Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
  • C09D175/04—Polyurethanes
  • C09D175/06—Polyurethanes from polyesters
• • 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
• • 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
  • C08G18/791—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates containing isocyanurate groups
  • C08G18/792—Nitrogen characterised by the polyisocyanates used, these having groups formed by oligomerisation of isocyanates or isothiocyanates containing isocyanurate groups formed by oligomerisation of aliphatic and/or cycloaliphatic isocyanates or isothiocyanates
• • 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
  • C08G18/8061—Masked polyisocyanates masked with compounds having only one group containing active hydrogen
  • C08G18/8093—Compounds containing active methylene groups

Definitions

• the present invention relates to new blocked polyisocyanates, a process for their preparation and their use in polyurethane systems.
• Polyurethane paints preferably one-component (1-component) polyurethane systems.
• One-component (IC) polyurethane systems are widely used in the field of industrial stoving enamels, such as car series painting and coil coating, and are characterized by very good film properties, such as chemical resistance, scratch resistance and weathering stability.
• the coating films are cured by thermal activation (baking process) of the blocked polyisocyanates with polyols, if appropriate in the presence of a suitable catalyst.
• thermal activation baking process
• suitable blocking agents in principle can be found e.g. in Wicks et al. in Progress in Organic Coatings 1975, 3, pp. 73-79, 1981, 9, pp. 3-28 and 1999, 36, pp. 148-172.
• the blocked polyisocyanates must be capable of being crosslinked at a stoving temperature of maximum 140 ° C. and have only a very slight, preferably no, thermal yellowing during the stoving process.
• the baking temperature is mainly determined by the reactivity of the blocked polyisocyanates
• the majority of the stoving systems such as melamine / formaldehyde and urea-formaldehyde resins, are characterized by the fact that volatile constituents are released during curing, which increase the VOC value.
• isocyanate-blocked isocyanates are now predominantly used (e.g. EP-A 0947 531).
• blockages with e.g. N-heterocyclic compounds, such as caprolactam or butanone oxime do not completely cleave the blocking agent here; rather, this blocking agent transesterifies the isocyanate blocked with diethyl malonate. During this transesterification, ethanol is split off.
• This process can be carried out at relatively low stoving temperatures because the second, adjacent ester function is an activated ester.
• the disadvantage of this method is that such systems are extremely susceptible to the action of acids, since the unstable ester bond can be split quickly. That’s why
• the object of the present invention was to provide new blocked polyisocyanate systems which can be used without elimination of the blocking agent, i.e. react emission-free and have low networking temperatures.
• these blocked polyisocyanate systems should be stable in storage at ambient temperature and, in particular, should also be suitable in combination with suitable polyol components for the production of one-component stoving enamels.
• CH-acidic compounds with the basic structure of an activated cyclic Ketones especially of the cyclopentanone-2-carboxymethyl ester, are particularly well suited to obtaining cleavage-free coatings with a low tendency to yellowing.
• the invention relates to organic polyisocyanates with at least two isocyanate groups, the isocyanate group of which with CH-acidic cyclic ketones of the general formula (I),
• X is an electron-withdrawing group
• R l and R 2 independently of one another are the radicals H, C 1 -C 2 o- (cyclo) alkyl, C 6 -C 24 aryl, C 1 -C 20 - (cyclo) alkyl ester or amide, C 6 -C 4 - Aryl ester or amide, mixed aliphatic / aromatic radicals having 1 to 24 carbon atoms, which can also be part of a 4 to 8-membered ring,
• n is an integer from 0 to 5
• blocked isocyanate groups (calculated as NCO) of in total 0.1 to 20% by weight.
• a blocked isocyanate group content (calculated as NCO) of 0.1 to 15.6% by weight is preferred.
• a blocked isocyanate group content (calculated as NCO) of 0.1 to 14% by weight is particularly preferred.
• the electron-withdrawing group X can be any substituent which leads to a CH acidity of the ⁇ -hydrogen.
