Q&A Frequently Asked Questions
We will answer your questions about urethane, from simple to specialized.
What is flexible urethane foam? (raw materials, properties, manufacturing method, features, applications, etc.)
What is soft urethane foam?
Urethane foam (commonly referred to as "poly" for short) is made by mixing polyol and polyisocyanate as the main ingredients with a blowing agent, foam stabilizer, catalyst, colorant, etc., and foaming it while resinifying it, and those with interconnected cells that are soft and resilient are called "flexible urethane foam." Used in car seat cushions and mattresses, it is a lightweight plastic foam with an expansion ratio of approximately 60 to 10 times and an apparent density of 16 to 100 kg/m3.
In addition, there are two types of urethane foam: "rigid urethane foam," which is a closed-cell, hard, and non-resilient foam used primarily as insulation, and "semi-rigid urethane foam," which has intermediate properties and is primarily used as a shock-absorbing material.
Where is flexible urethane foam used?
Flexible polyurethane foam has the following uses:
| classification | Application example | |
|---|---|---|
| soft | Four-wheeled vehicles | Seat cushions for automobiles, construction machinery, railway vehicles, etc., cover fabric laminate lining materials, shock-absorbing materials for door trims and center pillar garnishes, sealing materials, sound-absorbing and vibration-damping materials for floors and ceilings, etc. |
| Two wheel vehicle | Saddles, air filters, oil filters, helmet linings, rider cushions | |
| device | Various sound-absorbing materials, air conditioning filters, liquid-tight and air-tight seal materials, soundproof flooring materials | |
| furniture | Chairs, floor chairs, sofas, cushions | |
| bedding | Mattresses, comforters and futons, pillows, bed pads | |
| Interior | Cushions, various cushions, carpet and mat backing, kotatsu mats and covers | |
| packaging | Precision equipment, food and fruit packaging materials, fresh fish tray mats | |
| Daily necessities | Kitchen foam, body soap foam, shoe polish foam, car wash foam, diaper side gathers, shoe (upper lining, insole, inner boots), slipper core, stuffing for stuffed toys, cosmetic puffs | |
| for clothing | Shoulder and bra padding, cold weather liner | |
| Others | Soil for raising seedlings and gardening, materials for hydroponic cultivation, shock-absorbing walls for fences, landing mats for exercise, mannequin bodies, cushions for boat seats, play balls, sound-absorbing materials for acoustic rooms, cushions for wheelchairs, heat-retaining and insulating materials | |
| semi-rigid | Vehicle others |
Instrument panels, armrests, headrests, sun visors, steering wheels, cushions and backs for aircraft |
What is the difference between polyether foam and polyester foam?
Flexible urethane foams are divided into "polyether foam" and "polyester foam" depending on the type of polyol used. In general, "polyether foam" can be blended with a wide range of raw materials, allowing it to be given a wide range of performance characteristics such as elastic modulus and cushioning to suit the application. For this reason, it is used in a wide variety of applications, including cushioning for mattresses and chairs. "Polyester foam" has excellent oil resistance, abrasion resistance, and mechanical strength, and the cell diameter can be easily changed, so it is used for special applications such as foam materials and filter materials.
How is flexible polyurethane foam manufactured in factories?
At the manufacturing plant, it is produced in the form of "slabs" or "molds".
"Slab" products are made by running the mixed liquid on a continuous conveyor, causing continuous foaming, usually in the shape of a square or kamaboko cross section, 1-2m wide and 0.3-1m high, and then cutting it into large loaf-shaped pieces of the specified length (usually 1-2m).It is shipped to processing plants in this form, and products of various shapes can be cut and processed from the slab.
"Molded" products are made by injecting the concentrate into a plastic or metal mold, foaming it, and then removing it from the mold, allowing for the mass production of products with complex shapes with high dimensional precision. "Polyester foam" has excellent oil and abrasion resistance and mechanical strength, and the diameter of the air bubbles can be easily changed, so it is used for special purposes such as foam materials and filter materials.
What are the features of flexible urethane foam?
- (1) It can exhibit a wide range of appropriate properties and physical performance according to requirements.
By selecting the combination, mixing ratio, manufacturing conditions, etc. of polyols, polyisocyanates, foaming agents, foam stabilizers, colorants, and other compounding agents, it is possible to provide the performance required for a variety of applications.In other words, it exhibits features such as light weight, good cushioning performance, durability, shock absorption, heat insulation, heat resistance, chemical resistance, sound absorption, and a wide range of coloring options.
For example, when it comes to cushioning, urethane foam is lighter than metal springs, cotton, or felt, but has excellent "cushioning performance" with high elasticity and less settling, and is easy to handle. Furthermore, using urethane foam in car seats contributes to curbing global warming by reducing weight. Recently, in response to health trends, it has also been given distinctive properties such as antibacterial properties and low-resilience properties. - (2) It can be cut and molded into various shapes.
Flexible urethane foam can be easily cut into straight lines, irregularities, curved surfaces, and hollowed out, and can be freely processed into any desired shape, from thin sheets to regular shaped products. It can also be molded using a heat press. When free design, dimensional precision, and mass production are required, such as for automobile seats, "molded products" that are foamed inside a mold can also be selected. - (3) Various bonding and integration methods can be selected depending on the application.
In addition to foams themselves, they can easily be integrated with metals, fabrics, leather, etc. by sewing or adhesive. "Frame lamination," in which the foam surface is momentarily exposed to a flame to melt it, forming an adhesive layer with polyurethane to bond the materials together, creates a nice texture and improves productivity.
As mentioned above, flexible polyurethane foam has significant advantages over other plastic foams, similar fiber materials (cotton, felt), springs, etc., and is therefore used in a wide range of applications, from automobiles and household items to industrial and construction materials, with quality improvements and expansion of applications continuing to this day.