MXPA96005582A - Cleaning concentrates and method for your preparation - Google Patents

Abstract

Disclosed is a process for preparing stable aqueous compositions of cleaning concentrates containing high concentrations of alkali and polymers useful as cleaning additives and scale inhibitors. Water-soluble polymer additives useful in preparing stable cleaning concentrates include the terpolymers of acrylic acid, maleic acid and vinyl acetate. The storage concentrates, stable in storage, are especially useful in providing cleaning formulations for automatic washing systems, such as in bottle washing and cleaning operations on the site.

Description

CONCENTRATES OF CLEANING AND METHOD FOR PREPARATION BACKGROUND The invention relates to an improved method for preparing stable, alkali-soluble cleaning compositions. More particularly, the invention relates to the selection of polymer additives for use in cleaning compositions which provide homogeneous, storage stable cleaning concentrates, which are useful in cleaning food stains from hard surfaces, such as those found in the operations of bottle washing and on-site cleaning (circulation type cleaning).

The current automation has influenced the operations of hotels and restaurants to such an extent that most of the eating utensils are cleaned in automatic washing procedures. The detergents used in these applications must have adequate cleaning properties and be provided in a physical form, which is easily handled and capable of being added to the cleaning operation in well-defined quantities. Powdered cleaning compositions are composed primarily of inorganic alkaline salts, such as phosphates, silicates and carbonates (known as "formers"). These detergents in powder have the disadvantage that they require the dissolution with water, in order to be added to the automatic washing operation, in a controlled manner, and in many cases the non-uniform addition occurs due to the cleaning components that dissolve more quickly, they are delivered first to the washing operation. Liquid cleaning formulations have been developed to remedy the disadvantages of powder formulations, but these liquid formulations are also limited in their cleaning efficiency, due to the large amounts of water required to dissolve the cleaning components; In addition, the incompatibility of some cleaning components further limits the preparation of a wide range of cleaning formulations in liquid form. Also, hardness ions (such as calcium, magnesium or barium), naturally present in the rinse water or the water used to prepare the concentrate or cleaning solutions, may further aggravate the cleaning problem, due to its tendency to react with the cleaning solution and return the non-active formation components in the cleaning solution. In order to counteract the effect of hardness ions, the cleaning compositions contain crusher-forming and inhibiting components (such as phosphonates) to prevent and minimize the build-up of hardness deposits (such as insoluble salts of phosphate). , carbonate and sulfate) or "crusts" on surfaces. The equipment used to manufacture, store or transport food products can be soiled by a variety of mechanisms, such as residues of degradation during cooking operations and residues from other food preparation and processing operations. On-site cleaning operations ("CIP") are used to clean a main portion of the equipment in modern dairy plants and also other food processing operations. CIP operations use a combination of chemical and physical effects to remove dirt from surfaces by transporting the cleaning solution to the dirty surface and combining the factors of time, temperature, detergency and strength. These CIP operations are traditionally used in pipe line systems, tanks and vats, heat exchangers, homogenizers and centrifugal machines.

Phosphorus-containing compounds (such as phosphates and phosphonates) have been used as trainers and inhibitors of selection fouling in previous aqueous cleaning solutions, but, due to the increased use of liquid detergents, where sodium tripolyphosphate has a solubility limited, and environmental problems increased with the use of phosphorus-containing trainers, alternative compositions have been investigated. However, with the decrease in the use of phosphate, the performance of cleaning compositions has also decreased.

JP 05-214397 discloses the use of 1 to 50% by weight of the carboxylated poly (ethylene glycols) as formers in solid cleaning formulations, containing up to 60% by weight of alkali metal hydroxide for automatic dish washing . The U.S. patent 3,887,480 discloses terpolymers of vinyl acetate, acrylic acid and maleic monomer, useful as ingredients in detergent formulations. U.S. Patent No. 5,191,048 discloses terpolymers of vinyl acetate, acrylic acid and maleic anhydride, useful in detergents and anti-fouling agents. The U.S. patent No. 5,273,675 discloses copolymers of acrylic acid and maleic anhydride, optionally containing an unsaturated carboxyl-free monomer, useful in cleaning concentrates containing a source of active chlorine.

Despite the large number of liquid cleaning compositions available as hard surface cleaners, there is still a need for liquid cleaning compositions that can be prepared in highly concentrated form, in the presence of high concentrations of alkali metal hydroxide, which are stable in storage and that they provide a satisfactory cleaning and inhibition of crusts during the washing of bottles, the cleaning of the dirty equipment of process of foods or the cleaning of utensils to eat and to drink.

