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A greater focus on air quality has arisen, not only on the emissions of the vehicles we drive, our factories and our manufacturing facilities, but also our HVAC systems, carpets, wall coverings and even now furnishings. Chemical sensitivity has evidenced itself in ever greater numbers over the past decade. An awareness and in-depth analysis of the issues involved has begun.

The importance of understanding resins, relates primarily to out-gassing issues. For all composite panel products, resins are utilized as binding agents for the various particulates. These resins pose certain potential risks - Certain resins, such as urea formaldehyde, continue to outgas after initial cure, enabling a potential exposure to unnecessary potentially harmful toxins. There is a great movement within the Design and Environmental community to eliminate the use of urea formaldehyde from the interior environment by substituting for other binding agents. The elimination of added urea formaldehyde from newly constructed environments is a goal considered credit worthy by the LEED rating system of the USGBC.

Out-gas chamber tests of particle board panels that utilize urea formaldehyde as a binder completely sealed on six sides with appropriate sealers and topcoats have provided results of no detectable out-gassing of urea formaldehyde. This is not an effective preventative method, as a concern results should the seal be broken, as in the use of a grommet for wire passage on a work top.

So far, substituting resins with alternative binders has proven the only solution for this issue. For availability and cost impacts see Substrates Composite Panels. As studies of this issue continue and more research is applied, we strive to stay abreast, and update this site as this topic affects us all.

Resin Types
Defined by Fiber Futures

The main types of resin used in composite fiber product manufacturing include:
1) MDI; 2) Urea-Formaldehyde; Phenol-Formaldehyde and; 4) Polyurethane.

Products made of urea formaldehyde can release formaldehyde gas; products made of phenol formaldehyde generally emit lower levels of the gas. An emerging class of “bio-based” adhesives derived from plant materials (primarily soy) are also worth examining, however, none are yet available on a competitive commercial basis.

MDI isocyanate is a newer resin (compared with UF and PF) that has gained market share partly in response to public concern over formaldehyde emissions. MDI is used in most of the strawboard plants. MDI is a liquid binder based on 100% active ingredients. It is a very efficient resin, due to the fact that it makes a molecular and an adhesive bond. This also has drawbacks, in that it can stick firmly to metal and various parts of the human anatomy. It does not off-gas after use. However, workers must take great care in the production of the resin itself, as it is highly volatile and has no odor. Major producers of MDI include Dow Chemical and BASF. MDI tends to be more expensive than the formaldehyde resins and it is shipped in liquid form, so the cost of MDI has risen nearly 15% over the past year.

Urea-Formaldehyde (UF) is a colorless, pungent-smelling gas that can cause negative effects to sensitive people. Sensitivities can include watery eyes, burning sensations in the eyes and throat, nausea, and difficulty in breathing in some humans exposed at elevated levels (above 0.1 parts per million). High concentrations may trigger attacks in people with asthma. According to the EPA, it has also been shown to cause cancer in animals and may cause cancer in humans.

Phenol-Formaldehyde (PF) is a red/black-colored resin used in pressed wood products such as softwood plywood and flake or oriented strandboard for exterior construction. Although formaldehyde is present in both types of resins, pressed woods that contain PF resin generally emit formaldehyde at considerably lower rates than those containing UF resin.

Polyurethane is used to produce rigid foams, flexible foams, sealants, coatings, elastomers and agrifiber binders. Applications for these products cover a wide range of end uses, including cushioning for furniture and bedding, carpet backing, automotive seating and instrument panels, office furniture, flooring, and insulation for appliances, sheathing and roofing.

 


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