The discoloration of plastic-colored products can result from various factors, including the lightfastness of pigments, dyes, and the resistance to oxidation, heat, acids, and alkalis, along with the characteristics of the resin employed. Before producing masterbatches, it's essential to evaluate these properties comprehensively, especially considering the processing conditions and intended use of the plastic product.
1. The lightfastness of colorants significantly impacts how quickly products fade. For items exposed to strong sunlight outdoors, the lightfastness rating of the chosen colorants is crucial. A lower rating—four or five grades for indoor products or six for outdoor ones—is insufficient. Ideally, the lightfastness should reach seven or eight grades for outdoor applications. This ensures durability under prolonged UV exposure. Adding UV stabilizers like absorbers to the masterbatch can enhance the light resistance of both the colorants and the final plastic product.
2. The thermal stability of heat-resistant pigments determines how well they withstand heat without fading or degrading. Inorganic pigments, made from metal oxides and salts, offer excellent thermal stability and can endure high temperatures. However, organic pigments may undergo structural changes or slight decomposition at certain temperatures. For plastics like PP, PA, and PET, where processing temperatures exceed 280°C, it’s vital to select pigments with adequate heat resistance. The pigment's heat resistance time should ideally last between 4 to 10 minutes. Certain metal ions in pigments can accelerate resin degradation; those containing copper, manganese, iron, and cobalt notably promote the aging of polyolefins, whereas potassium, sodium, cadmium, and calcium-based pigments have less impact. Pure metals, metal oxides, and metal salts exhibit increasing effects in that order.
3. Oxidation resistance plays a role in the degradation of some organic pigments, particularly during high-temperature processing or when exposed to strong oxidizing agents like chromate in chrome yellow. Mixing certain pigments, such as lakes, azo pigments, and chrome yellow, can lead to a gradual reduction in their red tones due to oxidation.
4. The fading of acid and alkali resistant colored plastic products relates to the chemical resistance of the colorants. For instance, molybdenum chrome red resists dilute acids but is sensitive to alkalis, while cadmium yellow lacks acid resistance. Both pigments interact strongly with phenolic resins, reducing the heat resistance, weather resistance, and fading durability of colorants.
In conclusion, understanding and addressing these factors is critical for ensuring the longevity and quality of plastic-colored products. Balancing these properties requires careful consideration of each component's role and potential interactions.
Black Transparent Thigh High Socks,Black Thigh High Lace Stockings,Lace Thigh High Stockings,Transparent Lace Stockings
Lianyungang Continuation Qianyuan International Trade Co., Ltd. , https://www.zxunderwear.com