Rheological Additives in Cosmetics

Transcription

1 Rheological Additives in Cosmetics pure in cosmetics

2 Contents Introduction 2 Cosmetics and Rheology 4 Rheological Additives for cosmetics 6 Aqueous-Phase Additives 7 Rheoluxe Associate Thickeners 7 Hectorite - The Benefits 8 BENTONE Hydrophilic Clays 8 Non-Aqueous-Phase Additives 10 BENTONE Organophilic Clays 10 BENTONE GEL 11 THIXCIN R Rheological Additive 13 Product Application and Selection 14 Incorporation & Equipment Guideline 15 INCI References 16 Personal Care Skin Care Sun Care Decorative Cosmetics Today s successful cosmetics products need the right rheological properties. And the correct choice of rheological additive enhances the product in production, storage stability and application. rheological additives for aqueous and non-aqueous formulations are valuable and proven tools for you to use. Personal care, skin care, sun care and decorative cosmetics; single-phase, suspension or emulsion; all can benefit from rheological additives. RHEOLUXE BENTONE BENTONE GEL NANOX THIXCIN are trade names of pure in cosmetics

3 Cosmetics and Rheology Strong partners to create the best possible products Rheology is the science of flow. Every time a lotion is poured, a cream squeezed from a tube or a lipstick applied, rheology is involved. Even when products are at rest, it plays an important part in controlling stability and suspension. Understanding a formulation s rheological needs enables you to create the best possible products. The way the viscosity changes at varying shear rates greatly influences the overall product stability and performance. A material which maintains a constant viscosity, regardless of shear rate, has Newtonian flow (Fig.2). Dilatant flow (Fig.2) is a form where viscosity increases with shear, sometimes encountered in highly pigmented/filled systems. Pseudoplastic flow (Fig. 4), also known as shear thinning behaviour, and typical of many commercial systems, is when viscosity decreases with increasing shear rate. Flow may require a specific stress to be initiated. This particular stress value is known as the yield point. A system having both shear thinning flow and a yield point can be described as having plastic flow. The rate of recovery of a system when stress is removed is also very important. When a shear thinning system shows delayed viscosity recovery, it is described as thixotropic (Fig.3). This is one of the most important types of flow in cosmetics. Controlling the degree of thixotropy enhances the application of a cream, eliminates dripping of a roll-on antiperspirant or allows brushmarks in a coat of nail lacquer to disappear, leaving a smooth film. Viscosity can be temperature dependent. Correct choice of rheological additive allows you to create the ideal flow characteristics (Fig. 1) and also achieve thermostable rheology. The rheology of a system is described in terms of its viscosity. Viscosity is the resistance to flow and defined as: Shear stress is the force per unit area applied and shear rate is the resulting velocity gradient. Cosmetics experience shear rates varying from s-1, from gravitational forces; to over 20,000 s-1, when a cream is spread or an aerosol antiperspirant sprayed (Fig 1). 5

4 Aqueous-Phase Additives Rheoluxe Associative Thickeners The Rheoluxe family of rheology modifiers are nonionic polymeric thickeners designed specifically for the personal care market. Rheoluxe consists of Urethane based and Polyether Polyol based associative thickeners with superior performance in difficult systems such as those containing high salt levels or with extremes in ph. Due to its structure, Rheoluxe is soluble in water, but associates with lipophilic materials to build viscosity. Associative thickeners mechanism of action Associative thickeners increase the viscosity of aqueous systems through a system of molecular associations and interactions. The thickeners consist of water soluble polymeric chains modified with hydrophobic caps. The hydrophobic caps of the polymer associate, that is build a structured network with other hydrophobes in the formula. This results in micelle type structures that form a network resulting in significant viscosity build. Associative thickeners Mechanism of action Rheoluxe structure Hydrophobic Cap Hydrophilic Chain Hydrophobic Cap Rheological Additives for Cosmetics Improving aqueous, anhydrous and emulsion-based products rheological additives can be broadly divided between aqueous-phase thickeners and non-aqueous-phase thickeners. But it is important to remember the advantages of oil-phase viscosity modification that can greatly improve emulsion based products. additives for cosmetics are based on naturally occurring materials: highly refined and beneficiated hectorite clay or castor oil derivatives. Rheoluxe 812 The Rheoluxe range of products provides viscosity control in all types of emulsion systems, creating an exceptional sensory profile. Supplied as easy to handle solutions, Rheoluxe can be added at any point in the production process. Rheoluxe is heat stable, although cold process systems are possible. INCI Name Typical use level: Chemistry Bis-Lauryl Cocaminopropylamine/HDI/PEG-100 Copolymer (and) Butylene Glycol % Polyurethane Rheoluxe 880 Bis-C16-20 Isoalkoxy TMHDI/PEG-90 Copolymer % Polyurethane Rheoluxe 8015 PEG/PPG-450/50 Trimethylolpropane Dodecyl Ether % Polyether Polyol 7