The present invention seeks to overcome the problems of the prior art by providing an improved process for preparing stable, alkali-soluble cleaning compositions having satisfactory cleaning and crust inhibiting properties. EXHIBITION OF THE INVENTION A method for preparing an aqueous, stable, cleaning concentrate, which comprises combining, in an aqueous solution: (a) from 1 to 10 percent, based on the total weight of the cleaning concentrate, of a water soluble polymer , comprising, as polymerized units: (i) from 20 to 80 percent, based on the total weight of the polymer, of an unsaturated monocarboxylic acid monomer selected from one or more of the acrylic acid, methacrylic acid and its soluble salts in water; (ii) from 10 to 60 percent, based on the total weight of the polymer, of unsaturated dicarboxylic acid monomers; e (iii) from 10 to 50 percent, based on the total weight of the polymer, of unsaturated non-ionizable monomers, of one or more monomers of Formula I: CH (R1) = C (R2) OR3 (I) where : R1 is selected from hydrogen and -0-; R2 is selected from hydrogen and methyl; R3 is selected from -C (= 0) R4 and -C (= 0) OR5; R4 and R5 are independently selected from (C2-C3) alkyl; wherein, when R1 is -O-, R3 is -C (= 0) R4, and R and R3 are joined together to form a 5-membered ring with -O- of R1 replacing R4 at -C (= 0 ) R4; Y (b) from 15 to 50 percent, based on the total weight of the cleaning concentrate, of an alkali metal hydroxide, selected from one or more of the sodium hydroxide and the potassium hydroxide.

The present invention further provides an aqueous cleaning concentrate, comprising from 1 to 10 percent, based on the total weight of the cleaning concentrate, of a water-soluble polymer, as described above, of 15 to 50 percent, based on the total weight of the cleaning concentrate, of an alkali metal hydroxide, selected from one or more of sodium hydroxide and potassium hydroxide, and water. DETAILED DESCRIPTION Water soluble polymer additives, useful in the present invention, contain, as polymerized units, from 20 to 80 percent (%), preferably from 40 to 70% and more preferably from 50 to 70%, of a monomer of monocarboxylic acid, selected from one or more of the acrylic acid, methacrylic acid and its water soluble salts; from 10 to 60%, preferably from 10 to 40% and more preferably from 10 to 30%, of a dicarboxylic acid monomer; and from 10 to 50%, preferably from 10 to 30% and more preferably from 10 to 20%, of an unsaturated non-ionizable monomer, selected from one or more monomers of Formula I; all percentages are by weight and are based on the total weight of the water soluble polymer. Water-soluble salts of the polymer additives, for example, the alkali metal salts (such as sodium or potassium salts), and their ammonium or substituted ammonium salts, can also be used.In one embodiment of the invention, the water-soluble polymer comprises polymerized units of 50 to 70% unsaturated monocarboxylic acid monomer, 10 to 30% unsaturated dicarboxylic acid monomer and 10 to 30% unsaturated non-ionizable monomer. Preferred unsaturated nonionizable monomers include vinylene carbonate, vinyl acetate and vinyl propionate.

The "unsaturated dicarboxylic acid monomer", as used herein, refers to the monoethylenically unsaturated dicarboxylic acids, which contain from 4 to 10, preferably from 4 to 5, carbon atoms per molecule, and the anhydrides of the cis-acids. dicarboxylic. Monomers of dicarboxylic acid useful in the water-soluble polymer additives of the present invention include, for example, maleic acid, maleic anhydride, fumaric acid, a-methylene glutaric acid, itaconic acid, citraconic acid, esaconic acid, cyclohexenedicarboxylic acid , cis-1, 2, 3, 6-tetrahydrophthalic anhydride (also known as cis-4-cyclohexene-1,2-dicarboxylic anhydride) and its water soluble salts. Preferred unsaturated dicarboxylic acid monomers are maleic acid and maleic anhydride.

Examples of suitable unsaturated non-ionizable monomers of formula I are presented in Table I. The monomers of Formula I produce polymer additives containing latent hydroxyl groups. When the water soluble polymer additives are prepared by conventional polymerization techniques or formulated in aqueous concentrated cleaning compositions of the present invention, the ester or carbonate portions corresponding to R3 in Formula I (see Table I), they can hydrolyze, partially or completely, the corresponding hydroxyl derivatives. For example, R3 for compounds (1), (2) and (4) becomes -H in the hydrolysis (corresponding to a hydroxyl group attached to the backbone of the polymer additive, ie equivalent to a repeating unit of vinyl alcohol) and R1 and R3 for the compound (3) becomes -OH and -H, respectively (corresponding to adjacent hydroxyl groups in the backbone of the polymer additive). Table l The concentration of the water-soluble polymer additives (active ingredient) in the concentrated cleaning compositions of the present invention is from 1 to 10%, preferably from 1 to 5% and more preferably from 1 to 2% by weight of the concentrate. The concentration of the polymer additive in the concentrate composition is dependent on the amount of other components present that may have an impact on the desired performance characteristics and the compatibility of the concentrate. For example, if a phosphate-containing compound is present in the cleaning concentrate, the effective amount of the polymer additive, necessary to achieve the desired cleaning performance, may be less than if the phosphate-containing compound is not present. Substitution of the polymer additives of this invention for phosphorus-containing compounds (commonly used in cleaning compositions containing phosphate formers) should be considered when restricting the use of phosphates. The cleaning concentrate compositions of this invention are in the form of a liquid. As used herein, the "liquid" also refers to a gel or an aqueous paste. The compositions of the concentrate may include additional cleaning additives, of conventional type, well known to those skilled in the art, in amounts of conventional use. These conventional, optional, cleaning additives include, for example, formers, scavengers, water-soluble surfactants, anti-foaming agents, corrosion inhibitors, bleaching agents, stabilizers and anti-dye and opaque formers. . The amount of conventional, optional additives used will generally be from 0 to 40% and preferably from 1 to 20% by weight of the liquid composition of the cleaning concentrate.

