What Is Foam?

Since polyolefin is lipophilic resin, it is a low-hygroscopicity material. The cells in SOFTLON™ are not connected, which does not allow entry of water, exhibiting excellent water resistance. In the long history of SOFTLON™, this feature has extended its applications from bathroom mats to packing materials.

Crosslinking the molecular structure with entangled string-like polymers further tightens the molecular bonds, which results in a molecular lattice mesh structure, improving heat resistance and strength. With these structural features, SOFTLON™ is highly regarded for its sturdiness and flexibility compared to non-crosslinked polyolefin foam.

The cell of electron-crosslinked sheets will contain more air in the later foaming process. Cells with various expansion times create a closed cell structure in which all cell are separated with walls.

Different with a open cell structure, a closed cell structure has unique cushioning and shock absorption characterized with reasonable bouncing with no bottoming out (touching the base when pressed down).

Having excellent shock absorption even with small thickness, SOFTLON™ sheets are used package cushioning for precision instruments.

The rate represents how much the foam changes in size at each temperature when heated without an external force applied. While polyethylene foam deforms as shown in the figure on the right when heated to 80°C or higher, polypropylene foam has excellent heat resistance with a shrinkage rate of 3% or less even at 140°C.

Containing a large amount of air with high expansion times, SOFTLON™ has superior thermal insulation (= lower thermal conductivity) compared to general insulations. Each small cells in foam is closed so that the amount of convection is limited, conducting little heat, which is thought be the reason for excellent thermal insulation. Different from glass wool and rigid foam, SOFTLON™ is easy to forming and good installation. Therefore, it is suitable for insulators for filling very small spaces in houses and various machinery.

An ordinary foam increases its volume by foaming. However, the thin foam proposed by Sekisui minimizes the cell size of the bubbles during foaming to reduce the thickness of the products to the utmost limit, thus contributing to the downsizing of electronic devices.

Shock energy is generated when an object moves and physically contact with another object. The shock can be absorbed by converting it into heat energy.

The sealing property of a sealer such as tape is greatly affected, not only by the properties of the material substance, but also by its close physical contact with the uneven surface of the adherend. A material with high flexibility eliminates gaps with the adherend and realizes high sealing performance.

Polypropylene (PP) has a higher melting point than polyethylene (PE).
Therefore, with its excellent heat resistance even at high temperatures during molding, PP can achieve both excellent thermoformability and cushioning. Specifically, PP is widely used for automotive interior trim materials and fruit protection trays.

Electron beam crosslinking is a crosslinking process that accelerates electrons with a high voltage and emits them onto sheets. Since the beam electrons evenly and stably penetrates through each sheet, the resulted crosslinking is more uniform compared to other methods including that using a crosslinking agent such as peroxide (chemical crosslinking). Uniform crosslinking enables even foaming, which creates a smooth surface layer suitable for adhesion and coating.

Closed cell structure, in which air with low dielectric strength is enclosed in separated small spaces, exhibits superior dielectric strength. In addition, polyolefin, which has a relatively low permittivity compared to other general-purpose plastics, formed in a structure containing air provides even lower permittivity. With attention focused on these features, SOFTLON™ has been used to pack precision instruments and fragile modules such as RFID tags. With attention focused on these features, SOFTLON™ has been used to pack precision instruments and fragile modules such as RFID tags.

SOFTLON™, mainly composed of polyethylene, inherits the high chemical resistance of the main component. With superior resistance against acids, alkalines, and organic solvents, which have adverse effects on other foaming materials including swelling, shrinking, and to dissolving, SOFTLON™ is serving various industries from the background.

Polyolefin is a type of plastic. It is the generic name of a polymer (resin) obtained by synthesizing monomers (i.e. unit molecule) with a carbon-carbon double bond.
SOFTLON™ is foam mainly composed of polyolefin (principally polyethylene). Since it does not contain halogens such as fluorine and chlorine, it does not generate highly toxic gases when burnt.

Using thermoplastic polyolefin resin, SOFTLON™ can change the fluidity of the polymer by changing the temperature. By heating and melting, it can attach other materials or deform the foam. By taking advantage of the shape stability at room temperature, it can also be cut into complicated shapes.