Patent Description:
Most types of fiberglass mats produced require a binder in order to maintain the integrity of the final product. Continuous filament mat (CFM) is one such type of mat. This type of mat is produced by depositing molten glass strands directly onto a moving belt in a looping fashion. As the glass fibers cool down, a binder is applied to the mat while the CFM hardens in place. This type of mat is most commonly used in closed molding applications such as pultrusion, vacuum infusion processing, resin transfer molding, cold molding and others. In contrast, chopped strand mat (CSM) is produced by chopping continuous strand roving into short segments. These segments are then deposited on a moving belt and a binder applied to hold the fibers together.

In general terms, a binder provides a way for the fiberglass strands to bond to each other creating a more robust material, often with rigid structural integrity. As a general rule, the tensile strength of a fiberglass mat increases proportionally with the amount of binder added. The amount of binder placed on a fiberglass mat is proportionally controlled by the production line speed, which, on its part, is determined by measuring the limiting organic index (LOI). In order to achieve binder cure on a desirable time-scale, the amount of thermal initiator is varied on the initial composition. The faster the production line, the more initiator is required to achieve the desirable degree of cure.

For example, current insoluble binder compositions used on continuous fiberglass mats are primarily made out of a polyester alkyd type resin intrinsically mixed with benzoyl peroxide. As the insoluble binder concentration is increased on a fiberglass mat, more yellowing is observed. The main cause behind this coloration of the mat are the decomposition products of benzoyl peroxide and their capacity to further oxidize the fiberglass mat and/or the materials on it. Thus, there remains a need for improved binder compositions offering greater performance characteristics and better aesthetic qualities.

<CIT> discloses a composition for curing at elevated temperature comprising an unsaturated polyester, a copolymerisable monomer, and a deleterious additive. The composition for use in forming a sheet molding compound (SMC).

<CIT> discloses the use of an unsaturated polyester resin system consisting essentially of an unsaturated polyester, a copolymerisable monomer, a polymerization initiator and a gelling agent, for use in forming a sheet molding compound (SMC).

<CIT> discloses a (meth)acrylic molding material comprising (A) a (meth)acrylic polymer obtained by polymerization of monomer components essentially containing a monomer having (a) carboxyl group(s) and an alkyl (meth)acrylate monomer, and (B) one or more kinds of monomers containing a vinyl group, wherein <NUM>-<NUM> parts by weight of aluminum hydroxide and <NUM>-<NUM> parts by weight of a succinic acid derivative are added for <NUM> parts by weight of the total of said polymer (A) and monomer (B).

The invention provides improved binder compositions useful in conjunction with CFM type fiberglass mats. The compositions comprise a curable unsaturated resin, one or more azo initiators, and a flow-enhancing additive. The ingredients are then generally combined and ground into a homogeneous powder having a particle size, of for example <NUM> to <NUM>, microns, with the particle size generally determined by the intended end-use. The homogeneous powder is then either applied directly by "dusting" the fiberglass mat as it is being formed, or is mixed with water into a slurry, which in turn is applied to the mat as it is being formed. The resulting fiberglass composite structures exhibit improved whiteness over time as compared to existing compositions utilizing peroxy-type initiator systems (e.g., benzoyl peroxide).

The present invention provides compositions for binding fibers to form a continuous filament fiberglass mat, the compositions comprising (i) an unsaturated polyester or vinyl ester resin; (ii) an azo-type initiator and (iii) a flow-enhancing agent.

The unsaturated polyester or vinyl ester resin is present in an amount of from about <NUM> to about <NUM> weight percent. In certain embodiments, the unsaturated polyester or vinyl ester resin will be present in an amount of from about <NUM> to about <NUM> weight percent, or about <NUM> to about <NUM> weight percent.

