesion and a method for preparing the same, and a metallic article coated with the composition, and more specifically, the present invention relates to a coating composition which comprises (meth)acryl-modified polyurethane comprising polymerized units derived from anhydrosugar alcohol-alkylene oxide adduct, (meth)acrylic monomer, and epoxy resin, and can provide a coating with excellent adhesion to metal and improved oil resistance at the same time, and a method for preparing the same, and a metallic article coated with the composition. BACKGROUND ART Polyols and isocyanates, which are essential components for polyurethane, are usually prepared from petroleum-based raw materials. However, in the field of polyurethane, due to various reasons such as accelerated depletion of petroleum resources, demand to reduce greenhouse gas emissions according to climate change, rise of raw material prices, and increasing need for recyclable raw materials, a method for partially or completely replacing polyols and isocyanates prepared from petroleum-based raw materials with environmentally friendly components has been requested. Polyols can be produced from recyclable biomass such as natural vegetable oils, cellulose, lignin, etc., and biopolyols derived from natural vegetable oils are already being produced on a commercial scale. The properties of biopolyol produced become different according to the type of biomass used for the production. In general, castor oil, palm oil, etc. are used for the production of soft and hard polyurethanes and synthetic polyols, and soybean oil is used for the production of polyols for soft polyurethane. However, the currently produced biomass-based biopolyol has a disadvantage in that it has a high viscosity. Natural vegetable oil-based isocyanates are essentially aliphatic compounds, which have a disadvantage in that they are less reactive than aromatic diisocyanates which are based on petroleum. Therefore, research on preparing diisocyanate using biomass has not been conducted much. Hydrogenated sugar (also referred to as "sugar alcohol") means a compound obtained by adding hydrogen to the reductive end group in sugar, and generally has a chemical formula of HOCH2(CHOH)nCH2OH wherein n is an integer of 2 to 5. According to the number of carbon atoms, hydrogenated sugar is classified into tetritol, pentitol, hexitol and heptitol (4, 5, 6 and 7 carbon atoms, respectively). Among them, hexitol having 6 carbon atoms includes sorbitol, mannitol, iditol, galactitol, etc. and in particular, sorbitol and mannitol are very useful materials. Anhydrosugar alcohol is a material formed by removing one or more molecules of water from inside of the hydrogenated sugar. It has a tetraol form with four hydroxyl groups in the molecule when one molecule of water is removed, and a diol form with two hydroxyl groups in the molecule when two molecules of water are removed, and can be produced by using hexitol derived from starch (for example, Korean Patent No. 10-1079518 and Korean Laid-open Patent Publication No. 10-2012-0066904). Because anhydrosugar alcohol is an environmentally friendly material derived from recyclable natural resources, it has received much interest for a long time and researches on its production continue to proceed. Among such anhydrosugar alcohols, isosorbide produced from sorbitol has the widest industrial applicability at present. Anhydrosugar alcohol can be used in various fields including treatment of heart and blood vessel diseases, patch adhesive, medicaments such as mouthwash, etc., solvents for compositions in the cosmetics industry, emulsifiers in the food industry, etc. In addition, it can increase the glass transition temperature of polymer materials like polyester, PET, polycarbonate, polyurethane, epoxy resin, etc., and improve the strength of such materials. Furthermore, because anhydrosugar alcohol is an environmentally friendly material derived from natural resources, it is very useful in the plastics industry such as bioplastics and the like. It is also known that anhydrosugar alcohol can be used as an adhesive, environmentally friendly plasticizer, biodegradable polymer, and environmentally friendly solvent for water-soluble lacquer. As such, anhydrosugar alcohol is receiving much interest because of its wide applicability, and the level of practical industrial application thereof is increasing. Coating compositions comprising urethane acrylates derived from anhydrosugar alcohols are for instance described in EP 2 990 428 A1. Korean Laid-open Patent Publication No. 10-2017-0125328 discloses preparation of an electroconductive adhesive for metal-metal interface from acryl-modified polyurethane and other acrylic monomers in the presence of thermal polymerization initiator. However, an adhesive composition prepared as such has insufficient oil resistance and