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Description  |
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DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to an optical device comprising optical parts
bonded together with an optically transparent adhesive material, an
adhesive composition for forming the same and a bonding method.
Technologies for increasing communication capacity have been acquiring
greater importance due to the spread of the Internet. Bonding technologies
used for the assembly of optical parts and optical elements used in
optical fiber communication systems require high reliability, accurate
adjustment of refractive index (for connecting optical paths), precise
position accuracy (for connecting lenses) and high heat resistance (solder
heat resistance). For the assembly of optical parts, soldering, laser
welding and an organic adhesive such as an acrylic resin or epoxy resin
have been used, or adhesives composed of organic-inorganic composite
materials prepared by a sol-gel method have been proposed. (i) Proceedings
of the 48th ECTC, pp. 1178-1185, 1998 proposes a fluorinated or
sulfur-containing epoxy adhesive and epoxy-acrylic adhesive and (ii)
Journal of Non-crystalline Solids, vol. 80, pp. 557-563, 1986 or (iii)
Intl. Congr, On Glass.S, pp. 429-436, 1986 discloses organic and inorganic
adhesives prepared by a sol-gel method. (iv) Japanese Patent No. 1829914
discloses an optical element which is produced using a sol-gel adhesive
composed of an alkoxide and a metal salt and (v) Japanese Patent No.
2786996 discloses a prism which is constructed using an adhesive composed
of a sllicate and alkoxide. Further, (vi) U.S. Pat. No. 5,991,493
discloses an optical element which is fabricated using an
organic-inorganic composite adhesive, for example, an adhesive obtained by
hydrolyzing a sol consisting of polydimethylsiloxane,
methyltriethoxysilane and phenyltrifluorosilane.
However, technologies and adhesives for bonding these optical parts involve
the following problems.
As for soldering and laser welding methods, fixed position accuracy is
unsatisfactory, or a laser light source or advanced technology is
required. Epoxy adhesives and acrylic adhesives (i) are inferior in heat
resistance of 250.degree. C. or more (solder heat resistance). Adhesives
comprising an alkoxide and a metal salt (ii to vi) have such problems that
the bonding strength of an adhesive layer is insufficient because a
cohesive failure readily occurs in the adhesive layer and that bubbles
remain by bonding together optical parts such as lenses, the adhesive
layer becomes cloudy, or sufficient adhesion cannot be obtained because an
alcohol formed by a hydrolytic reaction or water formed by a dehydration
reaction is evaporated during thermal curing.
It is an object of the present invention to provide an adhesive composition
which improves the above problems, has high adhesion strength and
excellent heat resistance, and can be used to bond optical parts together
without producing such a defect as cloudiness caused by bubbles by
reducing the generation of bubbles at the time of curing.
It is another object of the present invention to provide a method of
bonding optical parts using the adhesive composition of the present
invention.
It is still another object of the present invention to provide an optical
device comprising optical parts bonded together with the adhesive
composition of the present invention.
Other objects and advantages of the present invention will become apparent
from the following description.
According to the present invention, firstly, the above objects and
advantages of the present invention are attained by an optical device
comprising at least two optically transparent optical parts which are
bonded together with an optically transparent adhesive layer, wherein the
adhesive layer is formed from a matrix containing at least one type of
specific atoms selected from the group consisting of silicon, titanium,
zirconium, aluminum and germanium, and oxygen atoms, at least part of the
specific atoms is bonded to other specific atom(s) through a polyvalent
hydrocarbon group having 2 to 8 carbon atoms and directly bonded to at
least one monovalent hydrocarbon group selected from the group consisting
of an alkyl group, phenyl group, monovalent fluorine-containing
hydrocarbon group and monovalent sulfur-containing hydrocarbon group, and
the contents of the above specific atom, the polyvalent hydrocarbon group
and the monovalent hydrocarbon group are adjusted such that the refractive
index value of the adhesive layer approximates to the refractive index
values of the at least two optically transparent optical parts.
According to the present invention, secondly, the above objects and
advantages of the present invention are attained by an adhesive
composition for bonding optical parts together, which comprises the
following components (A), (B) and (C):
(A) organopolysiloxane having at least two alkenyl groups having 4 or less
carbon atoms bonded to silicon atoms in the molecule;
(B) organohydrogenpolysiloxane having at least two hydrogen atoms bonded to
silicone atoms in the molecule; and
(C) a platinum-based catalyst.
