China Guangzhou Donoyo Chemical Co., Ltd Company News

  Injection molding PC/ABS blends can present specific challenges. Silver streaks or silver marks, appearing as silver-white lines along the flow direction, are primarily caused by trapped gases—often from moisture in the material, entrapped air, or pyrolysis gases from overheating. Solutions begin with thorough material drying, followed by process adjustments and ensuring adequate mold venting. Flow marks, surface patterns from a cooling melt front, are addressed by increasing melt temperature to improve fluidity, alongside adjustments to mold temperature and injection speed. Shrinkage and voids (sinks or dents) result from insufficient packing or cooling issues. Corrective measures include raising mold and melt temperatures, increasing holding pressure and time, and optimizing gate design. Warpage and deformation stem from internal stress or uneven cooling/shrinkage, remedied by process adjustments like longer cycles and lower melt temps, as well as design modifications such as adding ribs and uniform wall thickness. Jetting, caused by a fast-moving melt stream "shooting" into the cavity, is solved by increasing melt/nozzle temperature, reducing injection speed, raising mold temperature, or modifying gate design. Pitting or surface defects from poor additive dispersion require checking material batches, ensuring proper drying, and potentially adding a dispersant or back pressure. Delamination or peeling is often related to high shear stress causing flow separation, potentially exacerbated by compatibility issues between PC and ABS. Solutions involve verifying material formulation (compatibilizer use), increasing melt and mold temperatures to reduce shear, and avoiding restrictive gates or high-friction mold surfaces.

  Plastic alloys are high-performance, functional, or specialized materials created through the physical blending or chemical grafting of different polymers. These compounds enhance or modify the properties of base resins and can reduce costs, making them indispensable in automotive, electronics, precision instruments, and construction. They represent one of the most dynamic and rapidly growing sectors within the plastics industry. While general-purpose alloys based on PVC, PE, PP, and PS remain widely used, the focus in advanced markets has shifted towards higher-value engineering plastic alloys. These typically involve blends where key engineering resins like PC (Polycarbonate), PBT, PA (Nylon), POM (Acetal), PPO/PPE, and PTFE form the primary matrix, including modifications of ABS. Accelerating the development and application of these sophisticated materials is crucial for maintaining competitiveness in the global plastics sector.

  Processing PBT requires precise control. The melt temperature range is narrow, typically between 250-260°C; temperatures below 240°C can lead to freezing, while exceeding 270°C risks thermal degradation. A barrel temperature profile maintaining around 210°C is recommended, with a mold temperature of 60-80°C. Injection pressure should be set between 100-140 MPa, with holding pressure at 50-60% of the injection pressure. A back pressure of 5-10 MPa helps avoid excessive frictional heat. High injection speed is crucial due to PBT's rapid solidification and crystallization rates, preventing premature cooling in the flow path. Adequate mold venting is essential to avoid air traps and potential burning. Screw speed should correspond to a maximum linear speed of 0.5 m/s. The dosing stroke is recommended at (0.5-3.5)D, and the total residence time in the barrel should not exceed 5 minutes to prevent thermal degradation. Material must be pre-dried at 120°C for 4 hours. For regrind usage, flame-retardant grades allow up to 10% recycled content if properly dried, while non-FR grades can incorporate up to 20%. Shrinkage largely depends on mold temperature, ranging from 1.4%-2.0% for unfilled PBT. Adding 30% glass fiber reduces shrinkage to 0.4%-0.6%. Gate design should favor direct or pinpoint gates for glass-filled grades, ensuring balanced filling. Hot runner systems require closed-loop temperature control. Standard screws with non-return valves and open nozzles are suitable. For machine downtime, the heater should be switched off and the barrel purged.

  Selecting materials for charging gun connectors involves evaluating several options, including PET, PBT, and PA (nylon). While PA (polyamide) reinforced with glass fiber and flame retardant (PA+GF+FR) is often a primary choice for many customers, PBT+FR becomes a preferred alternative when dimensional stability and minimal shrinkage are critical. PET also serves as a viable material selection option. Charging gun materials must pass rigorous tests for mechanical performance, temperature resistance, flame retardancy (FR), and electrical properties. PBT (Polybutylene Terephthalate), a thermoplastic polyester, is particularly well-suited for plugs and sockets due to its excellent mechanical strength, high electrical insulation, good thermal properties, strong weather resistance, and cost-effectiveness. For the connection base, the primary material selection schemes are PA+GF+FR or PBT+FR. When enhanced strength and rigidity are needed, a composite like PBT with 15-30% glass fiber and flame retardant (PBT+GF+FR) is considered.

  Recycled rubber and recycled plastic differ fundamentally in material behavior, sourcing, and processing. Plastics undergo permanent plastic deformation, whereas rubber exhibits elastic deformation—able to stretch and return to its original shape. At room temperature, plastic is typically a hard solid, while rubber remains soft, flexible, and stretchable. Waste rubber cannot be reused directly and must be processed into reclaimed rubber through crushing, devulcanization (regeneration), and refining. The regeneration process breaks partial molecular chains and cross-links in vulcanized rubber using softeners, activators, heat, oxygen, and mechanical shear. In contrast, recycled plastics are reprocessed via physical or chemical methods such as pretreatment, melt granulation, and modification. While both support circular economy goals, they differ significantly in performance characteristics, raw material sources, and production technologies.

