DE2028291A1 - Composition and method for reducing static electricity in carpet - Google Patents

Description

1 BERLIN 33 8 MUNICH 27

Augu "U-Vlktorl" -Str "8 · 65 Dr.-Ιπα. HANS RUSCHKE PI «nz« nauerStraB »2

Pat. Dr. Ru.chk. 5 » _ucihl7 ιλμιαπ Pat. Attorney Aflular

Tif _ön! 0311 / H ₇ ⁷ JJi Dipl.-Ing. H A Z AG U LAR _{T. Phone!}

Telegram addrene t PATENTANWÄLTE Tel »gram addr ·« »·: Quadrature Berlin Quadrature Munich

S.G. Johnson & Son, Inc. Kacine, Wisconsin, V.St.A.

Composition and method of static electrical reduction Charges in carpet material

The present invention provides a composition for reduction the accumulation or storage of static electricity in carpet that is available an alkaline mixture of polymethacrylic acid and a carrier for such a mixture contains, the mixture being a has a pH of at least about 9 as a result of treatment of the acid with an alkali metal hydroxide.

The invention also provides a process for producing the polymethacrylic acid polymer available, according to which methacrylic acid is dissolved in water or aqueous lower alkanol, together with 1 to 5 % initiator and 20 to 60%, based on the weight of the initiator, reducing agent, and the methacrylic acid with the formation of polymethacrylic acid with a viscosity of the aqueous solution at 25 ⁰ O and 15 ^ solids · of not more than about 650 cP.

0 0-9 8 ß 5 / -2 0 Q Q

The formation of static electrical charges in textile products, is a well-known one especially in winter climates where the relative humidity is low Phenomenon. Such static electricity can range from an occasional disturbance to a very serious one dangerous problem in atmospheres containing explosive gas, vapor and / or dust mixtures. Though that Problem per se can occur with any [textile fiber at very low relative humidity, it is with natural and artificial fibers with poor moisture absorbency are serious. Therefore, the problem is often not with a cellulose material, such as cotton, acute, but with relatively hydrophobic fibers, such as nylon, Polyesters, the polyolefins and similar fibers, are present in a pronounced manner.

A number of methods that deal with the reduction of static electrical charges in fabrics are has been discussed extensively in the literature and various compositions have been made to address the problem to solve. Attempts have been made, particularly in textile treatment plants, to convert the fiber into a certain aqueous Exchange the solution so that a moisture-absorbing or other conductive film is on the surface of the Fiber settles. The difficulty with most of these formulations is that they are too easily removed can when the product made of the fibers is washed or cleaned, and the antistatic substance can can even be removed from the textile material by physical abrasion, »

• After another procedure that deals with this problem ', certain substances are crosslinked with the surface of the fiber · Although some of these processes are more or are less successful, the consumer who uses an article made of textile fibers and has a static one Charge finds no way to handle the

00988K / 209Q

Fibers or to cross-link them with fabrics. In addition, such treatments of the fiber surface are also frequent not a product that combines good antistatic properties with washing, cleaning or scrubbing resistance

A number of compositions are known which are derived from the Consumers can be applied to have some immunity to the build-up of static electricity to rent. Here again, however, is durability often a problem. In addition, many such treatments can affect the feel or other properties of the Affect the textile product so unfavorably that the treatments bring only a small practical advantage.

Although static electricity build-up is a problem with textiles in practically all areas of application, it is especially the case with carpet material, especially with widely used synthetic fabrics that have very little ability to retain moisture. To the treatment special requirements are placed on carpet material, because such a material inevitably subject to very severe wear and tear and accumulation of dirt and other contaminants is exposed. Many types of treatment that will be of greatest benefit in reducing the formation of static electricity are either extremely poor in durability or, more seriously, result in increased levels of dirt accumulation on carpet materials. Worse still, after the carpet is soiled, many anti-static finishes are often useful cannot be cleaned by conventional cleaning methods. That is, an extremely strong and wear-inducing Carpet cleaning must be done, if not all of the carpet, from the home, building, or office and to an institution for cleaning with special solvents must be brought according to special procedures.

009885/2090

Briefly, the present invention provides methods for reducing or eliminating the build-up of static electricity in carpet and other textile fibers, the method comprising treating textile fibers with an alkaline polymethacrylic acid mixture having a pH of at least about "9 containing alkali metal hydroxide , provides. the invention also provides compositions comprising such Polymethacrylsäuregemische together with excipients for depositing the ψ mixture to textile fibers. According to a particular embodiment of the invention the antistatic composition is present in an aerosol propellant shape that r be-for queme application to Carpet material and the like textile floor coverings is particularly suitable.

