GB1576762A

GB1576762A - Polymeric surface active agents

Info

Publication number: GB1576762A
Application number: GB31904/77A
Authority: GB
Original assignee: BF Goodrich Corp
Current assignee: Goodrich Corp
Priority date: 1976-08-02
Filing date: 1977-07-29
Publication date: 1980-10-15
Also published as: FR2360614A1; DE2733788A1; NL7708006A; BE857321A; SE7708676L; JPS5318490A

Description

(54) POLYMERIC SURFACE ACTIVE AGENTS (71) We, THE B. F. GOODRICH COMPANY, a corporation organized and existing under the laws of the State of New York, United States of America, of 277 Park Avenue, New York, State of New York 10017, United States of America, (assignee of VINCENT MARION RASICCI and IRA JOHN WESTERMAN), do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to polymeric surface active agents.

Polymeric surface active agents are known. However, polymeric surface active agents that have good emulsifying properties, while at the same time maintaining high surface tension when dissolved in water, are not readily available.

Unsaturated carboxylic acid and long chain ester copolymer water thickening agents are disclosed in U.S. Patent 3,915,592. These copolymers of a carboxylic acid monomer and one or more 10 to 30 carbon atoms alkyl acrylate esters serve as thickeners in solutions, even in the presence of substantial amounts of inorganic salts such as sodium chloride.

The polymers of this invention are made from at least two essential monomers, each in certain proportions, one being a monomeric olefinically-unsaturated carboxylic acid and the other being an acrylic ester having a long chain aliphatic group. Optionally, there is included in the monomeric mixture a copolymerizable sulfonic acid containing monomer.

According to the present invention there is provided a water soluble polymeric surface active agent having excellent emulsifying activity while unexpectedly contributing to high surface tension of the aqueous solution obtained by copolymerizing 20 to 60 weight percent of at least one acrylic ester monomer of the formula:

wherein R is an alkyl group containing 8 to 30 carbon atoms and R1 is hydrogen or alkyl containing 1 to 4 carbon atoms with 80 to 40 weight percent of an olefinically unsaturated carboxylic acid, or with 0 to 15 weight percent of a copolymerizable olefinically unsaturated sulfonic acid containing monomer and 25 to 80 weight percent of said carboxylic acid monomer, optionally in the presence of molecular weight modifiers as chain transfer or terminating agents, to provide copolymers having molecular weights of less than 10,000, and salts thereof.

The carboxylic monomers useful in the production of the polymers of this invention are the olefinically-unsaturated carboxylic acids containing at least one activated carbon-to-carbon olefinic double bond, and at least one carboxyl group, that is, an acid containing an olefinic double bond which readily functions in polymerization because of its presence in the monomer molecule either in the a- position with respect to a carboxyl group, thusly,

or as a part of a terminal methylene grouping thusly, CH2=C . In the p acids the close proximity of the strongly polar carboxyl group to the double-bonded carbon atoms has a strong activating influence rendering the substances containing this structure very readily polymerizable. Olefinically-unsaturated acids of this class include such widely divergent materials as the acrylic acids typified by acrylic acid itself, methacrylic acid, ethacrylic acid, a-chloroacrylic acid, a-cyano acrylic acid, A-methyl-acrylic acid (crotonic acid), a-phenyl acrylic acid, A-acryloxy propionic acid, sorbic acid, a-chloro sorbic acid, angelic acid, cinnamic acid, pchloro cinnamic acid, A-styryl acrylic acid (1 - carboxy - 4 - phenyl butadiene 1,3), itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid, maleic acid, fumaric acid, and tricarboxy ethylene. As used herein, the term "carboxylic acid" includes the polycarboxylic acids and those acid anhydrides, such as maleic anhydride. Maleic anhydride and the other acid anhydrides useful herein have the general structure

wherein R and R' are selected from hydrogen, halogen, cyanogen (-C-N), hydroxyl, lactam and lactone groups and alkyl, aryl, alkaryl, aralkyl, and cycloalkyl groups such as methyl, ethyl, propyl, octyl, decyl, phenyl, tolyl, xylyl, benzyl and cyclohexyl.