According to the present invention, thirdly, the above objects and
advantages of the present invention are attained by a method of bonding
optical parts together, which comprises placing an adhesive composition
containing the above components (A), (B) and (C) between at least two
optical parts to be bonded together and curing the adhesive composition.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of a first embodiment of the present invention;
FIG. 2 is a sectional view of another embodiment of the present invention;
FIG. 3 is a sectional view of still another embodiment of the present
invention;
FIG. 4 is a sectional view of a further embodiment of the present
invention;
FIG. 5 is a sectional view of a still further embodiment of the present
invention; and
FIG. 6 is a sectional view of a still further embodiment of the present
invention.
The present invention will be described in detail hereinafter. A
description is first given of the optical device.
A polyvalent hydrocarbon group having 2 to 8 carbon atoms is contained in
the adhesive layer of the optical device of the present invention. When
the number of carbon atoms of the polyvalent hydrocarbon group is too
large, the heat resistance of the adhesive layer lowers and the
hydrophobic nature of the adhesive layer increases, thereby deteriorating
the adhesion of the adhesive layer to the surface of glass or other
optical part. Therefore, the number of carbon atoms of the polyvalent
hydrocarbon group must be 8 or less, preferably 4 or less. The polyvalent
hydrocarbon group is selected from divalent to pentavalent hydrocarbon
groups. Examples of the divalent hydrocarbon group having 4 or less carbon
atoms include ethylene, trimethylene, tetramethylene, methylethylene,
ethylethylene, dimethylethylene, vinylene, propenylene, butenylene,
methylvinylene, ethylvinylene, dimethylvinylene and methylpropenylene.
Examples of the tervalent hydrocarbon group having 4 or less carbon atoms
include 1,2,3-propanetoluyl group and 1,2,4-butanetoluyl group. Examples
of the tetravalent hydrocarbon group having 4 or less carbon atoms include
1,3-propanediyl-2-ylidene group, 1,3-butanediyl-2-ylidene group and
1,4-butanediyl-2-ylidene group. Examples of the pentavalent hydrocarbon
group having 4 or less carbon atoms include 1,3-butanediyl-2,4-ylidene
group and 1,4-butanediyl-2,3-ylidene group. The hydrogen atoms of the
polyvalent hydrocarbon group having 4 or less carbon atoms may be
substituted with heavy hydrogen or elemental halogen such as fluorine,
chlorine or bromine. An adhesive layer having high transmission of light
having a communication wavelength of 1.55 .mu.m or 1.3 .mu.m can be
provided by substituting with heavy hydrogen or halogen. Out of these,
ethylene, trimethylene and tetramethylene are preferred and ethylene is
the most preferred from the viewpoints of synthesis ease and heat
resistance.
The monovalent hydrocarbon group contained in the adhesive layer of the
optical device of the present invention is selected from an alkyl group,
aryl group, monovalent fluorine-containing hydrocarbon group and
monovalent sulfur-containing hydrocarbon group. Examples of the alkyl
group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,
octadecyl and the like. Examples of the aryl group include phenyl,
methylphenyl, ethylphenyl, dimethylphenyl, trimethylphenyl, biphenyl,
naphthyl and the like. Examples of the monovalent fluorine-containing
hydrocarbon group include trifluoromethyl, pentafluoroethyl.
heptafluoropropyl, trifluoropropyl and the like. Examples of the
monovalent sulfur-containing hydrocarbon group include hydrocarbon groups
having a thiol group, sulfide group, disulfide group, polysulfide group or
sulfone group.
The hydrogen atom of these monovalent hydrocarbon groups may be substituted
with heavy hydrogen or elemental halogen such as fluorine, chlorine or
bromine. An adhesive layer having high transmission of light having a
communication wavelength of 1.55 .mu.m or 1.3 .mu.m can be provided by
substituting with heavy hydrogen or halogen. Out of these, methyl, phenyl
and trifluoromethyl are preferred from the viewpoints of synthesis ease,
heat resistance and the control of refractive index.
The adhesive layer of the optical device of the present invention is formed
from a matrix containing at least one type of specific atoms selected form
the group consisting of silicon, titanium, zirconium, aluminum and
germanium, and oxygen atoms. At least one of the specific atoms is bonded
to other specific atom(s) through a polyvalent hydrocarbon group having at
least 2 carbon atoms. At least one of the specific atoms is directly
bonded to at least one monovalent hydrocarbon group selected from the
group consisting of an alkyl group, phenyl group, monovalent
fluorine-containing hydrocarbon group and monovalent sulfur-containing
hydrocarbon group. The contents of each of the specific atoms, the
polyvalent hydrocarbon group and the monovalent hydrocarbon group are
adjusted such that the refractive index value of the adhesive layer should
approximate to the refractive index values of the at least two optically
transparent optical parts.
