CA2169226A1 - Blocked polyisocyanates, process for their preparation, and coating materials and coating systems produced therefrom - Google Patents
Blocked polyisocyanates, process for their preparation, and coating materials and coating systems produced therefromInfo
- Publication number
- CA2169226A1 CA2169226A1 CA002169226A CA2169226A CA2169226A1 CA 2169226 A1 CA2169226 A1 CA 2169226A1 CA 002169226 A CA002169226 A CA 002169226A CA 2169226 A CA2169226 A CA 2169226A CA 2169226 A1 CA2169226 A1 CA 2169226A1
- Authority
- CA
- Canada
- Prior art keywords
- blocked
- polyisocyanate
- hydrogen
- blocked polyisocyanate
- alkyl
- 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.)
- Abandoned
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J175/00—Adhesives based on polyureas or polyurethanes; Adhesives based on derivatives of such polymers
- C09J175/04—Polyurethanes
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C271/00—Derivatives of carbamic acids, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups
- C07C271/06—Esters of carbamic acids
- C07C271/08—Esters of carbamic acids having oxygen atoms of carbamate groups bound to acyclic carbon atoms
- C07C271/10—Esters of carbamic acids having oxygen atoms of carbamate groups bound to acyclic carbon atoms with the nitrogen atoms of the carbamate groups bound to hydrogen atoms or to acyclic carbon atoms
- C07C271/20—Esters of carbamic acids having oxygen atoms of carbamate groups bound to acyclic carbon atoms with the nitrogen atoms of the carbamate groups bound to hydrogen atoms or to acyclic carbon atoms to carbon atoms of hydrocarbon radicals substituted by nitrogen atoms not being part of nitro or nitroso groups
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C271/00—Derivatives of carbamic acids, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups
- C07C271/06—Esters of carbamic acids
- C07C271/08—Esters of carbamic acids having oxygen atoms of carbamate groups bound to acyclic carbon atoms
- C07C271/24—Esters of carbamic acids having oxygen atoms of carbamate groups bound to acyclic carbon atoms with the nitrogen atom of at least one of the carbamate groups bound to a carbon atom of a ring other than a six-membered aromatic ring
-
- 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
- C08G18/8064—Masked polyisocyanates masked with compounds having only one group containing active hydrogen with monohydroxy compounds
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
- C09D175/04—Polyurethanes
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2601/00—Systems containing only non-condensed rings
- C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
- C07C2601/14—The ring being saturated
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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)
- Polyurethanes Or Polyureas (AREA)
- Paints Or Removers (AREA)
- Adhesives Or Adhesive Processes (AREA)
Abstract
Disclosed are blocked polyisocyanates having a free NCO content of less than 2% by weight in which the NCO groups are blocked with .alpha.-hydroxycarboxylic acid esters of the general formula:
(I) (in which R1 and R2 are each hydrogen, alkyl, alkenyl, aralkyl or aryl group and R3 is alkyl, alkenyl, aralkyl or aryl group).
The blocked polyisocyanates are useful as adhesive or coating materials.
(I) (in which R1 and R2 are each hydrogen, alkyl, alkenyl, aralkyl or aryl group and R3 is alkyl, alkenyl, aralkyl or aryl group).
The blocked polyisocyanates are useful as adhesive or coating materials.
Description
216322~
.z. 4920 Blocked polYisocyanates, Process for their PreP~ration, and coatinq materials and coatin~ sYstems Produced therefrom The present invention relates to blocked isocyanates, to a process for their preparation and to their use in adhesives and coating materials, especially in one-pack PU stoving enamels and other coating systems.
The blocking of polyisocyanates for the temporary protection of the NCO groups is a well-established working method and is described, for example, in Houben-Weyl, Methoden der Organischen Chemie [Methods of organic chemistry] XIV/2, pp. 61-70. Curable compositions comprising blocked polyisocyanates are used, for example, in polyurethane coating materials. The coating films are cured by reacting the thermally reactivated polyisocyanates with polyols. A compilation of blocking agents which are suitable in principle can be found, for example, in Zeno W. Wicks Jr., Progress in Organic Coatings 3 (1975) 73-79, 9 (1981) 3-28.
In coating applications, in order to cure within a time of from 20 to 30 minutes, a large number of such blocking agents require temperatures of more than 160C. From an economic standpoint, they therefore have excessively high unblocking temperatures.
In the recent past, a small number of new systems have been discovered which have low stoving temperatures of around 100 to 140C and stoving times of from 20 to 30 minutes. Thus oxime-blocked polyisocyanates are described, for example, in DE-A 22 00 342, EP-A-0 432 257 and US-A-3,857,818. US-A-4,452,681, 4,452,930 and 4,452,963 describe urethane group-containing compounds, prepared from polyisocyanates and ~-hydroxy acid amides, which are employed as low-temperature crosslinking agents for both solvent-based and, in particular, water-based 23443-56~
216~226 compositions, such as electrodeposition coating materials.
Both US-A-4/976,837 and EP-A-0 500 495 claim pyrazoles for the production of stoving enamels. Owing to the elimination of amine-containing compounds, some of which remain in the coating, the oxime-blocked or a-hydroxy acid amide-blocked polyisocyanates have a tendency to undergo yellowing. In the production of stoving enamels, the properties of the pyrazole-blocked polyisocyanates in respect of reactivity and curing times are very highly dependent on the blocking agent/polysio-cyanate system employed. Only in a few systems can advantagesbe discerned.
Therefore according to the present invention, it is attempted to provide novel, cost-effective, blocked isocyanates which eliminate the blocking agents at relatively low temperatures but nevertheless remain stable at ambient temperatures. Such polyisocyanates, unblocking at around 120 to 130C, are to be suitable, particularly in combination with appropriate polyol components, for the production of one-pack (or one-can) stoving (or baking) enamels which exhibit a low yellowing tendency.
Surprisingly, it has been found that alcohols having adjacent ester functions for the blocking of polyisocyanates, alone or in conjunction with known blocking agents essentially fulfill the desired properties.
The present invention therefore provides blocked polyisocyanates havinga free NCO content of less than 2~ by mass in which NCO groups are blocked with a-hydroxycarboxylic acid esters of the general formula:
~16~226 ~- - 3 -Rl o HO - C C O R (I) (in which R and R are each hydrogen or an alkyl, alkenyl, aralkyl or aryl group and R is an alkyl, alkenyl, aralkyl or aryl group, wherein these groups may contain a further substituent including one containing a heteroatom).
These groups preferably have lO or less carbon atoms.
Preferred a-hydroxycarboxylic esters are those in which Rl is hydrogen, R is hydrogen or a methyl group and R3 is an alkyl radical having l to lO carbon atoms, more preferably l to 4 carbon atoms. Very preferred are glycolic acid esters with an alkyl group having l to 4 carbon atoms.
