U.S. patent application number 14/561356 was filed with the patent office on 2015-03-26 for encapsulating sheet, light emitting diode device, and producing method thereof.
This patent application is currently assigned to NITTO DENKO CORPORATION. The applicant listed for this patent is NITTO DENKO CORPORATION. Invention is credited to Hiroyuki KATAYAMA.
Application Number | 20150087095 14/561356 |
Document ID | / |
Family ID | 47827003 |
Filed Date | 2015-03-26 |
United States Patent
Application |
20150087095 |
Kind Code |
A1 |
KATAYAMA; Hiroyuki |
March 26, 2015 |
ENCAPSULATING SHEET, LIGHT EMITTING DIODE DEVICE, AND PRODUCING
METHOD THEREOF
Abstract
An encapsulating sheet includes a transparent layer in which a
concave portion that is dented from the surface inwardly is formed
and a phosphor encapsulating layer which fills the concave portion.
The transparent layer is formed from a transparent composition
containing a first silicone resin composition and the phosphor
encapsulating layer is formed from a phosphor encapsulating
composition containing a phosphor and a second silicone resin
composition.
Inventors: |
KATAYAMA; Hiroyuki; (Osaka,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NITTO DENKO CORPORATION |
Osaka |
|
JP |
|
|
Assignee: |
NITTO DENKO CORPORATION
Osaka
JP
|
Family ID: |
47827003 |
Appl. No.: |
14/561356 |
Filed: |
December 5, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13784013 |
Mar 4, 2013 |
8937329 |
|
|
14561356 |
|
|
|
|
Current U.S.
Class: |
438/27 |
Current CPC
Class: |
H01L 33/005 20130101;
H01L 33/56 20130101; H01L 33/52 20130101; H01L 33/54 20130101; H01L
33/50 20130101; H01L 2924/0002 20130101; H01L 2924/0002 20130101;
Y10T 428/24521 20150115; H01L 2933/005 20130101; H01L 2933/0041
20130101; H01L 33/501 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
438/27 |
International
Class: |
H01L 33/52 20060101
H01L033/52; H01L 33/00 20060101 H01L033/00; H01L 33/50 20060101
H01L033/50 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 6, 2012 |
JP |
2012-049032 |
Claims
1. A method for producing a light emitting diode device, allowing
encapsulation of a light emitting diode element by an encapsulating
sheet, comprising the steps of: preparing an encapsulating sheet,
wherein the encapsulating sheet comprises a transparent layer in
which a concave portion that is dented from the surface inwardly is
formed and a phosphor encapsulating layer which fills the concave
portion, and the transparent layer is formed from a transparent
composition containing a first silicone resin composition and the
phosphor encapsulating layer is formed from a phosphor
encapsulating composition containing a phosphor and a second
silicone resin composition; and embedding the light emitting diode
element in the phosphor encapsulating layer in the encapsulating
sheet.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. application Ser.
No. 13/784,013 filed Mar. 4, 2013, which claims priority from
Japanese Patent Application No. 2012-049032 filed on Mar. 6, 2012,
the contents of which are hereby incorporated by reference into
this application.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an encapsulating sheet, a
light emitting diode device, and a producing method thereof, to be
specific, to an encapsulating sheet, a method for producing a light
emitting diode device using the encapsulating sheet, and a light
emitting diode device produced by the method.
[0004] 2. Description of Related Art
[0005] A light emitting diode device is, for example, provided with
an LED (a light emitting diode element) which is mounted on the
upper surface of a board and emits blue light, a phosphor layer
which is capable of converting the blue light into yellow light and
is provided on the LED, and an encapsulating layer which
encapsulates the LED. The light emitting diode device emits
high-energy white light by color mixing of the blue light, which is
emitted from the LED that is encapsulated by the encapsulating
layer and transmits through the phosphor layer, and the yellow
light, which is converted in wavelength from a part of the blue
light in the phosphor layer.
[0006] As a method for producing the light emitting diode device,
the following method has been proposed (ref: for example, Japanese
Unexamined Patent Publications No. 2009-60031 and No.
2010-123802).
[0007] That is, in Japanese Unexamined Patent Publication No.
2009-60031, first, an integrated-type encapsulating sheet is
prepared. The integrated-type encapsulating sheet includes a resin
sheet A (a first layer) that is prepared from an epoxy resin and is
formed with a hole and a resin layer B (a second layer) that is
formed by pouring a silicone varnish containing a phosphor and a
silicone gel into the hole in the resin sheet A. Next, the
integrated-type encapsulating sheet is laminated on a board on
which an LED element is mounted so that the second layer is brought
into contact with the LED element to be subsequently subjected to a
thermal compression bonding and then, a post curing. In this
manner, an optical semiconductor device is obtained.
[0008] Also, in Japanese Unexamined Patent Publication No.
2010-123802, first, a first resin layer which is prepared and
formed from a solution containing a phosphor and a silicone
elastomer is laminated on the entire surface of a second resin
layer which is prepared and formed from a silicone resin solution,
so that a semiconductor encapsulating sheet is prepared. Next, the
semiconductor encapsulating sheet is put on a board on which an LED
chip is mounted so that the second resin layer in the semiconductor
encapsulating sheet is brought into contact with the LED chip to be
subsequently subjected to a thermal compression bonding and then, a
post curing. In this manner, an optical semiconductor device is
obtained.
SUMMARY OF THE INVENTION
[0009] However, in the optical semiconductor device in Japanese
Unexamined Patent Publication No. 2009-60031, when the LED element
is allowed to light up for a long time, there may be a case where a
crack or coloring (to be specific, yellowing) occurs in the resin
sheet A in the integrated-type encapsulating sheet or furthermore,
a peeling occurs between the resin sheet A and the resin layer
B.
[0010] In Japanese Unexamined Patent Publication No. 2010-123802,
the first resin layer containing the phosphor is laminated on the
entire surface of the second resin layer to prepare the
semiconductor encapsulating sheet. Therefore, the mixing amount of
the phosphor in one piece of the semiconductor encapsulating sheet
is increased and thus, the production cost of the semiconductor
encapsulating sheet is increased, leading to an increase in the
production cost of the optical semiconductor device.
[0011] On the other hand, there is a disadvantage that when the
mixing amount of the phosphor in one piece of the semiconductor
encapsulating sheet is reduced, the concentration of the phosphor
around the LED chip is reduced, so that unevenness in chromaticity
of the light emitted from the LED chip is increased.
[0012] It is an object of the present invention to provide an
encapsulating sheet which is capable of suppressing a crack and
coloring in a transparent layer and suppressing a peeling between
the transparent layer and a phosphor encapsulating layer and in
which the production cost is reduced, a method for producing a
light emitting diode device which uses the encapsulating sheet, and
a light emitting diode device which is produced by the method and
in which the unevenness in chromaticity is reduced.
[0013] An encapsulating sheet of the present invention includes a
transparent layer in which a concave portion that is dented from
the surface inwardly is formed and a phosphor encapsulating layer
which fills the concave portion, wherein the transparent layer is
formed from a transparent composition containing a first silicone
resin composition and the phosphor encapsulating layer is formed
from a phosphor encapsulating composition containing a phosphor and
a second silicone resin composition.
[0014] In the encapsulating sheet of the present invention, it is
preferable that the first silicone resin composition and/or the
second silicone resin composition are/is a thermosetting silicone
resin composition.