The adhesion strength of the adhesive layer can be increased and the
refractive index thereof can be adjusted by using at least one type of
specific atoms (may be referred to as "network forming atoms" hereinafter)
selected from the group consisting of silicon, titanium, zirconium,
aluminum and germanium as the atoms forming the basic skeleton of a
compound forming the adhesive layer of the optical device of the present
invention. For example, silicon atoms are used to provide an adhesive
layer having excellent heat resistance, weatherability, humidity
resistance and chemical resistance. A matrix is formed by using titanium,
zirconium, aluminum or germanium alone or mixing with other element such
as silicon to provide an adhesive layer having excellent heat resistance,
weatherability, humidity resistance and chemical resistance and a large
refractive index. At least one of the network forming atoms of the present
invention is bonded to other network forming atom(s) through a polyvalent
hydrocarbon group having at least two carbon atoms.
When the above network forming atom is a silicon atom and the polyvalent
hydrocarbon group is a divalent hydrocarbon group such as an ethylene
group (--CH.sub.2 CH.sub.2 --), at least part of silicon atoms is bonded
to other silicon atom through the ethylene group as shown in the following
formula (3).
##STR1##
When the network forming atom is a silicon atom and the polyvalent
hydrocarbon group is a tervalent hydrocarbon group such as a
1,2,3-propanetoluyl group, the silicon atom is bonded to other silicon
atoms through the 1,2,3-propanetoluyl group as shown in the following
formula (4).
##STR2##
Thus, the elasticity of the adhesive layer is increased and the fragility
of the adhesive layer is reduced by the above structure that the network
forming atom of the present invention is bonded to other network forming
atom(s) through a polyvalent hydrocarbon group compared with a
conventional structure that a network forming atom is bonded to other
network forming atom through an oxygen atom, whereby a cohesive failure
hardly occurs and adhesion strength increases.
In the adhesive layer of the present invention, at least part of the
network forming atoms is directly bonded to at least one monovalent
hydrocarbon group selected from the group consisting of an alkyl group,
phenyl group, monovalent fluorine-containing hydrocarbon group and
monovalent sulfur-containing hydrocarbon group. When the monovalent
hydrocarbon group is existent in the matrix comprising the network forming
atoms and oxygen atoms, it provides oxidation resistance, heat resistance
and solvent resistance to the matrix. Since the network forming atom in
the present invention has such a structure that it is bonded to other
network forming atom through the monovalent hydrocarbon group, an adhesive
material having excellent adhesion strength and environmental resistance
(heat resistance, weatherability, humidity resistance and chemical
resistance) can be provided.
When the amount of the polyvalent hydrocarbon group contained in the
adhesive layer is too large, the molecular weight of a sIloxane is reduced
relatively and the viscosity of a liquid composition lowers, thereby
deteriorating coating work efficiency and when the amount is too small,
the effect of increasing the adhesion strength of the adhesive layer is
reduced, the molecular weight of a siloxane increases relatively, and the
viscosity of a liquid composition becomes too high, thereby deteriorating
coating work efficiency. When the amount of the monovalent hydrocarbon
group contained in the adhesive layer is too large, adhesion to glass
lowers and when the amount is too small, the oxidation resistance of the
adhesive layer lowers. Therefore, the adhesive layer contains the
polyvalent hydrocarbon group and the monovalent hydrocarbon group in
amounts of preferably 0.01 to 30 wt % and 30 to 80 wt %, more preferably
0.02 to 20 wt % and 40 to 70 wt %, respectively.
In the present invention, the contents of each of the network forming
atoms, the polyvalent hydrocarbon group and the monovalent hydrocarbon
group are adjusted such that the refractive index value of the adhesive
layer should approximate to the refractive index values of the at least
two optically transparent optical parts. In concrete terms, when the
refractive indices of two adjacent optical parts are represented by
n.sub.1 and n.sub.2 (with the proviso that n.sub.1.gtoreq.n.sub.2), the
adhesive layer between the adjacent optical parts preferably has a
refractive index n.sub.3 represented by the following expression (1). The
adhesive layer more preferably has a refractive index n.sub.3 represented
by the following expression (2).