• substituents can be, for example, ester groups, amide groups, sulfoxide groups, sulfone groups, nitro groups, phosphonate groups, nitrile groups, isonitrile groups, polyhaloalkyl groups, halogens such as fluorine, chlorine or carbonyl groups.
• Nitrile and ester groups are preferred, and carboxylic acid methyl ester and carboxylic acid ethyl ester groups are particularly preferred.
• the activated cyclic ketone of the formula (I) preferably has a ring size of 5
• Preferred compounds of the general formula (I) are cyclopentanone-2-carboxymethyl ester and -carboxyethyl ester, cyclopentanone-2-carboxylic acid nitrile, cyclo-hexanone-2-carboxymethyl ester and -carboxyethyl ester or cyclopentanone-2-carbonyl methyl.
• Cyclopentanone-2-carboxymethyl ester and carboxyethyl ester and cyclohexanone-2-carboxymethyl ester and carboxyethyl ester are particularly preferred.
• the cyclopentanone systems are technically easily obtainable by a Dieckmann condensation of dimethyl adipate or diethyl adipate.
• Cyclohexanone-2-carboxymethyl ester can be prepared by hydrogenation of methyl saucylate.
• the polyisocyanate to be blocked can be any organic polyisocyanate which is suitable for crosslinking compounds with active hydrogen, ie aliphatic including the cycloaliphatic, aromatic and heterocyclic polyisocyanates with at least two isocyanate groups and mixtures thereof.
• polyisocyanates are aliphatic isocyanates such as di- or triisocyanates, for example butane diisocyanate (BDI), pentane diisocyanate, hexane diisocyanate (HDI), 4-isocyanatomethyl-l, 8-octane diisocyanate (triisocyanatononane, TIN) or cyclic systems such as 4,4 '-Methylene-bis (cyclohexyl isocyanate) (Desmodur ® W, Bayer AG, Leverkusen), 3,5,5-trimethyl-l-isocyanato-3-isocyanatomethylcyclohexane (IPDI) and ⁇ , ⁇ '-diisocyanato-1,3 -dimethylcyclohexane (H 6 XDI).
• BDI butane diisocyanate
• HDI hexane diisocyanate
• TIN 4-isocyanatomethyl
• aromatic polyisocyanates examples include 1,5-naphthalene diisocyanate, diisocyanato-diphenylmethane (MDI) or crude MDI, diisocyanatomethylbenzene (TDI), in particular the 2,4 and 2,6-isomers and technical mixtures of the two isomers, and 1,3 -Bis (isocyanato-methyl) benzene (XDI).
• MDI diisocyanato-diphenylmethane
• TDI diisocyanatomethylbenzene
• XDI 1,3 -Bis (isocyanato-methyl) benzene
• polyisocyanates which are obtainable by reacting the di- or triisocyanates with themselves via isocyanate groups, such as uretdiones or carbodiimide compounds or such as isocyanurates or hninooxadiazinediones, which are formed by the reaction of three isocyanate groups.
• the polyisocyanates can also contain monomeric di- and / or triisocyanates and / or oligomeric polyisocyanates with biuret, AUophanat- and acylurea structural elements, low-monomer or proportionally modified monomeric di-, triisocyanates and any mixtures of the polyisocyanates mentioned.
• Polyisocyanate prepolymers which have on average more than one isocyanate group per molecule are also very suitable. They are obtained by pre-reacting a molar excess, for example one of the above-mentioned polyisocyanates, with an organic material which has at least two active hydrogen atoms per molecule, e.g. in the form of hydroxy groups.
• Preferred polyisocyanates are those which contain a uretdione, isocyanurate, iminooxadiazinedione, acylurea, biuret or allophanate structure, for example those based on butane diisocyanate (BDI), pentane diisocyanate, hexane diisocyanate (HDI), 4-isocyanatomethyl-l , 8-octane diisocyanate (triisocyanatononane, TIN) or cyclic systems such as 4,4'-methylene-bis (cyclohexyl isocyanate) (Desmodur W, Bayer AG, Leverkusen), 3,5,5-trimethyl-l-isocyanato-3-isocyanatomethylcyclohexane (IPDI) and ⁇ , ⁇ '-diisocyanato-l, 3-dimethylcyclohexane (H 6 XDI).
