ZERO PHOSPHORUS HEAVY DUTY LAUNDRY DETERGENT COMPOSITION

Abstract: A solid heavy duty laundry detergent composition having a zero phosphorus content is disclosed that has the capability of effectively conditioning service water. The detergent composition comprises a source of alkalinity, a water-conditioning vinyl polymer with pendant carboxyl groups, a water-conditioning copolymer of acrylic acid and itaconic acid, and at least one nonionic surfactant.

Description: ZERO PHOSPHORUS HEAVY DDTY LAUNDRY DETERGENT COMPOSITION Field of the Invention The invention pertains to a solid heavy duty laundry detergent composition having a zero phosphorus content. More specifically, the invention pertains to a novel heavy duty detergent composition that can soften (i.e., treat divalent or trivalent hardness ions in) service water containing the detergent composition either before or during detergent action. Background of the Invention Much attention has been given in recent years to the components of detergents that treat or reduce the harmful effects of water hardness on cleaning compositions and processes. Hardness ions are typically undesirable in conjunction with washing detergents since they interfere with the soil removal mechanism of detergents. Such ions typically comprise metal ions such as calcium, magnesium, iron, manganese, and other typically divalent or trivalent metal cations depending on the source of service water used in the washing environment. In recent years, the use of effective concentrations of complex phosphates such as sodium tripolyphosphate, and other sequestrants, in detergents as water softening agents has come under increasing attack due to environmental concerns. Phosphates have been identified as contributing to excess water eutrophication, a process of algal overgrowth in environmental waters. Many state governments have found it desirable to cause detergent makers to replace phosphates with components that do not stimulate algae growth. Therefore, some states have legislated that detergent compositions have a zero phosphorus content. Currently, there are no phosphorus free heavy duty solid laundry detergent products available in the United States. Accordingly, a substantial need . exists to provide a solid heavy duty laundry detergent without intentionally added phosphates or phosphorus that has the detergency and water conditioning benefits of phosphorus-containing detergents without the associated environmental harm. Summary of the Invention We have found an improved solid heavy duty laundry detergent composition having a zero phosphorus content that effectively conditions service water. The detergent composition comprises a source of alkalinity, a water- conditioning copolymer of acrylic acid and itaconic acid, and a second vinyl polymer comprising polyacrylic acid, polymaleic acid and copolymers of acrylic acid and maleic acid and at least one nonionic detergent surfactant. We have also found a method of making a solid heavy duty laundry detergent having a zero phosphorus content in which said method avoids gel problems during manufacture of the detergent. The detergent composition of the invention provides water conditioning and detergency benefits substantially comparable to phosphorus-containing detergents without the accompanying environmental harm. The invention exhibits a level of sequestrant action substantially equivalent to condensed phosphate containing detergents. This level sequestrant action provides an effective detergent without the undesirable side effects of phosphate sequestering agents. Detailed Description of the Invention The improved solid heavy duty laundry detergent composition having a zero phosphorus content comprises a source of alkalinity, a blend of two water conditioning builder polymers and a nonionic surfactant. The builder polymer components of the detergent composition comprise a blend of two vinyl polymers having pendant carboxyl groups. The first builder polymer comprises any vinyl polymer, with pendent carboxyl groups, having hardness sequestering properties. The second builder polymer is a different polymer than the first and comprises a copolymer of acrylic acid and itaconic acid. The builder comDonents are combined with a source of alkalinity and at least one nonionic detergent surfactant, preferably a mixed nonionic surfactant system to form the detergent composition. The vinyl polymer having pendant carboxyl groups is a builder or water-conditioning agent which can act to condition wash solutions under end-use conditions and to reduce the harmful effects of water hardness. This polymer has an average molecular weight of between about 500 and about 15,000 and has in its molecular structure the groups derived from an alpha beta unsaturated mono- or dicarboxylic acid or anhydride: optionally together with the group