MXPA01013328A - Surfactant emulsions and structured surfactant systems. - Google Patents

Abstract

A mixture of an ethoxylated non-ionic surfactant having an average of 20 to 100 ethylene-oxy groups per molecule with from 10 to 150 parts by weight of a water soluble thiocyanate stabilises non-ionic emulsions and in particular deflocculated non-ionic structured surfactant systems by raising the lamellar/L2 phase transition temperature.

Description

SURFACTANT EMULSIONS AND STRUCTURED SURFACTANT SYSTEMS The present invention relates to emulsions of nonionic surfactants and to the formulation of structured suspension systems of surfactants. The formulation of laundry detergents is particularly relevant, especially those used for industrial and institutional cleaning.

Structured Surfactant Solids solids in liquids present a problem. If the solids differ in density of liquid they will tend either to sediment or to float. Increasing the viscosity of the liquid may retard, but not prevent, this separation, and high viscosities are generally undesirable. Colloidal systems, which the suspended particles are small enough to experience Brownian motion, for example, less than one mine, may be kinetically stable. However, the difficulty or non-desirability of grinding some solids to these sizes, and the impossibility of maintaining many of them at this level in front of the growth or agglomeration of the crystal, limits the use of colloidal suspensions.

The adjustment of the density of one phase to correspond to that of the other is usually impracticable. In addition, these systems are almost always unstable at temperature due to the differential proportions of thermal expansion. A suspension method that allows even relatively large particles to be stably suspended is a structured surfactant. The term covers systems in which a mesophase of surfactant, usually a lamellar phase or G phase, alone or more usually interspersed with an aqueous phase, provides a rning deformation load that is sufficient, when the system is at rest, to immobilize any particle suspended, but that is sufficiently low, to allow the system to pour out like a normal liquid. These systems can exhibit very low apparent viscosities when agitated, pumped or poured and are still capable of holding particles, sometimes a size of millimeters or larger, indefinitely in suspension. Three main types of suspension systems have been used in practice, all comprising a G phase, in which the bilayers of the surfactant are arranged with the hydrophobic part of the molecule in the interior and the hydrophilic part on the outside of the bilayer (or vice versa). The blcapas are side by side, for example, in a parallel or concentric configuration. V ^ Sometimes separated by aqueous layers. The G phases (also known as phases? ¾) can usually be identified by their characteristic textures under the polarization microscope and / or by X-ray diffraction, which is often able to detect evidence of laminar symmetry. This evidence can comprise peaks of first, second, and sometimes third order with d - '? ^ 10 spaced (27t / Q, where Q is the moment transfer vector) in a simple integral ratio of 1: 2: 3. Other types of symmetry give different relationships, usually not integrals. Most surfactants form a G phase either at room temperature or some higher temperature when mixed with water in certain specific proportions. However, these G phases can not usually be used as structured suspension systems. Useful amounts of solid make them invertible and small amounts tend to settle. The main types of the structured system used in practice are based on the dispersed laminar, spherulitic and expanded laminar phases. The dispersed lamellar phases are two phase systems in which the bilayers of surfactants are arranged as parallel plates to form domains of G phases which are intermixed with an aqueous phase to form a gel-like opaque system. They are described in EP 0 086 614. The spherulitic phases comprise well-defined spheroidal bodies 5, usually referred to in the art as spherulites, in which the bilayers of surfactants are arranged as concentric covers. The spherulites usually have a diameter in the range of 0.5 to 10 microns and are dispersed in an aqueous phase in the manner of a classical emulsion, but which interact to form a structured system. Spherulitic systems are described in more detail in EP-0 151,884. The more structured surfactant systems are intermediate between the dispersed laminar and the spherulitic, comprising both types of structure. Usually, systems that have a more spherulitic character are preferred because they tend to have lower viscosity. A variant of the spherulitic system 20 comprises bodies in the form of a rod or prolate, sometimes referred to as rods. A third type of structured surfactant system comprises an expanded G phase. It differs from the other two types of structured systems in being essentially an individual phase, and in the conventional G phase and having a narrower d-spacing. The conventional G phases have a d-spacing of approximately 5 to 7 nanometers. Attempts to suspend solids in these phases result in rigid pastes that either can not be poured, are unstable or both. The phases 6 expanded with d-spacing between 8 and 20, for example between 10 to 15 nanometers, are formed when the electrolyte is added to the aqueous surfactants at concentrations just below those required to form a normal G phase, particularly agents surfactants in the M phase. The M phase comprises surfactant molecules arranged to form cylindrical rods of indefinite length. They display hexagonal symmetry and a distinctive texture under the polarization microscope. Typical M phases thus have a high viscosity so that they appear to be solid set. The M phases near the lower concentration limit (the Lj / M phase limit) can be poured but have a very high viscosity and often a mucus-like appearance. These systems tend to form G phases expanded in a particularly easy manner in the addition of sufficient electrolyte. The expanded G phases are described in more detail in EP-0 530,708. In the absence of suspended matter, they are translucent, different from the scattered lamellar or spherulitic phases that are necessarily opaque. They are optically anisotropic and have a viscosity dependent on the shear stress. In this, they differ from the phases which are micellar solutions 5 and which include microemulsions. The L1 phases are clear, optically isotropic and substantially Newtonian. They are not structured and can not suspend solids. Some Lx phases exhibit small angle X-ray diffraction spectra that show evidence of hexagonal symmetry. These phases usually have concentrations about the phase limit of Lj / M and can form G phases expanded by the addition of electrolyte. The more structured surfactant systems require the presence of electrolyte as well as surfactant and water in order to form structured systems capable of suspending solids. However, certain relatively hydrophobic surfactants such as ^ - 'as isopropylamine-alkylbenzene sulfonate can form spherulites in water in the absence of electrolyte. These surfactants are capable of suspending solids in the absence of electrolyte as described in EP-0 414,549.

