search.noResults

search.searching

dataCollection.invalidEmail
note.createNoteMessage

search.noResults

search.searching

orderForm.title

orderForm.productCode
orderForm.description
orderForm.quantity
orderForm.itemPrice
orderForm.price
orderForm.totalPrice
orderForm.deliveryDetails.billingAddress
orderForm.deliveryDetails.deliveryAddress
orderForm.noItems
FORMULATING FOR MILDNESS 75 between the molecules.4 For acyl


sarcosinates, however, this is not possible (Fig 3). In the following some of the consequences are described. Amino acid surfactants are produced via


a two-step synthesis route starting from fatty acid. This process leads to a salt content of 5% and more in customary 30% amino acid surfactant solutions. Additionally, these solutions contain unreacted free amino acid. For some consumer products, however, a high purity grade is required. The reasons, for instance, can be reduced stabilities of ‘salty’ products or unwanted colour reactions of the free amino acid with other ingredients (e.g. essential oils). Some customers therefore prefer a limited content of salt and free amino acid of maximum 0.5% or even lower. For the purification process the melting point of the protonated amino acid surfactant plays a major role. For protonated lauroyl sarcosinate (lauroyl sarcosine) the melting point is about 50°C whereas for lauroyl glycine and lauroyl glutamic acid it is about 120°C and 100°C.5 Protonated amino acid surfactants which are liquid at a temperature below 80°C – 90°C enable an easy purification step. So, this is only possible for lauroyl sarcosinate. As a consequence, commercial aqueous lauroyl sarcosinate solutions often have a low salt concentration. In contrast to this, there are only very few suppliers for highly pure cocoyl glycinate and cocoyl glutamate solutions on the world-wide market. To desalt them a more sophisticated procedure is necessary. Another significant difference between


the lauroyl derivatives of sarcosine and glycine is their solubility. Additional intermolecular hydrogen bonds stabilise the solid acyl glycinate form which reduces the water solubility. A suitable measure to prove this is the Krafft-temperature. It informs about the minimum temperature above which surfactants are water-soluble. For sodium lauroyl glycinate it is above room temperature even in weakly alkaline solutions.6


In contrast, sodium lauroyl


sarcosinate is easy to handle in aqueous solutions. At pH 7.5 the deprotonated anionic form is predominant 2,7


and the


Krafft-temperature is below room temperature. Sodium lauroyl sarcosinate is soluble even in cold water and in slightly acidic solutions. In a solution of the soap sodium laurate, on the other hand, at pH 7.5 already 50% of the soap is turned into water-insoluble lauric acid. This confirms the statement that sodium lauroyl sarcosinate is the “better soap“.2 The different behaviour of acyl


sarcosinates and acyl glycinates can also be seen in the viscosity of their 30% aqueous solutions. Whereas the viscosity of sodium cocoyl sarcosinate solutions is water-like, the


November 2020 Acyl glycinate O O


N H


O- O O


N H


O- O O N O-


Figure 3: Two amino acid surfactants: Hydrogen bonds (hashed line) can be created only in acyl glycinates.


Disordered micellar structures: Low viscous Ordered structures: Viscous N O- Acyl sarcosinate O O


Protonation of acyl sar- cosinate/acyl glycinate


Hydrophilic surfactant part Hydrophobic surfactant part


Figure 4: Radical change of micellar structures: Thickening by lowering the pH.


viscosity of sodium cocoyl glycinate solutions can be in the range of several thousand mPa∙s. Therefore, already in the production process problems can arise. Also, for some applications (highly) viscous cocoyl glycinate solutions are difficult to handle. Two very effective measures to reduce the viscosity of cocoyl glycinate solutions will be suggested when Zschimmer & Schwarz products are introduced. The capability of acyl glycinate to create


intermolecular hydrogen bonds also has advantages. By these bonds, the stability of foam in comparison to acyl sarcosinate is enhanced.4


It was shown that via


intermolecular hydrogen bonds the foam lamella elasticity is increased.8


This means


that the bursting of foam bubbles is slowed down. In cosmetic applications consumers often perceive stable foam as a very creamy foam. The stabilisation of foam by intermolecular hydrogen bonds is a general phenomenon.9


its ultra-mildness, which is proven in clinical tests.10


In addition, the preferred pH-range


to use acyl glycinates is the neutral to alkaline pH-range. These facts turn cocoyl glycinate into an ideal candidate for pH-neutral baby care applications as their skin has a pH of about 7. As shown later in a frame formulation, by adding suitable co- surfactants clear formulations can also be created in a pH-range of about 6.


In cosmetic products normally


mixtures of different surfactants are used. Acyl glycinates with their ability to create hydrogen bonds are a smart choice to create a creamy foam also in surfactant mixtures. A unique property of cocoyl glycinate is


Acyl glutamates: completely sustainable With a longer carbon chain and an additional carboxylate group the derivatives of glutamates (Figs 1a,2a) have some different properties than acyl glycinates and acyl sarcosinates. In the production process the additional carboxylate group leads to side-reactions which reduce the yield of the target product. To avoid this, surfactants based on acidic amino acids like acyl glutamates usually are synthesised in aqueous solutions to which a solvent is added. This was already recommended in the patent of the 1930s.1


When the solvent is volatile like acetone it is removed afterwards to avoid PERSONAL CARE ASIA PACIFIC


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96