U.S. patent application number 11/019743 was filed with the patent office on 2005-07-14 for fine inorganic oxide dispersion, coating composition, optical film, antireflection film, polarizing plate, and image display device.
This patent application is currently assigned to FUJI PHOTO FILM CO., LTD.. Invention is credited to Yoneyama, Hiroyuki.
Application Number | 20050154086 11/019743 |
Document ID | / |
Family ID | 34742145 |
Filed Date | 2005-07-14 |
United States Patent
Application |
20050154086 |
Kind Code |
A1 |
Yoneyama, Hiroyuki |
July 14, 2005 |
Fine inorganic oxide dispersion, coating composition, optical film,
antireflection film, polarizing plate, and image display device
Abstract
An inorganic oxide dispersion containing an organic solvent, and
inorganic oxide particles surface-treated with at least one of a
hydrolyzate and a partial condensate of an organosilane compound
represented by formula (I), the inorganic oxide particles being
dispersed in the organic solvent: (R.sup.10).sub.m--Si(X).sub.4-m
(I) as defined herein, the surface treatment of the inorganic oxide
particles being carried out in a presence of at least one of: (a)
an acid catalyst; and (b) a metal chelate compound having Zr, Ti or
Al as a center metal and at least one of an alcohol represented by
formula: R.sup.3OH in which R.sup.3 represents an allyl group
having 1 to 10 carbon atoms, and a compound represented by formula:
R.sup.4COCH.sub.2COR.sup.5 as defined herein, as a ligand.
Inventors: |
Yoneyama, Hiroyuki;
(Minami-Ashigara-shi, JP) |
Correspondence
Address: |
BURNS DOANE SWECKER & MATHIS L L P
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
FUJI PHOTO FILM CO., LTD.
Minami-Ashigara-shi
JP
|
Family ID: |
34742145 |
Appl. No.: |
11/019743 |
Filed: |
December 23, 2004 |
Current U.S.
Class: |
523/213 |
Current CPC
Class: |
C09C 1/3081 20130101;
C09C 1/3661 20130101; C01P 2004/84 20130101; C09C 3/12 20130101;
C09C 1/3692 20130101; C09C 1/3684 20130101; C08K 9/06 20130101;
C09C 1/309 20130101; C09C 1/3054 20130101 |
Class at
Publication: |
523/213 |
International
Class: |
C08K 009/06 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 2003 |
JP |
2003-434144 |
Mar 25, 2004 |
JP |
2004-090450 |
Claims
What is claimed is:
1. An inorganic oxide dispersion containing an organic solvent, and
inorganic oxide particles surface-treated with at least one of a
hydrolyzate and a partial condensate of an organosilane compound
represented by formula (I), the inorganic oxide particles being
dispersed in the organic solvent:(R.sup.10).sub.m--Si(X).sub.4-m
(I)wherein R.sup.10 represents a substituted or unsubstituted alkyl
group or a substituted or unsubstituted aryl group; X represents a
hydroxyl group or a hydrolyzable group; and m represents an integer
of 1 to 3, the surface treatment of the inorganic oxide particles
being carried out in a presence of at least one of: (a) an acid
catalyst; and (b) a metal chelate compound having Zr, Ti or Al as a
center metal and at least one of an alcohol represented by formula:
R.sup.3OH in which R.sup.3 represents an alkyl group having 1 to 10
carbon atoms, and a compound represented by formula:
R.sup.4COCH.sub.2COR.sup.5 in which R.sup.4 represents an alkyl
group having 1 to 10 carbon atoms; and R.sup.5 represents an alkyl
group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10
carbon atoms, as a ligand.
2. A process for producing a dispersion of inorganic oxide
particles dispersed in an organic solvent, comprising the steps of:
(1) surface treating inorganic oxide particles with at least one of
a hydrolyzate and a partial condensate of an organosilane compound
represented by formula (I):(R.sup.10).sub.m--Si(X).sub.4-m
(I)wherein R.sup.10 represents a substituted or unsubstituted alkyl
group or a substituted or unsubstituted aryl group; X represents a
hydroxyl group or a hydrolyzable group; and m represents an integer
of 1 to 3, in an organic solvent having a small ketone solvent
content in a presence of at least one of (a) an acid catalyst and
(b) a metal chelate compound having Zr, Ti or Al as a center metal
and at least one of an alcohol represented by formula: R.sup.3OH in
which R.sup.3 represents an alkyl group having 1 to 10 carbon
atoms, and a compound represented by formula:
R.sup.4COCH.sub.2COR.sup.5 in which R.sup.4 represents an alkyl
group having 1 to 10 carbon atoms; and R.sup.5 represents an alkyl
group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10
carbon atoms, as a ligand, and (2) replacing the organic solvent
used for the surface treatment with an organic solvent having an
increased ketone solvent content.
3. An inorganic oxide dispersion obtained by the process according
to claim 2.
4. The inorganic oxide dispersion according to claim 1, wherein the
inorganic oxide particles are surface treated with the at least one
of a hydrolyzate and a partial condensate of the organosilane
compound represented by formula (I) and a compound having at least
one of a fluoroalkyl group and a fluorine-containing aromatic
group.
5. The inorganic oxide dispersion according to claim 4, wherein at
least one of the organosilane compound represented by formula (1)
and the compound having at least one of a fluoroalkyl group and a
fluorine-containing aromatic group is a fluorine-containing silane
coupling agent represented by formula
(1):(Rf--L.sub.1).sub.n--Si(R.sup.1- 1).sub.n-4 (1)wherein Rf
represents a straight-chain, branched or cyclic fluoroalkyl group
having 1 to 20 carbon atoms or a fluorine-containing aromatic group
having 6 to 14 carbon atoms; L.sub.1 represents a divalent linking
group having 10 or fewer carbon atoms; R.sup.11 represents a
hydroxyl group or a hydrolyzable group; and n represents an integer
of 1 to 3.
6. The inorganic oxide dispersion according to claim 5, wherein the
fluorine-containing silane coupling agent is represented by formula
(2):C.sub.nF.sub.2n+1--(CH.sub.2).sub.m--Si(R).sub.3 (2)wherein n
represents an integer of 1 to 10; m represents an integer 1 to 5;
and R represents an alkoxy group having 1 to 5 carbon atoms or a
halogen atom.
7. The inorganic oxide dispersion according to claim 1, wherein the
organosilane compound of formula (I) is represented by formula
(II): 46wherein R.sup.10 represents a substituted or unsubstituted
alkyl group or a substituted or unsubstituted aryl group, X
represents a hydroxyl group or a hydrolyzable group; R.sup.1
represents a hydrogen atom, a methyl group, a methoxy group, an
alkoxycarbonyl group, a cyano group, a fluorine atom or a chlorine
atom; Y represents a single bond, --COO--, --CONH-- or --O--; L
represents a divalent linking group; and n represents 0 or 1.
8. The inorganic oxide dispersion according to claim 1, wherein the
inorganic oxide particles are silica particles.
9. The inorganic oxide dispersion according to claim 1, wherein the
inorganic oxide particles are hollow silica particles.
10. A coating composition comprising the inorganic oxide dispersion
according to claim 1 and a film-forming composition comprising a
compound having an ethylenically unsaturated group.
11. The coating composition according to claim 10, wherein the
compound having an ethylenically unsaturated group is a main
component of the film forming composition.
12. An optical film comprising a transparent substrate and a layer
formed of the coating composition according to claim 10.
13. The optical film according to claim 12, wherein the inorganic
oxide particles in the coating composition are hollow particles,
and the layer has a refractive index of 1.20 to 1.46.
14. The optical film according to claim 12, wherein the inorganic
oxide particles in the coating composition are hollow silica
particles having a refractive index of 1.17 to 1.40.
15. An antireflection film comprising a transparent substrate and
an antireflection layer provided on the substrate, the
antireflection layer comprising a low refractive layer formed of
the coating composition according to claim 10.
16. The antireflection film according to claim 15, wherein the
inorganic oxide particles of the coating composition are hollow
silica particles an average particle size of which is 30% to 150%
of a thickness of the low refractive layer.
17. The antireflection film according to claim 15, wherein the
coating composition of the low refractive layer contains a
fluoropolymer represented by formula (A): 47wherein L represents a
linking group having 1 to 10 carbon atoms; m represents 0 or 1; X
represents a hydrogen atom or a methyl group; A represents a
repeating unit derived from at least one vinyl monomer; and x, y,
and z represent a mole percent of respective repeating units in
ranges 30.ltoreq.x.ltoreq.60, 5.ltoreq.y.ltoreq.70, and
0.ltoreq.z.ltoreq.65.
18. A polarizing plate having a polarizing film protected with the
antireflection film according to claim 15.
19. An image display device having the antireflection film
according to claim 15 disposed as an outermost surface thereof.
20. An image display device having the polarizing plate according
to claim 18 disposed as an outermost surface thereof.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a fine inorganic oxide dispersion
having fine inorganic oxide particles dispersed stably and a
coating composition containing the same. The invention further
relates to an optical film, particularly an antireflection film,
formed of the coating composition. The invention still further
relates to an optical film, particularly a polarizing plate and an
image display device having an antireflection film.
BACKGROUND OF THE INVENTION
[0002] Compounding organic or inorganic materials into adhesives,
exterior coatings, hard coats, antireflection coatings, and the
like has been studied to improve scratch resistance and strength
after cure, adhesion to substrates, and the like.
[0003] In mixing an organic material and an inorganic material, it
is necessary to prevent undesired agglomeration of the inorganic
material. One of the methods generally followed is to disperse an
inorganic material in a solvent compatible with an organic material
and mix the dispersion and the organic material to prepare a
coating composition for forming a coating film. In order to secure
stable performance, it is important that the inorganic material be
stably dispersed in the solvent. In other words, it is important to
control the hydrophilicity/hydrophobic- ity or steric hindrance of
the surface of the inorganic material. Surface treatment of fine
inorganic oxide particles with an alkoxysilane is known. For
example, Ganryo Bunsan Gijutu Hyomenshori to Bunsanzai no Tukaikata
oyobi Bunsansei Hyoka, Technical Information Institute Co., Ltd.,
1999 describes a technique of dispersing inorganic particles in an
organic solvent with the aid of a silane coupling agent. The
technique is insufficient in terms of stability of a resultant
dispersion, nevertheless.
[0004] In combining an organic material particularly of
polymerization cure system and inorganic particles, use of an
alkoxysilane having a polymerizable group and/or a
hydrolysis-condensation product thereof has been attracting
attention. For instance, JP-A-9-169847 proposes a combined use of a
specific polyalkoxypolysiloxane and a polymerizable silane coupling
agent. However, the reaction between the polyalkoxypolysiloxane and
the polymerizable silane coupling agent hardly proceeds
sufficiently for achieving a high ratio of introducing the
polymerizable group so that the resulting cured product is not
satisfactory in scratch resistance or strength. JP-A-940909
proposes use of a partial co-hydrolysis-condensation product of an
alkoxysilane having an organic functional group and a
tetraalkoxysilane, but the coating composition containing the same
has insufficient storage stability, still leaving room for further
improvement.
[0005] An optical film, particularly an antireflection film is
generally disposed in front of displays, such as cathode ray tube
displays (CRTs), plasma display panels (PDPs), electroluminescence
displays (ELDs), and liquid crystal displays (LCDs), whereby to
prevent contrast reduction or reduction of visibility due to
reflection of ambient light by making use of optical
interference.
[0006] Antireflection films for that application are manufactured
by forming a low reflective layer with a proper thickness on a
substrate and, if desired, other layers including a high reflective
layer, a middle reflective layer, and a hard coat layer, between
the low reflective layer and the substrate. To achieve a low
reflectance, it is desirable that the low reflective layer be made
of a material having as low a refractive index as possible.
Disposed as an outermost layer of displays, the antireflection film
is required to have high scratch resistance. To secure high scratch
resistance with as small a thickness as about 100 nm, the
antireflection film should exhibit strength per se and adhesion to
an underlying layer.
[0007] Means for reducing a refractive index of a material include
introducing fluorine and decreasing the density (by making voids),
but both approaches are accompanied by reductions in film strength
(scratch resistance) and adhesion. It has therefore been a
difficult problem to satisfy both the requirements for low
refractive index and high scratch resistance.
[0008] JP-A-11-189621, JP-A-11-228631, and JP-A-2000-313709
disclose techniques for providing a film with a reduced frictional
coefficient and improved scratch resistance by introducing a
polysiloxane structure into a fluoropolymer. The technique is
effective to some extent in improving scratch resistance but is
still insufficient for improving scratch resistance of a coating
film that essentially lacks film strength and interfacial
adhesion.
[0009] JP-A-2003-222704 teaches that addition of a silane coupling
agent to a low refractive layer material containing a fluoropolymer
provides a coating film with markedly improved scratch resistance.
However, because a silane coupling agent having a low boiling point
vaporizes while being applied and dried, it must be added in an
excess corresponding to the evaporation loss, which makes it
difficult to obtain stable performance.
SUMMARY OF THE INVENTION
[0010] An object of the present invention is to provide a stable,
fine dispersion of inorganic oxide particles and a coating
composition containing the same.
[0011] Another object of the invention is to provide an optical
film, particularly an antireflection film, having improved scratch
resistance while maintaining sufficient antireflection
performance.
[0012] Still another object of the invention is to provide an
optical film, particularly a polarizing plate and an image display
device having an antireflection film.
[0013] As a result of extensive investigations, the present
inventors have found that the above objects of the invention are
accomplished by the following fine inorganic oxide dispersion,
coating composition, optical film, an antireflection film, a
polarizing plate and an image display device.
[0014] The present invention provides, in its first aspect, a fine
inorganic oxide dispersion having dispersed in an organic solvent
fine inorganic oxide particles surface-treated with a hydrolyzate
and/or a partial condensate of an organosilane compound represented
by formula (I):
(R.sup.10).sub.m--Si(X).sub.4-m (I)
[0015] wherein R.sup.10 represents a substituted or unsubstituted
alkyl group or a substituted or unsubstituted aryl group; X
represents a hydroxyl group or a hydrolyzable group, and m
represents an integer of 1 to 3. The surface treatment is carried
out in the presence of (a) an acid catalyst and/or (b) a metal
chelate compound having Zr, Ti or Al as a center metal and an
alcohol represented by formula: R.sup.3OH (wherein R.sup.3
represents an alkyl group having 1 to 10 carbon atoms) and/or a
compound represented by formula: R.sup.4COCH.sub.2COR.sup.5
(wherein R.sup.4 represents an alkyl group having 1 to 10 carbon
atoms; and R.sup.5 represents an alkyl group having 1 to 10 carbon
atoms or an alkoxy group having 1 to 10 carbon atoms) as a
ligand.
[0016] The present invention also provides, in its second aspect, a
process of producing a fine dispersion of inorganic oxide particles
in an organic solvent, including the steps of (1) surface treating
inorganic oxide particles with a hydrolyzate and/or a partial
condensate of an organosilane compound represented by formula (I)
shown above in an organic solvent having a small ketone solvent
content in the presence of (a) an acid catalyst and/or (b) the
above-described metal chelate compounds and (2) replacing the
organic solvent used for the surface treatment with an organic
solvent having an increased ketone solvent content.
[0017] The present invention also provides, in its third aspect, a
fine inorganic oxide dispersion obtained by the above-described
process.
[0018] In a preferred embodiments of the fine inorganic oxide
dispersion of the invention, the inorganic oxide particles are
surface treated with the hydrolyzate and/or partial condensate of
the organosilane compound represented by formula (I) and a compound
having a fluoroalkyl group and/or a fluorine-containing aromatic
group.
[0019] The organosilane compound represented by formula (I), the
compound having a fluoroalkyl group and/or a fluorine-containing
aromatic group, or both of them are preferably a
fluorine-containing silane coupling agent represented by formula
(1):
(Rf-L.sub.i).sub.n--Si(R.sup.11).sub.n-4 (1)
[0020] wherein Rf represents a straight-chain, branched or cyclic
fluoroalkyl group having 1 to 20 carbon atoms or a
fluorine-containing aromatic group having 6 to 14 carbon atoms;
L.sub.1 represents a divalent linking group having 10 or fewer
carbon atoms; R.sup.11 represents a hydroxyl group or a
hydrolyzable group; and n represents an integer of 1 to 3.
[0021] The fluorine-containing silane coupling agent of formula (1)
is preferably represented by formula (2):
C.sub.nF.sub.2n+1--(CH.sub.2).sub.m--Si(R).sub.3 (2)
[0022] wherein n represents an integer of 1 to 10; m represents an
integer 1 to 5; and R represents an alkoxy group having 1 to 5
carbon atoms or a halogen atom.
[0023] In a preferred embodiment of the fine organic oxide
dispersion of the invention, the organosilane silane compound of
formula (I) is represented by formula (II): 1
[0024] wherein R.sup.10 and X are as defined above; R.sup.1
represents a hydrogen atom, a methyl group, a methoxy group, an
alkoxycarbonyl group, a cyano group, a fluorine atom or a chlorine
atom; Y represents a single bond, --COO--, --CONH-- or --O--; L
represents a divalent linking group; and n represents 0 or 1.
[0025] In a preferred embodiment of the fine organic oxide
dispersion of the invention, the inorganic oxide particles are
silica particles, particularly hollow silica particles.
[0026] The present invention also provides, in its fourth aspect, a
coating composition containing the above-described fine inorganic
oxide dispersion and a film-forming composition. The film forming
composition contains a compound having an ethylenically unsaturated
group. The compound having an ethylenically unsaturated group is
preferably the main component of the film forming composition.
[0027] The present invention also provides, in its fifth aspect, an
optical film having a transparent substrate and a layer of the
above-described coating composition provided on the substrate.
[0028] In a preferred embodiment of the optical film, the inorganic
oxide particles in the layer are hollow particles having a
refractive index of 1.20 to 1.46, particularly hollow silica
particles having a refractive index of 1.17 to 1.40.
[0029] The optical film includes, as a preferred embodiment, an
antireflection film having an antireflection layer containing a low
refractive layer on the transparent substrate, and the low
refractive layer is the layer formed of the above-described coating
composition.
[0030] In a preferred embodiment of the antireflection film, the
inorganic oxide particles in the coating composition are hollow
silica particles the average particle size of which is 30% to 150%
of the thickness of the low refractive layer.
[0031] In another preferred embodiment of the antireflection film,
the coating composition of the low refractive layer preferably
contains a fluoropolymer represented by formula (A): 2
[0032] wherein L represents a linking group having 1 to 10 carbon
atoms; m represents 0 or 1; X represents a hydrogen atom or a
methyl group; A represents a repeating unit derived from at least
one vinyl monomer; and x, y, and z represent a mole percent of the
respective repeating units in ranges 30.ltoreq.x.ltoreq.60,
5.ltoreq.y.ltoreq.70, and 0.ltoreq.z.ltoreq.65.
[0033] The present invention also provides, in its sixth aspect, a
polarizing plate having a polarizing film protected with the
antireflection film.
[0034] The present invention also provides, in its seventh aspect,
an image display device having the antireflection film or the
polarizing plate disposed as an outermost surface thereof.
[0035] The inorganic oxide dispersion according to the present
invention has high dispersion stability. A coating composition
containing the inorganic oxide dispersion and a film forming
composition provides an optical film with no haze and high scratch
resistance. The optical film of the present invention, especially a
display using the antireflective film exhibit excellent visibility
with little reflection of ambient light or objects on the viewer's
side.
BRIEF DESCRIPTION OF THE DRAWING
[0036] FIG. 1 schematically illustrates a coating system
configuration for producing an antireflection film of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0037] The fine inorganic oxide dispersion of the present invention
has surface-treated inorganic oxide particles in an organic
solvent. The inorganic oxide particles are surface treated with a
hydrolyzate and/or a partial condensate of an organosilane compound
represented by formula (I):
(R.sup.10).sub.m--Si(X).sub.4-m (I)
[0038] wherein R.sup.10 represents a substituted or unsubstituted
alkyl group or a substituted or unsubstituted aryl group; X
represents a hydroxyl group or a hydrolyzable group; and m
represents an integer of 1 to 3. The dispersion is characterized in
that the surface treatment of the inorganic oxide particles is
carried out in the presence of (a) an acid catalyst, (b) a metal
chelate compound, or both of (a) and (b).