These compounds according to the invention are distinguished by a free NCO content of less than 2.0% by weight. Preferably, these blocked polyisocyanates have a blocked NCO content from 5 to 25~ by weight. Their ccnsistency at ambient temperature is generally liquid or solid.
The blocked polyisocyanates according to the inv~ntion can be prepared by reacting polyisocyanates with blocking agents such that, for each 0.8 to 1.2 mol of blocking agent, l NCO
equivalent of the polyisocyanate component is reacted optionally in the presence of from 0.01 to 2.0% by weight of a catalyst.
At least 10% by weight of,preferably at least 50% by weight of, more preferably entirely the blocking agents are the -hydroxy-carboxylic acid esters of the formula (I).
' - 3a -The polyisocyanates to be blocked may be any organic polyisocyanates which are suitable for the crosslinking of compounds containing active hydrogen, i.e. aliphatic 216~22~
- 4 - O.Z. 4920 (including cycloaliphatic)~ aromatic and heterocyclic polyisocyanate~ having at least two isocyanate groups and mixtures thereof. Representative examples of the polyiso-cyanates are aliphatic isocyanates such as alkylene isocyanates, for example ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 3-methylpentamethylene 1,5-diisocyanate (MPDI), hexamethylene diisocyanate (HDI), trimethylhexa-methylene 1,6-diisocyanate (TMDI), especially the 2,2,4 and the 2,4,4 i~omer and technical-grade mixtures of the two isomers, decamethylene diisocyanate and dodecamethy-lene diisocyanate, and cycloalkylene isocyanate, for example 1,3-cyclopentyl diisocyanate, 1,2-cyclohexyl diisocyanate, 1,4-cyclohexyldiisocyanate, ~,~'-diisocya-nato-1,4-dimethylcyclohexane, ~,~'-diisocyanato-1,3-dimethylcyclohexane, l-methyl-2,4-diisocyanatocyclo-hexane, 4,4'-methylenebis(cyclohexylisocyanate)(HI2MDI), and 3,5,5-trimethyl-1-isocyanato-3-isocyanato-methylcyclohexane (IPDI). Representative examples of polyisocyanates are also aromatic isocyanates such as aryl isocyanates, for example m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-biphenyl diisocyanate, 1,4-naphthalene diisocyanate and 1,5-naphthalene diiso-cyanate, and alkaryl isocyanates, for example diisocya-natodiphenylmethane (MDI), in particular the 4,4' isomer, but also technical-grade mixtures of various isomers, for example the 4,4' and 2,4' isomers, diisocyanatomethyl-benzene (TDI), in particular the 2,4 and the 2,6 isomer and technical-grade mixtures of the two isomers, 4,4'-toluidine diisocyanate, 1,3-bis(isocyanatomethyl)benzene (XDI), m-tetramethylxylylene diisocyanate (TMXDI) and polymethylenepolyphenyl isocyanate, ring-substituted aromatic isocyanates, for example dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate and chlorobiphenyl diisocyanate. Other highly suitable polyisocyanates include those which are obtainable by reacting polyi~ocyanates with themselves via isocyanate groups such as uretdiones or carbodiimide compounds which are formed by reaction of two isocyanate groups, or such - 216922g~
~_ - 5 - O.Z. 4920 as isocyanurate~, which are formed by reaction of three isocyanate groups. The polyisocyanates may likewise contain biuret or allophanate groups. Other compounds well-suited to the invention are polyisocyanate prepolymers which contain on average more than one isocyanate group per molecule. They are obtained by preliminary reaction of a molar excess of, for example, one of the abovementioned polyisocyanates with an organic material which contains at least two active hydrogen atoms per molecule, for example in the form of hydroxyl groups as in polyalkylene polyols.
Representative examples of the blocking agents are methyl glycolate, ethyl glycolate, butyl glycolate, ethyl lactate and butyl lactate.
The blocked polyisocyanates according to the invention are prepared by reacting from 0.8 to 1.2 mol of the blocking agent with one NCO equivalent of the polyisocyanate. It is possible if desired to add from 0.01 to 2.0 % by wt., preferably from O.OS to 1.0 % by wt., of a catalyst. The catalysts employed are conventional urethanization catalysts. Examples of such catalysts are metals, metal salts or metal complexes, such a~ lead tetraacetate, dibutyltin dilaurate, zinc octoate or tertiary amines such as triethylamine or 1,4-diazabicyclo[2.2.2]octane. The reaction can be carriedout at room temperature or higher temperatures, for example at between 50 and 130C.
Blocking may be carried out in bulk or in the presence of suitable solvents. The matter of whether to employ a solvent-free procedure depends largely on the subsequent application of the blocked polyisocyanate. If it is used to produce heat-curable PU powders, it is produced by a solvent-free method. When the blocked polyisocyanates according to the invention are employed as curing compo-nent in the production of solvent-containing one-pack PU
stoving enamels, preparation in solution is appropriate.
.
21-6~2~G
~- - 6 - O.Z. 4920 Suitable inert solvents are aromatic hydrocarbons, esters or ketones and, as extenders or diluants, aliphatic hydrocarbons.
The blocking of the polyisocyanate with the blocking agent is generally carried out in such a way that the blocking agent i~ metered into the polyisocyanate, which is heated to about 25 to 60C and contains from 0.05 to 1.0 % by wt. of dibutyltin dilaurate as catalyst, based on the sum of polyisocyanate and blocking agent, in about 20 to 40 % by wt. of inert ~olvent at a rate such that the temperature of the reaction mixture does not exceed 100C. When the addition of the blocking agent is at an end, the mixture is maintained at reaction temperature until almost complete reaction has taken place. In general, one NCO equivalent of the isocyanate component reacts with one mol of bloc~ing agent.
In the context of the invention it is also possible to re?lace some of the ~-hydroxycarboxylic esters employed in accordance with the invention by known blocking agents. Accordingly, the blocked polyisocyanates may contain at least 10 % by wt., preferably at least 50 %
by wt., of radicals of a-hydroxycarboxylic esters and other blocking agents, for example oximes or secondary amines, provided the combination meets the demands which are made of the blocked polyisocyanates.
The present invention also relates to adhesives, coating materials and coating systems which comprise the blocked . polyisocyanates claLmed. The ~locked isocyanates accord-ing to the invention are combined with tAe customary resins for PU coatings, i.e. preferably with hydroxyl-containing resins.
These compounds according to the invention are distin-guished in that, in combination with an appropriate polyol and in the presence of suitable catalysts, they cure within baking times of from 15 to 30 minutes at - 7 - O.Z. 4920 temperatures of from 120 to 140C.