(n.sub.1.multidot.n.sub.2 +L )-(((n.sub.1.multidot.n.sub.2 +L
)-n.sub.2)/3)-0.05.ltoreq.n.sub.3.ltoreq.(n.sub.1.multidot.n.sub.2 +L
)+((n.sub.1 -(n.sub.1.multidot.n.sub.2 +L ))/3)+0.05 (1)
(n.sub.1.multidot.n.sub.2 +L )-(((n.sub.1.multidot.n.sub.2 +L
)-n.sub.2)/4)-0.03.ltoreq.n.sub.3.ltoreq.(n.sub.1.multidot.n.sub.2 +L
)+((n.sub.1 -(n.sub.1.multidot.n.sub.2 +L ))/4)+0.03 (2)
For example, when optical fibers are bonded to each other and have a
refractive index of 1.45, 1.40.ltoreq.n.sub.3.ltoreq.1.50 according to the
above expression (1) and 1.42.ltoreq.n.sub.3.ltoreq.1.48 according to the
above expression (2). An optical device having a small optical propagation
loss can be obtained by adjusting the refractive index of the adhesive
layer. As for optical parts other than optical fibers, such as lenses,
filters, optical waveguides, diffraction gratings and optically active
elements, an optical device having a small optical propagation loss can be
provided by adjusting the refractive index.
The method of forming the adhesive layer of the present invention will be
described hereinafter.
Methods of forming a bond between the polyvalent hydrocarbon group and two
or more network forming atoms include one in which a raw material compound
having a polyvalent hydrocarbon group bonded to two or more network
forming atoms is used, one in which a metal compound having a
polymerizable reactive group directly bonded to a metal compound is formed
by thermal and/or optical polymerization, and one in which the bond is
formed by a hydrosililation reaction between an alkenyl compound and a
hydrogenated silicon compound. The method in which a raw material compound
having a polyvalent hydrocarbon group bonded to two or more network
forming atoms is used is exemplified by one in which the raw material
compound is formed by hydrolysis and a dehydration condensation reaction
among bis(trialkoxysilyl)ethane, bis(trialkoxysilyl)propane and
bis(trialkoxysilyl)butane as raw materials. The method of forming the
metal compound by thermal and/or optical polymerization is exemplified by
one in which the metal compound is formed by mixing an optically radical
generating agent with vinyltrialkoxysilane or vinyl both-terminated
polydimethylsiloxane and polymerizing these through optical exposure. The
method of forming the bond by a hydrosililation reaction between an
alkenyl compound and a hydrogenated silicon compound is exemplified by one
in which the bond is formed by a hydrosililation reaction between vinyl
both-terminated dimethylsiloxane and hydrogenated dimethylsiloxane in the
presence of a platinum catalyst. Out of these forming methods, the method
of forming the bond through a hydrosililation reaction between an alkenyl
compound and a hydrogenated silicon compound is preferred because the heat
resistance of the formed adhesive layer is particularly excellent the
formation of bubbles caused by a reaction by-product can be prevented and
shrinkage in the curing step is small.
Preferably, the adhesive composition for bonding optical parts together
comprises the following components (A) to (C):
(A) organopolysiloxane having at least two alkenyl groups having 4 or less
carbon atoms bonded to silicon atoms in the molecule;
(B) organohydrogenpolysiloxane having at least two hydrogen atoms bonded to
silicon atoms in the molecule; and
(C) a platinum-based catalyst.
Examples of the organopolysiloxane compound having at least two alkenyl
groups having 4 or less carbon atoms bonded to silicon atoms in the
molecule (component (A)) include hydrogen terminated polydimethyluiloxane
compounds, methylhydrogensiloxane-dimethylsiloxane copolymer compounds,
polymethylhydrogensiloxane compounds, polyethylhydrogensiloxane compounds,
polyphenyl(dimethylhydrogensiloxy)siloxane hydrogen terminated compounds,
methylhydrogensiloxane-phenylmethylsiloxane copolymer compounds and
methylhydrogensiloxane-octylmethylsiloxane copolymer compounds having a
vinyl group, vinyloxy group (2 carbon atoms), allyl group, allyloxy group
(3 carbon atoms), acryl group, acryloxy group (2 carbon atoms), methacryl
group or methacryloxy group (3 carbon atoms). Out of these, both terminal
vinyl group dimethylsiloxane polymers represented by the following formula
(5), vinylmethylsiloxane-dimethylsiloxane copolymers represented by the
following formula (6), both terminal vinyl group
diphenylsiloxane-dimethylsiloxane copolymers represented by the following
formula (7) and both terminal vinyl group
methyltrimethylpropylsiloxanedimethylsiloxanes represented by the
following formula (8) are preferred. The component (A) preferably has a
viscosity of 100 to 250,000 cS at 25.degree. C. from the viewpoint of
coating work efficiency.
