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
2000-01-27
2001-12-04
Cain, Edward J. (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...
Reexamination Certificate
active
06326430
ABSTRACT:
The present invention relates to the use of specific crosslinked cationic homopolymers as thickening agents for acidic aqueous compositions. Typical acidic aqueous compositions which can be thickened by the crosslinked cationic homopolymers described in the invention are those for domestic use, such as toilet cleaners and laundry softeners.
The first ones comprise, as active ingredients, acids or mixtures of acids such as hydrochloric, phosphoric, maleic, citric, oxalic, malonic, sulfamic acid and analogs, whereas laundry softeners are compositions which comprise cationic surfactants as active ingredients. Examples of these surfactants are long alkyl chain dialkyldimethylammonium salts which are, however, used in limited amounts due to their biodegradability problems. In fact, they have been replaced, partly or completely, by cationic surfactants belonging to the family of the so-called “ester quats” (G. R. Whalley, Happi, February 1995, page 55; I. Shapiro et al., Cosmetics and Toiletries, 109, 77, 1994), which are quaternary ammonium salts, containing at least a group Z—CO—O—, in which Z is a straight or branched (C
8-25
) alkyl, saturated o unsaturated, characterized in that the non-carbonylic oxygen of such group is linked to the quaternary nitrogen through a straight or branched (C
1-5
), preferably (C
2-3
), alkylene chain.
Typical non-limiting examples of “ester quats” are
A) imidazole derivatives of formula
B) di-hydroxypropylammonium esters of formula
C) amidoaminoesters of formula
D) esters of formula
In the above mentioned compounds, W is hydrogen or a suitable group for quaternising the nitrogen atom(s), such as methyl, ethyl, hydroxyethyl and analogs, the groups Z can be the same or different, and Y is essentially a chloride, bromide, iodide, hydrogen sulfate or methosulfate anion.
The acidic aqueous compositions which are referred to in the present invention often contain other auxiliary components, such as perfumes, dyes, optical bleachers and analogs, and are in the form of very fluid aqueous systems, i.e. with viscosity values close to those of water. For this reason, they suffer from problems which make their use awkward, such as the outflow of the liquid from the container in an undesired amount, with the consequent use of excessive amounts of the composition which, as in the case of laundry softeners, can, although temporarily, affect the properties of the fabric, or involve repeated rinses, with a waste of water, time and power. A further problem, mainly connected with marketing reasons, is that compositions with fluidity similar to water lack that “creamy” consistence that better gives the idea of softness.
On the other hand, when very sloped or even vertical ceramic surfaces are to be cleaned, as is the case of tiled walls, wash-basins or water-closets, the fluidity of the composition makes it to quickly flow over said surfaces, thus decreasing the contact times between the active components of the composition and soil, without attaining its homogeneous distribution on them, so that remarkable amounts of the composition itself are necessary to obtain the desired effect.
Conventional thickeners have been used, such as cellulose derivatives, guar gum, xanthane gum, water-soluble anionic polymers either non crosslinked or partially crosslinked, with unsatisfactory results.
