Organic compounds -- part of the class 532-570 series – Organic compounds – Unsubstituted hydrocarbyl chain between the ring and the -c-...
Reexamination Certificate
2001-03-23
2002-09-10
Kifle, Bruck (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Unsubstituted hydrocarbyl chain between the ring and the -c-...
Reexamination Certificate
active
06448394
ABSTRACT:
The invention relates to a process for the preparation of an N-alkyl or N-aryl carbamoyl derivative, and in particular a blocked isocyanate. A blocked isocyanate is a compound which contains an isocyanate with a blocking agent.
Blocked isocyanates are used in the preparation of polyurethanes and polyurea. A blocked isocyanate can in a stable manner be mixed with a polyol at temperatures of up to, for example, 150° C. Upon an increase in temperature, the blocking agent splits off from the isocyanate group, so that the released isocyanate can react with the polyol that is present to form a polyurethane.
A method for the production of blocked isocyanates is described in GB-A-1415730. GB-A-1415730 describes a process wherein an N-(1-chloro-1-alkenyl)-carbonic acid chloride is reacted with an amine, to form a blocked isocyanate.
A process for the preparation of an N-alkyl or N-aryl carbamoyl derivative is disclosed in DE-A-2712931. In said process, an isocyanate is contacted with caprolactam, as a result of which a caprolactam-blocked isocyanate is formed.
A drawback of the process disclosed in DE-A-2712931 is that a reaction with isocyanate involves safety risks.
The aim of the invention is to provide a safer process.
This aim is achieved in that an amine is contacted with a carbonic acid derivative according to the following general formula:
where fragments X in the form of XH are a lactam, oxime, imide or triazole.
In the process according to the invention no isocyanate is present in the reaction mixture.
An advantage of the process according to the invention is that a blocked isocyanate is formed in which no free isocyanate is present anymore.
Since the known reaction disclosed in DE-A-2712931 does not proceed quantitatively, a small amount of free isocyanate remains present in the reaction mixture. To reduce the vapor pressure of this free isocyanate, the isocyanate is often trimerized by means of a temperature increase before being contacted with lactam. This is done in particular for isophorone diisocyanate (IPDI) and hexamethylene diisocyanate (HMDI). An advantage and a consequence of the fact that no free isocyanate is present in the reaction mixture in the process according to the invention, is that there is no need to carry out the above-mentioned trimerization reaction.
A further advantage of the process according to the invention is that it can be used to prepare an N-alkyl or N-aryl carbamoyl derivative of which the nitrogen is secondary and the derivative is a lactam, oxime, imide or triazole. These are compounds that cannot be prepared via the known isocyanate route.
In the framework of this invention amines may be mono-, di-, tri-, polyamines or mixtures of these, Examples of di- and triamines are diamino octane, diamino nonane, diamino dodecane, trisamino nonane, diamino dioxydecane, diamino dioxododecane, bishexamethylene trisamine and Jeffamines. Other suitable amines are oligomers, as reaction products of two components. Examples of oligomers are the reaction products of hexamethylene diamine with adipic acid, urea, carbonyl biscaprolactamate (CBC) and with 1 or 2 caprolactam molecules
An advantage of the process according to the invention for the preparation of blocked isocyanates on the basis of oligomeric amines is the fact that the fragments (X), which are split off in the reaction between the carbonic acid derivative and the amine, can readily be removed from the reaction mixture as XH. This contrasts with the removal of the triethylamine salt that is released in the preparation of blocked isocyanates on the basis of phosgene and triethylamine.
Contacting an amine with the carbonic acid derivative can optionally be effected in a solvent. Preferably, this is done by dissolving the carbonic acid derivative according to formula I in a suitable first solvent. Suitable solvents are generally non-protic solvents such as esters, ethers, cyclic carbonates, cyclic amides and hydrocarbons. Subsequently the amine, dissolved in a second solvent, can slowly be added, with continuous stirring, to the solution of the carbonic acid derivative. Second solvents are preferably also chosen from the same group of non-protic solvents.
Preferably, the first and the second solvent are the same.
After the addition of the dissolved amine the mixture is stirred for some time at a temperature between room temperature and 150° C. Above 150° C. the blocking agent can readily be split off. Stirring preferably takes place at a temperature between 50 and 100° C., after which the N-alkyl or N-aryl carbamoyl derivative formed can be separated from the reaction mixture according to known techniques.
The product obtained by the process according to the invention can be very widely applied in technically different fields, both in thermosetting and in thermoplastic applications. Examples are powder paint compositions, coating systems based on water or solvent and can or coil coating systems, inks, toners, film formers for glassfibre sizings, adhesives, hot melts and in rubber compositions.
Unmodified or partly modified polymers according to the invention can generally be used in powder paint compositions, in can or coil coating compositions and in solvent-based coating compositions.
According to a preferred embodiment of the invention the products obtained by the process according to the invention can be used as a crosslinker in thermosetting powder paint compositions.
Thermosetting powder paints have a better resistance to chemicals than thermoplastic powder paints. As a result of this, intensive efforts have for a long time been made to develop crosslinkers and polymers for thermosetting powder coatings. Attempts are still being made to find binder compositions for thermosetting powder paints with a good flow behaviour, good storage stability and a good reactivity. A thermosetting powder paint binder composition generally contains more than 50 wt. % polymer and less than 50 wt. % crosslinker.
The product obtained according to the invention can be used in a powder paint composition as a crosslinker in combination with a hydroxyl functional polymer.
The hydroxyl functional polymer is preferably a polyester, a polyacrylate or a mixture of both. Preferably, the polyester has a hydroxyl number of between 20 and 100 mg of KOH/gram of resin and an acid number of less than 10 mg of KOH/gram of resin. Preferably, the polyacrylate has a hydroxyl number of between 40 and 150 mg of KOH/gram of resin and an acid number of less than 20 mg of KOH/gram of resin.
The weight ratio between the polymer containing hydroxyl groups and the crosslinker can be between about 95:5 and about 50:50, and preferably between 93:7 and 70:30. This ratio depends on, among other factors, the hydroxyl number of the polymer.
The hydroxyl functional polymers can be mixed with the blocked crosslinker by extrusion, for example, at a temperature of about 100° C. The curing takes place at temperatures of, for example, between about 130° C. and about 170° C. (in, for example, about 10-40 minutes), and preferably above about 150° C.
Additives, such as for example fillers, catalysts, curing agents, flow agents and/or stabilizers and, if required, pigments, can be added to the coating systems, preferably before the extrusion.
Suitable polyesters can be obtained via customary preparation methods from carboxylic acids or equivalents thereof. The use of mainly aromatic carboxylic acids is preferred. Examples include phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, trimellitic acid, 3,6-di-chlorophthalic acid, tetrachlorophthalic acid and, in so far as available, equivalents like anhydrides, acid chlorides or lower alkyl esters thereof. Generally, the carboxylic acid component comprises at least 50 wt. %, and preferably at least 70 mol %, isophthalic acid and/or terephthalic acid.
Preferably, the diol component of the polyester is an aliphatic diol. Examples include ethylene glycol, propane-1,2-diol, propane-1,3-diol, butane-1,2-diol, butane-1,4-diol, butane-1,3-diol, 2,2-di-methylpropane diol-1,3 (=neopentyl gl
Loontjens Jacobus A.
Plum Bartholomeus J. M.
DSM N.V.
Kifle Bruck
Pillsbury & Winthrop LLP
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