Examples of suitable polyols are alkyd resins, polyester ~ polyols, hydroxyl-containing polyacrylates, hydroxyl-containing polyurethane polymers, hydroxyl-containing polyurea polymers, hydroxyl-containing polyether poly-mers, hydroxyl-containing epoxy polymers and hydroxyl-containing polyepoxide/amine adducts. The epoxy polymers may be free from epoxide groups or may contain epoxide groups.
The molecular weights of the polyols may vary over a wide range, depending on the nature of the polyols and on the desired property profiles of the coating materials formed by reaction with the blocked polyisocyanates according to the invention. Polyester polymers, epoxy polymers and alkyd polymers may have molecular weights in the range from 500 to 50,000, preferably between 1000 and 5000.
Acrylate polymers may po~sess molecular weights of 100,000 or more. They are usually in the range from 3000 .to 50,000.
The hydroxyl content of the polymeric polyols should be sufficient for the composition of polyol and blocked polyisocyanates to cure to give coating films having the appropriate service properties. The hydroxyl number of the polymeric polyol iB usually at least 30 mg of ROH/g, preferably between 70 and 300 mg of ~OH/g.
The blocked polyisocyanates according to the invention constitute valuable crosslinking resins for suitable polyols in the production of stoving enamels, especially in one-pack PU stoving enamels.
The formulation of adhe~ives, coating materials and other - coating systems from the blocked polyisocyanates and polyols is known in the art and therefore require~ no further de~cription here. The blocked polyisocyanate may 21~226 - - 8 - O.Z. 4920 be separate to or an integral component with the compound containing active hydrogen. Thu~, for example, a polyiso-cyanate may be bloc~ed and present as a separate compo-nent together with the polyol. Alternatively, the poly-isocyanate may also ~e partially blocked and may reactwith a polyol to give an ungelled compound. In the latter case, the resulting urethane forms an integral component with the polyol. The blocked polyisocyanate is present in both systems in a quantity which is sufficient to impart excellent curing properties to the curable composition.
The ratio of equivalents of the NCO groups of the polyisocyanate to the polyol is typically in the range from 0.1:1 to 2:1,preferably from 0.8:1 to 1.2:1.
of very great importance, finally, is the use of cata-lysts in the production of high-grade adhesives, coating materials and coating systems. Commonly, in the combina-tion of blocked polyisocyanates with resins, catalysts are used to enable effective curing at relatively low te~peratures. For example, metal salts and/or metal complexes are employed in quantities of from about 0.1 to 2.0 % by wt., in particular from 0.5 to 1.5 % by wt., based on the weight of the curable composition. The curing catalyst may be mixed with the other starting materials ~imultaneously in order to produce the composi-tion, or may be added to the composition in any usualsequence.
The heat-curable compositions which are produced using the bloc~ked polyisccyanates according to the invention may additionally comprise compounds containing active hydro-gen and, if desired, fillers, pigments and other addi-tives which are customarily used to produce heat-curable coatings.
The use of the coating composition in accordance with this invention ensures curing of the coating material at 3S temperatures of from 120 to 240C, preferably within a temperature range between 120 and 150C. In this way, 216~226 .
- ~ - 9 - O.Z. 4920 high-quality coatings or finishes having low yellowing value~ are obtained. When the coating compositions were cured under the conditions given above, it was found that the sy3tems had a greater than expected mass after stoving. The examples which follow illustrate the invention in more detail.
E~ample A. PreParation of the o-hy~oAy~Lu~ylic esters used in accordsnce with the invention a~ blockinq aqents Glycolic acid is dissolved in the respective alcohol and added to an initial suspension charge of methyl isobutyl ketone and p-toluenesulphonic acid. The reaction mixture is heated at reflux for 3-8 h. The mixture is cooled to room temperature and insoluble constituents are removed by filtration. Subsequent distillation of the filtrate yields the o-hydroxy-carboxylic ester. Table 1 gives an overview of the composition and preparation of the o-hydroxy-carboxylic esters.
-Table 1:
o-h~dros~- Se rtl~g ~e-ri-l-c~rb~llc -t-r o-hJdro~- qu-rtit~ ~lcohol q~ntlt~
c r~llc ~plo~-d ~plo~-d cld [gl [gl ~ th~l gl~collc 76 05 ~ t~ ~ol 96 12 2581~col~tc~cld ~e~L gl~colle 76 0S eh~ol 116 7Z
gl~coLct- rcld - - 216922~
- 10 - O.Z. 4920 8. ~ample~ 1 to 4 accordinq to the in~ention Preparation of polyisocyanates blocked with a-hydro~ycar~o~ylic Qsters 0.01 to 5 ~ by wt. of dibutyltin dilaurate are added to one NCO equi~alent of the polyisocyanate solution prepared at from 40 to 80C in an inert solvent. Subsequently, with stirring, from 0.8 to 1.2 mol of the a-hydroxycarboxylic ester are added in portions at a rate such that the reaction tem-perature does not exceed 100C. When the addition of the ~-hydroxycarboxylic ester is at an end, heating is continued for a further 0.5 to 2 hours at from 50 to 100C in order to complete the reaction.
Table 2 shows the composition and the chemical and physicai data of the blocked isocyanates.
Table 2:
~pl- lllocl~d Pol~LJoc~
No l-oc~ .J-!r-- NC0Uoclccd t~ g c rbc~llc co~-r~ NCO co~ r-ng--~-r tS b~ ~ ]~t b~ CI
L~~c 1 _~1 c 0 1 12 ~ 96 - 102 ~l~co~
2 L~oc~t- 2 t~l < 0 1 13 ~ -~l~col-t~
L-OC~ - I b~lqL c 0 1 11 2 63 - 65 ~l~col-~--oc~ - 3 b~ ~l c 0 1 12 6 81JCol-~.
Isocyanate 1 = 3,5,5-trimethyl-1-isocya-nato-3-isocyanatomethylcyclohexane 2S Isocyanate 2 = 3-methylpentamethylene 1,5-diisocyanate Isocyanate 3 = hexamethylene 1,6-diiso-cyanate - ; - 216~22~
O.Z. 4920 C. ExamPles I to VI according to the invention Preparation of the polyurethane coating materials ~ according to the invention The blocked isocyanates listed in Table 2, in a stoichiometric ratio with polyols in accordance with the formulations described below, are pigmented in a conventional manner with rutile TiO2 corresponding to a p.v.c. of 19 and formulated with appropriate - additives.
The polyols are for example - polyesters having a hydroxyl content of 1-5 % by weight - polyacrylates having a hydroxyl content of 1-5 %
by weight In Table 3, Examples I to VI according to the inven-tion are coating compositions. The formulated vis-co~ity is about 60 sec, measured in a DIN 4 cup at 20C. All numerical values relate to percentages by weight.