  Polycarbonate is an amorphous engineering plastic commonly sourced from textile accessories, automotive lights, signal lenses, candy molds, CDs, telecom and photographic equipment, as well as plastic abrasive scraps. The recycling process includes: Selection and sorting of purchased PC waste, often requiring separation by color. Some items like textile parts are modified, while CDs and lamp covers may have coatings. Cleaning and deplating of colored PC, CDs, and lamp holders using processes similar to those for ABS. The materials are then dried, classified, and fed into an extruder. Color adjustment: yellowish PC can be processed into porcelain white, transparent PC can remain transparent, and other colors are achieved using colorants and additives. Specialized extruders are used for pelletization. However, PC is prone to aging and cannot withstand multiple recycling cycles, so granulation must be done carefully before cutting and packaging. Recently, Zhejiang Cixi has intensified regulation of the PC recycled material market to curb environmental pollution. Many small enterprises lacking production licenses or operating in poor conditions have been shut down. This has drawn significant attention from manufacturers of PC-based products such as solar panels and endurance boards.

  Recycled plastic modification involves enhancing the properties of recycled plastics through physical or chemical methods, aiming to achieve performance levels close to, equal to, or surpassing those of virgin plastics. This process enables wider reuse in various plastic products. For example, wood-plastic composite—a eco-friendly modified material—is produced by blending waste wood with recycled plastic along with compatibilizers and processing aids. Such materials are now widely used in municipal projects like urban landscaping and flooring. Due to the heterogeneity and often inferior properties of recycled plastics, modification techniques may include blending with reinforcing agents (e.g., glass fibers), adding toughening elastomers, or using compatibilizers and chain extenders to im-prove interfacial adhesion and molecular weight. These enhancements boost strength, durability, and compatibility. Ultimately, plastic modification supports waste recycling, reduces plastic pollution, and contributes to environmental protection.

The Global Recycled Standard (GRS) is an international voluntary product certification that verifies the recycled material content in products, assesses the environmental impact of production, and ensures adherence to specific social and chemical standards. Developed by Textile Exchange, GRS tracks the use and flow of recycled materials across the supply chain, promoting transparency and sustainability. A Transaction Certificate (TC) is an official document issued by a certification body to confirm that a specific batch of goods complies with GRS requirements. It serves as proof that the products—from raw materials to final output—follow the standard’s guidelines and are part of a monitored production and sales system. Purpose and Role of GRS Certification GRS certification aims to increase the use of recycled materials, reduce resource waste, and advance the circular economy. It enables companies to demonstrate transparency in recycled content sourcing while meeting environmental and social responsibility criteria. The standard covers recycled content thresholds, supply chain traceability, social and environmental practices, and chemical restrictions. Application Process and Requirements for GRS Certification To obtain GRS certification, a company must first submit documentation to an accredited certification body for review. Once certified, the company can apply for a TC certificate by providing order contracts and relevant details. The certification body then issues the TC, validating that the shipped goods meet GRS standards.

  The Post-Consumer Recycled (PCR) material recycling process is a systematic workflow designed to transform used plastic items into reusable raw materials. It involves several critical stages to ensure quality and sustainability. Collection & Sorting begins with gathering post-consumer plastics such as packaging and bottles, which are then categorized by polymer type and thoroughly cleaned to remove non-plastic contaminants. Next, Shredding mechanically crushes the cleaned materials into smaller fragments to facilitate efficient further processing. During Melting & Purification, shredded plastics are heated under controlled temperatures until molten, while impurities are filtered out to enhance material purity. The Pelletization stage then extrudes the purified molten plastic into uniform pellets, ready for reuse in manufacturing. Certification Requirements ensure compliance with international sustainability standards like the Global Recycled Standard (GRS). To achieve certification, the final product must contain a minimum threshold of PCR content (e.g., 20%). The process includes traceability audits and verification of the entire recycling chain’s integrity, guaranteeing transparency and environmental accountability.

  Plastic pollution manifests in several damaging forms. Visual Pollution occurs when discarded plastics litter urban and natural environments, creating an eyesore and degrading the aesthetic value of public spaces. Marine Pollution is a critical issue, with millions of tons of plastic waste entering oceans annually, entangling, suffocating, and being ingested by marine animals, leading to devastating declines in biodiversity. Soil Pollution happens when plastic films and fragments accumulate in agricultural land, hindering water and nutrient absorption by crops and potentially leaching additives into the soil and groundwater. Perhaps the most insidious is Microplastic Pollution, where plastics break down into tiny particles that persist in the environment, contaminating water sources, entering the food chain, and posing a potential risk to human health through ingestion and inhalation.

  The use of Post-Consumer Recycled (PCR) plastic pellets is gaining significant traction in the kitchenware industry, driven by both consumer awareness and robust environmental legislation. Brands are increasingly adopting these materials as part of a broader sustainability upgrade.   Within the spectrum of eco-friendly plastics, PCR pellets stand out as a highly competitive and practical option. Compared to single-use biodegradable alternatives like Polylactic Acid (PLA), PCR plastics offer a more stable and reliable supply chain, as they are derived from the existing waste stream. Furthermore, their cost is generally more affordable and predictable, making them a viable choice for manufacturing durable kitchenware items such as utensils, storage containers, and cutting boards, without compromising on performance or economic feasibility.

  The key distinction between PCR (Post-Consumer Recycled) and PIR (Post-Industrial Recycled) plastic lies in their point of origin within the product lifecycle. PCR material comes from products that have been used by consumers and then discarded, such as recycled water bottles, food containers, or old electronics housings. The recycling process for PCR is complex, involving collection, sorting, intensive washing, and reprocessing to ensure purity and performance.   In contrast, PIR plastic, also known as post-industrial regrind, is generated during the manufacturing process itself. It includes scrap like sprues, runners, off-spec parts, and trimmings that never reached the consumer. Because this material is clean, controlled, and of a known composition, its recycling is much more straightforward. It can often be reground and immediately reintroduced into the production line with minimal processing, making it a highly efficient form of internal recycling.