derived from a co- monomer: H in which R 1 is hydrogen or .an alkyl group having 1 to 4 carbon atoms; R- is hydrogen, an alkyl or alkoxy group having from 1 to 4 carbon atoms, or a carboxylic acid group; R-, is hydrogen or an alkyl group having 1 to 4 carbon atoms; and R. is a hydroxyl group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an aldehyde group, or a carboxylic acid group. Specific examples of such a vinyl polymer useful in the invention include a water-soluble acrylic polymer including polyacrylic acid, polymethacrylic acid, acrylic acid-methacrylic acid copolymers, hydrolyzed polyacrylamide, hydrolyzed polymethacrylamide, hydrolyzed acrylamidemethacrylamide copolymers, hydrolyzed polyacrylonitrile, hydrolyzed polymethacrylonitrile, hydrolyzed acrylonitrile methacrylonitrile copolymers, or mixtures thereof. Water-soluble salts or partial salts of these polymers, such as the respective alkali metal (e.g., sodium, potassium) or ammonium salts can also be used. The weight average molecular weight of the polymers is from about 500 to about 15,000 and is preferably within • the range of from about 750 to about 10,000. Preferred polymers include polyacrylic acid, the partial sodium salt of polyacrylic acid or sodium polyacrylate having molecular weights of about 1,000 to about 6,000. These polymers are commercially available and methods for their preparation are well-known in the art. For example, commercially-available water-conditioning polyacrylate solutions useful in the present invention include the sodium polyacrylate solution, Colloid ® 207 (Colloids, Inc., Newark, New Jersey); the polyacrylate acid solution, Aquatreat ® Ar-602-A (Alco Chemical Corp., Chattanooga, Tennessee); the polyacrylic acid solutions (50-65% solids) and the sodium polyacrylate powders (M.W. 2,100 and 6,000) and solutions (45% solids) available as the Goodright ® K-700 series from B. F. Goodrich Co.; and the sodium or partial sodium salts of polyacrylic acid solutions (M.W. 1,000-4,500), available as the ACRYSOL^ series from Rohm and Haas. A specifically preferred polyacrylic acid useful in the invention is neutralized polyacrylic acid under the trade name Goodright K-7058N having a molecular weight of about 4500. The second polymer is different than the first. We have found that the combination of any generic carboxylate polymer with the second itaconic acid/acrylic copolymer surprisingly produces a water conditioning properly substantially equivalent to condensed phosphate sequestrants. The second polymer comprises itaconic acid and a carboxyl containing acrylic monomer. It has been found that this particular copolymer is an excellent calcium ion sequestering agent. Itaconic acid has the following chemical structure: CH 2 =C-C0 2 H CH 2 -C0 2 H and acrylic acid has the following chemical structure: 0 II CH 2 =CH-C-OCH The itaconic acid - acrylic acid copolymer employed ir. the composition of the invention can have a weight average molecular weight of about 1,500 to 100,000, preferably about 12,000 to 50,000. This copolymer can be prepared by conventional methods of polymerization well-known to those skilled in the art. The weight ratio of itaconic acid to acrylic acid is from about 0.5 to 2.0:1, preferably about 1 to 2:1. The source of alkalinity is selected from the group consisting of alkali metal hydroxides, such as sodium hydroxide, potassium hydroxide, or mixtures of each thereof. Alkali metal silicates, such as sodium metasilicate, may also be used. The preferred source of alkalinity, which is the most cost effective, is commercially available sodium hydroxide, which can be obtained in aqueous solutions at a concentration of about 50 wt-% and in a variety of solid forms of varying particle sizes. The sodium hydroxide can be employed in the invention in either liquid or solid form (powdered, beads, or pellets), or a mixture of both. Other sources of alkalinity useful include, but are not limited to, the following: alkali metal carbonates, alkali metal bicarbonates, alkali metal sesquicarbonates, alkali metal borates, and alkali metal silicate. The carbonate and borate forms are typically used in place of alkali metal hydroxide when a lower pH is desired. Silicates (Na 2 0:Si0 2 compounds) which are typically a reaction product between sodium hydroxide and silica, have a variety of Na 2 0:Si0 2 reaction molar ratios. Silicates are primarily used as alkalies and as builders in both warewashing and laundry formulations. A nonionic surfactant may be employed, either alone or in combination with other nonionic surfactants. A surfactant is a chemical compound with a hydrophobe/hydrophile balance suitable as a wetting agent, defoamer and emulsifier. Typically, surfactants are nonionic organic surface-active polymers having hydrophobic groups, blocks or chains and hydrophilic ester groups, blocks, units