[0015] In the encapsulating sheet of the present invention, it is
preferable that the thermosetting silicone resin composition is a
thermosetting silicone resin composition before final curing.
[0016] In the encapsulating sheet of the present invention, it is
preferable that the thermosetting silicone resin composition before
final curing in the transparent layer is a first-step cured
material of a two-step curable type silicone resin composition.
[0017] In the encapsulating sheet of the present invention, it is
preferable that the thermosetting silicone resin composition before
final curing in the phosphor encapsulating layer is a first-step
cured material of a two-step curable type silicone resin
composition and/or a thermoplastic material of a silicone resin
composition having both thermoplastic properties and thermosetting
properties.
[0018] A method for producing a light emitting diode device of the
present invention, allowing encapsulation of a light emitting diode
element by an encapsulating sheet, includes the steps of preparing
the above-described encapsulating sheet and embedding the light
emitting diode element in the phosphor encapsulating layer in the
encapsulating sheet.
[0019] A light emitting diode device of the present invention is
produced by the above-described method for producing a light
emitting diode device.
[0020] In the encapsulating sheet of the present invention, the
method for producing a light emitting diode device of the present
invention using the encapsulating sheet, and the light emitting
diode device of the present invention produced by the method, the
transparent layer is formed from the transparent composition
containing the first silicone resin composition, so that a crack
and coloring in the transparent layer can be suppressed.
[0021] The transparent layer is formed from the transparent
composition containing the first silicone resin composition and the
phosphor encapsulating layer is formed from the phosphor
encapsulating composition containing the second silicone resin
composition, so that the affinity between the transparent layer and
the phosphor encapsulating layer is high and therefore, a peeling
therebetween can be suppressed.
[0022] The phosphor encapsulating layer is, in the concave portion
formed in the transparent layer, formed from the phosphor
encapsulating composition containing the phosphor. The light
emitting diode element is embedded by the phosphor encapsulating
layer, so that the mixing amount of the phosphor in the phosphor
encapsulating layer in which the light emitting diode element is
embedded is sufficiently ensured and light emitted from the light
emitting diode element can be surely converted, while the mixing
amount of the phosphor in the encapsulating sheet can be reduced,
compared with that in a case where the phosphor encapsulating layer
is formed on the entire surface of the transparent layer.
[0023] Therefore, the production cost of the encapsulating sheet
can be reduced.
[0024] As a result, in the method for producing a light emitting
diode device using the encapsulating sheet, the production cost of
the light emitting diode device can be reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 shows a sectional view of one embodiment of an
encapsulating sheet of the present invention.
[0026] FIG. 2 shows a transparent layer in the encapsulating sheet
shown in FIG. 1:
[0027] (a) illustrating a plan view and
[0028] (b) illustrating a sectional view along the A-A line.
[0029] FIG. 3 shows views for illustrating a method (a compression
molding method) for fabricating the transparent layer shown in FIG.
2:
[0030] (a) illustrating a step of charging a transparent
composition into a compression molding machine and
[0031] (b) illustrating a step of closing a mold die.
[0032] FIG. 4 shows views for illustrating a method (a thermal
pressing method) for fabricating the transparent layer shown in
FIG. 2:
[0033] (a) illustrating a step of setting a transparent sheet into
a thermal pressing machine and
[0034] (b) illustrating a step of conducting thermal pressing.
[0035] FIG. 5 shows views for illustrating a method (a laminating
method) for fabricating the transparent layer shown in FIG. 2:
[0036] (a) illustrating a step of preparing two pieces of the
transparent sheets,
[0037] (b) illustrating a step of forming through holes in one
piece of the transparent sheet, and
[0038] (c) illustrating a step of attaching the two pieces of the
transparent sheets.
[0039] FIG. 6 shows views for illustrating a method for producing
one embodiment of the encapsulating sheet of the present
invention:
[0040] (a) illustrating a step of disposing the encapsulating sheet
on a board and
[0041] (b) illustrating a step of compressively bonding the
encapsulating sheet with respect to the board.
[0042] FIG. 7 shows a plan view of the board shown in FIG. 6
(a).
DETAILED DESCRIPTION OF THE INVENTION
[0043] FIG. 1 shows a sectional view of one embodiment of an
encapsulating sheet of the present invention. FIG. 2 shows a
transparent layer in the encapsulating sheet shown in FIG. 1: (a)
illustrating a plan view and (b) illustrating a sectional view
along the A-A line. FIG. 3 shows views for illustrating a method (a
compression molding method) for fabricating the transparent layer
shown in FIG. 2: (a) illustrating a step of charging a transparent
composition into a compression molding machine and (b) illustrating
a step of closing a mold die. FIG. 4 shows views for illustrating a
method (a thermal pressing method) for fabricating the transparent
layer shown in FIG. 2: (a) illustrating a step of setting a
transparent sheet into a thermal pressing machine and (b)
illustrating a step of conducting thermal pressing. FIG. 5 shows
views for illustrating a method (a laminating method) for
fabricating the transparent layer shown in FIG. 2: (a) illustrating
a step of preparing two pieces of the transparent sheets, (b)
illustrating a step of forming through holes in one piece of the
transparent sheet, and (c) illustrating a step of attaching the two
pieces of the transparent sheets.
[0044] In FIG. 1, an encapsulating sheet 1 includes a transparent
layer 2 and phosphor encapsulating layers 3.
[0045] As shown in FIGS. 2 (a) and 2 (b), the transparent layer 2
is formed into a sheet shape and on the top side of the transparent
layer 2, concave portions 4 which are dented from the surface
inwardly in the thickness direction are formed.
[0046] The concave portions 4 are disposed in alignment at spaced
intervals to each other in the plane direction (a direction
perpendicular to the thickness direction) of the transparent layer
2. Each of the concave portions 4 is open upwardly, and is formed
into a generally circular shape in plane view and into a generally
rectangular shape in sectional view.
[0047] The size of each of the concave portions 4 is appropriately
set in accordance with the arrangement and the size of light
emitting diode elements 11 (described later, ref: FIGS. 6 (b) and
7). To be specific, the size of each of the concave portions 4 is
as follows: an inner diameter (the maximum length in the plane
direction) of, for example, 0.5 to 10 mm, or preferably 1 to 5 mm
and a depth (a length in the thickness direction) of, in view of
protecting the light emitting diode elements 11 (and wires in a
case where the light emitting diode elements 11 are wire-bonding
connected to a board 12 (described later)), for example, 0.02 to
1.0 mm, or preferably 0.05 to 0.5 mm. The gap (the closest gap)
between the concave portions 4 is, for example, 0.5 to 10 mm, or
preferably 1 to 5 mm.
[0048] The thickness of the transparent layer 2, that is, the
thickness of the transparent layer 2 around the concave portions 4
is, in view of handling ability, for example, 0.05 to 5.0 mm, or
preferably 0.1 to 2.0 mm.
[0049] The transparent layer 2 is formed from a transparent
composition containing a first silicone resin composition.
[0050] An example of the first silicone resin composition includes
a thermosetting silicone resin composition such as a two-step
curable type silicone resin composition and a one-step curable type
silicone resin composition.
[0051] The two-step curable type silicone resin composition is
defined as a thermosetting silicone resin composition which has a
two-step reaction mechanism and in which a silicone resin
composition is brought into a B-stage state (a semi-cured state) in
the first-step reaction and is brought into a C-stage state (a
final curing state) in the second-step reaction.
