EP2844349A1

EP2844349A1 - Polymers of trialkyl quaternary ammonium ethyl methacrylate salts as squeakiness enhancers in cleansing compositions

Info

Publication number: EP2844349A1
Application number: EP13716005.7A
Authority: EP
Inventors: Jean-Philippe Andre Roger Courtois; Junqi Ding; Chandra Sekhar PALLA-VENKATA; Jane Whittaker; Surajit Mukherjee; Rajendra Mohanlal Dave; Adam Peter Jarvis
Original assignee: Unilever PLC; Unilever NV
Current assignee: Unilever PLC; Unilever NV
Priority date: 2012-04-30
Filing date: 2013-04-16
Publication date: 2015-03-11
Also published as: JP2015521168A; GB201207443D0; WO2013164185A1; IN2014MN02091A; EA027978B1; CN104411364A; EA201491768A1

Abstract

A cleanser composition is provided which includes a homopolymer incorporating a monomer which is a trialkyl quaternary ammonium ethyl methacrylate salt, and a non-soap synthetic detergent. The composition exhibits a Squeakiness SQ1 value ranging from 5 to 100 grams as measured in an Acoustic Tribometer Tester.

Description

POLYMERS OF TRIALKYL QUATERNARY AMMONIUM ETHYL METHACRYLATE SALTS AS SQUEAKINESS ENHANCERS IN CLEANSING COMPOSITIONS

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to skin and hair cleansing compositions in toilet bar, body wash, liquid hand cleanser, shampoo and related products.

The Related Art Soap has been a mainstay active for cleansers. It is cheap and efficient. But it can be harsh on the skin. Synthetic surfactants have been introduced as replacements for soap. Some of these generate lather equivalent to that of soap and have the further benefit of being milder.

Often the skinfeel properties of a synthetic surfactant are quite different than that of soap. Indeed, generally as mildness increases, the deposition of the synthetic surfactant and other moisturizers increases. This forms a protective barrier to the stripping of natural oils and fats from the epidermis.

A majority of consumers in Japan, and many in other countries, dislike the oily feel of synthetic detergents. They consider moisturizing deposits as a sign of cleaning inefficiency. They need to be reassured of cleanliness by the traditional squeaky non-lubricated feel of soap. GB 2 104 091 A (Kao) discloses detergent compositions which include an amphoteric copolymer obtained by co-polymerizing an anionic vinyl monomer having a polymerizable unsaturated group with a cationic vinyl monomer also having a polymerizable unsaturated group. One of the latter is identified as dimethylaminoethylmethacrylate (DMAEMA) quaternized with methyl chloride.

U.S. Patent 3,547,950 (Johnson & Johnson) reveals water soluble acrylate polymers having skin adhering qualities. These polymers are prepared through the interpolymerization of dimethylaminoethylmethacrylate with esters of acrylic acid and/or esters of methacrylic acid, the amine group being quaternized. SUMMARY OF THE INVENTION

A cleanser composition is provided which includes:

(i) a homopolymer comprising monomer units formed from trialkyl

quaternary ammonium ethyl methacrylate salts;

(ii) a non-soap synthetic surfactant; and

wherein the composition exhibits a Squeakiness SQ1 value ranging from 5 to 100 grams as measured in an Acoustic Tribometer Tester.

DETAILED DESCRIPTION OF THE INVENTION

Now it has been found that homopolymers comprising monomer units of

trimethylammonium ethyl methacrylate salts can add squeakiness to the feel of non- soap-surfactant containing cleansing systems while not detracting from mildness. Squeakiness has been correlated by us to the output from an Acoustic Tribometer Tester. This instrument measures the friction coefficient of liquid systems during surfactant wash-off via a finger vibration device. After the first application and rinse off of sample to a skin area, the application should exhibit

a Squeakiness SQ1 value ranging from 5 to 100, usually between 10 and 90, particularly between 23 and 80, and especially between 30 and 80 grams as measured at 34 degrees C and an instrument speed of 17 mm/seconds.

The squeakiness enhancing homopolymers of the present invention are formed from monomer units having the structure (I):

wherein X^" is an anion selected from the group consisting of chloride, bromide, hydroxyl, sulphate, phosphate, methosulphate, carboxyl, citrate and tartrate. Most preferred as X^" is chloride.

