“The Sumo Wrestler”: Tough yet cushioned
What is Foam?
Plastic foams
Foams refer to porous materials manufactured by dispersing bubbles in a plastic. Foams mean bubbles. Plastics are generally perceived as hard objects, but foams are soft and can absorb impact because they contains a lot of air inside. Foams also have excellent thermal insulation and lightweight characteristics, etc.
Familiar productsin which foams are used
Cushioning materials at home
At home, foams are used as kitchen sponges as well as cushioning materials for chairs and pillows, etc. Foams are used for various applications in our daily lives as essential components and make our daily lives comfortable.
Foams are similar to sumo wrestlers.
Foams, which represent SEKISUI CHEMICAL’s core technologies, will be plainly explained with fun in analogy to sumo wrestlers.
Why are foams similar to sumo wrestlers?Sumo wrestlers are generally perceived as being tough because they clash with each other, but they appear to be somewhat soft to hold on to. This image also applies to foams.Foams are strong but also provide cushioning performance. We will explain foams with various features in analogy to sumo wrestlers.
12 main features
Impact absorbing performance
Uniform dispersion of impact energy
The spongy and soft belly of sumo wrestlers gently catches objects. The bubble structure of foams uniformly disperses the physical pressure and absorbs impact. Compared to other materials, foams demonstrate high impact-absorbing performance. Sofa cushions are soft and comfortable to sit on due to the same principle.
Sound insulation performance
Impact absorbing performance also absorbing the sound of impact, such as rain noise
The spongy and soft body of sumo wrestlers can absorb both impact and sound. The impact absorbing performance of foams also absorbs the impact sound generated at the time of impact. Thus, foams also serve as sound insulators when applied to roofs and floors.
Water resistance
Preventing ingress of moisture
The open hand strikes of sumo wrestlers repel water. Resins whose water absorption capacity is low (polyolefin resins) are used as materials. The closed cell structure, in which bubbles are independent from each other, prevents ingress of moisture. The materials and structures demonstrate excellent water resistance. Foams are used for shower mats and packing materials.
Thermal insulation performance
Excellent thermal insulation performance because the materials contain a lot of air
A sumo wrestler in a down jacket blocks cold (hot) air. Foams demonstrate excellent thermal insulation performance because they contain a lot of air. The closed cell structure of foams maintains the thermal insulation performance because it prevents ingress of water. Foams are also easy to process and suitable as thermal insulation materials for very narrow gaps, etc. They are used in homes and various machines, etc.
High-strength durability
Strong, flexible, and tear-resistant
Sumo wrestlers build strong and flexible bodies through rigorous training. Training for foams refers to crosslinking. Crosslinking enables the internal structures to be intertwined in a more complex manner, forming a close network of molecules. This structure makes the materials strong and flexible and resistant to strong forces. * Crosslinking forms a network structure by linking molecules.
Chemical resistance / Oil resistance
Excellent resistance to chemicals and oils
The open hand strikes of sumo wrestlers also repel chemicals and oils.
Foams made mainly from polyethylene maintain the high chemical resistance of polyethylene. They are also highly resistant to acid, alkali, or organic solvents, etc., which affect foams made from other materials. Thus, they are used as essential components in various industries.
Thinness
Capable of producing foams as thin as a human hair
SEKISUI also has extremely thin sumo wrestlers. Their thickness is equivalent to a human hair (0.04 mm). The volume of ordinary foams increases by foaming. However, thin foams proposed by SEKISUI can minimize thickness by minimizing the bubble size during foaming. Such foams contribute to miniaturization of electronic devices.
Surface smoothness
Characterized by a uniform and smooth surface
Sumo wrestlers have a slick and smooth skin.
Foams have structures that consist of bubbles. Dense and uniform arrangement of bubbles (electron beam crosslinking) makes the surface of foams smooth. This surface smoothness is suitable for adhesive coating and is effective for applying adhesive bandages, etc. to the human skin.
Heat resistance
No dimensional change even in the high temperature range due to superb heat resistance
Sumo wrestlers are resistant to heat and do not give up at all. Basically, foams can withstand temperatures up to 80°C. Polypropylene-based foams are not subject to dimensional change even in the high temperature range. They have excellent heat resistance with the shrinkage rate of 3% or less even at 140°C.
Workability
High workability due to excellent shape stability
Sumo wrestlers can transform into various shapes. Foams made from polyolefin, which does not deform at normal temperature and becomes soft when heated, are characterized by high workability. It is possible to stick other materials and form foams by heating and melting. Shape stability at normal temperature enables cutting into complicated shapes.
Adaptability to uneven / curved surfaces
Capable of adapting to any surface to fill gaps
The spongy and soft body of sumo wrestlers can adapt to and fill any gaps. Due to their flexibility, foams can adapt to curved, uneven, or sharp surfaces to fill gaps. When used as sealing materials, such as tapes, foams fill gaps with surfaces and demonstrate a high sealing performance.
