Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-06-16
2001-11-13
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S591000, C524S839000, C524S840000
Reexamination Certificate
active
06316539
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to water-dilutable resins, suitable after neutralisation as pigment paste resins, obtainable by converting aldehyde or ketone-based hard resins with multi-functional isocyanates and at least one isocyanate-reactive component.
2. Description of the Related Art
Aldehyde or ketone-based hard resins, abbreviated in the industry to aldehyde or ketone resins, have been known for some considerable time. Due to their specific paint properties such as light colour, resistance to saponification and yellowing, compatibility with other paint binders and very good solubility in polar organic solvents, these hard resins are important raw materials for nitro-cellulose and alkyd resin paints. They have also achieved a major practical significance in special areas of application, such as base resins for solvent-containing universal pigment pastes. However, given the demand for environmentally compatible paints, aldehyde and ketone resins have a significant disadvantage for paint manufacturers and users: they are insoluble in water.
Patent literature contains only a few attempts to manufacture stable, aqueous, dispersions based on aldehyde and ketone resins, as an example described in U.S. Pat. No. 4,644,028 (corresponds to DE-A 34 06 474), in which a protective colloid and special co-polymer are also used.
A further method of making these resins water-soluble or water-dispersible is described in co-pending U.S. patent application Ser. No. 09/166,524, whereby the (hydroxyl-group-containing) aldehyde or ketone resins are converted using acid-group-containing polymers under condensation conditions. After (partial) neutralisation of the remaining acid groups, the condensates become water-dilutable. The condensation process however, significantly increases the size of the molecules; this decreases the level of compatibility with other resins. If the paste resins as described in this application are used in stoving paints, a slight to significant yellowing is observed. In the case of pigmented paints, this can lead to colour changes.
It has been known from U.S. Pat. No. 5,962,582 (corresponds to EP-A 0 838 485) to react hydroxy functional aldehyde or ketone resins with polycarboxylic acids, or esters, halides or anhydrides thereof, to make them water-reducible. The compounds thus obtained have freely accessible carboxyl groups which can cause incompatibility with pigments. Another method is described in U.S. Pat. No. 5,919,859 (corresponds to EP-A 0 838 486), where such aldehyde or ketone resins are reacted with hydrophilic isocyanates made by reaction of (polyfunctional)isocyanates with compounds that have, in addition to their hydrophilic or potentially hydrophilic, at least one isocyanate-reactive group which comprises an active hydrogen atom according to the Zerevitinov test. These products, however, have a fixed ratio of hydrophilic groups and (unreacted) isocyanate groups. Moreover, this process requires a two-step reaction. It is desirable, compared with this state of the art, to provide a simple and easily adaptable process which leads to a variety of products with different properties.
SUMMARY OF THE INVENTION
In accordance with the present invention, water-dilutable urethane-modified aldehyde or ketone-based resins ABCD are provided which are obtained by converting mass fractions in the reaction mixture of
10 to 90% aldehyde or ketone resins A, with a hydroxyl number of 20 to 300 mg/g, softening temperature of 60 to 140° C. and a number average molar mass M
n
of 500 to 3000 g/mol;
5 to 30% multi-functional isocyanates B with an average of at least 2 isocyanate groups per molecule;
0 to 30% aliphatic acids C, each with at least one acid group and at least one group that can react with isocyanate, creating a urethane or urea structure and also,
0 to 70% of an aliphatic polyether D with a number average molar mass M
n
of 200 to 8000 g/mol, and at least one hydroxyl group per molecule,
wherein the total of the mass fractions of educts A to D is always 100% and at least one of the educts C and D is used and if necessary, subsequent neutralisation of the products ABCD with aqueous ammonia or amines, provided a compound according to C is used.
In further accordance with the present invention, there is provided a process for the synthesis of such urethane-modified aldehyde or ketone-based resins ABCD, which involves converting components A through D at increased temperatures, preferably at 30 to 200° C.
The resins according to the present invention show as little yellowing as possible when heated. The hydrophilic modification in these modified resins create only the slightest possible increase in the size of the molecule.
Further objects of this invention, and the features and advantages of the present invention will be set forth in, or be apparent from, the description that follows.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
It was found that it is possible to convert aldehyde and ketone resins with at least di-functional isocyanates and hydrophilic modification agents that have at least one isocyanate-reactive group and at least one hydrophilic, non-ionic or anionic group in the molecule. Combinations of such non-ionic and anionic hydrophilic modification agents can also be used.
The aldehyde or ketone resins A are formed though self-condensation or cocondensation together with formaldehyde, of aliphatic, cycloaliphatic or mixed aliphatic-aromatic ketones or aldehydes.
The aldehyde or ketone resins A can preferably be obtained by condensing (cyclo)aliphatic oxo-compounds A1 selected from (cyclo) aliphatic ketones A11 and aliphatic aldehydes A12 together with urea and its derivatives A2 (hereinafter described jointly as “urea”).
For the purposes of this invention, urea derivatives A2 include N-alkylated, N-arylated or N-acylated urea, where a minimum of one and a maximum of 3 amide hydrogen atoms are substituted by an alkyl, aryl or acyl radical. Suitable alkyl radicals are linear, branched, and cyclic aliphatic radicals with 1 to 20 hydrogen atoms, suitable aryl radicals are (also alkyl-substituted)aryl radicals with 5 to 14 hydrogen atoms such as phenyl, naphthyl, o-tolyl or (p-phenyl)phenyl radicals. Acyl radicals are R-CO radicals, in which R can be the alkyl or aryl radicals mentioned here. Naturally, the amide hydrogen atoms can also carry various substitutes of the stated type. Such urea derivatives where an alkyl radical with 2 or 4 hydrogen atoms links the nitrogen atoms together, e.g. ethylene and propylene urea (2-imidazolidon or tetrahydro-2-pyrimidon) and their alkyl, acyl and aryl derivatives, where at least one amide hydrogen atom is retained, can also be used.
The aldehyde and ketone resins A, as already described, can be obtained by condensing ketones together with aldehydes and urea, ketones with urea or aldehydes with urea, and show preferably a hydroxyl number of 20 to 300 mg/g, a softening temperature of 60 to 140 C. and a number average molar mass of 500 to 3000 g/mol. These resins are usually produced by alkali-catalysed condensation of appropriate oxo-compounds in the presence of urea. Suitable ketone resins are derived predominantly from cycloaliphatic ketones A11 with preferably 5 to 12 hydrogen atoms in the ring such as cyclohexanone or its alkyl derivatives, whereby the cycloaliphatic ring can carry one or several alkyl groups and the alkyl groups each have 1 to 8 hydrogen atoms such as methyl cyclohexanone, 2-ethylhexyl cyclohexanone and tertiary butyl cyclohexanone. The resins can be obtained from these ketones or their mixtures by known methods (see Ullmann, 4
th
Edition, 12, p. 551, 1976). Other suitable resins A are obtained by condensing aldehydes A12 in the presence of urea, substituted urea or their derivatives according to A2. Thus, the aliphatic aldehyde A12 is preferably linear or branched and has 2 to 20, preferably 4 to 10 hydrogen atoms. Condensates from iso-butyraldehyde, formaldehyde and urea (see Ullmann, 5
th
Edition, A23, p. 104 f) are particularly preferr
Hobisch Gerald
Morre Peter
Tuemmler Peter
Niland Patrick D.
Propat, LLC
Vianova Resins AG
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