• BDI butane
• aromatic polyisocyanates examples include 1,5-naphthalene diisocyanate, diisocyanato-diphenylmethane (MDI) or crude MDI, dusocyanatomethylbenzene (TDI), in particular the 2,4 and the 2,6-isomers and technical mixtures of the two isomers as well 1,3-bis (isocyanato-methyl) benzene (XDI).
• MDI diisocyanato-diphenylmethane
• TDI dusocyanatomethylbenzene
• XDI 1,3-bis (isocyanato-methyl) benzene
• Particularly preferred polyisocyanates are those based on hexane diisocyanate (HDI), 4,4'-methylene-bis (cyclohexyl isocyanate) and on 3,5,5-trimethyl-l-isocyanato-3-isocyanatomethylcyclohexane (IPDI).
• HDI hexane diisocyanate
• IPDI 3,5,5-trimethyl-l-isocyanato-3-isocyanatomethylcyclohexane
• Another object of the present invention is a process for the preparation of the blocked organic polyisocyanates according to the invention, characterized in that polyisocyanates with CH-acidic cyclic ketones of the general formula (I)
• X is an electron-withdrawing group
• R 1 and R 2 independently of one another are the radicals H, CrC 20 - (cyclo) alkyl, C 6 -C 4 - aryl, C 1 -C 20 - (cyclo) alkyl ester or amide, C 6 -C 24 aryl ester or - amide, mixed aliphatic / aromatic radicals with 1 to 24 carbon atoms, which can also be part of a 4 to 8-membered ring, n is an integer from 0 to 5,
• An isocyanate group equivalent of the polyisocyanate component to be blocked is preferably reacted with 1 equivalent of blocking agent.
• Alkali and alkaline earth metal bases such as e.g. powdered sodium carbonate (soda) suitable.
• sodium carbonate e.g. powdered sodium carbonate (soda) suitable.
• trisodium phosphate or Dabco (1,4-diazabicyclo [2.2.2] octane) can also be used.
• the carbonates of the metals of the second subgroup are also suitable. Sodium carbonate or potassium carbonate is preferably used.
• the reaction of the cyclic ketone with the isocyanate can also be carried out in the presence of
• Zinc salts can be carried out as catalysts.
• the reaction with zinc 2-ethylhexanoate is particularly preferred. Mixtures of catalysts can also be used.
• the reaction can be carried out at room temperature or at higher temperatures up to 140 ° C.
• a temperature range from 40 to 90 ° C. is preferred, particularly preferably 15 ° C. to 90 ° C.
• Suitable solvents are the usual paint solvents, e.g. Butyl acetate, methoxyproacetate or solvent naphtha from Exxon-Chemie (Esso).
• the blocking is preferably carried out in the solvents mentioned, the solids content to be set being between 10 and 90%.
• mixtures of any blocking agents can also be used in the process according to the invention in order to achieve the desired coating properties, the proportion of compounds of the formula (I) being at least 30% by weight , preferably 50% by weight, particularly preferably 100% by weight.
• the invention also relates to a process for the production of 1-component PU stoving enamels, characterized in that organic polyisocyanates according to the invention are used as crosslinking components for organic polyhydroxyl compounds.
• the blocked polyisocyanates according to the invention are notable for the fact that, in combination with a suitable organic polyhydroxyl compound and in the presence of suitable catalysts, they are baked in for 15 to 30 minutes and at temperatures of 110 to 140 ° C., preferably 120 to 140 ° C. Harden. The stoving times depend in particular on the amount of the catalyst used. It is preferably baked at a temperature of 120-140 ° C. over a period of 30 minutes.
• Coatings are used, these are cured with a baking time of a maximum of two minutes, preferably within 5 to a maximum of 35 seconds.
• the oven temperature is 300-400 ° C.
• the stoving conditions naturally depend on the material used and the sheet thickness of the sheet metal strip to be coated.
