CA2177125C - Fabric conditioning composition - Google Patents

Abstract

Fabric softening compositions containing more than 2% of a cationic fabric softener, an amphoteric deposition polymer having a molecular weight greater than 1000 and being substantially free from anionic detergent active, are disclosed. The polymer acts as a deposition aid to reduce the adverse effect of anionic surfactant from the wash cycle being carried into the rinse cycle and forming a complex with the softener.

Description

C---),9 FABRIC CONDITIONING COMPOSITION

This invention relates to a fabric conditioning composition which is substantially free of anionic detergent and is particularly suitable for conditioning (e.g. softening) fabrics in the rinse step of a fabric laundering process.
The invention particularly relates to conditioning in the presence of anionic detergent carried over from the washing step of the fabric laundering process.

It is known to add fabric conditioning agents comprising cationic materials such as quaternary ammonium salts or imidazolinium salts to the rinse step of a fabric laundering process. As a result of the use of anionic materials for soil removal from fabrics in the preceding wash step, anionic materials find their way into the rinse water. This problem is common in countries where water is used sparingly and will become more common as machine manufacturers move to lower water consumption machines for increased energy efficiency.
Anionic 'carry-over' can have disadvantageous effects on cationic fabric softening materials added to the rinse water.
The anionic and cationic materials react together to form a complex and thereby reduce the quantity of cationic charged material available for deposition on the wash load.

Several proposals have been made to solve this problem.
GB 2039 556 discloses the use of a soluble monoalkyl quaternary ammonium salt in conjunction with the more usual dialkyl softening quaternary. Unfortunately the benefit of this solution is small relative to the increased formulation cost.

C.`39 A second solution, which also seeks to provide increased cationic charge to neutralise the anionic, is described in US 4179382. This patent specification suggests that use of cationic polymers which provide a high density of positive charge will improve softening performance. The problem with such polymers is that they give rise to product stability problems when used at high enough levels to be of practical use and they are uneconomic.

EP 063 899 suggests a different approach. An inorganic polymer such as aluminium chlorohydrate precipitates metal hydroxide or hydrated oxide at a pH of less than 7.5. The =~
precipitate is said to facilitate deposition of the softener.
' The disadvantage of this solution is that the inorganic polymer has to be used at very high levels (12.5 to 37.5% of the cationic level) to be effective. This makes it unattractive from an economic and an environmental viewpoint.
GB 2 195 652 teaches that anionic/cationic complexes provide a softening effect when deposited on fabric. The problem with such complexes is that they need to be preformed and administered in special ways if grease spot formation is to be avoided. The extent of softening is also rather limited.

EP 426304 describes a rinse conditioner containing polysiloxane, a cellulose ether and an optional fabric softener material. Soap is the preferred fabric softener material and is deposited with the polysiloxane to give the softening effect.
EP 276 999 discloses a fabric softening composition which comprises of a cationic fabric softener and cellulose ether as a deposition aid to mitigate the effects of anionic carry over from the main wash. However cellulose ethers are only ettective as a deposition aid when there is a high level of anionic carry over.

The advantage of the present invention is that it may be used in rinse steps where there is moderate anionic detergent active resulting from carry-over from the wash steps. Thus the formulations of the invention perfume and soften the wash load, even when anionic carryover occurs.
The present invention provides a fabric softening composition comprising more than 2% of a cationic fabric softener and being substantially free from anionic detergent active, characterised in that the composition contains an amphoteric deposition polymer, said polymer having i) positive and negative charged units ii) a molecular weight greater than 1,000 iii) a neutral unit or units having a molecular weight no greater than t;.`:3e combined molecular weight of the charged units.
The amphoteric polymer preferably has a molecular weight of at least 2000 and desirably at least 6000.
The invention also provides for the use of an amphoteric polymer having a molecular weight of at least 1000 preferably at least 2000 and desirably at least 6000 in a fabric softening composition as a deposition aid.
It is preferred if the amphoteric deposition polymer has a structure comprising the following units:

a) a positively charged unit derivable from a monomer salt wherein the cation of the salt has a formula:

R1 - N` - R2 wherein Rl and R2 are independently selected from C1-C4 alkyl groups; R3 is a C1-C4 alkyl group or a C2-C4 alkenyl group and R4 is a C2-C4 alkenyl group, a C1-C4 alkyl acrylate, a C1-C4 alkyl methacrylate, a C1-C4 alkyl methacrylamide, or a C1-C4 alkyl acrylamide;

b) a negatively charged unit having a carboxylate group derivable from a monomer having a formula:

C = C

R, ( CH2 ) nCOzRB

wherein R5, R6, R7 and R. are independently selected from Hl or a C1-C4 alkyl group or a(CHZ ) nCOORB in which n is an integer between 0 and 6.