This composition of the cleaning concentrate of this invention may contain formers, including, for example, inorganic forming salts, such as alkali metal polyphosphates (such as tripolyphosphates and pyrophosphates); ethylenediaminetetraacetic acid, nitrile acetate and alkali metal carbonates; water-soluble organic formers, such as citrates, polycarboxylates and carboxylates; and monomeric phosphonates (for example, amino-trismethylenephosphonic acid, 2-phosphonobutan-1, 2,4-tricarboxylic acid (PBTC), hydroxyethane-diphosphonic acid, diethylenetria ina-penta (methylene phosphonic) acid, ethylenediamine-tetraethylene phosphonic acid and their salts ), oligomeric and polymeric. The amount of the former used will generally be from 0 to 10%, preferably from 2 to 5%, by weight of the liquid cleaning concentrates.

The concentrated cleaning compositions of this invention may also contain an alkali metal silicate former at a concentration of 0 to 10% and preferably 3 to 5% by weight of the concentrate. The most preferred alkali metal silicates are sodium silicates. Although the alkali metal silicates are an optional component of the present invention, these silicates are beneficial when the corrosion inhibitor of the metal parts is convenient, since the compositions for the washing of highly alkaline dishes, which do not contain silicates, They can attack pots and containers of aluminum and other metal utensils.

Although optional, the concentrated cleaning compositions of this invention will generally contain a low-foaming soaking agent, generally in the form of a water-soluble surface active agent, for example, non-ionic and amphoteric surfactants, at a concentration from 0 to 2% and preferably from 0.5 to 1% by weight of the concentrate. Low-foaming soaking agents are preferred for concentrated compositions, since the foam can reduce the mechanical efficiency of the wash spraying or the rinse cycles of certain types of cleaning operations. Surfactants, water-soluble, low-foaming, anionic, non-ionic, zwitterionic (ambiguous), amphoteric, or combinations thereof, may be employed.

Optionally, the concentrated cleaning compositions of this invention may contain bleaching agents, for example chlorine-generating substances (such as sodium hypochlorite or chloroisocyanurates), peroxides, sulfites and perborates. Preferably, the concentrated compositions do not contain bleaching agents that generate chlorine. In addition, the concentrated cleaning compositions of this invention may contain segregants, such as sodium gluconate, at concentrations of 0 to 5% and preferably 1 to 2% by weight of the concentrate.

It has been found that the performance of the polymer additives used in the present invention does not depend on molecular weight, as long as the molecular weight of the polymer does not adversely affect its compatibility with the other components of the cleaning compositions. The weight average molecular weights (Mw) of the polymer additives of the present invention are typically from 1,000 to 100,000, preferably from 2,000 to 40,000, more preferably from 3,000 to 15,000 and even more preferably from 4,000 to 10,000, as measured by Aqueous gel permeation chromatography (GPC): Due to their solubility properties, polymer additives are useful in cleaning solutions that contain high levels of caustic substances. Many cleaning solutions, such as detergents for industrial bottle washing, on-site cleaning detergents and industrial and institutional detergents, contain high levels of caustic substances. Polymer additives are useful in these detergent compositions as scab inhibitors, dispersants, scavengers and anti-precipitants; however, many polymers of the prior art, such as poly (acrylic acid) and copolymers of acrylic acid and maleic acid, can not be used in these applications, because they are not soluble in highly caustic solutions.

In addition to providing the preparation of stable cleaning concentrates in storage, polymer additives, soluble in water, are useful in cleaning solutions prepared by other methods. For example, cleaning solutions can be prepared by combining, as separate components, the water soluble polymer additive, a 20 to 50 percent aqueous solution, an alkali metal hydroxide and water (sufficient for dilution), where the polymer, the alkali metal hydroxide solution and the water are added as separate streams in an in-line mixing system.