[0052] The B-stage state is a state between an A-stage state in
which a silicone resin composition is soluble in a solvent and a
C-stage state in which a silicone resin composition is subjected to
a final curing. Also, the B-stage state is a state in which the
curing and the gelation of the silicone resin composition are
slightly progressed to be swollen but not to be completely
dissolved in a solvent and also to be softened but not to be melted
by heating.
[0053] On the other hand, the one-step curable type silicone resin
composition is defined as a thermosetting silicone resin
composition which has a one-step reaction mechanism and in which a
silicone resin composition is subjected to a final curing in the
first-step reaction.
[0054] An example of an uncured material (before cuing in the first
step) of the two-step curable type silicone resin composition
includes a condensation reaction and addition reaction curable type
silicone resin composition.
[0055] The condensation reaction and addition reaction curable type
silicone resin composition is a thermosetting silicone resin
composition which can be subjected to a condensation reaction and
an addition reaction by heating. To be specific, the condensation
reaction and addition reaction curable type silicone resin
composition is a thermosetting silicone resin composition which can
be subjected to a condensation reaction to be brought into a
B-stage state (a semi-cured state) by heating and then, be
subjected to an addition reaction (to be specific, for example, a
hydrosilylation reaction) to be brought into a C-stage state (a
final curing state) by further heating.
[0056] Examples of the condensation reaction and addition reaction
curable type silicone resin composition include a first
condensation reaction and addition reaction curable type silicone
resin composition which contains a polysiloxane containing silanol
groups at both ends, an alkenyl group-containing trialkoxysilane,
an organohydrogensiloxane, a condensation catalyst, and a
hydrosilylation catalyst; a second condensation reaction and
addition reaction curable type silicone resin composition which
contains a polysiloxane containing silanol groups at both ends, a
silicon compound containing an ethylenically unsaturated
hydrocarbon group (hereinafter, defined as an ethylenic silicon
compound), an epoxy group-containing silicon compound, an
organohydrogensiloxane, a condensation catalyst, and an addition
catalyst (a hydrosilylation catalyst); a third condensation
reaction and addition reaction curable type silicone resin
composition which contains a silicone oil containing silanol groups
at both ends, an alkenyl group-containing dialkoxyalkylsilane, an
organohydrogensiloxane, a condensation catalyst, and a
hydrosilylation catalyst; a fourth condensation reaction and
addition reaction curable type silicone resin composition which
contains an organopolysiloxane having, in one molecule, at least
two alkenylsilyl groups, an organopolysiloxane having, in one
molecule, at least two hydrosilyl groups, a hydrosilylation
catalyst, and a curing retarder; a fifth condensation reaction and
addition reaction curable type silicone resin composition which
contains a first organopolysiloxane having, in one molecule, both
at least two ethylenically unsaturated hydrocarbon groups and at
least two hydrosilyl groups, a second organopolysiloxane having, in
one molecule, at least two hydrosilyl groups without containing an
ethylenically unsaturated hydrocarbon group, a hydrosilylation
catalyst, and a hydrosilylation retarder; a sixth condensation
reaction and addition reaction curable type silicone resin
composition which contains a first organopolysiloxane having, in
one molecule, both at least two ethylenically unsaturated
hydrocarbon groups and at least two silanol groups, a second
organopolysiloxane having, in one molecule, at least two hydrosilyl
groups without containing an ethylenically unsaturated hydrocarbon
group, a hydrosilylation retarder, and a hydrosilylation catalyst;
a seventh condensation reaction and addition reaction curable type
silicone resin composition which contains a silicon compound, and a
boron compound or an aluminum compound; and an eighth condensation
reaction and addition reaction curable type silicone resin
composition which contains a polyaluminosiloxane and a silane
coupling agent.
[0057] These condensation reaction and addition reaction curable
type silicone resin compositions can be used alone or in
combination of two or more.
[0058] As the condensation reaction and addition reaction curable
type silicone resin composition, preferably, a second condensation
reaction and addition reaction curable type silicone resin
composition is used.
[0059] In the second condensation reaction and addition reaction
curable type silicone resin composition, the polysiloxane
containing silanol groups at both ends, the ethylenic silicon
compound, and the epoxy group-containing silicon compound are
condensation materials (materials subjected to a condensation
reaction) and the ethylenic silicon compound and the
organohydrogensiloxane are addition materials (materials subjected
to an addition reaction).
[0060] The polysiloxane containing silanol groups at both ends is
an organosiloxane which contains silanol groups (SiOH groups) at
both ends of a molecule and to be specific, is represented by the
following general formula (1).
##STR00001##
[0061] (where, in general formula (1), R.sup.1 represents a
monovalent hydrocarbon group selected from a saturated hydrocarbon
group and an aromatic hydrocarbon group. "n" represents an integer
of 1 or more.)
[0062] In the above-described general formula (1), in the
monovalent hydrocarbon group represented by R.sup.1, examples of
the saturated hydrocarbon group include a straight chain or
branched chain alkyl group having 1 to 6 carbon atoms (such as a
methyl group, an ethyl group, a propyl group, an isopropyl group, a
butyl group, an isobutyl group, a pentyl group, and a hexyl group)
and a cycloalkyl group having 3 to 6 carbon atoms (such as a
cyclopentyl group and a cyclohexyl group).
[0063] In the above-described general formula (1), in the
monovalent hydrocarbon group represented by R.sup.1, an example of
the aromatic hydrocarbon group includes an aryl group having 6 to
10 carbon atoms (such as a phenyl group and a naphthyl group).
[0064] In the above-described general formula (1), R.sup.1s may be
the same or different from each other. Preferably, R.sup.1s are the
same.
[0065] As the monovalent hydrocarbon group, preferably, an alkyl
group having 1 to 6 carbon atoms and an aryl group having 6 to 10
carbon atoms are used, or more preferably, in view of transparency,
thermal stability, and light resistance, a methyl group is
used.
[0066] In the above-described general formula (1), "n" is
preferably, in view of stability and/or handling ability, an
integer of 1 to 10000, or more preferably an integer of 1 to
1000.
[0067] "n" in the above-described general formula (1) is calculated
as an average value.
[0068] To be specific, examples of the polysiloxane containing
silanol groups at both ends include a polydimethylsiloxane
containing silanol groups at both ends, a polymethylphenylsiloxane
containing silanol groups at both ends, and a polydiphenylsiloxane
containing silanol groups at both ends.
[0069] These polysiloxanes containing silanol groups at both ends
can be used alone or in combination.
[0070] Of the polysiloxanes containing silanol groups at both ends,
preferably, a polydimethylsiloxane containing silanol groups at
both ends is used.
[0071] A commercially available product can be used as the
polysiloxane containing silanol groups at both ends. A polysiloxane
containing silanol groups at both ends synthesized in accordance
with a known method can be also used.
[0072] The number average molecular weight of the polysiloxane
containing silanol groups at both ends is, for example, in view of
stability and/or handling ability, 100 to 1000000, or preferably
200 to 100000. The number average molecular weight is calculated by
conversion based on standard polystyrene with a gel permeation
chromatography. The number average molecular weight of a material,
other than the polysiloxane containing silanol groups at both ends,
to be described later, is also calculated in the same manner as the
description above.
[0073] The silanol group equivalent in the polysiloxane containing
silanol groups at both ends is, for example, 0.002 to 25 mmol/g, or
preferably 0.02 to 25 mmol/g.
