1. Industry background
Ester oils and silicone oils are two types of oil-phase raw materials that are widely used. Almost most moisturizing lotions, lightweight creams, makeup primer and other products will use the two together.
In simple terms, ester oils can bring a gentle and moisturizing effect to the lotion, solving the problem of dryness and insufficient moisturizing power of the product, while silicone oils can optimize the spread of the product and create a popular dry skin feeling on the market.The interaction of the two can not only achieve a good film-forming moisturizing effect, but also ensure that the upper skin is light and malleable, and it is suitable for daily skin care, base makeup and other use scenarios.
2. Essential differences in raw materials
The contradiction between the adaptation of ester oils and silicone oils is rooted in the different molecular structures of the two and the different basic physical and chemical properties, which also determines their different modes of action and interface performance in the emulsion.
Ester oils are organic polar Emollients. The commonly used raw materials such as pentaerythrityl tetraisostearate and isononyl isononanoate on the market have distinctive raw material characteristics, which are also the core advantages of their adaptation to the emulsion system.
Core characteristics of ester grease：
-The molecule has an ester-based functional group and has medium polarity
-Strong intermolecular force, good grease structure stability
-Excellent compatibility with hydrocarbon oils and similar ester raw materials
-Good moisturizing, film-forming, and pigment dispersion ability
Like the high-molecular-weight pentaerythrityl tetraisostearate, it not only has excellent moisturizing and sealing properties, but also has a good waterproof effect, which can improve the adhesion and gloss of the emulsion. It is the core raw material in the emulsion system that supports the skin feeling and efficacy, and it is also the skin feeling skeleton of the entire emulsion system.At the same time, adding an appropriate amount of Ascorbyl palmitate to the formula can also work synergistically with ester oils to enhance the oxidation resistance of the oil phase and delay the oxidation and deterioration of the oil.
Silicone oil is an inorganic flexible chain raw material. Dimethicone crosspolymer, Dimethicone crosspolymer, etc., which are frequently used in market formulas, have different physical and chemical properties from organic ester oils.
Core characteristics of silicone oil：
-With silicon-oxygen bonds as the core molecular skeleton, it has the characteristics of inorganic raw materials
-Extremely low surface tension and excellent spreading performance
-High molecular chain flexibility and outstanding ductility
-The overall polarity is very low, and it is an ultra-weakly polar oil phase raw material
The biggest advantage of this kind of raw material is that it spreads quickly, there is almost no sticky residue on the skin, it can create the ultimate dry touch, and volatile silicone oil can evaporate quickly, further enhancing the lightness of the product.
3. Three common states of existence of ester-silicon mixed oil phase
In the process of blending the oil phase of the emulsion, the two types of raw materials will show three different structural states after mixing. The different states directly determine the stability of the emulsion and the final skin feeling. The most common in daily formulas is the state of microscopic phase separation, but the stable state of complete miscibility is relatively rare.
The first is a completely miscible state, which mostly appears in the system of light ester oils and low molecular weight silicone oils, and it is also the most ideal oil phase state in formula development.
Core characteristics of this state：
-The two types of grease can be partially miscible, and there is no obvious phase difference.
-Form a uniform and unified complete oil phase system
-The overall stability of the emulsion is excellent, and the storage is not easy to go wrong
-The upper skin feels uniform and delicate, without local heavy and dry blemishes
This stable system is mostly used in low-viscosity skin care products such as lightweight essences and refreshing water creams.，
Suitable for daily refreshing skin care scenes.
The second is the microscopic phase separation state, which is the mainstream form of most esterosilicate complex emulsions on the market, and it is also the most common system state in the formula.
Core characteristics of this state：
-The two phases of ester silicon cannot be completely miscible, forming nanoscale microscopic partitions
-With ester grease as the continuous phase, silicone oil gathers to form a tiny enrichment area
-The microscopic separation structure is not visible to the naked eye, and there is no obvious stratification phenomenon
-The system is in dynamic balance, there is no abnormality in appearance but there are hidden fluctuations in skin feeling
This hidden microstructure change is the core reason why many lotion products are smooth and dry when they are first applied to the skin, and the texture of the skin deteriorates and the skin feels unstable after absorption.