Optionally, an aqueous solution of conventional cleaning additives can also be added as a separate stream or used in place of the dilution water component, in the preparation of the cleaning solutions. The resulting cleaning solutions, obtained by diluting the concentrated cleaning compositions of the present invention or by other methods, such as those described above, typically contain: (a) from 0.005 to 0.4%, preferably from 0.01 to 0.1%, of the additive of the water soluble polymer; (b) from 0.1 to 3%, preferably from 0.2 to 2% and more preferably from 0.5 to 1.5%, from an alkali metal hydroxide, (c) water and, optionally, (d) from 0.001 to 2% additives Conventional cleaning, all concentrations are based on the total weight of the cleaning solution.

The use of polymeric additives, soluble in water, in cleaning solutions (diluted from concentrates or prepared by other methods), provides a method for cleaning hard surface materials, which involves contact with a dirty hard surface material with an effective amount of the cleaning solution containing the additive of the water-soluble polymer, until substantial removal of the dirt is achieved.

Aqueous solutions of the cleaning compositions of the present invention are effective for cleaning soiled surfaces over a wide range of wash water temperatures, typically from 5 to 952C, preferably from 30 to 802C and more preferably from 50 to 700C.

The concentrations of the alkali metal hydroxide (sodium hydroxide or potassium hydroxide) in the concentrated cleaning compositions of the present invention vary from 15 to 50%, preferably from 20 to 50% and more preferably from 25 to 40%, with based on the weight of the cleaning concentrate. A typical caustic composition of the cleaning concentrate contains 50 to 85% of the "caustic" substance or "soda lye" (such as 50% aqueous sodium hydroxide), 1 to 2% of the "polymer additive" and of the 0 to 40% of conventional additives, optional, cleaning, with the rest being water.

The concentrations of the alkali metal hydroxide in the cleaning concentrate can vary, depending on the application of end use. For example, the dishwashing cleaning concentrates typically contain 5 to 20% by weight of the alkali metal hydroxide, the on-site cleaning concentrates typically contain 10 to 30% by weight of the alkali metal hydroxide and the Bottle washing cleaning concentrates typically contain more than 35% by weight of the alkali metal hydroxide. The concentrated liquid cleaning compositions of the present invention will typically be prepared by dissolving the polymer additive and conventional, optional, cleaning additives in the desired amount of the caustic substance (with cooling) to deliver the homogeneous liquid cleaning concentrate. The cleaning concentrates are typically diluted with water to supply the actual cleaning solutions, used for contact with dirty materials on hard surfaces. Cleaning solutions are formed by diluting the cleaning concentrates in 0.1 to 5% by weight of the cleaning solution with water. The method of the present invention provides aqueous compositions, physically stable, of cleaning concentrates, which remain homogeneous during storage, that is, do not settle, separate or precipitate in different phases. The components of the liquid compositions of the cleaning concentrate and their relative proportions are selected so that they are compatible with each other, producing homogeneous liquid formulations. In general, the satisfactory stability or compatibility of the additives of the polymer of the present invention in the cleaning concentrates is indicated when a precipitation or phase separation has not occurred at room temperature, for at least 1 week, preferably for at least 4 weeks. weeks, more preferably for at least 8 weeks and even more preferably for at least 6 months, when the polymer additive is present at 1%, preferably 2%, by weight of the cleaning concentrate (containing from 35 to 40% in weight of sodium hydroxide).

The polymer additives, useful in the present invention, can be obtained by polymerization methods well known to those skilled in the art. Polymerizations can be conducted as co-loading, residual, i-continuous or continuous processes. When the polymerization is conducted as a residual process, most or all of the one or more unsaturated non-ionizable monomers and any of the unsaturated dicarboxylic acid monomers are present in the reactor and one or more monomers of unsaturated monocarboxylic acids are fed into the reactor. the reactor over time. In general, the charges are conducted for periods of time from 5 minutes to 5 hours, preferably from 30 minutes to 4 hours and more preferably from 1 hour to 3 hours.

When the polymerization is carried out as a co-loading process, the initiator and the monomers are introduced into the reaction mixture as separate charge streams that are added linearly with time, ie at constant regimes. The optional components of the reaction mixture, such as the neutralizing solutions, chain regulators and metals, may also be fed into the reaction mixture as separate charge streams or combined with one or more other charge streams. Preferably, the optional components are present in the waste. If desired, the currents can be staggered, so that one or more of the streams are completed before the others. If desired, a portion of the monocarboxylic acid and the non-ionizable monomers and the dicarboxylic acid monomers and / or a portion of the initiators can be added to the reactor before initiating addition of the monomers. The monomers can be fed to the reaction mixture as individual or combined charge streams in one or more charge streams. The processes by which the polymer additives of the present invention are prepared can be by aqueous, solvent or emulsion polymerization; preferably they are prepared by aqueous processes, i.e. substantially free of organic solvents. The water can be introduced into the reaction mixture initially as a separate charge stream, as the solvent for one or more of the other components of the reaction mixture or some combination thereof. In general, the polymerizations have final solids levels in the range of 20 to 80%, preferably 30 to 70%, by weight of the reaction mixture.