The preferred carboxylic monomers for use in this invention are the monoolefinic acrylic acids having the general structure

wherein R is a substituent selected from hydrogen, halogen, hydroxyl, lactone, lactam and the cyanogen (-C=-N) groups, monovalent alkyl radicals, monovalent aryl radicals, monovalent aralkyl radicals, monovalent- alkaryl radicals and monovalent cycloaliphatic radicals. Of this class, acrylic and alkacrylic as methacrylic acids are most preferred because of generally lower cost, ready availability, and ability to form superior polymers. Another particularly preferred carboxylic monomer is maleic anhydride.

The preferred acrylic ester monomers having long chain aliphatic groups are derivatives of acrylic acid represented by the formula:

wherein R is an alkyl group having from 8 to 30 carbon atoms, preferably 10 to 22 carbon atoms and R' is hydrogen or an alkyl group containing 1 to 3 carbon atoms.

Representative higher alkyl acrylic esters are decyl acrylate, lauryl acrylate, stearyl acrylate, behenyl acrylate and melissyl acrylate and the corresponding methacrylates. Mixtures of two or three or more long chain acrylic esters may be successfully polymerized with one of the carboxylic monomers. In addition to the acrylic ester monomer and the olefinically unsaturated carboxylic acid monomer the interpolymer may contain a vinylidene monomer, i.e., having at least one terminal H2C group so long as it has no deleterious effect on the desired properties of the copolymer.

Monomeric mixtures of the carboxylic monomer and the long chain acrylic ester monomer(s) preferably contain 95 to 50 weight percent carboxylic monomer and 5 to 50 weight percent acrylic ester monomer(s).

The copolymerizable olefinically unsaturated sulfonic acid containing comonomers preferably have at least one terminal ethylenic group and a sulfonic acid group. By the introduction of the sulfonic acid group into the polymer, it has been found that these polymeric emulsifiers are even more effective at very low pH, as 2 and below. Typical of monomers that will introduce a sulfonic acid group in the polymer include 2 - acrylamido - 2 - methyl propane sulfonic acid, ethylenesulfonic acid, alkylsulfonic acids, styrene sulfonic acid, 2 - sulfoethyl methacrylate and precursors thereof. These monomers are used in amounts from 0 to 15 weight percent, replacing part of the carboxylic acid monomers.

It should be understood that these polymeric emulsifier dispersants are substantially cross-link free, since they lose their effectiveness when cross-linked or gelled, or are of high molecular weight in which case they are substantially ineffective as surface active agents.

Low molecular weight copolymers of acrylic acid and long chain alkyl methacrylates, preferably also containing an olefinically unsaturated sulfonic acid monomer copolymerized therewith, in the salt form, neutralized with an inorganic or organic base to form a substantially water soluble material, are capable of initiating and supporting the emulsion polymerization of vinylidene monomers.

Vinylidene monomers, of course, are understood to include those monomers containing at least one terminal vinylidene group H2C. and are well known to those skilled in the art. The use of these surface active agents, particularly when they contain a sulfonic acid group, permit use in extremely low pH or aid such polymerization recipes. These emulsifier-dispersants have a number of other uses, for example, they may be used unexpectedly to product high surface tension latices which provide dried polymer deposits therefrom of improved water resistance, and improved substrate adhesion, when compared with conventional emulsifiers. These emulsifier dispersants may also be added as a post-polymerization latex stabilizer to contribute to higher surface tension latices.

According to the present invention there is also provided a method for the aqueous polymerization of vinylidene monomers with a free radical catalyst and a chain terminating agent, which comprises using, as emulsifying agent, an interpolymer of the invention.

The invention also provides an aqueous dispersion of a polymer of at least one vinylidene monomer containing an interpolymer of the invention.

The formulations of typical surface active agents of this invention are believed to have the general generic formula set forth below, wherein "a" is a long chain alkyl methacrylate such as isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate and is a number from about 30 to 50, "b" is acrylic or methacrylic acid and is a number from about 10 to 60, and "c" is from about 0 to 40 and is a sulfonic acid containing monomer including typically, 2 acrylamido - 2 - methyl propane sulfonic acid or sodium vinyl sulfonate.

The polymers of this invention are readily prepared by polymerization in an inert diluent having some solubilizing action on one or more of the monomeric ingredients, but preferably having little solvent action on the resultant polymer.

