Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2001-01-26
2003-05-20
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C252S182210, C528S067000, C428S423100, C427S385500, C560S132000
Reexamination Certificate
active
06566481
ABSTRACT:
The present invention relates to polyisocyanates of the formula (I)
OCN—R
1
—[—NX—CO—O—R
2
—O—CO—NX—R
1
—]
n
—NCO (I)
in which the units R
1
, X and R
2
have the following meanings:
R
1
is a unit of the formula (II)
—CH
2
—CH
2
—CH
2
—CH
2
—CH
2
—CH
2
— (II),
X is hydrogen or a unit of the formula (III)
—CO—NH—R
1
—NCO (III)
with the proviso that at least one of the units X in the polyisocyanates of the formula I is a unit of the formula III; and
R
2
is a 4-, 5- or 6-membered cycloalkylene radical in which up to 4 hydrogen atoms may be substituted by C
1
to C
4
alkyl radicals and one or two methylene units may be substituted by an oxygen atom, a sulfur atom and/or a tertiary nitrogen atom which additionally carries a C
1
to C
4
alkyl radical, or
is a C
2
to C
4
alkylene radical in which inserted between 2 carbon atoms or between one carbon atom and a hydrogen atom there is a 4-, 5- or 6-membered cycloalkylene radical in which up to 4 hydrogen atoms may be substituted by C
1
to C
4
alkyl radicals and one or two methylene units may be substituted by an oxygen atom, a sulfur atom and/or a tertiary nitrogen atom which additionally carries a C
1
to C
4
alkyl radical,
and the index n is 1, 2 or 3.
The invention additionally relates to isocyanate mixtures and to 2-component coating compositions comprising these isocyanates; to coating processes in which these 2-component coating compositions are used; and to the coated articles produced by these processes. Crosslinking polyisocyanates and binder components having isocyanate-reactive groups are widely known in the form of, for example, 2-component (2 K) coating materials (cf. Kunststoff Handbuch, Volume 7, Polyurethane, 2
nd
edition, 1993, Carl Hanser Verlag Munich Vienna, pp. 599 to 642, and M. Bock, Polyurethane Für Lacke und Beschichtungen, Vincentz-Verlag, Hannover, 1999). These 2-component coating compositions comprise as binder, for example, a polymeric polyol and as crosslinker component (hardener) a compound having two or more free isocyanate groups.
The service properties of coating materials whose polymeric binders have been crosslinked with the isocyanates are much better than those systems comprising low molecular mass binders. This relates in particular to service properties such as
insensitivity to mechanical exposure such as tension, strain, impact or abrasion;
resistance to moisture (in the form, for example, of water vapor) and dilute chemicals;
resistance to environmental influences such as temperature fluctuations and UV radiation; and
high gloss of the coated surfaces.
The hardeners (gelling agents) are expected not only to give the cured coatings the abovementioned service properties but also to improve, or at least have very little adverse effect on, the processing properties of the coating materials prior to their application.
So that the coating materials can be applied without problems by customary techniques, for example, by spraying them onto the surface to be coated, the coating materials are intended to possess a limited viscosity. Consequently, 2-component coating materials normally comprise solvents. The high solvent content of these coating materials itself causes problems however, since the coating-material processors have to take complex measures to avoid atmospheric emission of the solvents released when the coating materials are applied and dried. The search has therefore been on for hardeners which do not greatly increase the viscosity of the binder-containing component or which, even better, reduce it. These hardeners themselves of course must not display any noticeable volatility at room temperature, as is the case with customary commercial monomeric isocyanates such as hexamethylene diisocyanate or isophorone diisocyanate.
In addition, following their application, the 2-component coating compositions should cure as rapidly as possible so that the coated articles, following the application, may be subjected rapidly to further processing or use.
Polyisocyanates containing allophanate and biuret groups are known, for example, from EP-A-496 208, 524 501, 566 037 and WO 99/36455, where they are recommended for use as hardeners in 2-component coating systems. Suitable structural components include aliphatic monoalcohols and all customary isocyanates.
EP-303 150 discloses polyisocyanates containing allophanate groups, which are derived inter alia from diisocyanates and aliphatic alkanediols. The structural components from the group of the cyclic alkanediols and hexamethylene diisocyanate are present in these documents only in the context of lists of the suitable isocyanate and alcohol components. As evident from the experimental section of these documents, the focus is on polyisocyanates containing allophanate and biuret groups which are derived from noncyclic alcohols.
The allophanates derived from these alcohols have the disadvantage, in particular, that the 2 K coating systems produced with them are relatively slow to cure and even following complete curing still have a level of surface hardness which is inadequate for many applications.
Although the properties of the hardeners disclosed therein satisfy in most respects the customary requirements imposed on the processing properties of the uncured liquid coating systems which comprise these hardeners, and on the service properties of the coatings produced with the coating materials, these hardeners still appear in need of improvement with regard to the viscosity of the coating systems, their rate of cure, and the hardness of the coatings produced with them.
It is an object of the invention to provide this improvement.
We have found that this object is achieved by the compounds of the formula (I) defined at the outset, by mixtures and 2-component coating compositions comprising these compounds, and by articles coated with these 2-component coating compositions. The polyisocyanates of the formula (I) according to the invention are derived preferably from alcohols such as 1,3- or 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,3-cyclopentanediol or tetramethyl-1,3-cyclobutanediol.
Among these, particular preference is given to those wherein
n=1 and both units X are units of the formula III (diisocyanates Ia), or
n=1, one of the two units X is hydrogen and the other unit X is a unit of the formula III (diisocyanates Ib).
The polyisocyanates of the invention are normally prepared by
(i) reacting hexamethylene diisocyanate with a
divalent 4-, 5- or 6-membered cycloaliphatic alcohol in which up to 4 hydrogen atoms attached to a carbon atom may be substituted by C
1
to C
4
alkyl radicals and one or two methylene units may be substituted by an oxygen atom, a sulfur atom and/or a tertiary nitrogen atom which additionally carries a C
1
to C
4
alkyl radical, or
divalent C
2
to C
4
alkanediol in which inserted between 2 carbon atoms or between one carbon atom and a hydrogen atom there is a 4-, 5- or 6-membered cycloalkylene radical in which up to 4 hydrogen atoms may be substituted by C
1
to C
4
alkyl radicals and one or two methylene units may be substituted by an oxygen atom, a sulfur atom and/or a tertiary nitrogen atom which additionally carries a C
1
to C
4
alkyl radical,
the molar ratio of hexamethylene diisocyanate to the abovementioned alkanediols being from 50:1 to 3:1, preferably from 30:1 to 5:1, in the presence or absence of a catalyst which accelerates the formation of allophanates and urethanes,
(ii) deactivating the catalyst, if present, and
(iii) removing any unreacted isocyanate.
The reaction may be performed, for example, in the manner described in EP-A-524 501.
Examples of the catalysts used are quaternary ammonium carboxylates, such as N,N,N-trimethyl-N-(2-hydroxypropyl)ammonium 2-ethylhexanoate, quaternary ammonium hydroxides, or organotin or organozinc compounds.
The reaction is generally conducted at temperatures from 50 to 180° C.
The reaction is generally continued until from 3 to 8 times the molar amount of isocyanate groups corresponding to the molar
Baumgart Hubert
Bitter Simone
Bruchmann Bernd
Mohrhardt Günter
Renz Hans
BASF - Aktiengesellschaft
Gorr Rachel
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
LandOfFree
Polyisocyanates with allophanate groups derived from... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polyisocyanates with allophanate groups derived from..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polyisocyanates with allophanate groups derived from... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3063234