The temperature of the polymerization reaction will depend on the selection of the initiator and the target molecular weight. Generally, the temperature of the polymerizations up to the boiling point of the system, although the polymerization can be conducted under pressure, if higher temperatures are used. Generally, the temperature of the polymerization is from 25 to 1202C and preferably from 65 to 1102C. Suitable initiators for preparing the polymer additives of the present invention are any conventional water-soluble initiator. Suitable initiators that can be used are free radical thermal initiators, such as hydrogen peroxide, certain alkyl hydroperoxides, dialkyl peroxides, persulfates, peresters, percarbonates, ketone peroxides and azo initiators. Specific free radical initiators include, for example, hydrogen peroxide, tertiary butyl hydroperoxide, tertiary di-butyl peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, tertiary amyl hydroperoxide, and methyl ethyl ketone peroxide. . Free radical initiators are typically used in amounts of 0.5 to 25% based on the weight of the total monomer. The amount of the initiator used will vary according to the desired molecular weight of the resulting polymer and the relative amount of both the non-ionizable unsaturated monomers and the unsaturated dicarboxylic acid monomers. As the relative amount of the dicarboxylic acid monomer and the unsaturated non-ionizable monomer increases, or as the desired molecular weight of the polymer decreases, larger amounts of the initiator are preferred.

Water-soluble redox initiators can also be used. Redox initiators include, for example, sodium bisulfite, sodium sulfite, hypophosphites, phosphites, isoascorbic acid, sodium formaldehyde-sulfoxylate and hydroxylamines, used in conjunction with suitable oxidizing agents, such as free radical thermal initiators, before mentioned. Redox initiators are typically used in amounts of 0.05 to 10%, preferably 0.5 to 5%, based on the weight of the total monomer. Initiator combinations can also be used. A preferred method for obtaining the polymers of the present invention uses both a free radical initiator and a redox initiator. A particularly preferred combination of initiators is persulfate and peroxide. In one embodiment of the present invention, one or more water-soluble salts of metals can be used to promote polymerization and control the molecular weight of the resulting polymers. Water-soluble salts of metals, such as the copper, iron, cobalt and manganese salts, are typically used at levels of 1 to 200 parts per million (ppm), preferably 3 to 100 ppm, of the metal ions, based on the weight of the polymerizable monomers. Preferred metal salts are the copper and iron salts, which include all inorganic and organic compounds that will generate copper or iron ions in an aqueous solution. Suitable salts include, for example, sulfates, nitrates, chlorides, acetates and gluconates.

It is generally convenient to control the pH of the monomer mixture of the polymerization, using a redox initiator or a thermal initiator. The pH of the monomer mixture of the polymerization can be controlled by a regulatory system or by the addition of a suitable acid or base. The pH of the system can be adjusted to suit the selection of the redox system by the addition of an appropriate acid or base, if necessary.

In processes where all or some of the monomers are gradually added to the reaction mixture, the pH of this reaction mixture can also be controlled by the gradual addition of a neutralizer. Examples of suitable neutralizers include, for example, sodium, potassium or ammonium hydroxides, and amines, such as triethanolamine and ammonia water. These neutralizers are used as aqueous solutions and can be added gradually to the reaction mixture as separate charge streams or as part of one of the other charge streams. Typical levels of neutralizers are from 20 to 95% equivalents of the base, preferably from 20 to 80% equivalents of the base, with respect to the total acid functionality of the monomer components. The polymerization processes for the preparation of the polymer additives used in the present invention generally result in a good conversion of the monomers to the polymer product. However, if the residual levels of monomers in the polymer blend are inconveniently high for a particular application, these levels can be reduced by any of several techniques. A common method for reducing the level of the residual monomer in a polymer mixture is the addition, after polymerization, of one or more initiators or reducing agents, to assist in the purification of the unreacted monomer. Preferably, any post-polymerization addition of initiators or reducing agents is conducted at or below the polymerization temperature. Suitable initiators and reducing agents for reducing the residual content of monomers are well known to those skilled in the art. In general, any of the initiators suitable for the polymerization are also suitable for reducing the residual content of the monomer of the polymer mixture. The level of initiators or reducing agents added as a means to reduce the residual monomer content should be as low as possible to minimize contamination of the product. In general, the level of the initiator or reducing agent added to reduce the residual monomer content will be in the range of 0.1 to 2.0 mole%, preferably 0.5 to 1.0 mole%, based on the total amount (moles) of the polymerizable monomer.