##STR3##
Examples of the organohydrogenpolysiloxane compound having at least two
hydrogen atoms bonded to silicon atoms in the molecule (component (B))
include hydrogen terminated polydimethylsiloxane compounds represented by
the following formula (9), methylhydrogensiloxane-dimethylsiloxane
copolymer compounds represented by the following formula (10),
polyphenyl(dimethylhydrogensiloxane)siloxane hydrogen terminated compounds
represented by the following formula (11),
methyltrifluoropropylsiloxane(dimethylsiloxane)copolymer represented by
the following formula (12), polymethylhydrogensiloxane compounds,
polyethylhydrogensiloxane compounds and
methylhydrogensiloxane-phenylmethylsiloxane copolymer compounds.
##STR4##
Examples of the platinum-based catalyst (component (C)) used in the
adhesive composition of the present invention include a platinum-slloxane
complex, platinum-olefin complex, platinum-(.beta.-diketone)complex,
platinum-azo complex or the like. Preferred examples of the catalyst
include platinum-carbonylvinylmethyl complex,
platinum-divinyltetramethyldisiloxane complex,
platinum-cyclovinylmethylsiloxane complex, platinum-octylaldehyde/octanol
complex and the like.
The contents of the component (A) and the component (B) in the adhesive
composition are desirably such that the number of the hydrogen atoms
contained in the component (B) is 0.4 to 6.0 times, more preferably 0.6 to
4.0 times the total number of alkenyl groups contained in the component
(A). The above platinum-based catalyst (component (C)) is preferably
contained in an amount of 10 to 1,000 ppm based on the total weight of the
component (A) and the component (B) because appropriate curing speed is
maintained and appropriate pot life is achieved.
The adhesive composition of the present invention may contain a
tetraalkoxide (trialkoxide in the case of aluminum) of at least one type
of network forming atoms selected from the group consisting of silicon,
titanium, zirconium, aluminum and germanium and a condensate of one or
more of these metal alkoxides in small quantities in addition to the above
components (A) to (C). These components cause the formation of bubbles and
volume shrinkage through dehydration or dealcoholation during the curing
reaction of the adhesive layer. The total content of these components may
be 20 wt % or less based on the total weight of the adhesive composition.
A description is subsequently given of the optical parts of the present
invention. Examples of the optical parts of the present invention include
optical fibers, lenses, filters, optical waveguides, diffraction gratings
and optical active elements. The optical fibers include single-mode
optical fibers and multi-mode optical fibers. The lenses include
refractive index distribution lenses, spherical lenses, aspherical lenses
and plano-convex lenses. The optical filters include narrow-band filters
composed of a dielectric multi-layer film, band-pass filters and
polarization filters. The optical waveguides include single-mode optical
waveguides and multi-mode optical waveguides. These optical waveguides may
have a Bragg diffraction grating whose refractive index is modulated
periodically. The materials forming these optical parts include glass
materials, plastic materials and organic-inorganic composite materials.
The materials forming the above optical parts preferably have a linear
expansion coefficient of 1.5.times.10.sup.-5 /.degree. C. or less. When
the linear expansion coefficient of the base material is higher than
1.5.times.10.sup.-5 /.degree. C. like a plastic optical part made from
polypropylene having a high thermal expansion coefficient (9 to
15.times.10.sup.-5 /.degree. C.), an optical part and an adhesive layer
peel off at the interface or the adhesive layer cracks in the heating step
after the application of the adhesive. General inorganic glass has a
linear expansion coefficient of 1.5.times.10.sup.-5 /.degree. C. or less.