As will be further explained later, the treatment methods are distinguished by their ease of use, which can be attributed to the compositions. The compositions according to the invention and methods also result in very good ones when applied to carpet material. Durability. A particularly striking feature of the invention can be seen in that the carpets stain to a much lesser extent. In addition, if the carpet material is soiled, as inevitably happens with carpets, the ordinary Domestic and operational use are subject to dirt easily with ordinary cleaning agents, - in particular with anionic cleaning agents, with which deep-seated dirt and dirt from removed from a carpet.

The polymethacrylic acid used according to the invention is a relatively short-chain polymer. One such polymethacrylic acid is made using a bulk feed redox emulsion polymerization system (bulk charge redox emulsion polymerization system) and using an initiator and a reducing agent component to quickly produce a large

009885/2090

To form the number of free radicals and to produce the polymer with the required low molecular weight. It is known to the person skilled in the art that polymethacrylic acid can also contain proportions of other substances in the polymer chains. It is possible to incorporate smaller amounts of substances such as methyl methacrylate, but such material does not react significantly with the alkali metal hydroxides as described herein and should generally be limited to no more than about 10 % of the polymer weight. If such substances are present, more polymer must be used than is necessary when practically pure methacrylic acid is used. Accordingly, it is advantageous if the polymethacrylic acid is essentially a homopolymer.

The methacrylic acid starting material is practically free of substantial proportions of dimers and trimers. It is also advantageous when relatively low levels of inhibitors are present. Such is a content of hydroquinone monomethyl ether not much above 100ppm sufficient. Lower inhibitor levels are desirable, it is. but common for some inhibitor in the Methacrylic acid is present so that it can be handled and transported without it polymerizing in an uncontrolled manner.

The polymerization is advantageously carried out in aqueous systems or aqueous alkanol systems, lower allcanols with 2 b ± s 4 carbon atoms being advantageous. Water is a preferred reaction carrier. In general, the methacrylic acid makes up 10 to 20 % in the reaction carrier. Unless otherwise stated, all parts, proportions, percentages and ratios relate to that

> Weight.

Vie has been stated above, the reaction mixture tine initiator component and a reduction component contains · The

009885/2090

Initiators are peroxy compounds, advantageously inorganic peroxygen compounds. Preferred initiators are the alkali metal sulfates, in particular the alkali metal or ammonium persulfates such as sodium persulfate, potassium persulfate and the like. The amount of initiator used is preferably 1 to 5 % of the weight of the methacrylic acid.

Reducing compounds are added to accelerate the formation of polymer chains. Lower oxyacids from Sulfur are suitable reducing agents. So can alkali metal bisulfites, metabisulfites, hydrosulfites and thiosulfates as well organic sulfuroxy acids can also be used. A preferred reducing agent for practicing the invention is Alkali metal formaldehyde sulfoxylate, especially sodium formaldehyde sulfoxylate. The amount of reducing agent used is from 2o to 6o of the amount of initiator.

After the methacrylic acid has been dissolved in the reaction carrier, the temperature is preferably brought to a range of 50 to 95 ⁰ G. When the desired temperature is reached, the initiator and the reducing agent are added. It is particularly advantageous to carry out the reaction so that a polymethacrylic acid of relatively low viscosity and lower molecular weight is obtained. The polymethacrylic acid produced by the method for use in practicing the invention advantageously has a viscosity as a solution of less than 650 cP at 15% solids content and a temperature of 25 ⁰ O * The viscosity is advantageously no less than about 50 cP, so that the preferred range is 50 to 600 cP and a viscosity of about 600 cP gives excellent results.

The polymerization reaction can take place over a wide range of pressures to which both subatmospheric and superatmospheric pressures belong. If as a reaction carrier Water is used but results in the application of pressures,

009885/2090

_ 9 -

which are considerably below atmospheric pressure, to one undesirable surge at the desired reaction temperatures specified above. In general, it is beneficial to to apply atmospheric pressure to the reaction.