5 Non-Aqueous-Phase Additives Hectorite - The benefits Hectorite is a unique swelling clay offering several advantages. Hectorite s special properties, compared with bentonite, are: lower iron content lighter colour higher swelling capacity greater gel strength no crystalline silica Due to its small size, platelet shape and large surface area, hectorite is able to form strong, stable viscous gels. The two products are stable across the range ph 6-11 and offer good tolerance to electrolytes. BENTONE LT forms a similar network, but it is strengthened by the presence of a special cellulose, greatly enhancing stability and thickening characteristics. BENTONE LT is stable across a broader range, ph 3-11, and is also the least electrolyte-sensitive product. BENTONE MA and EW are in compliance with ECOCERT; The ecological and organic cosmetics standards. BENTONE rheological additives are non-abrasive. The skin feel imparted by BENTONE hydrophilic clays is a pleasant silkiness, quite different to that associated with the majority of cellulose, polymer and polysaccharide-based thickeners. Furthermore, as hectorite itself is insensitive to temperature variations, the BENTONE products impart a thermostable viscosity control. Surfactants can influence the rheological behaviour of hydrophilic clays. Non-ionic surfactants, if they are highly ethoxylated, can adsorb onto the clay surface. This rarely causes problems either in flow control or activity of the formulation. Anionic surfactants can act as dispersing agents and weaken the gel structure. Alternatives that eliminate or minimise any problems can normally be found. BENTONE Organophilic Clays Hectorite is now reacted with special vegetable quaternary ammonium salts to produce organoclays able to thicken and gel organic liquids. The correct choice of BENTONE additive is determined largely by the polarity of the system to be thickened. Additive BENTONE 27 V BENTONE 38 V Application Intermediate to high-polarity organic systems such as esters and triglycerides - for nail lacquers, skin care, antiperspirants and lip products Low to intermediate-polarity organic systems such as volatile silicones and mineral oil - for antiperspirants, creams, lotions, eye products and suntan products However, cationic surfactants interact strongly and should be avoided. Hectorite is a very effective thickener of water. Because of this and its other exceptional properties, it forms the basis of the BENTONE hydrophilic clays. BENTONE Hydrophilic Clays BENTONE MA, EW, and LT rheological additives provide thixotropy and suspension control to the aqueous phase. BENTONE MA and EW additives form gels by producing an open, 3-dimensional network of the individual clay platelets as shown in Figure 5. INCORPORATION Hydrophilic Clays Wetting Medium to high-shear mixing Add clay to water before addition of other ingredients Disperse at moderate ph Shear Low shear (< 10 ms-1) = long mixing time (> 30 mins) High shear (> 15 ms-1) = shorter mixing time (10-15 mins) Time 10 minutes hydration before adding other ingredients Heat Water at up to 60 C (140 F) reduces hydration time It is important to have only unadulterated water present at the dispersion stage. Surfactants or electrolytes should not be added until dispersion is completed For additional guidance see page 14 Organic and silicone-based liquids used in oil and wax-based cosmetics, and as the non-aqueous-phase in emulsions, benefit greatly from rheological additives. Outstanding rheological properties are developed using BENTONE organoclay rheological additives in their powder form or, even better, with BENTONE GEL additives, their predispersed forms. The benefits gained are: thermostable viscosity control thixotropic flow suspension control of pigments and actives emulsion stabilisation silky skin feel 8 9

6 INCORPORATION BENTONE additives need to be efficiently dispersed using high-shear equipment and then to be activated with the optimum level of a chemical activator, such as propylene carbonate. BENTONE organoclays form thixotropic gels by developing hydrogen bond bridges between the edges of adjacent platelets as shown in Figure 7. BENTONE GEL BENTONE GEL additives are optimally dispersed and activated predispersions of organoclays. Benefits include: optimally dispersed high-shear dispersion not necessary no polar activation required easy to handle and use can be added at any appropriate and convenient stage in manufacture A wide range of gels made from various cosmetics oils, esters and solvents are available. The use of a BENTONE GEL enables you, the formulator, to achieve the maximum efficiency from the organoclay without the need for careful shearing and activation. On the production scale, time is saved and the highest degree of reproducibility attained, leading to potenial cost savings. BENTONE GEL additives can be added at any convenient suitable stage in the manufacturing cycle. BENTONE GEL additives are very high-viscosity, shear thinning products. To ensure good homogeneous mixing is achieved, care must be taken to overcome large viscosity differentials existing between the BENTONE GEL and the other lower-viscosity components. Choice of mixing equipment and the configuration within the mixing vessels are critical factors in developing the optimum performance of the BENTONE GEL additive. The use of medium- to high-shear mixing equipment is recommended. For additional guidance see page 14 Batch Processing Single-Phase Systems Always add the BENTONE GEL, under shear, to a portion of the organic component or solvent with which it is most compatible. Mix until homogeneous before adding the other ingredients. Multi-Phase Systems (eg. emulsions) As for the single phase, but always ensure the BENTONE GEL additive is thoroughly mixed in before the emulsification stage. Continuous processing The BENTONE GEL should be added to the oil phase at any convenient point that meets the above guidelines for the batch processing. In multi-manifold systems, a flowable pre-mix of the BENTONE GEL with a compatible oil or solvent should be made in a side pot. Where only lower-shear mixing equipment is available, stir the BENTONE GEL alone, in a small mixing vessel, if necessary, and then slowly add the most compatible component by portions, always ensuring the mixture is homogeneous at each stage