Where the monomer for b) comprises 2 or more carboxyl groups, the ring closed condensation product may also be employed as the monomer. For example maleic acid (where n is 0 R5,R6 and R8 are H, and R, is -COZH,) may be present as maleic anhydride depending on the pH of the reaction mixture.

C_.59 2177125 it is preferred if charged unit (a) is derived from the monomer cation selected from the group consisting of trimethyl ammonium(ethyl methacrylate), trimethyl ammonium (ethyl acrylate) and trimethyl ammonium propyl methacrylamide. It is especially preferred if the monomer cation has the following formula:
( CH2=CH-CH2 ) Z-N- ( CH3 ) 2 Other suitable monomer cations include those where R4 is of the general formula CH2 = C

0 = C - X - Rlo wherein R9 is H or CH31 Rlo is a C2_6 preferably C2 to Cõ
alkylene group and X is 0 or NR9.
The monomer cation thus contains at least one ethylenically unsaturated moiety. This moiety combines with other monomers upon polymerisation. Where the cation contains only one such moiety the quaternary nitrogen group is present in the polymer as a pendant substituent on the polymer chain. Where the cation contains two or more ethylenically unsaturated moieties as in, for example a dimethyldiallyl ammonium cation, formation of a heterocyclic ring may occur during polymerisation. For example (CH2=CH-CH2) 2N` (CH3) 2, upon polymerisation is believed to form a repeating monomer unit of the following structure:

CHz - CH - CH2 ( CH3 ) 2N~ ~ I

It is preferred if the negatively charged unit (b) is selected from the group consisting of of acids, esters and salts of methacrylate, beta carboxyl acrylate, maleate, itaconate and fumarate. Especially preferred as the negatively charged unit is acrylate.

The units of similar charge may be grouped together to provide a block copolymer or randomly spaced to provide a random copolymer as desired.

It is advantageous if the ratio of positively charged units to negatively charged units within the amphoteric polymer is in the range from 1:4 to 4:1. It is preferred if this ratio of positively charged units to negatively charged units is in the range of 1:2 to 3:1. In order to provide an optimum combination of performance and stability characteristics.
Suitably the amphoteric polymers may be any molecular weight.
Low molecular weight polymers have a lower viscosity which generally may be employed to improve the processability of the composition whilst polymers having a higher molecular weight may be desirable in order to provide a thickening effect as desired. Suitably the molecular weight of the amphoteric.polymer is above 6000 and may be above 25,000, conveniently in the range from 40,000 to 1,000,000 and especially from 100,000 to 500,000.

The amphoteric deposition polymer may further comprises a neutral unit. If present the neutral unit has a molecular weight no greater than the total molecular weight of the charged units. Suitably the monomer of the neutral unit comprises an alkyl, preferably C1 to C4 (meth)acrylate. In this cases the carboxyl group is present in the neutral unit a carboxylic ester. The alkyl moiety optionally has a hydroxyl substituent. An example of a suitable neutral unit is an hydroxy propyl acrylate derivative.

The amphoteric polymer is preferably present in the product in an amount 0.05 - 2% by weight and most preferably 0.1 - 1%
by weight.

Preferably the composition contains more than 2%, more preferably more than 3.5% cationic fabric softener and most preferably more than 5% cationic fabric softener.

Preferably the weight ratio of deposition agent to cationic fabric softener lies in the range 1:4 to 1:100, more preferably 1:4 to 1:50 preferably 1:10 to 1:45.
The cationic fabric softener may be any suitable cationic surfactant which has fabric softening properties. Suitable fabric softening materials and mixtu.r.,:~s thereof are well cnown in the art, particularly from "Surface Active Agents 2~) And Detergents", Anthony M. Schwartz et al, first published in 1949 (Interscience Pubs., New York) and reprinted in 1958 and 1977 (latterly by Robert E. Krieger Publishing Co.), "Synthetic Detergents", Milwidsky and Davidson, published in 1972 (Chem. Rubber Co., Cleveland, Ohio), and "Household and r_ndustrial fabric Conditioners", Noyes Data Corporation, -1~ublished in 1980.