Flocculation A problem with surfactant systems, structured, two-phase, and especially spherulitic systems, is the flocculation of dispersed structures of surfactant. This tends to occur at a high concentration of surfactant and / or high electrolyte. It can have the effect of rendering the composition very viscous and / or unstable with the dispersed surfactant that is separated from the aqueous phase. It has been found that certain amphiphilic polymers act as deflocculants of structured surfactants. One type of deflocculating polymer exhibits cteniform architectures (comb shape) with a hydrophilic structure and hydrophobic side chains or vice versa. A typical example is a random copolymer of chemical acid and a fatty alkyl acrylate. Cteniform deflocculants have been described in a large number of Patents, for example, WO-A-9106622. A more effective type of deflocculant has surfactant instead of a cteniform architecture, with a group of hydrophilic polymer attached at one end to a hydrophobic group. These deflocculants are typically telomeres formed by telomerizing a hydrophilic monomer with a hydrophobic telogen. Examples of surfactant deflocculants include alkyl thiol polyacrylates and alkyl polyglycosides.

Defoamers of surfactants are described in more detail in EP-0 623,670. A disadvantage of both surfactant deflocculants and Cteniformes is that the concentration required to deflocculate at the optimum viscosity is critical within near narrow limits and varies with temperature. Either too opaque or too much deflocculant causes instability and / or excessive viscosity. As a result, deflocculated systems tend to separate if the temperature varies significantly. In particular, there is a tendency to form a clear bottom layer at prolonged rest. One approach to the problem of temperature stability has been to add highly crosslinked polyacrylates (see US 5, 602,092). These are difficult to disperse in the liquid of the structure. The co-pending application of the same date describes the use of certain copolymers to prevent bottom separation.

Applications of Structured Surfactant Structured surfactants have been applied to the problems of suspending: additives insoluble in water or hardly soluble in laundry detergent; antifoams and enzymes in laundry detergents and other systems of surfactants, abrasives and hard surface cleaners; pesticides and oils in agrochemical preparations (EP-0,388 239 and EP 0 498,231); rock cuttings in drilling muds (EP-0,430, 602); dyes in concentrates of dyebaths and printing inks (EP-0,472,089); powders, oils and other cosmetic ingredients in personal care formulations.