-216g221S
~ - 12 - O.Z. 4920 Table 3:
Components Examples I }I III IV V VI
Blocked polyisocyanate - - 25.0 24.2 - -5 . Blocked polyisocyanate - - - - 22.0 Blocked pol~isocyanate 25.7 25.0 Blocked polyisocyanate - - - - - 24.7 PE 1 21.4 - 21.8 PE 2 7.6 - 7.7 Acry 1 - 33.5 - 33.9 19.0 Acry 2 - - - - 16.236.5 TiO2, Rutile 31.031.2 30.329.7 28.729.7 DBTL, 10 ~ in BA 1.8 1.8 DBTA, 10 ~ in BA - - 5.2 5.2 5.1 5.1 Isophorone 3.0 3.0 3.0 2.0 3.0 1.5 3-methosy-n-butyl 5.0 5.0 5.0 4.0 5.0 2.0 acetate MOPA 2.0 - l.O
SOLVESSO 100 2.0 PC 430, 10 ~ 0.5 0.5 _ _ _ 0.5 Byk 331, 10 1 - - 1.0 1.0 1.0 PE 1 - Osyester EP-2 1439, O~N: 130 mg of gO~Ig; ~Uls AG
PE 2 - Osyester Z 1261, O~N: 120 mg of RO~/g; ~ls AG
Acry 1 - Setalus C 1187, O~N: 118 mg of RO~lg; Akzo Chemicals Trade-mark 23443-564 13 - 0.2. 4920 ~cry 2 - Setalux *C 1151, OH~: 145 mg of RO~/g; Akzo Chem~cals DBTA - Dibutyltln di~cetate catalyst, ~cima ~G
DBTL - Dibutyltin dilaur~te catalyst, Clba Ge~gy AG
MOPA - l-methoxy-2-propyl acetate, BASF AG
PC 430 - Levelllng agent, 3M Deut~chland GmbH
Byk 331 - Levelling agent, Byk-Chemie Gmb~
The formulated coating materials in the wet state are applied using a doctor blade to 1 mm steel panels and are cured under various curing conditions in a coating convection oven (CCO).
Tables 4 and 5 below are compilations of important processing data and coatings-relevant parameters.
Table 4:
ExampleTemperature of circulating air 15 No.in the CCO ~C]
- Residence time in the CCO [min]
I 2.5 3.5 6.0 12.0 30.0 * *
II 4.0 8.0 30.0 * * * *
III * ~- 4.0 5.0 15.0 30.0 45.0 IV * * 3.0 4.0 8.0 20.0 45.0 V * * * 7.0 20.0 45.0 *
VI 2.5 2.5 3.5 6.0 15.0 30.0 *
*) not tested The physical properties of the coating films, as listed in Table 5, are representative - withi.n the range of natural variation - for all of the curing conditions indicated in Table 4.
) Trade-mark 23443-564 216922~
~- - 14 - O.Z. 4920 Table 5:
E~apL- LT CE E~ E~ EI BI CG
1 25 - 35 ~ - 0 12S lB0 9 60 76 9~
II 25 - 35 ~ 0 125 160 6 50 52 8S
5 III25 - 35 ~ 0 118 1112 9 60 71 92 IV U - 35 ~ 0 125 163 9 30 76 91 ~ 25 - 35 ~ 0 125 161 8 ~0 55 90 n 2S - 35 ~ O 1~ 168 8 ~0 ~9 90 LT = Layer thickness HB = Buchholz indentation hardness, as per DIN 53 153 CH = Crosshatch, as per DIN 53 151 HR = Ronig hardness, as per DIN 53 157 EI = Erichsen indentation, as per DIN 53 156 8I = Ball impact, as per ASTM D-2794/84 GG = Gardner gloss, as per ASTM D-523
.z. 4920 Blocked polYisocyanates, Process for their PreP~ration, and coatinq materials and coatin~ sYstems Produced therefrom The present invention relates to blocked isocyanates, to a process for their preparation and to their use in adhesives and coating materials, especially in one-pack PU stoving enamels and other coating systems.
The blocking of polyisocyanates for the temporary protection of the NCO groups is a well-established working method and is described, for example, in Houben-Weyl, Methoden der Organischen Chemie [Methods of organic chemistry] XIV/2, pp. 61-70. Curable compositions comprising blocked polyisocyanates are used, for example, in polyurethane coating materials. The coating films are cured by reacting the thermally reactivated polyisocyanates with polyols. A compilation of blocking agents which are suitable in principle can be found, for example, in Zeno W. Wicks Jr., Progress in Organic Coatings 3 (1975) 73-79, 9 (1981) 3-28.
In coating applications, in order to cure within a time of from 20 to 30 minutes, a large number of such blocking agents require temperatures of more than 160C. From an economic standpoint, they therefore have excessively high unblocking temperatures.
In the recent past, a small number of new systems have been discovered which have low stoving temperatures of around 100 to 140C and stoving times of from 20 to 30 minutes. Thus oxime-blocked polyisocyanates are described, for example, in DE-A 22 00 342, EP-A-0 432 257 and US-A-3,857,818. US-A-4,452,681, 4,452,930 and 4,452,963 describe urethane group-containing compounds, prepared from polyisocyanates and ~-hydroxy acid amides, which are employed as low-temperature crosslinking agents for both solvent-based and, in particular, water-based 23443-56~
216~226 compositions, such as electrodeposition coating materials.
Both US-A-4/976,837 and EP-A-0 500 495 claim pyrazoles for the production of stoving enamels. Owing to the elimination of amine-containing compounds, some of which remain in the coating, the oxime-blocked or a-hydroxy acid amide-blocked polyisocyanates have a tendency to undergo yellowing. In the production of stoving enamels, the properties of the pyrazole-blocked polyisocyanates in respect of reactivity and curing times are very highly dependent on the blocking agent/polysio-cyanate system employed. Only in a few systems can advantagesbe discerned.
Therefore according to the present invention, it is attempted to provide novel, cost-effective, blocked isocyanates which eliminate the blocking agents at relatively low temperatures but nevertheless remain stable at ambient temperatures. Such polyisocyanates, unblocking at around 120 to 130C, are to be suitable, particularly in combination with appropriate polyol components, for the production of one-pack (or one-can) stoving (or baking) enamels which exhibit a low yellowing tendency.
Surprisingly, it has been found that alcohols having adjacent ester functions for the blocking of polyisocyanates, alone or in conjunction with known blocking agents essentially fulfill the desired properties.
The present invention therefore provides blocked polyisocyanates havinga free NCO content of less than 2~ by mass in which NCO groups are blocked with a-hydroxycarboxylic acid esters of the general formula:
~16~226 ~- - 3 -Rl o HO - C C O R (I) (in which R and R are each hydrogen or an alkyl, alkenyl, aralkyl or aryl group and R is an alkyl, alkenyl, aralkyl or aryl group, wherein these groups may contain a further substituent including one containing a heteroatom).