The polymerization reaction is carried out until the polymerization the methacrylic acid is practically perfected. This can be done by gas chromatographic analysis of a sample of the Reaction mixture can be determined. In general it is advantageous to that the free monomer content is less than about 0.005 / J, and this is a suitable criterion for the completeness of the implementation. The polymethacrylic acid can be used in the aqueous reaction vehicle in which it is produced had been used or can be dried ,, ^. 5 for example- by spray drying, so the pure hateri- '-: o to win. If an aqueous alkanol system has been used, the alcohol can be stripped off and the polymethacrylic acid in the then the present Jorni can be used.

The polymethacrylic acid thus produced is then treated with an alkali metal hydroxide treated so that a pH of at least about 9 is obtained. In general, the preferred one is directed pH range when carrying out the invention on the one hand according to the antistatic properties of the alkaline polymethacrylic acid and on the other hand, after the need for excessive alkalinity to avoid. In addition, a mode of operation outside of the desired range can also result in both wrongdoing the ability of the iPextil fibers to clean as well as an excessive accumulation of dirt and impurities in the Lead textile material. It is therefore advantageous that the pH range 9 to about 10.5. The preferred pH range for use herein is 9.6 * 0.2.

The, treatment with alkali metal hydroxide is advantageously carried out with an alkali metal having an atomic number of at least 11, because in most applications lithium is not one

009885/2090

so great in preventing an accumulation of static electrical charges like the higher alkali metals unfolded. From the standpoint of antistatic effectiveness Potassium, rubidium and cesium hydroxides lead to the best results. In many cases, however, it has been found .that agents with sodium hydroxide result in a somewhat better cleaning ability. According to this, although sodium, Potassium, rubidium and cesium hydroxides can be used, generally advantageously, sodium or potassium hydroxides for ~ to use the polymethacrylic acid treatment. It is especially beneficial to use potassium hydroxide.

Those skilled in the art can infer from the description of the invention that other alkali metal substances with high alkalinity are the same as those herein specifically described hydroxides are equivalent and can be provided according to the invention. As is well known many salts of the alkali metals with weak acids produce enough hydroxyl ions in aqueous solutions so that they are im are substantially equivalent to such hydroxides. The alkali metal carbonates are a particular example of such substances and bicarbonates.

The amount of alkaline polymethacrylic acid used in the compositions of the present invention for application to carpets ranges from about 3 to about 20 %. At lower concentrations, the excess impurity can be objectionable, and the viscosity at higher concentrations can create difficulties in obtaining uniform coatings on textile fibers at the desired levels of use.

When carrying out the process according to the invention, the alkaline polymethacrylic acid mixture is applied to the surface of the Textile material spread out so that a film or coating on the fiber arises »Although a substantial improvement is due to the distribution of a reticulated film the surfaces of the fibers, it is advantageous to

00988 5 / 2D90

when a substantially coherent film is formed on the fibers, in order to maximize surface conductivity and to ensure the smallest possible accumulation of static electrical charges. ■

The distribution of a larger amount of the polymethacrylic acid mixture helps ensure the continuity of the film · On the other hand, is the use of excessive amounts of polymethacrylic acid material unprofitable, unnecessarily expensive and can become abnormally strong at very high relative humidities Lead dirt pick-up. It has therefore been found that the best results are obtained when you at least get around

p 0.20 g of the alkaline polymer per 929 cm of carpet material applies. On the other hand, the use of essential results

2 more than 0.50 g of alkaline polymethacrylic acid per 929 cm Carpet material only has a small advantage in terms of further preventing static electricity. Accordingly, in practicing the invention, it is advantageous to have from about 0.20 to about 0.50 grams of alkaline polymethacrylic acid

ρ
to distribute 929 cm of carpet material in each case.

It can therefore be assumed that 28.35 S of alkaline poly-

2 methacrylic acid is sufficient to add about 9 ^ 29 m of carpet material treat. Less polymer is required for a fabric or for another smooth textile material, while something larger quantities sometimes for very coarse materials, such as a very deep pile carpet, required are.

The alkaline polymer can be applied to the carpet to be treated by wiping it over with a sponge, soaking it, sprinkling it or spraying it and appropriate measures are treated in order to achieve a relatively uniform distribution of the polymer. The compositions for application to carpets are advantageous aqueous and can contain the mixture that is obtained directly after the polymer treated with the hydroxide

009885/2090

- ίο -

has been delt. It is advantageous if the carrier material in which the polymer is distributed on the textile fibers, so is volatile as possible; However, the carrier must, of course, have to face the polymer and the textile fibers which the polymer is to be distributed, be inert. In addition, the carrier in the composition is intended for one application neither pose a fire hazard on carpets generate bad smelling or harmful odors or fumes. It is therefore advantageous if the composition a lower alkanol, preferably one, for applying the polymer to the surface of the textile fibers having 1 to 3 carbon atoms in the molecule. A preferred substance for use in the inventive Compositions is ethanol. In general, it is desirable that the composition contain up to about 20% alkanol.