[0074] The mixing ratio of the polysiloxane containing silanol
groups at both ends with respect to 100 parts by mass of the
condensation material is, for example, 1 to 99.99 parts by mass,
preferably 50 to 99.9 parts by mass, or more preferably 80 to 99.5
parts by mass.
[0075] The ethylenic silicon compound is a silane compound having
both an ethylenically unsaturated hydrocarbon group and a leaving
group in a silanol condensation reaction and to be specific, is
represented by the following general formula (2).
[0076] General Formula (2):
R.sup.2--Si(X.sup.1).sub.3 (2)
[0077] (where, in general formula (2), R.sup.2 represents a
monovalent ethylenically unsaturated hydrocarbon group. X.sup.1
represents a halogen atom, an alkoxy group, a phenoxy group, or an
acetoxy group. X.sup.1s may be the same or different from each
other.)
[0078] In the above-described general formula (2), examples of the
ethylenically unsaturated hydrocarbon group represented by R.sup.2
include a substituted or unsubstituted ethylenically unsaturated
hydrocarbon group. Examples thereof include an alkenyl group and a
cycloalkenyl group.
[0079] An example of the alkenyl group includes an alkenyl group
having 2 to 10 carbon atoms such as a vinyl group, an allyl group,
a propenyl group, a butenyl group, a pentenyl group, a hexenyl
group, a heptenyl group, and an octenyl group.
[0080] An example of the cycloalkenyl group includes a cycloalkenyl
group having 3 to 10 carbon atoms such as a cyclohexenyl group and
a norbornenyl group.
[0081] As the ethylenically unsaturated hydrocarbon group, in view
of reactivity with a hydrosilyl group, preferably, an alkenyl group
is used, more preferably, an alkenyl group having 2 to 5 carbon
atoms is used, or particularly preferably, a vinyl group is
used.
[0082] X.sup.1 in the above-described general formula (2) is a
leaving group in the silanol condensation reaction. SiX.sup.1 group
in the above-described general formula (2) is a reactive functional
group in the silanol condensation reaction.
[0083] In the above-described general formula (2), examples of the
halogen atom represented by X.sup.1 include bromine, chlorine,
fluorine, and iodine.
[0084] In the above-described general formula (2), examples of the
alkoxy group represented by X.sup.1 include an alkoxy group
containing a straight chain or branched chain alkyl group having 1
to 6 carbon atoms (such as a methoxy group, an ethoxy group, a
propoxy group, an isopropoxy group, a butoxy group, an isobutoxy
group, a pentyloxy group, and a hexyloxy group) and an alkoxy group
containing a cycloalkyl group having 3 to 6 carbon atoms (such as a
cyclopentyloxy group and a cyclohexyloxy group).
[0085] In the above-described general formula (2), X.sup.1s may be
the same or different from each other. Preferably, X.sup.1s are the
same.
[0086] Of the X.sup.1s in the above-described general formula (2),
preferably, an alkoxy group is used, or more preferably, a methoxy
group is used.
[0087] Examples of the ethylenic silicon compound include a
trialkoxysilane containing an ethylenically unsaturated hydrocarbon
group, a trihalogenated silane containing an ethylenically
unsaturated hydrocarbon group, a triphenoxysilane containing an
ethylenically unsaturated hydrocarbon group, and a triacetoxysilane
containing an ethylenically unsaturated hydrocarbon group.
[0088] These ethylenic silicon compounds can be used alone or in
combination.
[0089] Of the ethylenic silicon compounds, preferably, a
trialkoxysilane containing an ethylenically unsaturated hydrocarbon
group is used.
[0090] To be specific, examples of the trialkoxysilane containing
an ethylenically unsaturated hydrocarbon group include a
vinyltrialkoxysilane such as a vinyltrimethoxysilane, a
vinyltriethoxysilane, and a vinyltripropoxysilane; an
allyltrimethoxysilane; a propenyltrimethoxysilane; a
butenyltrimethoxysilane; and a cyclohexenyltrimethoxysilane.
[0091] Of the trialkoxysilanes containing an ethylenically
unsaturated hydrocarbon group, preferably, a vinyltrialkoxysilane
is used, or more preferably, a vinyltrimethoxysilane is used.
[0092] The mixing ratio of the ethylenic silicon compound with
respect to 100 parts by mass of the condensation material is, for
example, 0.01 to 90 parts by mass, preferably 0.01 to 50 parts by
mass, or more preferably 0.01 to 10 parts by mass.
[0093] A commercially available product can be used as the
ethylenic silicon compound. An ethylenic silicon compound
synthesized in accordance with a known method can be also used.
[0094] The epoxy group-containing silicon compound is a silane
compound having both an epoxy group and a leaving group in a
silanol condensation reaction and to be specific, is represented by
the following general formula (3).
[0095] General Formula (3):
R.sup.3--Si(X.sup.2).sub.3 (3)
[0096] (where, in general formula (3), R.sup.3 represents a group
having an epoxy structure. X.sup.2 represents a halogen atom, an
alkoxy group, a phenoxy group, or an acetoxy group. X.sup.2s may be
the same or different from each other.)
[0097] In the above-described general formula (3), examples of the
group having an epoxy structure represented by R.sup.3 include an
epoxy group, a glycidyl ether group, and an epoxycycloalkyl group
such as an epoxycyclohexyl group.
[0098] Of the groups having an epoxy structure, preferably, a
glycidyl ether group is used. To be specific, the glycidyl ether
group is a glycidoxyalkyl group represented by the following
general formula (4).
##STR00002##
[0099] (where, in general formula (4), R.sup.4 represents a
divalent hydrocarbon group selected from a saturated hydrocarbon
group and an aromatic hydrocarbon group.)
[0100] In the above-described general formula (4), in the divalent
hydrocarbon group represented by R.sup.4, examples of the saturated
hydrocarbon group include an alkylene group having 1 to 6 carbon
atoms (such as a methylene group, an ethylene group, a propylene
group, and a butylene group) and a cycloalkylene group having 3 to
8 carbon atoms (such as a cyclopentylene group and a cyclohexylene
group).
[0101] In the above-described general formula (4), in the divalent
hydrocarbon group represented by R.sup.4, an example of the
aromatic hydrocarbon group includes an arylene group having 6 to 10
carbon atoms (such as a phenylene group and a naphthylene
group).
[0102] As the divalent hydrocarbon group, preferably, an alkylene
group having 1 to 6 carbon atoms is used, or more preferably, a
propylene group is used.
[0103] To be specific, examples of the glycidyl ether group include
a glycidoxymethyl group, a glycidoxyethyl group, a glycidoxypropyl
group, a glycidoxycyclohexyl group, and a glycidoxyphenyl
group.
[0104] Of the glycidyl ether groups, preferably, a glycidoxypropyl
group is used.
[0105] X.sup.2 in the above-described general formula (3) is a
leaving group in the silanol condensation reaction. SiX.sup.2 group
in the above-described general formula (3) is a reactive functional
group in the silanol condensation reaction.
[0106] In the above-described general formula (3), an example of
the halogen atom represented by X.sup.2 includes the same halogen
atom as that represented by X.sup.1 in the above-described general
formula (2).
[0107] In the above-described general formula (3), an example of
the alkoxy group represented by X.sup.2 includes the same alkoxy
group as that represented by X.sup.1 in the above-described general
formula (2).
[0108] In the above-described general formula (3), X.sup.2s may be
the same or different from each other. Preferably, X.sup.2s are the
same.