At least the bonded surface of an optical part is preferably made from an
oxide. When the bonded surface of an optical part is not made from an
oxide, adhesion strength lowers in the step of forming the adhesive layer
or the bonded surface and the adhesive layer peel off at the interface as
the case may be. Preferred examples of the base material include oxide
glasses such as silicate-based glass, boric acid-based glass and
phosphoric acid-based glass, quartz, ceramics, epoxy resins, glass fiber
reinforced polystyrene and the like. The adhesive layer of the present
invention is hardly bonded to a metal as it is but when the surface of the
metal is treated with an oxidizing agent, the metal can be used as a part
to be bonded.
To assemble these optical parts, the optically transparent adhesive
composition of the present invention is placed, filled or spread out
between a first optical part and a second optical part and cured to form a
bonded portion having predetermined strength. As for the curing of the
adhesive, an adhesive composition which is cured in a few minutes can be
obtained by increasing the amount of a curing catalyst and an adhesive
composition having a pot life of a few hours can be obtained by reducing
the amount of a curing catalyst. The curing time can be shortened by
carrying out a heat treatment as required. A reaction retardant or curing
accelerator may be added in an amount of 40 wt % or less, preferably 30 wt
% or less as required. The curing time can be freely controlled by adding
a reaction retardant and curing accelerator.
Examples are given below to further illustrate the present invention.
EXAMPLES
Preparation of First Raw Materials (Raw Materials A to I)
(Raw Material A)
0.039 mol (5 g) of dimethyldichlorosilane, 4 mols (72 g) of water and 1 mol
(120.6 g) of dimethylvinylchlorosilane were mixed together and reacted
with one another at 60.degree. C. for 2 hours. Water and unreacted
dimethylvinylchlorosilane were removed from the reaction mixture under
reduced pressure and the reaction mixture was dehydrated to obtain
terminal vinyl polydimethylsiloxane (viscosity: 1.000 cS, molecular
weight: 28.000, content of vinyl group: 0.18 to 0.26 wt %) (raw material
A).
(Raw Material B)
1 mol (253.13 g) of diphenyldichlorosilane, 1 mol (129.3 g) of
dimethyldichlorosilane, 4 mols (72 g) of water and 1 mol (120.6 g) of
dimethylvinylchlorosilane were mixed together and reacted with one another
at 60.degree. C. for 2 hours. Water and unreacted
dimethylvinylchlorosilane were removed from the reaction mixture under
reduced pressure and the reaction mixture was dehydrated to obtain a vinyl
terminated diphenylsiloxane-dimethylsiloxane copolymer (viscosity: 500 cS,
molecular weight: 9,500, content of phenyl group: 18 to 22 wt %, content
of vinyl group: 0.37 to 0.42 wt %) (raw material B).
(Raw Material C)
1 mol of methyltrifluoropropyldichlorosilane, 1 mol of
dimethyldichlorosilane, 4 mols of water and 1 mol of
dimethylvinylchlorosilane were mixed together and reacted with one another
at 60.degree. C. for 2 hours. Water and unreacted
dimethylvinylchlorosilane were removed from the reaction mixture under
reduced pressure and the reaction mixture was dehydrated to obtain a vinyl
terminated methyltrifluoropropylsiloxane-dimethylsiloxane copolymer
(viscosity: 500 cS, molecular weight: 9,500) (raw material C).
(Raw Material D)
5 g (0.0676 mol) of ethanol and 0.01 mol of an aqueous solution of
hydrochloric acid containing 10 mols of water were added to 5 g (0.0240
mol) of tetraethoxysilane and stirred at room temperature for 2 hours.
11.58 g (0.096 mol) of dimethylvinylchlorosilane which was 4 molar
equivalents of tetraethoxysilane was added to the resulting solution to
carry out a reaction at 60.degree. C. for 2 hours. Ethanol, water and
unreacted dimethylvinylchlorosilane were removed from the reaction mixture
under reduced pressure and the reaction mixture was dehydrated to obtain
an equivalent to the Vinyl Q Resin (of Guerest Co., Ltd., viscosity of
5,000 cS) (raw material D).
(Raw Material E)
1.89 g (0.0189 mol) of acetylacetone, 5 g of isopropanol and 0.01 mol of an
aqueous solution of hydrochloric acid containing 4 mols of water were
added to 5 g (0.0189 mol) of tetraisopropoxytitanium and stirred at room
temperature for 2 hours. 9.12 g (0.0756 mol) of dimethylvinylchlorosilane
which was 4 molar equivalents of tetraisopropoxytitanium was added to the
resulting solution to carry out a reaction at 60.degree. C. for 2 hours.
