Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
1999-05-27
2001-07-17
Yoon, Tae H. (Department: 1714)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
C525S330700, C524S430000, C524S431000, C524S492000, C524S497000, C524S551000
Reexamination Certificate
active
06261700
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to abrasion or scratch resistant protective coatings, composite structures containing such coatings, and compositions for preparing and methods of preparing such coatings and composite structures.
BACKGROUND
Many important commercial products, including optically functional products such as lenses, light fibers, optical screens and filters, reflective sheeting, and the like, have structures or are prepared from materials that are susceptible to physical damage. Alternatively, there may exist some other reason why such products benefit from protection against physical or mechanical damage. To protect these products, a tough, abrasion resistant “hardcoat” layer may be coated and cured onto their structures.
Abrasion resistant hardcoats can include a polymeric binder matrix formed from a curable material, and inorganic oxide materials suspended or dispersed within the polymeric binder. See, e.g., WO 96/36669 A1, which describes a hardcoat formed from a “ceramer” used, in one application, to protect the surfaces of retroreflective sheeting from abrasion. As is known in the art of ceramer compositions, ceramers can be derived from aqueous sols of inorganic colloids according to a process in which a curable binder precursor and other optional ingredients are blended into the aqueous sol. The resulting curable composition is dried to remove substantially all of the water. Solvent may then be added, if desired, in amounts effective to provide the composition with viscosity characteristics suitable for coating the composition onto a desired substrate. After coating, the composition can be dried to remove the solvent, and then exposed to a suitable source of energy to cure the binder precursor.
Optically functional products can include coatings having the primary function of enhancing or reducing light reflectance from the surface of a substrate. When such a coating reduces the amount of light reflected by the substrate, it is called “antireflective.” When the coating enhances the amount of light reflected by the substrate it is called “reflective.”
Antireflective (AR) coatings in particular are becoming increasingly important in commercial applications. The transparency of plastic or glass, in the form of doors, windows, lenses, filters, display devices (e.g., display panels) of electronic equipment, and the like, can be impaired by glare or reflection of light. To reduce the amount of glare on plastic or glass, the surface can include a layer of a metal oxide (such as silicon dioxide or indium tin oxide (ITO)), or suitably alternating layers of metal oxides, such as ITO/SiO
2
. For example, glass surfaces can typically have about 4% surface reflection, but with the aid of specialized coatings, such as multilayers of sputter deposited ITO/SiO
2
, surface reflection can be reduced to less than about 0.5% in the visible region of the spectrum (400-700 nm).
Importantly, the reflectivity or antireflectivity of a multi-layer optically functional composite article depends not only on the reflectivity of each layer, but also on the relative refractive indices of layers that are adjacent within the composite structure. Adjacent layers having similar or identical refractive indices will cause little or no additional reflection. But, if the indices of refraction of adjacent layers of a multilayer optically functional composite are different, this will cause reflectance of light at the interface of such adjacent layers, and diminish antireflective properties.
There is a need for chemical compositions that can function as abrasion-resistant “hardcoat” compositions. There exists an even more specific need for such hardcoats having optical properties (e.g., specific indices of refraction) wherein the hardcoat composition can be useful in optical product applications, for example in optically functional composites having reflective or antireflective properties.
SUMMARY OF THE INVENTION
In brief summary, the invention provides ceramer compositions, ceramer solutions, hardcoat compositions, and optically functional composite structures including the hardcoat compositions. The ceramer compositions contain ingredients including inorganic oxide particles and a curable binder precursor, wherein the binder precursor includes a polymerizable brominated compound. The polymerizable brominated compound can contain a brominated monomer having a relatively high index of refraction, e.g., at least about 1.5, and/or can contain at least one aromatic, brominated (meth)acrylate compound. The ceramer composition can be cured or polymerized to form a hardcoat composition including a brominated polymeric matrix having dispersed therein, or surrounding the inorganic oxide particles. The ceramer and hardcoat compositions can have desirable physical (e.g., mechanical) and optical properties such as hardness, scratch and abrasion resistance, and index of refraction. A desired index of refraction may be one that is sufficiently high (e.g., maximized), or one that is appropriately chosen to match an adjacent layer of a multilayer composite, e.g., to match a substrate to which the ceramer composition is coated.
An aspect of the invention relates to a chemical composition including inorganic oxide particles and an aromatic, brominated (meth)acrylate compound. The binder precursor may further contain polymerizable non-brominated compounds, and may further comprise a coupling agent, an organic or aqueous solvent, or both.
A further aspect of the invention relates to a chemical composition containing inorganic oxide particles and a polymerizable brominated compound, wherein the polymerizable brominated compound exhibits an index of refraction of at least about 1.5.
Yet a further aspect of the invention relates to a cured hardcoat composition including a brominated polymer and inorganic oxide particles, wherein the polymer includes monomeric units derived from a polymerizable composition including a polymerizable brominated compound having an index of refraction of at least about 1.5.
Yet a further aspect of the invention relates to a cured hardcoat composition including a brominated polymer and inorganic oxide particles, wherein the polymer includes monomeric units derived from a polymerizable composition including a polymerizable, aromatic, brominated (meth)acrylate compound.
Yet a further aspect of the invention relates to a composite structure including a substrate and a hardcoat composition, wherein the hardcoat includes inorganic oxide particles and a brominated polymer. The brominated polymer comprises monomeric units derived from a polymerizable composition comprising brominated monomers such as a brominated compound having an index of refraction of at least about 1.5, and/or a polymerizable, aromatic (meth)acrylate compound. The composite structure can include other layers or components including a primer layer, an antireflective layer, or one or more other optically functional layers. These composite structures can be used as optical products such as antireflective composite structures.
As used within the present description, the following terms shall have the given meanings.
“Ceramer composition” or “ceramer” refers to any mixture comprising substantially non-aggregated, colloidal or suspended inorganic oxide particles dispersed in a curable binder precursor. The ceramer composition can optionally contain a coupling agent, and can optionally contain organic or aqueous solvent. A ceramer composition diluted with solvent, e.g., to facilitate processing and coating onto a substrate, can be referred to as a “ceramer solution.”
“Curable” refers to a material that can be thickened or solidified e.g., by heating to remove solvent, heating to cause polymerization, chemical crosslinking, radiation polymerization or crosslinking, or the like.
“Cured” means a curable material that has been so thickened or solidified.
“Polymerizable” refers to chemical compounds such as monomers, dimers, trimers, oligomers, pre-polymers, or polymers etc., and chemical compositions, capable of undergoing
Arney David S.
Bilkadi Zayn
Fong Bettie C.
Kang Soonkun
Olson David B.
Yoon Tae H.
Zillig Kimberly S.
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