[0039] The surface treatment is performed by bringing the inorganic
oxide particles with the organosilane compound (I) and, if
necessary, water in the presence of (a) an acid catalyst having a
hydrolyzing function and/or (b) a metal chelate compound having a
condensing function. The organosilane compound may have previously
been partially hydrolyzed or partially condensed. The organosilane
compound undergoes hydrolysis followed by partial condensation, and
the resultant hydrolyzate and/or partial condensate modifies the
surface of the inorganic oxide particles. The particles thus
surface treated exhibit improved dispersibility to provide a stable
dispersion in an organic solvent.
[0040] The metal chelate compound is a compound having Zr, Ti or Al
as a center metal and an alcohol represented by formula: R.sup.3OH
(wherein R.sup.3 represents an alkyl group having 1 to 10 carbon
atoms) and/or a compound represented by formula:
R.sup.4COCH.sub.2COR.sup.5 (wherein R.sup.4 represents an alkyl
group having 1 to 10 carbon atoms; and R.sup.5 represents an alkyl
group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10
carbon atoms) as a ligand.
[0041] The organosilane compound used in the invention, which is
represented by formula (I), will be described in detail.
[0042] In formula (I), R.sup.10 represents a substituted or
unsubstituted alkyl group or a substituted or unsubstituted aryl
group. The alkyl group preferably contains 1 to 30, still
preferably 1 to 16, particularly preferably 1 to 6, carbon atoms,
including methyl, ethyl, propyl, isopropyl, hexyl, t-butyl,
sec-butyl, hexyl, decyl, and hexadecyl. The aryl group includes
phenyl and naphthyl, with phenyl being preferred.
[0043] X represents a hydroxyl group or a hydrolyzable group.
Examples of the hydrolyzable group include an alkoxy group
(preferably one having 1 to 5 carbon atoms, e.g., methoxy or
ethoxy), a halogen atom (e.g., Cl, Br or I), and R.sup.2COO
(wherein R.sup.2 represents a hydrogen atom or an alkyl group
having 1 to 5 carbon atoms, e.g., CH.sub.3COO or
C.sub.2H.sub.5COO). X is preferably an alkoxy group, particularly
methoxy or ethoxy.
[0044] m represents an integer of 1 to 3. When there are two or
more R.sup.10s or Xs in formula (I), R.sup.10s or Xs may be the
same or different. m is preferably 1 or 2, still preferably 1.
[0045] The substituent of the substituted alkyl or aryl group as
R.sup.10 includes, but is not limited to, a halogen atom (e.g.,
fluorine, chlorine or bromine), a hydroxyl group, a mercapto group,
a carboxyl group, an epoxy group, an alkyl group (e.g., methyl,
ethyl, isopropyl, propyl or t-butyl), an aryl group (e.g., phenyl
or naphthyl), an aromatic heterocyclic group (e.g., furyl,
pyrazolyl or pyridyl), an alkoxy group (e.g., methoxy, ethoxy,
isopropoxy or hexyloxy), an aryloxy group (e.g., phenoxy), an
alkylthio group (e.g., methylthio or ethylthio), an arylthio group
(e.g., phenylthio), an alkenyl group (e.g., vinyl or 1-propenyl),
an acyloxy group (e.g., acetoxy, acryloyloxy or methacryloyloxy),
an alkoxycarbonyl group (e.g., methoxycarbonyl or ethoxycarbonyl),
an aryloxycarbonyl group (e.g., phenoxycarbonyl), a carbamoyl group
(e.g., carbamoyl, N-methylcarbamoyl, N,N-dimethylcarbamoyl or
N-methyl-N-octylcarbamoyl), and an acylamino group (e.g.,
acetylamino, benzoylamino, acrylamino or methacrylamino). These
substituents may have a further substituent if possible.
[0046] When there are two or more R.sup.10s, it is preferred that
at least one of them be a substituted alkyl or aryl group. Of the
organosilane compounds of formula (I), those having a vinyl
polymerizable substituent which are represented by formula (II)
shown below are preferred. 3
[0047] wherein R.sup.10 and X are as defined for formula (I);
R.sup.1 represents a hydrogen atom, a methyl group, a methoxy
group, an alkoxycarbonyl group, a cyano group, a fluorine atom or a
chlorine atom; Y represents a single bond, an ester group, an amido
group, an ether group or a urea group; L represents a divalent
linking group; and n represents 0 or 1.
[0048] The alkoxycarbonyl group as R.sup.1 includes methoxycarbonyl
and etboxycarbonyl. R.sup.1 is preferably a hydrogen atom, a methyl
group, a methoxy group, a methoxycarbonyl group, a cyano group, a
fluorine atom or a chlorine atom, still preferably a hydrogen atom,
a methyl group, a methoxycarbonyl group, a fluorine atom or a
chlorine atom, particularly preferably a hydrogen atom or a methyl
group.
[0049] Y is preferably a single bond, an ester group or an amido
group, still preferably a single bond or an ester group,
particularly preferably an ester group.
[0050] Examples of the linking group L include a substituted or
unsubstituted alkylene group, a substituted or unsubstituted
arylene group, a substituted or unsubstituted alkylene group having
a linking group (e.g., ether, ester or amido) in the chain thereof
or a substituted or unsubstituted arylene group having a linking
group in the inside thereof. L is preferably a substituted or
unsubstituted alkylene group having 2 to 10 carbon atoms, a
substituted or unsubstituted arylene group having 6 to 20 carbon
atoms or an alkylene group having 3 to 10 carbon atoms and
containing a linking group in the chain thereof, still preferably
an unsubstituted alkylene group, an unsubstituted arylene group or
an alkylene group having an ether or ester linking group in the
chain thereof, particularly preferably an unsubstituted alkylene
group or an alkylene group having an ether or ester linking group
in the chain thereof. The substituent of the substituted alkylene
or arylene group includes a halogen atom, a hydroxyl group, a
mercapto group, a carboxyl group, an epoxy group, an alkyl group,
and an aryl group. These substituents may have a further
substituent if possible.
[0051] R.sup.10 is preferably a substituted or unsubstituted alkyl
group or a substituted or unsubstituted aryl group, still
preferably an unsubstituted alkyl group or an unsubstituted aryl
group.
[0052] X is preferably a halogen atom, a hydroxyl group or an
unsubstituted alkoxy group, still preferably a chlorine atom, a
hydroxyl group or an unsubstituted alkoxy group having 1 to 6
carbon atoms, particularly preferably a hydroxyl group or an alkoxy
group having1 to 3 carbon atoms. A methoxy group is the most
preferred. The two or three Xs may be the same or different. n is
preferably 0.
[0053] The organosilane compounds of formula (1) can be used either
individually or as a combination of two or more thereof. Specific
but non-limiting examples of the compounds represented by formula
(I) and (II) are shown below. 4567
[0054] Particularly preferred of the compounds listed above are M-1
(acryloyloxypropyltrimethoxysilane), M-2
(methacryloyloxypropyltrimethoxy- silane), and M-25
(glycidoxypropyltrimethoxysilane).
[0055] The amount of the organosilane compound (I) to be used in
the invention is not critical but is preferably 1% to 300% by
weight, still preferably 2% to 100% by weight, particularly
preferably 5% to 50% by weight, based on the inorganic oxide
particles to be surface treated; or preferably 1 to 300 mol %,
still preferably 5 to 300 mol %, particularly preferably 10 to 200
mol %, based on the hydroxyl group content on the surface of the
inorganic oxide particles. With the amount of the organosilane
compound (I) falling within the above ranges, there is produced a
sufficient stabilizing effect on the inorganic oxide dispersion,
and the dispersion will form a high strength coating film.
[0056] It is preferred that the inorganic oxide particles be
surface-modified with not only the organosilane compound
hydrolyzate and/or partial condensate but also a compound having a
fluoroalkyl group or a fluorine-containing aromatic group. It is
preferred that the inorganic oxide particles and the compound
having a fluoroalkyl group or a fluorine-containing aromatic group
react with each other. It is still preferred that the surface of
the inorganic oxide particles be chemically treated with a
fluorine-containing surface active agent, a fluorine-containing
coupling agent, and the like. It is particularly preferred that the
surface of the inorganic oxide particles be chemically treated with
a fluorine-containing coupling agent. The fluorine-containing
coupling agent preferably includes alkoxymetal compounds, such as
titan coupling agents and silane coupling agents, particularly
fluorine-containing silane coupling agents. A fluorine-containing
silane coupling agent represented by formula (1) shown below is
especially effective.
(Rf-L.sub.1).sub.n--Si(R.sup.11).sub.n-4 (1)
[0057] wherein Rf represents a straight-chain, branched or cyclic
fluoroalkyl group having 1 to 20 carbon atoms or a
fluorine-containing aromatic group having 6 to 14 carbon atoms;
L.sub.1 represents a divalent linking group having 10 or fewer
carbon atoms; R.sup.11 represents a hydroxyl group or a
hydrolyzable group, and n represents an integer of 1 to 3.
[0058] The surface treatment with a fluorine-containing silane
coupling agent is preferably such that a partial condensate is
formed between a component derived from the fluorine-containing
silane coupling agent and the inorganic oxide particles. The
surface treatment with a fluorine-containing silane coupling agent
brings about improved stability of the fine inorganic oxide
particles in the dispersion and improved dispersibility of the
particles in a coating film. A combined use of the organosilane
compound represented by formula (II) and the fluorine-containing
silane coupling agent represented by formula (1) is particularly
effective in improving particle dispersibility in a coating film
and scratch resistance of a coating film.
[0059] Since the fluorine-containing silane coupling agent of
formula (1) is included in the organosilane compound of formula
(I), surface treatment with the fluorine-containing organosilane
compound of formula (I) alone is effective as well.
[0060] In formula (1), Rf preferably represents a straight-chain,
branched or cyclic fluoroalkyl group having 3 to 10 carbon atoms,
still preferably a straight-chain fluoroalkyl group having 4 to 8
carbon atoms. L.sub.1 preferably represents a straight-chain or
branched and substituted or unsubstituted alkylene group having 1
to 10 carbon atoms, still preferably 1 to 5 carbon atoms, that may
contain a linking group (e.g., ether, ester or amido) in the chain
thereof. Preferred substituents of the substituted alkylene group
include a halogen atom, a hydroxyl group, a mercapto group, a
carboxyl group, an epoxy group, an alkyl group, and an aryl group.
R.sup.11 is preferably an alkoxy group having 1 to 5 carbon atoms
or a halogen atom, still preferably a methoxy group, an ethoxy
group or a chlorine atom.
[0061] Of the fluorine-containing silane coupling agents of formula
(1), preferred are those represented by formula (2):
C.sub.nF.sub.2n-1--(CH.sub.2).sub.m--Si(R).sub.3 (2)
[0062] wherein n represents an integer of 1 to 10; m represents an
integer 1 to 5, and R represents an alkoxy group having 1 to 5
carbon atoms or a halogen atom.
[0063] In formula (2), n is preferably 4 to 10, m is preferably 1
to 3; and R is preferably a methoxy group, an ethoxy group or a
chlorine atom.
[0064] Specific but non-limiting examples of the
fluorine-containing silane coupling agents represented by formula
(1), preferably formula (2), are shown below. 89
[0065] These fluorine-containing silane coupling agents can be
synthesized by, for example, the process taught in
JP-A-11-189599.
[0066] The fluorine-containing silane coupling agents of formula
(1) can be used either individually or as a combination of two or
more thereof. The fluorine-containing silane coupling agents of
formula (1) are preferably used in a total amount of 1% by 100% by
weight, still preferably 2% to 80% by weight, particularly
preferably 5% to 50% by weight, based on the inorganic oxide
particles.
[0067] Where the organosilane compound of formula (II) is used in
combination with the fluorine-containing silane coupling agent of
formula (1), a preferred weight ratio of the fluorine-containing
silane coupling agent (1) to the organosilane compound (II) is 99:1
to 1:99, still preferably 75:25 to 5:95, particularly preferably
50:50 to 25:75.
[0068] Where two or more organosilane compounds, including the
fluorine-containing silane coupling agents, are used in the
invention, they may be added all at once, or one or some of them
are added in the beginning of the surface treatment, and the rest
of them are added after a certain progress of the surface treating
reaction. It is also preferred that the organosilane compound is
previously subjected to partial condensation before being brought
into contact with the inorganic oxide particles.
[0069] The above-described organosilane compound is made to act on
the surface of inorganic oxide particles to make the particles more
dispersible. More specifically, a component derived from the silane
coupling agent is bonded to the surface of inorganic oxide
particles through hydrolysis and/or condensation reaction of the
organosilane compound.
[0070] The surface treatment of inorganic oxide particles with a
hydrolyzate and/or a partial condensate of the organosilane
compound can be effected with or without a solvent. In using a
solvent, the concentration of the organosilane compound hydrolyzate
and/or partial condensate is appropriately decided. An organic
solvent is preferred for uniformly mixing the components. Suitable
organic solvents include alcohols, aromatic hydrocarbons, ethers,
ketones, and esters.
[0071] The solvent is preferably one capable of dissolving the
organosilane compound hydrolyzate and/or partial condensate and the
catalyst. It is preferred that the organic solvent used for the
surface treatment also serve as at least part of the medium of a
coating composition containing the inorganic oxide dispersion of
the invention. The solvent is preferably not to impair the
solubility or dispersibility of other components incorporated into
the coating composition, such as a fluoropolymer hereinafter
described.
[0072] Useful alcohol solvents include monohydric alcohols
(preferably saturated aliphatic alcohols having 1 to 8 carbon
atoms) and dihydric alcohol, such as methanol, ethanol, n-propyl
alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol,
tert-butyl alcohol, ethylene glycol, diethylene glycol, triethylene
glycol, ethylene glycol monobutyl ether, and ethylene glycol
monoethyl ether acetate.
[0073] Useful hydrocarbon solvents include benzene, toluene, and
xylene. Useful ether solvents include tetrahydrofuran and dioxane.
Useful ketone solvents include acetone, methyl ethyl ketone, methyl
isobutyl ketone, and diisobutyl ketone. Useful ester solvents
include ethyl acetate, propyl acetate, butyl acetate, and propylene
carbonate.
[0074] These organic solvents can be used either individually or as
a combination of two or more thereof. The concentration of the
organosilane compound in the solvent used for the surface treatment
is not particularly limited but usually ranges from 0.1% to 70% by
weight, preferably 1% to 50% by weight.
[0075] In a preferred embodiment of the present invention, fine
inorganic oxide particles are dispersed in an alcohol solvent and
surface treated as described above, followed by replacement of the
dispersing medium (i.e., the alcohol solvent) with an aromatic
hydrocarbon solvent or a ketone solvent. For securing compatibility
with a binder that is used for coating and dispersion stability, a
ketone solvent is preferable to an aromatic hydrocarbon one. It is
desirable for the organic solvent used in the surface treatment of
the inorganic oxide particles to have a small ketone solvent
content. Specifically, the content of a ketone solvent in the total
solvent for the surface treatment is preferably not higher than 30%
by volume, still preferably 10% by volume or lower, particularly
preferably 5% by volume or lower. After the surface treatment, the
ketone solvent content in the total solvent is preferably increased
to 50% by volume or higher, still preferably 80% by volume or
higher, particularly preferably 90% by volume or higher, by solvent
replacement.
[0076] The surface treatment of inorganic oxide particles with the
organosilane compound hydrolyzate and/or condensate is preferably
carried out in the presence of a catalyst. Suitable catalysts
include inorganic acids, such as hydrochloric acid, sulfuric acid,
and nitric acid; organic acids, such as oxalic acid, acetic acid,
formic acid, methanesulfonic acid, and toluenesulfonic acid;
inorganic bases, such as sodium hydroxide, potassium hydroxide, and
ammonia; organic bases, such as triethylamine and pyridine; and
metal alkoxides, such as aluminum triisopropoxide and zirconium
tetrabutoxide. From the viewpoint of production stability and
storage stability of the inorganic oxide dispersion, an acid
catalyst (including organic ones and inorganic ones) and/or a metal
chelate compound is/are used in the present invention. Hydrochloric
acid, sulfuric acid, and organic acids having a dissociation
constant (pKa; in water at 25.degree. C., hereinafter the same) of
4.5 or smaller are preferably used as an acid catalyst.
Hydrochloric acid, sulfuric acid, and organic acids having a pKa of
3.0 or smaller are still preferred. Hydrochloric acid, sulfuric
acid, and organic acids having a pKa of 2.5 or smaller are
particularly preferred. Organic acids having a pKa of 2.5 or
smaller are especially preferred. Methanesulfonic acid, oxalic
acid, phthalic acid, and malonic acid are desirable. Oxalic acid is
the most preferred.
[0077] Where the organosilane compound has an alkoxy group as a
hydrolyzable group, and an organic acid is used as an acid
catalyst, because the carboxyl group or sulfo group of the organic
acid supplies a proton, the surface treatment can be accomplished
with a reduced amount of water. Specifically, the requisite amount
of water will be 0 to 2 mol, preferably 0 to 1.5 mol, still
preferably 0 to 1 mol, particularly preferably 0 to 0.5 mol, per
mole of the alkoxide group of the organosilane compound. Where an
alcohol solvent is used as a medium for the surface treatment, the
surface treatment could be achieved in a substantially water-free
system.
[0078] The amount of the inorganic acid catalyst to be used ranges
from 0.01 to 10 mol %, preferably 0.1 to 5 mol %, based on the
hydrolyzable group content. In the case of the organic acid
catalyst, the optimal amount to be used varies depending on the
amount of water added. Where water is added, the amount of the
organic acid to be used is 0.01 to 10 mol %, preferably 0.1 to 5
mol %, based on the hydrolyzable group content. When substantially
no water is added, the amount of the organic acid is 1 to 500 mol
%, preferably 10 to 200 mol %, still preferably 20 to 200 mol %,
particularly preferably 50 to 150 mol %, especially preferably 50
to 120 mol %, based on the hydrolyzable group content.
[0079] The surface treatment is usually conducted by stirring the
reaction system at 15.degree. to 100.degree. C. It is advisable to
select the reaction temperature according to the reactivity of the
organosilane compound.
[0080] The metal chelate compounds that can be used in the
invention have Zr, Ti or Al as a center metal and an alcohol
represented by formula: R.sup.3OH (wherein R.sup.3 represents an
alkyl group having 1to 10 carbon atoms) and/or a compound
represented by formula: R.sup.4COCH.sub.2COR.sup- .5 (wherein
R.sup.4 represents an alkyl group having 1 to 10 carbon atoms; and
R.sup.5 represents an alkyl group having 1 to 10 carbon atoms or an
alkoxy group having 1 to 10 carbon atoms) as a ligand. These metal
chelate compounds serve to accelerate condensation reaction of the
organosilane compound. Preferred of these metal chelate compounds
are those represented by formulae:
Zr(OR.sup.3).sub.p1(R.sup.4COCHCOR.sup.5).sub.p2
Ti(OR.sup.3).sub.q1(R.sup.4COCHCOR.sup.5).sub.q2
Al(OR.sup.3).sub.r1(R.sup.4COCHCOR.sup.5).sub.r2
[0081] wherein R.sup.3, R.sup.4, and R.sup.5 are as defined above;
and p1, p2, q1, q2, r1, and r2 each represent an integer for
forming a bi-, tetra- or hexadentate complex around the respective
center metal.
