The characteristics of rigid and soft core foam:
1. Rigid foamed plastic means that at room temperature, the polymer constituting the foamed plastic is in a crystalline or amorphous state, and their glass transition temperature is higher than normal temperature. Therefore, the foamed plastic has a harder texture at normal temperature.
2. The melting point of the soft foamed plastic, that is, the polymer constituting the foamed plastic is lower than normal temperature or the glass transition temperature of the amorphous polymer is lower than normal temperature, and the material is soft at normal temperature.
3. Semi-rigid (or semi-soft) foam is a foam between the above two types.
Flexible foam can also be divided into low foaming and high foaming categories. Generally, the expansion ratio (the multiple of the volume increase after foaming than before the expansion) is less than 5 is called low expansion, and the expansion is greater than 5 is called high expansion. Foam plastic is a type of polymer material formed by a large number of gas micropores dispersed in solid plastic. It has the characteristics of light weight, heat insulation, sound absorption, shock absorption, etc., and its dielectric properties are better than matrix resins, and it has a wide range of uses. Almost all kinds of plastics can be made into foam plastics, and foam molding has become an important field in plastic processing.
Foam plastic is also called porous plastic. A plastic with numerous micropores inside, made from resin as the main raw material. Lightweight, heat-insulating, sound-absorbing, shock-proof and corrosion-resistant. There are soft and hard points. It is widely used as heat insulation, sound insulation, packaging materials and car and ship shells. Compared with pure plastic, foam plastic has low density, light weight and high specific strength. Its strength increases with the increase of density. It has the ability to absorb impact load, excellent cushioning and shock absorption performance, sound insulation and sound absorption performance, and thermal conductivity.
Low, good thermal insulation performance, excellent electrical insulation performance, corrosion resistance and mildew resistance. The soft core material foam has excellent elasticity and other properties. Plastic with many tiny pores inside. It is made by mechanical method (inject air or carbon dioxide to make foam while performing mechanical stirring) or chemical method (add foaming agent). There are two types: closed cell type and open cell type. The pores in the closed-cell type are isolated from each other and have floatability; the pores in the open-cell type are interconnected and have no floatability. It can be made of polystyrene, polyvinyl chloride, polyurethane and other resins. It can be used as heat insulation and sound insulation material and has a wide range of uses.
(1) The bulk density is very low, which can reduce packaging weight and reduce transportation costs;
(2) It has excellent shock and vibration energy absorption, which can greatly reduce product damage when used for cushioning and shockproof packaging;
(3) 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 acids and alkalis;
(5) Low thermal conductivity, which can be used for thermal insulation packaging, such as ice cream cups, fast food containers and thermal fish boxes, etc.;
(6) The molding process is convenient, and various foam pads, 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 sheet can be made into various fast food containers after thermoforming. In addition, foam blocks can also be bonded with adhesives or other materials to make various cushioning pads.