~ationic materials which are most useful are quaternary ammonium salts, wherein at least one higher molecular weight group and two or three lower molecular weight groups are linked to a common nitrogen atom to produce a cation and ~,;rherein the electrically balancing anion is a halide, acetate or lower alkosulphate ion, such as chloride or methosulphate.
-he higher molecular weight substituent on the nitrogen is preferably a higher alkyl group, containing 12 to 18 or 20 carbon atoms, such as coco-alkyl, tallowalkyl, hydrogenated tallowalkyl or substituted higher alkyl, and the lower :_olecular weight substituents are preferably l--wer alkyl of C._,59 2177125 to 4 carbon atoms, such as methyl or ethyl, or substituted lower alkyl. One or more of the said lower molecular weight substituents may include an aryl moiety or may be replaced by an aryl, such as benzyl, phenyl or other suitable substituent. A preferred quaternary ammonium salt is a di-higher alkyl, di-lower alkyl ammonium halide, such as di-tallowalkyl dimethyl ammonium chloride or di-hydrogenated tallowalkyl dimethyl ammonium chloride, and other quaternary ammonium chlorides will also usually be preferred. For biodegradability the higher molecular weight group may be linked to the nitrogen atom via an ester group. Examples of suitable ester linked quaternary ammonium-compounds are listed in EP 0 239 910-A (P&G) In addition to the cationic compounds previously mentioned, other suitable cationic surfactants include the imidazolinium salts, such as 2-heptadecyl-l-methyl-l-[(2-stearoylamido) ethyl]-imidazolinium chloride; the corresponding methyl sulphate compound; 2-methyl-l-(2-hydroxyethyl)-1-benzyl imidazolinium chloride; 2-coco-l-(2-hydroxyethyl)-1-benzyl imidazolinium chloride;2-coco-l-(2-hydroxyethyl)-1-octadecenyl imidazolinium chloride; 2-heptadecenyl-l-(2-hydroxyethyl)-1-(4-chlorobutyl) imidazolinium chloride; and 2-heptadecyl-l-(hydroxyethyl)-1-octadecyl imidazolinium ethyl sulphate. Generally, the imidazolinium salts of preference will be halides (preferably chlorides) and lower alkylsulphates (alkosulphates).

Others of the mentioned quaternary ammonium salts and imidazolinium salts having fabric softening properties may also be employed in the present invention and various others of such compounds are described in U.S. Patent 4,000,077.
The fabric softening composition may also include other cationic fabric conditioning materials, such as cationic anti-static materials, and non-cationic fabric softening materials such as nonionic fabric softening materials. When nonionic fabric softening materials are included, the weight ratio of the cationic fabric softening material to the nonionic fabric softening material should be at least about 1:1, preferably at least about 3:1. The fabric softening composition may also include fatty acid.

The fabric conditioning compositions according to the invention may be in liquid, paste or granular solid form.
When in liquid form, the product may be in the form of a dilute rinse conditioner (containing up to about 10% by weight total active material) or in concentrated form.
Suitable formulations for concentrated rinse conditioners will include viscosity control agents such as are disclosed in GB 2 053 249 (Unilever Limited) where the compositions contain materials such as polyethylene glycol and US 4 149 978 (Goffinet assigned to Procter & Gamble Company) where the composition contain hydrocarbons. An alternative viscosity control agent is ianolin.

In dilute liquid fabric softening compositions the concentration of the fabric conditioning agent may be from about 0.5% to about 10% by weight, preferably from about 1.5%
to about 10% by weight. In concentrated liquid fabric softening compositions the concentration of the fabric softening agent may be from about 10% to about 60% by weight, preferably from about 10% to about 50% by weight.

When in liquid form, the fabric softening composition will contain, in addition to the fabric conditioning agent and the amphoteric polymer a liquid carrier such as an aqueous base C-59 217 7 l 25 which may consist only of water or of a mixture of water with other materials such as those referred to below.

The pH of the products of the invention may lie between about 3 and about 10, although products having a pH about 2 and about 3 are also possible. Suitable products can be prepared having a pH between about 6 and about 10. It is especially preferred if the fabric conditioner has pH from 5 to 8, measured at a 1% dilution of the product in water.
The compositions according to the invention may further include materials conventionally added to fabric conditioning compositions such as buffering agents, organic solvents, emulsifiers, colouring materials, bactericides, antioxidants, perfumes, perfume carriers, bleaches and hydrotropes.

When the fabric softening composition is in solid eg granular form, it may be prepared either by dry mixing the ingredients or by adsorbing the ingredients on a solid carrier, such as silica. Alternatively the composition may be formed in to a slurry which is subsequently spray dried.