The polymers of the present invention are soluble in water. This solubility in water is affected by the molecular weight of the polymers and the relative amounts and hydrophilicity of the monomer components incorporated in the polymer. If desired, chain regulators or chain transfer agents can be employed to help control the molecular weight of the polymers. Any conventional chain-regulator or chain transfer agent, soluble in water, can be used. Suitable chain regulators include, for example, mercaptans, hypophosphites, phosphites, alcohols and bisulfites. If used, mercaptans (such as 2-mercaptoethanol), bisulfites (such as sodium metabisulfite) or hypophosphites are preferred.

Some embodiments of the invention are described in detail in the following examples. All ratios, parts and percentages (%) are expressed by weight, unless otherwise specified, and all reagents used are of good commercial quality, unless otherwise specified.

EXAMPLE 1 To a 1-liter, 4-neck, round-bottomed flask equipped with a mechanical stirrer, reflux condenser, thermal pair and inlets for the gradual addition of monomers, initiator solution and solution of the transfer agent. chain, 110.80 grams of deionized water, 14.35 grams of maleic anhydride, 0.33 grams of sodium metabisulfite and 3.69 grams of a metal promoter solution of 0.15% ferrous sulfate in deionized water were added to form a reaction mixture. This reaction mixture was heated to 72 ° C, after which the following four separate charges were started at the same time: (1) 71.76 grams of glacial acrylic acid, (2) 57.41 grams of vinyl acetate, (3) a solution of load of sodium metabisulfite of 12.82 grams of sodium metabisulfite and 56.51 grams of deionized water, (4) an initiator solution of 8.61 grams of sodium persulfate and 50.93 grams of deionized water. The loading solution of sodium metabisulfite was fed for 75 minutes and glacial acrylic acid, vinyl acetate and initiator solutions were fed, for 90 minutes. Once the additions were complete, the reaction mixture was kept at 72 ° C for 15 minutes and then 0.10 grams of sodium persulfate in 1.00 gram of water was added. The reaction mixture was kept at 72 ° C for an additional 15 minutes, and then 0.10 grams of sodium persulfate in 1.00 gram of water was added. The reaction mixture was maintained at 72 ° C for an additional 15 minutes and then cooled to room temperature. This reaction mixture was neutralized to a pH of 7.0 by the slow addition of 99.0 grams of 50% sodium hydroxide, keeping the temperature below 25ac.

The resulting polymer solution had a pH of 7.0 and a solids content of 41.94%. The weight average molecular weight (Mw) was 4,010 and the number average molecular weight (Mn) was 3,220. The levels of acrylic acid and residual maleic acid were both not detectable (limit of detection = 66 ppm). The residual level of vinyl acetate was 586 ppm.

Example 2 To a 1-liter, 4-necked, round-bottomed flask equipped with a mechanical stirrer, reflux condenser, thermal couple and inlets for the gradual addition of monomers, initiator solution and solution of the transfer agent. chain, 110.80 grams of deionized water, 16.15 grams of maleic anhydride, 0.18 grams of sodium metabisulfite and 3.69 grams of a metal promoter solution of 0.15% ferrous sulfate in deionized water were added to form a reaction mixture. This reaction mixture was heated to 72 c, after which the following four separate charges were started at the same time: (1) 100.46 grams of glacial acrylic acid, (2) 26.91 grams of vinyl acetate, (3) a sodium metabisulfite loading solution of 7.14 grams of sodium metabisulfite and 56.51 grams of deionized water, (4) an initiator solution of 8.61 grams of sodium persulfate and 50.93 grams of deionized water. The loading solution of sodium metabisulfite was fed for 75 minutes and glacial acrylic acid, vinyl acetate and initiator solutions were fed, for 90 minutes. Once the additions were complete, the reaction mixture was kept at 72 ° C for 15 minutes and then 0.05 grams of sodium persulfate in 1.00 gram of water was added. The reaction mixture was maintained at 72 ° C for an additional 15 minutes, and then 0.05 grams of sodium persulfate in 1.00 gram of water was added. The reaction mixture was maintained at 72 ° C for an additional 15 minutes and then cooled to room temperature. This reaction mixture was neutralized to a pH of 7.0 by the slow addition of 136.10 grams of 50% sodium hydroxide, keeping the temperature below 25ac.

The resulting polymer solution had a pH of 7.0 and a solids content of 39.38%. The weight average molecular weight (Mw) was 4,900 and the number average molecular weight (Mn) was 3,960. The levels of acrylic acid and residual maleic acid were both not detectable (limit of detection = 65.4 ppm). The residual level of vinyl acetate was not detectable (limit of detection = 10 ppm).