Polymerization in mass may be employed but is not preferred because of the difficulty in working up the solid polymeric masses obtained Polymerization in an aqueous medium containing a water-soluble free radical catalyst peroxygen is useful, the product being obtained either as a granular precipitate or as a highly swollen gel, either of which may be used directly or are easily further sub-divided and dried. Polymerization in an organic liquid which is a solvent for the monomers but a non-solvent for the polymer, or in a mixture of such solvents, in the presence of a solvent-soluble catalyst is most preferred because the product is usually obtained as a very fine friable and often fluffy precipitate which, after solvent removal, seldom requires grinding or other treatment before use. Suitable solvents for the latter method include benzene, xylene, tetralin, hexane, heptane, carbon tetrachloride, methyl chloride, ethyl chloride, bromo trichloro methane, dimethyl carbonate, diethyl carbonate, ethylene dichloride, and mixtures of these and other solvents.

The polymerizations are also conducted in the presence of a haloethane or halomethane, preferably containing at least four halogen atoms. Representative materials include for example, a fluoroethane, fluoromethane, chlorofluoromethane, bromofluoroethane, or preferably a chlorofluoroethane or chlorofluoromethane containing at least four halogen atoms including, for example, 1,1,2 - trichloro - 1,2,2 - trifluoroethane, trichlorofluoromethane, tetrafluoromethane, chlorotrifluoromethane, bromotrifluoromethane, 1 - chloro 1,1,2,2,2 - pentafluoroethane, dichlorodifluoromethane and 1,2 - difluoro - 1,1,2,2 - tetrachloroethane. The amounts of these materials used may be varied from the amount just sufficient to make a slurry of the reactants up to where there is a substantial excess of the chlorofluoroethane, as will be apparent to those skilled in the art. Preferred diluents are those which are solvents for the monomers but non-solvents for the polymers.

In order to obtain molecular weights of the polymer emulsifiers of an average less than 10,000, normally less than 5,000 average, in a more preferred range of 500 to 3,500, chain terminating or chain transfer agents are required. These are also referred to as molecular weight modifiers. These materials are generally of two types. First, those molecular weight modifiers such as the mercaptans containing from 6 to 20 carbon atoms, more preferably, 8 to 16 carbon atoms, including for example, dodecyl mercaptan, tertiary C12 mercaptan and the like alkyl mercaptans.

Other known chain transfer agents include halogenated materials, thiuram disulfide, dialkyl xanthogen disulfide, diaryl disulphides and substituted phosphines. The desired molecular weight may also be obtained by the use of solvents having chain terminating activity such as isopropanol and carbon tetrachloride. Combinations of these molecular weight modifiers are also contemplated. The amount of molecular weight modifying material used is an amount to provide a polymer molecular weight below 10,000 and this may readily be determined. Amounts from 0.1 to 10 weight percent based on the monomers, are contemplated, or even larger amounts of polymer modifying solvents. Preferred is 1 /, to 5 /,, alkyl mercaptan.

Polymerization in the diluent medium is carried out in the presence of a free radical catalyst in a closed vessel in an inert atmosphere and under autogenous pressure or artificially-induced pressure or in an open vessel under reflux at atmospheric pressure. Temperature of the polymerization may be varied from 0 C.

to 100"C., depending to a large degree on the molecular weight desired in the polymer. Polymerization under reflux at 50C to 900C. under atmospheric pressure using a free radical catalyst is generally effective in bringing a polymer yield of 75 to 100n e in less than 10 hours. Typical free radical forming catalysts include peroxygen compounds such as sodium, potassium and ammonium persulfates.

caprylyl peroxide, benzoyl peroxide, hydrogen peroxide, pelargonyl peroxide, cumene hydroperoxides, tertiary butyl diperphthalate, tertiary butyl perbenzoate, tertiary butyl peroxypivalate, sodium peracetate and sodium percarbonate as well as azo diisobutyryl nitrile, hereinafter referred to as azoisobutyronitrile and others well known to those skilled in the polymerization art. These polymers are neutralized with an inorganic or organic base. For example, with monovalent alkalis such as sodium, potassium, lithium or ammonium hydroxide or the carbonates and bicarbonates thereof, or mixtures of the same, and also amine bases having not more than one primary or secondary amino group. Polyvalent bases such as calcium hydroxide, magnesium and other IIA hydroxides may be used' Other organic bases such as triethanolamine, morpholine, dicyclohexylamine, dipropylamine, and tertiary amines for example triethylamine and the like may be used.