The compositions of the present invention may be prepared by a variety of methods. One suitable method, in the case of dilute liquid fabric softening compositions, is to form a molten premix consisting of the fabric conditioning agent, water and optionally a solvent and adding the amphoteric polymer to this molten premix in the presence of sufficient water to give the desired dilution in the product.
The invention may be used to provide a softening effect in conjunction with any anionic detergent active or any detergent composition containing mixtures of anionic detergent active with other components, such as non-ionic detergents.

C_-o 5 9 217 712 5 The invention also comprises a method of rinse conditioning laundry items including the step of adding a fabric conditioning composition containing a cationic fabric softener and a amphoteric deposition polymer preferably having charged units a) and b) as herein described.

The invention will now be described by way of example only and with reference to the following non-limiting examples.
Examples of the invention will be illustrated by a number, comparative Examples will be illustrated by a letter.

Preoaration of ExamAles Composition were prepared by forming an aqueous dispersion of cationic active, adding the amphoteric polymer and adjusting the pH using sodium hydroxide.

Testina Methodoloav Anionic surfactant (weight as exemplified) was added to 1 litre of water in a Tergotometer 400 and agitated. The rinse conditioner composition according to the Example was added followed by 40g of pre-harshened fabric monitors.
Agitation was continued for 10 minutes, the cloths were removed, hand wrung and line-dried. Softening was assessed by trained panel by a qualitative comparison of the treatment fabrics. It is to be noted that as the tests are qualitative the results from the comparisons are grouped into tables according to the samples which were compared and the results in different tables are thus not comparable. Perfume intensity was again measured by a trained panel using a 0 (no perfume) to 5 (extremely strong) scale. Results are quoted as mean panel scales.

Examwles 1, 2 and A

Table 1 Examples were prepared according to the standard procedure.
Composition wt%
Examp~_e 1 Example 2 Example A
Arquad~' 2HT 5 5 5 Floc Aid 19 0.15 0 0.0 Floc Aid 34 0.0 0.15 0.0 NaOH 1 molar 5 5 solution Water ----- to 100 -----Arcxuad 2HT is dihardened tallow dimethyl ammonium chloride, ex Akzo"

Floc Aid 34 (ex National Starch") is a polymer mwt 180,000 :nade fr(Dm dimethyl diallyl ammonium chloride (DbiDAAC) and acrylic acid in a molar ratio of 1:1.5.

Floc aid 19 is a terpolymer mwt 140,000 made from DbIDAAC
acrylic acid and hydroxy propyl acrylate in a molar ratio of 3.4:2.3:1.

Ca..o 59 2177125 Table 2 Anionic Level Perfume Score Example 1 Example 2 Example A
No Anionic 1.6 1.3 1.1 20 ppm Anionic 1.5 1.4 -40 ppm Anionic 1.4 1.2 -60 ppm Anionic 0.9 1.0 0.3 The results clearly show a significant benefit in overcoming the adverse effects of the anionic in the presence of amphoteric deposition polymers.

Exambles 3 to 15 and B
Products were made as previously described containing 6.33 wt% Arquad 2HT 0.42wt%, tallow fatty acid, 0.2wt% amphoteric polymer and water to 100 wt%. The pH was adjusted to 6-8 using sodium hydroxide. Example B contained no amphoteric polymer. The ratio of DMDAAC to acrylic acid and the molecular weight of the amphoteric polymers is shown below.

Table 3 Example Acrylic Acid:DMDAAC mole Molecular Weight ratio 3 1:4 2650 4 1:1 2080 5 4:1 5290 6 1:4 45,000 7 1:1 54,000 8 4:1 227,000 9 1:4 103,000 10 1:1 200,000 11 4:1 460,000 12 3:1 43,000 13 3:1 111,000 14 2:1 48,000 15 2:1 125,000 Examples 6 and 9 showed excellent softening but were relatively unstable.

Softening of fabric was measured as previously described.
Softening results at 1:1.5 cationic : anionic ratio were measured and are illustrated below.

- - ------- ------C..,,- 5 9 Table 4 Example Preference Score*

*Scale 0 - 36 increasing softness Table 4 demonstrates that compositions containing amphoteric polymers with low molecular weights provide a preferential softening effect as compared with compositions which are free of such polymer.