7 THIXCIN R Rheological Additive For the highest degree of thixotropy in aliphatic liquids, THIXCIN R additive is the product to use. In addition to its effective rheological properties, it gives water repellency, stabilises emulsions and acts as a stiffening agent in lipsticks and ointments. It can also be used as a dry binder in pressed powder systems. (Where high-temperature resistance is needed, BENTONE or BENTONE GEL additives are recommended). THIXCIN R is a castor oil derivative. It requires temperature-controlled activation within the range C ( F) and high-shear mixing to develop its full structure. THIXCIN R is in compliance with ECOCERT; The ecological and organic cosmetics standards. INCORPORATION THIXCIN R additive Wetting High-shear mixing Add THIXCIN R to oil Disperse to deagglomerate Heat Temperature range C ( F) Shear Shear for 20 minutes within this temperature range to activate Cool Maintain shear to below 35 C (95 F) when cooling For additional guidance see page 15 pure in cosmetics Product Application and Selection Choosing the right rheological additive Cosmetic products range from pressed dry powders to suspensions in liquids; from single-phase solid or liquid formulations to emulsions. The choice of rheological additive and level of use depends on the system and the desired performance criteria (Table pages 20/21). The properties imparted by the rheological additive benefit different cosmetics in different ways. The advantages of using ELEMENTIS Specialties rheological additives are not always only the obvious ones, for instance: Stick products (lipstick and antiperspirant) maintain homogeneity in molten and setting stages gain improved pay-out increase high-temperature integrity eliminate oil migration reduce creasing around lips and eyes Mascara improve film-build increase water-resistance eliminate oil migration Emulsions elevate drop-point temperature of water-in-oil creams eliminate syneresis improve emulsion stability enable cold-process emulsification create novel viscosity effects UV Sunscreen eliminate ultrafine Ti02 skin-whitening problems enhance sun protection factor (SPF) optimise use of sunscreen actives reduce separation and settlement Antiperspirant Aerosols uniform distribution of active ingredients soft and dry skin feel significant less whitening reduced separation and settlement 13

