The materials used in cosmetic packaging are usually glass, metal and plastic. Plastic materials have become the main material of cosmetic packaging due to their low price, easy processing, and suitability for mass production. At present, plastic packaging occupies more than 70% of the cosmetics market.
With the application of biodegradable materials in many fields, the research on biodegradable cosmetic packaging materials has attracted the attention of researchers. The promotion of safe and biodegradable cosmetic packaging materials has become one of the future development directions of the cosmetic packaging industry.
Status Quo of Biodegradable Materials in Cosmetic Packaging Field
At present, biodegradable cosmetic packaging materials can be used for rigid packaging of cosmetics such as creams and lipsticks. Due to the particularity of the cosmetic itself, it is not only required to have a unique appearance, but also a package that meets its special functions.
For example, the inherent instability of cosmetic raw materials is close to that of food. Therefore, cosmetic packaging needs to provide more effective barrier properties while maintaining cosmetic properties. On the one hand, it is necessary to completely isolate light and air, avoid product oxidation, and prevent bacteria and other microorganisms from entering the product. quality.
In addition, cosmetic packaging has high biosafety requirements, because in the additives of cosmetic packaging, some harmful substances may be dissolved by cosmetics, thereby causing cosmetics to be contaminated.
Application of PLA in the field of cosmetic packaging
PLA material has good processability and biocompatibility, and is currently the main cosmetic biodegradable packaging material. PLA material has good rigidity and mechanical resistance, and is a good material for rigid cosmetic packaging, but the high brittleness of PLA products may affect its practical application, so some scholars have mixed PLA with other polyesters, such as polyadipic acid. The blending of butylene glycol esters with butylene terephthalate (PBAT) was found to significantly reduce the brittleness of the product and increase the elasticity of the packaging. After blending PLA with polycarbonate (PC), it was found that the elastic modulus could be further improved by adding cellulose to the blend.
The use of plasticizers is also a strategy to improve the ductility and toughness of PLA material packaging, especially in flexible packaging formulations. Plasticizers can lower the glass transition temperature of PLA, resulting in lower yield stress and higher room temperature elongation at break to improve the flexibility of the membrane material. It has been reported that acetyl tributyl citrate, triacetic acid and oligoethers, oligolactates and oligoadipates are efficient plasticizers that can be used in PLA materials.
Since cosmetics are usually liquid or paste, the barrier properties of PLA material packaging are high, and inorganic additives can be used to improve the barrier properties of packaging materials. Studies have shown that a small amount of layered silicate can significantly improve the overall barrier properties of PLA packaging. Jorda. Beneyto et al. used 2 kinds of organically modified clays to produce hydrophobically modified montmorillonite, which resulted in better compatibility between biopolymers and nanoclay materials.
The improvement of PLA materials by nanotechnology is also one of the current research hotspots. Adding nano-CaCO3, nano-BaSO4 and nano-TiO2 to PLA materials can improve the mechanical properties of polymer materials, and can also act as nucleating agents to improve the crystallization of polymers.
Although nanomaterials cannot meet the requirements for food packaging, these nanocomposites have passed the European FP7BioBeauty project and can be used in cosmetic testing. In this project, taking PLA nanoclay composites as the research object, the dermatological toxicity of substances that may migrate from the composites into cosmetics was identified, and the potential use of these composites for cosmetic packaging applications was evaluated. harm. The study shows that the nanocomposite can be safely used in cosmetic packaging and meets relevant regulatory requirements.
In addition, the solvent used in cosmetics is often oil or water. The durability of PLA cosmetic packaging under water and oil conditions may be affected by its hydrolysis tendency. Therefore, the hydrolysis kinetics of PLA materials is also another research hotspot. Zhang et al. compared the hydrolytic degradation behavior of nonionic nanocrystalline cellulose (NCC) PLA nanocomposites and polyethylene glycol (PEG) PLA nanocomposites. The results show that the presence of hydrophilic PEG significantly accelerates the hydrolytic degradation of PLA, which is related to the rapid dissolution of PEG in the material, which leads to the easy entry of water molecules into the composite material and triggers the rapid hydrolytic chain scission of PLA. The thermal stability of NCC is poor, and the thermal degradation temperature of the nanocomposites decreases slightly compared with pure PLA.