[0109] As X.sup.2 in the above-described general formula (3),
preferably, an alkoxy group is used, or more preferably, a methoxy
group is used.
[0110] Examples of the epoxy group-containing silicon compound
include an epoxy group-containing trialkoxysilane, an epoxy
group-containing trihalogenated silane, an epoxy group-containing
triphenoxysilane, and an epoxy group-containing
triacetoxysilane.
[0111] These epoxy group-containing silicon compounds can be used
alone or in combination.
[0112] Of the epoxy group-containing silicon compounds, preferably,
an epoxy group-containing trialkoxysilane is used.
[0113] To be specific, examples of the epoxy group-containing
trialkoxysilane include a glycidoxyalkyltrimethoxysilane such as a
glycidoxymethyltrimethoxysilane, a
(2-glycidoxyethyl)trimethoxysilane, and a
(3-glycidoxypropyl)trimethoxysilane; a
(3-glycidoxypropyl)triethoxysilane; a
(3-glycidoxypropyl)tripropoxysilane; and a
(3-glycidoxypropyl)triisopropoxysilane.
[0114] Of the epoxy group-containing trialkoxysilanes, preferably,
a glycidoxyalkyltrimethoxysilane is used, or more preferably, a
(3-glycidoxypropyl)trimethoxysilane is used.
[0115] The mixing ratio of the epoxy group-containing silicon
compound with respect to 100 parts by mass of the condensation
material is, for example, 0.01 to 90 parts by mass, preferably 0.01
to 50 parts by mass, or more preferably 0.01 to 1 parts by
mass.
[0116] A commercially available product can be used as the epoxy
group-containing silicon compound. An epoxy group-containing
silicon compound synthesized in accordance with a known method can
be also used.
[0117] The molar ratio (SiOH/(SiX.sup.1+SiX.sup.2)) of the silanol
group (the SiOH group) in the polysiloxane containing silanol
groups at both ends to the reactive functional group (the SiX.sup.1
group and the SiX.sup.2 group) in the ethylenic silicon compound
and the epoxy group-containing silicon compound is, for example,
20/1 to 0.2/1, preferably 10/1 to 0.5/1, or more preferably
substantially 1/1.
[0118] When the molar ratio exceeds the above-described upper
limit, there may be a case where a material in a semi-cured state
(a first-step cured material) having an appropriate toughness is
not obtained when the second condensation reaction and addition
reaction curable type silicone resin composition is brought into a
semi-cured state. On the other hand, when the molar ratio is below
the above-described lower limit, there may be a case where the
mixing proportion of the ethylenic silicon compound and the epoxy
group-containing silicon compound is excessively large, so that the
heat resistance of the transparent layer 2 to be obtained is
reduced.
[0119] When the molar ratio is within the above-described range
(preferably, substantially 1/1), the silanol group (the SiOH group)
in the polysiloxane containing silanol groups at both ends, and the
reactive functional group (the SiX.sup.1 group) in the ethylenic
silicon compound and the reactive functional group (the SiX.sup.2
group) in the epoxy group-containing silicon compound can be
subjected to a condensation reaction neither too much nor too
little.
[0120] The molar ratio of the ethylenic silicon compound to the
epoxy group-containing silicon compound is, for example, 10/90 to
99/1, preferably 50/50 to 97/3, or more preferably 80/20 to
95/5.
[0121] When the molar ratio is within the above-described range,
there is an advantage that the adhesive properties of a cured
material (a two-step cured material) can be improved, while the
strength thereof is ensured.
[0122] The organohydrogensiloxane is an organosiloxane having, in
one molecule, at least two hydrosilyl groups without containing an
ethylenically unsaturated hydrocarbon group.
[0123] To be specific, examples of the organohydrogensiloxane
include an organopolysiloxane containing a hydrogen atom in its
side chain and an organopolysiloxane containing hydrogen atoms at
both ends.
[0124] The organopolysiloxane containing a hydrogen atom in its
side chain is an organohydrogensiloxane having a hydrogen atom as a
side chain that branches off from the main chain. Examples thereof
include a methylhydrogenpolysiloxane, a
dimethylpolysiloxane-co-methylhydrogenpolysiloxane, an
ethylhydrogenpolysiloxane, and a
methylhydrogenpolysiloxane-co-methylphenylpolysiloxane.
[0125] The number average molecular weight of the
organopolysiloxane containing a hydrogen atom in its side chain is,
for example, 100 to 1000000.
[0126] The organopolysiloxane containing hydrogen atoms at both
ends is an organohydrogensiloxane having hydrogen atoms at both
ends of the main chain. Examples thereof include a
polydimethylsiloxane containing hydrosilyl groups at both ends, a
polymethylphenylsiloxane containing hydrosilyl groups at both ends,
and a polydiphenylsiloxane containing hydrosilyl groups at both
ends.
[0127] The number average molecular weight of the
organopolysiloxane containing hydrogen atoms at both ends is, for
example, in view of stability and/or handling ability, 100 to
1000000, or preferably 100 to 100000.
[0128] These organohydrogensiloxanes can be used alone or in
combination.
[0129] Of the organohydrogensiloxanes, preferably, an
organopolysiloxane containing a hydrogen atom in its side chain is
used, or more preferably, a
dimethylpolysiloxane-co-methylhydrogenpolysiloxane is used.
[0130] The viscosity of the organohydrogensiloxane at 25.degree. C.
is, for example, 10 to 100000 mPas, or preferably 20 to 50000 mPas.
The viscosity is measured with an E-type viscometer (type of rotor:
1''34'.times.R24, a number of revolutions of 10 rpm). The viscosity
of the material or the composition, other than the
organohydrogensiloxane, to be described later is also calculated in
the same manner as described above.
[0131] The hydrosilyl group equivalent in the
organohydrogensiloxane is, for example, 0.1 to 30 mmol/g, or
preferably 1 to 20 mmol/g.
[0132] A commercially available product can be used as the
organohydrogensiloxane. An organohydrogensiloxane synthesized in
accordance with a known method can be also used.
[0133] The mixing ratio of the organohydrogensiloxane with respect
to 100 parts by mass of the ethylenic silicon compound is, though
depending on the molar ratio of the ethylenically unsaturated
hydrocarbon group (R.sup.2 in the above-described general formula
(2)) in the ethylenic silicon compound to the hydrosilyl group (the
SiH group) in the organohydrogensiloxane, for example, 10 to 10000
parts by mass, or preferably 100 to 1000 parts by mass.
[0134] The molar ratio (R.sup.2/SiH) of the ethylenically
unsaturated hydrocarbon group (R.sup.2 in the above-described
general formula (2)) in the ethylenic silicon compound to the
hydrosilyl group (the SiH group) in the organohydrogensiloxane is,
for example, 20/1 to 0.05/1, preferably 20/1 to 0.1/1, more
preferably 10/1 to 0.1/1, particularly preferably 10/1 to 0.2/1, or
most preferably 5/1 to 0.2/1. The molar ratio thereof can be also
set to be, for example, less than 1/1 and not less than 0.05/1.
[0135] When the molar ratio exceeds 20/1, there may be a case where
a semi-cured material (a first-step cured material) having an
appropriate toughness is not obtained when the second condensation
reaction and addition reaction curable type silicone resin
composition is brought into a semi-cured state. On the other hand,
when the molar ratio is below 0.05/1, there may be a case where the
mixing proportion of the organohydrogensiloxane is excessively
large, so that the heat resistance and the toughness of the
transparent layer 2 to be obtained are insufficient.