[0082] In each of the formulae representing the metal chelate
compounds, R.sup.3 and R.sup.4 may be the same or different and
include ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl,
and n-pentyl. Examples of R.sup.5 include the above-enumerated
alkyl groups and, in addition, methoxy, ethoxy, n-propoxy,
isopropoxy, n-butoxy, sec-butoxy, and t-butoxy.
[0083] Specific examples of the metal chelate compounds include
zirconium chelate compounds, such as tri(n-butoxy)(ethyl
acetoacetato)zirconium, di(n-butoxy)bis(ethyl
acetoacetato)zirconium, n-butoxytris(ethyl acetoacetato)zirconium,
tetrakis(n-propyl acetoacetato)zirconium, tetrakis(acetyl
acetoacetato)zirconium, and tetrakis(ethyl acetoacetate)zirconium;
titanium chelate compounds, such as di(isopropoxy)bis(ethyl
acetoacetato)titanium, di(isopropoxy)bis(acetyl acetato)titanium,
and di(isopropoxy)bis(acetylacetone)titanium; and aluminum chelate
compounds, such as di(isopropoxy)(ethyl acetoacetato)aluminum,
di(isopropoxy)(acetyl acetonato)aluminum, isopropoxybis(ethyl
acetoacetato)aluminum, isopropoxybis(acetyl acetonato)aluminum,
tris(ethyl acetoacetato)aluminum, tris(acetyl acetonato)aluminum,
and mono(acetyl acetonato)bis(ethyl acetoacetato)aluminum.
[0084] Preferred of them are tri(n-butoky)(ethyl
acetoacetato)zirconium, di(isopropoxy)bis(acetyl
acetonato)titanium, di(isopropoxy)(ethyl acetoacetato)aluminum, and
tris(ethyl acetbacetato)aluminum. These metal chelate compounds can
be used either individually or as a combination of two or more
thereof. Partial hydrolysis products of the metal chelate compounds
are useful as well.
[0085] From the standpoint of condensation reaction rate and film
strength, the metal chelate compound is preferably used in an
amount of 0.01% to 50% by weight, still preferably 0.1% to 50% by
weight, particularly preferably 0.5% to 10% by weight, based on the
organosilane compound.
[0086] The dispersion or the coating composition of the present
invention preferably contains (c) a .beta.-diketone compound and/or
a .beta.-keto ester compound both represented by formula:
R.sup.4COCH.sub.2COR.sup.5 (wherein R.sup.4 and R.sup.5 are as
defined above) (hereinafter sometimes referred to as "component
(c)") in addition to the organosilane compound and (a) the acid
catalyst and/or (b) the metal chelate compound. Component (c) acts
as a stability improver in the dispersion or the coating
composition. The .beta.-diketone compound and/or .beta.-keto ester
compound coordinates to the center metal of the metal chelate
compound (i.e., the zirconium, titanium and/or aluminum compound).
It is considered to follow that the accelerating action of the
metal chelate compound on the condensation reaction of the
organosilane compound is suppressed thereby to provide the
resulting dispersion or coating composition with improved storage
stability.
[0087] Examples of the .beta.-diketone compound and/or .beta.-keto
ester compound as component (c) include acetylacetone, methyl
acetoacetate, ethyl acetoacetate, n-propyl acetoacetate, isopropyl
acetoacetate, n-butyl acetoacetate, sec-butyl acetoacetate, t-butyl
acetoacetate, 2,4-hexanedione, 2,4-heptanedione, 3,5-heptanedione,
2,4-octanedione, 2,4-nonanedione, and 5-methylhexanedione. Ethyl
acetoacetate and acetylacetone are preferred of them, with
acetylacetone being still preferred. These .beta.-diketone
compounds and .beta.-keto ester compounds can be used either
individually or as a mixture of two or more thereof. Component (c)
is preferably used in an amount of 2 mol or more, still preferably
3 to 20 mol, per mole of the metal chelate compound. Addition of
less than 2 mol is substantially ineffective.
[0088] The inorganic oxide particles to be surface treated in the
invention preferably include particles of an oxide of at least one
element selected from the group consisting of silicon, aluminum,
zirconium, titanium, zinc, germanium, indium, tin, antimony, and
cerium.
[0089] Examples of the oxide are silica, alumina, zirconia,
titanium oxide, zinc oxide, germanium oxide, indium oxide, tin
oxide, indium-tin oxide (ITO), antimony oxide, and cerium oxide.
Silica, alumina, zirconia, and antimony oxide are preferred from
their high hardness. These inorganic oxides can be used either
individually or as a mixture thereof. The fine inorganic oxide
dispersion of the present invention is obtained by dispersing the
aforementioned surface-treated fine inorganic oxide particles in an
organic solvent. The inorganic oxide particles are preferably
surface treated in the form of a dispersion in a dispersion medium.
The dispersing medium is preferably an organic solvent in view of
compatibility with other components or dispersing capabilities.
Suitable organic solvents as a dispersing medium include alcohols,
such as methanol, ethanol, isopropyl alcohol, butanol, and octanol;
ketones, such as acetone, methyl ethyl ketone, methyl isobutyl
ketone, and cyclohexanone; esters, such as ethyl acetate, butyl
acetate, ethyl lactate, .gamma.-butyrolactone, propylene glycol
monomethyl ether acetate, and propylene glycol monoethyl ether
acetate; ethers, such as ethylene glycol monomethyl ether and
diethylene glycol monobutyl ether; aromatic hydrocarbons, such as
benzene, toluene, and xylene; and amides, such as
dimethylformamide, dimethylacetamide, and N-rnethylpyrrolidone.
Preferred of them are methanol, isopropyl alcohol, butanol, methyl
ethyl ketone, methyl isobutyl ketone, ethyl acetate, butyl acetate,
toluene, and xylene.
[0090] The inorganic oxide particles preferably have a number
average particle size of 1 to 2000 nm, still preferably 3 to 200
nm, particularly preferably 5 to 100 nm. With the number average
particle size exceeding 2000 nm, the coating composition tends to
provide a cured product with reduced transparency or a coating film
with poor surface conditions. The dispersion or the coating
composition may contain various surface active agents or amine
compounds for the purpose of improving the dispersibility of the
particles.
[0091] Commercial products of silicon oxide (e.g., silica)particles
that can be used in the invention include those supplied in
colloidal form, such as Methanol Silica Sol, MA-ST-MS, EPA-St,
IPA-ST-MS, IPA-ST-L, IPA-ST-ZL, IPA-ST-UP, EG-ST, NPC-ST-30,
MEK-ST, MEK-ST-L, MIBK-ST, NBA-ST, XBA-ST, DMAC-ST, ST-UP, ST-OUP,
ST-20, ST-40, ST-C, ST-N, ST-O, ST-50, and ST-OL, all available
from Nissan Chemical Industries, Ltd., and hollow silica CS60-IPA
available from Catalysts & Chemicals Industries Co., Ltd.; and
those supplied in powder form, such as Aerosil 130, Aerosil 300,
Aerosil 380, Aerosil TT600, and Aerosil OX50, all available from
Nippon Aerosil Co., Ltd., Sildex H31, H32, H51, H52, H121, and H122
available from Asahi Glass Co., Ltd., E220A and E220 available from
Nippon Silica Kogyo KK, Sylysia 470 available from Fuji Silysia
Chemical Ltd., and SG Flake available from Nippon Sheet Glass Co.,
Ltd.
[0092] Commercial products of other inorganic oxide particles that
can be used in the invention include waterborne dispersions of
alumina, such as Alumina Sol 100, 200 and 520 from Nissan Chemical
Industries, Ltd.; 2-propanol dispersions of alumina, such as
AS-150I from Sumitomo Osaka Cement Co., Ltd.; toluene dispersions
of alumina, such as AS-150T from Sumitomo Osaka Cement; toluene
dispersions of zirconia, such as HXU-110JC from Sumitomo Osaka
Cement; waterborne dispersions of zinc antimonate, such as Celnax
from Nissan Chemical; alumina, titanium oxide, tin oxide, indium
oxide or zinc oxide powders or solventbome dispersions exemplified
by NanoTek series from C.I. Kasei Co., Ltd.; waterborne dispersions
of antimony-doped tin oxide, such as SN-100D from Ishihara Sangyo
Kaisha, Ltd.; ITO powders available from Mitsubishi Materials
Corp.; and waterborne dispersions of cerium oxide, such as Needral
from Taki Chemical Co., Ltd.
[0093] The inorganic oxide particles may be amorphous or may have a
spherical shape, a rod shape, a plate shape or a fibrous shape and
may be solid or hollow and porous or nonporous. The oxide particles
are preferably spherical and/or hollow. Hollow silica particles
will be described later. The oxide particles preferably have a BET
specific surface area (measured using nitrogen as adsorption gas)
of 10 to 1000 m.sup.2/g, still preferably 100 to 500 m.sup.2/g. The
dispersion of the inorganic oxide particles to be surface treated
may be prepared by dispersing an inorganic oxide powder in an
organic solvent, or any of the above-recited fine dispersions known
in the art may be utilized as such.
[0094] In case where an inorganic oxide powder is dispersed in a
dispersing medium, a dispersant can be used. A dispersant having an
anionic group is preferred. Effective anionic groups include those
having an acidic proton, such as a carboxyl group, a sulfo group, a
phosphono group, and a sulfonamido group, and their salt forms. A
carboxyl group, a sulfo group, a phosphono group, and their salt
forms are preferred. A carboxyl group and a phosphono group are
still preferred. A dispersant can have two or more anionic groups
for ensuring the effect of improving the dispersibility. The
average number of the anionic groups per molecule is preferably 2
or greater, still preferably 5 or greater, particularly preferably
10 or greater. The anionic groups present per molecule may be the
same or different.
[0095] The dispersant can contain a crosslinkable or polymerizable
functional group in its molecule. A crosslinkable or polymerizable
functional group includes ethylenically unsaturated groups capable
of addition reaction and polymerization reaction initiated by a
radical species (e.g., (meth)acryloyl, allyl, styryl or vinyloxy),
cationically polymerizable groups (e.g., epoxy, oxatanyl or
vinyloxy), and polycondensation reactive groups (e.g., hydrolyzable
silyl groups and N-methylol). Functional groups having an
ethylenically unsaturated group are preferred.
[0096] A dispersing machine can be used to pulverize inorganic
oxide particles. Useful dispersing machines include a sand grinder
mill (e.g., a bead mill with pins), a high-speed impeller mill, a
pebble mill, a roller mill, an attritor, and a colloid mill. A sand
grinder mill and a high-speed impeller mill are recommended. The
oxide particles may previously be dispersed by means of a ball
mill, a three-roll mill, a kneader, an extruder, etc.
[0097] The above-described organic solvent dispersion of
surface-treated inorganic oxide particles can. be compounded with a
film-forming composition to make a coating composition. The coating
composition containing the inorganic oxide dispersion forms a layer
of an optical film. The coating composition is particularly
suitable to form a low refractive layer of an antireflection
film.
[0098] The optical film according to the present invention has a
transparent substrate (hereinafter sometimes referred to as a base
film) and one or more functional layers provided thereon. At least
one of the functional layers is formed of the coating composition
of the invention.
[0099] The functional layers of an optical film as referred to here
include an antistatic layer, a hard coat layer, an antireflection
layer, an antiglare layer, an optical compensation layer, an
orientation layer, and a liquid crystal layer. The antireflection
film according to the present invention has an antireflection layer
provided on a transparent substrate and, if necessary, a hard coat
layer provided between the substrate and the antireflection layer.
The antireflection layer is composed of at least one layer, usually
a stack of layers, of which the refractive index, the thickness,
the number, and the order of stacking are designed so as to reduce
the reflectance by optical interference.
[0100] The simplest layer structure of the antireflection film is a
substrate having formed thereon an antireflection layer composed
solely of a low refractive layer. To further reduce the
reflectance, the antireflection layer is desirably composed of at
least one high refractive layer having a higher refractive index
than the substrate and at least one low refractive layer having a
lower refractive index than the substrate. Known antireflection
films have a two-layer structure having a high refractive layer and
a low refractive layer stacked on a substrate in that order or a
three-layer structure having a middle refractive layer, a high
refractive layer, and a low refractive layer stacked on a substrate
in that order (the middle refractive layer having a higher
refractive index than the substrate or a hard coat layer and a
lower refractive index than the high refractive layer). Layer
structures with more layers are also proposed. An antireflection
film having, on a substrate, a hard coat layer, a middle refractive
layer, a high refractive layer, and a low refractive layer in that
order is particularly preferred for its durability, optical
characteristics, cost, and productivity. The antireflection film of
the invention may further have an antiglare layer, an antistatic
layer, and the like.
[0101] The structures the antireflection film of the invention can
have are listed below.
[0102] 1) Base film/low refractive layer
[0103] 2) Base film/antiglare layer/low refractive layer
[0104] 3) Base film/bard coat layer/antiglare layer/low refractive
layer
[0105] 4) Base film/hard coat layer/high refractive layer/low
refractive layer
[0106] 5) Base film/hard coat layer/middle refractive layer/high
refractive layer/low refractive layer
[0107] 6) Base film/antiglare layer/high refractive layer/low
refractive layer
[0108] 7) Base film/antiglare layer/middle refractive layer/high
refractive layer/low refractive layer
[0109] 8) Base filming/antistatic layer/hard coat layer/middle
refractive layer/high refractive layer/low refractive layer
[0110] 9) Antistatic layer/base film/hard coat layer/middle
refractive layer/high refractive layer/low refractive layer
[0111] 10) Base film/antistatic layer/antiglare layer/middle
refractive layer/high refractive layer/low refractive layer
[0112] 11) Antistatic layer/base film/antiglare layer/middle
refractive layer/high refractive layer/low refractive layer
[0113] 12) Antistatic layer/base film/antiglare layer/high
refractive layer/low refractive layer/high refractive layer/low
refractive layer
[0114] The layer structure of the antireflection film of the
invention is not limited to the above list as long as it reduces
the reflectance through optical interference. The high refractive
layer may be a light scattering layer having no antiglare
performance. The antistatic layer is preferably a layer containing
conductive polymer particles or metal oxide fine particles (e.g.,
SnO.sub.2, ITO), which can be formed by application of a coating
composition or plasma treatment under atmospheric pressure.
[0115] The film-forming composition making up the coating
composition according to the present invention preferably contains
a compound having an ethylenically unsaturated group. Such a
compound is preferably a main film-forming binder of the film
forming composition from the viewpoint of film strength, stability
of the coating composition, and productivity of the coating film.
The term "main film forming binder" as used herein means a binder
component forming a proportion of at least 10% by weight in total
film forming components other than the inorganic particles. The
proportion of the main film forming binder in the total film
forming components is preferably 20% to 100% by weight, still
preferably 30% to 95% by weight.
[0116] The film forming binder is preferably a polymer having a
saturated hydrocarbon chain or a polyether chain as a main chain,
still preferably a polymer having a saturated hydrocarbon chain as
a main chain. A homo- or copolymer of a monomer having two or more
ethylenically unsaturated groups per molecule is a preferred binder
polymer having a saturated hydrocarbon chain as a main chain and a
crosslinked structure. To increase the refractive index, the
monomer preferably contains an aromatic ring or at least one atom
selected from halogen atoms other than fluorine, a sulfur atom, a
phosphorus atom, and a nitrogen atom in its structure.
[0117] Examples of the monomer having two or more ethylenically
unsaturated groups include esters between polyhydric alcohols and
(meth)acrylic acid, such as ethylene glycol di(meth)acrylate,
1,4-cyclohexane diacrylate, pentaerythritol tetra(meth)acrylate,
pentaerythritol tri(meth)acrylate, trimethylolpropane
tri(meth)acrylate, trimethylolethane tri(meth)acrylate,
dipentaerythritol tetra(meth)acrylate, dipentaerythritol
penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate,
pentaerythritol hexa(meth)acrylate, 1,2,3-cyclohexane
tetramethacrylate, polyurethane polyacrylate, and polyester
polyacrylate; vinylbenzene and derivatives thereof, such as
1,4-divinylbenzene, 2-acryloylethyl 4-vinylbenzoate, and
1,4-divinylcyclohexanone; vinylsulfones, such as divinylsulfone;
acrylamides, such as methylenebisacrylamide; and methacrylamides.
The terms "(meth)acrylic" and "(meth)acrylate" as used herein mean
"acrylic or methacrylic" and "acrylate or methacrylate",
respectively. These monomers can be used either individually or as
a combination of two or more thereof.
[0118] Examples of monomers providing high refractive polymers
include bis(4methacryloylthiophenyl) sulfide, vinylnaphthalene,
vinyl phenyl sulfide, and 4-methacryloxyphenyl-4'-methoxyphenyl
thioether. These monomers are also employable either individually
or as a combination of two or more thereof.
[0119] Polymerization of the monomer having an ethylenically
unsaturated group can be carried out by irradiation with an
ionizing radiation or heating in the presence of a photo radical
initiator or a thermal radical initiator.
[0120] Useful photo radical initiators include acetophenones,
benzoins, benzophenones, phosphine oxides, ketals, anthraquinones,
thioxanthones, azo compounds, peroxides, 2,3-dialkyldione
compounds, disulfide compounds, fluoroamine compounds, and aromatic
sulfoniums. Examples of the acetophenones are
2,2-diethoxyacetophenone, p-dimethylacetophenone, 1-hydroxydimethyl
phenyl ketone, 1-hydroxycyclohexyl phenyl ketone,
2-methyl-4-methylthio-2-morpholinopropiophenone, and
2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone. Examples
of the benzoins are benzoin benzenesulfonate, benzoin
toluenesulfonate, benzoin methyl ether, benzoin ethyl ether, and
benzoin isopropyl ether. Examples of the benzophenones are
benzophenone, 2,4-dichlorobenzophenone, 4,4-dichlorobenzophenone,
and p-chlorobenzophenone. Examples of the phosphine oxides include
2,4,6-trimethylbenzoyldiphenylphosphine oxide.
[0121] Additional examples of useful photo radical initiators are
described in Saishin UV Kouka Gijyutu, Technical Information
Institute Co., Ltd., 1991, 159.
[0122] Commercially available photo-cleaving radical initiators
that are preferably used in the invention include Irgacure series
(651, 184, and 907) from Ciba-Geigy Japan Ltd.
[0123] The photo polymerization initiator is preferably used in an
amount of 0.1 to 15 parts by weight, still preferably 1 to 10 parts
by weight, per 100 parts by weight of the polyfunctional monomer. A
photo sensitizer may be used in addition to the photo
polymerization initiator. Suitable photo sensitizers include
n-butylamine, triethylamine, tri-n-butylphosphine, Michler's
ketone, and thioxanthone.
[0124] The thermal radical initiators include organic or inorganic
peroxides, and organic azo and diazo compounds. Examples of the
organic peroxides are benzoyl peroxide, halogen-substituted benzoyl
peroxides, lauroyl peroxide, acetyl peroxide, dibutyl peroxide,
cumene hydroperoxide, and butyl hydroperoxide. Examples of the
inorganic peroxides are hydrogen peroxide, ammonium persulfate, and
potassium persulfate. Examples of the azo compounds are
2-azobisisobutyronitrile, 2-azobispropionitrile, and
2-azobiscyclohexanedinitrile. Examples of the diazo compounds are
diazoaminobenzene and p-nitrobenzene diazonium.
[0125] As stated above, polymers having a polyether as a main chain
are also useful as a film forming binder. The polymer having a
polyether main chain is preferably a ring open polymerization
product of a polyfunctional epoxy compound. Ring open
polymerization of a polyfunctional epoxy compound is performed by
irradiation with an ionizing radiation or heating in the presence
of a photo acid generator or a thermal acid generator.
[0126] The optical film of the invention will be explained below,
by taking the antireflection film as an example.
[0127] A monomer having a crosslinking functional group may be used
in addition to, or in place of, the monomer having two or more
ethylenically unsaturated group to produce a polymer having a
crosslinking functional group, which reacts to introduce a
crosslinked structure into the binder polymer.
