JP2003511391A - Structured surfactant system - Google Patents

Abstract

  (57) [Summary] The primary layer phase (disc-like micellar optical isotropic phase exhibiting transient anisotropy under stress) can suspend solid particles. In particular, it is effective for suspending pearlescent agents.

Description

Detailed Description of the Invention

The present invention relates to a new type of structured surfactant system. This novel system is especially incorporated into liquid formulations such as shampoos and toiletries to suspend pearlising concentrates to capture consumer-attractive pearlescence. It is suitable and can prevent inhomogeneities in the formulation.

Structured surfactant systems can be poured (
Pourable) with the ability to suspend solid particles indefinitely. While the system is stationary, it behaves like a solid gel holding immobile particles, but the shearing force associated with pouring destroys its structure, causing the suspension to flow like a mobile liquid. .
Known structured surfactant systems are opaque diffuse or cloudy opalescent layered phases of a surfactant mesophase with an aqueous phase.

Pearlescent agents typically include small, thin, transparent, plate-like crystals,
It can be suspended in a parallel arrangement. When so suspended, the light cast on the crystal undergoes a number of complex reflections within the matrix similar to those produced by pearls, causing similar optical interference effects.

Natural pearls consist of alternating layers of calcium carbonate and protein. As artificial pearlescent agents, guanine / hypoxanthine crystals extracted from fish scales, mica,
Various salts of lead, zinc, mercury and bismuth (eg bismuth oxychloride), titanium oxide, and magnesium stearate, coconut monoethanolamide,
Included are various fatty acid derivatives such as ethylene glycol distearate and ethylene glycol monostearate. Fish scale extracts are too expensive and inorganic pearlescent brighteners are either too toxic (eg lead, mercury) or relatively ineffective (eg bismuth) for general use in toiletries. Therefore,
Fatty acid derivatives are currently the most widely used pearlescent brighteners. In addition to the chemical and physical form of the pearlescent brightener, the manner in which it is suspended has a significant effect on its visual impact. When incorporating pearlescent brighteners in aqueous formulations, sometimes difficulties are encountered in obtaining the desired effect.

Conventional fatty acid-derived pearlescent brighteners are supplied as solids, which are usually added to formulations heated above their melting point and recrystallized in situ. To obtain acceptable results, the crystallization conditions, especially the amount and nature of the agitation applied, must be carefully controlled. This makes it difficult to obtain a consistent effect and makes it inconvenient to use solid pearlescent brighteners.

Attempts have been made to prepare liquid concentrates or suspensions that can be added directly to shampoo formulations without heating. While more convenient for the user, such concentrates expose manufacturers to the problem of obtaining a highly consistent pearl effect similar to that of users of traditional solid pearlescent brighteners. There are also difficulties in keeping the particles in a stable suspension to prevent settling.

The present inventors have now discovered that the concentration that typically produces a liquid crystal layer (eg typically 18-30
%, Certain surfactants with high solubility parameters, such as alkyl ether sulphates, are mobile, transparent protolamellar in the presence of sufficiently high concentrations of electrolytes. It was found to form the L ₁ phase. These mobile phases are transparent, optically isotropic, and typically less viscous than the standard G phase, but have the ability to form stable suspensions of solids such as pearlescent brighteners. Have.

The original lamellar phase is transparent and optically isotropic, but is distinctly unique in that it exhibits the suspending properties of a structured surfactant system. The inventors believe that the proto-lamellar phase comprises oblate (disc) micelles that can accept parallel layered orientations. They are typically placed when placed between orthogonal polarizers and stressed, for example by tapping or shaking, when a flash is observed when the system temporarily forms an anisotropic structure. To be done.

When the pearlescent brightener is suspended in the original lamellar phase, it promotes a parallel oriented structure of pearlescent crystals that maximizes the pearlescent effect even in the absence of agitation. The concentrate is
It is easily pourable, but generally does not tend to separate on standing and can be easily added to shampoo formulations without heating to give a highly consistent pearlescent effect.

