Innovations in Carpet Pad (Cushion) Manufacturing
The carpet pad, or carpet cushion in the cushion manufacturing industry, offers a diverse range of cushion styles. These cushions cater to various comfort and performance needs. Cushions are crafted using both synthetic and man-made fibers for durability, support, and enhanced flooring longevity.
Carpet pads contribute to overall floor performance. They improve insulation, sound absorption, and wear resistance. Whether designed for plush underfoot comfort or high-traffic resilience, they serve a vital purpose.
With advancements in materials and technology, manufacturers continue to innovate, providing options tailored to residential and commercial applications.
Carpet Cushion is Environmentally Friendly
Today, much of this cushion is produced from recycled materials. The carpet cushion industry has become green. They continue to become more and more environmentally friendly with their carpet pad manufacturing techniques.
- Bonded cushion from trim generated by polyurethane fabrication facilities that serve industries like furniture and bedding.
- Natural felt cushion is routinely manufactured from recycled burlap bags.
- Synthetic felt cushion is manufactured with recycled carpet waste as its major part.
- Textile fiber cushion is made from recycled clothing and other post-consumer textile fibers.
The Truth About Urethane Carpet Pad: It’s Not What You Think
Urethane or polyurethane carpet cushions represent the greatest number of cushion products used for carpet pad manufacturing. Most of us would believe that urethane or polyurethane cushion holds a blend of the chemical urethane.
There is No Urethane Chemical in Urethane Cushion
The fact is, there is no urethane chemical in a urethane cushion. This is not a conspiracy of the carpet pad manufacturing business. The carpet pad manufacturing industry uses the name urethane as used in the plastics industry. Urethane has been designated due to the repeating units of its structure, which resemble the chemical urethane.
How Urethane Cushion Got it’s Name
Urethane in the plastics industry gets its name because it is generally a polymer connected by urethane groups. Urethane linkage and its supplements result from the reaction of polyol and isocyanate. The chemical urethane is a colorless, crystalline substance. It is used primarily in medicines, pesticides, and fungicides. This information is not used every day. It is of little interest to the end-user. Nonetheless, a professional should be aware of it should the situation arise.
Understanding Prime Carpet Pad
The word prime often suggests it is the “best.” Yet, in the carpet pad manufacturing industry, prime refers to a group of cushion products. These products all share particular characteristics. These products include:
- conventional prime
- grafted prime
- densified prime
Producing Prime Urethane Cushion
Carpet pad manufacturing of prime cushion products uses flexible polyurethane foam slabstock chemistry. Support, durability, and firmness characteristics are routinely enhanced by chemical additives. Color is routinely added to the chemical mixture to give identity to products.
Prime cushion is produced by mixing water, conventional polyols and isocyanates to start a rapid chemical reaction. This results in carbon dioxide gas, which forms tiny bubbles throughout the liquid mixture. As the gas expands, the polymeric mixture rises like a loaf of bread. The bubbles that form by this reaction will quickly burst. This allows the carbon dioxide to escape from the foam. It leaves behind a uniform cellular structure. The chemical’s mixture is then developed into slabstock or logs.
Slab Stock Production Process
The slabstock production process is continuous. The reacting foam chemical mix is dispensed onto a moving conveyor belt. The expanded foam develops in long flat loaves or buns (normally six feet wide). The buns are slit to the desired size, much like you would slice a loaf of bread.
Log Style Production Process
The log production process involves developing the urethane in a cylinder shape referred to as a log. These polyurethane logs are peeled into the desired thickness, much like you peel plywood veneer from a log.
Cushion Facing
Both the slit (slab stock) and peeled (logs) varieties are used. A facing material referred to as scrim is laminated on one side. This provides stability. It also creates a surface for the carpet to be stretched across. The lamination process bonds the foam and scrim together into a single composite.
Bonding of facing material is accomplished through adhesives or through heat processes like flame lamination (also known as flame bonding). This bonds the foam to a fabric or other material (film, etc.). This process melts one surface of the foam with a flame source. The melted surface is then quickly pressed to the other substrate. This must occur before the melted material resolidifies.
Conventional Prime Cushion
This is the basic prime cushion and shows the basic industry technology. It is much softer. It has many air-filled compartments with multiple open windows. These windows are formed by the surrounding network of elastic struts. This product will not work as well as the better prime products.
Densified Prime Cushion
This cushion provides a unique under foot feel. With densified prime the vertical compression is limited by the oriented cell thickness. In densified prime, vertical struts are stunted. The cell shape is flattened in directional orientation. The vertical compression is limited by the oriented cell thickness at a specified firmness. This is accomplished through controlling the foam rising action through mechanical or chemical technologies.
Grafted Prime
In this cushion, part or all of the conventional polyol is substituted with a special polyol. This special polyol is referred to as a polymer polyol, graft polyol, or copolymer. It holds minute polymer particles of styrene and other monomers. This composition extends the harness range beyond that of conventional prime. By exchanging or adding these reinforced polyols, the hardness range of a grafted prime increases significantly. It extends far beyond that of the conventional prime products.
Selecting Prime Urethane Cushion
Prime urethane carpet cushions are manufactured in a variety of products of varied density and firmness. They are normally produced in 6-foot widths in thicknesses of 1/4″ to 9/16″. Of these products, the Cushion Council states: “The best products have the right balance of properties for comfort.” They also ensure durability. For a stretched carpet, this would be a quality cushion that is firm and not thicker than 7/16 inch.