The Problem An additional class of temperature stability is frequently observed with more concentrated structured surfactants, especially structured, deflocculated surfactants. Typically, it comprises the sedimentation of the suspended solid when the composition is stored under hot conditions. It is now believed that this separation may be due to a tendency for a phase change in the surfactant of the dispersed or spherulitic laminar phase to the L2 phase at elevated temperature. A similar problem sometimes arises when attempts are made to prepare emulsions of nonionic surfactant at high concentrations. A particular problem arises in relation to liquid detergents suitable for use in industrial and institutional laundries, such as factories, hospitals and hotels and especially in automatically dosed washing machines. A laundry detergent ideal for institutional use would combine: high levels of surfactant and in particular high levels of non-ionic surfactant, which has been found particularly effective in removing dirt; high alkalinity, to saponify the greasy dirt; and high levels of additive, which improve the performance of the surfactant by counteracting the effects of calcium in water. The composition should be homogeneous and pourable and the concentration as high as possible. Unfortunately, in general it is difficult to combine the surfactants with electrolytes at high concentrations to form stable compositions. It has proven particularly difficult to achieve this with nonionic surfactants that are not capable of forming stable solutions at high alkalinity or in the presence of electrolyte, except at very low concentrations that are too low to be commercially acceptable. As a result, so far it has been usual to use two separate solutions in institutional machines, one to supply the surfactant and a separate solution as the source of the alkali. Attempts to combine the two in an individual formulation have not been successful to date. Even the use of a deflocculant such as that described in EP-A-0 623 670 or EP-A-0 346 995 has not been successful in the formation of a sufficiently stable homogenous phase of commercially acceptable concentration, or has to be done on a very restricted temperature range.

The Solution It has now been discovered that a mixture of a non-ionic, highly ethoxylated surfactant and an alkali metal thiocyanate can form highly concentrated emulsions which are stable at temperature and also improves the temperature stability of structured, deflocculated surfactants. . It is easily dispersed in aqueous systems, which become less sensitive to variations in temperature, in this way. The mixture is particularly useful to allow instability in the concentrated industrial and institutional detergent. It is believed that the mixture inhibits the transition from a G phase or structured system to an L2 phase by raising the phase transition temperature.

The Invention The present invention, according to a first embodiment, provides a mixture of an ethoxylated nonionic surfactant having an average of 20 to 100 ethylene-oxy groups per molecule with 0.1 to 150 parts by weight and a water-soluble thiocyanate. . According to a second embodiment, the invention provides a concentrated, non-ionic surfactant emulsion comprising water and the mixture in a concentration adapted to form an emulsion or G phase at a temperature below 40 ° C. According to a third embodiment, the present invention provides a structured composition of surfactant capable of suspending solids comprising a structuring surfactant, water, and if an electrolyte in relative proportions adapted to form a structured system of surfactant is required, dispersed and / or spherulitic laminate, capable of forming an L2 phase at some temperature below 50 ° C and optionally sufficient of a desfluculant to inhibit flocculation of the system, characterized in that the composition comprises an effective amount of a phase stabilizer which is a mixture of (i) an ethoxylated nonionic surfactant having from 20 to 100 ethylene-oxy groups and (ii) a water-soluble thiocyanate in a relative molar ratio (i): (ii) from 1: 200 to 20 :1. Preferably, the structuring surfactant consists of a major amount of nonionic surfactant, typically an ethoxylate with 1 to 15, for example, 2 to 10 ethylene oxide units and optionally a minor amount of anionic surfactant and / or amphoteric. Preferably, the water is present in a proportion of 20 to 60%. Preferably, the electrolyte comprises an alkali.

The Phase Stabilizer The stabilizer may comprise a straight or branched chain fatty acid or alcohol of 8 to 20 carbon atoms, ethoxylated, fatty amine, sorbitan or sorbitan ester or glycerol, alkyl-polypropoxy group or alkyl-phenyl group. The number of ethoxy groups can be from 20 to 100, for example from 30 to 80, preferably from 40 to 60. The molar ratio of (i): (ii) can be preferably from 1: 100 to 10: 1, for example 1:50 to 5: 1. When adding a structured surfactant system, it is preferred that the surfactant (i) be present in an amount of 0.1 to 3% by weight of the total composition, preferably 0.2 to 2%. The maximum concentration depends on the amount of structuring surfactant present, higher levels are preferred for higher concentrations of structuring surfactant. Excessive amounts break the structures. The thiocyanate is preferably present in an amount greater than 0.5%, more preferably greater than 0.1%, for example, greater than 0.5%. The upper limit is not critical, but concentrations greater than about 10% are unlikely to provide additional benefit. Concentrations greater than 2% are generally ineconomic. The thiocyanate may be any water-soluble thiocyanate, but is preferably an ammonium or alkali metal thiocyanate and more preferably a potassium thiocyanate.