These groups preferably have lO or less carbon atoms.
Preferred a-hydroxycarboxylic esters are those in which Rl is hydrogen, R is hydrogen or a methyl group and R3 is an alkyl radical having l to lO carbon atoms, more preferably l to 4 carbon atoms. Very preferred are glycolic acid esters with an alkyl group having l to 4 carbon atoms.
These compounds according to the invention are distinguished by a free NCO content of less than 2.0% by weight. Preferably, these blocked polyisocyanates have a blocked NCO content from 5 to 25~ by weight. Their ccnsistency at ambient temperature is generally liquid or solid.
The blocked polyisocyanates according to the inv~ntion can be prepared by reacting polyisocyanates with blocking agents such that, for each 0.8 to 1.2 mol of blocking agent, l NCO
equivalent of the polyisocyanate component is reacted optionally in the presence of from 0.01 to 2.0% by weight of a catalyst.
At least 10% by weight of,preferably at least 50% by weight of, more preferably entirely the blocking agents are the -hydroxy-carboxylic acid esters of the formula (I).
' - 3a -The polyisocyanates to be blocked may be any organic polyisocyanates which are suitable for the crosslinking of compounds containing active hydrogen, i.e. aliphatic 216~22~
- 4 - O.Z. 4920 (including cycloaliphatic)~ aromatic and heterocyclic polyisocyanate~ having at least two isocyanate groups and mixtures thereof. Representative examples of the polyiso-cyanates are aliphatic isocyanates such as alkylene isocyanates, for example ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 3-methylpentamethylene 1,5-diisocyanate (MPDI), hexamethylene diisocyanate (HDI), trimethylhexa-methylene 1,6-diisocyanate (TMDI), especially the 2,2,4 and the 2,4,4 i~omer and technical-grade mixtures of the two isomers, decamethylene diisocyanate and dodecamethy-lene diisocyanate, and cycloalkylene isocyanate, for example 1,3-cyclopentyl diisocyanate, 1,2-cyclohexyl diisocyanate, 1,4-cyclohexyldiisocyanate, ~,~'-diisocya-nato-1,4-dimethylcyclohexane, ~,~'-diisocyanato-1,3-dimethylcyclohexane, l-methyl-2,4-diisocyanatocyclo-hexane, 4,4'-methylenebis(cyclohexylisocyanate)(HI2MDI), and 3,5,5-trimethyl-1-isocyanato-3-isocyanato-methylcyclohexane (IPDI). Representative examples of polyisocyanates are also aromatic isocyanates such as aryl isocyanates, for example m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-biphenyl diisocyanate, 1,4-naphthalene diisocyanate and 1,5-naphthalene diiso-cyanate, and alkaryl isocyanates, for example diisocya-natodiphenylmethane (MDI), in particular the 4,4' isomer, but also technical-grade mixtures of various isomers, for example the 4,4' and 2,4' isomers, diisocyanatomethyl-benzene (TDI), in particular the 2,4 and the 2,6 isomer and technical-grade mixtures of the two isomers, 4,4'-toluidine diisocyanate, 1,3-bis(isocyanatomethyl)benzene (XDI), m-tetramethylxylylene diisocyanate (TMXDI) and polymethylenepolyphenyl isocyanate, ring-substituted aromatic isocyanates, for example dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate and chlorobiphenyl diisocyanate. Other highly suitable polyisocyanates include those which are obtainable by reacting polyi~ocyanates with themselves via isocyanate groups such as uretdiones or carbodiimide compounds which are formed by reaction of two isocyanate groups, or such - 216922g~
~_ - 5 - O.Z. 4920 as isocyanurate~, which are formed by reaction of three isocyanate groups. The polyisocyanates may likewise contain biuret or allophanate groups. Other compounds well-suited to the invention are polyisocyanate prepolymers which contain on average more than one isocyanate group per molecule. They are obtained by preliminary reaction of a molar excess of, for example, one of the abovementioned polyisocyanates with an organic material which contains at least two active hydrogen atoms per molecule, for example in the form of hydroxyl groups as in polyalkylene polyols.
Representative examples of the blocking agents are methyl glycolate, ethyl glycolate, butyl glycolate, ethyl lactate and butyl lactate.
The blocked polyisocyanates according to the invention are prepared by reacting from 0.8 to 1.2 mol of the blocking agent with one NCO equivalent of the polyisocyanate. It is possible if desired to add from 0.01 to 2.0 % by wt., preferably from O.OS to 1.0 % by wt., of a catalyst. The catalysts employed are conventional urethanization catalysts. Examples of such catalysts are metals, metal salts or metal complexes, such a~ lead tetraacetate, dibutyltin dilaurate, zinc octoate or tertiary amines such as triethylamine or 1,4-diazabicyclo[2.2.2]octane. The reaction can be carriedout at room temperature or higher temperatures, for example at between 50 and 130C.
Blocking may be carried out in bulk or in the presence of suitable solvents. The matter of whether to employ a solvent-free procedure depends largely on the subsequent application of the blocked polyisocyanate. If it is used to produce heat-curable PU powders, it is produced by a solvent-free method. When the blocked polyisocyanates according to the invention are employed as curing compo-nent in the production of solvent-containing one-pack PU
stoving enamels, preparation in solution is appropriate.
.
21-6~2~G
~- - 6 - O.Z. 4920 Suitable inert solvents are aromatic hydrocarbons, esters or ketones and, as extenders or diluants, aliphatic hydrocarbons.
The blocking of the polyisocyanate with the blocking agent is generally carried out in such a way that the blocking agent i~ metered into the polyisocyanate, which is heated to about 25 to 60C and contains from 0.05 to 1.0 % by wt. of dibutyltin dilaurate as catalyst, based on the sum of polyisocyanate and blocking agent, in about 20 to 40 % by wt. of inert ~olvent at a rate such that the temperature of the reaction mixture does not exceed 100C. When the addition of the blocking agent is at an end, the mixture is maintained at reaction temperature until almost complete reaction has taken place. In general, one NCO equivalent of the isocyanate component reacts with one mol of bloc~ing agent.
In the context of the invention it is also possible to re?lace some of the ~-hydroxycarboxylic esters employed in accordance with the invention by known blocking agents. Accordingly, the blocked polyisocyanates may contain at least 10 % by wt., preferably at least 50 %
by wt., of radicals of a-hydroxycarboxylic esters and other blocking agents, for example oximes or secondary amines, provided the combination meets the demands which are made of the blocked polyisocyanates.