or chains. The hydrophobicity can be provided by an oleophilic portion of the molecule, such as an aromatic alkyl or aralkyl group, an oxypropylene unit or oxypropylene chain, or other oxyalkylene functional groups other than oxyethylene, e.g. tetramethylene oxide. The hydrophilicity can be provided with oxyethylene units, chains or blocks and/or ester groups (e.g. organo-phosphate esters), salt-type groups, or salt-forming groups. This class of synthetic detergents may be produced by the condensation of alkylene oxide groups (hydrophilic in nature) with an organic hycrophobic compound, which may be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophilic group can be readily adjusted to yield a water soluble or dispersible compound having the desired degree of balance between hydrophilic and hydrophobic elements. Nonionic synthetic surfactants suitable in the present invention include the polyethylene oxide condensates of alkyl phenols, the products derived from the condensation of ethylene oxide with the reaction product of propyiene oxide and ethylene diamine, the condensation product of aliphatic fatty alcohols with ethylene oxide as well as a ine oxides and phosphine oxides, and the products derived from the condensation of ethylene oxide with the reaction product of propylene oxide and propylene glycol. Preferred nonionic surfactants are the ethoxylated alkylphenols, such as nonylphenol ethoxylate. It has been found that a blend of a first nonylphenol ethoxylate (NPE) having a mole ratio of ethylene-oxide to nonylphenol of 9 - 10:1 and a second nonylphenol ethoxylate (NPE) having a mole ratio of ethylene-oxide to nonylphenol of 6 - 7:1 provides improved detergent action and allows for a broader range of cleaning temperature (120° F.-160 0 F.). This mixed nonionic surfactant system is particularly useful in the invention, with the first NPE and the second NPE having a weight average molecular weight of about 600 to 700 and 450 to 550, respectively. By the term "zero phosphorus" we mean no intentionally added phosphorus containing substrates such as condensed phosphates. Minute concentrations of phosphates may be present as a result of impurities or other non-intentional additions. The detergent composition of the invention can be made in any physical form, such as a cast solid, powder, granulates, pellets, or a liquid slurry. The cast solid is formed by pouring the detergent in its molten state into a cast or mold, ard allowed to solidify. The detergent composition also contains soft water and can have various additives such as fabric brighteners, fabric softeners, dyes, and fragrances. Thus, the laundry detergent composition of the present invention comprises about 10 - 50%, preferably about 35 - 45%, of a source of alkalinity; about 5 - 30%, preferably about 15 - 25%, of a water-conditioning vinyl polymer with pendant carboxyl groups, having a molecular weight of about 500-15,000, preferably about 4,000 - 6,000; about 2 - 20%, preferably about 5 - 10%, of a water-conditioning copolymer of acrylic acid and itaconic acid,- having a molecular weight of about 500 - 15,000, preferably about 10,000 - 12,000; and about 8 - 18% of at least one nonionic surfactant, preferably about 0 - 15% of a mixed nonionic surfactant system having a molecular weight of about 400 - 900, preferably about 450 - 700. A preferred source of alkalinity would be about 20 - 40% of sodium hydroxide beads and about 20 - 35% of 50 wt-% aqueous sodium hydroxide. The preferred vinyl polymer is neutralized polyacrylic acid which avoids gelling problems during manufacture of the detergent. The term "neutralized" means that the pH of the polyacrylic acid is about 5.0 - 10.0. The detergent composition further comprises about 25 - 30% of water. The present detergent composition may be readily prepared by charging an aqueous solution of an alkali metal hydroxide into a stainless steel mixing vessel having a recirculation line and pump, then agitating and heating the solution. The nonionic surfactant is then added into the vessel, followed by the copolymer of acrylic acid and itaconic acid. Fabric softener, dye, and soft water are added next. Beads of alkali metal hydroxide are next added, followed by a vinyl polymer such as polyacrylic acid. After thoroughly mixing and cooling, the composition is passed through a screen and packaged. The present invention is particularly suited for use in heavy duty institutional laundering. The term "heavy duty" refers to the ability of a detergent composition to clean various articles such as sheets, pillowcases, blankets, towels, etc. The service water employed in the laundering process dissolves the detergent composition to form an aqueous wash solution that is at a temperature of about 100 - 160° F. The wash solution is then contacted with a soiled article for a