How to ensure the quality of the product when using PP materials with recycled materials?

To ensure the quality of products using PP (polypropylene) materials with added recycled materials, strict control can be carried out from aspects such as recycled material processing, formula design, production process control, and quality inspection. The following is a detailed introduction:
Recycled material processing
Strictly screen the recycling source: choose recycled materials with reliable and relatively single sources, such as scraps recycled from a specific factory. This type of recycled material has fewer impurities and relatively stable performance. Avoid using recycled materials with complex sources and possible serious contamination, such as recycled materials mixed from different types of plastic products, whose composition and performance are difficult to control.
Thorough cleaning and sorting: Recycled materials need to be thoroughly cleaned before use to remove impurities such as dirt, grease, and dust on the surface. At the same time, use manual sorting or automated sorting equipment to separate PP recycled materials of different colors, qualities, and types to ensure the consistency of recycled material quality.
Deep processing of recycled materials: Use physical or chemical methods to modify recycled materials to improve their performance. For example, by adding additives such as compatibilizers and stabilizers, the compatibility and stability of recycled materials and new materials can be improved; using a screw extruder to granulate the recycled materials, further remove impurities and make the performance of the recycled materials more uniform.
Formula design
Reasonably determine the addition ratio: According to the performance requirements and actual use of the product, reasonably determine the addition ratio of recycled materials. For products with high performance requirements, such as food packaging, medical devices, etc., the addition ratio of recycled materials should be relatively low; while for some products with less stringent performance requirements, such as ordinary daily necessities, industrial accessories, etc., the addition ratio of recycled materials can be appropriately increased. Generally speaking, the addition ratio of 30% - 50% is more common, but the optimal ratio needs to be determined through experiments.
Add appropriate additives: In order to make up for the shortcomings in the performance of recycled materials, appropriate additives need to be added. For example, adding antioxidants can improve the antioxidant properties of the product and extend its service life; adding toughening agents can improve the toughness of the product and prevent the product from brittle cracking during use; adding lubricants can improve the processing fluidity of the product and make the product easier to form.
Production process control
Optimize processing parameters: Since the performance of recycled materials is different from that of new materials, it is necessary to optimize the processing parameters. For example, appropriately increasing the processing temperature can improve the fluidity of recycled materials, but be careful to avoid excessive temperature causing material degradation; adjust the injection pressure and speed to ensure that the product is well molded and avoid defects such as bubbles and lack of material.
Strengthen equipment maintenance: Ensure that the production equipment is in good operating condition and regularly clean, maintain and repair the equipment. For example, regularly clean the screw, barrel and other components to prevent residual recycled materials from accumulating in the equipment and affecting product quality; check the heating system, cooling system and transmission system of the equipment to ensure their normal operation.
Standardize the operating process: formulate strict production operating procedures and require operators to strictly follow the procedures. For example, during the feeding process, pay attention to controlling the feeding speed and feeding amount to avoid uneven feeding; during the molding process, pay attention to observing the molding of the product and adjust the process parameters in time.
Quality inspection
Establish a complete inspection system: Establish a full-process quality inspection system from raw materials to finished products, and strictly control the quality of each link. For example, conduct quality inspection on recycled materials, including physical and chemical properties; conduct random inspections on semi-finished products in the production process to promptly identify problems and make adjustments; conduct comprehensive inspections on finished products to ensure that the products meet relevant standards and requirements.
Use a variety of testing methods: Use a variety of testing methods to test product quality, such as appearance inspection, dimensional measurement, physical property testing, chemical analysis, etc. Appearance inspection can detect whether there are defects such as flaws, scratches, bubbles, etc. on the surface of the product; dimensional measurement can ensure that the size of the product meets the design requirements; physical property testing can detect the strength, toughness, hardness and other performance indicators of the product; chemical analysis can detect whether the product contains harmful substances.
Regularly calibrate testing equipment: Regularly calibrate and maintain testing equipment to ensure the accuracy and reliability of test results. For example, regularly calibrate equipment such as tensile testing machines and hardness testers to ensure their measurement accuracy; clean and maintain testing equipment to prevent equipment failures from affecting test results.