The present invention will now be further illustrated by way of the following examples: EXAMPLE I 40 weight parts of dodecyl methacrylate, 60 weight parts acrylic acid, 3.9 weight parts of tertiary dodecyl mercaptan, 0.35 weight part of caprylyl peroxide and 1125 weight parts of Freon 113, CF2CICFC12, were charged to a pressure vessel and heated at 650C. for 15 hours to substantially complete conversion to polymer.

"Freon" is a Trade Mark. The resulting polymer had an average number molecular weight based on end group sulfur analysis of 7,000+1,000. The copolymer was isolated from the Freon, dried and dissolved in distilled water containing 0.6% ammonium hydroxide to make a 1.0 /" solution. This poymeric emulsifier solution was then added in varying amounts to water and the surface tension of the solution measured in accordance with ASTM D1331 and compared to that of solutions of alkyl sulfide terminated polar oligomers (U.S. Patent No. 3,839,405) and sodium lauryl sulfate. The results obtained are as follows: TABLE I Lauryl Meth- Alkyl Sodium Conc. in acrylate/ Sulfide lauryl Water acrylic acid Oligomers sulfate dynes/cm dynes/cm dynes/cm 0.000 72.0 72.0 72.0 0.0025 72.0 61.4 47.3 0.0074 72.0 58.8 39.0 0.014 70.9 55.0 38.0 0.024 70.9 53.0 31.0 0.041 69.9 47.0 29.4 0.061 68.0 42.4 29.3 0.079 67.9 41.0 26.8 0.112 64.7 40.0 27.9 0.140 61.0 40.0 28.2 0.164 61.0 39.1 31.2 0.186 61.0 39.0 31.0 0.204 61.0 39.0 31.5 0.222 61.0 39.2 32.4 0.250 61.0 39.7 32.2 The surface tension of a water-mineral oil interface was also measured in accordance with ASTM procedure D971-50 and the results obtained were as follows: TABLE II Lauryl Meth- Alkyl Sodium acrylate/ Sulfide lauryl Conc. in acrylic acid Oligomers sulfate water dynes/cm. dynes/cm. dynes/cm.

0.00 37.2 37.2 37.2 0.0025 30.4 27.8 16.5 0.0074 22.1 10.5 12.4 0.014 25.3 3.2 3.9 0.024 25.9 2.8 4.7 0.041 17.8 2.8 4.9 0.061 18.7 2.8 4.6 0.097 17.9 2.2 5.9 0.127 15.8 2.9 5.1 EXAMPLE II In this polymerization the chain terminator, isopropanol, was used as the polymerization medium and 40 weight parts of dodecyl methacrylate, 60 weight parts of acrylic acid and 0.35 weight part of caprylyl peroxide were dissolved in 100 weight parts of isopropanol. This mixture was heated in an autoclave at 65"C. for 15 hours. Essentially complete conversion was obtained. To recover the solvent swollen solid, alternatively ammonia was bubbled through the solution and the solid was separated by centrifuging and drying.

EXAMPLE III Example II was repeated with 1.0 weight part of tertiary dodecyl mercaptan and similar results obtained.

EXAMPLE IV In another preparation, to an autoclave there was charged 40 weight parts of dodecyl methacrylate, 0.3 weight part of caprylyl peroxide and 250 weight parts of isopropanol. There was then added to this mixture a water solution of 15 weight parts of 2 - acrylylamidd - 2 - methyl propane sulfonic acid, 45 weight parts of acrylic acid and 35 weight parts of deionized water. The mixture was heated at 65"C. for 6 hours. The resulting solids was 28.9 /n and the conversion was greater than 97%. The polymer was isolated by bubbling ammonia through the solution, centrifuging and drying.

EXAMPLE V Three other copolymers were prepared in accordance with Example I using: (1)40 weight parts of lauryl methacrylate, 60 weight parts acrylic acid and 4.25 weight parts of t-dodecyl mercaptan. A 1% solution of the salt of this polymer in water had a Brookfield viscosity of 110 cps at 60 rpm with a &num;2 rotor; (2) Another copolymer was made in accordance with Example II in isopropanol with 40 weight parts lauryl methacrylate, 60 weight parts acrylic acid.

