Blocked oligomeric isocyanates, their production and use

Details Blocked oligomeric isocyanates, their production and use Blocked oligomeric isocyanates, their production and use

2000-12-08

2002-08-20

Yoon, Tae H. (Department: 1714)

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...

C528S076000, C524S463000, C524S590000, C524S591000, C524S839000, C427S389900

Reexamination Certificate

active

06437077

ABSTRACT:

BACKGROUND OF THE INVENTION
A popular way of conferring an oil-repellent and/or water-repellent finish on textile material is to use fluorocarbon polymers which provide a certain air and vapour permeability and also an easy care finish, to produce, for example, breathable finishes which are impermeable to water. For general use it is desirable for the finish to have certain fastnesses, particularly cleaning fastnesses, among which the fastness to washing, especially the permanence to washing, plays a particular role; a problem in this is that an impairment of the oleophobic and/or hydrophobic effect of the finish due to a clean with customary household detergents (by washing or shampooing, for example) requires a thermal after treatment, for example at 140° C. or higher (by ironing, for example), to be at least partially recovered—provided there is still product on the substrate after the clean. It is therefore especially desirable for the original properties (particularly the oil- and water-repellent properties and the vapour permeability or the easy care properties) to be essentially intact after one or more cleaning or washing operations, even without a thermal aftertreatment, if possible.
DE 19615116 A1 describes blocked polyisocyanates as crosslinker resins for organic polyhydroxy compounds for clearcoating baking finishes, these blocked polyisocyanates being prepared by reacting an isocyanurate-group-containing (cyclo)aliphatic polyisocyanate with a nonionic hydrophilic component (a Carbowax, for example), a monofunctional blocking agent and a hydrazide-group- containing stabilizing component and optionally certain chain extenders in a certain quantitative ratio, by first reacting the starting polyisocyanate in a non-exhaustive manner with the hydrophilic component and then with the blocking agent and thereafter reacting with the stabilizer and optionally with the chain extender.
EP 0537578 A2 describes the use, together with fluorochemicals, of blocked polyisocyanates which contain polyalkylene ether and have built-in ionic groups for the hydrophobicizing and oleophobicizing finishing of textiles. Such ionically modified products have the disadvantage that they are not necessarily compatible with other products of opposite ionicity, for example anionically modified products and synthetic resin components having a cationic character, since this can lead to precipitates in an aqueous medium.
Later U.S. Pat. No. 5,714,082 describes water- and oil-repellent, soil-repellent finishes with fluoro-chemicals, the use of an extender of the hydrocarbon urethane type (there the nonionic product HCT-3) in Example 42 thereof being designated as contributing to “deficiencies”.
It has now been found that using the hereinbelow defined mixtures (G) of blocked oligomeric isocyanates surprisingly makes it possible to improve the oil- and water-repellent properties and also the fastnesses of the finishes mentioned at the outset.
SUMMARY OF THE INVENTION
The invention relates to the defined mixtures (G), compositions comprising these mixtures, the production of the mixtures and their use.
In a first aspect, the invention accordingly provides self-dispersible mixtures (G) of oligomeric isocyanates (C) reacted in part with polyethylene glycol monoalkyl ether (A), which optionally contains propyleneoxy units, and optionally with a chain extender (K) and exhaustively blocked with an isocyanate-blocking pyrazole (B).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The self-dispersible mixtures (G) can be formulated with water and optionally further additives to form aqueous dispersions (D).
The process for the production of the self-dispersible mixtures (G) is especially characterized in that
in a first process step
(a) a minor proportion of the isocyanate groups in the oligomeric isocyanate (C) are reacted in the absence of protogenic solvents with polyethylene glycol monoalkyl ether (A), which optionally contains propyleneoxy units, to form a product (U1) and this product (U1) is then optionally converted into a product (U2) which has a higher NCO-based equivalent weight and which still contains reactive NCO groups,
and in a second process step
(b) the remaining isocyanate groups are exhaustively blocked with isocyanate-blocking pyrazole (B).
For the production of the aqueous dispersions (D), the mixtures (G) thus produced can, preferably directly after their production, be mixed with water and optionally further additives.
As oligomeric isocyanates (C) are suitable generally known isocyanates, advantageously having two to ten NCO groups, for example hydrocarbon oligoisocyanates or oligomers of hydrocarbon diisocyanates, especially
(C
1
) oligomers of aliphatic diisocyanates or
(C
2
) diphenylmethane diisocyanate or polyphenylenepolymethylene polyisocyanates.
The monomeric aliphatic diisocyanates from which the oligomers (C
1
) derive preferably have at least one isocyanate group bonded to a methylene. The oligomeric isocyanates (C
1
) can be for example di-, tri- or tetramers of aliphatic, optionally cyclic diisocyanates having for example 2 to 16, preferably 4 to 10, carbon atoms in the basic hydrocarbon skeleton. Of these, hexamethylene diisocyanate, isophorone diisocyanate and 2,4,4-trimethylhexylene-1,6-diisocyanate are preferred, especially hexamethylene diisocyanate. The oligomers can be cyclic or open-chain; suitable trimers include in particular those having an isocyanurate or biuret structure, while suitable dimers include especially those having a uretidione structure; optionally it is also possible to use oligomers thereof.
The ether-forming alkyl radicals in (A) are in principle discretionary, but are preferably of low molecular weight; they preferably contain 1 to 4 carbon atoms. If desired, (A) can also contain propyleneoxy groups, in which case, however, the ethyleneoxy groups preferably outweigh the propyleneoxy groups.
The polyethylene glycol monoalkyl ethers (A), which optionally contain propyleneoxy units, preferably conform to the average formula
R—(O—CH
2
—CH
2
)
n
—OH  (I),
where
R is C
1-4
-alkyl-(O-propylene)
m
-,
n is from 5 to 30 and
m is from 0 to 10,
subject to the proviso that m is ≦⅓ of n.
is preferably from 8 to 24, particularly preferably from 12 to 20.
m is advantageously ≦¼ of n and is for example from 0 to 4, preferably zero.
In the first process tep (a), the oligomers (C) are first reacted with oligoethylene glycol monoalkyl ether (A), which optionally contains propyleneoxy units, the quantitative ratio of (A) to (C) being selected in such a way that only a portion of the available isocyanate groups is reacted with (A). The mixing ratio of (A) to (C) is advantageously selected in such a way that more than one mole equivalent of (C) is used per mole of (A). One equivalent of (C) is the weight, determinable by titration, which corresponds to one NCO group. One mole equivalent of (C) is this number in grams. The equivalents ratio of (A) to (C) is consequently the ratio of the number of moles of (A) to the number of mole equivalents of (C). This ratio is chiefly within the range from 1/50 to 1/2, preferably within the range of 1/40 to 1/4, particularly preferably within the range from 1/30 to 1/10.
The reaction of (A) with (C) can be carried out in the presence or absence of solvents, in which case suitable solvents are advantageously non-protogenic solvents, for example propylene carbonate, acetone, methyl ethyl ketone or methyl isobutyl ketone. When no (K) is used, the reaction is preferably carried out in the absence of solvents. The reaction takes place for example at elevated temperature, advantageously >30° C., for example at temperatures within the range from 60 to 95° C., and advantageously under an inert atmosphere, for example under argon or preferably nitrogen.
The reaction of (A) with (C) first gives rise to an alkyl polyglycol ether urethane product (U1), which contains urethane groups resulting from the reaction of the hydroxyl group in (A) with a portion of the isocyanate groups in (C) and preferably conforming to the fo

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