Amount of the homopolymer may range from 0.01 to about 2%, preferably from 0.1 to about 1 %, more preferably from about 0.3 to about 1 %, and optimally from about 0.3 to about 0.8% by weight of the composition. Polymers of this invention are homopolymers. In certain embodiments, the homopolymers may be cross-linked with polyvinyl crosslinking monomers. The homopolymers may have a number average molecular weight ranging from 10,000 to 1 million, preferably from 10,000 to 800,000, more preferably from 15,000 to 500,000, and optimally from 20,000 to 300,000 Dalton. Most preferred is a homopolymer of structure (I) with a number average molecular weight ranging from about 30,000 to about 100,000 Dalton.

When the homopolymers are crosslinked, the crosslinking agents are not limited, and may be chosen for example from the polyolefinically unsaturated compounds commonly used for crosslinking polymers obtained by free-radical polymerization.

Examples of crosslinking agents that may be mentioned include divinylbenzene, diallyl ether, dipropylene glycol diallyl ether, polyglycol diallyl ethers, triethylene glycol divinyl ether, hydroquinone diallyl ether, ethylene glycol or tetraethylene glycol di(meth)acrylate, trimethylolpropane triacrylate, methylenebisacrylamide, methylenebismethacrylamide, triallylamine, triallyl cyanurate, diallyl maleate, tetraallylethylenediamine, tetraallyloxyethane,

trimethylolpropane diallyl ether, allyl (meth) acrylate, allylic ethers of alcohols of the sugar series, or other allylic or vinyl ethers of polyfunctional alcohols, and also the allylic esters of phosphoric and/or vinylphosphonic acid derivatives, or mixtures of these compounds.

According to one embodiment of the invention, the crosslinking agent is chosen from methylenebisacrylamide, allyl methacrylate and trimethylolpropane triacrylate (TMPTA). The degree of crosslinking is not limited, but generally may range from 0.01 mol % to 10 mol % and more particularly from 0.2 mol % to 2 mol % relative to the polymer. Another component of compositions disclosed herein is non-soap synthetic foaming surfactants. These may be selected from anionic, cationic, amphoteric and combination surfactants thereof. Amounts may range from 0.1 to about 30%, preferably from about 1 to about 20%, and optimally from about 3 to about 15% by weight of the composition.

Suitable amphoteric surfactants for use herein include, but are not limited to, derivatives of aliphatic quaternary ammonium, phosphonium, and sulfonium compounds, in which the aliphatic radicals can be straight or branched chain, and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one substituent contains an anionic group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate. Illustrative amphoterics are coco dimethyl carboxymethyl betaine, cocoamidopropyl betaine, cocobetaine, oleyl betaine, cetyl dimethyl carboxymethyl betaine, lauryl bis-(2-hydroxyethyl) carboxymethyl betaine, stearyl bis-(2-hydroxypropyl) carboxymethyl betaine, oleyl dimethyl gamma- carboxypropyl betaine, lauryl bis-(2-hydroxypropyl)alpha-carboxyethyl betaine, cocoamphoacetates, and mixtures thereof. The sulfobetaines may include stearyl dimethyl sulfopropyl betaine, lauryl dimethyl sulfoethyl betaine, lauryl bis-(2- hydroxyethyl) sulfopropyl betaine and mixtures thereof. Most preferred is cocoamidopropyl betaine.

The anionic surfactant may be, but is not limited to, C₈-C₂2 alkane sulfates, ether sulfates and sulfonates. Among the suitable sulfonates are primary C₈-C₂2 alkane sulfonate, primary C₈-C₂2 alkane disulfonate, C₈-C₂2 alkene sulfonate, C₈-C₂2 hydroxyalkane sulfonate or alkyl glyceryl ether sulfonate. Specific examples of anionic surfactants suitable for use herein include ammonium lauryl sulfate, ammonium laureth sulfate, triethylamine lauryl sulfate, triethylamine laureth sulfate, triethanolamine lauryl sulfate, triethanolamine laureth sulfate, monoethanolamine lauryl sulfate, monoethanolamine laureth sulfate,

diethanolamine lauryl sulfate, diethanolamine laureth sulfate, lauric monoglyceride sodium sulfate, sodium lauryl sulfate, sodium laureth sulfate, potassium laureth sulfate, sodium lauryl sarcosinate, sodium lauroyl sarcosinate, potassium lauryl sulfate, sodium trideceth sulfate, sodium methyl lauroyl taurate, sodium lauroyl isethionate, sodium laureth sulfosuccinate, sodium lauroyl sulfosuccinate, sodium tridecyl benzene sulfonate, sodium dodecyl benzene sulfonate and mixtures thereof.

