Optical: systems and elements – Light interference – Produced by coating or lamina
Reexamination Certificate
1999-08-10
2002-01-01
Spyrou, Cassandra (Department: 2872)
Optical: systems and elements
Light interference
Produced by coating or lamina
C359S580000, C359S599000
Reexamination Certificate
active
06335832
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a transparent functional membrane wherein functional ultrafine particles having various functions, such as a UV screening effect, an antistatic effect, and an antireflection effect, are localized in a coating, particularly localized and fixed in a coating on its surface layer in contact with or near air, thereby enabling the functions of the functional ultrafine particles to be developed, a transparent functional film, and a process for producing the same. Further, the present invention relates to an antireflection film comprising the above transparent functional film having an antireflection effect, and a process for producing the same.
It is known that a transparent functional film having functions, such as a UV screening property, an antistatic property, or an antireflection property, can be produced by coating on a transparent plastic substrate film a transparent resin composition with functional ultrafine particles having particular properties, such as a UV screening effect, an antistatic effect, and an antireflection effect, being dispersed therein, thereby forming a functional coating.
Further, it is also known that, in order to impart additional properties, such as scratch resistance and chemical resistance, to the above transparent functional film, a transparent functional film having a hard property can be produced by forming as an intermediate layer a hard coat layer of, for example, an ionizing radiation curing resin on a transparent plastic substrate film and coating thereon a transparent resin composition with functional ultrafine particles being dispersed therein.
In the transparent functional film containing the above functional ultrafine particles, the functional ultrafine particles are present in a dispersed form in a transparent functional membrane due to the nature of the process. The incorporation of a larger amount of functional ultrafine particles in the membrane can further enhance the function of the functional ultrafine particles. In this case, however, the filling ratio of the functional ultrafine particles dispersed in the resin should be increased, making it difficult to form a film. Further, the transparent functional film having a hard coat layer of an ionizing radiation curing resin or the like has a problem that the adhesion between the hard coat layer and the transparent functional membrane is so low that the transparent functional membrane is likely to peel off.
DISCLOSURE OF THE INVENTION
The present invention can be divided into three groups A, B, and C which will now be described one by one.
Invention Belonging to Group A
An object of the present invention belonging to group A is to provide a transparent functional membrane, wherein functional ultrafine particles are localized in a high density as a functional ultrafine particle layer in a hard coat layer, thereby enabling the functions of the functional ultrafine particles to be developed and, at the same time, the hard coat layer and the functional ultrafine particles to have excellent adhesion to each other, a transparent functional film, an antireflection film, and process for producing the same.
Another object of the present invention is to provide an antireflection film comprising a transparent functional film having an antireflection effect and a process for producing the same.
The first transparent functional membrane of the present invention comprises a hard coat layer and functional ultrafine particles localized in and fixed to said hard coat layer on the side of at least one surface thereof in contact with an external atmosphere.
The second transparent functional membrane comprises a hard coat layer and functional ultrafine particles localized in and fixed to said hard coat layer on the side of at least one surface thereof in contact with an external atmosphere, a thin film of said hard coat layer being absent in the functional ultrafine particles in their portions in contact with an air layer (an external atmosphere) to cause part of the functional ultrafine particles to be exposed particularly on the hard coat layer.
The transparent functional films of the present invention respectively comprise the first and second transparent functional membranes each formed on a transparent plastic substrate film.
The first process for producing the first and second transparent functional films comprises the steps of: (1) forming a layer of functional ultrafine particles on a release film; (2) coating on a transparent plastic substrate film a resin composition for a hard coat layer; (3) laminating, by press-bonding, the coated transparent plastic substrate film prepared in said step (2), as such, when said resin composition for a hard coat layer contains no solvent, or after removing a solvent when said resin composition for a hard coat layer contains a solvent as a diluent, to the coated release film prepared in said step (1) so that the layer of functional ultrafine particles on the release film faces the resin composition coating for a hard coat layer on said transparent plastic substrate film, thereby causing said layer of functional ultrafine particles to be entirely or partly embedded in said resin composition coating for a hard coat layer; and (4) full curing said laminate prepared in said step (3) and peeling off said release film to transfer said layer of functional ultrafine particles to said transparent plastic substrate film.
Further, the present invention include other embodiment of the above production process, which will be described in detail later.
Invention Belonging to Group B
The present invention belonging to group B relates to an antireflection sheet having the effect of preventing reflection at various displays of word processors, computers, and television, surfaces of polarizing plates used in liquid crystal displays, optical lenses, such as sun glass lenses of transparent plastics, lenses of eyeglasses, finder lenses for cameras, covers for various instruments, and surfaces of window glasses of automobiles and electric railcars.
Transparent substrates, such as glasses and plastics, are used in curve mirrors, back mirrors, goggles, window glasses, displays of personal computers and word processors, and other various commercial displays. When visual information, such as objects, letters, and figure, is observed through these transparent substrates or, in the case of mirrors, when an image from a reflecting layer is observed through the transparent substrates, light reflects at the surface of the transparent substrates, making it difficult to see the visual information through the transparent substrates.
Conventional methods for antireflection of light include, for example, a method wherein an antireflection coating is coated on the surface of glass or plastics, a method wherein a very thin film of MgF
2
or the like having a thickness of about 0.1 &mgr;m or a metal deposited film is provided on the surface of a transparent substrate, such as glass, a method wherein an ionizing radiation curing resin is coated on the surface of plastics, such as plastic lenses, and a film of SiO
2
or MgF
2
is formed thereon by vapor deposition, and a method wherein a coating having a low refractive index is formed on a cured film of an ionizing radiation curing resin.
It is already known that, when incident light perpendicularly enters a thin film, in order for the antireflection film to prevent the reflection of light by 100% and to pass light by 100% therethrough, relationships represented by the equations (1) and (2) should be met (see “Science Library” Physics=9 “Optics,” pp.70-72, 1980, Science Sha Ltd., Japan).
n
0
={square root over (n
g
+L )} equation (1)
n
0
h=&lgr;
0
/4 equation (2)
wherein &lgr;
0
represents a particular wavelength, n
0
represents the refractive index of the antireflection film at this wavelength, h represents the thickness of the antireflection film, and n
g
represents the refractive index of the substrate.
It is already known that the refractive in
Katagiri Hiroomi
Nakamura Norinaga
Oka Motohiro
Ota Yurie
Suzuki Hiroko
Dai Nippon Printing Co. Ltd.
Jr. John Juba
Parkhurst & Wendel LLP
Spyrou Cassandra
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