The third is the macroscopic phase instability state, which belongs to the failure state caused by formula design errors and improper matching of raw materials, and belongs to the unqualified emulsion system.
Core characteristics of this state：
-The two phases of ester silicon have obvious macroscopic phase separation, and the uniformity of the system is completely destroyed.
-Tiny oil droplets continue to gather and merge to form a large-particle oil phase
-The emulsion has obvious problems such as oil, sweating, and layering
-The texture of the product is broken and the texture of normal use is completely lost
Most of this failure state is caused by unbalanced ester-silicon ratio, mismatched emulsification system, incorrect selection of raw materials, etc., and the finished product cannot be produced and sold normally.
4. Skin sensation formation mechanism of different ratio systems
The difference in skin feeling of emulsions felt by consumers is essentially the result of different ratios of ester oils and silicone oils and different phase structure distributions. There is a very obvious difference in skin feeling performance between the two types of raw material-led systems.
The emulsion system dominated by ester oils has a warm and plump overall skin feeling, which is suitable for moisturizing skin care products, mainly for dry skin.
Skin feeling characteristics of the ester-led system：
-Smooth and soft application, with a soft waxy cushion to the touch
-The oil absorption speed is moderate, it will not dry out quickly and it will not be sticky.
-Good film-forming properties, excellent moisturizing and battery life
-Long-lasting skin moisture, suitable for dry environments in autumn and winter
The reason for this skin feeling is because the molecules of ester oils have stronger cohesion. During the application and rubbing process, the oil phase structure will be broken in an orderly manner and spread evenly, which can form a uniform moisturizing film on the surface of the skin and nourish the skin for a long time.
The silicone oil-led lotion system focuses on refreshing and matte skin feeling, and is suitable for summer skin care and oily skin. It is a popular light-feeling lotion system at the moment.
Skin feeling characteristics of the leading system of silicone oil：
-The upper skin is instantly smooth, malleable and full, and it is easy to push away
-Almost no greasy residue, light skin feeling and no burden
-After absorption, the skin appears in a refreshing and matte state, not stuffy
-Volatile silicone oil evaporates quickly to eliminate the problem of sticky rubbing mud
This is based on the extremely low surface tension of silicone oil, which can achieve rapid spreading. With the rapid volatilization characteristics of volatile silicone oil, it can quickly take away the sticky feeling of the surface and create a dry skin feeling that the public loves.
The mainstream complex ligand system on the market is not a simple oil superposition, the core is to balance the flow activity and interfacial stability of the oil phase.Ester oils make up for the shortcomings of dryness and insufficient moisturizing of silicone oils. Silicone oils neutralize the heavy stickiness of ester oils. The two counterbalance each other and complement each other's advantages in order to create a balanced skin feeling that takes into account smoothness, moisturizing power, and freshness. This is also the core reason why the ester-silicon complex ligand system can become the mainstream of the industry.
5. Emulsification system regulation
In formula research and development, it is necessary to rely on the scientific Emulsifier makeup matching logic, and customize the appropriate emulsion system according to the ratio of ester silicon and the molecular weight characteristics of the raw material.For the system of polymer ester grease with crosslinked silicone oil, it is necessary to choose emulsified components with both ester- and silicon-friendly properties, build a stable oil-water interface film, and firmly wrap the two oil-phase raw materials with different characteristics to avoid phase separation.
Combined with the industry's mature formulation experience, the ester system with pentaerythrityl tetraisostearate as the core can be used as the skin-feeling skeleton of the emulsion, providing stable film-forming, moisturizing, and adhesion properties. It is used with volatile silicone oil and siloxane crosslinked polymer to optimize skin feeling, and then reconcile the two-phase adaptability through a dedicated emulsifying system.
Hubei Mingya New Material Technology Co., Ltd.