A 8.5 /" solution in water had a Brookfield viscosity of 75 cps at 60 rpm with a &num;1 rotor; (3) 40 weight parts lauryl methacrylate, 15 weight parts 2 - acrylamido - 2 methyl propane sulfonic acid and 45 weight parts acrylic acid reacted in isopropanol had a Brookfield viscosity of 7% total solids solution in water of the ammonium salt of 10 cps at 60 rpm with a #1 rotor; (4) 40 weight parts isodecyl methacrylate, 15 weight parts of 2 - acrylamido 2 - methyl propane sulfonic acid and 45 weight parts acrylic acid prepared in isopropanol had a Brookfield viscosity of a 10% water solution of the ammonium salt of 26 cps at 60 rpm with a #I rotor.

EXAMPLE VI A 1.5 /" solution of 2, 3, and 4 in Example V along with sodium lauryl sulfate solutions, a naphthalene dispersant (formaldehyde condensed naphthalene sulfonic acid) and polyacrylic acid were prepared and used to saturate bleached 11 mil flat paper which was then heat aged at 1050C. for 72 hours. The samples were tested during aging at 0, 6, 24, 48, and 72 hours by reading the change in light reflectance as measured on a photovolt meter model 610. The data are set forth in the data table below.

Heat Aging Light Reflectance Readings Hours 0 6 24 48 72 Control paper (Bleached Kraft) 87 86 86 86 85 Naphthalene dispersant 85 81 65 53 43 Emulsifier 2 88 81 76 74 71 Emulsifier 3 87 81 77 75 72 Emulsifier4 88 82 77 74 72 Sodium lauryl sulfate 88 86 81 74 62 Polyacrylic--Daxad* 30 87 75 69 67 66 * "Daxad" is a Trade Mark.

The outstanding resistance of ultraviolet discoloration of paper saturated with these emulsifiers compared to the naphthalene type dispersants is clearly demonstrated. These types of dispersants are widely used in latex polymerization recipes which are used in paper saturation for a variety of end use applications.

2-1/2"x4" paper samples were prepared for Fade-Ometer testing. "Fade-Ometer" is a Trade Mark. Samples were removed from the Fade-Ometer after 20, 40, 60 and 80 hours aging. Photovolt Reflectance was measured at each time interval and the sample replaced in the Fade-Ometer until the 80 hours of exposure to the UV light was completed. The Fade-Ometer reflectance values are tabulated in the Table below.

Ultra Violet Light Aging Reflectance Readings Hours 20 40 60 80 Control paper 82 82 82 82 Naphthalene dispersant 60 55 55 55 Emulsifier 2 82 82 82 82 3 82 82 82 82 4 82 82 82 82 EXAMPLE VII To demonstrate the use of the surface active agents in emulsion polymerizations, a series of reactions were run following the standard recipe set forth in the data table below. All constituents are in parts by weight per 100 parts of monomer. The polymerization was conducted at 70-80"C. for about 2 hours.

Distilled water 100 100 100 100 100 Sodium lauryl sulfate - 1.5 1 5 PolymerNo.4 1.5 - 1.5 I 5 Polymer No. 2 - - 1.5 Polymer No. 3 3 1 5 - 1.5 Ethyl acrylate 100 97 97 97 97 Acrylonitrile - 3 3 3 3 Ammonia persulfate 0.5 0.5 0.5 0.5 0.5 The following test results were obtained on the resulting latexes.

/O Coagulum 0.35 0 0.25 0.80 2.5 % Total Solids 48.2 48.7 47.2 47.9 46.9 Brookfield viscosity &commat;60rpm 85 cps 135 cps 40 cps 27cps 12 cps &commat;l2rpm 140 cps 300 cps 65 cps 35 cps 11 cps (K/c)o 4.519 0.2919 5.223 4.025 4.935 Particle Size A 4920A 1285 5282 4649 5137 Shear; Waring Blender Vis. at 60 rpm 1 mien. 105 cps Coagulate 37 cps 23 3 min. 780 Coagulate 175 105 92 5 min. 1260 - 640 540 420 The shear stability of the resulting latices was tested in a Waring blender at 17,500 rpm and the three latices made with the surface active agents of this invention all had better shear stability than the latex made with sodium lauryl sulfate. The surfactant made with 40 weight parts of isodecyl methacrylate, 45 weight parts of acrylic acid and 15 weight parts of 2 - acrylamido - 2 - methyl propane sulfonic acid had outstanding shear stability.