• the oven temperature is usually at a minimum temperature of 180 ° C and a maximum of 260 ° C PMT.
• a temperature range from 210 ° C. to 245 ° C. is preferred PMT.
• a range from 216 ° C. to 241 ° C. PMT is particularly preferred.
• the paint properties of the baked paint film such as MEK (methyl ethyl ketone) solvent resistance, hardness and elasticity at a given baking temperature, depend, among other things, on the amount of catalyst used. It is preferably baked at a temperature of 232 ° C. over a period of 38 seconds. Temperatures of 216 ° C are also possible. With the substrate aluminum, a burn-in time of 33 seconds results. The optimum specific conditions are determined in a manner customary for the person skilled in the art by means of preliminary preliminary tests, and in use the temperatures in the coil coating furnace are checked by means of a sensitive band.
• MEK methyl ethyl ketone
• Suitable catalysts for the crosslinking are, for example, DBTL (dibutyltin dilaurate), titanium 2-ethylhexanoate, titanium tetraisopropylate and other common titanium (IV) compounds, zirconium 2-ethylhexanoate and other common zirconium (TV) compounds, Aluminum triethylate, scandium trifluoromethanesulfonate, yttrium
• Suitable polyhydroxyl compounds for this purpose as well as further details regarding the manufacture and use of such stoving enamels can be found in the literature, for example DE-A 19 738 497 or EP-A 0 159 117.
• Particularly preferred areas of application for the products according to the invention are theirs Use as a crosslinker in automotive fillers, and use as a crosslinker in the coil coating sector.
• blocked polyisocyanates according to the invention can be cured with di- or polyamines. This reaction is preferably carried out at room temperature. It can be used to produce lacquer coatings or workpieces.
• Polyester polyols, polycarbonate polyols and polyacrylate polyols can be used to produce coil coatings. In principle, all binders with a sufficiently high OH content can be used.
• the binders according to the invention can also contain other stabilizing additives, such as. B. HALS amines or solvents and up to 5 wt .-% of an OH-functional hydrazide compound (based on the solids of the finished paint).
• Other additives include, for example, CAB (cellulose acetobutyrate) and, for example, Acronal ® 4 F (leveling agent and defoamer)
• polyisocyanate used is a polyisocyanate having an isocyanurate-HDI, isocyanate content 21.8%, viscosity 3200 mPa-s, (Desmodur ® N3300, Bayer AG, Leverkusen).
• the blocking agents used, cyclopentanone-2-carboxymethyl ester and cyclohexanone-2-carboxymethyl ester were obtained from Fluka and used without further purification.
• polyisocyanates listed in the table below are processed in a stoichiometric manner with polyols according to the recipes listed below to give clear coats with the addition of the common additives Baysilone ® OL 17 (Bayer AG,
• Desmophen ® A 870 polyacrylate polyol
• Tinuvin ® 292 (Ciba AG, Basel, Switzerland), 10% in xylene 4.78 Tinuvin ® 1130 (Ciba AG, Basel, Switzerland), 10% in xylene 9.56
• Catalyst content 1.5% (solid on solid binder).
• the system shows very little yellowing. This system can also be used successfully if the NCO / OH ratio is 1: 1.5.
• Tinuvin ® 292 (Ciba AG, Basel, Switzerland), 10% in xylene 4.80
• Tinuvin ® 1130 (Ciba AG, Basel, Switzerland), 10% in xylene 9.61
• Baking condition 30 minutes at 140 ° C.
• Baking temperatures a clear yellowing.
• the Delta-b value of 140 to 160 ° C (30 minutes) is 3.2 and is therefore about four times as high; compared to a system that has a low yellowing (eg dimethylpyrazole), based on an application on a white solvent-based basecoat.
• Color system (DIN 6174, "Colorimetric determination of color differences in body colors according to the CIELAB formula” (edition 01.79). This value should be as close as possible to 0 for non-yellowing clear coats.
• the blocked theoretical NCO content is 8.3%.