【New domain】Thermal conductivity
Realizing high thermal conductivity based on the proprietary forming process
Sumo wrestlers have acquired flexible bodies with a high metabolic rate through SEKISUI’s original training. High thermal conductivity and flexibility have been realized by forming optimal heat dissipation paths based on SEKISUI’s proprietary forming technology. Made solely from insulation materials, the products pose minimal defect risks to electronic parts. Thus, the products are also suitable for automotive applications which require high reliability. * The products have a new structure instead of the foam structure.
Applications of foam
Electronic devices underpinned by ultra-thin foams
Foams are used in smartphones. They are used for protection of cameras, speakers, and connectors inside smartphones due to their adaptability to uneven surfaces and waterproof/dustproof performance (equivalent to IPX5). Thinness, which is the most important characteristics of SEKISUI’s foams, contributes to miniaturization of electronic devices.
Functions
Waterproof/dustproof performance
Thinness
Adaptability to uneven
Tapes for adhesive bandages that fit the human skin
One of the most familiar applications of such foams is the tapes for adhesive bandages used for abrasions, etc. They have affinity to the human skin due to their flexibility to adapt to the skin, surface smoothness, and oil resistance.
Functions
Oil resistance
Surface smoothness- Adaptability to curved surfaces
Foams that maintain high thermal insulation performance
Foams are used as thermal insulation materials for air conditioning ducts, etc. They ensure both high thermal insulation performance and flame retardance and are easy to process. The high waterproof performance helps maintain high thermal insulation performance. They have been used in various regions with different weather conditions, and their performance has been demonstrated under different use conditions.
Functions
- Water resistance
Thermal insulation performanc
Workability
Improving comfort of a space by the sound insulation performance
Foams are used for ceilings of factories (metal roofs). The high impact absorbing performance suppresses the sound of rain drumming on metal roofs, thereby improving comfort. Foams for ceilings have adhesive layers for easy installation.
Functions
Impact absorbing performance
Sound insulation performance- Workability
Absorbing impact to protect displays
Foams are also used for displays in smartphones. They protect displays with excellent impact absorbing performance. They are also suitable for preventing pooling (rainbow-colored ripples) when you put your finger on a liquid crystal panel. The thinness, which is among the smallest in the industry, and excellent performance contribute to improving the design quality and functionality of cutting-edge devices.
Functions
- Impact absorbing
- Thinness
Absorbing impact as floor substrates
Foams are used as floor substrates. The impact absorbing performance of foams demonstrates moderate rebound resilience and sound insulation performance, making the foams suitable for floor substrates. They serve as essential components to improve the comfort of a space.
Functions
- Impact absorbing performance
- Sound insulation performance
High workability contributing to automotive interiors
Foams are used for various automotive interiors, including instrument panels. Dimensional change is minimal at high temperature of 120°C. Foams can withstand high temperature during forming due to superb heat resistance, enabling a deep drawing process in vacuum forming.
Functions
Heat resistance- Workability
Introduction of products
SOFTLON™
This is the standard grade that can be used for all purposes, such as cushioning, thermal insulation, and interior materials. We offer a lineup of products with heat resistance, flame retardance, formability, and other characteristics.
S Series
Standard PE foams with high basic performance
NF Series
Suitable for high-temperature environments with excellent heat resistance and thermoformability
FR-ND Series
Thermal insulation and cushioning foams with excellent flame retardance conforming to standards of UL, FMVSS, rolling stock, etc.
IF Series
Suitable for tape bases, etc. with improved expandability and strength
SP Series
PP foams with improved heat resistance and rigidity suitable for vehicle parts materials
THIN TYPE
This is the thin grade with thinness, which is among the smallest in the world, as well as strength and softness. It is suitable for base materials for various tapes as well as gaskets and cushioning materials for highdefinition electronic devices.
VOLARA™
A thin and flexible foam used as the base material for highly functional tapes. It is a base material for thin tapes that inherits the high-standard performance of SOFTLON™ S.
XLIM™
An ultra-thin foam whose thinness is among the smallest in the industry (0.06 mm). Thinness, excellent functionality, and reliability are realized. The product contributes to improving the design quality and functionality of cutting-edge devices, including smartphones.
XLIM™-HR
Heat-resistant thin foams. This is the thin, heat-resistant grade with both flexibility and rigidity. Dimensional change is minimal at high temperature of 120°C. Production is possible from 0.1 mm. Excellent formability and workability are also realized.
THERMOBREAK™
This is a cutting-edge and most innovative high-performance thermal insulation material that can be used for HVAC systems for buildings and HVAC systems for rolling stock around the world.
LS-FMP
Realizes easy installation. A thermal insulation material certified for the Japanese fire and smoke standard by the Ministry of Land, Infrastructure, Transport and Tourism. Sheets and tubes for thermal insulation of air ducts and pipes.
NO-CLAD
High functionality that does not require drawing. A thermal insulation material with special weather-resistant coating on the aluminum surface. Installable for external applications without racking. Sheets for thermal insulation construction of external air ducts and tubes for thermal insulation construction of external pipes.
RT
The product improves comfort and safety for passengers.It is a thermal insulation material for HVAC systems for rolling stock. It conforms to international standards on flame retardance and smoke emissions for rolling stock, such as EN45545-2 and NFPA130.