It has been found that in some cases a better distribution can be achieved when the compositions according to the invention contain wetting agents or other agents that reduce the surface tension of the composition. Anionic marriage Surfactants are preferred in the compositions, although nonionic surfactants are also preferred can be used. Preferred surfactants include sulfonated alkyl aryl ethers such as Sodium dodecyldiphenyl ether disulfonate, alkyl sulfates, sulfonates and the like, ethoxylated alkanol sulfates, alkanols, alkyl phenols and the same. The preferred alkyl groups intended for such application are the higher alkyl groups, such as those obtained from triglycerides or synthesized from petroleum hydrocarbons. the The chain length then ranges from about 8 to about 22 carbon atoms. A preferred dispersant to use in carrying out the present invention is sodium dodecyldiphenyl ether disulfonate, which is sold under the trade name "Dowfax 2Al" «

Λ rt ö ο ö C j * ir \ η η

From the description of the invention it can be concluded that it can also be advantageous if other additives are included in the composition are included. Clarifiers, pigments or dyes (for carpet material with a special Paint) or other substances in the compositions according to the invention be incorporated. The use of clay ("Dispal") or colloidal silica ("Ludox") can be a Delay soiling under high humidity conditions.

Although the above compositions can be readily dispensed onto carpet or other substrates by spraying, sponge spreading, and the like, it has been found that it is particularly convenient to provide the compositions of the invention in admixture with a suitable propellant for packaging in pressurized aerosol containers . It is then easy for a consumer purchasing a product to use it and apply it directly to a carpet or other fabric on which the build-up of static electricity is to be prevented. Such preferred carpet treatment compositions contain, in addition to the alkaline I-olymethacrylic acid, the carrier and any other ingredient such as a surface active agent, a blowing agent. Such propellants include nitrogen oxides such as nitrogen oxides, low boiling hydrocarbons such as butane, isobutane and propane, and low boiling halogenated hydrocarbons such as dichlorodifluoromethane, trichlorofluoromethane, dichloro et rai'luoroethane, difluorotetrachloroethane and the like. Such blowing agents preferably comprise from about 2 to about 50 7 <> of the total aerosol formulation.

Am a simple way to measure antistatic ability or effects of the method according to the invention and the he-findun ^ sr-cLiü.ßon compositions make the effect of IolyraotiNiCr ^ acid materials on the specific super-

009885 /? 090 ' _{MD 0RIQ | NAL}

sheet resistance of a treated fiber or one of the treated fiber made use of fabric. So be after a. Test used to determine the accumulation of static Electricity is used, samples two inches square of acetate paste in a 50% aqueous solution Ethanol solution of an anionic cleaning agent, such as Example "Tide", pre-washed so that any antistatic agents or finishes are removed from the fabric. The pre-washed fabric is then dried and immersed in a solution * of the material to be tested. The excess Solution is allowed to drain for 30 seconds and any excess material left behind will be removed by absorption removed on absorbent cellulose. The fabric is then 30 minutes Long dried in air and ironed to its surface on a synthetic fabric temperature setting to smooth and remove any residual moisture.

The resistance measurement is carried out with a piece of plexiglass made of methyl methacrylate plastic, which contains two embedded parallel copper wires. The wires are 3.18 cm long and have a distance of 1.27 ^em each other. The weight is read on a megohm bridge (General Radio Type 544-B) j . A load of approximately 650 g is placed on the resistance plate to ensure reproducibility. The reading is taken twice on each side of the material, the first reading being taken on each side in a first position and the second reading being taken when the plate has been rotated at right angles to the first position. The average of four readings is reported as the resistance of the material per unit square.

