Method for controlling bacterial growth in process water
A system for reducing or preventing the growth of organisms in the process water used to coat glass fibers using a formaldehyde-free chemical composition. One or more biocides is inserted into the process water which mitigates the growth of microbes in water. The biocides are added in an amount adequate to minimize expansion of organisms without negatively affecting the application of the binder composition to the glass fibers.
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Fiberglass binders have many different applications which range from stiffening applications at which the binder can be applied to woven or non-woven fiberglass sheet goods and cured, making a stiffer merchandise; thermo-forming software wherein the binder resinis applied to sheet or even lofty fibrous item following which it is dried and optionally B-staged to form an intermediate although nonetheless curable merchandise; and to fully cured systems like building insulation.
Fibrous glass insulation products normally contain pre-assembled glass fibers bonded together by a cured thermoset polymeric material. Molten streams of glass have been drawn into fibers of random lengths and turned right into a forming chamber in which they arerandomly deposited as a mat on a traveling conveyor. The fibers, while in transit at the forming chamber and while still hot in the drawing performance, are sprayed with an aqueous binder. A phenol-formaldehyde binder is currently used throughout thefibrous glass insulation industry. The residual heat in the glass fibers along with the flow of air through the fibrous pad during the forming operation are generally enough to volatilize most to all of the water from the binder, thus leavingthe remaining elements of this binder on the fibers as a viscous or semi-viscous high solids liquid. The coated fibrous pad has been transferred into a curing oven in which heated atmosphere, for example, is hauled through the mat to cure the binder and rigidly bond theglass fibers together.
Fiberglass binders used in the present sense should not be confused with matrix resins which are a completely different and non-analogous area of art. While sometimes termed”binders,” matrix resins behave to fill the entire interstitial spacebetween fibers, resulting in a dense, fiber reinforced 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 only the fibers, and particularlythe junctions of fibers. Fiberglass binders also can’t be equated with wood or paper product”binders” where the glue properties are tailored to the chemical nature of their cellulosic substrates. Many such resins, e.g. resorcinol/formaldehyderesins, are not suitable for use as fiberglass binders. One skilled in the art of fiberglass binders wouldn’t look to cellulosic binders to fix any of the known problems associated with fiberglass binders.
Binders useful in ceramic insulating material generally require a low viscosity in the uncured state, yet have characteristics to form a rigid thermoset polymeric mat for the glass fibers when cured. A low binder viscosity in the uncuredstate must allow the mat to be sized properly. Additionally, viscous binders are normally tacky or sticky and therefore they lead to accumulation of fiber on the forming chamber walls. This accumulated fiber may later fall upon the mat resulting in compact areasand merchandise problems.
From among the numerous thermosetting polymers, numerous candidates for suitable thermosetting fiberglass binder resins exist. But, binder-coated fiberglass products are often of the commodity type. Therefore, price becomes a driving variable,generally ruling out such resins as thermosetting polyurethanes, epoxies, and others. As a result of their excellent cost/performance ratio, the resins of choice in the past are phenol/formaldehyde resins. Phenol/formaldehyde resins can be economicallyproduced, and can be extended with urea before use as a binder in several applications. Such urea-extended phenol/formaldehyde binders are the mainstay of the fiberglass insulation sector for ages.
Within the last few years, however, minimization of volatile organic compound emissions (VOCs) both on the part of the industry desiring to offer a cleaner environment, in addition to by Federal regulation, has led to extensive investigationsinto not just reducing emissions in your present formaldehyde-based binders, but also into candidate replacement binders. For example, subtle changes in the ratios of phenol to formaldehyde in the preparation of their simple phenol/formaldehyde resoleresins, changes in catalysts, and addition of different and multiple formaldehyde scavengers, have resulted in significant progress in emissions from phenol/formaldehyde binders when compared with binders previously utilized. However, with morestringent federal regulations, more attention was paid to other binder systems that are free from formaldehyde.
One especially useful formaldehyde-free binder system uses 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 amounts of formaldehyde as a result of drying or curing. Formaldehyde-free resins don’t emit appreciable levels of formaldehyde through the insulation production process and don’t emit formaldehyde under normal serviceconditions. The use of this binder system in conjunction with a catalyst, like an alkaline metal salt of a phosphorous-containing natural acid, which results in glass fiber products which exhibit excellent recovery and rigidity properties.
An inherent advantage of phenolic-based resins is that the natural biocide features of formaldehyde. As used herein, the expression”biocide” refers to agents that kill or destroy organisms in addition to materially inhibit the rise of organisms.Formaldehyde-free chemical systems, like a system containing a polycarboxy and a polyol, don’t have this kind of natural biocide characteristic. Thus, use of formaldehyde-free binders ends in process water systems getting overrun with growingorganisms. As a consequence of high levels of harmful organisms from the process water, plant personnel are exposed to a risk of adverse health consequences. Additionally, some organisms may cause corrosion of process equipment and piping, requiring expensive repairsand replacement and gets the capacity to efficiently control the process. Also, a high degree of organisms may cause congestion of process lines. Thus, preventative measures need to be taken to significantly reduce or eliminate entirely the organismsin the process water.
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