An especially useful anionic surfactant is the ammonium or alkali metal salt of laureth sulfate having a degree of ethoxylation ranging from 0.5 to 1.5 moles, preferably from 0.8 to 1.2 moles, and optimally average of about 1 mole of ethoxylation per unit of hydrophobe (i.e. lauryl sulfate).

Of particular advantage as a synthetic anionic surfactant are the C₈-C₂2 acyl glycinate salts. Suitable glycinate salts include sodium cocoylglycinate, potassium cocoylglycinate, sodium lauroylglycinate, potassium lauroylglycinate, sodium myristoylglycinate, potassium myristoylglycinate, sodium palmitoylglycinate, potassium palmitoylglycinate, sodium stearoylglycinate, potassium

stearoylglycinate, ammonium cocoylglycinate and mixtures thereof. Cationic counterions to form the salt of an anionic surfactant may, for illustrative purposes only, be selected from sodium, potassium, ammonium, alkanolammonium and mixtures of these cations. Nonionic surfactants which may be used include the reaction products of compounds having a hydrophobic group and a reactive hydrogen atom.

Exemplative are alcohols, acids, amides or alkyl phenols reacted with alkylene oxides, especially ethylene oxide either alone or with propylene oxide. Specific nonionics are C₆-C₂2 alkyl phenols-ethylene oxide condensates, the condensation products of C₈-Ci8 aliphatic primary or secondary linear or branched alcohols with ethylene oxide, and products made by condensation of ethylene oxide with the reaction products of propylene oxide and ethylenediamine. Other nonionics include long chain tertiary amine oxides, long chain tertiary phosphine oxides and dialkyl sulphoxides. Also useful are the alkyl polysaccharides.

Surfactants should be chosen which will allow the compositions to have a SITA Foam Test Value ranging from 200 to 800, preferably from 300 to 700, and optimally between 400 and 600 ml. SITA Foam Tester R-2000 Model from the Future Digital Scientific Corp. is normally utilized for this evaluation. The

experimental protocol includes loading 10 g of product (no pre-dilution) into a measuring cylinder. Thereinto is added 250 ml water at 40-45° C. The foam volume is that recorded after stirring the sample for 30 seconds at 1000 rpm using a rotor. Final foam volume is obtained as the average of ten repeats of measuring the foam volume upon stirring the sample for the 30 seconds at 1000 rpm.

The C₈-C₂2 fatty acids optionally may also be included in compositions of this invention. Suitable fatty acids are lauric acid, myristic acid, palmitic, stearic, oleic, linoleic, behenic and acid combinations thereof. Particularly useful are the Ci₂-Ci₄ fatty acids such as lauric acid and myristic acid. Amounts of the fatty acid when present may range from 0.1 to 15%, preferably from 0.5 to 10%, and optimally from 1 to 5% by weight of the composition. Also useful components of the composition may be the C₈-C₂2 fatty alcohols.

Suitable fatty alcohols are lauryl alcohol, myristyl alcohol, cetearyl alcohol, stearyl alcohol, oleyl alcohol, linoleyl alcohol, behenyl alcohol and mixtures thereof.

Amounts of the fatty alcohol when present may range from 0.1 to 15%, preferably from 0.5 to 10%, and optimally from 1 to 5% by weight of the composition.

Water may be present in the compositions in amounts from 5 to 95%, preferably from 50 to 90%, and optimally from 65 to 85% by weight. Water soluble/dispersible polymers are an optional ingredient that may be included in the compositions. These polymers can be cationic, anionic, amphoteric or nonionic types. They are known to increase the viscosity and stability of liquid cleanser compositions, to enhance in-use and after-use skin sensory feels, and to enhance lather creaminess and lather stability. Amount of the polymers when present may range from 0.1 to 10% by weight of the composition.