period of time effective to clean the soiled article. The invention will be further described by reference to the following detailed examples and test results which include a best mode. Example I A stainless steel mixing vessel was cha -ged with 111.2 g of 50 wt-% aqueous sodium ■ hydroxide, agitation was started and the batch was heated to 130-140° F. The nonylphenol ethoxylates (NPE 9.5, 36.0 g and NPE 6.5 19.2 g) were then added to the vessel an3 batch temperature was maintained. The copolymer of acrylic acid and itaconic acid (28.0 g) was next added slowly to maintain the temperature in the 170-190° F. range. A fabric brightener fluoresing agent (Tinopal CBS 0.3 g) was next added slowly to insure maximum dispersion. A dye (Sanogran Blue 2GLS, .0048 g) was pre-wet with a small amount of soft water (part of a 5.2952 g portion of water) before being added to the vessel. The remaining portion of soft water was then charged into the vessel. Sodium hydroxide beads (120 g) were next added slowly to the vessel and the batch temperature was maintained between 155-165° F. Neutralized polyacrylic acid (180 g) was next charged into the vessel slowly to prevent gelling. The batch was allowed to mix from 15-20 minutes and then cooled to 130-140° F. for packaging. The final weight-% of the active ingredients of Example I are summarized in Table I. Examples II-VII Table I summarizes the composition of additional solid detergents, that were prepared by the method of the invention. Table 1 Example (Final Wt-% of Ingredient) Ingredient II III IV V VI VII NaOH, 50% 22.2 26.0 26.0 44.0 44.0 29.26 26.0 NaOH, bead 17.0 Polyacrylic acid 6.0 6.0 6.0 Copolymer (acrylic and 5.6 17.96 17.96 6.0 6.0 6.0 17.96 itaconic acid) Nonionic surfactant 7.2 8.6 8.6 8.6 8.6* 8.6 8.6 (NPE 9.5) Nonionic surfactant 3.8 4.36 4.36 4.36 4.8* 4.36 4.36 (NPE 6.5) H O Fabric brightener 0.06 0.075 0.075 0.075 0.075* 0.075 0.075 (Tinopal CBS) Soft water 1.059 1.5038 1.5038 1.9638 1.5238* 1.5038 1.5038 Direct blue 86 0.0012 0.0012 0.0012 Sanogran blue 2GLS 0.0010 - 0.0012* 0.0012 0.0012 Polyacrylic acid (K-7058D) 10.0 10.0* NaOH, bead 24.0 35.5 18.5 25.0 25.0 30.0 18.5 Neutralized polyacrylic 36.0 20.0 acid (K-7058N) Fragrance 0.2 * These ingredients were premixed. While the invention has been described and fully explained in the detailed description of the specification and preferred embodiments, many embodiments of the invention can be made without departing from the spirit and scope of the invention.

Claims: WHAT IS CLAIMED IS: 1. A laundry detergent composition for use in heavy duty institutional laundering that can remove divalent or trivalent hardness ions from service water, comprising: a) about 10 - 50% of a source of alkalinity; b) about 5 - 30% of a water-conditioning vinyl polymer with pendant carboxyl groups, having a molecular weight of about 500-15,000; c) about 2 - 20% of a water conditioning copolymer of acrylic acid and itaconic acid having a molecular weight of about 500 - 15,000; and d) about 8 - 18% of at least one nonionic surfactant having a molecular weight of about 400 - 900. 2. The detergent composition of claim-1 wherein said composition is in cast solid, powder, pellets, or granulated form. 3. The detergent composition of claim 1 wherein said source of alkalinity comprising alkali metal hydroxides or alkali metal silicates. 4. The detergent composition of claim 3 wherein said alkali metal hydroxide comprises sodium hydroxide, potassium hydroxide, or mixtures thereof. 5. The detergent composition of claim 3 wherein said alkali metal silicate comprises sodium metasilicate. 6. The detergent composition of claim 4 wherein said sodium hydroxide comprises about 20 - 40% of sodium hydroxide beads and 20 - 35% of 0.50 wt-% aqueous sodium hydroxide. 7. The detergent composition of claim 1 wherein said vinyl polymer comprises an acrylic polymer. 8. The detergent composition of claim 7 wherein said acrylic polymer comprises polyacrylic acid, the partial sodium salt of polyacrylic acid, sodium polyacrylate, or mixtures thereof, having a molecular weight of about 750- 10,000. 9. The detergent composition of claim 8 wherein said polyacrylic acid is neutralized. 10. The detergent composition of claim 1 wherein said nonionic surfactant comprises a blend of a first nonylphenol ethoxylate having a molecular weight of about 450 - 500 and a second nonylphenol ethoxylate having a molecular weight of about 600 - 700. 11. The detergent composition of claim 1 wherein said composition has a zero phosphorus content. 12. The detergent composition of claim 1 wherein the vinyl polymer is a salt or partial salt of the vinyl polymer. 