Method for controlling bacterial growth in process water
A system for preventing or reducing the development of organisms from the process water used to coat glass fibers with a formaldehyde-free binder composition. One or more biocides is added to the process water which mitigates the growth of microbes in the water. The biocides are added in an amount sufficient to minimize expansion of organisms without negatively affecting the use of the binder composition to the glass fibers.
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Fiberglass binders have many different uses ranging from stiffening applications where the binder can be applied to woven or non-woven fiberglass sheet products and cured, producing a milder merchandise; thermo-forming software wherein the binder resinis employed to sheet or lofty fibrous product after which it is dried and optionally B-staged to form an intermediate but yet curable merchandise; and to fully cured systems like building insulation.
Fibrous glass insulation products generally contain pre-assembled glass fibers bonded together by a cured thermoset polymeric substance. Molten flows of glass are drawn to fibers of random lengths and blown to a forming chamber where they arerandomly deposited as a pad onto a travel conveyor. The fibers, while in transit in the forming chamber and while still hot from the drawing operation, are sprayed with an aqueous binder. A phenol-formaldehyde binder is currently used throughout thefibrous glass insulation market. The residual heat from the glass fibers along with the stream of air through the fibrous pad during the forming process are generally sufficient to volatilize the majority to all of the water out of the binder, thus leavingthe remaining parts of the binder on the fibers as a viscous or semi-viscous high solids liquid. The coated fibrous pad has been transferred to a curing oven in which heated air, as an instance, is hauled through the mat to cure the binder and rigidly bond theglass fibers together.
Fiberglass binders used in the present sense shouldn’t be confused with matrix resins which are a completely different and non-analogous field of art. While sometimes termed”binders,” matrix resins act to fill the entire interstitial spacebetween fibers, leading to a dense, fiber fortified product where the matrix has to translate the fiber power properties to the mix, whereas”binder resins” as used herein are not space-filling, but instead coat just the fibers, and particularlythe junctions of fibers. Fiberglass binders also can’t be equated with wood or paper product”binders” where the adhesive properties are tailored to the chemical nature of the cellulosic substrates. Many such resins, e.g. resorcinol/formaldehyderesins, are not suitable for use as fiberglass binders. One expert in the art of fiberglass binders wouldn’t seem to cellulosic binders to fix any of the known problems connected with fiberglass binders.
Binders useful in fiberglass insulation products generally want a very low viscosity at the uncured state, yet have characteristics to make a rigid thermoset polymeric mat to your glass fibers when treated. A very low binder viscosity in the uncuredstate is required to allow the mat to be sized properly. Also, viscous binders tend to be tacky or sticky and hence they lead to accumulation of fiber onto the forming chamber walls. This gathered fiber may later fall upon the mat resulting in compact areasand product issues.
From among the many thermosetting polymers, a lot of candidates for appropriate thermosetting fiberglass binder resins exist. But, binder-coated fiberglass products are often of this commodity type. Thus, price becomes a driving variable,generally ruling such resins as thermosetting polyurethanes, epoxies, and others. As a result of their exceptional cost/performance ratio, the resins of choice in the past have been phenol/formaldehyde resins. Phenol/formaldehyde resins can be economicallyproduced, and can be extended using urea prior to use as a binder in several applications. Such urea-extended phenol/formaldehyde binders have been the mainstay of this fiberglass insulation sector for ages.
Over the past few years, however, minimization of volatile organic compound emissions (VOCs) both on the part of the industry desiring to offer a cleaner environment, as well as by Federal law, has resulted in extensive investigationsinto not only reducing emissions from the current formaldehyde-based binders, but also into candidate replacement binders. For instance, subtle changes in the ratios of phenol into formaldehyde in the preparation of their basic phenol/formaldehyde resoleresins, changes in catalysts, and addition of multiple and different formaldehyde scavengers, have resulted in considerable progress in emissions from phenol/formaldehyde binders when compared with binders previously used. Nevertheless, with morestringent national regulations, more attention has been paid to alternative binder systems which are free from formaldehyde.
One especially useful formaldehyde-free binder system employs a binder comprising a polycarboxy polymer and a polyol. As used herein, formaldehyde-free refers to resins in compositions which are substantially free of formaldehyde and/or do notliberate substantial quantities of formaldehyde as a result of drying or curing. Formaldehyde-free resins don’t emit considerable levels of formaldehyde through the insulation production process and don’t emit formaldehyde under normal serviceconditions. Use of the binder system along with a catalyst, such as an alkaline metal salt of a phosphorous-containing organic acid, which effects in glass fiber products which exhibit excellent healing and rigidity properties.
An inherent advantage of phenolic-based resins is that the organic biocide characteristics of formaldehyde. As used herein, the expression”biocide” refers to agents that kill or destroy organisms as well as materially inhibit the growth of organisms.Formaldehyde-free binder systems, like a system comprising a polycarboxy and a polyol, don’t have such a natural biocide characteristic. Thus, usage of formaldehyde-free binders ends in process water systems becoming overrun with growingorganisms. As a result of elevated levels of harmful organisms from the process water, plant employees are exposed to a risk of adverse health consequences. Additionally, some organisms may lead to corrosion of process equipment and piping, requiring costly repairsand replacement and hampering the ability to efficiently operate the procedure. Additionally, a high degree of organisms might lead to congestion of procedure lines. Thus, preventative measures will need to be taken to reduce or eliminate entirely the organismsin the process water.
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