The polymeric surface active agents of this invention, and made in accordance therewith, preferably have a Brookfield viscosity in water substantially equivalent to that of a 1% solution of the ammonium salt of less than 300, preferably less than 200, centipoises at 60 rpm with a #2 rotor.

WHAT WE CLAIM IS: 1. An interpolymer containing 20 to 60 weight percent of at least one acrylic ester monomer of the formula

wherein R is an alkyl group containing 8 to 30 carbon atoms and R, is hydrogen or alkyl containing 1 to 4 carbon atoms and 40 to 80 weight percent of an olefinically

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

Ultra Violet Light Aging Reflectance Readings Hours 20 40 60 80 Control paper 82 82 82 82 Naphthalene dispersant 60 55 55 55 Emulsifier
2 82 82 82 82
3 82 82 82 82
4 82 82 82 82 EXAMPLE VII To demonstrate the use of the surface active agents in emulsion polymerizations, a series of reactions were run following the standard recipe set forth in the data table below. All constituents are in parts by weight per 100 parts of monomer. The polymerization was conducted at 70-80"C. for about 2 hours.

Distilled water 100 100 100 100 100 Sodium lauryl sulfate - 1.5 1 5 PolymerNo.4 1.5 - 1.5 I 5 Polymer No. 2 - - 1.5 Polymer No. 3 3 1 5 - 1.5 Ethyl acrylate 100 97 97 97 97 Acrylonitrile - 3 3 3 3 Ammonia persulfate 0.5 0.5 0.5 0.5 0.5 The following test results were obtained on the resulting latexes.

/O Coagulum 0.35 0 0.25 0.80 2.5 % Total Solids 48.2 48.7 47.2 47.9 46.9 Brookfield viscosity &commat;60rpm 85 cps 135 cps 40 cps 27cps 12 cps &commat;l2rpm 140 cps 300 cps 65 cps 35 cps 11 cps (K/c)o 4.519 0.2919 5.223 4.025 4.935 Particle Size A 4920A 1285 5282 4649 5137 Shear; Waring Blender Vis. at 60 rpm 1 mien. 105 cps Coagulate 37 cps 23

3 min. 780 Coagulate 175 105 92
5 min. 1260 - 640 540 420 The shear stability of the resulting latices was tested in a Waring blender at 17,500 rpm and the three latices made with the surface active agents of this invention all had better shear stability than the latex made with sodium lauryl sulfate. The surfactant made with 40 weight parts of isodecyl methacrylate, 45 weight parts of acrylic acid and 15 weight parts of 2 - acrylamido - 2 - methyl propane sulfonic acid had outstanding shear stability.

The polymeric surface active agents of this invention, and made in accordance therewith, preferably have a Brookfield viscosity in water substantially equivalent to that of a 1% solution of the ammonium salt of less than 300, preferably less than 200, centipoises at 60 rpm with a #2 rotor.

WHAT WE CLAIM IS: 1. An interpolymer containing 20 to 60 weight percent of at least one acrylic ester monomer of the formula

wherein R is an alkyl group containing 8 to 30 carbon atoms and R, is hydrogen or alkyl containing 1 to 4 carbon atoms and 40 to 80 weight percent of an olefinically

unsaturated carboxylic acid monomer, and having a molecular weight of less than 10,000.

2. An interpolymer as claimed in claim 1 wherein said interpolymer has a molecular weight below 5,000.

3. An interpolymer as claimed in claim 1 or claim 2 wherein R, is a hydrogen or methyl and R is an alkyl group containing 10 to 16 carbon atoms.