The present invention also relates to adhesives, coating materials and coating systems which comprise the blocked . polyisocyanates claLmed. The ~locked isocyanates accord-ing to the invention are combined with tAe customary resins for PU coatings, i.e. preferably with hydroxyl-containing resins.
These compounds according to the invention are distin-guished in that, in combination with an appropriate polyol and in the presence of suitable catalysts, they cure within baking times of from 15 to 30 minutes at - 7 - O.Z. 4920 temperatures of from 120 to 140C.
Examples of suitable polyols are alkyd resins, polyester ~ polyols, hydroxyl-containing polyacrylates, hydroxyl-containing polyurethane polymers, hydroxyl-containing polyurea polymers, hydroxyl-containing polyether poly-mers, hydroxyl-containing epoxy polymers and hydroxyl-containing polyepoxide/amine adducts. The epoxy polymers may be free from epoxide groups or may contain epoxide groups.
The molecular weights of the polyols may vary over a wide range, depending on the nature of the polyols and on the desired property profiles of the coating materials formed by reaction with the blocked polyisocyanates according to the invention. Polyester polymers, epoxy polymers and alkyd polymers may have molecular weights in the range from 500 to 50,000, preferably between 1000 and 5000.
Acrylate polymers may po~sess molecular weights of 100,000 or more. They are usually in the range from 3000 .to 50,000.
The hydroxyl content of the polymeric polyols should be sufficient for the composition of polyol and blocked polyisocyanates to cure to give coating films having the appropriate service properties. The hydroxyl number of the polymeric polyol iB usually at least 30 mg of ROH/g, preferably between 70 and 300 mg of ~OH/g.
The blocked polyisocyanates according to the invention constitute valuable crosslinking resins for suitable polyols in the production of stoving enamels, especially in one-pack PU stoving enamels.
The formulation of adhe~ives, coating materials and other - coating systems from the blocked polyisocyanates and polyols is known in the art and therefore require~ no further de~cription here. The blocked polyisocyanate may 21~226 - - 8 - O.Z. 4920 be separate to or an integral component with the compound containing active hydrogen. Thu~, for example, a polyiso-cyanate may be bloc~ed and present as a separate compo-nent together with the polyol. Alternatively, the poly-isocyanate may also ~e partially blocked and may reactwith a polyol to give an ungelled compound. In the latter case, the resulting urethane forms an integral component with the polyol. The blocked polyisocyanate is present in both systems in a quantity which is sufficient to impart excellent curing properties to the curable composition.
The ratio of equivalents of the NCO groups of the polyisocyanate to the polyol is typically in the range from 0.1:1 to 2:1,preferably from 0.8:1 to 1.2:1.
of very great importance, finally, is the use of cata-lysts in the production of high-grade adhesives, coating materials and coating systems. Commonly, in the combina-tion of blocked polyisocyanates with resins, catalysts are used to enable effective curing at relatively low te~peratures. For example, metal salts and/or metal complexes are employed in quantities of from about 0.1 to 2.0 % by wt., in particular from 0.5 to 1.5 % by wt., based on the weight of the curable composition. The curing catalyst may be mixed with the other starting materials ~imultaneously in order to produce the composi-tion, or may be added to the composition in any usualsequence.
The heat-curable compositions which are produced using the bloc~ked polyisccyanates according to the invention may additionally comprise compounds containing active hydro-gen and, if desired, fillers, pigments and other addi-tives which are customarily used to produce heat-curable coatings.
The use of the coating composition in accordance with this invention ensures curing of the coating material at 3S temperatures of from 120 to 240C, preferably within a temperature range between 120 and 150C. In this way, 216~226 .
- ~ - 9 - O.Z. 4920 high-quality coatings or finishes having low yellowing value~ are obtained. When the coating compositions were cured under the conditions given above, it was found that the sy3tems had a greater than expected mass after stoving. The examples which follow illustrate the invention in more detail.
E~ample A. PreParation of the o-hy~oAy~Lu~ylic esters used in accordsnce with the invention a~ blockinq aqents Glycolic acid is dissolved in the respective alcohol and added to an initial suspension charge of methyl isobutyl ketone and p-toluenesulphonic acid. The reaction mixture is heated at reflux for 3-8 h. The mixture is cooled to room temperature and insoluble constituents are removed by filtration. Subsequent distillation of the filtrate yields the o-hydroxy-carboxylic ester. Table 1 gives an overview of the composition and preparation of the o-hydroxy-carboxylic esters.
-Table 1:
o-h~dros~- Se rtl~g ~e-ri-l-c~rb~llc -t-r o-hJdro~- qu-rtit~ ~lcohol q~ntlt~
c r~llc ~plo~-d ~plo~-d cld [gl [gl ~ th~l gl~collc 76 05 ~ t~ ~ol 96 12 2581~col~tc~cld ~e~L gl~colle 76 0S eh~ol 116 7Z
gl~coLct- rcld - - 216922~
- 10 - O.Z. 4920 8. ~ample~ 1 to 4 accordinq to the in~ention Preparation of polyisocyanates blocked with a-hydro~ycar~o~ylic Qsters 0.01 to 5 ~ by wt. of dibutyltin dilaurate are added to one NCO equi~alent of the polyisocyanate solution prepared at from 40 to 80C in an inert solvent. Subsequently, with stirring, from 0.8 to 1.2 mol of the a-hydroxycarboxylic ester are added in portions at a rate such that the reaction tem-perature does not exceed 100C. When the addition of the ~-hydroxycarboxylic ester is at an end, heating is continued for a further 0.5 to 2 hours at from 50 to 100C in order to complete the reaction.
Table 2 shows the composition and the chemical and physicai data of the blocked isocyanates.
Table 2:
~pl- lllocl~d Pol~LJoc~
No l-oc~ .J-!r-- NC0Uoclccd t~ g c rbc~llc co~-r~ NCO co~ r-ng--~-r tS b~ ~ ]~t b~ CI
L~~c 1 _~1 c 0 1 12 ~ 96 - 102 ~l~co~
2 L~oc~t- 2 t~l < 0 1 13 ~ -~l~col-t~
L-OC~ - I b~lqL c 0 1 11 2 63 - 65 ~l~col-~--oc~ - 3 b~ ~l c 0 1 12 6 81JCol-~.
Isocyanate 1 = 3,5,5-trimethyl-1-isocya-nato-3-isocyanatomethylcyclohexane 2S Isocyanate 2 = 3-methylpentamethylene 1,5-diisocyanate Isocyanate 3 = hexamethylene 1,6-diiso-cyanate - ; - 216~22~
O.Z. 4920 C. ExamPles I to VI according to the invention Preparation of the polyurethane coating materials ~ according to the invention The blocked isocyanates listed in Table 2, in a stoichiometric ratio with polyols in accordance with the formulations described below, are pigmented in a conventional manner with rutile TiO2 corresponding to a p.v.c. of 19 and formulated with appropriate - additives.
