Formula design

In the development of cosmetics, formula design is crucial, because the scientific design of the formula will determine the quality of the product, it is the core of cosmetic technology. Therefore, the product formula of cosmetics has a mysterious color in the cosmetics industry, and each company regards the formula of the product as the technical secret of the enterprise to protect it. For the scientific and rationality of cosmetic formulas, according to the quality characteristics of cosmetic products, the following principles should be followed and paid attention to in the formulation design of cosmetics:

1. Security is in the first place

Because cosmetics are daily necessities that people use daily, long-term, and continuous in their daily lives, their safety is considered the primary quality characteristic. The safety of cosmetics refers to the non-toxic (oral toxicity), non-irritating and non-allergic to the skin (hair) and eye mucosa. When selecting raw materials for cosmetic formula design, we must follow China's cosmetics hygiene regulations, do not use and do not contain cosmetics banned raw materials, when using limited raw materials, we must abide by the dosage regulations, and must not exceed China's limit on toxic substances.
    Limiting toxic substances, arsenic, mercury, lead, methanol and various raw materials in cosmetic raw materials is very important, because in the production process of some raw materials, some heavy metals will be brought in due to factors such as equipment and environment. These harmful elements are absorbed by the skin through the skin and then accumulated in the liver through the blood circulation to induce body lesions. China's cosmetics and beauty industry must pay attention to and abide by the standards promulgated by the state, and cannot ignore the short-term interests of enterprises.

2. Stability as a focus

At present, the quality problems of Chinese cosmetic products during the shelf life are mainly manifested in two aspects: one is the health and safety of microbial contamination; the other is the product is characterized by water separation, oil deposition, stratification, sedimentation, discoloration, odor and swelling. Stability issue.
The main reason for the instability of the product is that the formulation design is not reasonable, so the product stability is the key content of the formula design. Such as the general cream (emulsion) cosmetics formula composition is diverse and complex, in addition to oil, water phase raw materials, as well as a variety of efficacy additives, preservatives, flavors and pigments, etc., is a multi-phase dispersion system. In theory, it is a thermodynamically unstable system, but it has dynamic stability as well as power stability and other stability factors, so that it has a relative stability or a metastable state, which can be maintained during the shelf life. purpose. The main factors affecting the instability of emulsion products are:

2.1, the choice of emulsifier

The most important choice for the design of the emulsion formula is the choice of emulsifier. Generally, the emulsifier can be selected according to the type of emulsification method. The emulsification method is constantly developing, and it has a reactive (soap-based), non-reactive, liquid crystal, and Emulsifying methods such as resistive and ultrafine emulsification. Non-reactive emulsification is usually used. This emulsification method does not require alkali, and the emulsification is accomplished by rational compounding of various surfactants. The hydrophilic or lipophilic properties of the nonionic or high molecular polymer surfactant and the formation of a bimolecular adsorption layer or a liquid crystal structure network stabilize the emulsion system. Therefore, after the formulation, matrix and raw materials of the product are determined, the choice of emulsification mode and emulsifier is very important, which should be regarded as the focus of formula design, which plays a decisive role in the stability of the emulsion.