The preferred surfactant, alkyl ether sulfate, is the present composition because it is the most commonly used ingredient in shampoo formulations because of its mildness to the skin and relatively good lathering properties. Is particularly useful. Thus, the concentrate can be placed in a shampoo formulation without introducing anything unrelated to the formulator's needs. The optical clarity of the original lamellar phase allows the pearlescent effect to be clearly observed without clouding due to the surfactant structure as occurs when using any of the previously known structured surfactants.

When alkyl ether sulphates or similar water-soluble surfactants dissolve in water at relatively low concentrations, they cause the surfactant molecules to be arranged in spherical clusters (micelles) to form a clear micellar solution (L1). Form). With increasing concentration, micelles form rods of increasing length (oblong micelles), which increases the viscosity. When the concentration is further increased, the rod-shaped bodies come to be aligned, which causes an abnormal decrease in viscosity.
Aligned rod micellar or protohexagonal systems are optically transparent, pourable, and may show hexagonal symmetry when examined by small angle X-ray diffraction (SAX), and the momentum transfer vector Q ₁ 1st order peaks, and, if the system is well-defined, one or more gradual increments with Q values at the following ratios: Q ₂ = Q ₁ √3; Q ₃ = 2Q _1. Gives a smaller higher ranking peak. These ratios are characteristic of hexagonal symmetry.

[0012]   When the concentration was further increased, the rod length increased indefinitely, and the immobile M phase formed.
Is made. This is typically observed at surfactant concentrations of about 30% by weight. M phase
Also shows the SAX peak in the characteristic ratio of hexagonal symmetry. It typically
For very viscous mucus properties such as curd or gelatinous solids or fluids
Similar Increasing the concentration of alkyl ether sulfate to about 55-60% by weight,
A standard lamellar phase or G phase is typically formed. It is a shear dependent viscosity
And a movable birefringent liquid crystal having layered symmetry and a characteristic ratio: Q₂= 2Q₁, Q ₃ = 3Q₁This is revealed by the SAX peak with. These peaks range from about 3
3 shows a structure with a repeat spacing of 5 nm (d = 2π / Q1). Standard G phase yields
And relatively mobile as compared to the M phase, but with the presence of a significant amount of suspended solids.
As a suspension medium for solids so that it cannot pour it
It is generally not suitable for use. Higher surfactant concentrations are a further disadvantage
is there.

However, when sufficient electrolyte is added to the micellar or original hexagonal solution of alkyl ether sulphate, the transformation from oblong micelles to oblate spheres and hexagonal symmetry typically results in d in the range of 6-15 nm. There is a corresponding shift to the layered symmetry with spacing. Such a phase can suspend the solid and remain ready for pouring.

The present invention provides the use of an original layered aqueous surfactant for suspending solid particles, especially pearlescent brighteners.

The present invention further provides a suspension of solid particles in an aqueous surfactant, wherein said surfactant is in the original lamellar phase. In a preferred embodiment, the suspended particles are
Contains pearlescent particles.

The surfactant is preferably a C _10-18 alkyl or alkenyl 1-10 mole ethoxy sulphate, more commonly a C _12-14 alkyl ethoxy sulphate, preferably an alkyl 1-5 mole ethoxy. It is a sulfate. Alternatively, the ether sulphate may be mixed propoxy ethoxy sulphate or alkyl glyceryl or alkyl glyceryl polyethoxy sulphate. The cation of the alkyl ether sulphate salt is preferably sodium but may also be a C _1-6 amine such as potassium, lithium, ammonium or alkanolamines.

Surfactants are small amounts of other surfactants, especially anionic, nonionic or amphoteric surfactants such as alkyl sulphates, alkyl benzene sulphonates, paraffin sulphonates, olefin sulphonates. , Alkyl sulfosuccinates, soaps, taurides, isethionates, alkyl ethoxylates, fatty acid ethoxylates, alkyl glyceryl ethoxylates, alkyl carbohydrate ethoxylates, amine oxides or betaines. However, it is generally preferred to use essentially only alkyl ether sulfates.

