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Injection moulded food safe pp material part

PP Injection Moulding Material

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What is Polypropylene (PP)?

Injection moulded polypropylene (PP) is a thermoplastic addition polymer that is durable, robust and offers excellent chemical, electrical and fatigue resistance at high temperatures. It is the most common frequently used plastic in automotive manufacturing and is often referred to as a ‘safer’ material option.


Injection molding PP Material


Advantages of PP injection moulding


  • Very Affordable: PP is a relatively low-cost material compared to other engineering plastics. This makes it an attractive option for cost-sensitive applications and an economical choice for large-scale production.
  • Lightweight: PP has a low density, resulting in lightweight finished products. This characteristic is particularly advantageous in industries such as automotive and packaging.
  • Good Chemical Resistance to Many Substances: Polypropylene exhibits excellent resistance to a wide range of chemicals, including acids, alkalis and organic solvents.
  • Great Electrical Insulation Properties: PP is an excellent electrical insulator, making it suitable for electrical and electronic components.
  • High Resistance to Moisture Absorption and Fatigue: PP has low moisture absorption properties, which helps maintain dimensional stability and prevents degradation due to moisture.


Disadvantages of PP injection moulding

While polypropylene has many advantages, its not without its disadvantages. It’s important to evaluate these limitations against the specific requirement of the application of your part before selecting PP as a material choice.


  • Poor Bonding Qualities: Injection moulded polypropylene has low surface energy, which makes it difficult to bond, glue or paint compared to other plastics.
  • Susceptible to UV Deterioration: PP is vulnerable to ultraviolet (UV) radiation degradation. This makes it less suitable for outdoor applications unless it is properly stabilised with additives.
  • High Flammable: Pure polypropylene has limited flame resistance and can burn readily when exposed to a flame. However, flame-retardant additives can be added to improve its fire resistance properties.
  • Sensitive to Aromatics and Chlorinated Solvents: While PP exhibits good resistance to many chemicals, chemicals like chlorinated solvents and aromatic hydrocarbons can cause swelling and softening.
  • Limited Dimensional Stability: Polypropylene has moderate dimensional stability compared to some other plastics. It can experience significant shrinkage during cooling after moulding, leading to potential dimensional variations.


What is PP material used for?

Polypropylene is a versatile material with a wide range of applications across the automotive, medical and many other industries. Some typical applications of PP include:


  • Automotive exterior components like car bumpers
  • Medical products and tools
  • Food packaging
  • Plastic casing in electrical goods


Get injection moulding parts in PP material

At HLH Rapid, we offer an extensive selection of resins to cater to your specific custom injection moulding needs, including Polypropylene. To obtain a quote, simply upload your CAD file HERE and provide us with the details of your project including quantity, material and any surface finish requirements. Our dedicated team will then get back to you with a quote within a day.

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