Flexible Polyurethane Foam: a Primer F - PFA

1 Published by the Polyurethane foam Association Volume 1 | No. 1. Flexible Polyurethane foam : a Primer F. lexible Polyurethane foam is one of the most This remarkable versatility allows foam to provide versatile materials ever created. We are the support needed for long-term medical literally surrounded by it in our lives. Flexible confinement, or the comfort of pillowy It's in our cars and under our carpet. It's Polyurethane foam furniture cushioning. used as packaging material to protect is one of the most Flexible Polyurethane foam appears to delicate instruments. And it's the versatile materials ever be a simple product, but it is actually cushioning material of choice in almost created. It's used in hundreds very complex. It can be produced all furniture and bedding. In all, over of consumer products to to have an almost infinite variety of billion pounds of foam are produced provide comfort.

2 Properties. Even though two foams and used every year in the may look exactly alike, they may feel and foam has become such a widely used perform entirely differently. material because it provides a unique However, the properties of foam can be identified combination of form and function. It's light, quiet, resists and specified very precisely. The foam industry utilized mildew, and won't aggravate common allergies. foam can a number of measurements and tests to accomplish easily be cut or molded to almost any shape. At the same this. And by using these measurements, it's possible to time, foam can be made to provide very supple or very pinpoint the right foam for the right application. firm cushioning for any given application. Flexible Polyurethane foam is one of the most versatile materials ever created. It's used Auto in hundreds of Packaging consumer products Carpet Underlay to provide comfort.

3 Bedding Furniture IN TOUCH is a publication of the Polyurethane foam Association (PFA) that covers topics of interest to users of Flexible Polyurethane foam . Comfort, Support and Durability: A sofa seat cushion has to have good support, Key Ingredients to all foam comfort and durability, while the arm and Applications back cushions for the same sofa need to last and be comfortable, but won't Although a number of different Flexible Polyurethane foam necessarily be required to support measurements and tests may be used is all about much weight. The foam used to line to choose a foam to use in a given product, almost any selection task comfort, support and the case for photo equipment needs to has any or all of the following three durability. support the weight of the camera and hold up through use, but the camera elements at its final goal: cares nothing about comfort.

4 Comfort: foam cushioning has to feel good to the user and provide not just foam Production cushioning but also comfortable use. To better understand why foam properties can vary so much, it's a good idea to know something about how Support: The foam has to be able to support the proper foam is made. Flexible Polyurethane foam is produced amount of weight to properly cushion an object or from a reaction of two key chemicals, a polyol and person. an isocyanate with water. These are mixed together Durability: The foam has to hold up through use vigorously in high intensity mixers in specific amounts without losing its original properties. These are the basic with other ingredients, and the foam reaction begins benefits that foam cushioning provides, and if the needs almost immediately. Bubbles are formed, and the mixture in each of these three areas are evaluated first, selecting expands.

5 It's been compared to bread rising. In a matter the proper foam for a given use becomes fairly simple. of minutes, the reaction is complete. SUPPORT COMFORT DURABILITY. 2 IN TOUCH | Volume 1 | No. 1. Slabstock foam Process Molded foam Process Raw Material Effects IFD Measurement To manufacture foam A second method, foam The foam production process IFD is measured by indenting for cushioning, two basic molding, is a process where can be controlled through (compressing) a foam sample procedures are used. In one, individual items are produced changes in the foam raw 25 percent of its original the chemical mix is poured by pouring foam chemicals material mix. In addition to height. The amount of force onto a moving conveyor, into specially shaped molds the polyol isocyanate and (in pounds) required to indent where it is allowed to react and allowing the foam water used to produce foam , the foam is its 25 percent and expand.

6 Sides on the reaction to take place. This a variety of other chemicals IFD measurement. The more conveyor allow the foam process is used primarily and additives may be force required, the firmer to rise into a bun or slab for automotive cushioning, included based on customer the foam . Flexible foam IFD. anywhere from two to four although some contract specifications to change the measurements range from feet high. furniture utilizes molded final properties of the foam . about 5 pounds (supersoft) to cushions. These include: about 80 pounds (very firm). The continuous slab is then i Auxiliary blowing agents, which cut, stored, and allowed to augment the primary blowing cure for up to 72 hours. This agent (carbon dioxide), can be manufacturing procedure used to make foam softer or lighter. is the slabstock production process. The cured foam is i Catalysts, which speed up the subsequently fabricated into reaction to improve productivity or change foam properties.

7 Useful shapes. Most foams for use in furniture and bedding i Surfactants, which aid in the are produced this way. formation of foam cells. i Flame retardant additives, used to improve a foam 's resistance to ignition or burning. 1 ft. (Unfortunately, these tend to have a negative influence on the Water & Other comfort, support, and durability 1 ft. 1 ft. Ingredients of the foam .). The Chemical Reaction i Fillers, which increase the for Polyrethane foam weight of the foam , but can = Density possibly have a negative Isocyanate influence on the physical Mixing Head properties of the foam . By adjusting the chemical mix 65% 25%. of the foam , foam producers can manufacture literally Liquid Chemicals React to Form Solid hundreds of different types of foam , each Polyol with its own performance properties. 65% IFD 25% IFD = Support Fac IN TOUCH | Volume 1 | No.

8 1 3. Properties that Affect foam Performance SUPPORT FACTOR. There are a number of physical properties of Flexible A second IFD measurement is sometimes taken by Polyurethane foam that can be used when selecting foam indenting the foam 65 percent of its original height. This cushioning for different applications. Following is a brief second IFD measurement is used to help determine the description of the more physical properties of foam , and ability of the foam to provide deep down support. the importance of each. Physical properties of foam are Typically, the more difference between the 25 percent measured under closely controlled conditions of humidity IFD and the 65 percent IFD, the more ability the foam and temperature. Care must be taken to reproduce those has to support weight. The ratio of the 65 percent IFD. conditions when testing samples of foam for physical divided by the 25 percent IFD is called the foam 's properties.

9 Support factor. Support factors for foam range from about to The higher the number, the better the ability DENSITY. of the foam to provide support. Density is a measurement of the mass per unit volume. Foams with higher support factors offer a number of Measured and expressed in pounds per cubic foot (pcf). advantages. It is possible to specify a low 25 percent or kilograms per cubic meter (kg/m3), density is one of IFD on a foam with a high support factor to create extra the most important of all foam properties. Density is surface softness without causing the foam to bottom a function of the chemistry used to produce the foam out when weight is applied. Typically, the higher the and additives included with the foam chemistry. For foam density, the better the support factor. specification purposes, it is advisable to use the polymer density of the foam , or the density of the material made FLEX FATIGUE.

10 Up strictly by the foam chemistry without fillers or reinforcements included. (Dynamic Fatigue) There are several tests that are used to determine foam durability, or how well foam retains Density affects foam durability and support. Typically, its original firmness properties and height. Some are the higher the polymer density, the better the foam will standard laboratory tests; others are customized tests retain its original properties and provide the support and developed by different manufacturers. But virtually all comfort it was originally designed to produce. of them are based on flexing or compressing the foam a specific number of times and measuring foam firmness IFD. and height before and after testing. Indentation Force Deflection (IFD) is a measurement In flex fatigue testing, foam samples may be compressed of foam firmness.