• the desired viscosity is then set with 7% 2-butanol based on solids. 2.5% of solids (8.7 g) of Tinuvin ® 770 DF are also added.
• the polyisocyanate used is a polyisocyanate having an isocyanurate-HDI, isocyanate content 21.8%, viscosity 3000 mPas, (Desmodur ® N 3300, Bayer AG, Leverkusen).
• the polyisocyanate used is a mixture of an HDI polyisocyanate with an isocyanurate structure, NCO content 21.8%, viscosity 3000 mPas (Desmodur ® N3300, Bayer AG, Leverkusen) and a polyisocyanate with an isocyanurate structure based on IPDI ( NCO content 11.9%, viscosity 2000 mPas, Desmodur ® Z4470, Bayer AG, Leverkusen),.
• Tinuvin 770 DF added.
• the polyisocyanate used is a mixture of an HDI polyisocyanate with an isocyanurate structure, NCO content 21.8%, viscosity 3000 mPas (Desmodur ® N3300, Bayer AG, Leverkusen) and a polyisocyanate with an isocyanurate structure based on Desmodur W. (13.5% Desmodur ® N3300, degree of trimerization 20%,
• IK-PUR-Coil Coating top coats white, polyol component Alkynol ® 1665
• A polyisocyanate A
• B polyisocyanate B
• C polyisocyanate C
• Solids content (% by weight) approx. 60
• CAB Cellulose Acetobutyrate Supplier: Krahn Chemie Hamburg, Manufacturer: Eastman Kingsport USA; CAB 531-1 (approx. 53% butyryl content, hydroxyl content 1.7% - is not calculated)
• the MEK wipe test is a quick test to check the final hardening of the paint film. To do this, a cotton ball soaked in MEK is moved back and forth with a constant pressure on the paint film.
• Device / auxiliary scale (brand Bizerba), weight stones 100 g, 1 kg and 2 kg
• the device with which this method can be carried out consists of a
• the samples are stored for at least 24 hours at laboratory room temperature and humidity. The measurements are carried out under the same conditions.
• the bending edge is examined for cracks with a 20 x magnifying glass.
• the adhesion is then checked by pressing three times and tearing off an adhesive tape.
• This 0 T bend is checked with R for cracks and H for adhesion with a rating of 0-5, where 0 is the best value and 5 is the worst value.
• the test is ended at 3.0 T at the latest.
• the deformed T-bend strip is heated to 100 ° C for 30 min and then checked again for cracks. Paint production:
• the test was carried out in the white coil coating topcoat according to a standard recipe (guideline recipe RR 6830).
• a mill base was first prepared with the oil-free saturated polyester according to the following pearl mill formulation:
• the millbase was dispersed with 2 mm silica quartz beads.
• the ground material is separated from the glass beads by sieving.
• PIC in this case Desmodur ® BL 3175 as a comparison.
• Polyol and blocked poly Lyisocyanate are combined in an equivalent way, ie if fewer blocked NCO groups are available, the proportion of blocked PIC must be increased.
• the equivalent weights are given in the leaflet.
• the varnish is adjusted to the processing viscosity of approx. 70 sec DEN 4/23 ° C by Solvesso ® 200 S.
• the coating was applied to chromated aluminum sheets (1mm thick) by knife coating.
• the sheets were baked in the Aalborg oven on the turntable.
• the dry layer thickness is 20 - 22 ⁇ m.
• Binder Alkynol 1665 Catalyst: 0.2% (calculated on binder) Bdm. Ratio: equivalent baking conditions: 232 ° C (PMT) pigments Titanium dioxide Kronos 2330 dumbbell: 42 binder-pigment ratio: 1: 1 substrate: Al sheet pretreated with Bonder 722

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• Organic Chemistry (AREA)
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• Chemical Kinetics & Catalysis (AREA)
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• Polymers & Plastics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Wood Science & Technology (AREA)
• Polyurethanes Or Polyureas (AREA)
• Paints Or Removers (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 2002
  • 2002-07-03 PL PL02367450A patent/PL367450A1/xx not_active Application Discontinuation
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