WO1999020725A1

WO1999020725A1 - Thickening agents for acidic aqueous compositions

Info

Publication number: WO1999020725A1
Application number: PCT/EP1998/006049
Authority: WO
Inventors: Ferruccio Berte'; Gianmarco Polotti
Original assignee: 3V Sigma S.P.A.
Priority date: 1997-10-17
Filing date: 1998-09-23
Publication date: 1999-04-29
Also published as: AU1025799A; IT1295355B1; ITMI972351A1

Abstract

The use of cationic linear homopolymers as thickening agents for acidic aqueous compositions, for example detergents for removing lime scales from ceramic or metal surfaces, for removing rust, laundry softeners and the like. The cationic linear homopolymers are homopolymers of cationic monomers of formula (I). Acidic aqueous compositions thickened with said cationic linear homopolymers.

Description

THICKENING AGENTS FOR ACTDIC AQUEOUS COMPOSITIONS

The present invention relates to the use of specific cationic linear homopolymers as thickening agents for acidic aqueous compositions. Typical acidic aqueous compositions which can be thickened by the cationic linear homopolymers described in the invention are those for domestic use, such as detergents for removing lime scales from ceramic or metal surfaces, for removing rust, laundry softeners and the like.

Generally, the compositions for removing lime, scales and rust comprise, as the active ingredients, acids or mixtures of acids such as hydrochloric, phosphoric, maleic, citric, oxalic, malonic, sulfamic and analogs, whereas laundry softeners are compositions which comprise cationic surfactants as the active ingre- dients. 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. halley, Happi, February 1995, page 55; I. Shapiro et al.., Cosmetics and Toiletries, 109 , 11 , 1994), which are quaternary ammonium salts, containing at least a group Z—CO—0— , in which Z is a straight or branched

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 (C₁_₅), preferably { ^2-2 ^ ' ^alkγle e chain.

Typical representative, non-limiting examples of "ester quats" are

A) imidazole derivatives of formula

B) di-hydroxγpropylammonium esters of formula

)₂ • WY

C) amidoaminoesters of formula

WY Z-CO-0-CH₂-CH₂-NH-CH₂-CH₂-CH₂-NH-CO-Z D) esters of formula

CH₂-CH₂-0-CO-Z

I

CH₃--N • WY

I

CH₂-CH₂-O-CO-Z

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 ethosulfate anion.

The acidic aqueous compositions which are referred to in the present invention often contain other auxiliary components, such as perfumes, dyes, optical brighteners 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 US 3 968 037 and US 4

806 345). EP 395 282 suggests the use of acrylamide cationic copolymers crosslinked with N,N- methylenebisacrylamide 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, whereas EP 494 554 describes cationic copolymers of acrylamide/dimethylaminoethyl ethacrylate quaternized with CH Cl, in which the weight ratio of the two monomers is preferably 80 : 20, which copolymers are cross-linked 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 cationic linear homopolymers as thickening agents for acidic aqueous compositions. More particularly, the present invention relates to the use of specific cationic linear homopolymers as thickening agents for acidic aqueous compositions having pH <. 4.5.

Said cationic linear homopolymers are homopolymers of cationic monomers of formula I:

in which R is hydrogen, (C^_^) alkyl, or the radical CH₂COOH, R-L is hydrogen, methyl, carboxy, or the radical CHg—CH=CH, R₂ is methylene or a straight or branched (C₂_^) alkylene moiety, Rg, R^ and R^ are independently hydrogen or (^cι_4) alkyl and X is chlorine, bromine, iodine, hydrogen sulfate or methosulfate.

(C^_^)Alkyl substantially means methyl, ethyl, propyl, isopropyl, n. -butyl, isobutyl, sec. -butyl and tert. -butyl, whereas a straight or branched (^c -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-, is hydrogen or methyl, R is methylene, ethylene or 1,3-propylene, R3, R^ and R₅ are independently hydrogen, methyl or ethyl and X is chlorine, bromine, hydrogen sulfate or methosulfate.

A second preferred group of compounds of formula I are those in which R is hydrogen or methyl, R^ is hydrogen, R₂ is methylene or ethylene, Rg, R^ and Re are methyl and X is chlorine, hydrogen sulfate or methosulfate . The cationic linear homopolymers used for the purposes of the present invention are added to the acidic aqueous compositions in amounts ranging from about 0.01 to about 5% of the weight of the compositions themselves. Preferably, the used amounts vary from about 0.1 to about 3.5% of the composition weight. In case acidic aqueous compositions comprising an "ester quat", cationic surfactant are to be thickened, the used amounts preferably range from about 0.1 to about 1.5% of the composition weight. Therefore, a further object of the present invention comprises acidic aqueous compositions thickened with about 0.01 to about 5% by weight of one or more cationic linear homopolymers described in the present invention and, preferably, with about 0.1 to about 3.5% of the composition weight.