In the compositions of the invention, in general, the term "unsaturated polyester" will be understood to mean a polyester made from maleic anhydride, maleic acid, fumaric acid, itaconic acid, itaconic anhydride and/or ester derivatives of these acids in combination with other carboxylic diacids and/or anhydrides, and glycols. The vinyl ester resins and unsaturated polyester resins used according to the present invention may be selected from the unsaturated polyester resins and vinyl ester resin as are known to a person skilled in the art of composites. The compositions may comprise one vinyl ester or unsaturated polyester or may utilize mixtures of vinyl esters and/or unsaturated polyesters. <NPL>), describes examples of suitable unsaturated polyester or vinyl ester resins to be used as base resin systems in the resins of the present invention, which can be subdivided into the following categories. (<NUM>) Ortho-resins: these are based on phthalic anhydride, maleic anhydride, or fumaric acid and glycols, such as <NUM>,<NUM>-propylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, <NUM>,<NUM>-propylene glycol, dipropylene glycol, tripropylene glycol, <NUM>,<NUM>-butanediol, <NUM>,<NUM>-hexanediol, <NUM>-methyl-<NUM>,<NUM>-pentanediol, neopentyl glycol or hydrogenated bisphenol-A. (<NUM>) Iso-resins: these are prepared from isophthalic acid, maleic anhydride or fumaric acid, and glycols. (<NUM>) Terephthalic resins: these are prepared from terephthalic acid, maleic anhydride or fumaric acid, and glycols. This class of resins also includes resins in which poly(ethylene terephthalate) is used as a starting material and is converted to monomers through glycolysis in situ. (<NUM>) Bisphenol-A-fumarates: these are based on ethoxylated bisphenol-A and fumaric acid. (<NUM>) Vinyl ester resins: these are resins having unsaturated sites only in the terminal position. For example, such unsaturation may be introduced by reaction of epoxy resins (e.g., diglycidyl ether of bisphenol-A, epoxies of the phenol-novolac type, or epoxies based on tetrabromobisphenol-A) with (meth)acrylic acid. (<NUM>) Fumarate resins: these are resins derived from maleic acid, maleic anhydride, dimethyl maleate, fumaric acid, dimethyl fumarate, or diethyl fumarate, and glycols. (<NUM>) Maleate resins: these are resins derived from maleic acid, maleic anhydride, dimethyl maleate, or diethyl maleate, and glycols. (<NUM>) Itaconate resins: these are resins derived from itaconic acid, itaconic anhydride, dimethyl itaconate, or diethyl itaconate, and glycols.

The term "azo-type initiator" refers to a thermal free radical initiator having the general formula R-N=N-R', wherein R and R' are generally alkyl, or cycloalkyl groups, optionally possessing other functional groups. In certain embodiments, R and R' are selected from groups such as cyclohexyl; <NUM>-cyclohexyl-<NUM>-cyano; and C<NUM>-C<NUM> alkyl groups, optionally substituted by cyano, amido, or alkanoyl groups. Examples include products having the designations V-<NUM>, V-<NUM>, AIBN (azobisisobutyronitrile), V-<NUM>, V-<NUM>, V-<NUM>, and VAm-<NUM>, available from WAKO Chemicals USA, Inc. , including such compounds as:.

Further examples include those available from Chemours under the VAZO® mark, including VAZO® <NUM>, VAZO® <NUM>, VAZO® <NUM>, and VAZO® <NUM>, which correspond to <NUM>-<NUM>'-azobis(<NUM>,<NUM>-dimethylvaleronitrile); azobisisobutyronitrile; <NUM>,<NUM>'-azobis(<NUM>-methylbutanenitrile); and <NUM>,<NUM>'-azobis(cyclohexanecarbonitrile); respectively.

In certain embodiments, the azo-type initiators exhibit a selfaccelerating decomposition temperature between about <NUM>° to about <NUM>.

In certain embodiments, azo-type initiator is present in an amount of about <NUM> to about <NUM> weight percent, about <NUM> to about <NUM> weight percent, or about <NUM> to about <NUM> weight percent.

The "flow-enhancing agent" in one embodiment is a long chain metal salt of a fatty acid. Examples include zinc, calcium, and magnesium salts of C<NUM>-C<NUM> fatty acids, zinc stearate, magnesium stearate, calcium stearate, aluminum stearate, and the like. Additionally, the flow-enhancing agent may be a fumed silica such as those sold under various product designations under the Aerosil® mark, marketed by Evonik. The flow-enhancing agent is generally blended with the resin component (<NUM>) and the azo-type initiator (<NUM>) and ground into a free flowing powder of varying particle size.

