Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Bulk deposition of particles by differential fluid pressure
Reexamination Certificate
1999-03-17
2001-06-26
Dixon, Merrick (Department: 1774)
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Bulk deposition of particles by differential fluid pressure
C264S907000, C264S909000, C427S294000, C427S436000, C427S124000
Reexamination Certificate
active
06251334
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to composite structures in which an inorganic layer is joined to an organic layer.
2. Description of the Related Art
The fabrication of multilayer materials can pose manufacturing challenges, and the resulting constructions may exhibit performance limitations, where different types materials are joined at an interface. This is particularly so in the case of constructions having an inorganic material, such as a metal or metal compound, joined to an organic (e.g., polymeric) material. The abrupt transition between layers having very different physical properties, such as stiffness and rates of heat transport, and chemical compositions can compromise their anchorage to one another—a critical performance requirement in many applications—as well as the durability of the inorganic layer. For example, because inorganic and organic materials typically have very different coefficients of thermal expansion and elastic moduli, even perfectly adhered inorganic layers may undergo failure (e.g., fracturing) due to temperature variations or stress during manipulation and ultimate use. The different responses of two adjacent layers to an external condition can easily cause damage that would not occur in either layer by itself.
To improve interlayer anchorage, polymeric layers may be selected (or applied as intermediate coatings) based on chemical compatibility with inorganic material. A polymeric layer may also be pretreated (e.g., through plasma exposure) to modify the surface for greater interfacial compatibility with a subsequently applied inorganic layer. These approaches, however, have limited utility in addressing the effects of transition between fundamentally different materials.
DESCRIPTION OF THE INVENTION
Brief Summary of the Invention
The present invention reduces the abruptness of interfacial transition by altering the effective properties of the organic layer (to which the inorganic layer is applied) by incorporating an inorganic component within the matrix of the organic layer. Accordingly, in a first aspect, the invention comprises a method of fabricating a multilayer construction having adjacent organic and inorganic layers. A first layer comprising a curable polymer is softened, and an inorganic material—compatible with or compositionally identical to—the soon-to-be-applied inorganic layer is deposited onto a surface of the softened polymer. The inorganic material overspreads the surface and integrates within the soft polymeric layer; at this point, it may be desirable to assist the migration of the inorganic material into the polymer (e.g., by charging the inorganic material and applying an opposite charge to a conductor underlying the polymer). The polymer is then cured to immobilize the integrated deposition material, thereby forming a composite, and the desired inorganic layer is applied over the deposited inorganic material (and any exposed portions of the polymer). Depending on the application, the deposition material may fully cover the surface of the polymeric material, forming a continuous layer thereover, or may instead form an intermittent pattern over the surface.
The polymer is generally chosen both for its suitability to a desired application and for its ability to be cured into a rigid, three-dimensional structure that permanently immobilizes the inorganic deposition material. That material and its degree of loading into the polymer may be chosen to confer desired physical and/or chemical characteristics to the composite material; that is, while the composite layer may exhibit “inorganic” characteristics essential to interlayer compatibility, it may nonetheless retain various “organic” characteristics important to a particular application. For example, while the inorganic phase may have a pronounced effect on the stiffness and heat-transport properties of the composite, thereby enhancing physical compatibility with a pure inorganic layer, it may not significantly affect surface energy (so that the composite retains the the affinity for ink and/or an ink-abhesive fluid that characterized the original polymer).
The resulting multilayer material is ordinarily permanent, resisting degradation due to handling or environmental conditions. Accordingly, not suitable for the present invention are polymeric materials that exhibit a low glass-transition temperature (which permits repeated, temperature-dependent transitions between soft and rigid states) unless provided with crosslinking groups that facilitate permanent cure (and thereby defeat further phase transitions). In a preferred embodiment, the polymer comprises an acrylic polymer combined with a multifunctional acrylate monomer, which are crosslinked following deposition of the inorganic material. Acrylates, like many inorganic deposition materials, can be deposited under vacuum, permitting the entire fabrication process to be carried out in a single operation.
The multilayer constructions obtainable in accordance with the present invention are suitable to a wide variety of uses ranging from packaging to decorative materials to optical and electronic devices—essentially wherever organic and inorganic layers must be joined. For example, optically variable devices (such as the thin-film devices described in U.S. Pat. No. 4,705,356) may utilize a stack of thin layers to provide a desired optical effect (e.g., behavior as an interference filter). These layers may comprise, for example, a bottommost metal reflective layer, above which are disposed various dielectric and other metal layers. In accordance with the invention, the bottommost layer is joined to a composite substrate so the optical structure remains firmly bonded thereto, resisting delamination that could occur as a result of poor or vulnerable adhesion. Optical devices of this type may serve as labels, artwork, color-shift materials, and information-bearing structures.
Similarly, the invention may be employed in connection with optical filters having desired radiation-transmission properties (e.g., solar-control films for windows that reflect ultraviolet (UV) radiation); optical-storage structures that include an inorganic storage layer; large-array solar collectors; and electrochromic materials. In addition, the invention may be used in conjunction with electrical components such as thin-film resistors and capacitors.
Beyond compatibility, the deposition material may also confer a desired physical property to the organic layer. For example, the deposition material may be magnetic (e.g., a rare-earth magnetic material). Indeed, in this case, the material may not even be brought into contact with an overlying inorganic layer; instead the substrate may be turned over and the magnetic material used to anchor the substrate to an appropriate surface by magnetic hold-down.
In a second aspect, a graded structure is built up on a substrate in successive deposition steps. Both polymer precursors and an inorganic filler material are deposited in stages, with each stage containing a desired ratio of polymer to filler. In a preferred embodiment, the proportion of filler increases in each stage, resulting in a concentration gradient with the amount of filler increasing away from the substrate. The polymer precursors may be cured after each stage of deposition, permanently immobilizing the distribution of organic and inorganic material. An inorganic top layer is applied over a surface of the structure. The top layer, but not the underlying graded structure, may be subject to ablative removal by exposure to laser radiation.
The polymer precursor and the filler material may be deposited as a vapor or as a liquid. In one embodiment, the precursor is an acrylic polymer combined with a multifunctional acrylate monomer, the curing step crosslinking the monomers with the polymer.
REFERENCES:
patent: 4482622 (1984-11-01), Soden et al.
patent: 4490774 (1984-12-01), Olson et al.
patent: 4647818 (1987-03-01), Ham
patent: 4696719 (1987-09-01), Bischoff
patent: 4842893 (1989-06-01), Yializis et al
Dixon Merrick
Presstek Inc.
Testa Hurwitz & Thibeault LLP
LandOfFree
Composite constructions having mixed organic/inorganic layers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Composite constructions having mixed organic/inorganic layers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composite constructions having mixed organic/inorganic layers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2509119