It is anyway common practice to thicken aqueous compositions by adding synthetic polymer compounds, whose nature depends on the intended use of the thickened composition, in order to overcome this and other drawbacks. The choice of the suitable thickening agent depends on the type of the composition and on its use. Anionic or cationic polymeric thickeners can be used. Very frequently, they are crosslinked copolymers of acrylamide and other ethylenically unsaturated monomeric units, in which the crosslinking agent is present in amounts which depend on the desired crosslinking degree and, as a consequence, on the intended use of the copolymer (see U.S. Pat. Nos. 3,968,037 and 4,806,345). EP 395 282 suggests the use of crosslinked cationic homopolymers and copolymers to thicken particularly acidic aqueous systems (pH<4), for example solutions for cleaning metals, for removing rust, germicides, detergents for ceramic articles such as those based on citric, phosphoric and hydrochloric acids, in which the crosslinking agent has to be present in very specific amounts (from 5 to no more than 45 ppm—parts per million) of the polymer weight, in that the best performances are reportedly attained only within such range of crosslinking agent. In practice, however, EP 395 282 discloses the use of acrylamide/dimethylaminoethyl methacrylate copolymers quaternised with CH
3
Cl. Finally, EP 494 554 describes cationic acrylamide/dimethylaminoethyl methacrylate copolymers quaternised with CH
3
Cl, in which the weight ratio of the two monomers is preferably 80:20, crosslinked with 50 to 100 ppm of bisacrylamidoacetic acid. These crosslinked cationic copolymers are used as thickening agents in laundry softeners for domestic use. However, acrylamide, which is still present in the final products, is known to be a highly toxic compound. Therefore, a thickening agent for acidic aqueous compositions whose preparation does not involve the use of said substance, is highly requested also from the industrial point of view.
As stated above, the present invention relates to the use of specific crosslinked cationic homopolymers as thickening agents for acidic aqueous compositions. More particularly, said crosslinked cationic homopolymers are homopolymers of cationic monomers of formula I
crosslinked with a crosslinking agent present in amounts ranging from not less than 50 to about 600 ppm of the homopolymer total weight.
A further object of the present invention relates to the use of the above mentioned crosslinked cationic homopolymers as thickening agents for acidic aqueous compositions containing an “ester quat” cationic surfactant.
In formula I, R is hydrogen, (C
1-4
)-alkyl, or the radical CH
2
COOH, R
1
is hydrogen, methyl, carboxy, or the radical CH
3
—CH═CH, R
2
is methylene or a straight or branched (C
2-4
) alkylene moiety, R
3
, R
4
and R
5
are independently hydrogen or (C
1-4
) alkyl and X is chlorine, bromine, iodine, hydrogen sulfate or methosulfate.
(C
1-4
)Alkyl substantially means methyl, ethyl, propyl, isopropyl, n.-butyl, isobutyl, sec.-butyl and tert.-butyl, whereas a straight or branched (C
2-4
) alkylene moiety substantially means ethylene, 1,3-propylene, 1- and 2-methyl-ethylene, 1,4-butylene, isobutylene and analogs.
A preferred group of compounds of formula I are those in which R is hydrogen or methyl, R
1
is hydrogen or methyl, R
2
is methylene, ethylene or 1,3-propylene, R
3
, R
4
and R
5
are independently hydrogen, methyl or ethyl and X is chlorine, bromine, hydrogen sulfate and methosulfate.
A second preferred group of compounds of formula I are those in which R is hydrogen or methyl, R
1
is hydrogen, R
2
is methylene or ethylene, R
3
, R
4
and R
5
are methyl and X is chlorine, hydrogen sulfate and methosulfate.
All the compounds containing at least two ethylenically unsaturated moieties can be used as crosslinking agents. Illustrative examples of said crosslinking agents are divinyl benzene, allyl acrylates and methacrylates, diacrylates and dimethacrylates of glycols and polyglycols, butadiene, 1,7-octadiene, allyl-acrylamides and allyl-methacrylamides, bisacrylamidoacetic acid, N,N′-methylene-bisacrylamide and polyol polyallylethers, such as polyallylsaccharose and pentaerythritol triallylether. Preferred crosslinking agents are allyl-acrylamides and allyl-methacrylamides, bisacrylamidoacetic acid and N,N′-methylene-bisacrylamide. The most preferred crosslinking agent is N,N′-methylene-bisacrylamide.
The crosslinking agents are used in amounts ranging from not less than 50 ppm to about 600 ppm of the homopolymer total weight. Preferably, the crosslinking agent is present in amounts from about 60 to about 250 ppm of the homopolymer total weight. C
3V Sigma S.p.A.
Birch & Stewart Kolasch & Birch, LLP
Cain Edward J.
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