As used herein, the term "continuous filament mat" (CFM) will be understood to mean a fiberglass mat created by looping one or various continuous fiberglass strands to produce a random fiber orientation. (See, for example, <CIT>. ) The fiberglass may be of any known composition and category such as those known as "E-glass", "A-glass", "C-glass", "D-glass", "R-glass", "S-glass", and E-glass derivatives. In one embodiment, the CFM mat is comprised of E-glass.

We have discovered that the compositions of the invention are capable of binding the various fiberglass strands that make a continuous fiberglass mat, providing the necessary mechanical and aesthetic properties required in consumer applications. The compositions provided herein meet the criteria that fiberglass manufactures require to make appropriate fiberglass mats which exhibit improved whiteness retention over time as compared to existing peroxy-initiated composite structures.

The compositions of the invention are useful, for example, as a binder in a variety of applications such as in the manufacture of glass fiber composites including roofing shingles, insulation, and the manufacture of mats or blankets which can then be formed into a desired shape and cured to provide a rigid three-dimensional structure. See, for example, <CIT> and <CIT>.

This invention can be further illustrated by the following examples of certain embodiments thereof, although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention.

Example #<NUM>. An ethylene glycol fumarate was cooked until an acid value of <NUM> was achieved. <NUM> parts of this polyester alkyd were pulverized and mixed intrinsically with <NUM> parts of Azobisisobutyronitrile [VAZO® <NUM>, AIBN] and <NUM> parts of Zinc stearate to produce Example #<NUM>.

Example #<NUM>. Following the procedure above, <NUM> parts of pulverized polyester alkyd, <NUM> parts of <NUM>,<NUM>'-Azodi(<NUM>-methylbutyronitrile) [VAZO® <NUM>, AMBN] and <NUM> parts of Zinc stearate were intrinsically mixed to produced Example #<NUM>.

Example #<NUM>. Following the procedure above, <NUM> parts of pulverized polyester alkyd, <NUM> parts of (<NUM>,<NUM>'-Azobis(cyanocyclohexane)) [VAZO® <NUM>, ACHN] and <NUM> parts of Zinc stearate were intrinsically mixed to produced Example #<NUM>.

All the compositions above were mixed by placing the various materials in an epoxy lined container. This container was then placed on a rock tumbler for <NUM> hour. After, <NUM>% water slurries were made out of each composition. Pieces of Uniconform mat (~ <NUM><NUM> (~<NUM> ft<NUM>)) were then soaked using the slurries. The soaked mats were allowed to air dry for <NUM> minutes and finally they were cured on a convection oven at <NUM> for a period of <NUM> minutes. The tensile strength of each cured mat was then determined.

The tensile strength results compiled from the Uniconform cured mats are summarized on Table #<NUM> (vide supra). The Uniconform mats cured using examples <NUM> and <NUM> show about half the tensile strength compared to the E240-8T control. Example <NUM>, which contains ACHN initiator, was capable of achieving close to <NUM>% of the tensile strength shown by the control. These compositions show promise as a possible replacement to benzoyl peroxide compositions. The differences observed between examples <NUM>-<NUM> could be attributed to several factors: lower radical generating efficiency of azo initiators compared to dibenzoyl peroxide or benzoperoxide (BPO), higher water solubility of azo initiators compared to BPO and, the complexity of the method utilized to make cured mats with these compositions.

Claim 1:
A composition for binding fibers to form a continuous filament fiberglass mat, the composition comprising:
(i) an unsaturated polyester or vinyl ester resin;
(ii) an azo-type initiator; and
(iii) a flow enhancing agent;
wherein the unsaturated polyester or vinyl ester resin is present in an amount of about <NUM> weight percent to about <NUM> weight percent, the total of (i), (ii), and (iii) being <NUM> weight percent.