13. A laundry detergent composition having a zero phosphorus content that can remove divalent or trivalent hardness ions from service water suitable for use in heavy duty laundering comprising: a) about 10 - 50% of an alkali metal hydroxide comprising sodium hydroxide, potassium hydroxide, or mixtures thereof; b) about 5 - 30% of an acrylic polymer comprising polyacrylic acid, the partial sodium salt of polyacrylic acid or sodium polyacrylate having a molecular weight of about 1,000-6,000. c) about 2 - 20% of a water conditioning copolymer comprising acrylic acid and itaconic acid, having a molecular weight of about 500 - 15,000; d) about 8 - 18% of a mixed nonionic surfactant system comprising a first and second nonylphenol ethoxylate having weight average molecular weights of about 450 - 500 and 600 - 700 respectively. 14. A process for cleaning a soiled article using a heavy duty laundry detergent composition that can condition service water by removing divalent or trivalent hardness ions comprising: a) dissolving in water an effective amount of said detergent composition, thereby forming an aqueous wash solution, said detergent composition comprising: i) about 10 - 50% of a source of alkalinity; ii) about 5 - 30% of a water-conditioning vinyl polymer with pendant carboxyl groups, having a molecular weight of about 500 - 15,000; iii) about 2 - 20% of a water-conditioning copolymer of acrylic acid and itaconic acid, having a molecular weight of about 500 - 1,500; and iv) about 8 - 18% of at least one nonionic surfactant having a molecular weight of about 450 - 700; and b) contacting said aqueous wash solution of (a) with said soiled article for a period of time effective to clean said soiled article. 15. The process of claim 14 wherein said detergent composition is in cast solid, powc ' er, granulated, or pellet form. 16. The process of claim 14 wherein said source of alkalinity comprises alkali metal hydroxides or alkali metal silicates. 17. The process of claim 16 wherein said alkali metal hydroxides comprise sodium hydroxide, potassium hydroxide, or mixtures thereof. 18. The process of claim 16 wherein said alkali metal silicates comprise sodium metasilicate. 19. The process of claim 17 wherein said sodium hydroxide comprises about 20 - 40% of sodium hydroxide beads and 20 - 35% of 0.50 wt-% aqueous sodium hydroxide. 20. The process of claim 14 wherein said vinyl polymer comprises an acrylic polymer. 21. The process of claim 20 wherein said acrylic polymer comprises polyacrylic acid, the partial sodium salt of polyacrylic acid, sodium polyacrylate, or mixtures thereof, having a molecular weight of about 750-10,000. 22. The process of claim 21 wherein said polyacrylic acid is neutralized. 23. The process of claim 14 wherein said nonionic surfactant comprises a blend of a first nonylphenol ethoxylate having a molecular weight of about 450 - 500 and a second nonylphenol ethoxylate having a molecular weight of about 600 - 700. 24. The process of claim 14 wherein said detergent composition has a zero phosphorus content. 25. The process of claim 14 wherein said aqueous wash solution is applied to said soiled article at about 100 - 140° F. 26. The process of claim 14 wherein the vinyl polymer is a salt or partial salt of the vinyl polymer. 27. A method of preparing a heavy duty solid laundry detergent composition that can condition service water comprising: a) charging about 10 - 50% of an alkali metal hydroxide into a mixing vessel; b) adding about 5 - 30% of a water conditioning acrylic polymer having a molecular weight of about 750-10,000. c) adding about 2 - 20% of a water-conditioning copolymer of acrylic acid and itaconic acid having a molecular weight of about 500 - 15000; and d) adding about 8 - 18% of at least one nonionic surfactant having a molecular weight of about 450 - 700. 28. The method of cla ; m 27 wherein said alkali metal hydroxide comprises sodium hydroxide, potassium hydroxide, or mixtures thereof. 29. The method of claim 28 wherein said sodium hydroxide comprises about 20 - 40% of sodium hydroxide beads and 20 - 35% of 0.50 wt-% aqueous sodium hydroxide. 30. The method of claim 27 wherein said acrylic polymer comprises polyacrylic acid, the partial sodium salt of polyacrylic acid, sodium polyacrylate, or mixtures thereof. 31. The method of claim 30 wherein said polyacrylic acid is neutralized. 32. The method of claim 27 wherein said detergent composition has a zero phosphorus content. 33. The method of claim 27 wherein said nonionic surfactant comprises a blend of a first nonylphenol ethoxylate having a molecular weight of about 450 - 500 and a second nonylphenol ethoxylate " having a molecular weight of about 600 - 700. 34. The method of claim 27 wherein said detergent composition is in cast solid, powder, granulated, or pellet form.

Inventors: HEILE BERNARD J, TALLMAN DANIEL N, TARARA JAMES J, HEILE, BERNARD, J., TALLMAN, DANIEL, N., TARARA, JAMES, J.
Applicants: ECOLAB INC, ECOLAB INC.
Application year: 1989
Main classification: C11D3
IPC codes: C11D1, C11D3