[0136] When the molar ratio is less than 1/1 and not less than
0.05/1, in allowing the second condensation reaction and addition
reaction curable type silicone resin composition to be brought into
a semi-cured state, the second condensation reaction and addition
reaction curable type silicone resin composition can be quickly
transferred into a semi-cured state with respect to the second
condensation reaction and addition reaction curable type silicone
resin composition whose molar ratio is 20/1 to 1/1.
[0137] The condensation catalyst is not particularly limited as
long as it is a substance capable of improving the reaction rate of
the condensation reaction of the silanol group with the reactive
functional group (the SiX.sup.1 group in the above-described
general formula (2) and the SiX.sup.2 group in the above-described
general formula (3)). Examples of the condensation catalyst include
an acid such as hydrochloric acid, acetic acid, formic acid, and
sulfuric acid; a base such as potassium hydroxide, sodium
hydroxide, potassium carbonate, and tetramethylammonium hydroxide;
and a metal such as aluminum, titanium, zinc, and tin.
[0138] These condensation catalysts can be used alone or in
combination.
[0139] Of the condensation catalysts, in view of compatibility and
thermal decomposition properties, preferably, a base is used, or
more preferably, tetramethylammonium hydroxide is used.
[0140] The mixing ratio of the condensation catalyst with respect
to 100 mol of the polysiloxane containing silanol groups at both
ends is, for example, 0.1 to 50 mol, or preferably 0.5 to 5
mol.
[0141] The addition catalyst is not particularly limited as long as
it is a substance (a hydrosilylation catalyst) capable of improving
the reaction rate of the addition reaction, that is, the
hydrosilylation reaction of the ethylenically unsaturated
hydrocarbon group with the SiH group. An example thereof includes a
metal catalyst such as a platinum catalyst including platinum
black, platinum chloride, chloroplatinic acid, a platinum olefin
complex (for example, a platinum-divinylsiloxane complex and the
like), a platinum carbonyl complex, and platinum acetyl acetate; a
palladium catalyst; and a rhodium catalyst.
[0142] These addition catalysts can be used alone or in
combination.
[0143] Of the addition catalysts, in view of compatibility,
transparency, and catalyst activity, preferably, a platinum
catalyst is used, or more preferably, a platinum carbonyl complex
is used.
[0144] The mixing ratio of the addition catalyst, as a number of
parts by mass of the metal amount in the addition catalyst, with
respect to 100 parts by mass of the organohydrogensiloxane is, for
example 1.0.times.10.sup.-4 to 1.0 parts by mass, preferably
1.0.times.10.sup.-4 to 0.5 parts by mass, or more preferably
1.0.times.10.sup.-4 to 0.05 parts by mass.
[0145] As the above-described catalyst, a catalyst in a solid state
can be used as it is. Alternatively, in view of handling ability, a
catalyst can be also used as a solution or as a dispersion liquid
dissolved or dispersed in a solvent.
[0146] An example of the solvent includes an organic solvent such
as an alcohol including methanol and ethanol; a silicon compound
including siloxane; an aliphatic hydrocarbon including hexane; an
aromatic hydrocarbon including toluene; and ether including
tetrahydrofuran (THF). Also, an example of the solvent includes an
aqueous solvent such as water.
[0147] As the solvent, when the catalyst is a condensation
catalyst, preferably, an alcohol is used and when the catalyst is
an addition catalyst, preferably, a silicon compound and an
aromatic hydrocarbon are used.
[0148] The above-described polysiloxane containing silanol groups
at both ends, ethylenic silicon compound, epoxy group-containing
silicon compound, and organohydrogensiloxane are blended with
catalysts (the condensation catalyst and the addition catalyst) to
be stirred and mixed, so that the second condensation reaction and
addition reaction curable type silicone resin composition is
prepared.
[0149] In order to prepare the second condensation reaction and
addition reaction curable type silicone resin composition, for
example, the above-described materials (the condensation materials
and the addition materials) and the catalysts can be blended
simultaneously. Alternatively, each of the materials and each of
the catalysts can be added, respectively, at different timings.
Furthermore, a part of the components can be added simultaneously
and each of the remaining components can be added, respectively, at
different timings.
[0150] Of the preparing methods of the second condensation reaction
and addition reaction curable type silicone resin composition,
preferably, the following method is used. The condensation
materials and the condensation catalyst are first added
simultaneously. Next, the addition material is added thereto and
thereafter, the addition catalyst is added thereto.
[0151] To be specific, the polysiloxane containing silanol groups
at both ends, the ethylenic silicon compound, and the epoxy
group-containing silicon compound (that is, the condensation
materials) are simultaneously blended with the condensation
catalyst at the above-described proportion to be stirred for, for
example, 5 minutes to 24 hours.
[0152] At the time of blending and stirring, the temperature can be
also adjusted to be, for example, 0 to 60.degree. C., or preferably
10 to 40.degree. C. so as to improve the compatibility and the
handling ability of the condensation materials.
[0153] Thereafter, the pressure in the system (the above-described
mixture) is reduced as required, so that a volatile component (an
organic solvent) is removed.
[0154] Next, the organohydrogensiloxane is blended into the
obtained mixture of the condensation materials and the condensation
catalyst to be stirred for, for example, 1 to 120 minutes.
[0155] At the time of blending and stirring, the temperature can be
also adjusted to be, for example, 0 to 60.degree. C. so as to
improve the compatibility and the handling ability of the mixture
and the organohydrogensiloxane.
[0156] Thereafter, the addition catalyst is blended into the system
(the above-described mixture) to be stirred for, for example, 1 to
60 minutes.
[0157] In this way, the second condensation reaction and addition
reaction curable type silicone resin composition can be
prepared.
[0158] The prepared second condensation reaction and addition
reaction curable type silicone resin composition is, for example,
in a liquid state (in an oil state) at normal temperature.
[0159] The viscosity of the second condensation reaction and
addition reaction curable type silicone resin composition at
25.degree. C. is, for example, 1000 to 50000 mPas, or preferably
4000 to 20000 mPas.
[0160] To be specific, the first condensation reaction and addition
reaction curable type silicone resin composition is described in
Japanese Unexamined Patent Publication No. 2010-285593 or the like
and contains, for example, a polysiloxane containing silanol groups
at both ends, a vinyltrimethoxysilane, an organohydrogensiloxane,
tetramethylammonium hydroxide, and a platinum carbonyl complex. The
second condensation reaction and addition reaction curable type
silicone resin composition is described in Japanese Unexamined
Patent Publication No. 2010-265436 or the like and contains, for
example, a polydimethylsiloxane containing silanol groups at both
ends, a vinyltrimethoxysilane, a
(3-glycidoxypropyl)trimethoxysilane, an organohydrogensiloxane,
tetramethylammonium hydroxide, and a platinum complex. The third
condensation reaction and addition reaction curable type silicone
resin composition is described in Japanese Unexamined Patent
Publication No. 2011-149020 or the like and contains, for example,
a silicone oil containing silanol groups at both ends, a
vinyldimethoxymethylsilane, an organohydrogensiloxane,
tetramethylammonium hydroxide, and a platinum carbonyl complex.
