Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-02-01
2001-04-03
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S106000, C521S120000, C521S121000, C521S124000, C521S130000, C521S131000, C521S137000, C528S076000, C528S079000, C528S085000, C525S131000, C524S711000, C524S745000, C524S748000, C524S758000
Reexamination Certificate
active
06211259
ABSTRACT:
BACKGROUND OF THE INVENTION
Thermosetting resin reinforcement technology as practiced today for the open-mold fabrication of hot tubs, bathtubs, recreational vehicle components, marine craft and components, etc. is fundamentally unchanged from that of forty years ago. Resin reinforcement is applied to the surface or cosmetic layer, in order to provide essential mechanical properties such as tensile strength, flexural strength, impact strength, and toughness. Thermosetting materials that can function as the reinforcing substrate include unsaturated polyesters, epoxies, polyurethanes, phenolics, vinyl esters, polyureas, polyisocyanurates, and the like, and/or combinations of the aforementioned materials. Combinations of two or more thermosetting chemistries are commonly referred to as interpenetrating networks or hybrid resin systems, the two types being differentiated by the type of reaction chemistry that takes place. Despite improvements in unsaturated polyester resin technology and the advent of hybrid resins, these types of systems have not progressed into an optimal rigidizing technology due to their fundamental dependence on a reactive diluent, such as styrene monomer. Isocyanate-based systems that do not require the use of a reactive diluent have been introduced in an attempt to overcome the drawbacks of conventional rigidizing systems. Unfortunately, these systems have not been able to fulfill the requirements of a rigidizing system in the majority of applications. In some applications, isocyanate-based systems can be used in conjunction with a thermoplastic surface layer of substantial thickness to produce a product with sufficient mechanical properties. However, this approach is not ideal and/or not appropriate for most applications. Consequently, the preponderance of applications requiring rigidizing such as those previously referenced and other applications associated with open-molding, rely almost exclusively upon the use of unsaturated polyester or hybrid resin technology.
In the majority of the prior art applications the surface or cosmetic layer of choice is a clear or pigmented gel coat that is also based on unsaturated polyester resin technology that incorporates the previously noted reactive diluent(s). In some applications the cosmetic layer is formulated as a gel coat using polyurethane technology. However, this technology has yet to find wide spread acceptance owing to its significantly higher cost. Other thermosetting resins that could be incorporated to provide the cosmetic surface include vinyl esters, alkyds, polyurethanes, polyureas, polyimides, epoxy resins, phenolics, amino resins, and allyl resins. In the remainder of the open-molding applications the substrate is a thermoformed thermoplastic polymer that has been incorporated into the component design to overcome some of the inherent deficiencies of the gel coat while additionally providing a high-gloss surface and acceptable appearance. Thermoplastic polymers are those resins that can be processed thermally to produce useful items and include but are not restricted to, polymethylmethacrylate polymers, polyvinyl halides, olefin polymers, styrenic polymers, polyesters, nylons, polysulfones, polycarbonates, polyacetals and the like. Composites, blends, and alloys of the aforementioned thermoplastic resins may also be used as the cosmetic layer. Examples include but are not restricted to polycarbonate/polymethylmethacrylate, polycarbonate/acrylonitrile-butadiene-styrene terpolymers, polycarbonate/polybutylene terephthalate, polystyrene/polyphenylene oxide, acrylonitrile-butadiene-styrene/polybutylene terephthalate, polyurethane/acrylonitrile-butadiene-styrene terpolymers, and the like. It is in conjunction with thermoplastic polymers that most of the hybrid resin-based systems or isocyanate-based systems are utilized as previously noted.
The unsaturated polyesters used in rigidizing systems are typically, but not exclusively, condensation polymers prepared from unsaturated di- or polycarboxylic acid(s) or anhydrides(s) with an excess of glycols and/or polyhydric alcohol(s) that result in a polyester polyol having at least one ethylenically unsaturated group per molecule having predominantly hydroxyl-terminated end groups. Typically the diacids of choice are maleic acid (anhydride), orthophthalic acid (phthalic anhydride) or isophthalic acid, or a combination thereof, with the glycol component being ethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, or a combination thereof. The resultant polyester polyol in turn is dissolved in an ethylenically unsaturated monomer solution at a level of 30-90 wt. %. Most often the monomer solution of choice is styrene. In addition, unsaturated polyesters can result from the synthesis of an addition polymer that is further modified by incorporation into a condensation polymer. This process typically incorporates maleic acid and dicyclopentadiene to create a diene-terminated ester. The resultant ester is then reacted with one or more of the aforementioned diol(s) that in turn is dissolved in an ethylenically unsaturated monomer solution. Optionally, fillers, fibers, catalysts, promoters, pigments, flame retardants, processing aids such as thixotropic agents and internal lubricants or surfactants, all of which are well known to those skilled in the art, can be added or employed to gain the desired reaction rate(s) and physical properties. The unsaturated polyesters used as gel coats are typically, but not exclusively, based on the same technology as described above while having a lower initial viscosity to facilitate the addition of pigment at various loadings. In order to achieve the desired high-gloss and surface appearance associated with gel coats they are formulated to have a very hard and therefore, brittle surface.
Hybrid systems are typically saturated or unsaturated polyester-polyurethane resins that are well known in the art of thermoset compositions. These resins are normally tougher than unsaturated polyesters and stronger, stiffer and less expensive than polyurethane. Such resins generically comprise a hydroxyl-terminated unsaturated polyester polyol, an ethylenically unsaturated monomer, and a multifunctional isocyanate. Typically, these resins are provided as a two or more component system. Common terminology in the art is to refer to these as an “A-Side” component, containing the multifunctional isocyanate and usually one or more free radical initiators, and a “B-Side” component usually containing the hydroxyl-terminated polyester polyol and ethylenically unsaturated monomer, as well as a polyurethane catalyst, a peroxide promoter, chain extender and optionally water. Examples of typical prior art hybrid systems are set forth in U.S. Pat. Nos. 5,153,261; 5,296,544; 5,296,545; 5,302,634; 5,344,852; 5,447,921; 5,464,919 and 5,482,648. These and other patents cited herein are incorporated by reference.
Various isocyanate-based systems can provide reinforcement to thermoformed thermoplastic components as cited in U.S. Pat. Nos. 4,738,989; 4,748,192; 4,748,201; 4,844,944; 5,380,768 and 5,420,169. The referenced systems can be closed-cell foams, open-cell foams or of the non-foaming type. Typically, but not exclusively, the type of polyol that is incorporated to form the polyurethane network can differentiate these foams. Incorporating typical polyether and/or polyester polyols can produce other rigid foam systems having good properties when multifunctional polyols and/or highly rigid polyols are preferentially used. Examples of prior art in this field can be found in U.S. Pat. Nos. 4,581,388; 5,284,882; 5,496,496 and 5,770,635. The aforementioned hybrid systems in comparison use an unsaturated polyester polyol or an acrylate containing hydroxyl compound to form a crosslinked urethane backbone offering very good properties when combined with a reactive monomer such as styrene monomer or methyl methacrylate monomer. An important consideration must also include the discussion of foam density since it is known that low-density rigid foams ha
Anderson, Jr. Robert E.
Borden Keith A.
Reynolds Randall S.
Yusko Kathleen M.
Aristech Acrylics LLC
Gorr Rachel
Thorp Reed & Armstrong LLP
LandOfFree
Low volatile reinforcing system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Low volatile reinforcing system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Low volatile reinforcing system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2511341