8 Incorporation & Equipment Guideline INCI References Trade Name INCI Name Shear Development Low Low Medium Med-high Med-high Very high Generic Type Paddle Propeller Planetary Rotor/stator Impeller Homogeniser BENTONE MA, BENTONE EW and BENTONE LT additives powders needing high-energy mixing Conditions Suitable only for Suitable for BENTONE MA, EW, LT additive Suitable for BENTONE EW additive BENTONE Use highest speeds Use highest speeds and carefully MA, EW, LT (> 3000 rpm). observe optimum mixer/vessel additives. configuration. Order of addition Clean water and rheological additive only. Avoid addition of surfactants or electrolytes until dispersion completed. Special factors BENTONE EW < 5 BENTONE MA <10% ph of water neutral. BENTONE EW < 5% Sift clay in gradually. Add BENTONE LT < 4% defoamers, if needed, only ph of water neutral. after dispersion completed. Sift clay in gradually. BENTONE 27 V and BENTONE 38 V additives powders needing high-energy mixing Conditions Unsuitable Suitable for BENTONE 27 V Recommended insufficient shear. and 38 V additives. for Use highest speeds and carefully BENTONE 27 V observe optimum mixer/vessel and 38 V configuration. additives. Order of addition N/A Oil or solvent alone. Add organoclay and disperse. Add polar activator and continue dispersing. Special factors N/A Ensure full wetting achieved before activation. Use optimum level of polar activator. Avoid the presence of surfactants until after activation. BENTONE GEL rheological additives optimally dispersed and activated gels Conditions Use maximum speed Use highest speeds and carefully Add gel to and dilute gel stepwise observe optimum mixer/vessel vessel, apply under shear. configuration. shear prior to Min. 10 > 1500 rpm. adding other ingredients by increments. Order of addition Gel first, then oil or solvent Add gel to portion of oil/solvent Add oil to in ratio 60:40 gel to oil. under shear. Maintain shear gel stepwise. Mix and add other until homogeneous. components in steps. Special factors Ensure mixture is Ensure mixture is homogeneous at each dilution stage. homogeneous at each Particulate materials, such as antiperspirant salts dilution stage until flowable will assist in the dispersion in low-viscosity media. consistency achieved. RHEOLOGICAL MODIFIERS FOR AQUEOUS-PHASE BENTONE EW Hectorite BENTONE EW CE Hectorite BENTONE LT Hectorite, Hydroxyethylcellulose BENTONE MA Hectorite RHEOLATE FX 1100 Steareth-100/PEG-136/HDI Copolymer NEW! RHEOLUXE 880 Bis-C16-20 Isoalkoxy TMHDI/PEG-90 Copolymer NEW! RHEOLUXE 812 Bis-Lauryl Cocaminopropylamine/HDI/ PEG-100 Copolymer, Butylene Glycol NEW! RHEOLUXE 8015 PEG/PPG-450/50 Trimethylolpropane Dodecyl Ether RHEOLOGICAL MODIFIERS FOR NONAQUEOUS-PHASE BENTONE 27 V Steraralkonium Hectorite BENTONE 27 V CG Steraralkonium Hectorite BENTONE 38 V Disteardimonium Hectorite BENTONE 38 V CG Disteardimonium Hectorite THIXCIN R Trihydroxystearin RHEOLOGICAL MODIFIERS FOR NONAQUEOUS-PHASE BENTONE GEL 1002 V Cyclopentasiloxane, Disteardimonium Hectorite, Propylene Carbonate BENTONE GEL ABO V Crambe Abyssinica Seed Oil, Stearalkonium Hectorite, Propylene Carbonate BENTONE GEL CAO V Ricinus Communis, Stearalkonium Hectorite, Propylene Carbonate BENTONE GEL EUG V Octyldodecanol, Disteardimonium Hectorite, Propylene Carbonate BENTONE GEL GTCC V Caprylic/Capric Triglyceride, Stearalkonium Hectorite, Propylene Carbonate BENTONE GEL HSO V Helianthus Annuus (Sunflower) Seed Oil, Disteardimonium Hectorite, Propylene Carbonate BENTONE GEL IHD V Isohexadecane, Disteardimonium Hectorite, Propylene Carbonate BENTONE GEL IPM V Isopropyl Myristate, Stearalkonium Hectorite, Propylene Carbonate BENTONE GEL ISD V Isododecane, Disteardimonium Hectorite, Propylene Carbonate BENTONE GEL LOI V Lanolin Oil, Isopropyl Palmitate, Stearalkonium Hectorite, Propylene Carbonate BENTONE GEL MIO V Mineral Oil, Disteardimonium Hectorite, Propylene Carbonate BENTONE GEL MSO V Limnanthes Alba (Meadowfoam) Seed Oil, Disteardimonium Hectorite, Propylene Carbonate BENTONE GEL NGD V Neopentyl Glycol, Diheptanoate, Disteardimonium Hectorite, Propylene Carbonate NEW! BENTONE GEL OLV V Olea Europaea (Olive) Fruit Oil, Stearalkonium Hectorite, Propylene Carbonate BENTONE GEL OMS V C11-12 Isoparaffin, Disteardimonium Hectorite, SD Alcohol Denat BENTONE GEL PTIS V Pentaerythrityl Tetraisostearate, Disteardimonium Hectorite, Propylene Carbonate BENTONE GEL PTM V Phenyl Trimethicone, Disteardimonium Hectorite, Triethyl Citrate BENTONE GEL SS71 V Petroleum Distallates, Disteardimonium Hectorite, Propylene Carbonate BENTONE GEL TMF V Methyl Trimethicone, Disteardimonium Hectorite, Triethyl Citrate BENTONE GEL TN V C12-15 Alkyl Benzoate, Stearalkonium Hectorite, Propylene Carbonate BENTONE GEL VS-5PC V Cyclopentasiloxane, Disteardimonium Hectorite, Propylene Carbonate BENTONE GEL VS-5V Cyclopentasiloxane, Disteardimonium Hectorite, SD Alcohol Denat Natural product 14 15

9 Before using any of our products please consult our Safety Data Sheets. The information in this publication is, to the best of our knowledge, true and accurate, but since the conditions of use are beyond our control, no warranty is given or to be implied in respect of such information. In every case, caution must be exercised to avoid violation or infringement of statutory obligations and any rights belonging to a third party. We are, at all time, willing to study customers specific outlets involving our products in order to enable their most effective use. Local representative Consumer Products EUROPE ELEMENTIS GmbH Stolbergerstrasse Cologne Germany Tel: Fax: consumer@elementis.com U.S. 469 Old Trenton Rd. East Windsor, NJ Tel: Fax: consumer@elementis.com Visit our website: pure in cosmetics