Mechanically Frothed Urethane Foam
Frothed urethane foam cushions are made from a process originally developed to apply cushioned backings to carpet. Air bubbles are introduced by mechanically beating the chemical solution. The solution is solidified by heat and then fabricated into sheets of a predetermined thickness. A facing material is laminated on one side to provide stability. It creates a surface for the carpet to be stretched across. Urethane foam cushioning is applied to a sheet of non-woven material. This forms a carpet cushion product. It typically has a higher density and firmer feel.
What is High Resilience (HR) Foam?
This is a variety of polyurethane foam produced using a blend of polymer or graft polyols. High resilience foam has a less uniform (more random) cell structure different from conventional products. The different cell structure helps add support, comfort, and resilience or bounce. High resilience foams have a high support factor and greater surface resilience than conventional foams and are defined in D3770.
Selecting Bonded Urethane Cushion
Bonded Urethane Foam (Rebond)
Bonded foam cushions are also known as rebond. They are made by combining shredded or chopped pieces of scrap. This is done through a fusion process into a single sheet of material. Many grades of bonded cushion are considered to be among the best performing and highest quality carpet cushion products.
Bonded cushion production starts with scrap that is a by-product of foam manufactured for furniture, mattress, auto and other uses. The scrap is sorted by quality and mixed with resins. The mixture is pressurized and injected with steam to form a large block or foam cylinder. The block or cylinder is slit or peeled to its desired thickness. It is during the sorting and steaming stage that significant differences in bonded polyurethane cushion quality emerge.
Generally, a cushion that steams longer will be of better quality. This is compared to one that has moved through this process at a quick pace. Soft scrap without hard pieces and lumps will generally compact better and produce a better cushion.
The CRI (Carpet and Rug Institute) recommends a minimum density of 5# for bonded urethane. The minimum thickness should be 3/8″ for residential installation. The maximum thickness is 7/16″ for light traffic and 6.5# for heavier residential traffic. As these are minimum guidelines, one would be wise to consider upping that to a minimum of 7#. For a commercial installation the density should be at least 12# for optimal performance.
A bonded urethane foam pad wears less well when its thickness increases above about 3/8″. The wear value also decreases as the pad becomes less firm. Therefore, when you compare the density of the cushion, also compare the composition. Check the firmness to make sure that you are selecting a densely compacted product. Ensure it is not full of heavy scrap and voids, or very soft with little resilience.
Fiber Cushions (Felted)
Varieties of this type of cushion are produced from both natural and synthetic fibers. Natural fibers include animal hair, jute, hair & jute blends and rubberized hair and/or jute. Many of the cushions contain recycled material such as jute reclaimed from various forms of burlap.
Synthetic fibers include nylon, polypropylene, and polyester. These cushions are most commonly used under commercial carpet and some Berber carpet. They are made in widths up to 12′ and in weights from 32 to 85 ounces per square yard.
Both natural and man-made fiber cushions are produced in a couple of different ways. Some are manufactured by a process. This process basically steams and presses the materials. They become matted into a flat, uniform, felted like surface.
Other cushions of this variety are produced by intermingling. They go through a needle-bond process, much like that of felt-like outdoor carpets. The needle-bonded products are smoother and easier for the installer to cut.
Natural and man-made fiber cushion grades are measured by weight in ounces per square yard. When using a fiber or felted style cushion you should not exceed a thickness of 7/16″.
A fiber pad should never be too thick or too low in density. If a thick felted pad is more expensive than a thin felted pad, it has a decreasing value-to-wear ratio. This is an observed fact. This occurs as it exceeds about 7/16″ in thickness. It also has a decreasing value-to-wear ratio as the density decreases below about 48 ounces per square yard.
Sponge Rubber
Flat Sponge (Slab Rubber) has a flat surface without ripples.
Rippled Sponge (Waffle Rubber) has a rippled or waffled surface.
Sponge cushion is manufactured with both synthetic and natural rubber, along with other chemicals that include both oils and fillers. The mix expands when air is chemically introduced into the batch. It is then formed into either a flat or rippled slab.
A material is bonded to the surface. This adds stability. It provides a surface that the carpet can be stretched over.
These cushions are made in widths up to 12′ and in weights between 41 and 120 ounces per square yard.
Double Stick Cushions
A variety of cushions from sponge to needle-bond synthetics have been produced for these installations. On double stick installations it is important that the carpet manufacturer’s specification for carpet cushion has been adhered to.
Carpet Cushion Council Recommendations
The Carpet Cushion Council is an industry leader in carpet pad manufacturing. Following are four of their carpet pad recommendations.
1. The heavier the traffic, the thinner the cushion. In heavy traffic areas like hallways, stairs, and rooms with lots of activity, choose thinner (3/8 inch and less) cushion. Rooms with heavy furniture, such as dining rooms, also require heavier cushion to better protect the carpet.
2. Use thicker and more resilient cushions for bedrooms, dens, and areas for a more luxurious feel is desired. But again, it’s best to choose higher ounce weight. Opt for higher density products. These choices help make the carpet last longer.
3. Visual appearances of cushion are nice, but remember, once it’s installed, you’ll never see the cushion again. Pay more attention to ounce weights, densities, and thickness when buying.
4. Don’t scrimp. Remember, your new floor covering is a system of both carpet and cushion. If you cut corners on cushion, you could be cutting the usable life of your carpet.
For more information of carpet cushion Carpet Cushion Council