It has surprisingly been found that the thus thickened acidic aqueous compositions are easy to handle and to use, they flow out from the container only in the desired amounts and keep the substantial transparence of the corresponding non thickened compositions. Moreover, the thus thickened acidic aqueous compositions proved to be stable to storage, as substantially neither sedimentation products nor appreciable changes in viscosity are observed, even after several days. The cationic linear homopolymers used as thickening agents for acidic aqueous compositions, according to what described in the present invention, are commercial products (POLYQUATERNIUM(^R) 37 - CTFA;

PRAESTOL(^R) 444K; ZETAG<^R) 88N), or can be prepared according to the usual polymerization techniques, as described hereinbelow and in the following examples. A preferred technique is the reverse emulsion polymerization in which, for example, an aqueous solution of the selected monomer is emulsified in a phase consisting of one or more water-immiscible organic liquids. The water-immiscible organic liquids are, generally, oily liquids, such as straight or branched, (C₅_₂₀) saturated hydrocarbons, vaseline oil, aromatic hydrocarbons such as benzene, toluene and xylenes, halo solvents, or mixtures thereof. The oily phase can contain an emulsifying system, typically one having an HLB (Hydrophilic-Lipophilic Balance) ranging from about 2 to about 7, comprising, for example, sorbitan esters, glycerol esters and analogs or mixtures thereof, to quicken the dispersion of the aqueous phase which, in addition to the monomer of formula I, also contains one of the polymerization initiators commonly used in the art, such as the product marketed as WAKθ^(R) V 50. The polymerization is carried out at temperatures ranging from about room temperature to about 100°C, and is completed in substantially quantitative yields in a time which can range from about 1 to about 12 hours. The desired cationic linear homopolymer can be recovered in the solid form, if desired, by distillation of the reaction mixture under vacuum. Said solid form is then ground and sieved to obtain a powder which is easily dispersible in the acidic aqueous composition. Alternatively, a homogeneous dispersion of the polymer in the oily phase, both in the hydrated and in the anhydrous forms, can be obtained by azeotropical distillation of the water. In this case, it is preferable to add, at the end of the process, a given amount of a phase inversion surfactant with HLB ranging from about 8 to about 16, such as ethoxylated lauryl alcohol with ethoxylation degree from 4 to 12, which does not affect the stability of the emulsion but quickens the dispersion of the emulsion when added to the acidic aqueous compositions. This oily homogeneous, dispersion can be added as it is to the acidic aqueous composition. For the purposes of the present invention, the use of the cationic linear homopolymers in the form of solid dispersible powders is preferred.

The preparation of the aqueous acidic composition is also carried out conventionally, adding the fluid composition with the given amount of cationic linear homopolymer, or with a mixture of said homopolymers, either as dispersible solid powders or in the form of oily homogeneous dispersions, so as to obtain a composition having the desired viscosity and rheology.

The following examples further illustrate the invention. Preparative example A

Preparation of cationic linear homopolymers as powders

A solution A is prepared, consisting of 438.0 g of a 75% solution of dimethylaminoethyl methacrylate quaternised with CHgCl in demineralized water, 0.1 g of DISSOLVINEW D-40 and 1.5 g of 10% WAKθ^(R) V-50 in demineralized water. Solution B is then prepared, consisting of 150 g of n-decane and 15 g of SPAN(^R) 80.

Solution A is emulsified in solution B. The resulting emulsion is poured into a polymerization reactor and, after removing oxygen by nitrogen bubbling, the polymerization is carried on at 60 "C for 6 hours.

Upon distillation under vacuum at temperatures comprised between 20 and 120°C, a solid is recovered, which is ground and sieved (hole diameter: 1 - 2 mm), to obtain an easy-to-use powder which is easily dispersible in an aqueous medium.