[0128] Examples of the crosslinking functional group include an
isocyanate group, an epoxy group, an aziridine group, an oxazoline
group, an aldehyde group, a carbonyl group, a hydrazine group, a
carboxyl group, a methylol group, and an active methylene group.
Other monomers useful to introduce a crosslinked structure include
vinylsulfonic acid, acid anhydrides, cyanoacrylate derivatives,
melamines, etherified methylols, esters, urethanes, and metal
alkoxides such as tetramethoxysilane. Functional groups capable of
developing crosslinkability upon being decomposed, such as a
blocked isocyanate group, are also effective. In other words, the
term "crosslinking functional group" as used herein includes not
only a group ready to crosslink but a group that decomposes to
develop crosslinking reactivity.
[0129] The binder polymer having such a crosslinking functional
group forms a crosslinked structure on being heated after
application.
[0130] The low refractive layer of the antireflection film is
preferably formed by using the coating composition of the
invention.
[0131] The low refractive layer is preferably a cured film of a
copolymer essentially comprising a repeating unit derived from a
fluorine-containing vinyl monomer and a repeating unit having a
(meth)acryloyl group in the side chain thereof (hereinafter
sometimes referred to as a fluoropolymer). It is preferred that at
least 60% by weight, still preferably 70% by weight or more,
particularly preferably 80% by weight or more, of the solids
content of the coating film be derived from the copolymer. In order
to achieve high film strength as well as a low refractive index, a
curing agent, such as a polyfunctional (meth)acrylate, is
preferably added to the coating composition within an amount
compatible with the other components.
[0132] The low refractive layer preferably has a refractive index
of 1.20 to 1.46, still preferably 1.25 to 1.46, particularly
preferably 1.30 to 1.46.
[0133] The low refractive layer preferably has a thickness of 50 to
200 nm, still preferably 70 to 100 nm. The haze of the low
refractive layer is preferably 3% or less, still preferably 2% or
less, particularly preferably 1% or less. The low refractive layer
preferably has a pencil hardness of H or higher, still preferably
2H or higher, particularly preferably 3H or higher, as measured
under a load of 500 g.
[0134] In order to assure antifogging properties of the optical
film, the water contact angle of the surface of the low refractive
layer is preferably 90.degree. or greater, still preferably
95.degree. or greater, particularly preferably 100.degree. or
greater.
[0135] The fluoropolymer that is preferably used to form the low
refractive layer will be described in more detail.
[0136] Examples of the fluorine-containing vinyl monomer include
fluoroolefins (e.g., fluoroethylene, vinylidene fluoride,
tetrafluoroethylene, and hexafluoropropylene), partially or
completely fluorinated alkyl ester derivatives of (meth)acrylic
acid (e.g., Viscoat 6FM available from Osaka Organic Chemical
Industry Ltd. and R-202 available from Daikin Industries, Ltd.),
and partially or completely fluorinated vinyl ethers.
Perfluoroolefins are preferred. Hexafluoropropylene is particularly
preferred from the standpoint of refractive index, solubility,
transparency, and availability. As the copolymerization ratio of
the fluorine-containing vinyl monomer increases, the refractive
index becomes smaller, but the film strength decreases. From this
viewpoint, the fluorine-containing vinyl monomer is preferably used
to give a fluorine content of 20% to 60% by weight, still
preferably 25% to 55% by weight, particularly preferably 30% to 50%
by weight, in the resulting copolymer.
[0137] The fluoropolymer preferably contains a repeating unit
having a (meth)acryloyl group in the side chain thereof. As the
ratio of the (meth)acryloyl group-containing repeating unit
increases, the film strength increases, but the refractive index
also increases. A preferred ratio of the (meth)acryloyl
group-containing repeating unit in the copolymer is generally 5% to
90% by weight, still preferably 30% to 70% by weight, particularly
preferably 40% to 60% by weight, while varying depending on the
fluorine-containing vinyl monoomer to be combined with.
[0138] In addition to the fluorine-containing vinyl monomer unit
and the (meth)acryloyl group-containing unit, the copolymer can
contain one or more kinds of repeating units derived from other
vinyl monomers for improving adhesion to a substrate, adjusting the
glass transition temperature (Tg) that contributes to the film
strength, and improving the solubility in a solvent, transparency,
slip properties, antidust and antifouling properties, and the like.
The ratio of the other vinyl monomer units in the copolymer is
preferably up to 65 mol %, still preferably 0 to 40 mol %,
particularly preferably 0 to 30 mol %.
[0139] Examples of useful other vinyl monomers include olefins
(e.g., ethylene, propylene, isoprene, vinyl chloride, and
vinylidene chloride), acrylic esters (e.g., methyl acrylate, ethyl
acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate),
methacrylic esters (e.g., methyl methacrylate, ethyl methacrylate,
butyl methacrylate, and 2-hydroxyethyl methacrylate), styrene
derivatives (e.g., styrene, p-hydroxymethylstyrene, and
p-methoxystyrene), vinyl ethers (e.g., methyl vinyl ether, ethyl
vinyl ether, cyclohexyl vinyl ether, hydroxyethyl vinyl ether, and
hydroxybutyl vinyl ether), vinyl esters (e.g., vinyl acetate, vinyl
propionate, and vinyl cinnamate), unsaturated carboxylic acids
(eg., acrylic acid, methacrylic acid, crotonic acid, maleic acid,
and itaconic acid), acrylamides (e.g., N,N-di methyl acrylamide,
N-t-butylacrylamide, and N-cyclohexylacryl amide), methacrylamides
(e.g., N,N-dimethylmethacrylamide), and acrylonitrile.
[0140] Of the above-described fluoropolymers preferred are those
represented by formula 10
[0141] wherein L represents a linking group having 1 to 10 carbon
atoms; m represents 0 or 1; X represents a hydrogen atom or a
methyl group; A represents a repeating unit derived from at least
one vinyl monomer; and x, y, and z represent mole percents of the
respective repeating units in ranges 30.ltoreq.x.ltoreq.60,
5.ltoreq.y.ltoreq.70, and 0.ltoreq.z.ltoreq.65.
[0142] In formula (A), L is preferably a linking group having 1 to
6 carbon atoms, still preferably a linking group having 2 to 4
carbon atoms. The linking group may be straight-chain or branched
or may contain a cyclic structure. The linking group may contain a
hetero atom selected from O, N, and S. Examples of preferred
linking groups L are *--(CH.sub.2).sub.2--O--**,
*--(CH.sub.2).sub.2--NH--**, *--(CH.sub.2).sub.4--O--**,
*--(CH.sub.2).sub.6--O--**,
*--(CH.sub.2).sub.2--O--(CH.sub.2).sub.2--O--**,
*--CONH--(CH.sub.2).sub.- 3--O--**,
*--CH.sub.2CH(OH)CH.sub.2--O--**, and *--CH.sub.2CH.sub.2OCONH(C-
H.sub.2).sub.3--O--** (wherein * indicates the position at which to
link to the main chain of the polymer; and ** indicates the
position at which to link to the (meth)acryloyl group). X is
preferably a hydrogen atom from the viewpoint of curing
reactivity.
[0143] The repeating unit represented by A is not particularly
limited as long as it is derived from a vinyl monomer or monomers
copolymerizable with hexafluoropropylene. The vinyl monomer or
monomers providing the unit A can be chosen according to the
purpose, for example, improvement of adhesion to a substrate,
adjustment of the glass transition temperature (Tg) that
contributes to the film strength, and improvement of solubility in
a solvent, transparency, slip properties, and antidust or
antifouling properties.
[0144] Examples of suitable vinyl monomers providing the unit A
include vinyl ethers (e.g., methyl vinyl ether, ethyl vinyl ether,
t-butyl vinyl ether, cyclohexyl vinyl ether, isopropyl vinyl ether,
hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, glycidyl vinyl
ether, and allyl vinyl ether), vinyl esters (e.g., vinyl acetate,
vinyl propionate, and vinyl butyrate), (meth)acrylates (e.g.,
methyl (meth)acrylate, ethyl (meth)acrylate, hydroxyethyl
(meth)acrylate, glycidyl methacrylate, allyl (meth)acrylate, and
(meth)acryloyloxypropyltrimethoxysilane), styrene derivatives
(e.g., styrene and p-hydroxymethylstyrene), and unsaturated
carboxylic acids (eg., crotonic acid, maleic acid, and itaconic
acid) and derivatives thereof. Preferred of them are vinyl ether
derivatives and vinyl ester derivatives, with the vinyl ether
derivatives being particularly preferred.
[0145] x, y, and z preferably represent numbers in ranges:
35.ltoreq.x.ltoreq.55, 30.ltoreq.y.ltoreq.60, and
0.ltoreq.z.ltoreq.20, still preferably 40.ltoreq.x.ltoreq.55,
40.ltoreq.y.ltoreq.55, and 0.ltoreq.z.ltoreq.10.
[0146] Of the copolymers represented by formula (A) preferred are
those represented by formula (B): 11
[0147] wherein X, x, and y are as defined for formula (A)
(preferred ranges of X, x, and y are the same as those described
above); n represents an integer of 2 to 10; B represents a
repeating unit derived from at least one vinyl monomer; and z1 and
z2 represent mole percents of the respective repeating units in
ranges: 0.ltoreq.z1.ltoreq.65 and 0.ltoreq.z2.ltoreq.65.
[0148] In formula (B), n is preferably 2 to 6, still preferably 2
to 4. Examples of the repeating unit B are the same as those
enumerated for the repeating unit A. z1 is preferably 0 to 30,
still preferably 0 to 10, and z2 is preferably 0 to 10, still
preferably 0 to 5.
[0149] The fluoropolymer represented by formula (A) (preferably
formula (B)) is synthesized by, for example, introducing a
(meth)acryloyl group into a copolymer containing a
hexafluoropropylene component and a hydroxyalkyl vinyl ether
component. The copolymer can be prepared by the process described
in JP-A-2004-45462.
[0150] Examples of the fluoropolymers that are preferably used to
form the low refractive layer of the antireflection film are listed
below.
1 12 Molecular Average Molecular Weight x y m L1 X Mn
(.times.10.sup.4) P-1 50 0 1 *--CH.sub.2CH.sub.2O-- H 3.1 P-2 50 0
1 *--CH.sub.2CH.sub.2O-- CH.sub.3 4.0 P-3 45 5 1
*--CH.sub.2CH.sub.2O-- H 2.8 P-4 40 10 1 *--CH.sub.2CH.sub.2O-- H
3.8 P-5 30 20 1 *--CH.sub.2CH.sub.2O-- H 5.0 P-6 20 30 1
*--CH.sub.2CH.sub.2O-- H 4.0 P-7 50 0 0 -- H 11.0 P-8 50 0 1
*--C.sub.4H.sub.8O-- H 0.8 P-9 50 0 1 13 H 1.0 P-10 50 0 1 14 H 7.0
P-11 50 0 1 *--CH.sub.2CH.sub.2NH-- H 4.0 P-12 50 0 1 15 H 4.5 P-13
50 0 1 16 CH.sub.3 4.5 P-14 50 0 1 17 CH.sub.3 5.0 P-15 50 0 1 18 H
3.5 P-16 50 0 1 19 H 3.0 P-17 50 0 1 20 H 3.0 P-18 50 0 1 21
CH.sub.3 3.0 P-19 50 0 1 22 CH.sub.3 3.0 P-20 40 10 1
*--CH.sub.2CH.sub.2O-- CH.sub.3 0.6 23 Number Average Molecular
Weight a b c L1 A Mn (.times.10.sup.4) P-21 55 45 0
*--CH.sub.2CH.sub.2O--** -- 1.8 P-22 45 55 0
*--CH.sub.2CH.sub.2O--** -- 0.8 P-23 50 45 5 24 25 0.7 P-24 50 45 5
26 27 4.0 P-25 50 45 5 28 29 4.0 P-26 50 40 10
*--CH.sub.2CH.sub.2O--** 30 4.0 P-27 50 40 10
*--CH.sub.2CH.sub.2O--** 31 4.0 P-28 50 40 10
*--CH.sub.2CH.sub.2O--** 32 5.0 33 Number Average Molecular Weight
x y z1 z2 n X B Mn (.times.10.sup.4) P-29 50 40 5 5 2 H 34 5.0 P-30
50 35 5 10 2 H 35 5.0 P-31 40 40 10 10 4 CH.sub.3 36 4.0 37 Number
Average Molecular Weight a b Y Z Mn (.times.10.sup.4) P-32 45 5 38
39 4.0 P-33 40 10 40 41 4.0 *indicates the polymer main chain side.
**indicates the acryoyl group side.
[0151] The above-described copolymers are synthesized by preparing
a precursor, such as a hydroxyl-containing polymer, through various
polymerization techniques, including solution polymerization,
precipitation polymerization, suspension polymerization, bulk
polymerization, and emulsion polymerization, and introducing a
(meth)acryloyl group into the precursor through polymer reaction.
The polymer reaction is conducted by known processes, such as a
batch process, a semi-continuous process, and a continuous
process.
[0152] The polymerization is initiated by using a radical initiator
or irradiating with light or a radiation. The polymerization
processes and the methods of polymerization initiation are
described, e.g., in Teiji Turuta, Kobunshi Gosei Houhou, Rev. Ed.,
Nikkan Kogyo Shinbun, 1971 and Takayuki Ohtu and Masaetu Kinoshita,
Kobunshi Gosei no Jikkenho, Kagaku Dojin, 1972, 124-154.
[0153] Of the above-recited polymerization techniques, solution
polymerization using a radical initiator is preferred. Various
organic solvents can be used to effect solution polymerization.
Examples of useful solvents include ethyl acetate, butyl acetate,
acetone, methyl ethyl ketone, methyl isobutyl ketone,
cyclohexanone, tetrahydrofuran, dioxane, N,N-dimethylformamide,
N,N-dimethylacetarnide, benzene, toluene, acetonitrile, methylene
chloride, chloroform, dichloroethane, methanol, ethanol,
1-propanol, 2-propanol, and 1-butanol, and mixtures thereof. A
mixed solvent of the organic solvent and water is also useful.
[0154] The polymerization temperature is decided in connection with
a desired molecular weight of the polymer produced, the kind of the
initiator used, and the like. It may be lower than 0.degree. C. or
higher than 100.degree. C., but preferably ranges from 50.degree.
to 100.degree. C.
[0155] The reaction pressure is decided appropriately. It usually
ranges from about 0.98 to 98 kPa, preferably about 0.98 to 30 kPa.
The reaction time is usually about 5 to 30 hours.
[0156] Solvents that can be used for re-precipitation of the
resulting polymer preferably include isopropyl alcohol, hexane, and
methanol.
[0157] The inorganic oxide particles that are suited for use in the
low refractive layer of the antireflection layer will then be
described. The amount of the inorganic oxide particles to be
applied is preferably 1 to 100 mg/m.sup.2, still preferably 5 to 80
mg/m.sup.2, particularly preferably 10 to 60 mg/m.sup.2. Where the
amount of the inorganic particles applied is too small, the effect
of improving scratch resistance is insubstantial. Where too large
an amount of the particles is applied, the surface of the low
refractive layer has fine unevenness, which can result in
deterioration of appearance (including black tone or density) and
integrated reflectance.
[0158] It is desirable of necessity that the inorganic oxide
particles, being used in the low refractive layer, have a low
refractive index. Specifically, the aforementioned surface-treated
inorganic oxide particles, including solid particles and hollow
particles, such as silica or hollow silica particles, dispersed in
an organic solvent which have a low refractive index are used. The
silica particles preferably have an average particle size of 30% to
150%, still preferably 35% to 80%, particularly preferably 40% to
60%, of the thickness of the low refractive layer. When the low
refractive layer is 100 nm thick, for example, the silica particles
preferably have an average particle size of 30 to 150 nm, still
preferably 35 to 80 nm, particularly preferably 40 to 60 nm.
[0159] If the silica particles are too small, the scratch
resistance improving effect would be insubstantial. If the
particles are too large, the low refractive layer would suffer from
fine surface unevenness, resulting in deterioration of appearance
(such as black tone or density) and integrated reflectance. The
silica particles may be either crystalline or amorphous and may be
mono-dispersed particles or poly-dispersed particles containing
agglomerates as long as the particle size requirement is satisfied.
While spherical particles are the most desirable, irregularly
shaped particles are useful as well. The average particle size of
the inorganic particles as referred to here is the one measured
with a Coulter counter.
[0160] In order for the low refractive layer to have a low
refractive index, hollow silica particles are preferred. Hollow
silica particles have a refractive index of 1.17 to 1.40,
preferably 1.17 to 1.35, still preferably 1.17 to 1.30. The term
"refractive index of hollow silica particles" does not mean the
refractive index of only the outer shell forming the individual
hollow particles (i.e., the silica per se) but the one of the
spherical particle as a whole. Taking the radius of the cavity of a
hollow particle and the outer radius of the shell as "a" and "b",
respectively, the cavity ratio x is calculated according to
equation.
x=(4.pi.a.sup.3/3)/(4.pi.b.sup.3/3).times.100
[0161] The cavity ratio x is preferably 10% to 60%, still
preferably 20% to 60%, particularly preferably 30% to 60%. As the
cavity ratio increases, the shell thickness decreases to reduce the
refractive index, but the strength of the particles reduces.
Therefore, particles having a refractive index smaller than 1.17
are impractical from the standpoint of scratch resistance.
[0162] The refractive index of the hollow silica particles was
measured with an Abbe refractometer (supplied by Atago KK).
[0163] Incorporation of hollow particles into the low refractive
layer is effective in reducing the refractive index of the layer.
The low refractive layer containing hollow particles preferably has
a refractive index of 1.20 to 1.46, still preferably 1.25 to 1.41,
particularly preferably 1.30 to 1.39.
[0164] It is preferred to use fine silica particles whose average
particle size is smaller than 25% of the thickness of the low
refractive layer (hereinafter referred to as small-size silica
particles) in combination with silica particles having the
above-recited average particle size (hereinafter referred to as
large-size silica particles). The small-size silica particles can
exist in the interstices between the large-size silica particles
and thereby serve to support the large size silica particles.
[0165] When the thickness of the low refractive layer is 100 nm,
the small-size silica particles preferably have an average particle
size of 1 to 20 nm, still preferably 5 to 15 nm, particularly
preferably 10 to 15 nm. Use of silica particles of that size is
preferred from the viewpoint of material cost and the supporting
effect.
[0166] To secure improved film strength, it is preferred to add to
the coating composition a hydrolyzate and/or a partial condensate
of an organosilane compound. To synthesize a partial condensate of
an organosilane compound (hereinafter referred to as sol), the acid
catalysts and the metal chelate compounds useful in the surface
treatment of the inorganic oxide particles can be used. The sol is
preferably added in an amount of 2% to 200% by weight, still
preferably 5% to 100% by weight, particularly preferably 10% to 50%
by weight, based on the inorganic oxide particles.
[0167] It is preferred to reduce the surface free energy of the
antireflection layer for improving antifouling properties. This can
be done by incorporating into the low refractive layer a
fluorine-containing compound or a compound having a polysiloxane
structure, such as a reactive group-containing polysiloxane.
Reactive group-containing polysiloxanes are available from
Shin-Etsu Chemical Co., Ltd. under trade names KF-100T, X-22-169AS,
KF-102, X-22-3701IE, X-22-164B, X-22-5002, X-22-173B, X-22-174D,
X-22-167B, and X-22-161AS; from Toagosei Co., Ltd. under trade
names AK-5, AS-30, and AK-32; and from Chisso Corp. under trade
names Silaplane FM 0725 and Silaplane FM 0721. The silicone
compounds described in JP-A-2003-112383, Tables 2 and 3 are also
useful. A preferred amount of the polysiloxane to be added is 0.1%
to 10% by weight, still preferably 1% to 5% by weight, based on the
total solids content of the low refractive layer.