Examples 3 to 23 Alkali Solubility and Stability in the Storage of Cleaning Concentrates The polymer additives of the present invention were tested for alkali solubility and storage stability by the following method: a glass jar 118 milliliters were added 2.0 grams of the solid polymer, followed by the addition of water, so that the total weight was 20.00 grams. Then, to this solution, in an ice-water bath, 80.00 grams of 50% sodium hydroxide were added, with stirring, so that the temperature did not exceed 25ac. The solution was left to rest, before making observations.

The alkali solubility and satisfactory storage stability of the polymer additives of the present invention is indicated when there is no precipitation or phase separation at room temperature for at least 1 week (see table 2). The solubility data in the Table are based on the polymer additives tested at 1% by weight in 80% of a caustic substance (50% sodium hydroxide). Certain polymer additives were also tested for extended periods of time; these data are indicated as overwritten in the column "Solubility in Alkali", which designates the minimum number of weeks (or 7) that they are soluble at the 1% level. The abbreviations used in the table are listed below with the corresponding descriptions; the polymer additive compositions are designated by the relative proportions of acrylic acid, maleic acid and vinyl acetate. Examples 3, 4 and 9 represent comparative compositions (comp.) Of polymer additives, which do not contain the unsaturated non-ionizable monomer. Polymer additives containing 50 to 70% AA, 11 to 31% MALAC and 11 to 31% HEA were also evaluated for solubility in high caustic concentrates and were found to be insoluble under the conditions described above. AA = acrylic acid MALAC = maleic acid VAc = vinyl acetate HEA = hydroxyethyl acrylate NA = not analyzed + = soluble in caustic - = insoluble in caustic.

Table 2 Example 24 Inhibition of Scale - Test Method The polymer additives of the present invention were evaluated in scale inhibition (anti-stain efficiency) under conditions that simulate temperature and caustic concentrations (0.5% sodium hydroxide at 60ac), typically found in bottle washing and CIP operations, determining the amount of carbonate scale formed on the microscope slides, after storage overnight at 60ac. Aqueous test solutions containing the required amount of caustic (sodium hydroxide) and 200 ppm (0.02% by weight) of the polymer additive were prepared; the hardness of the water was equivalent to 400 ppm (as CaCC > 3). The microscope slides were placed in laboratory vessels containing the test solutions, and the vessels and their contents were maintained at 60 c overnight (approximately 14 to 18 hours). The slides were then removed from the laboratory vessels and evaluated for cleanliness: "0" represents "no carbonate inlays" (clean slides) and "5" represents "dense carbonate inlays" (slides completely covered by a white layer) of carbonate). The anti-stain values are summarized in Table 2. Anti-stain values of 0.5 are typical for conventional phosphonate scale inhibitors, used alone (without polymer additives) at 100 ppm, in the presence of 0.5% hydroxide. sodium. Generally, a satisfactory scale inhibition is indicated by anti-stain values of less than or equal to 2-3, preferably less than or equal to 1 and more preferably less than or equal to 0.5.

Claims (15)

1. A method for preparing an aqueous, stable, cleaning concentrate, which comprises combining, in an aqueous solution: (a) f1 to 10 percent, based on the total weight of the cleaning concentrate, of a water-soluble polymer , comprising, as polymerized units: (i) f20 to 80 percent, based on the total weight of the polymer, of an unsaturated monocarboxylic acid monomer selected fone or more of the acrylic acid, methacrylic acid and its soluble salts in water; (ii) f10 to 60 percent, based on the total weight of the polymer, of unsaturated dicarboxylic acid monomers; e (iii) f10 to 50 percent, based on the total weight of the polymer, of unsaturated non-ionizable monomers, of one or more monomers of Formula I: CH (R1) = C (R2) OR3 (I) where : R1 is selected fhydrogen and -0-; R2 is selected fhydrogen and methyl; R3 is selected f-C (= 0) R4 and -C (= 0) OR5; R4 and R5 are independently selected f(C2-C3) alkyl; in that, when R1 is -O-, R3 is -C (= 0) R4, and R1 and R3 are joined together to form a 5-membered ring with -O- of R1 replacing R4 in -C (= 0) R4; and (b) f15 to 50 percent, based on the total weight of the cleaning concentrate, of an alkali metal hydroxide, selected fone or more of the sodium hydroxide and the potassium hydroxide.

2. The method according to claim 1, wherein the water-soluble polymer comprises, as polymerized units, f50 to 70 percent of the unsaturated monocarboxylic acid monomer, f10 to 30 percent of the unsaturated dicarboxylic acid monomer and f10 to 20 weight percent of the unsaturated non-ionizable monomer.

3. The method according to claim 1, wherein the unsaturated non-ionizable monomer is selected fone or more of vinylene carbonate, vinyl acetate and vinyl propionate.