Examples of water soluble/ or dispersible polymers include the carbohydrate gums such as cellulose gum, microcrystalline cellulose, cellulose gel, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium carboxymethylcellulose, methyl cellulose, ethyl cellulose, guar gum, gum karaya, gum tragacanth, gum arabic, gum acacia, gum agar, xanthan gum and mixtures thereof; modified and nonmodified starch granules and pregelatinized cold water soluble starch; emulsion polymers such as Aculyn® 28, Aculyn® 22 or Carbopol ©Aqua SF1 ; cationic polymer such as modified polysaccharides including cationic guar available from Rhodia under the trade name Jaguar C13S, Jaguar C14S, Jaguar C17, or Jaguar C16; cationic modified cellulose such as UCARE Polymer JR 30 or JR 40 from Amerchol; N- Hance® 3000, N-Hance® 3196, N-Hance® GPX 215 or N-Hance® GPX 196 from Hercules; synthetic cationic polymer such as Merquat® 100, Merquat® 280, Merquat® 281 and Merquat® 550 sold by Nalco; cationic starches such as

StaLok® 100, 200, 300 and 400 sold by Staley Inc.; cationic galactomannans such as Galactasol® 800 series by Henkel, Inc.; Quadrosoft® LM-200; and

Polyquaternium-24. Also suitable are high molecular weight polyethylene glycols such as Polyox® WSR-205 (PEG 14M), Polyox® WSR-N-60K (PEG 45), and Polyox@ WSR-301 (PEG 90 M).

Water-soluble skin benefit agents may optionally be formulated into the

compositions. A variety of water-soluble skin benefit agents can be used and the level can be from 0.1 to 50% but preferably from 1 to 30% by weight of the composition. These materials include, but are not limited to, polyhydroxy alcohols. Preferred water soluble skin benefit agents are glycerin, sorbitol and polyethylene glycol.

Water-insoluble skin benefit agents may also be formulated into the compositions as conditioners and moisturizers. Examples include silicone oils;

hydrocarbons such as liquid paraffins, petrolatum, microcrystalline wax, and mineral oil; and vegetable triglycerides such as sunflowerseed and cottonseed oils.

Preservatives can desirably be incorporated into the compositions to protect against the growth of potentially harmful microorganisms. Suitable traditional preservatives for compositions are alkyl esters of para-hydroxybenzoic acid. Other preservatives which have more recently come into use include hydantoin derivatives, propionate salts, and a variety of quaternary ammonium compounds. Particularly preferred preservatives are phenoxyethanol, methyl paraben, propyl paraben, imidazolidinyl urea, sodium dehydroacetate and benzyl alcohol. The preservatives should be selected having regard for the use of the composition and possible incompatabilities between the preservatives and other ingredients. Preservatives are preferably employed in amounts ranging from 0.01 % to 2% by weight of the composition.

A variety of other optional materials may be formulated into the compositions.

These may include: antimicrobials such as 2-hydroxy-4,2',4'-trichlorodiphenylether (triclosan), 2,6-dimethyl-4-hydroxychlorobenzene, and 3,4,4'-trichlorocarbanilide; scrub and exfoliating particles such as polyethylene and silica or alumina; cooling agents such as menthol; skin calming agents such as aloe vera; and colorants. In addition, the compositions of the invention may further include 0.5 to 10% by weight of sequestering agents, such as tetra sodium ethylenediaminetetraacetate (EDTA), EHDP or mixtures; opacifiers and pearlizers such as ethylene glycol distearate, titanium dioxide or Lytron 621 (Styrene/Acrylate copolymer); all of which are useful in enhancing the appearance or properties of the product.

The term "comprising" is meant not to be limiting to any subsequently stated elements but rather to encompass non-specified elements of major or minor functional importance. In other words the listed steps, elements or options need not be exhaustive. Whenever the words "including" or "having" are used, these terms are meant to be equivalent to "comprising" as defined above.

Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material ought to be understood as modified by the word "about".

