Application of foaming agents in plastic products

Foaming agent is a key additive for lightweight modification of plastics, which generates uniform bubbles in the plastic matrix, forms a porous structure, reduces product density (can be reduced to 0.01-0.9g/cm ³), and endows insulation, sound insulation, buffering and other functions, suitable for almost all plastic categories such as PE, PP, PVC, PS, PU, etc. According to the foaming mechanism, it can be divided into physical foaming agents (such as CO ₂, nitrogen, alkanes) and chemical foaming agents (such as azodicarbonamide AC, sodium bicarbonate). The former is environmentally friendly and efficient, while the latter has low cost and uniform bubbles. It is widely used in packaging, building materials, automobiles and other fields, and is the core support for achieving weight reduction, consumption reduction and functional upgrading of plastic products.

1、 The core mechanism of foaming agent: dual value of pore forming and empowerment

1. Physical foaming: pore formation through phase transition or dissolution precipitation

Physical foaming agents do not undergo chemical reactions and achieve pore formation through pressure changes and temperature increases

Inert gases (CO ₂, nitrogen): Dissolve in plastic melt under high pressure, quickly precipitate and form bubbles after pressure reduction, with fine and uniform bubbles, no pollution, suitable for polyolefin plastics such as PE and PP;

Low boiling point liquids (n-pentane, Freon substitutes): gases are generated by vaporization during heating, which are commonly used in PU rigid foam, PS foam plastics, such as refrigerator insulation, expanded polystyrene (EPS) lunch boxes.

2. Chemical foaming: relies on decomposition to produce gas and form pores

Chemical foaming agents decompose at plastic processing temperatures, releasing gases such as N ₂ and CO ₂ to form bubbles, which are divided into organic and inorganic categories:

Organic foaming agent: Azodicarbonamide (AC) is the most commonly used variety, with a decomposition temperature of 160-200 ℃, high gas production (200-300mL/g), uniform bubbles, and suitable for PVC, PE, PP foaming products;

Inorganic foaming agent: Sodium bicarbonate (baking soda) has an extremely low cost, decomposes and releases CO ₂, and has coarse bubbles. It is commonly used for low-end PE foam boards and PVC foam slippers.

2、 Mainstream foaming agent types and compatible plastics: precise scene matching

The type of foaming agent represents the core advantages of the product and is suitable for typical plastic applications

Physical foaming agent - inert gas CO ₂, nitrogen, environmentally friendly and non-toxic, fine bubbles, no residual PE, PP, PET PE foaming buffer packaging, PP foaming car door panels, PET foaming lunch boxes

Physical foaming agent - low boiling point liquid n-pentane, high foaming efficiency, moderate cost PU, PS PU hard foam insulation layer, EPS foam board

Organic chemical foaming agent azodicarbonamide (AC) has high gas production, uniform bubbles, and good stability for PVC, PE, PP PVC foam flooring, PE foam pipes, PP foam toys

Inorganic chemical foaming agent sodium bicarbonate has extremely low cost, safe and odorless PE, PVC low-end PE foam pad, PVC foam slippers

3、 Application Practice of Key Plastic Foam Products

1. Packaging field: the main force of cushioning protection

EPS foam box: low boiling liquid foaming agent, light in weight and strong in buffering, can effectively protect fresh and fragile products, with a density of only 0.02-0.05g/cm ³;

PE foam buffer film: using CO ₂ physical foaming, no residual pollution, used for electronic products and home appliance packaging, with both shock absorption and moisture resistance functions.

2. Building materials field: dual function of insulation and sound insulation

PU hard foam insulation board: n-pentane foam, high closed cell rate, low thermal conductivity of 0.022W/(m · K), widely used for building exterior wall insulation, refrigerator freezer interlayer;

PVC foam flooring: AC foam agent foam reduces density by 30% -50%, with anti slip and sound insulation effects, suitable for home and shopping mall floor decoration.

3. Automotive field: Lightweight to reduce fuel consumption

PP foam car door panel: nitrogen physical foaming, reducing weight by 20% -30%, while improving sound insulation and noise reduction performance, helping cars save energy and reduce emissions;

PE foam seat filler: Sodium bicarbonate foam, low cost, good elasticity, enhances seat comfort and cushioning.

4、 Development trend: environmental protection, refinement, and multifunctionality

Environmental substitution: Eliminate fluorinated foaming agents, promote green physical foaming agents such as CO ₂ and nitrogen, and comply with EU REACH and Chinese environmental standards;

Micro porous foaming: Developing nano scale bubble foaming technology with bubble diameters less than 10 μ m to enhance the mechanical properties of products, such as PP micro porous foaming material, which can be used for automotive structural components;

Multi functional integration: Developing "foaming+flame retardant+antioxidant" composite additives, simplifying formulas, and adapting to high-end scenarios, such as using flame retardant PU foam insulation materials for building fire prevention.

5、 Summary

Foaming agents have achieved a transformation from "solid and heavy" to "lightweight and multifunctional" by endowing plastics with a porous structure, playing an irreplaceable role in packaging weight reduction, building material insulation, automotive lightweighting, and other fields. In the future, with the breakthrough of environmentally friendly foaming technology, foamed plastics will further expand their application boundaries and help the plastic industry develop towards a green and efficient direction.