[0168] The low refractive layer is preferably formed by applying
the coating composition having a fluorine-containing compound and
other optional components dissolved or dispersed therein and curing
the applied layer either simultaneously with application or after
application and drying. Curing is accomplished by crosslinking or
polymerization induced by irradiation with an ionizing radiation
(e.g., light or an electron beam) or heating.
[0169] Where the low refractive layer is formed by crosslinking or
polymerization of an ionizing radiation-curing compound, the
crosslinking or polymerization reaction is preferably effected in
an atmosphere having an oxygen concentration controlled to 10% by
volume or lower. By so doing, a low refractive layer with high
physical strength and excellent chemical resistance requited of the
outermost layer can be formed. The oxygen concentration is
desirably 6% or lower, more desirably 4% or lower, particularly
desirably 2% or lower, most desirably 1% or lower, by volume.
[0170] The oxygen concentration control is preferably achieved by
replacing the air (about 79% nitrogen and about 21% oxygen) with
another gas, particularly nitrogen (i.e., purge with nitrogen).
[0171] The antireflective film of the invention preferably has a
high refractive layer provided on the substrate in addition to the
low refractive layer. The high refractive layer can be formed of a
binder;, matte particles for imparting antiglare properties, and an
inorganic filler for increasing a refractive index and film
strength and preventing shrinkage on crosslinking.
[0172] The matte particles, which are particles larger than filler
particles and are added for imparting antiglare properties, include
inorganic particles and resin particles having an average particle
size of 0.1 to 5.0 .mu.m preferably 1.5 to 3.5 .mu.m. The
difference in refractive index between the matte particles and the
binder is preferably 0.02 to 0.20, still preferably 0.04 to 0.10.
If the difference is too large, the layer would be cloudy. Too
small a difference results in a failure to exert sufficient light
scattering effect. The amount of the matte particles to be used
preferably ranges from 3% to 30% by weight, more preferably 5% to
20% by weight, based on the binder. If the matte particles are used
in too much an amount, the film would be cloudy. If added in too
small an amount, the matte particles cannot produce sufficient
light scattering effect.
[0173] Examples of suitable matte particles include particles of
inorganic compounds, such as silica and TiO.sub.2; and particles of
resins, such as acrylic resins, crosslinked acrylic resins,
polystyrene, crosslinked polystyrene, melamine resins, and
benzoguanamine resins. Crosslinked polystyrene particles,
crosslinked acrylic resin particles, and silica particles are
preferred. The matte particles may be spherical or amorphous.
[0174] Different kinds of matte particles can be used in
combination. When refractive index control is aimed at, it is
effective to use two or more kinds of matte particles different in
refractive index preferably by 0.02 to 0.10, still preferably 0.03
to 0.07. It is also possible to use a combination of relatively
large matte particles for securing antiglare performance and
relatively small matte particles for imparting another desired
optical property For instance, an optical film is required to be
free from an optical defect called glare when stuck to a high
precision display with a resolution of 133 ppi or more. Glare,
which is ascribed to a luminance distribution due to enlargement or
reduction of pixels by the fine surface unevenness (contributory to
anti-glare) of the film, is greatly reduced by a combination of
large matte particles for antiglare properties and matte particles
smaller than the large ones and having a different refractive index
from the binder.
[0175] It is preferred that the matte particles of a kind be
mono-dispersed. That is, it is preferred for the individual
particles to be as close as possible to each other in size.
Particles whose diameters are, for example, 20% or more greater
than the average particle size being taken as coarse particles, it
is desirable that the proportion of such coarse particles be not
more than 1%, more desirably 0.1% or less, most desirably 0.01% or
less, of the total number of particles. Matte particles having such
a narrow size distribution can be obtained by classifying the
particles as synthesized in a usual manner. Classification can be
performed repeatedly or to an increased degree to obtain a desired
particle size distribution.
[0176] The matte particles are used in the high refractive layer
preferably in an amount of 10 to 1000 mg/M.sup.2, still preferably
100 to 700 mg/m.sup.2. The particle size distribution of the matte
particles is measured with a Coulter counter, and the measured
distribution is converted to a particle number distribution.
[0177] In addition to the matte particles the high refractive layer
preferably contains an inorganic filler to increase the
refractivity and to suppress shrinkage on curing. The inorganic
filler includes oxides of at least one of titanium, zirconium,
aluminum, indium, zinc, tin, and antimony and has an average
particle size of 0.2 .mu.m or smaller, preferably 0.1 .mu.m or
smaller, still preferably 0.06 .mu.m or smaller. Where the high
refractive layer contains matte particles having a high refractive
index, it is preferred to incorporate silicon oxide particles into
the high refractive layer so as to increase the difference in
refractivity between the high-refractive matte particles and the
other part of the high refractive layer. A preferred particle size
of the silicon oxide particles is the same as that of the
inorganic-filler.
[0178] Specific examples of the inorganic filler useful in the high
refractive layer include TiO.sub.2, ZrO.sub.2, Al.sub.2O.sub.3,
In.sub.2O.sub.3, ZnO, SnO.sub.2, Sb.sub.2O.sub.3, ITO, and
SiO.sub.2. TiO.sub.2 and ZrO.sub.2 are preferred of them for their
high refractive indices. Titanium oxide particles are particularly
preferred for their high refractive index.
[0179] Where a coating composition contains a monomer and an
initiator, the coating film is irradiated with an ionizing
radiation or heated to cause the monomer to polymerize (cure)
thereby to form a middle refractive layer or a high refractive
layer with high scratch resistance and good adhesion. The average
particle size of the inorganic particles in the layer is preferably
20 to 120 nm, still preferably 30 to 100 nm, particularly
preferably 40 to 90 nm, taking into consideration haze, dispersion
stability, and moderate film surface roughness for adhesion to an
upper layer and, in the case of TiO.sub.2, for suppressing
photoactivity o TiO.sub.2.
[0180] Titanium dioxide particles to be used are preferably those
containing titanium dioxide as a main component and at least one
element selected from the group consisting of cobalt, aluminum, and
zirconium as a minor component. The term "main component" as used
above means a component of which the content is the highest of all
the other components making up the particles. The inorganic
particles containing titanium oxide as a main component preferably
have a refractive index of 1.90 to 2.80, still preferably 2.10 to
2.80, particularly preferably 2.20 to 2.80. The inorganic particles
containing titanium oxide as a main component preferably have a
primary particle size of 1 to 200 nm, still preferably 1 to 150 nm,
particularly preferably 1 to 100 nm, especially preferably 1 to 80
nm.
[0181] The particle size of the inorganic particles can be measured
by a light scattering method or from an electron micrograph. The
inorganic particles preferably have a specific surface area of 10
to 400 m.sup.2/g, still preferably 20 to 200 m.sup.2/g,
particularly preferably 30 to 150 m.sup.2/g
[0182] The inorganic particles containing titanium dioxide as a
main component preferably have a main structural form selected from
rutile, rutile/anatase, anatase, and amorphous. The particles are
particularly preferably those containing a rutile structure as a
main component. The term "main component" as used here means a
component the content of which is the highest of all the other
components making up the particles.
[0183] The inorganic particles containing titanium dioxide as a
main component and at least one element selected from cobalt,
aluminum, and zirconium as a minor component have the
photocatalysis attributed to titanium dioxide suppressed so that
the high refractive layer or the middle refractive layer containing
the particles may exhibit improved weather resistance. Cobalt is
preferred as a minor component. The inorganic particles containing
two or more of cobalt, aluminum and zirconium are also
preferred.
[0184] The inorganic filler can be surface treated with a silane
coupling agent or a titan coupling agent. A coupling agent
providing the surface of the filler particles with a functional
group reactive with a binder is preferably used. The inorganic
filler is preferably used in an amount of 10% to 90% by weight,
still preferably 20% to 80% by weight, particularly preferably 30%
to 70% by weight, based on the total weight of the high refractive
layer.
[0185] Since the inorganic filler is sufficiently smaller in
diameter than the wavelength of light, it does not cause light
scattering. Therefore, a disperse system of the filler in a binder
polymer behaves as an optically uniform substance.
[0186] The bulk (overall) refractive index of the high refractive
layer made of a binder and an inorganic filler is preferably 1.48
to 2.00, still preferably 1.50 to 1.80. The kinds and the
compounding ratio of the binder and the filler are selected so as
to result in a bulk refractive index in the above range. The
selection can be done through previous experimentation.
[0187] The antireflection film according to the present invention
has a haze of 3% to 70%, preferably 4% to 60%, and an average
reflectance of 3.0% or smaller, preferably 2.5% or smaller, in a
wavelength range of from 450 nm to 650 nm.
[0188] As long as the antireflection film has a haze and an average
reflectance falling within the above-recited respective ranges, it
exhibits satisfactory antiglare and antireflection performance
without being accompanied by deterioration of transmitted image
quality.
[0189] The transparent substrate that can be used in the optical
film of the invention is preferably a plastic film. Polymers
forming a plastic film substrate include cellulose esters, such as
cellulose triacetate and cellulose diacetate (e.g., TAC-TD80U and
TD80UF available from Fuji Photo Film Co., Ltd.), polyamide,
polycarbonate, polyesters, such as polyethylene terephthalate and
polyethylene naphthalate, polystyrene, polyolefins, norbornene
resins (e.g., Arton available from JSR Corp.), and amorphous
polyolefins (e.g., Zeonex available from Zeon Corp.). Preferred of
them are cellulose triacetate, polyethylene terephthalate, and
polyethylene naphthalate, with cellulose triacetate being
particularly preferred. A cellulose acylate film substantially free
of halogenated hydrocarbon (e.g., dichloromethane) is also a
preferred substrate for use in the invention. Such a cellulose
acylate film and a process of producing the same are disclosed in
Journal of Technical Disclosure 2001-1745 published by Japan
Institute of Invention and Innovation.
[0190] For applications to displays such as LCDs, the optical film
of the invention can have an adhesive layer provided on the back
side of the substrate thereof. As described later, the optical film
of the invention which uses a cellulose triacetate base film is
economically advantageous for use as at least one of protective
films for a polarizing film of a polarizing plate because a
polarizing film of a polarizing plate is commonly sandwiched in
between a pair of cellulose triacetate films.
[0191] For applications to displays as an outermost layer or for
applications as a protective film of polarizing plates, it is
preferred that the optical film such as the antireflection film be
subjected to saponification after the formation of an outermost
layer mainly comprising the fluoropolymer. Saponification is
carried out in a known manner, for example, by immersing the film
in an alkali solution for a proper period of time. After the
immersion, the film is thoroughly washed with water or immersed in
a dilute acid solution for neutralization to completely remove the
alkali component from the film. As a result of the saponification
treatment, the back side of the transparent substrate (opposite to
the outermost layer side) is made hydrophilic. The thus
hydrophilized surface is particularly advantageous for adhesion to
a polarizing film mainly comprising polyvinyl alcohol. In addition,
the hydrophilized surface is less attractive to dust and is
therefore advantageous for preventing dust in air from entering
between the substrate and the polarizing film and causing spot
defects.
[0192] The saponification treatment is preferably conducted so that
the back side of the substrate (opposite to the outermost layer
side of the optical film) may have a water contact angle of
40.degree. or smaller, still preferably 30.degree. or smaller,
particularly preferably 20.degree. or smaller.
[0193] The saponification treatment with an alkali is performed by
(1) immersing the transparent substrate having the functional layer
formed thereon in an alkali solution at least once or (2) coating
an alkali solution to the back side of the transparent substrate
having the functional layer formed thereon or the side of the
transparent substrate opposite to the side on which an
antireflection layer is to be provided, followed by heating, and
followed by washing and/or neutralization. The method (1) is
advantageous in that the film can be treated in the same manner as
with a general-purpose cellulose triacetate film. However, the
method (1) is disadvantageous in that the surface of the outermost
layer is also saponified (hydrolyzed with the alkali) and therefore
deteriorated and that the alkali solution, if remaining on the
antireflecting layer, can soil the surface of the antireflecting
layer. When these disadvantages are problematical, the method (2)
is recommended, in which only the back side of the film is
saponified.
[0194] A process of fabricating the optical film of the present
invention will be described taking, for instance, the production of
an antireflection film.
[0195] To begin with, coating compositions for the respective
layers are prepared. The coating compositions are applied on a
transparent substrate by dipping, air knife coating, curtain
coating, roller coating, wire bar coating, gravure coating or
extrusion (see U.S. Pat. No. 2,681,294) and dried by heating.
Gravure coating is advisable for applying a very small amount of a
coating composition to a uniform thickness as demanded in the
present invention. Inter alia, microgravure coating is recommended
for achieving a uniform coating thickness.
[0196] A slot die coating technique is also suitable for applying a
small amount of a coating composition to a uniform thickness. With
a slot die coater, it is relatively easy to control the film
thickness because the coating fluid is pre-metered. Additionally, a
slot die coater is a fully enclosed system that reduces evaporation
of the solvent. Two or more layers can be applied simultaneously by
slot die coating. In this regard, reference can be made to U.S.
Pat. Nos. 2,761,791, 2,941,898, 3,508,947, and 3,526,528 and Yuji
Harasaki, Coating Kogaku, Asakura Shoten, 1973, 253.
[0197] It is preferred for the production cost that at least two of
a plurality of optical layers constituting the antireflection layer
of the antireflection film be formed on a single web coating line
including the steps of feeding a web substrate, applying continuous
layers of the respective coating compositions on the moving
substrate, and taking up the coated substrate. Where the
antireflection layer is composed of three layers, the three layers
are preferably formed on such a single web coating line. The web
coating line is a line having in series any number of a set of a
work station and associated curing/drying equipment between an
unwind or feed station and a rewind station. The number of the set
is preferably equal to the number of the optical layers to be
formed.
[0198] FIG. 1 illustrates an example of a coating system
configuration. The web coating line shown in FIG. 1 has a first
work station (102), a first drying zone (103), a first UV
irradiator (104), a second work station (105), a second drying zone
(106), a second UV irradiator (107), a third work station (108), a
third drying zone (109), a third UV irradiator (110), and a
post-heating zone (111). between an unwind station (101) and a
rewind station (112). On this web coating line is produced a
multilayer film having up to three functional coating layers, for
example, a film having middle-refractive layer/high-refractive
layer/low-refractive layer, a film having hard coat
layer/high-refractive layer/low-refractive layer, or a film having
hard coat layer/antiglare layer/low-refractive layer. In a
preferred modification of the system, a middle-refractive layer and
a high-refractive layer are formed on a single web coating line
having two work stations, and the coated web is inspected for the
surface condition, film thickness, etc. The inspection data are fed
back to the system control to improve the yield. In another
modification, a dual-layer, antiglare antireflection film having an
antiglare layer and a low-refractive layer can be produced at low
cost on the web coating line having two work stations. In another
preferred modification, a four-layered antireflection film having a
hard coat layer, a middle-refractive layer, a high refractive
layer, and a low refractive layer can be produced at a markedly
reduced cost on a web coating line having four work stations. It
would be desirable from the standpoint of cost and space saving to
use only a UV curing resin as a film forming binder and to omit the
post heating zone.
[0199] Basically, a polarizing plate is structured in 3 layers; a
pair of protective films having a polarizing film sandwiched
therebetween. The optical film, especially the antireflection film
of the invention is preferably used as at least one of the
protective films protecting the polarizing film of a polarizing
plate. Using the optical film of the invention to serve as not only
an antireflection film but a protective film results in reduction
of production cost of polarizing plates. The polarizing plate
having the antireflection film of the invention as an outermost
layer prevents reflection of ambient light and has high scratch
resistance and excellent antifouling properties.
[0200] Polarizing films that can be used in the polarizing plate
include known polarizing films and those cut out of a polarizing
film of continuous length the absorption axis of which is neither
parallel nor perpendicular to the machine direction. A polarizing
film of continuous length the absorption axis of which is neither
parallel nor perpendicular to the machine direction is prepared as
follows. A continuously fed web of a polymer is held in tension by
its edges in a framework having a pair of engaging means and
widthwise stretched 1.1 to 20.0 times. The engaging means on
opposite sides move in the longitudinal direction of the web at the
respective speeds different by within 3%. As a result, the moving
direction of the web while being held by both edges describes a
curve so that the moving direction and the practical stretch
direction make an angle of 200 to 700 at the outlet of the
framework. The angle between the web moving direction and the
stretch direction is preferably 45.degree. for productivity.
[0201] For the details of the method of stretching a polymer web,
reference can be made to JP-A-2002-86554, paragraphs [0020] through
[0030].
[0202] The polarizing plate which has the antireflection film of
the invention as one of the surface protective films is suited for
applications to transmissive, reflective or semi-transmissive LCDs
(including twisted nematic (IN) mode, super twisted nematic (STN)
mode, vertical alignment (VA) mode, in-plane switching (IPS) mode,
optically compensated bend (OCB) mode, and electrically controlled
birefringence (ECB) mode).
[0203] The VA mode liquid crystal cells include not only (I) a
narrowly-defined VA mode liquid cell in which rod-like liquid
crystal molecules are aligned substantially vertically with no
voltage applied (in an off state) and aligned substantially
horizontally on voltage application (in an on state) (see
JP-A-2-176625) but also (2) a multi-domain vertical alignment (MVA)
mode liquid crystal cell having a widened viewing angle (see SID'
97, Digest of Tech. Papers, 28, 1997, 845), (3) an n-ASM mode
liquid crystal cell in which rod-like liquid crystal molecules are
aligned substantially vertically in an off state and oriented in a
twisted multi-domain mode in an on state (see Preprints of Japan
Liquid Crystal Symposium, 1998, 58-59), and (4) a survival mode
liquid crystal cell (released in LCD International '98).
[0204] A polarizing plate having a biaxially stretched cellulose
triacetate (CTA) film in combination with the optical film of the
present invention is preferred for applications to a VA mode liquid
crystal cell. A biaxially stretched CTA film is preferably produced
by the processes disclosed in JP-A-2001-249223 and
JP-A-2003-170492.
[0205] The OCB mode liquid crystal cell is a liquid crystal cell in
which rod-like liquid crystal molecules are oriented in
substantially opposite directions (symmetrically) in the upper and
lower parts of the cell (bend orientation) in an on state, which is
disclosed in U.S. Pat. Nos. 4,583,825 and 5,410,422. Because of the
bend orientation in which the rod-like liquid crystal molecules are
oriented symmetrically about the middle of the cell thickness, the
cell has an optical self compensation function, for which the cell
of this type is called an optically compensated bend (OCB) mode
cell. A bend mode liquid crystal cell is characterized by a short
response time.
[0206] The ECB mode liquid crystal cell is a liquid crystal cell in
which rod-like liquid crystal molecules are oriented substantially
horizontally in an off state and which is used mostly in color TFT
liquid crystal display devices. There is an abundant literature on
the ECB mode liquid crystal cells, including EL, PDP, LCD Displays,
Toray Research Center, 2001.
[0207] For applications to TN-mode or IPS-mode liquid crystal
displays in particular, it is preferred for the polarizing plate of
the invention to have an optically compensation film having a
viewing angle widening effect disposed as one of the protective
films (the other protective film is the antireflection film of the
invention) as proposed in JP-A-2001-100043. Such a layer
configuration produces both antireflection effect and viewing angle
widening effect with the thickness of a single polarizing
plate.
EXAMPLES
[0208] The present invention will now be illustrated in greater
detail with reference to Examples, but it should be understood that
the invention is not construed as being limited thereto. Unless
otherwise noted, all the parts, and percents are by weight.
Example 1
Stabilization of Inorganic Oxide Particles
[0209] 1) Preparation of Dispersion A-1
[0210] Thirty parts of acryloyloxypropyltrimethoxysilane (M-1) and
1.5 parts of di(isopropoxy)(ethyl acetoacetato)aluminum were mixed
into 333 parts of silica sol IPA-ST-L (silica sol in isopropyl
alcohol, available from Nissan Chemical Industries, Ltd.; average
particle size: 45 nm; silica concentration: 30%), and 9 parts of
ion exchanged water was added thereto. The mixture was allowed to
react at 60.degree. C. for 8 hours, followed by cooling to room
temperature. To the mixture was added 1.8 parts of acetylacetone to
give dispersion A-1.