The electrolyte is preferably sodium chloride, but may for example be sodium carbonate, sodium citrate, sodium tripolyphosphate, sodium hydroxide or any other salt which tends to salt out the alkyl ether sulphate from solution or It can be a base. Electrolyte cations include sodium, potassium, lithium, ammonium,
Or, less preferably, it may be an amine such as an alkanolamine or a mixture of any of the above.

The choice of electrolyte and co-surfactant, if present, is adjusted according to which ingredients the formulator, to which the concentrate is supplied, wants to or can tolerate in the final formulation. Good.

In general, the surfactant is used in the absence of an electrolyte in a total concentration which will correspond to the clear L ₁ phase or the original hexagonal phase. Typically, electrolyte-free surfactant / water systems will be unstructured or exhibit hexagonal symmetry under SAX. The required concentration will vary with different surfactants, but will generally be 17-30% by weight of the total weight of the composition, more typically 19-28%.

[0021] The amount of electrolyte is such that the ethersulfate / water mixture is mixed from an optically isotropic and transparent L ₁ phase or a raw hexagonal phase exhibiting hexagonal symmetry to a transparent source which typically exhibits layered symmetry under SAX. An amount sufficient to convert to a lamellar phase. The amount required will depend on the nature and concentration of the surfactant. Typically it will be from 1 to 10% by weight of the total composition, more usually from 2 to 5% by weight. Sodium citrate is more expensive than sodium chloride and most effective at concentrations of 4-10%, but it can be loaded higher with pearlescent brighteners.

The pearlescent brightener may be any previously described herein, including natural and inorganic pearlescent brighteners, but is preferably a fatty acid derivative, especially ethylene glycol disteare. It is a mixture of rate and ethylene glycol monostearate.

The pearlescent brighteners may be dispersed in the aqueous structural surfactant system, for example by gentle stirring, but in the case of fatty acid derivatives preferably their melting point (eg 65-80 ° C.). Above) and preferably with sufficient agitation to disperse the liquid pearlescent brightener in the structured surfactant system to form droplets of 1-60 microns (eg 15-50 microns). And prepared on the spot by cooling to ambient temperature. Preferably, the cooling is relatively slow (eg allowing the mixture to cool naturally). The amount of pearlescent brightener can vary widely, the main constraint on the upper limit is viscosity.

The amount of pearlescent brightener should not be so high as to render the product unpourable or unacceptably viscous. We prefer from an economic standpoint that the pearlescent brightener is present in a higher amount than the suspending surfactant. Generally, pearlescent brighteners are present in an amount of from 5% to about 60% by weight of the total weight of the mixture, eg 10 to 45% by weight.
, More preferably 15 to 30% by weight, in particular 18 to 28% by weight. The weight ratio of pearlescent agent to surfactant is preferably 0.6 to 2 (eg 1.2 to 1.3).

In principle, adjunct ingredients suitable for inclusion in toiletries can be included in principle, but are usually omitted to avoid overly constraining the customer with regard to their freedom of formulation. However, it is generally desirable to include small amounts of preservatives such as formaldehyde or other antibacterial and / or fungicidal actives.

The novel structured underlayer phase may be used to suspend solids other than pearlescent brighteners (eg builders such as zeolites or phosphates for use in detergents). They may also suspend bentonite or calcite. They may suspend rock chips and / or extenders for using drilling mud. They can suspend agricultural pesticides or dyes or pigments, dicalcium phosphate for use in toothpaste, or ammonium polyphosphate for flame retardants.

The invention is illustrated by the following examples. The method consists of the following steps: i) Add water and heat to 75-80 ° C. ii) Add NaCl and dissolve with mixing. iii) Add 80-90% of SLES charge and mix until homogeneous. iv) Add EGDS and mix until a homogeneous emulsion is formed. 0.5 ~
Stir for 1.0 hour to ensure EGDS is dissolved. v) Initiate a cooling cycle to ensure that the emulsion is approximately 60-100 rpm (8
Stir well at 0 rpm). vi) Once the product has cooled to 30-35 ° C, add the rest of SLES and mix until homogeneous. vii) Check the solids and adjust with water to the following specifications. viii) Add preservatives and adjust pH accordingly.