Isopropanol, acetylacetone, water and unreacted dimethylvinylchlorosilane
were removed from the reaction mixture under reduced pressure to obtain a
vinyl terminated titanium oxide condensate (raw material E).
(Raw Material F)
2 molar equivalents of acetylacetone, 5 g of butanol and 0.01 mol of an
aqueous solution of hydrochloric acid containing 4 molar equivalents of
water were added to 5 g (0.0130 mol) of tetrabutoxyzirconium and stirred
at room temperature for 2 hours. 6.27 g (0.052 mol) of
dimethylvinylchlorosilane which was 4 molar equivalents of
tetrabutoxyzirconium was added to the resulting solution to carry out a
reaction at 60.degree. C. for 2 hours. Isopropanol, acetylacetone, water
and unreacted dimethylvinylchlorosilane were removed from the reaction
mixture under reduced pressure to obtain a vinyl terminated zirconium
oxide condensate (raw material F).
(Raw Material G)
1 molar equivalent of acetylacetone, 5 g of butanol and 0.01 mol of an
aqueous solution of hydrochloric acid containing 4 molar equivalents of
water were added to 5 g (0.0183 mol) of tri-sec-butoxyaluminum and stirred
at room temperature for 2 hours. 8.83 g (0.0732 mol) of
dimethylvinylchlorosilane which was 4 molar equivalents of
tri-sec-butoxyaluminum was added to the resulting solution to carry out a
reaction at 60.degree. C. for 2 hours. Isopropanol, acetylacetone, water
and unreacted dimethylvinylchlorosilane were removed from the reaction
mixture under reduced pressure to obtain a vinyl terminated aluminum oxide
condensate (raw material G).
(Raw Material H)
2 molar equivalents of water and 8.10 g (0.0672 mol) of
dimethylvinylchlorosilane were added to 5 g (0.0168 mol) of
diphenyldichlorogermanium to carry out a reaction at 60.degree. C. for 2
hours. Water and unreacted dimethylvinylchlorosilane were removed from the
reaction mixture under reduced pressure to obtain a vinyl terminated
germanium oxide condensate (raw material H).
(Raw Material I)
Raw material I was prepared in the same manner as in the preparation of raw
material A except that 1 mol of allyldimethylchlorosilane was used in
place of 1 mol of dimethylvinylchlorosilane used for the preparation of
raw material A.
Optical Part
(Optical Fiber)
A glass single-mode optical fiber (clad diameter: 120 .mu.m, core diameter:
10 .mu.m, refractive index of core: 1.46, refractive index of clad: 1.44)
was prepared.
(Lens)
A glass microlens (Selfoc Microlens SMC18, diameter: 1.8 mm, length: 4.43
mm (0.23 pitch, refractive index of center portion: 1.590, distribution
coefficient g=0.326, 1 pitch (=2 .pi./g)=19.27 mm) was prepared.
(Filter)
A bandpass filter was prepared by laminating a silicon oxide layer
(refractive index: 1.46) and a titanium oxide layer (refractive index:
2.1) on one side of a glass substrate (refractive index: 1.46)
alternately.
(Optical Waveguide)
An optically radical forming agent was added in an amount of 3 wt % based
on the total weight to a liquid composition obtained by mixing together a
silica raw material solution obtained by hydrolyzing
acryloxypropyltrimethoxysilane with 0.1N hydrochloric acid and a zirconia
raw material obtained by treating zirconium tetrabutoxide with an
equimolar amount of acrylic acid in a Si/Zr ratio of 1:1 to obtain a
solution for forming an optical waveguide. This solution was applied to a
silicon substrate having a 8 .mu.m-thick silica film (V-shaped groove for
fixing an optical fiber was formed in an end portion thereof) by spin
coating and heated at 80.degree. C. for 10 minutes and a waveguide portion
was exposed to light by a high-pressure mercury lamp (at 10 mW for 15
seconds) through a photomask. Unexposed portions were dissolved in
isopropanol and removed. A liquid composition whose Si/Zr ratio was
adjusted to 1.2:1 was coated on the substrate and dried to obtain an
embedded waveguide.
(Waveguide Type Diffraction Grating)
A Bragg grating was formed on the above optical waveguide by a double-beam
interference exposure method to obtain a waveguide type diffraction
grating.
The refractive index values at related sites of the above optical parts are
shown in Table 1.