It should be noted that in specifying any range of concentration or amount, any particular upper concentration can be associated with any particular lower concentration or amount. The following examples will more fully illustrate the embodiments of this invention. All parts, percentages and proportions referred to herein and in the appended claims are by weight unless otherwise illustrated.

EXAMPLES

Evaluations of squeakiness were performed by use of an Acoustic Tribometer Tester device as illustrated in the Figure.

Acoustic Tribometer Tester Instrumentation

The Figure is a close-up view of key aspects of the Acoustic Tribometer Tester instrument. These aspects include a sample stage (2), load cells (4, 6), a finger vibration device (8), an accelerometer (10), a support table (12), a position guider (14), a photosensor (16), hydrophone (18) and (not shown) a motor and limits which are at the end of position guider. The motor drives a rotary stage through a time- belt (not shown) which can damp the vibration noise from the motor rotation. The sample stage which is immersed into water is connected to the table by two load cells (Honeywell AL31 1AR, 1000g range) which can sense the vertical loads from DC to the frequency of 300Hz. Near the sample stage, a hydrophone (B&K 1803 hydrophone) is used to detect the underwater sound generated from the stationary sample substrate and the moving artificial finger. In the artificial finger, an accelerometer (PCB 352A24) is mounted just above water to detect the vibration of the artificial finger. An electromagnetic coil attached to the artificial finger makes it possible to apply finger load during rubbing of the substrate, and to lift up during reverse movement by reversing the voltage applied to the coil. The pivot in the artificial finger provides freedom to respond to the stick-slip generated during sliding through the test surface. The limit of the lift force constrains the length of the artificial finger, and therefore, constrains the water depth of the submerged sample stage. To avoid any deleterious effects of the surfactants in the water as they are washing away from the substrate, a large tank of water is used (50-53 liters). To render the data processing easier, a photosensor with the position guider is used to generate a "gate" signal where the "low to high" transition relates to the contact position at the right post in the sample stage and the "high to low" transition relates to the contact position at the left post. An electromagnetic relay system (USB- ERB24, Measurement Computing, Inc) is controlled by computer to switch between applying the finger loads (during the sliding) or lifting the finger (during the reverse movement). Further details on many aspects of the instrumentation can be found in EP1684631 B1 herein incorporated by reference.

Experimental Protocol After installing a set of substrates, the substrate and samples stages are immersed in water to soak. Prior to applying sample test composition onto the substrate, ten rubbing motions are made to establish a baseline for the blank substrate.

Thereafter the sample stage is removed from the water by lowering the water bath, and 0.25 gms of test composition is applied to the substrate (e.g. synthetic skin). The sample stage is then placed back into the water by raising the water tank. Next, the sample test compositions are rubbed 40 times against the surface with the artificial finger. The latter has a surface of the same substrate as on the sample stage. Water Hardness and Temperature

The rinsibility of test composition samples can depend on water hardness. To mimic different water conditions, calcium chloride and magnesium chloride are used to adjust the testing water. The ratio of calcium to magnesium is placed in the range from 3:1 to 4:1. Water temperature is adjusted by mixing the hot and cold water. The total amount of water in the tank for a test is around 14 gallons (about 53 liters). Swivelling Speed

The swivelling speed of the artificial finger can be fixed at 10 to 100 mm/s, but for the purposes of this invention is maintained at 17 mm/s. Friction Coefficient

The setup with two normal load cells creates a system which can measure normal force and friction coefficient. When the system goes to the squeaky region (stick-slip), the signal of load cell (4) and load (6) oscillates as the stick-slip generates the normal forces. The two load cells have the same phase in the oscillation and the sum of the two signals provides the amplitude of the stick-slip event.

The Squeakiness parameter SQ1 is based on the average deviation of the normal forces for 40 rubs of the first application. The normal force is the force applied through the artificial finger minus the dissipation on the friction. SQ1 is the average of all 40 rubs of the rinse while the swiveling speed is 17 mm/s. This is a good indication for the squeakiness. Samples

Polymers evaluated in cleanser compositions were prepared in the following manner and structures of reactants/catalyst/polymer are outlined below.

Statistical free radical polymerisations were carried out using a Chemspeed Swing robotic platform with the following general procedure.

