Rigid foam plastics is a kind of foam plastic, which refers to foam plastic with elastic modulus greater than 700MPa. Rigid foam plastic refers to no flexibility, high compression hardness, deformation can be generated when the stress reaches a certain value, and it cannot be restored to its original state after the stress is relieved. of foam plastic. ISO also stipulates that the foam whose thickness is reduced by more than 10% after compressing it to 50% and then releasing the pressure is rigid foam. It is often used in related aspects by its thermal insulation and mechanical properties. Representative products are polystyrene foam, rigid polyurethane foam, and foams such as phenolic, amino, epoxy, thermosetting acrylate resins, and rigid polyvinyl chloride foam. It can be used as thermal insulation material, interlayer material, packaging material, sound insulation and shockproof material, building material, etc.
(1) The bulk density is very low, which can reduce the packaging weight and reduce the transportation cost;
(2) It has excellent absorption of shock and vibration energy, which can greatly reduce the damage of products when used for buffering and shock-proof packaging;
(3) It has strong adaptability to changes in temperature and humidity, and can meet the requirements of general packaging conditions;
(4) Low water absorption, low hygroscopicity, good chemical stability, will not corrode the contents, and have strong resistance to chemicals such as acid and alkali;
(5) Low thermal conductivity, can be used for thermal insulation packaging, such as ice cream cups, fast food containers and thermal insulation fish boxes;
(6) The molding process is convenient, and various foam pads, EPS foam blocks, sheets, etc. can be made by molding methods such as molding, extrusion, and injection. It is easy to carry out secondary molding processing, such as foam sheets can be made into various fast food containers by thermoforming. In addition, the foam block can also be bonded by itself or with other materials with adhesives to make various cushioning pads and the like.
There are many classification methods of foam plastics, and there are three common ones.
Classified by hardness
It is divided into three categories: flexible foam, rigid foam and semi-rigid foam.
Flexible foam plastic with elastic modulus less than 70MPa
Rigid foam plastic with elastic modulus greater than 700MPa
Semi-rigid foam plastic elastic modulus 70~700MPa
Sort by density
It is divided into three categories: low foaming, medium foaming and high foaming foam.
Low foaming foam with a density greater than 400kg/m3
Medium foaming foam density 100~400kg/m3
High-foaming foam with a density of less than 100kg/m3
Classification by cell structure
The interconnected micro-cells are called open-cell foams, and those that are closed to each other are called closed-cell foams.