[0211] 2) Preparation of Dispersion B-1
[0212] The same procedure as in (1) above was repeated, except for
replacing IPA-ST-L with Methanol Silica Sol (silica sol in
methanol, available from Nissan Chemical; average particle size: 12
nm; silica concentration: 30%) to obtain dispersion B-1.
[0213] 3) Preparation of Dispersion C-1
[0214] The same procedure as in (1) above was repeated, except for
replacing IPA-ST-L with 500 parts of hollow silica sol CS6-IPA
(hollow silica sol in isopropyl alcohol available from Catalysts
& Chemicals Industries Co., Ltd.; average particle size: 60 nm;
shell thickness: 10 nm; silica concentration: 20%; refractive index
(as a particle): 1.31) to obtain dispersion C-1.
[0215] 4) Preparation of Dispersion D-1
[0216] Dispersion D-1 was prepared in the same manner as in (1)
above, except for replacing IPA-ST-L with zirconium oxide sol in
methyl ethyl ketone (available from Sumitomo Osaka Cement Co.,
Ltd.; average particle size: 10 nm; zirconium oxide-concentration:
30%).
[0217] 5) Preparation of Other Dispersions
[0218] Dispersions A-2 through 9, B-2 through 6, C-2 through 5, and
D-2 through 4 were prepared in the same manner as for dispersions
A-1, B-1, C-1, and D-1, respectively, except for changing the
compound of formula (I) and/or the acid catalyst or the metal
chelate compound as shown in Table 1 below.
[0219] Each of the resulting dispersions was evaluated as follows
immediately after the preparation and after storage at 40.degree.
C. for 2 weeks. The results obtained are shown in Table 1.
[0220] i) Generation of Foreign Matter
[0221] A 10 ml portion of the dispersion was put into a 10 mm
diameter test tube, inspected for any foreign matter with the naked
eye, and rated as follows.
[0222] A: No foreign matter is observed.
[0223] B: Foreign matter of about 50 .mu.m is slightly
observed.
[0224] C: Foreign matter greater than 500 .mu.m is obviously
observed.
[0225] D: Foreign matter greater than 500 .mu.m and an aggregated
precipitate are obviously observed.
[0226] ii) Change in Viscosity
[0227] The viscosity of the dispersion was measured with a
vibration type viscometer at 25.degree. C.
2 TABLE 1 Foreign Matter Viscosity (mPa .multidot. s) Inorganic
Acid Catalyst Immed. 2 wk Immed. 2 wk Dis- Oxide Compound (I) or
Metal Chelate Compound after at after at persion Particles Kind
Amount* Kind Amount* Prepn. 40.degree. C. Prepn. 40.degree. C.
Remark A-1 45 nm M-1 30 di(isopropoxy)(ethyl 1.5 A A 7 10 invention
silica acetoacetato)aluminum A-2 45 nm " 15 di(isopropoxy)(ethyl
1.5 A A 7 10 invention silica acetoacetato)aluminum A-3 45 nm " 5
di(isopropoxy)(ethyl 1.5 A A 7 11 invention silica
acetoacetato)aluminum A-4 45 nm " 30 none 0.0 A C 10 25 comparison
silica A-5 45 nm none 0 none 0.0 C D 15 30 comparison silica A-6 45
nm M-2 30 di(isopropoxy)(ethyl 1.5 A A 7 11 invention silica
acetoacetato)aluminum A-7 45 nm M-25 30 di(isopropoxy)(ethyl 1.5 A
A 7 12 invention silica acetoacetato)aluminum A-8 45 nm M-1 30
oxalic acid 10.0 A A 7 12 invention silica A-9 45 nm " 30 malonic
acid 10.0 A A 7 12 invention silica B-1 12 nm " 40
di(isopropoxy)(ethyl 2.0 A A 5 7 invention silica
acetoacetato)aluminum B-2 12 nm M-2 40 di(isopropoxy)(ethyl 2.0 A A
5 8 invention silica acetoacetato)aluminum B-3 12 nm " 40 none 0.0
B C 10 30 comparison silica B-4 12 nm none 0 none 0.0 C D 17 40
comparison silica B-5 12 nm M-25 40 di(isopropoxy)(ethyl 2.0 A A 5
8 invention silica acetoacetato)aluminum B-6 12 nm M-1 40 oxalic
acid 10.0 A A 5 8 invention silica C-1 60 nm M-1 30
di(isopropoxy)(ethyl 1.5 A A 7 10 invention hollow silica
acetoacetato)aluminum C-2 60 nm " 30 none 0.0 A C 8 25 comparison
hollow silica C-3 60 nm none 0 none 0.0 C D 15 35 comparison hollow
silica C-4 60 nm M-2 30 di(isopropoxy)(ethyl 1.5 A A 7 10 invention
hollow silica acetoacetato)aluminum C-5 60 nm M-25 30
di(isopropoxy)(ethyl 1.5 A A 7 11 invention hollow silica
acetoacetato)aluminum D-1 10 nm M-1 20 di(isopropoxy)(ethyl 1.5 A A
4 6 invention zirconium acetoacetato)aluminum oxide D-2 10 nm " 20
none 0.0 B C 5 20 comparison zirconium oxide D-3 10 nm none 0 none
0.0 B C 7 25 comparison zirconium oxide D-4 10 nm M-2 20
di(isopropoxy)(ethyl 1.5 A A 4 6 invention zirconium
acetoacetato)aluminum oxide Note: *parts per 100 parts by weight of
the solid content of the inorganic oxide particles
[0228] The following observations are drawn from the results in
Table 1. The dispersions of inorganic oxide particles having been
treated with (a) the compound of formula (I) and (b) the acid
catalyst and/or the metal chelate compound suffer from less foreign
matter generation and less increase in viscosity even when stored
in high temperature, proving to be stable. In particular, those
dispersions prepared using the metal chelate compound exhibit
excellent stability, undergoing little change in viscosity with
time.
[0229] In addition, a dispersion was prepared in the same manner as
for dispersion C-1, except for replacing the
di(isopropoxy)acetoacetatoalumin- um with di(n-butoxy)bis(ethyl
acetato)zirconium, and a dispersion was prepared in the same manner
as for dispersion D4, except for replacing the
di(isopropoxy)acetoacetatoaluminum with di(isopropoxy)bis(ethyl
acetato)titanium. The resulting dispersions were evaluated in the
same manner as described above. As a result, the dispersions
prepared by using a zirconium or titanium chelate compound also
exhibited excellent stability with reduced change in viscosity with
time.
Example 2
[0230] 1) Preparation of Dispersion A2-1 by solvent replacement
[0231] Five hundred grams of dispersion A-1 of Example 1 was
subjected to solvent replacement by distillation under a reduced
pressure of 150 Torr while adding methyl isobutyl ketone to the
dispersion at such a feed rate as to maintain the silica content of
the dispersion constant. The residual isopropyl alcohol in the
resulting dispersion (designated dispersion A2-1) was found to be
1.0% or less by gas chromatography. No foreign matter was observed.
When diluted with methyl isobutyl ketone to a solid content of 30%,
the dispersion had a viscosity of 3 mPa.multidot.s at 25.degree.
C.
[0232] 2) Preparation of Dispersion B2-2 by Solvent Replacement
[0233] Five hundred grams of dispersion B-2 of Example 1 was
subjected to solvent replacement by distillation under a reduced
pressure of 150 Torr while adding methyl ethyl ketone to the
dispersion at such a feed rate as to maintain the silica content of
the dispersion constant. The residual methanol in the resulting
dispersion (designated dispersion B2-2) was found to be 1.0% or
less by gas chromatography. No foreign matter was observed. When
diluted with methyl ethyl ketone to a solid content of 30%, the
dispersion had a viscosity of 3 mPa.multidot.s at 25.degree. C.
[0234] 3) Preparation of Dispersion C2-1 by Solvent Replacement
[0235] Five hundred grams of dispersion C-1 of Example 1 was
subjected to solvent replacement by distillation under a reduced
pressure of 150 Torr while adding methyl isobutyl ketone to the
dispersion at such a feed rate as to maintain the silica content of
the dispersion constant. The residual isopropyl alcohol in the
resulting dispersion (designated dispersion C2-1) was found to be
1.0% or less by gas chromatography. No foreign matter was observed.
When diluted with methyl isobutyl ketone to a solid content of 20%,
the dispersion had a viscosity of 2 mPa.multidot.s at 25.degree.
C.
Example 3
[0236] 1) Preparation of Coating Composition for Hard Coat
Layer
3 Trimethylolpropane triacetate (Viscoat 750.0 parts #295, from
Nippon Kayaku Co., Ltd.) Polyglycidyl methacrylate (weight 270.0
parts average molecular weight: 15000) Methyl ethyl ketone 730.0
parts Cyclohexanone 500.0 parts Photo polymerization initiator 50.0
parts (Irgacure 184, from Ciba-Geigy Japan Ltd.)
[0237] The above components were agitated in a mixing tank and
filtered through a polypropylene filter having an opening size of
0.4 .mu.m to give a coating composition for hard coat layer.
[0238] 2) Preparation of Fine Titanium Dioxide Dispersion
[0239] MPT-129C, fine particles of cobalt-containing titanium
dioxide particles having been surface treated with aluminum
hydroxide and zirconium hydroxide, available from Ishihara Sangyo
Kaisha, Ltd., was used. The particles had a
TiO.sub.2:Co.sub.3O.sub.4:Al.sub.2O.sub.3:ZrO.s- ub.2 ratio of
90.5:3.0:4.0:0.5 by weight.
[0240] The titanium dioxide particles (257.1 parts) were dispersed
in 701.8 parts of cyclohexanone using 41.1 parts of a dispersant
shown below by use of a Dynomill to prepare a titanium dioxide
dispersion having a weight average particle size of 70 nm.
Dispersant: 42
[0241] 3) Preparation of Coating Composition for Middle Refractive
Layer
4 Titanium dioxide dispersion prepared 99.1 parts in (2) above
Mixture of dipentaerythritol 68.0 parts pentaacrylate and
dipentaerythritol hexaacrylate (hereinafter referred to as DPHA)
Photo polymerization initiator 3.6 parts (Irgacure 907, from
Ciba-Geigy Japan Ltd.) Photo sensitizer (Kayacure DETX, 1.2 parts
from Nippon Kayaku Co., Ltd.) Methyl ethyl ketone 279.6 parts
Cyclohexanone 1049.0 parts
[0242] The above components were thoroughly mixed up by agitation
and filtered through a polypropylene filter having an opening size
of 0.4 .mu.m to prepare a coating composition for middle refractive
layer.
[0243] 4) Preparation of Coating Composition for High Refractive
Layer
5 Titanium dioxide dispersion 469.8 parts prepared in (2) above
DPHA (from Nippon Kayaku Co., Ltd.) 40.0 parts Photo polymerization
initiator 3.3 parts (Irgacure 907, from Ciba-Geigy Japan Ltd.)
Photo sensitizer (Kayacure DETX, 1.1 parts from Nippon Kayaku Co.,
Ltd.) Methyl ethyl ketone 526.2 parts Cyclohexanone 459.6 parts
[0244] The above components were mixed up by agitation and filtered
through a polypropylene filter having an opening size of 0.4 .mu.m
to prepare a coating composition for high refractive layer.
[0245] 5) Preparation of Coating Composition A for Low Refractive
Layer
6 Fluoropolymer P-1 shown below 74.4 parts methacrylate end
group-containing 3 parts silicone resin X-22-164C (from Shin-Etsu
Chemical Co., Ltd.) Photo radical generator Irgacure 3 parts 907
(from Ciba-Geigy Japan Ltd.) Photo sensitizer Kayacure DETX 1 part
(from Nippon Kayaku Co., Ltd.) DPHA (from Nippon Kayaku) 18.6 parts
Methyl isobutyl ketone 200 parts
[0246] In methyl isobutyl ketone were dissolved the rest of the
components listed above. The solution was diluted with methyl ethyl
ketone to prepare coating composition A having a solids content of
7%.
[0247] Fluoropolymer P-1: 43
[0248] (50:50 is by mole)
[0249] Fluoropolymer P-1 was synthesized as follows. In a 100 ml
autoclave equipped with a stainless steel stirrer were put 40 ml of
ethyl acetate, 14.7 g of hydroxyethyl vinyl ether, and 0.55 g of
dilauroyl peroxide. After the autoclave was purged with nitrogen,
25 g of hexafluoropropylene was introduced into the autoclave,
followed by heating the mixture up to 65.degree. C. The inner
pressure was 5.4 kg/cm.sup.2 when the temperature reached
65.degree. C. The reaction was continued at that temperature for 8
hours. When the inner pressure dropped to 3.2 kg/cm.sup.2, heating
was stopped, and the reaction mixture was allowed to cool. When the
inner temperature dropped to ambient temperature, the unreacted
monomers were driven out, and the autoclave was opened to take out
the reaction mixture, which was poured into a large excess of
hexane for re-recipitation. The solvent was removed by decantation.
The thus collected polymer was dissolved in a small amount of ethyl
acetate and re-precipitated twice from hexane to completely remove
any residual monomers. The precipitate was dried to yield 28 g of
the polymer. A 20 g portion of the polymer was dissolved in 100 ml
of N,N-dimethylacetamide, and 11.4 g of acryl chloride was added to
the solution dropwise while cooling with ice. After the dropwise
addition, the mixture was stirred at room temperature for 10 hours.
Ethyl acetate was added to the reaction mixture, followed by
washing with water. The organic layer was extracted and
concentrated. The resulting polymer was re-precipitated with hexane
to give 19 g of fluoropolymer P-1. Fluoropolymer P-1 had a
refractive index of 1.421.
[0250] 6) Preparation of Antireflection Film 301
[0251] The coating composition for hard coat layer was applied to a
80 .mu.m thick cellulose triacetate base film (TD-80UF, available
from Fuji Photo Film Co., Ltd.) with a gravure coater and dried at
100.degree. C. The coating layer was irradiated with ultraviolet
light at an irradiance of 400 mW/cm.sup.2 and a dose of 300
mJ/cm.sup.2 using a 160 W/cm air-cooled metal halide lamp (supplied
by Eyegraphics Co., Ltd.) while purging with nitrogen to reduce the
oxygen concentration of the atmosphere to 1.0% by volume or lower.
The coating layer was thus cured to form an 8 .mu.m thick hard coat
layer.
[0252] The coating composition for middle refractive layer, the
coating composition for high refractive layer, and the coating
composition A for low refractive layer were continuously applied in
that order onto the hard coat layer on a single web coating line
having three work stations for gravure coating.
[0253] The coating film for the middle refractive layer was dried
at 90.degree. C. for 30 seconds and then cured by irradiation with
ultraviolet light at an irradiance of 400 mW/cm.sup.2 and a dose of
400 mJ/cm.sup.2 using a 180 W/cm air-cooled metal halide lamp (from
Eyegraphics Co., Ltd.) while purging with nitrogen to reduce the
oxygen concentration of the atmosphere to, 1.0% by volume or lower.
The resulting middle refractive layer had a thickness of 67 nm and
a refractive index of 1.630.
[0254] The coating film for the high refractive layer was dried at
90.degree. C. for 30 seconds and then cured by irradiation with
ultraviolet light at an irradiance of 600 mW/cm.sup.2 and a dose of
400 mJ/cm.sup.2 using a 240 W/cm air-cooled metal halide lamp (from
Eyegraphics Co., Ltd.) while purging with nitrogen to reduce the
oxygen concentration of the atmosphere to 1.0% by volume or lower.
The resulting high refractive layer had a thickness of 107 nm and a
refractive index of 1.905.
[0255] The coating film for the low refractive layer was dried at
90.degree. C. for 30 seconds and then cured by irradiation with
ultraviolet light at an irradiance of 600 mW/cm.sup.2 and a dose of
600 mJ/cm.sup.2 using a 240 W/cm air-cooled metal halide lamp (from
Eyegraphics Co., Ltd.) while purging with nitrogen to reduce the
oxygen concentration of the atmosphere to 1.0% by volume or lower.
The resulting low refractive layer had a thickness of 85 nm and a
refractive index of 1.458.
[0256] 7) Preparation of Antireflection Film 302
[0257] Antireflection film 302 was prepared in the same manner as
for antireflection film 301, except that the low refractive layer
was formed of coating composition B described below in place of the
coating composition A.
[0258] 7-1) Preparation of Sol (a)
[0259] In a reactor equipped with a stirrer and a reflux condenser
were put 120 parts of methyl ethyl ketone, 100 parts of M-1
(acryloyloxypropyltrimethoxysilane) (KBM-5103, from Shin-Etsu
Chemical Co., Ltd.), and 3 parts of diisopropoxy(ethyl
acetoacetato)aluminum and mixed up by stirring. Thirty parts of
ion-exchanged water was added thereto, and the mixture was allowed
to react at 60.degree. C. for 4 hours, followed by cooling to room
temperature to obtain sol (a). The weight average molecular weight
of the sol particles was 1600. Hundred percent of the oligomeric
and polymeric components of the product had molecular weights
between 1000 and 20,000. The gas chromatography of sol (a) revealed
no residue of the starting material M-1.
[0260] 7-2) Preparation of Coating Composition B for Low Refractive
Layer
[0261] In 200 parts of methyl isobutyl ketone were dissolved 51
parts of fluoropolymer P-1 used in coating composition A for low
refractive layer, 3 parts of the methacrylate end group-containing
silicone resin X-22-164C (from Shin-Etsu Chemical Co., Ltd.), 3
parts of a photo radical generator Irgacure 907 (from Ciba-Geigy
Japan Ltd.), 1 part of a photo sensitizer Kayacure DETX (from
Nippon Kayaku Co., Ltd.), and 13 parts of DPHA (from Nippon
Kayaku). To the solution were added 22.5 parts of sol (a) prepared
in (7-1) above (solid content after solvent vaporization: 9 parts)
and 111 parts of dispersion A-1 prepared in Example 1 (silica solid
content: 20 parts). The mixture was diluted with methyl ethyl
ketone to a total solids content of 7% to obtain coating
composition B.
[0262] Antireflection film 302 was prepared in the same manner as
for antireflection film 301, except for using composition B to form
the low refractive layer having a thickness of 85 nm.
[0263] 8) Preparation of Antireflection Film 312
[0264] Antireflection film 312 was prepared in the same manner as
for antireflection film 302, except for using dispersion C-1
prepared in Example 1 in place of dispersion A-1, to form the low
refractive layer having a thickness of 85 nm and a refractive index
of 1.44.
[0265] 9) Preparation of antireflection film 318
[0266] Antireflection film 318 was prepared in the same manner as
for antireflection film 301, except for using coating composition C
prepared as follows in place of coating composition A, to form the
low refractive layer having a thickness of 85 nm and a refractive
index of 1.44.
[0267] Preparation of Coating Composition C for Low Refractive
Layer
[0268] In 200 parts of methyl isobutyl ketone were dissolved 44
parts of DPHA (from Nippon Kayaku Co., Ltd.), 3 parts of a
methacrylate end group-containing silicone resin X-22-164C (from
Shin-Etsu Chemical Co., Ltd.), 2.5 parts of a photo radical
initiator Irgacure 907 (from Ciba-Geigy Japan Ltd.), and 0.5 parts
of a photo sensitizer Kayacure DETX (from Nippon Kayaku). To the
solution were added 45 parts of sol (a) prepared in (7-1) above
(solid content after solvent vaporization: 18 parts) and 222 parts
of dispersion C-1 prepared in Example 1 (silica solid content: 40
parts). The mixture was diluted with methyl ethyl ketone to a total
solids content of 7% to obtain coating composition C.