4. The method according to claim 1, comprising combining f25 to 40 percent, based on the total weight of the cleaning concentrate, of the alkali metal hydroxide in the aqueous solution.

The method according to claim 1, comprising f1 to 2 percent, based on the total weight of the cleaning concentrate, of the water soluble polymer in the aqueous solution.

6. The method according to claim 1, further comprising f1 to 20 percent, based on the total weight of the cleaning concentrate, of conventional cleaning additives, selected fone or more of forming agents, segregates, surfactants soluble in water, anti-foaming agents, corrosion inhibitors, bleaching agents, stabilizing and anti-staining agents, and opacifying agents.

7. An aqueous cleaning concentrate, which comprises: (a) f1 to 10 percent, based on the total weight of the cleaning concentrate, of a water soluble polymer, which comprises, as polymerized units: (i) f20 to 80 percent, based on the total weight of the polymer, of an unsaturated monocarboxylic acid monomer selected fone or more of the acrylic acid, methacrylic acid and its water soluble salts; (ii) f10 to 60 percent, based on the total weight of the polymer, of unsaturated dicarboxylic acid monomers; e (iii) f10 to 50 percent, based on the total weight of the polymer, of unsaturated non-ionizable monomers, of one or more monomers of Formula I: CH (R1) = C (R2) 0R3 (i) where : R1 is selected fhydrogen and -0-; R2 ge selects hydrogen and methyl; R3 is selected f-C (= 0) R4 and -C (= 0) OR5; R4 and R5 are independently selected f(C2-C3) alkyl; in that, when R1 is -O-, R3 is -C (= 0) R4, and R1 and R3 are joined together to form a 5-membered ring with -O- of R1 replacing R4 in -C (= 0) R4; and (b) f15 to 50 percent, based on the total weight of the cleaning concentrate, of an alkali metal hydroxide, selected fone or more of the sodium hydroxide and the potassium hydroxide and i,. 38 (c) water.

8. The cleaning concentrate according to claim 7, wherein the polymer has a weight average molecular weight of 4,000 to 10,000.

9. The cleaning concentrate according to claim 7, further comprising from 1 to 20 percent, based on the total weight of the cleaning concentrate, of conventional cleaning additives, selected from one or more forming agents, segregates, soluble surfactants. in water, anti-foaming agents, corrosion inhibitors, bleaching agents, stabilizing and staining agents, and opacifying agents.

10. A cleaning solution, formed by diluting the cleaning concentrate of claim 7, to 0.1 to 5 percent by weight of the cleaning solution, with water.

11. A method for cleaning hard surface materials, which comprises contacting a dirty hard surface material with an effective amount of the cleaning solution according to claim 10.

12. A cleaning solution, which comprises: (a) from 0.005 to 0.4 percent, based on the total weight of the cleaning solution of a water soluble polymer, which comprises, as polymerized units: (i) from 20 to 80 percent, based on the total weight of the polymer, of an unsaturated monocarboxylic acid monomer selected from one or more of the acrylic acid, methacrylic acid and its water soluble salts; (ii) from 10 to 60 percent, based on the total weight of the polymer, of unsaturated dicarboxylic acid monomers; e (iii) from 10 to 50 percent, based on the total weight of the polymer, of unsaturated non-ionizable monomers, of one or more monomers of Formula I: CH (R1) = C (R2) OR3 (i) where : R1 is selected from hydrogen and -0-; R2 is selected from hydrogen and methyl; R3 is selected from -C (= 0) R4 and -C (= 0) OR5; R4 and R5 are independently selected from (C2-C3) alkyl; in that, when R1 is -O-, R3 is -C (= 0) R4, and R! and R3 are joined together to form a 5-membered ring with -O- of R1 replacing R4 in -C (= 0) R4; and (b) from 0.1 to 3 percent, based on the total weight of the cleaning solution, of an alkali metal hydroxide, selected from one or more of the sodium hydroxide and potassium hydroxide and (c) water .

13. The cleaning solution according to claim 12, further comprising from 0.001 to 2 percent, based on the total weight of the cleaning solution, of conventional cleaning additives, selected from one or more forming agents, segregates, surfactants water-soluble, anti-foaming agents, corrosion inhibitors, bleaching agents, stabilizers, anti-age agents and opacifying agents.

14. A method for preparing the cleaning solution according to claim 12, comprising combining, as separate components, the soluble polymer n water, an aqueous solution at 20 to 50 percent of the alkali metal hydroxide, and water; in which the polymer, the alkali metal hydroxide solution and the water are added as separate streams in an in-line mixing system.

15. A method for cleaning hard surface materials, which comprises contacting the hard surface dirty material with an effective amount of the cleaning solution according to claim 12.