Institutional and Industrial Formulations According to a preferred embodiment, the invention provides a detergent composition comprising: (A) from 10 to 50% by weight of the water composition, (B) at least 3% based on the weight of the composition , preferably from 4 to 10%, of a structured surfactant comprising more than 50% based on the total weight of the surfactant of nonionic surfactants having an average HLB of 8 to 15 and optionally a smaller proportion of anionic and / or amphoteric surfactant; (C) at least 10% by weight based on the weight of the composition of the additives; v (D) at least 7% based on the weight of the composition of salts that do not form dissolved micelles, and 5 bases that dissociate at least partially in solution in ions, including any dissolved portion of the additive; (E) a total free alkalinity of at least 0.5 normal; (F) sufficient of a deflocculant to provide, in conjunction with components A to E, above a pourable composition that does not separate after 1 month at 25 ° C; wherein there is additionally from 0.01% to 5% by weight of an auxiliary stabilizer consisting of 15 alcohol ethoxylates of 8 to 20 carbon atoms having an average of 25 to 100 ethylene-oxy groups per molecule, together with a soluble thiocyanate in water, preferably potassium. The amount of water is typically greater than 15-20%, preferably greater than 15%, preferably greater than 20%, especially greater than 25% and usually greater than 30% based on the total weight of the composition. The structuring surfactant is preferably completely non-ionic since in some applications the inclusion of the anionic surfactant can adversely affect performance. However, where the anionic surfactant can be tolerated for inclusion, it has the advantage of allowing higher total concentrations of the surfactant to be more easily achieved. Typically, the formulations based entirely on nonionic contain from 7 to 30%, more typically from 10 to 25% by weight of surfactant while compositions containing a minor proportion of anionic surfactant can contain up to 50% by weight. weight, for example from 15 to 40%, especially from 20 to 35%. The nonionic surfactant consists preferably of 60 to 100% by weight of alkoxylate, preferably ethoxylate or ethoxylate / mixed propoxylate. Typically, it comprises natural or synthetic alcohols of 10 to 18 carbon atoms, especially 8 to 20 carbon atoms, ethoxylated. The alcohols are typically primary or secondary, straight or branched chain, saturated or unsaturated. Also effective are alkoxylated fatty acids, fatty amines, alkylphenols, mono- and dialkyl glyceryl esters and sorbitan esters. The ethoxylate typically comprises an average of 1 to 10 alkoxy groups depending on the length of the alkyl chain, to give an HLB of 10 to 15, preferably 12 to 14. The nonionic surfactant may comprise a mono- or di-ethanolamide or an amine oxide. The surfactant may optionally contain a minor proportion (ie, less than 50%, based on the total weight of the surfactant) of the anionic surfactant such as soap and / or alkylbenzene sulfonate. Other anionic surfactants that can be used include alkyl ether sulfates, and alkyl sulphates, or olefin sulfonates, paraffin sulphonates, and alkyl phosphates. The additive is preferably sodium tripolyphosphate, but may alternatively be or comprise sodium or potassium pyrophosphate, sodium or potassium citrate, sodium or potassium carbonate or a zeolite. Other additives include EDTA, nitrilotriacetate, phosphonates and poly-electrolytes such as polyacrylates or polymaleate. The term "additive", as used herein, excludes any hydroxyl used to provide the free alkali but includes carbonate and silicate. The additive is present in amounts greater than 10% by weight based on the total weight of the composition, preferably more than 15%. The additive levels can be above 20%, any excess over the solubility in the system that is present as suspended particles. The concentrations of the additive do not normally exceed 50% by weight and are usually less than 40%, for example less than 30%. The composition contains a total of at least 7% by weight of solubilization salts of dissolved surfactant, and bases. This includes any dissolved portion of the additive and any alkali required to provide the free alkalinity. Excludes micelle formation components such as anionic surfactant. The dissolved salts and bases preferably constitute 10 to 40%, for example 15 to 30% by weight of the composition, and sufficient to form a multi-phase system in which an aqueous phase is mixed with a mesophase of surfactant agent. The total free alkali must be sufficient to neutralize at least an equal volume of 0.5 normal HCL. Preferably, the free alkalinity is from 0.7 to 2 normal, for example 0.8 to 1.5. It is particularly preferred that the compositions of the invention contain a deflocculant. The deflocculant may be a polycarboxylate having one or more alkyl groups such as CB-20-alkyl-thiol polycarboxylate, for example, polyacrylate or polymaleate or a copolymer of unsaturated carboxylic acid with a C 8-20-alkyl ester of an acid unsaturated carboxylic acid, for example, a copolymer of acrylic acid and / or maleic acid with a minor proportion of a C8-20 alkyl acrylate and / or alkylmalemaleate ester. Alternatively, it may comprise an alkyl polyglycoside. The alkyl polyglycoside is preferably a polyglucoside and typically has an average degree of polymerization between 1.3 and 10, more usually 1.5 to 3. The deflocculant is generally added in an amount sufficient to provide a spreading of the aqueous phase with the surfactant phase at 25 ° C, which is not separated in the space of 1 hour. This may typically require from 0.5 to 10, more usually from 1 to 5%, for example from 2 to 4.5% by weight based on the weight of the composition. The amount is preferably adjusted to obtain a spherulitic composition comprising surfactant vesicles, usually having a multilamellar or G-phase structure, dispersed in an aqueous phase. The auxiliary stabilizer may be present in proportions of up to 5% by weight, usually from 0.01 to 3%, for example from 0.02 to 2, especially from 0.01 to 1. Combinations of two are more auxiliary stabilizers can sometimes be particularly effective. The detergent compositions of the invention also preferably contain minor, conventional detergent ingredients including antifoams such as silicone foams, soil suspending agents such as carboxymethylcellulose, optical brighteners, stain removers such as enzymes, bleach include perborate mixtures. -metaborate, sequestrants such as phosphonates and especially amino-phosphonates including aminotrismethylene phosphonate, ethylene-diamine-tetrakis (methylene phosphonate), and ethylene-thiamine-pentakis (methylene phosphonate) and others in the same series, perfumes, dyes , preservatives, corrosion inhibitors, bleach activators such as TAED and / or conditioners. The above minor ingredients may all be present in conventional amounts and usually constitute a total of less than 5% by weight of the composition, typically less than 1%. The anionic component of the ionic ingredients may typically be sodium, potassium or a mixture of the two. Potassium is preferred where very high solids contents are desired. The invention is illustrated by the following examples in which all the proportions are by weight of the material at 100% based on the weight of the composition.