[0269] 10) Preparation of Antireflection Film 324
[0270] Antireflection film 324 was prepared in the same manner as
for antireflection film 301, except that the low refractive layer
was formed as follows.
[0271] Preparation of Coating Composition D for Low Refractive
Layer
[0272] A hundred parts of Opstar JTA113 (heat crosslinking
fluoropolymer in methyl ethyl ketone, available from JSR Corp.;
solid content: 6%) and 3 parts of cyclohexanone were mixed to
prepare coating composition D for low refractive layer.
[0273] Antireflection film 324 was prepared in the same manner as
for antireflection film 301 by using coating composition D to form
an 85 nm thick low refractive layer. The coating layer of coating
composition D was dried at 120.degree. C. for 12 minutes and cured
by irradiation with ultraviolet light at an irradiance of 120
mW/cm.sup.2 and a dose of 120 mJ/cM.sup.2 using a 240 W/cm
air-cooled metal halide lamp (from Eyegraphics Co., Ltd.) while
purging with nitrogen to reduce the oxygen concentration of the
atmosphere to 1.0% by volume or lower.
[0274] 11) Preparation of Antireflection Film 325
[0275] Antireflection film 325 was prepared in the same manner as
for antireflection film 324, except for using coating composition B
prepared as follows to form the low refractive layer having a
thickness of 85 nm.
[0276] Preparation of Coating Composition E for Low Refractive
Layer
[0277] Seventy parts of Opstar JTS113 (heat crosslinking
fluoropolymer in methyl ethyl ketone, available-from JSR Corp.;
solid content: 6%), 9.9 parts of dispersion C-1 prepared in Example
1 (silica solid content; 1.8 parts), 2.0 parts of sol (a) (solid
content: 0.81 parts), and 2.4 parts of cyclohexane were mixed up to
prepare coating composition E for low refractive layer.
[0278] 12) Preparation of Other Samples
[0279] Antireflection films 303 to 317, 319 to 323, and 326 to 330
were prepared in the same manner as for antireflection films 302,
318, and 325, respectively, except that the inorganic oxide
dispersion of the coating composition for low refractive layer was
changed as shown in Table 2 below (the main binder was not
changed).
[0280] 13) Evaluation of Antireflection Films
[0281] The resulting antireflection films (sample Nos. 301 through
330) were evaluated as follows.
[0282] i) Haze
[0283] A haze was compared between a sample the low refractive
layer of which was formed using the coating composition immediately
after the preparation and a sample the low refractive layer of
which was formed using the same coating composition but after
storage at 40.degree. C. for 48 hours. Haze measurement was made
with a hazemeter 1001 DP supplied by Nippon Denshoku Industries
Co., Ltd.
[0284] ii) Steel wool scratch resistance (SW strength)
[0285] Scratch resistance of the film was evaluated using a rubbing
tester having steel wool (#0000, from Nippon Steel Wool KK) wrapped
around and fixed to its friction element (1 cm by 1 cm) with a
band. The friction element was placed in contact with the coated
side of the film with a contact area of 1 cm by 1 cm and moved back
and forth 10 times over a stroke of 13 cm at a speed of 13 cm/sec
with an applied force of 500 g/cm.sup.2. The measurement was
carried out in an atmosphere of 25.degree. C. and 60% RH. After the
rubbing test, oily black ink was applied to the reverse side of the
film, and the rubbed surface was observed with naked eye in
reflected light. The scratch resistance (SW strength) was rated
based on the following standard.
[0286] AA: Very careful examination reveals no scratches.
[0287] A: Very careful examination reveals barely visible
scratches.
[0288] No problem for practical use.
[0289] B: A shallow scratch is observed by careful examination No
problem for practical use.
[0290] C: A shallow scratch is observed.
[0291] D: A scratch is observed.
[0292] E: The film has an obvious scratch.
[0293] F: The film has scratches all over its surface.
7 TABLE 2 Haze Inorganic Acid Catalyst Immed. 48 hrs Sample Main
Dis- Oxide Compound (I) or Metal Chelate Compound After at SW No.
Binder persion Particles Kind Amount* Kind Amount* Prepn.
40.degree. C. Strength Remark 301 none none none 0 none 0 0.3 0.3 F
comparison 302 same as A-1 45 nm M-1 30 di(isopropoxy)(ethyl 1.5
0.3 0.4 AA invention in 301 silica acetoacetato)aluminum 303 same
as A-2 45 nm " 15 di(isopropoxy)(ethyl 1.5 0.3 0.4 A invention in
301 silica acetoacetato)aluminum 304 same as A-3 45 nm " 5
di(isopropoxy)(ethyl 1.5 0.3 0.5 B invention in 301 silica
acetoacetato)aluminum 305 same as A-4 45 nm " 30 none 0.0 0.7 1 D
comparison in 301 silica 306 same as A-5 45 nm none 0 none 0.0 2 3
F comparison in 301 silica 307 same as A-6 45 nm M-2 30
di(isopropoxy)(ethyl 1.5 0.3 0.4 A invention in 301 silica
acetoacetato)aluminum 308 same as A-7 45 nm M-25 30
di(isopropoxy)(ethyl 1.5 0.3 0.5 A invention in 301 silica
acetoacetato)aluminum 309 same as A-8 45 nm M-1 30 oxalic acid 10.0
0.3 0.5 A invention in 301 silica 310 same as A-9 45 nm " 30
malonic acid 10.0 0.3 0.5 A invention in 301 silica 311 same as
A2-1 45 nm " 30 di(isopropoxy)(ethyl 1.5 0.3 0.3 AA invention in
301 silica acetoacetato)aluminum 312 same as C-1 60 nm M-1 30
di(isopropoxy)(ethyl 1.5 0.3 0.4 AA invention in 301 hollow
acetoacetato)aluminum silica 313 same as C-2 60 nm " 30 none 0.0
0.7 1 D comparison in 301 hollow silica 314 same as C-3 60 nm none
0 none 0.0 2.5 3.5 F comparison in 301 hollow silica 315 same as
C-4 60 nm M-2 30 di(isopropoxy)(ethyl 1.5 0.3 0.4 A invention in
301 hollow acetoacetato)aluminum silica 316 same as C-5 60 nm M-25
30 di(isopropoxy)(ethyl 1.5 0.3 0.5 A invention in 301 hollow
acetoacetato)aluminum silica 317 same as C2-1 60 nm M-1 30
di(isopropoxy)(ethyl 1.5 0.3 0.3 AA invention in 301 hollow
acetoacetato)aluminum silica 318 C-1 60 nm M-1 30
diisopopoxy-aluminum 1.5 0.3 0.4 AA invention hollow ethyl acetate
silica 319 same as C-2 60 nm " 30 none 0.0 0.6 1 C comparison in
318 hollow silica 320 same as C-3 60 nm none 0 none 0.0 2.2 3.3 E
comparison in 318 hollow silica 321 same as C-4 60 nm M-2 30
di(isopropoxy)(ethyl 1.5 0.3 0.4 AA invention in 318 hollow
acetoacetato)aluminum silica 322 same as C-5 60 nm M-25 30
di(isopropoxy)(ethyl 1.5 0.3 0.5 A invention in 318 hollow
acetoacetato)aluminum silica 323 same as C2-1 60 nm M-1 30
di(isopropoxy)(ethyl 1.5 0.3 0.3 AA invention in 318 hollow
acetoacetato)aluminum silica 324 none none none 0 none 0.0 0.3 0.3
F comparison 325 same as C-1 60 nm M-1 30 di(isopropoxy)(ethyl 1.5
0.3 0.4 A invention in 324 hollow acetoacetato)aluminum silica 326
same as C-2 60 nm " 30 none 0.0 0.8 1.5 D comparison in 324 hollow
silica 327 same as C-3 60 nm none 0 none 0.0 2.7 3.8 F comparison
in 324 hollow silica 328 same as C-4 60 nm M-2 30
di(isopropoxy)(ethyl 1.5 0.3 0.4 A invention in 324 hollow
acetoacetato)aluminum silica 329 same as C-5 60 nm M-25 30
di(isopropoxy)(ethyl 1.5 0.3 0.4 B invention in 324 hollow
acetoacetato)aluminum silica 330 same as C2-1 60 nm M-1 30
di(isopropoxy)(ethyl 1.5 0.3 0.3 AA invention in 324 hollow
acetoacetato)aluminum silica Note: *parts per 100 parts by weight
of the inorganic oxide particle solid content
[0294] The following observations are drawn from the results in
Table 2. Coating layers formed by using the specific inorganic
oxide dispersion of the present invention undergo little increase
in haze and have improved film strength. Samples prepared using a
coating composition the main binder of which is photo curable
(sample Nos. 302 to 304, 307 to 312, 315 to 318, 321 to 323, 325,
and 328 to 330) are excellent in film strength. Furthermore,
samples 311, 317, 323, and 330, which are prepared using the
coating composition containing the dispersion having been subjected
to solvent replacement in Example 2 after storage, have a low haze,
proving the superiority of the dispersions having been subjected to
solvent replacement in stability when formulated into a coating
composition.
Example 4
[0295] Antireflection films were prepared in the same manner as in
Example 3, except for replacing the acrylate group as a
polymerizable group of fluoropolymer P-1 used in coating
composition A or B with a methacrylate group. The resulting samples
were evaluated in the same manner as in Example 3. The results of
evaluation were practically equal to those obtained in Example 3,
except that the steel wool scratch resistance was slightly
inferior.
Example 5
[0296] An 80 .mu.m thick cellulose triacetate film (TAC-TD 80U,
available from Fuji Photo Film Co., Ltd.) was immersed in a 1.5
mol/l NaOH aqueous solution at 55.degree. C. for 2 minutes and
washed with water to prepare a protective film with its both sides
saponified.
[0297] Each of the antireflection films prepared in Example 3
according to the invention was treated to have its cellulose
triacetate base film saponified.
[0298] The protective film and the saponified base film side of the
antireflection film were stuck to each side of a polarizing film to
prepare a polarizing plate. The polarizing film was prepared by
impregnating a polyvinyl alcohol film with iodine followed by
stretching.
[0299] The polarizing plate on the front side of a transmissive TN
mode LCD monitor (having D-BEF (a polarized light separation film
having a polarized light selecting layer, available from Sumitomo
3M Co., Ltd.) disposed between the backlight and the liquid crystal
cell) on a notebook computer was replaced with the resulting
polarizing plate with its antireflection layer side out. The thus
altered LCD monitor exhibited very high display quality with
markedly reduced reflection of ambient light. In particular, the
antireflection films using the hollow silica particles having a
refractive index of 1.31 in the low refractive layer (sample Nos.
312, 315, and 316) provided display monitors having high visibility
with little reflection of ambient light.
Example 6
[0300] 1) Preparation of Coating Composition for Hard Coat
Layer
8 Micture of pentaerythritol triacrylate and pentaerythritol
tetraacrylate (available from 50.0 g Nippon Kayaku Co., Ltd. Photo
polymerization initiator (Irgacure 184, from Ciba Specialties
Chemicals Corp.) 2.0 g Crosslinked polystyrene beads (SX-350, from
Soken Chemical & Engineering Co., 1.5 g Ltd.; average particle
size: 3.5 .mu.m; refractive index: 1.60) in the form of a 30%
toluene dispersion, used after being dispersed in a homogenizer
Polytron at 10,000 rpm for 20 minutes) Crosslinked
poly(acryl/styrene) beads (from Soken Chemical & Engineering
Co., 13.9 g Ltd.; average particle size: 3.5 .mu.m; refractive
index: 1.55) in the form of a 30% toluene dispersion, used after
being dispersed in Polytron at 10,000 rpm for 20 minutes)
Fluorine-containing surface modifier (FP-132) shown below: 0.75 g
44 Acryloyloxypropyltrimeethoxysilane (KBM-5103, from Shin-Etsu
Chemical Co., 10.0 g Ltd.) Toluene 38.5 g
[0301] The above components were mixed up and filtered through a
polypropylene filter having an opening size of 30 .mu.m to give a
coating composition for hard coat layer.
[0302] 2) Preparation of Multilayer Antireflection Film
[0303] A 80 .mu.m thick cellulose triacetate base film (TAC-TD80U
from Fuji Photo Film) was continuously fed at a speed of 30 m/min,
coated with the above-prepared coating composition for hard coat
layer by means of a combination of a microgravure roll and a doctor
blade. The microgravure roll had a diameter of 50 mm and a gravure
pattern of 180 lines/inch with a cell depth of 40 .mu.m and was
rotated at a speed of 30 rpm. The applied coating layer was dried
at 60.degree. C. for 150 seconds and cured by irradiation with UV
light at an irradiance of 400 mW/cm.sup.2 and a dose of 250
mJ/cm.sup.2 using a 160 W/cm air-cooled metal halide lamp (supplied
by Eyegraphics Co., Ltd.) while purging with nitrogen to reduce the
oxygen concentration of the atmosphere to 1.0% by volume or lower.
The coating layer was thus cured to form a 6 .mu.m thick hard coat
layer. The coated film was taken up. The hard coat layer had a
center-line average roughness Ra of 0.18 .mu.m, a ten point height
Rz of 1.40 .mu.m, and a haze of 35%.
[0304] A low refractive layer was formed on the hard coat layer
using each of the formulations used in Examples 3 and 4, and the
resulting antireflective film was evaluated in the same manner as
in Example 3. The results showed that the antireflection films
according to the present invention have high steel wool scratch
resistance.
Example 7
[0305] Antireflection films were prepared in the same manner as in
Examples 3 and 6, except that a slot die coating technique was used
in place of the gravure coating. As a result, it was confirmed that
the antireflection films of the present invention exhibit excellent
coating surface conditions and high scratch resistance as well as
low refractive indices.
Example 8
[0306] Each of the antireflection films prepared in Examples 3 and
6 in accordance with the present invention was stuck to the front
side of an organic ELD via a pressure sensitive adhesive. The
display exhibited excellent visibility with suppressed reflection
on its glass face plate.
Example 9
Stabilization of Inorganic Oxide Particles
[0307] 1) Preparation of Dispersion a-1
[0308] Thirty parts of tridecafluorooctyltrimethoxysilane (A-1) and
1.5 parts of di(isopropoxy)(ethyl acetoacetate)aluminum were mixed
into 333 parts of silica sol (silica sol in isopropyl alcohol,
IPA-ST-L, available from Nissan Chemical Industries, Ltd.; average
particle size: 45 nm; silica concentration: 30%), and 9 parts of
ion exchanged water was added thereto. The mixture was allowed to
react at 60.degree. C. for 8 hours, followed by cooling to room
temperature. To the mixture was added 1.8 parts of acetylacetone to
give dispersion a-1.
[0309] 2) Preparation of Dispersion b-1
[0310] Thirty parts of heptadecafluorodecyltrimethoxysilane (A-3)
(TSL-8233, available from GE Toshiba Silicones) and 1.5 parts of
di(isopropoxy)(ethyl acetoacetato)aluminum were mixed into 333
parts of silica sol (Methanol Silica Sol, from Nissan Chemical;
average particle size: 12 nm; silica concentration: 30%), and 9
parts of ion exchanged water was added thereto. The mixture was
allowed to react at 60.degree. C. for 8 hours, followed by cooling
to room temperature. To the reaction mixture was added 1.8 parts of
acetylacetone to obtain dispersion b-1.
[0311] 3) Preparation of Dispersion c-1
[0312] Thirty parts of tridecafluorooctyltrimethoxysilane (A-1) and
1.5 parts of di(isopropoxy)(ethyl acetoacetato)aluminum were mixed
into 500 parts of hollow silica sol (hollow silica sol in isopropyl
alcohol, CS-60-IPA, available from Catalysts & Chemicals
Industries Co., Ltd.; average particle size: 60 nm; shell
thickness: 10 nm; silica concentration: 20%; refractive index:
1.31), and 9 parts of ion exchanged water was added thereto. The
mixture was allowed to react at 60.degree. C. for 8 hours, followed
by cooling to room temperature. To the mixture was added 1.8 parts
of acetylacetone to give dispersion c-1.
[0313] 4) Preparation of Dispersion d-1
[0314] Thirty parts of heptadecafluorodecyltrimethoxysilane (A-3)
and 1.5 parts of di(isopropoxy)(ethyl acetoacetato)aluminum were
mixed into 333 parts of zirconium oxide sol in methyl ethyl ketone
(available from Sumitomo Osaka Cement Co., Ltd.; average particle
size: 10 nm; zirconium oxide concentration: 30%), and 9 parts of
ion exchanged water was added thereto. The mixture was allowed to
react at 60.degree. C. for 8 hours, followed by cooling to room
temperature. To the mixture was added 1.8 parts of acetylacetone to
give dispersion d-1.
[0315] 5) Preparation of Other Dispersions
[0316] Dispersions a-2 through 4, b-2 through 4, C-2 through 4, and
d-2 through 4 were prepared in the same manner as for dispersions
a-1, b-1, c-1, and d-1, respectively, except for changing the
fluorine-containing action system as shown in Table 3 below.
[0317] Each of the resulting dispersions was evaluated as follows
immediately after the preparation and after storage at 40.degree.
C. for 2 weeks. The results obtained are shown in Table 3.
[0318] i) Generation of foreign matter
[0319] A 10 ml portion of the dispersion was put into a 10 mm
diameter test tube, inspected for any foreign matter with the naked
eye, and rated as follows.
[0320] A: No foreign matter is observed.
[0321] B: Foreign matter of about 50 .mu.m is slightly
observed.
[0322] C: Foreign matter greater than 500 .mu.m is obviously
observed.
[0323] D: Foreign matter greater than 500 .mu.m and an aggregated
precipitate are obviously observed.
[0324] ii) Change in viscosity
[0325] The viscosity of the dispersion was measured with a
vibration type viscometer CJV5000 (available from A & D Co.,
Ltd.) at 25.degree. C.
9 TABLE 3 Foreign Matter Viscosity (mPa .multidot. s) Inorganic
Immed. 2 wk Immed. 2 wk Dis- Oxide Compound (1) Compound (II) after
at after at persion Particles Kind Amount* Kind Amount* Prepn.
40.degree. C. Prepn. 40.degree. C. Remark a-1 45 nm silica A-1 30
-- 0 A A 7 9 invention a-2 " A-1 30 M-1 30 A A 7 10 invention a-3 "
A-1 30 M-2 60 A A 7 10 invention a-4 " -- 0 -- 0 D D 15 30
comparison b-1 12 nm silica A-3 30 -- 0 A A 7 9 invention b-2 " A-3
30 M-2 30 A A 7 11 invention b-3 " A-1 30 M-2 60 A A 7 10 invention
b-4 " -- 0 -- 0 D C 15 30 comparison c-1 60 nm A-1 30 -- 0 A A 7 9
invention hollow silica c-2 60 nm A-1 30 M-1 30 A A 7 10 invention
hollow silica c-3 60 nm A-1 30 M-2 60 A A 7 10 invention hollow
silica c-4 60 nm -- 0 -- 0 D D 15 35 comparison hollow silica d-1
10 nm A-3 30 -- 0 A A 4 6 invention zirconia d-2 10 nm A-3 30 M-1
30 A A 4 6 invention zirconia d-3 A-1 30 M-1 60 A A 4 6 invention
d-4 10 nm -- 0 -- 0 D D 7 25 comparison zirconia Note: *part per
100 parts by weight of the inorganic oxide particle solid
content
[0326] The following observations are drawn from the results in
Table 3. The dispersions of inorganic oxide particles having been
treated using the fluorine-containing silane coupling agent of
formula (1) and/or the organosilane compound of formula (II) in the
presence of the metal chelate compound suffer from less foreign
matter generation immediately after the preparation and even after
storage in high temperature and less increase in viscosity even
when stored at 40.degree. C. for two weeks, proving to be
stable.
Example 10
[0327] 1) Preparation of Sol (b)
[0328] Sol (b) was prepared in the same manner as for sol (a) of
Example 3, except that the reaction time was reduced to 2
hours.