The polyols are for example - polyesters having a hydroxyl content of 1-5 % by weight - polyacrylates having a hydroxyl content of 1-5 %
by weight In Table 3, Examples I to VI according to the inven-tion are coating compositions. The formulated vis-co~ity is about 60 sec, measured in a DIN 4 cup at 20C. All numerical values relate to percentages by weight.
-216g221S
~ - 12 - O.Z. 4920 Table 3:
Components Examples I }I III IV V VI
Blocked polyisocyanate - - 25.0 24.2 - -5 . Blocked polyisocyanate - - - - 22.0 Blocked pol~isocyanate 25.7 25.0 Blocked polyisocyanate - - - - - 24.7 PE 1 21.4 - 21.8 PE 2 7.6 - 7.7 Acry 1 - 33.5 - 33.9 19.0 Acry 2 - - - - 16.236.5 TiO2, Rutile 31.031.2 30.329.7 28.729.7 DBTL, 10 ~ in BA 1.8 1.8 DBTA, 10 ~ in BA - - 5.2 5.2 5.1 5.1 Isophorone 3.0 3.0 3.0 2.0 3.0 1.5 3-methosy-n-butyl 5.0 5.0 5.0 4.0 5.0 2.0 acetate MOPA 2.0 - l.O
SOLVESSO 100 2.0 PC 430, 10 ~ 0.5 0.5 _ _ _ 0.5 Byk 331, 10 1 - - 1.0 1.0 1.0 PE 1 - Osyester EP-2 1439, O~N: 130 mg of gO~Ig; ~Uls AG
PE 2 - Osyester Z 1261, O~N: 120 mg of RO~/g; ~ls AG
Acry 1 - Setalus C 1187, O~N: 118 mg of RO~lg; Akzo Chemicals Trade-mark 23443-564 13 - 0.2. 4920 ~cry 2 - Setalux *C 1151, OH~: 145 mg of RO~/g; Akzo Chem~cals DBTA - Dibutyltln di~cetate catalyst, ~cima ~G
DBTL - Dibutyltin dilaur~te catalyst, Clba Ge~gy AG
MOPA - l-methoxy-2-propyl acetate, BASF AG
PC 430 - Levelllng agent, 3M Deut~chland GmbH
Byk 331 - Levelling agent, Byk-Chemie Gmb~
The formulated coating materials in the wet state are applied using a doctor blade to 1 mm steel panels and are cured under various curing conditions in a coating convection oven (CCO).
Tables 4 and 5 below are compilations of important processing data and coatings-relevant parameters.
Table 4:
ExampleTemperature of circulating air 15 No.in the CCO ~C]
- Residence time in the CCO [min]
I 2.5 3.5 6.0 12.0 30.0 * *
II 4.0 8.0 30.0 * * * *
III * ~- 4.0 5.0 15.0 30.0 45.0 IV * * 3.0 4.0 8.0 20.0 45.0 V * * * 7.0 20.0 45.0 *
VI 2.5 2.5 3.5 6.0 15.0 30.0 *
*) not tested The physical properties of the coating films, as listed in Table 5, are representative - withi.n the range of natural variation - for all of the curing conditions indicated in Table 4.
) Trade-mark 23443-564 216922~
~- - 14 - O.Z. 4920 Table 5:
E~apL- LT CE E~ E~ EI BI CG
1 25 - 35 ~ - 0 12S lB0 9 60 76 9~
II 25 - 35 ~ 0 125 160 6 50 52 8S
5 III25 - 35 ~ 0 118 1112 9 60 71 92 IV U - 35 ~ 0 125 163 9 30 76 91 ~ 25 - 35 ~ 0 125 161 8 ~0 55 90 n 2S - 35 ~ O 1~ 168 8 ~0 ~9 90 LT = Layer thickness HB = Buchholz indentation hardness, as per DIN 53 153 CH = Crosshatch, as per DIN 53 151 HR = Ronig hardness, as per DIN 53 157 EI = Erichsen indentation, as per DIN 53 156 8I = Ball impact, as per ASTM D-2794/84 GG = Gardner gloss, as per ASTM D-523
Claims (17)
1. A blocked polyisocyanate having a free NCO content of less than 2% by weight in which NCO groups are blocked with a blocking agent, at least 10% by weight of the blocking agent being an .alpha.-hydroxycarboxylic acid ester of the general formula:
(I) (in which R1 and R2 are each hydrogen or an alkyl, alkenyl, aralkyl or aryl group and R3 is an alkyl, alkenyl, aralkyl or aryl group, wherein these groups may have a substituent which may contain a heteroatom).
(I) (in which R1 and R2 are each hydrogen or an alkyl, alkenyl, aralkyl or aryl group and R3 is an alkyl, alkenyl, aralkyl or aryl group, wherein these groups may have a substituent which may contain a heteroatom).
2. A blocked polyisocyanate according to claim 1, wherein R1 and R2 are each hydrogen or an alkyl, alkenyl, aralkyl or aryl group and R3 is an alkyl, alkenyl, aralkyl or aryl group, where the groups have 10 or less carbon atoms.
3. A blocked polyisocyanate according to claim 1, wherein R1 is hydrogen, R2 is hydrogen or a methyl group and R3 is an alkyl radical having 1 to 10 carbon atoms,
4. A blocked polyisocyanate according to claim 1, wherein the .alpha.-hydroxycarboxylic acid ester is a C1-4 alkyl ester of glycolic acid.
5. A blocked polyisocyanate according to claim 1, wherein the a-hydroxycarboxylic acid ester of the formula (I) is methyl glycolate, ethyl glycolate, butyl glycolate, ethyl lactate or butyl lactate.
6. A blocked polyisocyanate according to any one of claims 1 through 5, wherein at least 50% by weight of the blocking agent is the .alpha.-hydroxycarboxylic acid ester of the formula (I) and the remaining blocking agent is a member selected from the group consisting of oximes and secondary amines.
7. A blocked polyisocyanate according to any one of claims 1 through 5, wherein the blocking agent is solely the .alpha.-hydroxycarboxylic acid ester of the formula (I).
8. A blocked polyisocyanate according to any one of claims 1 through 7, wherein the polyisocyanate is an aliphatic, cycloaliphatic, aromatic or heterocyclic polyisocyanate.
9. A blocked polyisocyanate according to claim 8, wherein the polyisocyanate is 3,5,5-trimethyl-1-isocyanato-3-isocyanatomethylcyclohexane (IPDI), hexamethylene diisocyanate (HDI), 3-methylpentamethylene 1,5-diisocyanate (MPDI), trimethylhexamethylene 1,6-diisocyanate (TMDI), 4,4'-methylenebis(cyclohexyl isocyanato) (H12MDI), diisocyanatodiphenylmethane (MDI), diisocyanatomethylbenzene (TDI), 1,3-bis(isocyanatomethyl)benzene (XDI) or m-tetramethylxylylene diisocyanate (TMXDI).
