Plastic Injection Molding Products in Daily Life

 

1. PET or PETE: Polyethylene Terephthalate

PET is predominantly used to manufacture high-transparency consumer packaging, such as carbonated beverage bottles, water bottles, juice containers, and optical protective films.

• Engineering Advantages: Offers exceptional clarity, allowing consumers to inspect contents, alongside robust carbon dioxide barrier properties (acid resistance for carbonated drinks) and high water-proof sealing capability.
• Thermal Limitations & Safety Note: PET exhibits a relatively low heat deflection temperature and should not be exposed to liquids exceeding 70°C, which triggers structural deformation. For long-term food contact stability, PET beverage bottles must adhere to rigid national food-grade standards to prevent the migration of residual trace monomers or oligomers (such as diethylene glycol). It is strictly designed for single-use applications.

2. HDPE: High-Density Polyethylene

HDPE is a versatile, translucent, or opaque polymer characterized by its rigid, high-molecular-weight tactile feel. It is widely specified for chemical containers, heavy-duty shopping bags, waste bins, and household product housings.

• Engineering Advantages: Demonstrates superior resistance to aggressive chemical solutions, making it the ideal material for chemical injection molding products, industrial cleaning supply bottles, and cosmetic bath product packaging.
• Thermal & Operational Limits: HDPE safely withstands continuous thermal loads up to 110°C, making it compliant for temporary hot-food contact. However, because industrial cleaning and bath container residues are notoriously difficult to sanitize completely, recycling these post-consumer containers back into food or pharmaceutical-grade packaging is not recommended.

3. PVC: Polyvinyl Chloride

PVC is historically favored by custom plastic manufacturers for industrial profiles, durable floor mats, raincoats, protective wire/cable sheaths, water pipelines, electrical switches, and wall sockets.

• Engineering Advantages: Features excellent mechanical strength, flame retardancy (self-extinguishing properties), supreme weatherability, and exceptional resistance to acidic corrosive environments.
• Thermal & Safety Note: PVC degrades and softens at approximately 81°C. Due to the historical use of heavy-metal heat stabilizers and phthalate plasticizers (such as DOP) to improve flexibility, PVC carries a risk of toxic leaching under high temperatures or when in contact with oils. Consequently, in modern food-contact and medical device applications, PVC has been aggressively replaced by safer alternatives like PP and PE.

4. LDPE: Low-Density Polyethylene

LDPE is highly flexible and primarily processed via extrusion blow molding and film blowing. It is extensively utilized for stretch wraps, agricultural films, squeeze tubes (e.g., toothpaste or cosmetic hoses), and as a waterproof inner lining for paper milk and beverage cartons.

• Engineering Advantages: Outstanding ductility, elongation, and impact strength at low temperatures.
• Thermal Note: LDPE loses its structural integrity at temperatures approaching 100°C. Plastic cling wraps made of LDPE will begin to melt at approximately 110°C; therefore, consumers must remove LDPE wraps before reheating food in high-temperature microwave environments.

5. PP: Polypropylene

PP is one of the most widely used materials in food-grade plastic molding and engineering applications. Typical products include microwave-safe meal boxes, airtight crisper containers (e.g., Lock & Lock boxes), medical syringes, automotive bumpers, consumer basins, buckets, and hangers. It is also spun into fibers for non-woven fabrics and industrial ropes.

• Engineering Advantages: It is the lowest-density commodity plastic container material, featuring high surface gloss, exceptional chemical resistance, and a high melting point, allowing it to withstand temperatures up to 130°C to 167°C. It is the only plastic universally certified for microwave heating.
• Manufacturing Check: When producing microwave-safe containers, engineers must note that while the container body is made of high-heat PP, the transparent lid is frequently molded from PS (Polystyrene). Molders and consumers must ensure the lid is removed prior to high-temperature microwave cycling to prevent melting.

6. PS: Polystyrene

PS is utilized in both rigid and foamed states. Common applications include CD jewel cases, disposable rigid cups, fast-food clamshell containers, ice cream tubs, and structural insulation sheets.

• Engineering Advantages: Provides magnificent optical clarity, high rigidity, and excellent low-temperature impact resistance, making it a favorite for frozen dessert packaging.
• Thermal Limitations: While structurally rigid, standard PS has low thermal threshold stability under boiling conditions. It is best restricted to cold-storage applications or dry, ambient food containment.

7. Other (PC, Acrylic, Nylon, Bioplastics, etc.)

The “Number 7” category is a catch-all designation for engineering resins that do not fall into codes 1-6. This includes Polycarbonate (PC) used in bulletproof glazing and electronics, Polyamide (Nylon) for high-wear gears, and advanced co-polymers.

Leverage Professional Material Expertise at CNMOULDING

Selecting the correct resin identification code is only the first step in a successful product lifecycle. At CNMOULDING, we specialize in transforming raw resins—from flexible LDPE to high-temperature Polypropylene—into high-precision, defect-free components. Our state-of-the-art injection tooling capabilities ensure optimal shrinkage compensation and uniform material flow, regardless of your chosen resin density.

Contact our Shanghai engineering base today to optimize your product’s injection mold design and material specification for global regulatory compliance.