The previous product was an industrial and institutional laundry detergent, effective. In the absence of the alkyl polyglycoside, the composition was heavily flocculated and experienced rapid separation. In the absence of potassium thiocyanate and / or fifty percent mole ethoxylate, the product was separated at temperatures above 30 ° C.

Claims (7)

1. CLAIMS 1. A mixture of an ethoxylated nonionic surfactant having an average of 20 to 100 ethylene-oxy groups per molecule where 0.1 to 150 parts by weight of a water-soluble thiocyanate.
2. 2. A concentrated, non-ionic surfactant emulsion comprising water, and the mixture in a concentration adapted to form an emulsion or G phase at a temperature below 40 ° C.
3. 3. A structured composition of surfactant capable of suspending solids comprising a structuring surfactant, water, and if required, electrolyte in relative proportions adapted to form a dispersed and / or structured spherulitic layered surfactant system capable of forming a phase L2 at some temperature below 50 ° C and optionally enough from a deflocculant to inhibit flocculation of the system, characterized in that the composition comprises an effective amount of a phase stabilizer which is a mixture of (i) a surfactant non-ionic ethoxylate having from 20 to 100 ethylene-oxy groups and (ii) a water-soluble thiocyanate in a relative normal ratio (i): (ii) from 1: 200 to 20: 1
4. 4. A composition according to claim 3, wherein the structural surfactant comprising a major amount of a nonionic surfactant and a minor amount of anionic surfactant and / or Amphoteric
5. 5. A composition according to any of claims 1 and 2, wherein the stabilizer comprises a fatty alcohol of 8 to 20 carbon atoms ethoxylated.
6. 6. A detergent composition comprising: (A) from 10 to 50% by weight of the water composition, (B) at least 3% based on the weight of the composition, of a structured surfactant comprising more than 50 % based on the total weight of the surfactant of nonionic surfactants having an average HLB of 8 to 15 and optionally a smaller proportion of anionic and / or amphoteric surfactant, - (C) at least 10% by weight based on to the weight of the composition of additives; (D) at least 7% based on the weight of the composition of salts of non-formation of dissolved micelles, and bases which are at least partially dissociated in solution in ions, including any dissolved portion of the additive; (E) a total free alkalinity of at least 0.5 normal; (F) sufficient of a deflocculant to provide, in conjunction with the above components A to E, a pourable composition which does not separate after 1 month at 25eC; wherein there is additionally from 0.01% to 5% by weight of an auxiliary phase stabilizer consisting of alcohol ethoxylates of 8 to 20 carbon atoms having an average of 25 to 100 ethylene-ox groups per molecule, together with a thiocyanate soluble in water.
7. 7. A composition according to claim 6, wherein the thiocyanate is potassium thiocyanate.