10. A blocked polyisocyanate according to any one of claims 1 through 7, wherein the polyisocyanate contains a uretdione, isocyanurate, biuret or allophanate structures.
11. A process for the preparation of a blocked polyiso-cyanate which comprises reacting a polyisocyanate with a blocking agent such that, for each 0.8 to 1.2 mol of the blocking agent, 1 NCO equivalent of the polyisocyanate component is reacted in the presence of from 0.01 to 2.0% by weight of a catalyst, wherein at least 10% by weight of the blocking agent is an .alpha.-hydroxycarboxylic acid ester of the general formula:
(I) (in which R1 and R2 are each hydrogen or an alkyl, alkenyl, aralkyl or aryl group and R3 is an alkyl, alkenyl, aralkyl or aryl group, wherein these groups may contain a substituent which may contain a heteroatom).
(I) (in which R1 and R2 are each hydrogen or an alkyl, alkenyl, aralkyl or aryl group and R3 is an alkyl, alkenyl, aralkyl or aryl group, wherein these groups may contain a substituent which may contain a heteroatom).
12. A process according to claim 11, wherein R1 is hydrogen, R2 is hydrogen or a methyl group and R3 is an alkyl radical having 1 to 10 carbon atoms.
13. A coating material consisting essentially of at least one active hydrogen-containing compound and a blocked polyisocyanate of any one of claims 1 through 10.
14. A coating material according to claim 13, which further contains a catalyst in an amount of from 0.1 to 2.0%
by weight based on the total weight of the active hydrogen-containing compound and the blocked polyisocyanate.
by weight based on the total weight of the active hydrogen-containing compound and the blocked polyisocyanate.
15. A coating material according to claim 13, wherein the active hydrogen-containing compound is a polyol selected from the group consisting of alkyd resin, polyester polyol, hydroxyl-containing polyacrylate, hydroxyl-containing poly-urethane polymer, hydroxyl-containing polyurea polymer, hydroxyl-containing polyether polymer, hydroxyl-containing epoxy polymer and hydroxyl-containing polyepoxide/amine adduct and is contained in such an amount that an NCO/OH equivalent ratio is 0.1:1 to 2:1.
16. A one-pack polyurethane stoving enamel based on an active hydrogen-containing compound and a blocked polyiso-cyanate of any one of claims 1 through 10.
17. An adhesive comprising a blocked polyisocyanate of any one of claims 1 through 10.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19504530.0 | 1995-02-11 | ||
| DE19504530A DE19504530A1 (en) | 1995-02-11 | 1995-02-11 | Blocked polyisocyanates, processes for their preparation and lacquers and coating systems produced therefrom |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2169226A1 true CA2169226A1 (en) | 1996-08-12 |
Family
ID=7753691
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002169226A Abandoned CA2169226A1 (en) | 1995-02-11 | 1996-02-09 | Blocked polyisocyanates, process for their preparation, and coating materials and coating systems produced therefrom |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0726284A1 (en) |
| JP (1) | JPH08239447A (en) |
| CA (1) | CA2169226A1 (en) |
| DE (1) | DE19504530A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7041768B2 (en) | 2003-02-26 | 2006-05-09 | Bayer Materialscience Ag | Polyurethane coating systems |
| WO2009127012A1 (en) * | 2008-04-18 | 2009-10-22 | Commonwealth Scientific And Industrial Research Organisation | Polyurethanes |
| US20170029656A1 (en) * | 2015-07-28 | 2017-02-02 | Evonik Degussa Gmbh | Reactive non-aqueous dispersions for coatings, adhesives and sealants |
| WO2018148323A1 (en) * | 2017-02-07 | 2018-08-16 | Ppg Industries Ohio, Inc. | Low-temperature curing adhesive compositions |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5936055A (en) * | 1997-02-19 | 1999-08-10 | The Dow Chemical Company | Acid functionalized polyurethane adducts |
| US5955561A (en) * | 1997-12-19 | 1999-09-21 | Ppg Industries Ohio, Inc. | Hydroxy esters and amides derived from active ester urethanes and their use in film-forming compositions |
| US5905121A (en) * | 1997-12-19 | 1999-05-18 | Ppg Industries, Inc. | Active ester urethane crosslinking agents and their use in film-forming compositions |
| DE10006649A1 (en) * | 2000-02-15 | 2001-08-16 | Bayer Ag | Alcohol-blocked polyisocyanates for coil coating |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3928113A (en) * | 1973-06-14 | 1975-12-23 | Clairol Inc | Method for coating human nails |
| JPS5830904B2 (en) * | 1975-08-22 | 1983-07-02 | 武田薬品工業株式会社 | Fuck you |
| US4452681A (en) * | 1983-02-10 | 1984-06-05 | Ppg Industries, Inc. | Method of electrodeposition of coating compositions containing novel urethane curing agents |
| CA1229338A (en) * | 1983-02-10 | 1987-11-17 | Thomas C. Moriarity | Urethanes, curable compositions containing the novel urethanes, and the use of the compositions in electrodeposition |
| CA2051548C (en) * | 1990-09-18 | 1996-04-30 | Hiroshi Ueda | Resin compositions and molded articles |
-
1995
- 1995-02-11 DE DE19504530A patent/DE19504530A1/en not_active Withdrawn
- 1995-12-20 EP EP95120215A patent/EP0726284A1/en not_active Withdrawn
-
1996
- 1996-02-07 JP JP8021184A patent/JPH08239447A/en active Pending
- 1996-02-09 CA CA002169226A patent/CA2169226A1/en not_active Abandoned
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7041768B2 (en) | 2003-02-26 | 2006-05-09 | Bayer Materialscience Ag | Polyurethane coating systems |
| WO2009127012A1 (en) * | 2008-04-18 | 2009-10-22 | Commonwealth Scientific And Industrial Research Organisation | Polyurethanes |
| US20170029656A1 (en) * | 2015-07-28 | 2017-02-02 | Evonik Degussa Gmbh | Reactive non-aqueous dispersions for coatings, adhesives and sealants |
| WO2018148323A1 (en) * | 2017-02-07 | 2018-08-16 | Ppg Industries Ohio, Inc. | Low-temperature curing adhesive compositions |
| US11952514B2 (en) | 2017-02-07 | 2024-04-09 | Ppg Industries Ohio, Inc. | Low-temperature curing adhesive compositions |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0726284A1 (en) | 1996-08-14 |
| DE19504530A1 (en) | 1996-08-14 |
| JPH08239447A (en) | 1996-09-17 |
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