Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1995-01-05
2002-08-27
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S129000, C528S230000, C524S596000, C524S598000, C524S818000, C524S841000
Reexamination Certificate
active
06441122
ABSTRACT:
FIELD OF THE INVENTION
The subject invention pertains to binders suitable for use in fiberglass products, which incorporate minor amounts of melamine in urea-extended phenol/formaldehyde compositions. More particularly, the subject invention pertains to water-soluble binders containing urea-extended phenol/formaldehyde alkaline resoles to which minor amounts of melamine have been added, and to fiberglass products treated with these binders. Use of the binder compositions of the present invention result in fiberglass products having enhanced characteristics.
BACKGROUND OF THE INVENTION
Fiberglass comes in many shapes and sizes and can be used for a variety of applications. A general discussion of fiberglass manufacturing and technology is contained in
Fiberglass
by J. Gilbert Mohr and William P. Rowe, Van Nostrand Reinhold Company, New York 1978, which is herein incorporated by reference. During the preparation of fiberglass, whether by a blown fiber or continuous filament manufacturing process, the resulting glass fibers may easily be degraded in their strength characteristics by the self-abrasive motion of one fiber passing over or interacting with another. As a result of this self-abrasion, surface defects are caused in the fiberglass filaments resulting in reductions in overall mechanical strength. Furthermore, fiberglass which is destined for use as building insulation and sound attenuation is often shipped in a compressed form to lower shipping costs. When the compressed bundles of fiberglass are utilized at the job site, it is imperative that the fiberglass product recover a substantial amount of its precompressed thickness. Otherwise, loss of insulation and sound attenuation properties may result.
Traditionally, fiberglass has been treated with phenol/formaldehyde resole binders to alleviate the previously-mentioned defects. The phenol/formaldehyde binders utilized in the past have been the highly alkaline resole type which have the combined advantages of inexpensive manufacture and water solubility. Typically, the binders are applied to the fiberglass from aqueous solution shortly after the fibers have been produced, and cured at elevated temperature in a curing oven. Under the curing conditions, the aqueous solvent is evaporated, and the phenol/formaldehyde resole cures to a thermoset state. The fibers in the resulting fiberglass product are thus partially coated with a thin layer of thermoset resin, which tends to accumulate at the junctions where fibers cross each other. The resulting product therefore not only suffers from less self-abrasion, but also exhibits higher recovery than a fiberglass product not incorporating a binder.
The alkaline phenol/formaldehyde resoles contain a fairly large excess of formaldehyde from the manufacturing process. This excess of formaldehyde has been taken advantage of by adding urea to the phenol/formaldehyde resole, resulting in a urea-extended resole. Urea-extended phenol/formaldehyde binders are more cost-effective than the straight phenol/formaldehyde resins, but exhibit some loss in properties as the urea content increases. Thus, efforts have been made to incorporate other resins which can enhance the properties of the binder.
For example, in U.S. Pat. No. 3,819,441, fiberglass binder compositions containing highly-advanced phenol/formaldehyde resole resins which are insoluble in water at a pH of between 7 and 8 have been utilized. The insoluble resoles are optionally extended with melamine, dicyandiamide, or urea, acidified, and mixed with a surfactant, following which the resin is dispersed in water and applied to glass fibers. The high degree of advancement requires extended processing time in preparing the resole, thus increasing manufacturing costs, and the water insolubility requires addition of a surfactant. Furthermore, as the aqueous binder composition is a dispersion rather than a solution, it may suffer from traditional defects of dispersions, i.e., non-uniform composition, susceptibility to settling or phase separation, and plugging of spray nozzles. In addition, the dispersion cannot uniformly coat the glass fibers in the applied state, and must rely on fusion of the resin composition and subsequent flow prior to cure to effect the same type of coverage that can be obtained from alkaline resole solutions.
An anti-punking resin, and fiberglass products treated therewith, are described in U.S. Pat. Nos. 3,907,724 and 3,919,134. The resin disclosed in these references is prepared at low formaldehyde to phenol ratios under alkaline conditions following which it is modified with large amounts (15% or more) of melamine or dicyandiamide, optionally additionally with urea. Etherified methylol melamine in the amount of at least 10 weight percent is then added. The resulting resin composition is only modestly water tolerant, and proteinaceous dispersants are added to maintain stable dispersions at higher dilution. The use of a large amount of melamine and etherified methylol melamine makes preparation of these binders expensive, and the necessity of the use of a proteinaceous dispersant not only increases the cost, but renders the treated fiberglass susceptible to growth of microorganisms. As the resulting composition is a dispersion rather than a solution, it suffers from the defects of dispersions previously noted.
An anti-punk resin system employing a novolac resin as a starting material for a resole is described in U.S. Pat. No. 3,956,204. Phenol and less than equimolar formaldehyde are reacted under acidic i|conditions to form a water-insoluble novolac containing a high proportion of dihydroxydiphenylmethane isomers. Following preparation of the novolac, excess formaldehyde is added to form a resole, following which a nitrogenous substance (greater than 20 weight percent calculated on the basis of melamine) is reacted and optionally extended with urea, following which the pH is adjusted to between 7 and 8. Crystallization of the resole is prevented by the presence of 2,2′- and 2,4′-dihydroxydiphenylmethanes which are present in the mixture due to the formation of the initial novolac under the required acidic conditions. Example 1 of the patent illustrates that traditional one-step alkaline process resoles are unsuitable for this application. The necessity of using a multistage reaction is undesirable economically, and the large amount of melamine increases the cost.
In U.S. Pat. No. 4,285,848, is disclosed a wood adhesive prepared by sequential reaction of phenol with a large excess of formaldehyde under acidic conditions, followed by subsequent reaction under alkaline conditions. Melamine is then added in large amounts (100 to 160 mole percent based on phenol) and reacted at elevated temperature, following which urea is added, again at elevated temperature. The reaction sequence is stated to be critical, and water tolerance is unspecified. The multistage reaction conducted at elevated temperature and the relatively large amount of melamine result in a higher cost product.
In U.S. Pat. No. 4,324,833, is disclosed a wet process mat binder incorporating a phenolic resin extended with urea, a partially methylated melamine formaldehyde resin, and polyvinyl alcohol, deposited on fiberglass at a pH within the range of 3.5 to 6.5, with starch as an extender. Incorporation of methylated melamine formaldehyde resin and polyvinyl alcohol result in a product of higher cost. The use of starch as an extender, as with proteinaceous dispersants, renders the product potentially susceptible to attack of microorganisms.
In U.S. Pat. No. 5,296,584, are disclosed fiberglass binders containing alkaline resoles to which melamine is added in such a manner that it is dispersed but not reacted, and the resulting dispersion rendered acidic. It is further disclosed that the melamine “cures” with the resole by being solubilized in the resole components at elevated temperature and cross-linking. Cross-linking is said not to occur at neutral or elevated pH, requiring the final pH to be acidic. The resulting dispersions are useful as a
Aspholm Glenn S.
DeMott Gerard J.
Taylor Thomas John
Johns Manville International Inc.
Rajguru U. K.
Seidleck James J.
Touslee Robert D.
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