Coating processes – With post-treatment of coating or coating material – Solid treating member or material contacts coating
Reexamination Certificate
1999-11-12
2001-04-17
Cameron, Erma (Department: 1762)
Coating processes
With post-treatment of coating or coating material
Solid treating member or material contacts coating
C427S384000, C427S321000, C528S072000, C560S024000, C560S115000, C560S157000
Reexamination Certificate
active
06217941
ABSTRACT:
The present invention relates to a family of isocyanates which are modified to give them a surfactant property.
The present invention relates to isocyanate-based compounds and compositions (which can be partially masked, but this is not the preferred embodiment). The invention is also directed toward the process for using them, their use for making coatings and the coatings thus obtained. The invention relates more particularly to compositions which are (self)dispersible in aqueous phase.
In order to give a better understanding of the invention it has appeared appropriate to make the following reminders.
In the present description, the particle size characteristics often refer to notations of the type d
n
in which n is a number from 1 to 99. This notation is well known in many technical fields, but is slightly rarer in chemistry, and it may thus be useful to recall its meaning. This notation represents the particle size such that n% (by weight, or more exactly by mass, since weight is not an amount of matter but rather a force) of the particles is less than or equal to said size.
In the description hereinbelow, the polydispersity index will be used, which is defined as
I=
(
d
90
−d
10
)/
d
50
In the paints and varnishes sector, diisocyanates are widely used, in particular alkylene diisocyanates (for example those sold under the brand Tolonate®) and derivatives thereof of biuret type or trimers thereof.
However, two problems remain incompletely solved to date, namely:
the use of organic solvents, whose presence is reputed to be toxic and harmful to the environment;
the need to provide on the market non-volatile products, which has led to the molecules being made heavier, by oligomerizing the diisocyanates; this solution is not entirely satisfactory since it uses an elaborate, and thus expensive, function to solve the problem.
Needless to say, these problems must be solved while at the same time satisfying the constraints intrinsic to coatings.
To make films of paints or of varnishes, a dispersion or an emulsion containing the isocyanate, which may be blocked, on the one hand, and a dispersion or a solution of polyol, on the other hand, are mixed together.
The mixture of the dispersions, which can also contain pigments, in particular titanium dioxide, the dispersion of which is improved by the present invention, and fillers, is then applied to a support in the form of a film with the aid of the standard techniques for using industrial paints. When the preparation contains blocked isocyanates, the film plus support assembly is cured at a temperature which is sufficient to release the isocyanate functions and to condense them with hydroxyl groups of the polyol particles. However, it should be recalled that masked or blocked products have a significantly higher cost price than non-masked products.
The use of organic solvents is increasingly being criticized by the authorities in charge of safety at work, since these solvents, or at least some of them, are reputed to be toxic or chronotoxic. For this reason, efforts are being made to develop more and more techniques which replace the solvent-medium techniques in order to overcome the drawbacks associated with solvents.
One of the solutions most frequently used lies in the use of emulsions or dispersions in water. On account of the reactivity of water with isocyanates, this solution is especially used for masked isocyanates.
In order not to end up between Scylla and Charybdis, a major stumbling block is to be avoided, namely the deterioration of one or more of the essential qualities of the coatings [smooth nature (to avoid the “orange-peel” appearance), hardness, resistance to solvents, etc.]; in particular, poor adhesion of the coating to its support should be feared. The reason for this is that many surfactants are reputed to impair the integrity of the link between the coating and its support and are known and used to undermine the attachment between a polymer and a support (cf., for example DE-OS 3,108,537).
When unmasked or incompletely masked isocyanates are used, their useable lifetime remains less than a few hours, in general one or two hours.
Thus, it is important not to encounter any difficulties during the emulsification or dispersion of the isocyanates.
Accordingly, one of the aims of the present invention is to provide a compound and a composition which, by mixing in water or, more specifically, in an aqueous phase, gives an emulsion without it being necessary therefor to use specific techniques and/or plants.
Another aim of the present invention is to provide a compound and a composition of the above type which does not disrupt the coating operations.
Another aim of the present invention is to provide a compound and a composition of the above type whose solvent content is less than ⅕, advantageously less than {fraction (1/10)}, on a mass basis relative to said composition. Needless to say, it is preferable for there to be as little solvent as possible, or even none at all.
These aims and others which will become apparent hereinbelow are achieved by means of compounds of formula (I) and of compositions, in which they comprise at least one compound of formula (I)
in which m is equal to zero or, advantageously, to 1;
in which Iso is a (poly)isocyanate residue (after removal of an isocyanate function);
in which R
10
is chosen from:
a negative charge;
a hydrocarbon-based residue (i.e. a residue containing hydrogen and carbon atoms) whose point of attachment [i.e. the atom bearing the open bond] is a carbon;
in which R
11
is chosen from:
a negative charge;
a group of formula II:
in which R′
10
is chosen from hydrocarbon-based residues (similar to or different from R
10
) and a negative charge whose point of attachment [i.e. the atom bearing the open bond] is a carbon
in which R′
11
is (are) chosen from hydrocarbon-based residues whose point of attachment [i.e. the atom bearing the open bond] is a carbon (similar to or different from R
10
and R′
11
) and a negative charge.
Although this does not form part of the preferred compounds, it should be noted that when the similar or different organic substituents (R
10
; R′
11
; R′
10
) do not comprise a polyethylene glycol chain fragment, it is preferable for them to be C
8
to C
12
alkyl, advantageously branched, or a C
12
to C
16
aralkyl or a C
10
to C
14
alkylaryl.
It is desirable for at least one of the similar or different organic substituents (R
10
; R′
11
; R′
10
) to contain a polyethylene glycol chain fragment advantageously of at least 5, preferably of at least 7, ethylene oxide units. In other words, it is desirable for at least one of the organic substituents to correspond to the same formula as the substituents of E in the general formula I. More specifically, at least one of the organic substituents (R
10
; R′
11
; R′
10
) corresponds to the formula:
where R
5
represents an arm containing not more than two carbon-based chain members where n is an integer chosen between 0 and 30, advantageously between 5 and 25, preferably between 9 and 20 (closed intervals, i.e. including the limits);
where R
1
represents a hydrocarbon-based radical advantageously chosen from optionally substituted aryls and alkyls.
Said lipophilic part R
1
is generally chosen from alkyl groups [in the present description alk-yl is taken in its etymological sense as the hydrocarbon-based residue of an alkan-ol after ignoring the alcohol (or -ol) function]; and aryl groups. When the number of ethylene glycol functions is not more than 5, the simple alkyls are advantageously branched, advantageously C
8
to C
12
, the aralkyls are C
12
to C
16
, the alkylaryls are C
10
to C
14
and the simple aryls are C
10
to C
16
. If not, the lipophilic part can vary widely, especially when the number of ethylene glycol units is greater than 10, and can thus constitute a hydrocarbon-based radical of at least 1, advantageously of at least 3, and containing not more than 25, a
Bernard Jean-Marie
Jeannette Thierry
Nabavi Minow
Cameron Erma
Rhodia Chimie
Seugnet Jean-Louis
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