Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1998-02-27
2001-04-17
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C264S240000, C264S255000, C264S257000
Reexamination Certificate
active
06218458
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to gas occlusion-free and void-free, two-primary phase, solidifiable compounds, and derived void-free solidified composite materials, and more particularly to gas occlusion-free and void-free polymeric solidifiable compounds and derived void-free solidified composites, including methods and apparatus for producing same.
2. Description of Related Art
a. Terminology
Because certain terms in the field of the invention may be used in different ways to signify the same or slightly differing concepts, the following definitions are provided to promote clarity for the following description of the invention.
The term “primary solid phase” is defined herein as one or more distinct solid substances each physically homogeneous, in solid state, which serves primarily as material reinforcement upon solidification of the primary liquid phase.
The term “primary solidifiable liquid phase” is defined herein as one or more distinct liquid substances, each physically homogeneous, in liquid state, capable of solidifying to constitute a solid continuous material matrix that binds the primary solid phase at ambient temperatures.
The term “compound” is defined as the unsolidified state of a composite.
The term “composite” is defined here as any solid primary phase mixed with any primary solidifiable liquid phase, forming a monolithic two-phase solid state material upon solidification of the liquid primary phase.
When the two primary phases are mixed to yield a compound, these primary phases are no longer in their primary state but in an unsolidified, multiphase, “mixed state” as defined herein.
The term “voids” are defined herein as filled or unfilled spaces, within interstices of a packed primary solid phase or surface pores in solid constituents. Voids are further defined as gas phase occlusions within a primary liquid phase originating from entrainment and/or adsorption of air, water vapor and other gases within the interstices of the solids in the primary solid phase, within the primary solidifiable liquid phase or within the multiphase, mixed unsolidified state of the two phases. The term “voids”, as defined above, specifically excludes intermolecular and atomic spaces, which are natural unfilled spaces in matter. Furthermore, the scale of physical measurement of voids herein is about one micron (10
−6
m) or more.
b. Polymeric Compounds and Composites
An extremely wide range of products are being manufactured today from a specific class of two primary phase compounds in which the primary solidifiable liquid phase is a polymeric resin. The process leading to the production of a polymeric composite involves mixing a generic primary solid phase with a polymeric resin system, thereby constituting a two-phase unsolidified compound. Upon further processing, the polymeric resin in the mixed unsolidified state is made to solidify, or harden, in an appropriate forming device, such as a mold or a die, yielding a formed, solid composite with the shape, or configuration, of the forming device.
The role of the polymeric liquid resin system in polymeric composites is to provide an essential binding matrix to the primary solid phase upon solidification. Initially, its low viscosity provides an adequate liquid medium for mixing with the solids of the primary solid phase. Upon solidification, the resin matrix provides a continuous solid phase that enables the composite to behave monolithically as a single solid material body.
Resin systems in polymeric composites are further classified as either thermoplastic, which soften when heated and may be shaped or reshaped while in a semifluid state or thermosetting, which are generally low viscosity liquids that solidify through chemical cross-linking. The most common resin systems in polymeric composites are thermosetting, and the most predominant thermosetting resin is unsaturated polyester. Other thermosetting resins include epoxies, vinylesters, phenolics and urethanes.
Certain thermosetting polymer resin systems consist of solid polymer particles dissolved in a low viscosity liquid and solvent monomer, for example, an unsaturated polyester dissolved in monostyrene. The monomer plays the dual role of providing a solvent medium for the distribution of the polymer resin, and also has the ability to react with the polymer into a final solid state. Such thermosetting resin systems are made to harden or solidify into a permanent shape by an irreversible chemical reaction known as curing or cross-linking, in which linear polymer chains and monomer chains in the liquid resin system are joined, or reacted, together to form complex, highly rigid, three-dimensional solid structures. This reaction requires anaerobic conditions; i.e., the liquid resin system will not harden in the presence of air. Thus the presence of O
2
is known to have an inhibitory effect on the polymerization/solidification process. Additionally, water, which is known to diffuse into liquid thermosetting resin systems, significantly impairs the cross linking solidification reaction.
An additional property of thermosets is that they are generally brittle. Thus, thermosets are rarely used without some form of solid reinforcement. However, high resistance to weight ratio, ability to solidify at ambient temperatures and retain their shape and properties at somewhat elevated temperature as, well as good creep resistance and corrosion resistance properties, give thermoset resin systems significant advantages over thermoplastics. These advantages essentially are the reasons for their preference in the developmental history of polymeric composites.
The role played by the solids in the primary solid phase matrix of polymeric composites is one of structural reinforcement. Moreover, the choice of geometrical shape of the solid phase constituents is a function of the intended reinforcement requirement of the particular polymeric composite in terms of the type of predominant stresses from externally applied forces that are to be resisted. The geometrical shape of the solid reinforcement generally can be of two generic classes: 1) filament shaped, or fiber and 2) granular/spherical shaped, or aggregate-type solid material. The fiber reinforced polymeric composites are intended for predominantly tensional, mechanical resistance applications, whereas the aggregate reinforced polymeric composites are intended for predominantly compressional, mechanical resistance applications. These generic classes of solids can be viewed as forming two ends of the structural resistance spectrum of polymeric composites.
Polymer composites composed of fibrous solid materials mixed with thermosetting polymeric resin are known as “Fiber Reinforced Polymers” or FRPs. The most common fibers used in the present art are glass, graphite, ceramic and polymeric fibers. Depending on the particular production process used, this generic class includes polymeric composite materials such as “Glass Reinforced Plastics” (GRP), produced by open, manual or spray, lay up methods, pultrusion, filament winding, etc. or by enclosed methods such as “Resin Transfer Molding” (RTM), Seeman Composites Resin Infusion Manufacturing Process (SCRIMP), etc. Other FRP composites produced by enclosed methods are based on polymeric compound materials, such as “Bulk Molding Compound” (BMC), “Sheet Molding Compound” (SMC), “Thick Molding Compound” (TMC), etc. In the mixed solidifiable compound state, the latter fiber reinforced polymeric materials, appropriately handled, can be stored for extended periods of time for future forming and curing at appropriate combinations of pressure and temperature into final solid composite products.
Solid aggregate materials mixed with thermosetting polymeric resin (resins) matrices comprise the generic class of polymeric composites known as cast polymer products, polymer concretes, polymer mortars or polymer grouts. To date, the inorganic aggregates for polymeric composites have not been systematically characterized, but most common aggregates used i
Bendek Wilfredo G.
Dufeu Jorge L.
Vidaurre Victor H.
Choi Ling-Siu
Mardela International Inc. S.A.
Rader & Fishman & Grauer, PLLC
Wu David W.
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