2.2, the influence of medium viscosity and dispersion

 In studying and discussing the stability of emulsion systems, there is the famous Stokes equation:
v=2rr(p2-p1)×g / 9η
In the formula: the sedimentation rate of the particle factory in the v-system
Medium viscosity in η-system
Radius of the particles (drops) in the r-system (r in this formula represents the second power of r)
G-gravity acceleration,
P1 and p2 are the density of the inner phase and the outer phase, respectively.
    The sedimentation velocity v in the formula is the aggregation velocity of the particles (drops) in the system. Obviously, if the aggregation velocity η is large, the internal phase (oil phase or water phase) of the system is easily aggregated to cause oil and water separation and instability. Therefore, the smaller the sedimentation speed, the more stable the cream or emulsion system is; the formula can be concluded: when the internal phase and the external phase of the system, that is, the density difference (p2-p1) between the oil phase and the water phase is smaller, the system becomes more Stable; when the particles (drops) of the system are smaller, that is, the smaller the v, that is, the finer the oil droplets or water droplets are dispersed, the smaller the v is, and the more stable the system is. Therefore, in the preparation of emulsions, high-efficiency emulsification equipment should be used, the rotation speed is above 3000 rpm, the dispersion of the system is high, the stability of the product is good, and the appearance is bright and delicate; the viscosity of the system medium (ie, the external phase) is settled in the formula. The velocity v is inversely proportional to η, that is, the greater the viscosity η of the outer phase, the smaller the v, the more stable the system. When an O/W cream is prepared, the stability of the cream can be improved by adding a hydrophilic polymer compound to the external phase (aqueous phase) to thicken.

3, compatibility is the key

  Cosmetics are not products of chemical synthesis reactions, but products that are compounded from a number of components by appropriate process mixing. A product sometimes uses more than 20 kinds of raw materials, so the compatibility between the components is a key to the design of the selected components, because it can not only affect the final quality and characteristics of the product, but also determine whether the product is stable. The compatibility of the components in the formulation is good, there is no chemical reaction between each other, and there is synergy, and the formulation can be considered reasonable.
    There are nearly 10,000 kinds of raw materials for cosmetics, which are commonly used, and there are more than 3,000 kinds. In order to make the components in the formula have good compatibility, it is important to have a full understanding of the physical and chemical properties of various raw materials. Pay attention to the compatibility between raw materials, contraindications and mutual solubility and pH range.


4, the efficacy should be fully reflected

Each kind of cosmetics has its specific effects and usefulness, showing its usefulness in physicochemicals: covering, cleaning and moisturizing; biological effects: anti-wrinkle, whitening, etc.; in addition, due to color, aroma and other psychology The effectiveness of learning. At present, 9 types of special-purpose cosmetics in China have more specific effects. In the design of cosmetic formulas, it is necessary to add appropriate amounts of functional ingredients, and should be tested for effects, such as several levels of moisturizing effect. It should be consistent with the efficacy indicated by the product, otherwise it can be regarded as a deceptive behavior to consumers. In the future, China's efficacy testing for special-purpose cosmetics should be gradually quantified. For example, the effect of weight loss can be evaluated by ultrasonic measurement of fat layer thickness, which inevitably requires more scientific and rigorous formulation of functional cosmetics.




5, the sensory effect can not be ignored (use sense, ease of use)




Cosmetics is a daily chemical that beautifies the human body and should reflect certain cultural connotations and artistry. Consumers intuitively demand that it have a good look and feel. Whether the cosmetics are here, the cream products need to be pleasant, delicate, smooth and soft, and have good applicability and spreadability. These sensory effects are closely related to the variety and amount of oily ingredients in the formulation and their physical and chemical properties (refractive index, viscosity, etc.), such as commonly used low viscosity dimethicone, cyclic volatile silicone oil, isoparaffin and The isomerized esters have a feeling of oil but not greasy. The pros and cons of the product formula are firstly expressed in the sensory effect. Even if it has good effect, it is difficult for consumers to accept because of its dark color, thick paste and odor. Especially Chinese herbal cosmetics should pay attention to this point.




6, practical and operability must take into account




When designing the formulation and production process of cosmetics, it is necessary to consider the feasibility of the formulation in actual production, and try to make it convenient in production operation.




7. Price costs need to be accounted for and evaluated (economic)




At present, the ratio of the cost price to the performance of the product is often used as an indicator for evaluating the formulation level of the cosmetic product. When the ratio of cost to performance is smaller, that is, the lower the cost of the product, and the better the performance of the product, indicating that the product is The higher the formula design level. Therefore, when designing a cosmetic formula, it is necessary to calculate the cost of the formula according to the price of each component in the formula, and further improve the formula to obtain a high-performance product by using a low-cost cost. This should be the pursuit of formulators.