[0329] 2) Preparation of Sol (c)
[0330] Sol (c) was prepared in the same manner as for sol (b),
except for replacing 100 parts of M-1 with 40 parts of A-1
(TSL-8257 from GE Toshiba Silicone) and 60 parts of M-1.
[0331] 3) Preparation of Dispersion c-5
[0332] Thirty parts of M-1 and 1.5 parts of di(isopropoxy)(ethyl
acetoacetato)aluminum were mixed into 500 parts of hollow silica
sol in isopropyl alcohol (CS-60-IPA, from Catalysts & Chemicals
Industries Co., Ltd.; average particle size: 60 nm; shell
thickness: 10 nm; silica concentration: 20%; refractive index:
1.31), and 9 parts of ion exchanged water was added thereto. The
mixture was allowed to react at 60.degree. C. for 8 hours, followed
by cooling to room temperature. To the mixture was added 1.8 parts
of acetylacetone to give dispersion c-5.
[0333] 4) Preparation of Dispersion c-6
[0334] Ten parts of A-1 and 1.5 parts of di(isopropoxy)(ethyl
acetoacetato)aluminum were mixed into 500 parts of hollow silica
sol in isopropyl alcohol (CS-60-IPA, from Catalysts & Chemicals
Industries Co., Ltd.; average particle size: 60 nm; shell
thickness: 10 nm; silica concentration: 20%; refractive index:
1.31), and 9 parts of ion exchanged water was added thereto. The
mixture was allowed to react at 60.degree. C. for 4 hours. Thirty
parts of M-1 was added to the reaction mixture, and the reaction
was further continued for an additional 4 hour period, followed by
cooling to room temperature. To the mixture was added 1.8 parts of
acetylacetone to obtain dispersion c-6.
[0335] 5) Preparation of Dispersion c-7
[0336] Fifteen parts of M-1 and 1.5 parts of di(isopropoxy)(ethyl
acetoacetato)aluminum were mixed into 500 parts of hollow silica
sol in isopropyl alcohol (CS-60-IPA, from Catalysts & Chemicals
Industries Co., Ltd.; average particle size: 60 nm;.shell
thickness: 10 nm; silica concentration: 20%; refractive index:
1.31), and 9 parts of ion exchanged water was added thereto. The
mixture was allowed to react at 60.degree. C. for 4 hours.
Sixty-three parts of sol (c) prepared in (2) above was added to the
reaction mixture, and the reaction was further continued for an
additional 4 hour period, followed by cooling to room temperature.
To the mixture was added 1.8 parts of acetylacetone to give
dispersion c-7.
[0337] 6) Preparation of dispersion c-8
[0338] Ten parts of A-1 and 1.5 parts of di(isopropoxy)(ethyl
acetoacetato)aluminum were mixed into 500 parts of hollow silica
sol in isopropyl alcohol (CS-60-IPA, from Catalysts & Chemicals
Industries Co., Ltd.; average particle size: 60 nm; shell
thickness: 10 nm silica concentration: 20%; refractive index:
1.31), and 9 parts of ion exchanged water was added thereto. The
mixture was allowed to react at 60.degree. C. for 4 hours.
Seventy-five parts of sol (b) prepared in (1) above was added to
the reaction mixture, and the reaction was further continued for an
additional 4 hour period, followed by cooling to room temperature.
To the mixture was added 1.8 parts of acetylacetone to give
dispersion c-8.
[0339] 7) Preparation of Dispersion c-9
[0340] Ten parts of A-1, 30 parts of M-1, and 1.5 parts of
di(isopropoxy)(ethyl acetoacetato)aluminum were mixed into 500
parts of hollow silica sol in isopropyl alcohol (CS-60-IPA, from
Catalysts & Chemicals Industries Co., Ltd.; average particle
size: 60 nm; shell thickness: 10 nm; silica concentration: 20%;
refractive index: 1.31), and 9 parts of ion exchanged water was
added thereto. The mixture was allowed to react at 60.degree. C.
for 8 hours, followed by cooling to room temperature. To the
mixture was added 1.8 parts of acetylacetone to give dispersion
c-9.
[0341] 8) Preparation of dispersion 2blank by solvent
replacement
[0342] Five hundred grams of untreated hollow silica sol in
isopropyl alcohol (CS-60-IPA, from Catalysts & Chemicals
Industries Co., Ltd.; average particle size: 60 nm; shell
thickness: 10 nm; silica concentration: 20%; refractive index:
1.31) was subjected to solvent replacement by distillation under a
reduced pressure of 39 hPa while adding cyclohexanone to the
dispersion at such a feed rate as to maintain the silica content of
the dispersion constant. No foreign matter was observed in the
resulting dispersion. When diluted with methyl isobutyl ketone to a
solid content of 20%, the dispersion had a viscosity of 3
mPa.multidot.s at 25.degree. C. The residual isopropyl alcohol in
the dispersion was found to be 0.5% or less by gas
chromatography.
[0343] 9) Preparation of Dispersion 2c-1 by Solvent Replacement
[0344] Five hundred grams of dispersion c-1 prepared in Example 9
was subjected to solvent replacement in the same manner as in (8)
above to obtain dispersion 2c-1. The viscosity of dispersion 2c-1
was 12 mPa.multidot.s at 25.degree. C.
[0345] 10) Preparation of Dispersion 2c-2 by Solvent
Replacement
[0346] Five hundred grams of dispersion c-2 prepared in Example 9
was subjected to solvent replacement in the same manner as in (8)
above to obtain dispersion 2c-2. The viscosity of dispersion 2c-2
was 13 mPa.multidot.s at 25.degree. C.
[0347] 11) Preparation of Dispersion 2c-3 by Solvent
Replacement
[0348] Five hundred grams of dispersion c-3 prepared in Example 9
was subjected to solvent replacement in the same manner as in (8)
above to obtain dispersion 2c-3. The viscosity of dispersion 2c-3
was 13 mPa.multidot.s at 25.degree. C.
[0349] 12) Preparation of Dispersion 2c-5 by Solvent
Replacement
[0350] Five hundred grams of dispersion c-5 prepared in (3) above
was subjected to solvent replacement in the same manner as in (8)
above to obtain dispersion 2c-5. The viscosity of dispersion 2c-5
was 15 mPa.multidot.s at 25.degree. C.
[0351] 13) Preparation of Dispersions 2c-6 to 2c-9 by Solvent
Replacement
[0352] Solvent replacement was carried out in the same manner as in
(8) above, except for replacing CS-60-IPA with each of dispersions
c-6 to c-9, to obtain dispersions c2-6 to c2-9.
Example 11
[0353] 1) Preparation of Antireflection Film 1101
[0354] An antireflection film 1101 was prepared in the same manner
as for sample 301 of Example 3, except that coating composition F
prepared as described blow was used in place of coating composition
A to form the low refractive layer and that curing of coating
composition F by UV irradiation was carried out in an atmosphere
with an oxygen concentration of 0.05% by volume or lower.
[0355] Preparation of Coating Composition F for Low Refractive
Layer
10 Fluoropolymer P-3 75.2 parts methacrylate end group-containing 3
parts silicone resin RMS-033 (from Gelest Inc.) Photo radical
initiator Irgacure 3 parts 907 (from Ciba-Geigy Japan Ltd.) DPHA
(from Nippon Kayaku) 18.8 parts 2-Butanone 200 parts Cyclohexanone
150 parts
[0356] In a mixture of 2-butanone and cyclohexanone were dissolved
the rest of the components listed above. The solution was diluted
with methyl ethyl ketone to prepare a coating composition F having
a solids content of 7%.
[0357] The cured low refractive layer had a thickness of 85 nm and
a refractive index of 1.458.
[0358] 2) Preparation of Antireflection Film 1102
[0359] Antireflection film 1102 was prepared in the same manner as
for antireflection film 1101, except that the low refractive layer
was formed of coating composition G described below in place of the
coating composition F.
[0360] Preparation of Coating Composition G for Low Refractive
Layer
[0361] In a mixed solvent of 200 parts of 2-butanone and 150 parts
of cyclohexanone were dissolved 30 parts of the fluoropolymer P-3,
3 parts of the methacrylate end group-containing silicone resin
RMS-033 (from Gelest Inc.), 3 parts of a photo radical generator
Irgacure 907 (from Ciba-Geigy Japan Ltd.), and 7 parts of DPHA
(from Nippon Kayalu Co., Ltd.). To the solution were added 18 parts
of sol (a) prepared in Example 3 and 150 parts of dispersion 2blank
prepared in Example 10 (silica solid content: 30 parts). The
mixture was diluted with methyl ethyl ketone to a total solids
content of 7% to obtain coating composition G.
[0362] The low refractive layer (thickness: 85 nm) of
antireflection film 1102 had a refractive index of 1.435.
[0363] 3) Preparation of Other Samples 1103 to 1107
[0364] Antireflection films 1103 through 1106 were prepared in the
same manner as for antireflection film 1102, except that the kind
of the inorganic oxide dispersion and the amount of sol (a) in the
coating composition for low refractive layer were changed as shown
in Table 4 below (the main binder was not changed). All the films
1103 to 1106 had a refractive index of about 1.435.
[0365] Antireflection film 1107 was prepared in the same manner as
antireflection film 1105, except for replacing the fluoropolymer
P-3 with DPHA. The refractive index of antireflection film 1107 as
1.44.
[0366] 4) Evaluation of Antireflection Films
[0367] The resulting antireflection films (sample Nos. 1101 through
1107) were evaluated as follows. The results obtained are shown in
Table 4.
[0368] i) Surface condition
[0369] Oily black ink was applied to the reverse side of the
antireflection film, and the surface side of the film was inspected
with the naked eye at various angles about 10 cm below a 500 W
3-wave fluorescent lamp. Unevenness looking like white haze due to
reflected light scattering was rated as follows.
[0370] A: No haze is seen even with a very careful examination.
[0371] B: A very careful examination reveals slight light
scattering.
[0372] C: A whitish haze is partly observed.
[0373] D: A whitish haze is observed all over the surface.
[0374] ii) Steel wool scratch resistance (SW strength)
[0375] Scratch resistance of the film was evaluated in the same
manner as in Example 3.
11TABLE 4 Sample Dispersion Sol (a) Surface SW No. No. (part*)
Condition Strength Remark 1101 -- -- A F comparison 1102 2blank 18
D F comparison 1103 2c-1 12 B AA invention 1104 2c-2 6 A AA
invention 1105 2c-3 0 A AA invention 1106 2c-5 12 C A invention
1107 2c-3 0 B A invention
[0376] The results in Table 4 prove that the coating film formed by
using the surface-treated hollow silica dispersion according to the
present invention is excellent in surface condition and SW
strength.
[0377] 5) Antireflection films 1108 to 1111 were prepared in the
same manner as for antireflection film 1102, except that the
inorganic oxide dispersion of coating composition G was changed as
shown in Table 5 below and that sol (a) was not used in the coating
composition (the main binder was not changed). The amount of the
tridecafluorooctyltrimethoxysilane (A-1) and/or
acryloyloxypropyltrimethoxysilane (M-1) that were present from the
start of the reaction in the preparation of the inorganic oxide
dispersion and the amount of A-1 and/or M-1 that were added in the
course of the reaction are also shown in Table 5. The resulting
films were evaluated in the same manner as described above. The
results obtained are shown in Table 5.
12TABLE 5 Initial Added Sample Dispersion Amount Amount Surface SW
No. No. A-1 M-1 A-1 M-1 Condition Strength Remark 1108 2c-6 10 --
-- 30 B AA invention 1109 2c-7 -- 15 10* 15* A AA invention 1110
2c-8 20 -- -- 30** A A invention 1111 2c-9 20 30 -- -- B A
invention Note: *The amount of A-1 or M-1 used in the preparation
of sol (c) added in the course of the reaction. **The amount of M-1
used in the preparation of sol (b) added in the course of the
reaction.
[0378] On comparing samples using the same amount of the
fluorine-containing silane coupling agent A-1 and the same amount
of the organosilane compound M-1, it can be seen that adding M-1 or
sol (b) (i.e., sol of M-1) in the course of the reaction as in
samples 1108 and 1110, respectively, tends to result in improved
surface condition and improved SW strength. It is additionally seen
that addition of sol (c) (i.e., sol of A-1 and M-1) in the course
of the reaction as in Sample 1109 also tends to result in
improvements in surface condition and SW strength.
Example 12
[0379] Antireflection films were prepared in the same manner as in
Example 11, except that the acrylate group as a polymerizable group
of the fluoropolymer (P-3) used in coating compositions F and G for
low refractive layer was replaced with a methacrylate group. The
resulting antireflection films were evaluated in the same manner as
in Example 11 to give practically the same results as in Example
11, except that the SW strength was slightly deteriorated.
Example 13
[0380] An 80 .mu.m thick cellulose triacetate film (TAC-TD 80U,
available from Fuji Photo Film Co., Ltd.) was immersed in a 1.5
mol/l NaOH aqueous solution at 55.degree. C. for 2 minutes and
washed with water to prepare a protective film with its both sides
saponified.
[0381] Each of the antireflection films prepared in Example 11
according to the invention was treated to have its cellulose
triacetate base film saponified.
[0382] The protective film and the saponified base film side of the
antireflection film were stuck to each side of a polarizing film to
prepare a polarizing plate. The polarizing film was prepared by
impregnating a polyvinyl alcohol film with iodine followed by
stretching.
[0383] The polarizing plate on the front side of a transmissive TN
mode LCD monitor (having D-BEF (a polarized light separation film
having a polarized light selecting layer, available from Sumitomo
3M Co., Ltd.) disposed between the backlight and the liquid crystal
cell) on a notebook computer was displaced with the resulting
polarizing plate with its antireflection layer side out. The thus
altered LCD monitor exhibited very high display quality with
markedly reduced reflection of ambient light. In particular, the
antireflection films using hollow silica particles having a
refractive index of 1.31 in the low refractive layer provided
display monitors having high visibility with little reflection of
ambient light.
Example 14
[0384] 1) Preparation of Coating Composition for Hard Coat
Layer
13 Mixture of pentaerythriol triacrylate and pentaerythritol
tetraacrylate (Kayarad 50.0 g PET-30, available from Nippon Kayaku
Co., Ltd.) Photo polymerization initiator (Irgacure 184, from Ciba
Specialties Chemicals Corp.) 2.0 g Crosslinked polystyrene beads
(SX-350, from Soken Chemical & Engineering Co., 1.5 g Ltd.;
average particle size: 3.5 .mu.m; refractive index: 1.60) in the
form of a 30% toluene dispersion, used after being dispersed in a
homogenizer Polytron at 10,000 rpm for 20 minutes) Crosslinked
poly(acrylate/styrene) beads (from Soken Chemical & Engineering
Co., 13.9 g Ltd.; average particle size: 3.5 .mu.m, refractive
index: 1.55) in the form of a 30% toluene dispersion, used after
being dispersed in Polytron at 10,000 rpm for 20 minutes)
Fluorine-containing surface modifier (FP-132) shown below: 0.75 g
45 Acryloyloxypropyltrimeth- oxysilane (KBM-5103, from Shin-Etsu
Chemical Co., 10.0 g Ltd.) Toluene 38.5 g
[0385] The above components were mixed up and filtered through a
polypropylene filter having an opening size of 30 .mu.m to give a
coating composition for hard coat layer.
[0386] 2) Preparation of Multilayer Antireflection Film
[0387] A 80 .mu.m thick cellulose triacetate base film (TAC-TD80U
from Fuji Photo Film) was continuously fed at a speed of 30 m/min,
coated with the coating composition for hard coat layer by means of
a combination of a microgravure roll and a doctor blade. The
microgravure roll had a diameter of 50 mm and a gravure pattern of
180 lines/inch with a cell depth of 40 .mu.m and was rotated at a
speed of 30 rpm. The applied coating layer was dried at 60.degree.
C. for 150 seconds and cured by irradiation with UV light at an
irradiance of 400 mW/cm.sup.2 and a dose of 250 mJ/cm.sup.2 using a
160 W/cm air-cooled metal halide lamp (supplied by Eyegraphics Co.,
Ltd.) while purging with nitrogen to reduce the oxygen
concentration of the atmosphere to 1.0% by volume or lower. The
coating layer was thus cured to form a 6 .mu.m thick hard coat
layer. The hard coat layer had a center-line average roughness Ra
of 0.18 .mu.m, a ten point height Rz of 1.40 .mu.m, and a haze of
35%.
[0388] A low refractive layer was formed on the hard coat layer
using each of the formulations used in Examples 11 and 12, and the
resulting antireflective film was evaluated in the same manner as
in Example 11. The results showed that the antireflection films
according to-the invention have an excellent surface condition and
high steel-wool scratch resistance.
Example 15
[0389] 1) Preparation of Coating Composition for Hard Coat
Layer
[0390] The components shown below were agitated in a mixing tank to
prepare a coating composition for hard coat layer.
14 Zirconia-containing UV curing resin 100 parts composition
(DeSolite, from JSR Corp.) DPHA (from Nippon Kayaku Co., Ltd.) 31
parts Silane coupling agent (KBM-5103, 10 parts from Shin-Etsu
Chemical Co., Ltd.) Silica particles (KE-P150, from Nippon Shokubai
8.9 parts Co., Ltd.; average particle size: 1.5 .mu.m) Crosslinked
polymethyl methacrylate particles 3.4 parts (MXS-300, from Soken
Chemical & Engineering Co., Ltd.; average particle size: 3
.mu.m) Methyl ethyl ketone 29 parts Methyl isobutyl ketone 13
parts
[0391] 2) Preparation of Multilayer Antireflection Film
[0392] A 80 .mu.m thick cellulose triacetate base film (TAC-TD80U
from Fuji Photo Film) was continuously fed at a speed of 10 m/min,
coated with the coating composition for hard coat layer by means of
a combination of a microgravure roll and a doctor blade. The
microgravure roll had a diameter of 50 mm and a gravure pattern of
135 lines/inch with a cell depth of 60 .mu.m. The applied coating
layer was dried at 60.degree. C. for 150 seconds and cured by
irradiation with UV light at an irradiance of 400 mW/cm.sup.2 and a
dose of 250 mJ/cm.sup.2 using a 160 W/cm air-cooled metal halide
lamp (supplied by Eyegraphics Co., Ltd.) while purging the
atmosphere with nitrogen and taken up. The rotating speed of the
microgravure roll was adjusted so as to give a cured hard coat
layer of 3.6 .mu.m. The hard coat layer had a center-line average
roughness Ra of 0.04 .mu.m, an Rq (the equivalent or RMS) of 0.06
.mu.m, a ten point height Rz of 0.27 .mu.m as measured with a
scanning probe microscope system SPI3800 supplied by Seiko
Instruments Inc.
[0393] A low refractive layer was formed on the hard coat layer
using each of coating compositions F and G prepared in Example 11,
and the resulting antireflective films were evaluated in the same
manner as in Example 11. The results showed that the antireflection
films according to the invention have an excellent surface
condition and high steel wool scratch resistance.
Example 16
[0394] Antireflection films were prepared and evaluated in the same
manner as in Examples 11 and 15, except that a slot die coating
system was used in place of the microgravure coating system. The
resulting films of the present invention have an excellent surface
condition, a low refractive index, and high scratch resistance.
Example 17
[0395] Each of the antireflection films prepared in Examples 11 and
15 according to the present invention was stuck to the front glass
of an organic ELD via a pressure-sensitive adhesive. The display
exhibited excellent visibility with suppressed reflection on the
glass surface.
[0396] This application is based on Japanese Patent application JP
2004-340106, filed Nov. 25, 2004, Japanese Patent application JP
2003-434144, filed Dec. 26, 2003, and Japanese Patent application
JP 2004-90450, filed Mar. 25, 2004, the entire contents of those
are hereby incorporated by reference, the same as if set forth at
length.
* * * * *