Table 5 Example Preference Score (0-36) Table 6 Example Preference Score (0-36) - --- - -- ------ ------- ------C .__ ~ 9 Tables 5 and 6 demonstrate that, a preferential softening effect is achieved with a high DMDAAC : acrylic acid ratio.
Ratios with high acrylic acid to DMDAAC do not exhibit such pronounced softening effects. Acceptable softening is obtained over a wide range of polymer molecular weights.
Table 7 Example Preference Score (0-24) Table 8 Example Preference Score (0-24) Examnle 16 and Examvle C

Examples were prepared by adding the amphoteric polymer to the water, adjusting the pH to 12.5, then adding the cationic active to form a dispersion.

=

Table 9 Composition Wt.%

Example 16 Example C
HEQ* 5.03 5.91 Floc Aid 34 0.15 -NaOH 1 molar To pH 12.5 -Solution Water To 100%
* HEQ is 1.2 bis[hardened tallowoyloxy]-3-trimethylammonium propane chloride with fatty acid at 6:1 ratio (ex Hoechst).
[contains associated solvent 9.3% I.P.A & 8.9% glycerol % of total weight of cationic].
The examples were tested as stated above. The ratio of cationic to anionic are as exemplified below:

c>9 2177125 Table 10 Cationixmmirionic Softness Score (low = soft) Example 16 Example C
1:0 4.3 3.3 1:05 4.8 5.5 1:067 6.8 8.0 1:08 7.5 8.8 1:1 6.5 8.5 1:1.5 7.5 8.5 The softness scores in the above table are absolute softness scores in that each cloth was assessed by a trained panel and given a softness score based on a standard 2 to 14 scale.

Claims (9)

1. A fabric softening composition comprising more than 2%
of a cationic fabric softener and being substantially free from anionic detergent active, characterised in that the composition contains an amphoteric deposition polymer, said polymer having i) positively and negatively charged units ii) a molecular weight greater than 1,000 iii) a neutral unit or units having a molecular weight no greater than the combined molecular weight of the charged units.

2. The composition according to claim 1 in which the amphoteric deposition polymer has a structure in which said positively and negatively charged units comprise:
a) a positively charged unit derived from a monomer salt wherein the cation of the salt has a formula:
wherein R1 and R2 are independently selected from C1-C4 alkyl groups; R3 is a C1-C4 alkyl group or a C2-C4 alkenyl group and R4 is a C2-C4 alkenyl group, a C1-C4alkyl acrylate, a C1-C4 alkyl methacrylate, a C1-C4 alkyl methacrylamide, and a C1-C4 alkyl acrylamide;

b) a negatively charged unit having a carboxylate group derived from a monomer having a formula:
wherein R5, R6, R7 and R8 are independently selected from H1 or a C1-C4 alkyl group and a(CH2)n COOR8 in which n is an integer between 0 and 6.

3. The composition according to claim 2 in which a) the positively charged unit is derived from a monomer cation of the following formula R1 R2 N+ (CH2-CH=CH2)2 and b) the negatively charged unit comprises acrylate and/or methacrylate.

4. The composition according to claim 3 in which the neutral unit is an hydroxy propyl acrylate derivative.

5. The composition according to claim 1, 2 or 3 in which the amphoteric deposition polymer is present in an amount from 0.1 to 5% by weight.

6. The composition according to one of claims 1 to 5 in which the weight ratio of amphoteric deposition agent to cationic fabric softener lies in the range from 1:4 to 1:50.

7. The composition according to any one of claims 1 to 6 having a pH range from 5 to 8 measured at 1% dilution in water.

8. Use of an amphoteric deposition polymer having a molecular weight of at least 1000 in a fabric softening composition as a deposition aid, the polymer having i) positively and negatively charged units ii) a molecular weight greater than 1,000 iii) a neutral unit or units having a molecular weight no greater than the combined molecular weight of the charged units.

9. Use of the amphoteric deposition polymer according to claim 8 in which said positively and negatively charged units comprise;

a) a positively charged unit derived from a monomer salt wherein the cation of the salt has a formula:
wherein R1 and R2 are independently selected from C1-C4 alkyl groups; R3 is a C1-C4 alkyl group or a C2-C4 alkenyl group and R4 is a C2-C4 alkenyl group, a C1-C4 alkyl acrylate, a C1-C4 alkyl methacrylate, a C1-C4 alkyl methacrylamide, and a C1-C4 alkyl acrylamide;

b) a negatively charged unit having a carboxylate group derived from a monomer having a formula:
wherein R5, R6, R7 and R8 are independently selected from H1 or a C1-C4 alkyl group and a (CH2)n COOR8 in which n is an integer between 0 and 6.