Preparative example B

Preparation of cationic linear homopolymers as emulsions

A solution A is prepared, consisting of 438.0 g of a 75% solution of dimethylaminoethyl methacrylate quaternised with CHgCl in demineralized water, 0.1 g of DISSOLVINE(^R) D-40 and 1.5 g of 10% WAKO<^R) V-50 in demineralized water. A solution B is then prepared, consisting of 250.0 g of vaseline oil, 75.0 g of n- decane and 15.0 g of SPAN^(R) 80. Solution A is emulsified in solution B. The resulting emulsion is poured into a polymerization reactor and, after removing oxygen by nitrogen bubbling, the polymerization is carried on at 60°C for 6 hours. First, water is distilled off azeotropically between 90 and 110°C, then n-decane is also distilled. The mixture is cooled at room temperature, and subsequently added with 20.0 g of ethoxylated lauryl alcohol with ethoxylation degree 7, thus obtaining a homogeneous, stable dispersion of the linear cationic homopolymer in vaseline oil, having a dull white appearance and a viscosity of 1800 cps (centipoises) , measured with a Brookfield RVT viscosimetre, spindler 3, at 20 °C and 20 rpm. The resulting product is used as such to thicken aqueous acidic compositions.

Table 1 reports the viscosities of a commercially available strongly acidic detergent composition for removing lime scales from ceramic surfaces, (VIAKAL(^R), PROCTER & GAMBLE Italia S.p.A.), respectively non thickened and thickened with 0.5, 1.0 and 1.5% by weight of the cationic linear homopolymers of the Preparative example A. The viscosities were measured with a. Brookfield RVT viscosimetre (20 rpm, spindler 5) and are expressed in cps (centipoises).

Table 1

Ex. Homopolymer Starting Viscosity viscosity after 15 at 20°C days at 40 °C

Comp. 0.0 20 20

1 0.5 160 130

2 1.0 650 520

3 1.5 1460 1300

Comp.: comparative example.

The thickened compositions did not substantially show clouding. Viscosity and rheology remained unchanged up to more than 30 days.

Table 2 reports the viscosities of 5% aqueous solutions of a cationic surfactant used as active ingredient for softening compositions (DEHYQUART' ^R ' AU

36, Henkel), respectively non thickened and thickened with 0.3% by weight of the cationic straight homopolymers of the Preparative example A. The viscosities were measured with a Brookfield RVT viscosimetre (20 rpm, spindler 5) and are expressed in cps (centipoises).

Table 2

Ex. Homopolymer Starting Viscosity viscosity after 7 days at 20°C at 40°C

comp . 0.0 50 50 4 0.3 650 625

comp. : comparative example

Claims

1. The use of cationic linear homopolymers of cationic monomers of formula I:

in which R is hydrogen, (C_1-4) alkyl, or the radical CH₂COOH, R_╧ç is hydrogen, methyl, carboxy, or the radical CHgΓÇöCH=CH, R₂ is methylene or a linear or branched (C₂_. ₄) alkylene moiety, Rg, R₄ and R₅ are independently hydrogen or (C_1-4) alkyl and X is chlorine, bromine, iodine, hydrogen sulfate or methosulfate, as thickening agents for acidic aqueous compositions.

2. The use of cationic linear homopolymers as claimed in claim 1, in which R is hydrogen or methyl, R_╧ç is hydrogen or methyl, R₂ is methylene, ethylene or 1,3- propylene, Rg, and R^ are independently hydrogen, methyl or ethyl and X is chlorine, bromine, hydrogen sulfate and methosulfate, as thickening agents for acidic aqueous compositions.

3. The use of cationic linear homopolymers as claimed in claim 1, in which R is hydrogen or methyl, _╧ç is hydrogen, R₂ is methylene or ethylene, Rg, R and Re are methyl and X is chlorine, hydrogen sulfate and methosulfate, as thickening agents for acidic aqueous compositions.

4. The use of cationic linear homopolymers as claimed in any one of claims 1 - 3, as thickening agents for acidic aqueous compositions, in the form of solid dispersible powders.

5. The use of cationic linear homopolymers as claimed in any one of claims 1 - 4 as thickening agents for acidic aqueous compositions having pH <. 4.5.

6. Acidic aqueous compositions thickened with one or more cationic linear homopolymers as claimed in any one of claims 1 - 4.

7. Acidic aqueous compositions as claimed in claim 6, comprising from about 0.01 to about 5% of the composition weight of one or more cationic linear homopolymers as claimed in any one of claims 1 to 4.

8. Acidic aqueous compositions as claimed in claims 6 and 7, comprising from about 0.1 to about 3.5% of the composition weight of one or more cationic linear homopolymers as claimed in any one of claims 1 to 4.