Another advantage resulting from the invention is that after treatment with the neutralized Polymethacrylic acid according to the invention a carpet material a lot easier to clean than an untreated carpet. By

00988 5/2090

cleaning can improve the properties of the antistatic miotel are lost, but these properties are easily restored by simply re-treating according to the invention. "

After the tests described above, it is advantageous if a

9 Resistance is essentially not greater than 1 χ 10 ohms per unit square on the textile fibers in order to achieve antistatic electrical properties. Resistance values below this are of course also suitable, with lower values generally signifying greater freedom from the accumulation of static electrical charges. The tests performed here show that the present invention results in a nearly constant resistance to current passage within the range of 20 to 50 # relative humidity. while excessive surface moisture does not accumulate as the relative humidity is increased up to and above 50 % . This is important to avoid contamination at high relative humidities.

The following examples are given to illustrate embodiments of the invention as presently preferred in practicing the invention. The examples serve only to illustrate the invention, and the invention is not to be limited by these examples, with the exception of the features given in the accompanying claims.

example 1

15 ropes methacrylic acid are dissolved in 85 parts of water in a mixing vessel, and the mixture is heated to 65 ⁰ O. At this temperature, 1 mol / u (-2.65% by weight) ammonium persulphate initiator and 40 % sodium formaldehyde sulphoxylate

009885/2090.

("Formapon"), based on the weight of the initiator, entered into the reaction vessel. A rapid reaction takes place with the release of heat (temperature increase by about 16 ⁰ G), and the temperature of the reaction mixture is kept at 80-85 ⁰ C for one hour in order to obtain a polymethacrylic acid with low viscosity The reaction mixture is cooled to 25 ° C. and the polymer is added to a storage vessel.

The product is a clear, colorless liquid that contains 15-5% solids and has a viscosity of about 600 cP at 25 grams. The content of free fronomers is less than 0.005 ¹ P.

Di ^"v ^ so in a close obtained from 51 g Polymethacrylsäurelösuig is introduced into a mixing vessel, and 5i & g Kaliumhylroxidkügelchen be added so that a pH is obtained of about 9.6 ·

Example 2

An acetate fabric measuring two inches square was prewashed in a 50 'ethanol-aqueous solution of the anionic detergent "Tide" to remove any agents or finishes that may be present on the fabric. A solution of the 5 ^ ^ aliumhydroxid treated PoIymethacrylsäure which has been prepared according to the Example 1 is prepared, and the square l ^J robe from the Acetatstoff is immersed in the solution. The scoff is then removed from the solution and excess fluid is allowed to drain off. The saturated fabric is then placed on absorbent paper to dry and left overnight before the resistance test is carried out.

The fabric is then kept at a temperature of 23 ⁰ G and 20 % relative humidity overnight, and its resistance

009 885/2 0 90

is measured according to the method described above. Of the

The resistance of this sample is about 0.81 χ 1Cr Ohm. This " can be compared with a resistance of more than 2000 χ 10 ^ ohms for an untreated acetate fabric square.

Example 3 The following formulation is prepared:

Component 1 Quantity (parts)

Alkaline polymethacrylic acid - 15 »54 %

Solids (as prepared in Example 1) 51.02

Deionized water 31 »69

b5 / Λ-ges solid ivalium hydroxide

(to give pH 9 »6) 5» 80

Ethanol 11.09

"Dowfax" 2 Al-sulfonate (45 # solids) 0.40

The above formulation is under pressure with 3 'P of a hydrocarbon propellant mixture of isobutane and propane ("Propellant ¹ a 46) to achieve a vapor pressure of

2
'jy 22 kg / cm mixed.

This formulation is sprayed onto a carpet intended for domestic use so that approximately 0.4 g of polymer solids present per 929 cm of carpet and tested under relatively severe domestic winter conditions. It is found that by using this Formulation an arcing or sparking in a remarkable hate is prevented and that the treated carpet is easily washed with an anionic carpet or ceiling cleaner "ülorj" can be cleaned and its practical original color restored.

009885/2090

Example 4

Samples of the methacrylic acid prepared according to Example 1 are treated with lithium, sodium, potassium, rubidium and cesium hydroxides so that a pH of 9.6 is obtained. 5 % of a 2: 1 wipe of sodium laurysulfate and sodium lauroyl sarcosinate are added to each sample as a wetting agent. Samples of acetate fabric are washed in 5% solutions of each of the alkaline polymethacrylic acids and tested according to the procedure described in Example 2. After drying, each fabric treated with the respective solution is stored at 23 G and 20% relative humidity for 15 minutes and a different sample of each treated fabric is stored in this way overnight. The results of this test are given in Table I.