Table 1
optical part refractive index
optical fiber (core) 1.45
lens (center portion) 1.590
optical waveguide (core) 1.52
optical filter 1.46
Preparation of Adhesive Compositions
As shown in Table 2, methylhydrogensiloxane-dimethylsiloxane copolymer J
(viscosity: 25 to 35 cS, molecular weight: 2,000) or
methylhydrogensiloxane-phenylmethylsiloxane copolymer K (viscosity: 100
cS) (copolymer J or K will be referred to as "second raw materials"
hereinafter) was added to the first raw material to ensure that the number
of hydrogen atoms contained in the second raw material should be 0.4 to
6.0 times the total number of alkenyl groups contained in the above first
raw material and a platinum catalyst
(platinum-divinyltetramethyldisiloxane complex) was mixed in an amount of
100 ppm based on the total to obtain adhesive compositions (1) to (17).
TABLE 2
adhesive
second raw
adhesive first raw material material ratio of number of
composition quantity quantity quantity hydrogen atoms to
total
No. type (g) type (g) type (g) number of alkenyl
groups
1 A 0.5 -- -- J 0.01 1.5
2 B 0.6 -- -- J 0.01 1.5
3 C 0.5 -- -- J 0.01 1.5
4 D 0.4 -- -- J 0.01 1.5
5 E 0.4 -- -- J 0.01 1.5
6 F 0.4 -- -- J 0.01 1.5
7 G 0.5 -- -- J 0.01 1.5
8 H 0.4 -- -- J 0.01 1.5
9 A 0.26 B 0.14 J 0.01 1.5
10 A 0.08 B 0.32 K 0.01 2.0
11 B 0.16 C 0.24 J 0.01 1.5
12 B 0.28 D 0.12 J 0.01 1.5
13 A 0.16 E 0.24 J 0.01 1.5
14 A 0.16 F 0.24 J 0.01 1.5
15 A 0.2 G 0.20 J 0.01 1.5
16 A 0.32 H 0.08 J 0.01 1.5
17 I 0.40 -- -- J 0.01 1.5
10 mg of each of the above adhesive compositions (1) to (17) was dropped
onto a first slide glass (25 mm.times.50 mm.times.1.2 mm), a second slide
glass was placed upon the first slide glass to spread the adhesive
composition to a size of 25 mm.times.25 mm, and the adhesive composition
was then heated on a hot plate at 200.degree. C. for 15 minutes. The
appearance of the adhesive layer between the first and second glasses was
observed to check the formation of air bubbles and the cloudiness of the
layer. 1 g of the adhesive composition was placed in a 3 ml glass sample
bottle and heated at 200.degree. C. for 30 minutes to measure the volume
of the adhesive composition before and after the heat treatment to
evaluate a volume shrinkage factor (%) represented by 100.times.(volume
before heating-volume after heating)/(volume before heating). To evaluate
the adhesion strength (cohesive failure rate) of the adhesive layer, the
glass plates on both sides of the adhesive layer were pulled in opposite
directions at a rate of 50 cm/min to measure adhesion (shear) strength
(N/mm.sup.2). The results are shown in Table 3. In Examples (adhesive
compositions (1) to (17)), the formation of bubbles was not observed
during the heat treatment, volume shrinkage was very small, and adhesion
strength was sufficient. Rupture did not occur at the interface between
the adhesive layer after an adhesion strength test and glass but was seen
in the interior of the adhesive layer.
Comparative Example 1
1.33 ml of polydimethylsiloxane (PDMS), 35.6 ml of methyltriethoxysilane
(MTES) and 2.67 ml of phenyltrifluorosilane (PTFS) were injected into a
100 ml sample tube (molar ratio of 8:83:9) and stirred at room temperature
for 5 minutes by covering the tube. The mixture was heated at 70.degree.
C., and 5.4 g of water was added and strongly stirred for 30 minutes. The
reaction mixture was separated into two layers at first but became uniform
after that. By removing the cover, the reaction mixture was left in the
atmosphere for 1 day and the solvent was naturally dried to obtain an
adhesive composition (18). The formation of bubbles during the heat
treatment, volume shrinkage and adhesion strength of this adhesive
composition were measured in the same manner as the above adhesive
compositions (1 to 17). The results are shown in Table 3. Bubbles were
formed during the heat treatment and air bubbles continuous from the
center to the end portions of glass were formed in the adhesive
composition (18) shown as Comparative Example. Along with the generation
of gas, volume shrinkage was observed and adhesion strength was not
sufficient. Rupture did not occur at the interface | | |