[0028]   The concentrate requires the following cooling cycle.

[Table 1] It was found that the concentrate prepared using the method described above had a consistent pearl size (20-40 microns), was stable to freeze / thaw and did not separate after 1 month at 40 ° C.

[0029]     [Example 1]

[Table 2] Appearance: White / off-white metallic pearls pH (100%): 5.5-6.5 Odor: Characteristic Solids: 46-48% (typical) Viscosity (25 ° C): less than 20000 cps Density (20 ° C ): 0.95 to 1.05 gcm ^-3

[0030]     [Example 2]

[Table 3] Appearance: White / off-white metallic pearls pH (100%): 5.5-6.5 Odor: Characteristic Solids: 40-42% (typical) Viscosity (25 ° C): less than 20000 cps Density (20 ° C ): 0.95 to 1.05 gcm ^-3

[0031]     [Example 3]

[Table 4] Appearance: White / off-white metallic pearls pH (100%): 5.5-6.5 Odor: Characteristic Solids: 51-54% (typical) Viscosity (25 ° C): <10,000 cps (typically) ) Density (20 ° C): 0.95 to 1.05 gcm ^-3

[0032]     [Example 4]

[Table 5] Appearance: White / off-white metallic pearls pH (100%): 5.5-6.5 Odor: Characteristic Solids: 57-60% (typical) Viscosity (25 ° C): <10,000 cps (typically) ) Density (20 ° C): 0.95 to 1.05 gcm ^-3

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) B01F 17/42 B01F 17/42 C11D 1/14 C11D 1/14 3/04 3/04 3/20 3 / 20 17/08 17/08 (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR BY, BZ, CA, CH, CN, CR, CU, CZ, DE, DK, DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN , IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (72) Invention Person Hawkins, John United Kingdom, South Stuff Diwai 7.6Ag, Kimber, Chandler Avenue 21F Term (reference) 4C083 AB031 AB032 AC391 AC392 AC781 AC782 CC23 CC38 DD02 DD23 DD27 EE06 FF05 4D077 AA09 AB11 AC05 BA02 BA03 DC14Y DC19Y DC54Y DD29Y DE0 2Y DE07Y DE29Y 4H003 AB31 BA12 DA02 EA19 EB09 ED02 FA13

Claims (6)

[Claims] 1. Use of an aqueous lamellar surfactant for suspending solid particles. 2. Use according to claim 1 of a raw layered aqueous surfactant for suspending pearlescent brighteners. 3. A composition comprising suspended particles of an original layered aqueous surfactant and a pearlescent brightener. 4. Optically anisotropic properties when water, alkali metal, ammonium or C _1-6 amine salt of C _10-18 1-10 mol ethoxysulfate, 17-30% by weight, is exposed to shear with said sulfate and water. And sufficient electrolyte to form an optically isotropic phase exhibiting layered symmetry, 15-6 particles of ethylene glycol mono and / or distearate having a particle size of 6-60 microns suspended in the composition.
A composition containing 0% by weight. 5. 19 to 28% by weight of water, 1 to 5 mol of C _12-14 alkyl sodium ethoxysulfate, at least predominantly composed of ethylene glycol distearate, optionally with a small proportion of ethylene glycol monostearate. 18-28% by weight of a pearlescent brightener consisting of a mixture of
And a composition containing 2 to 5% by weight of sodium chloride. 6. The 18-28 wt% of C _{10 to 18} alkyl 1-10 Moruetokishi solution of sodium sulfate and 2 to 5% by weight of sodium chloride, an emulsion of ethylene glycol distearate, optionally 6. Forming an emulsion of a mixture with a small proportion of ethylene glycol monostearate at a temperature above its melting point and cooling said emulsion. A method for producing a pearlescent brightener suspension according to.