[0161] The fourth condensation reaction and addition reaction
curable type silicone resin composition is described in Japanese
Unexamined Patent Publication No. 2011-219597 or the like and
contains, for example, a dimethylvinylsilyl-terminated
polydimethylsiloxane, a trimethylsilyl-terminated
dimethylsiloxane-methylhydrosiloxane copolymer, a
platinum-divinyltetramethyldisiloxane complex, and
tetramethylammonium hydroxide. The fifth condensation reaction and
addition reaction curable type silicone resin composition contains,
for example, a hydrogen-terminated
vinylmethylsiloxane-dimethylsiloxane copolymer, a
trimethylsiloxy-terminated dimethylsiloxane-methylhydrosiloxane
copolymer, a platinum carbonyl complex, and tetramethylammonium
hydroxide. The sixth condensation reaction and addition reaction
curable type silicone resin composition contains, for example, a
hydroxy-terminated vinylmethylsiloxane-dimethylsiloxane copolymer,
a trimethylsiloxy-terminated dimethylsiloxane-methylhydrosiloxane
copolymer, a platinum carbonyl complex, and tetramethylammonium
hydroxide.
[0162] The seventh condensation reaction and addition reaction
curable type silicone resin composition is described in Japanese
Unexamined Patent Publication No. 2009-127021 or the like and
contains, for example, a silicone oil containing silanol groups at
both ends and triisopropyl borate. The eighth condensation reaction
and addition reaction curable type silicone resin composition is
described in Japanese Unexamined Patent Publication No. 2009-235376
or the like and contains, for example, a methacrylic silane
coupling agent and a polyaluminosiloxane.
[0163] The condensation reaction and addition reaction curable type
silicone resin composition is, for example, in a liquid state (in
an oil state) at normal temperature and is heated, as described
later, so that a condensation material therein is subjected to a
condensation reaction to be brought into a B-stage state. That is,
the condensation reaction and addition reaction curable type
silicone resin composition is brought into a first-step cured
material.
[0164] Thereafter, the condensation reaction and addition reaction
curable type silicone resin composition in a B-stage state is
further heated, so that an addition material therein is subjected
to an addition reaction to be brought into a C-stage state (a final
curing state). That is, the condensation reaction and addition
reaction curable type silicone resin composition is brought into a
two-step cured material.
[0165] An example of the one-step curable type silicone resin
composition includes an addition reaction curable type silicone
resin composition.
[0166] The addition reaction curable type silicone resin
composition contains, for example, a polysiloxane containing an
ethylenically unsaturated hydrocarbon group which serves as a main
agent and an organohydrogensiloxane which serves as a cross-linking
agent.
[0167] The polysiloxane containing an ethylenically unsaturated
hydrocarbon group is a liquid polysiloxane which contains
ethylenically unsaturated hydrocarbon groups at both ends or
contains an ethylenically unsaturated hydrocarbon group in its side
chain.
[0168] An example of the ethylenically unsaturated hydrocarbon
group includes the above-described ethylenically unsaturated
hydrocarbon group. Preferably, an alkenyl group is used, or more
preferably, a vinyl group is used.
[0169] Examples of the polysiloxane containing an ethylenically
unsaturated hydrocarbon group include an alkenyl group-containing
polydimethylsiloxane, an alkenyl group-containing
polymethylphenylsiloxane, and an alkenyl group-containing
polydiphenylsiloxane.
[0170] These polysiloxanes containing an ethylenically unsaturated
hydrocarbon group can be used alone or in combination.
[0171] An example of the organohydrogensiloxane includes the same
organohydrogensiloxane as that described above.
[0172] These organohydrogensiloxanes can be used alone or in
combination.
[0173] In the addition reaction curable type silicone resin
composition, the polysiloxane containing an ethylenically
unsaturated hydrocarbon group and the organohydrogensiloxane are
usually provided in separate packages. To be specific, the addition
reaction curable type silicone resin composition is provided as two
liquids of A liquid which contains a main agent (the polysiloxane
containing an ethylenically unsaturated hydrocarbon group) and B
liquid which contains a cross-linking agent (the
organohydrogensiloxane). A known catalyst which is necessary for
the addition reaction of both components is added in the
polysiloxane containing an ethylenically unsaturated hydrocarbon
group.
[0174] As the addition reaction curable type silicone resin
composition, a commercially available product (trade name:
KER-2500, manufactured by Shin-Etsu Chemical Co., Ltd., trade name:
LR-7665, manufactured by Asahikasei Silicone Co., Ltd.) can be
used.
[0175] In the addition reaction curable type silicone resin
composition, the main agent (A liquid) and the cross-linking agent
(B liquid) are mixed to prepare a liquid mixture. In a step of
forming the liquid mixture into the above-described shape of the
transparent layer 2, the polysiloxane containing an ethylenically
unsaturated hydrocarbon group and the organohydrogensiloxane are
subjected to an addition reaction and the addition reaction curable
type silicone resin composition is cured, so that a silicone
elastomer (a cured material) is formed.
[0176] The first silicone resin composition is, for example,
prepared from a thermosetting silicone resin composition before
final curing or after final curing. Preferably, in view of
improving the adhesive properties of the transparent layer 2 to the
board 12 (ref: FIGS. 6 (b) and 7), the first silicone resin
composition is prepared from a thermosetting silicone resin
composition before final curing.
[0177] More preferably, when the thermosetting silicone resin
composition is a two-step curable type silicone resin composition,
the first silicone resin composition is a first-step cured material
of the two-step curable type silicone resin composition and when
the thermosetting silicone resin composition is a one-step curable
type silicone resin composition, the first silicone resin
composition is an uncured material (before curing) of the one-step
curable type silicone resin composition.
[0178] Particularly preferably, the thermosetting silicone resin
composition is formed as a first-step cured material of the
two-step curable type silicone resin composition.
[0179] The mixing ratio of the first silicone resin composition
with respect to a transparent composition is, for example, 50 mass
% or more, or preferably 80 mass % or more, and is also 100 mass %
or less.
[0180] A filler can be contained in the transparent composition as
required.
[0181] Examples of the filler include silicone microparticles,
glass, alumina, silica (fused silica, crystalline silica, ultrafine
amorphous silica, hydrophobic ultrafine silica, and the like),
titania, zirconia, talc, clay, and barium sulfate. These fillers
can be used alone or in combination of two or more.
[0182] Preferably, silicone microparticles and silica are used.
[0183] The particle size of the filler is appropriately selected in
accordance with its purpose and use. The average particle size (the
average of the maximum length) thereof is, in view of transparency,
for example, 20 .mu.m or less, or preferably 10 .mu.m or less.
[0184] The content ratio of the filler with respect to 100 parts by
mass of the first silicone resin composition is, for example, 0.1
to 80 parts by mass, or preferably 1 to 50 parts by mass.
[0185] In addition, a known additive can be added to the
transparent composition at an appropriate proportion. Examples of
the known additive include modifiers, surfactants, dyes, pigments,
discoloration inhibitors, and ultraviolet absorbers.
[0186] As shown in FIG. 1, the phosphor encapsulating layers 3 fill
the concave portions 4. The upper surfaces of the phosphor
encapsulating layers 3 are formed so as to be flush with the upper
surface of the transparent layer 2 around the concave portions 4 in
the plane direction. The size of each of the phosphor encapsulating
layers 3 is set corresponding to the size of each of the concave
portions 4.
[0187] The phosphor encapsulating layers 3 are formed from a
phosphor encapsulating composition which contains a phosphor and a
second silicone resin composition.
[0188] An example of the phosphor includes a yellow phosphor which
is capable of converting blue light into yellow light. An example
of the phosphor includes a phosphor obtained by doping a metal atom
such as cerium (Ce) or europium (Eu) into a composite metal oxide,
a metal sulfide, or the like.