For low molecular weight polymers - -20-50 K Dimethylaminoethyl methacrylate (DMAEMA) quat (40 ml of a 25% aqueous solution) was added to 4,4'-Azobis(4-cyanovaleric acid) (ACVA) (200 mg) with water (5 ml) and Isopropyl alcohol (IPA) (5 ml) to maintain polymerisations at 20% solids. The reaction mixture was heated and stirred at 75 ^QC for 4 hrs. The IPA was evaporated and residual monomer was removed by ultrafiltration. The poly( DMAEMA quat) was isolated via freeze drying as a white solid (9.0 g).

For high molecular weight polymers - -100-200 K DMAEMA quat (40 ml of a 25% aqueous solution) was added to 4,4'-Azobis(4- cyanovaleric acid) (ACVA) (100 mg) with water (10 ml) to maintain polymerisations at 20% solids. The reaction mixture was heated and stirred at 75 ^QC for 4 hrs. The polymer was purified by ultrafiltration. The poly(DMAEMA quat) was isolated via freeze drying as a white solid (9.0 g).

Molecular weight was measured with a Viscotek GPCmax 2001 triple-detection GPC. Chemical characterization was done using a Bruker Avance 400 MHz NMR with a samplejet autosampling robot. The proton nmr spectrum (D₂0) after purification showed no residual olefinic monomer peaks, with signals for the polymer at 4.5 ppm C(0)OCH2CH2; 3.82 ppm C(0)OCH2CH2; 3.25

N+(Me)3; 0.9-2.2 ppm polymer backbone.

A series of test compositions were prepared. The formulas of these test compositions and their Squeakiness SQ1 values are outlined in Table l-ll.

TABLE 1

squeakiness tests run at 17 mm/s, 34 degrees C. molecular weight of about 50,000 Dalton.

moles of ethoxylation averages about 1 mole.

TABLE I (continued)

¹ squeakiness tests run at 17 mm/s, 34 degrees C.

² molecular weight of about 50,000 Dalton.

³ moles of ethoxylation averages about 1 mole. TABLE II

squeakiness tests run at 17 mm/s, 34 degrees C. molecular weight of about 200,000 Dalton.

moles of ethoxylation averages about 1 mole TABLE II (continued)

moles of ethoxylation averages about 1 mole

The poly(trimethylammonium ethylmethacrylate chloride) homopolymer improved squeakiness response for compositions including as surfactant either cocoamidopropyl betaine, sodium laureth sulfate or sodium cocoyl glycinate. Best performance was seen with sodium laureth sulfate as the surfactant. For the latter, improvement in squeakiness ranged between about 54 and 68 grams in relation to a control without homopolymer. For instance, compare control Sample A versus Samples B, C, J and K. Useful, but of lesser effectiveness, was the homopolymer in conjunction with either cocoamidopropyl betaine or sodium cocoyl glycinate.

The above description is presented to enable a person skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the preferred embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Thus, this invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

Claims

A cleanser composition comprising:

(i) a homopolymer comprising monomer units formed from trialkyl quaternary ammonium ethyl methacrylate salts;

(ii) a non-soap synthetic surfactant; and

The composition according to claim 1 wherein the homopolymer has a number average molecular weight ranging from 10,000 to 800,000 Dalton.

The composition according to claim 1 wherein the homopolymer has a number average molecular weight ranging from 20,000 to 300,000 Dalton.

The composition according to claim 1 wherein the homopolymer has a number average molecular weight ranging from 30,000 to 100,000 Dalton.

5. The composition according to claim 1 wherein the monomer units have

structure (I):

(I)

wherein X^" is an anion selected from the group consisting of chloride, bromide, hydroxyl, sulphate, phosphate, methosulphate, carboxyl, citrate and tartrate.

The composition according to claim 1 wherein the homopolymer is crosslinked with a polyolefinically unsaturated compound.

The composition according to claim 1 wherein the non-soap surfactant is sodium laureth sulfate.

The composition according to claim 7 wherein the sodium laureth sulfate has an average of 1 mole of ethoxylation.

The composition according to claim 1 wherein the homopolymer is present in an amount from 0.01 to about 2% by weight.

The composition according to claim 1 wherein the homopolymer is present in an amount from 0.3 to about 1 % by weight.