4. An interpolymer as claimed in any one of claims 1 to 3 wherein said olefinically unsaturated carboxylic acid monomer contains a terminal methylene grouping CHz=Cz 5. An interpolymer as claimed in claim 4 wherein said carboxylic monomer has the formula:

wherein R2 is hydrogen, halogen or a monovalent alkyl radical containing 1 to 4 carbon atoms.
6. An interpolymer as claimed in claim 5 wherein said carboxylic acid monomer is acrylic acid.
7. An interpolymer as claimed in claim 5 wherein, in said acrylate ester R2 is hydrogen or methyl and R is a monoalkyl containing 10 to 12 carbon atoms.
8. An interpolyiner as claimed in any one of claims 1 to 7 wherein the acrylic ester monomer is dodecyl or lauryl methacrylate.
9. An interpolymer as claimed in any one of claims 1 to 8 which is in the form of a water soluble salt.
10. An interpolymer as claimed in claim 9 which is in the form of a water soluble salt and wherein said salt is derived from an inorganic monovalent alkali metal, ammonia or an amine containing from 1 to 6 carbon atoms.
Il. An interpolymer as claimed in claim 10 which is in the form of an ammonia salt.
12. An interpolymer of 20 to 60 weight percent of an acrylic ester monomer of the formula

wherein R is an alkyl group containing 8 to 30 carbon atoms and R, is hydrogen or alkyl containing 1 to 4 carbon atoms and 25 to 80 weight percent of an olefinically unsaturated carboxylic acid monomer and 0 to 15 weight percent with an olefinically unsaturated sulfonic acid containing comonomer, having a molecular weight of less thari 10,000.
13. An interpolymer as claimed in claim 12 wherein said interpolymer has a molecular weight below 5,000.
14. An interpolymer as claimed in claim 12 or claim 13 wherein R, is a hydrogen or methyl and R is an alkyl group containing 10 to 16 carbon atoms.
15. An interpolymer as claimed in any one of claims 12 to 14 wherein said olefinically unsaturated carboxylic acid monomer contains a terminal methylene grouping CH2=C
16. An interpolymer as claimed in claim 15 wherein said carboxylic monomer has the formula:

wherein R2 is hydrogen, halogen or a monovalent alkyl radical containing I to 4 carbon atoms.
17. An interpolymer as claimed in claim 16 wherein said carboxylic acid monomer is acrylic acid.
18. An interpolymer as claimed in claim 16 wherein in said acrylate ester R2 is hydrogen or methyl and R is a monoalkyl containing 10 to 12 carbon atoms.
19. An interpolymer as claimed in any one of claims 13 to 18 wherein said acrylic ester monomer is dodecyl or lauryl methacrylate.
20. An interpolymer as claimed in any one of claims 12 to 19 wherein said sulfonic acid monomer is 2 - acrylamido - 2 - propane sulfonic acid.
21. An interpolymer as claimed in claim 20 wherein R is an alkyl group containing 10 to 14 carbon atoms and R, is hydrogen or methyl.
22. An interpolymer as claimed in any one of claims 12 to 21 which is in the form of a water soluble salt.
23. An interpolymer as claimed in any one of the preceding claims which additionally contains a vinylidene monomer having at least one terminal H2Cs group and which has no deleterious effect on the interpolymer.
24. A method for the aqueous emulsion polymerization of vinylidene monomers with a free radical catalyst and a chain terminating agent, which comprises using, as emulsifying agent, an interpolymer as claimed in any one of claims 1 to 23.
25. An aqueous dispersion of a polymer of at least one vinylidene monomer containing an interpolymer as claimed in any one of claims 1 to 23.
26. a method for the aqueous polymerization of vinylidene monomers with a free radical catalyst and a chain terminating agent, which comprises using, as emulsifying agent, an interpolymer as claimed in any one of claims 1 to 23.
27. An aqueous dispersion of a polymer of at least one vinylidene monomer containing an interpolymer as claimed in any one of claims 1 to 23.
28. An interpolymer as claimed in claim I or claim 12 and substantially as hereinbefore described with reference to any one of the Examples.
29. An aqueous dispersion as claimed in claim 24 or claim 27 and substantially as hereinbefore described with reference to any one of the Examples.
30. A method for the aqueous polymerization of vinylidene monomers as claimed in claim 24 or claim 26 and substantially as hereinbefore described with reference to any one of the Examples.
31. Vinylidene monomers whenever polymerized by a method as claimed in claim 24, 26 or 30.