■ Table I

Resistance (x

Alkali metal after 1 ^ minutes over night Li 25.0 87.5 N / A 2.8 6.4 K 0.76 0.81 Rb 1.2 1.3 'Os 0.66 0.55 Example 5

A polymethacrylic acid is prepared as described in Example 1 and treated with sodium hydroxide, see above that a pH of 9.6 is obtained. 6 # liquid sodium dodecyl diphenyl ether disulfonate ("Dowfax" 2Al) are added and the mixture is placed on a new white nylon carpet with various Application strengths or grades sprayed. After this

009885/2090

Spraying the color of the carpet with a photoelectric Device measured.

The static electrical properties of the carpet are determined by shuffling on the carpet while your right index finger the test person is held in front of a "static viewfinder" ("Simco"), measured. After these initial measurements are made the samples are made of the white nylon carpet arranged on an area used in traffic where the carpet every day about 8CX) - is walked on up to 900 times. Of the Carpet is left on the used area for 5 days, after which repeated the measurements of color and static electricity will. After the color is measured, the carpet is cleaned with a commercially available carpet cleaner (das sold under the trade name "Glory"), cleaned, and the color is measured again. 4. Results of such Tests are reported in Table II. The higher the value for the "Color" reading in Table II, the higher the color is lighter.

Table II.

Lot of Static 'S ™ iL? 2i!? L «, ^ ei color after

(/ o ») Reading value» G ^ ffigegchtjkeit ^ m Heinigen

Max. 5 sec. 5.5 2.5 3.5 1.3 3.0 0.4 2.5 0.0 2.5 0.0

0.0 5.5 2.5 39.6

41.9 43.5

0.272 3.0 0.4 42 _t 6 44.3

0.408 2.5 0.0 42 _f 1 39.9

45.8 44.1

Claims

00 * 885/2090 om »*. M * om> ^

Claims (1)

- 18 Fat claims 1. Composition for reducing static electrical Charges in carpet material, characterized by an alkaline mixture of polymethacrylic acid and a carrier for such a mixture, the mixture having a pH of at least about 9 as a result of treatment of the acid with an alkali metal hydroxide. 2. Composition according to claim 1, characterized in that the alkali metal is sodium or potassium. 3. Composition according to claim 1 or 2, characterized in that that the pH is from 9 »2 to 10. 4. Composition according to claim 1, 2 or 3 * characterized in that that they also have a ^ close a surface-active Means to reduce the surface tension of the Contains composition. 5. Composition according to one of claims 1 to 4-, characterized characterized in that it also contains an amount of a propellant necessary to produce one for the discharge of the Composition from an aerosol container sufficient pressure. 6. Composition according to claim 5r, characterized in that . the propellant is a hydrocarbon of 2 to 4 carbon atoms in the liolekule .7 · Methods of reducing the accumulation of static electrical charges in carpet material, characterized in that that a film of the polymethacrylic acid gel according to one of the claims is applied to the surface of the textile fibers 1 to 6 applies. 009885/2090 8. The method according to claim 7> characterized in that the resistance of the textile fibers after application of the polymethacrylic acid mixture whom:
unit square. 10 methacrylic acid mixture less than 10 ohm per unit 9. The method according to claim 7 or 8, characterized in that that the polymethacrylic acid as a solution has a viscosity at 25 ° 0 and a polymethacrylic acid solids content of 15 ■ $> »does not exceed 650 cP. 10. The method according to claim 7 »8 or 9, characterized in that the ^ tightness of the polymethacrylic acid mixture _t based on the surface area of the textile material, about 0.2 to 2
about 0.5 g per 929 cm. 11. A process for the preparation of the polymethacrylic acid polymer used according to claim 1, characterized in that methacrylic acid is dissolved in water or an aqueous lower alkanol together with 1 to 5 % initiator and 20 to 60? O, based on the weight of the initiator, and the reducing agent methacrylic acid can no longer be on polymethacrylic acid having a viscosity of the aqueous solution at 25 ⁰ G and 15% solids of implement than about 650 cP. 12. The method according to claim 11, characterized in that the initiator is an alkali metal or organic persulfate. 13. The method according to claim 12, characterized in that the reducing agent is an oxyacid of sulfur. 14. The method of claim 11, 12 or I3, characterized in that the polymethacrylic acid product does not contain more than about 0.005 f> unreacted methacrylic acid. Dr.Ve/He. 009885/2090