[0189] To be specific, examples of the phosphor include a garnet
type phosphor having a garnet type crystal structure such as
Y.sub.3Al.sub.5O.sub.12:Ce (YAG (yttrium aluminum garnet):Ce), (Y,
Gd).sub.3Al.sub.5O.sub.12:Ce, Tb.sub.3Al.sub.3O.sub.12:Ce,
Ca.sub.3Sc.sub.2Si.sub.3O.sub.12:Ce, and Lu.sub.2CaMg.sub.2(Si,
Ge).sub.3O.sub.12:Ce; a silicate phosphor such as (Sr,
Ba).sub.2SiO.sub.4:Eu, Ca.sub.3SiO.sub.4Cl.sub.2:Eu,
Sr.sub.3SiO.sub.5:Eu, Li.sub.2SrSiO.sub.4:Eu, and
Ca.sub.3Si.sub.2O.sub.7:Eu; an aluminate phosphor such as
CaAl.sub.12O.sub.19:Mn and SrAl.sub.2O.sub.4:Eu; a sulfide phosphor
such as ZnS:Cu,Al, CaS:Eu, CaGa.sub.2S.sub.4:Eu, and
SrGa.sub.2S.sub.4:Eu; an oxynitride phosphor such as
CaSi.sub.2O.sub.2N.sub.2:Eu, SrSi.sub.2O.sub.2N.sub.2:Eu,
BaSi.sub.2O.sub.2N.sub.2:Eu, and Ca-.alpha.-SiAlON; a nitride
phosphor such as CaAlSiN.sub.3:Eu and CaSi.sub.5N.sub.8:Eu; and a
fluoride-based phosphor such as K.sub.2SiF.sub.6:Mn and
K.sub.2TiF.sub.6:Mn. Preferably, a garnet type phosphor is used, or
more preferably, Y.sub.3Al.sub.5O.sub.12:Ce is used.
[0190] The phosphor is in the form of a particle. The shape thereof
is not particularly limited and examples of the shape thereof
include a generally sphere shape, a generally flat plate shape, and
a generally needle shape.
[0191] The average particle size (the average of the maximum
length) of the phosphor is, for example, 0.1 to 30 .mu.m, or
preferably 0.2 to 20 .mu.m. The average particle size of the
phosphor particles is measured with a particle size distribution
analyzer.
[0192] These phosphors can be used alone or in combination.
[0193] The mixing ratio of the phosphor with respect to 100 parts
by mass of the second silicone resin composition is, for example,
0.1 to 80 parts by mass, or preferably 1 to 60 parts by mass.
[0194] An example of the second silicone resin composition includes
a thermosetting silicone resin composition such as a two-step
curable type silicone resin composition and a silicone resin
composition having both thermoplastic properties and thermosetting
properties (hereinafter, defined as a silicone resin composition
having both thermoplastic and thermosetting properties).
[0195] An example of the two-step curable type silicone resin
composition includes the same two-step curable type silicone resin
composition as that illustrated in the first silicone resin
composition. Preferably, a first-step cured material of the
two-step curable type silicone resin composition is used.
[0196] The silicone resin composition having both thermoplastic and
thermosetting properties is a thermosetting silicone resin
composition which is once plasticized (or liquefied) by heating and
thereafter, is cured by further heating.
[0197] Examples of the silicone resin composition having both
thermoplastic and thermosetting properties include a first silicone
resin composition having both thermoplastic and thermosetting
properties which contains a silicone resin containing amino groups
at both ends, an organohydrogensiloxane, a diisocyanate, and a
hydrosilylation catalyst; a second silicone resin composition
having both thermoplastic and thermosetting properties which
contains a silicone resin containing amino groups at both ends, a
diisocyanate, and a radical generator; a third silicone resin
composition having both thermoplastic and thermosetting properties
which contains a cage octasilsesquioxane having a hydrosilyl group,
an alkenyl group-containing polysiloxane which contains an alkenyl
group having a number of moles smaller than that of a hydrosilyl
group in the cage octasilsesquioxane, and a hydrosilylation
catalyst; a fourth silicone resin composition having both
thermoplastic and thermosetting properties which contains a cage
octasilsesquioxane having a hydrosilyl group, an alkenyl
group-containing polysiloxane which contains an alkenyl group
having a number of moles smaller than that of a hydrosilyl group in
the cage octasilsesquioxane, a hydrosilylation catalyst, and a
hydroxyl group-containing polysiloxane; a fifth silicone resin
composition having both thermoplastic and thermosetting properties
which contains a cage octasilsesquioxane having a hydrosilyl group,
an alkenyl group-containing polysiloxane which contains an alkenyl
group having a number of moles smaller than that of a hydrosilyl
group in the cage octasilsesquioxane, a hydrosilylation catalyst,
and an organohydrogenpolysiloxane; and a sixth silicone resin
composition having both thermoplastic and thermosetting properties
which contains a cage octasilsesquioxane, a straight chain
polysiloxane containing alkenyl groups at both ends which contains
alkenyl groups having a number of moles smaller than that of a
hydrosilyl group in the cage octasilsesquioxane at both ends of a
molecule, a hydrosilylation catalyst, and a polysiloxane containing
alkenyl groups in its side chain which has two or more alkenyl
groups in its side chain.
[0198] These silicone resin compositions having both thermoplastic
and thermosetting properties can be used alone or in
combination.
[0199] As the silicone resin composition having both thermoplastic
and thermosetting properties, preferably, a sixth silicone resin
composition having both thermoplastic and thermosetting properties
is used.
[0200] In the sixth silicone resin composition having both
thermoplastic and thermosetting properties, the cage
octasilsesquioxane is an octamer of trifunctional silicone monomer
and to be specific, has eight groups represented by the following
formula (5),
##STR00003##
[0201] (where, in formula, R.sup.5 represents a monovalent
hydrocarbon group and R.sup.6 represents hydrogen or a monovalent
hydrocarbon group. The molar ratio of the monovalent hydrocarbon
group: hydrogen in R.sup.6 in the cage octasilsesquioxane as a
whole is, as an average value, in the range of 6.5:1.5 to
5.5:2.5.)
[0202] To be more specific, the cage octasilsesquioxane is
represented by the following formula (6).
##STR00004##
[0203] (where, in formula, R.sup.5 and R.sup.6 are the same as
described above. The molar ratio of the monovalent hydrocarbon
group: hydrogen in R.sup.6 is the same as described above.)
[0204] In the above-described formulas (5) and (6), an example of
the monovalent hydrocarbon group represented by R.sup.5 includes
the same monovalent hydrocarbon group as that illustrated by
R.sup.1 in the above-described formula (1).
[0205] In the above-described formulas (5) and (6), an example of
the monovalent hydrocarbon group represented by R.sup.6 includes
the same monovalent hydrocarbon group as that represented by
R.sup.5 described above. Preferably, methyl is used.
[0206] The molar ratio of the monovalent hydrocarbon group:
hydrogen in R.sup.6 in formula (6), in the cage octasilsesquioxane
as a whole, is in the range of 6.5:1.5 to 5.5:2.5, or preferably
6.0:2.0 to 5.5:2.5 as an average value.
[0207] That is, in one molecule of the cage octasilsesquioxane, the
group represented by the above-described formula (5) forms 1.5 to
2.5 (to be specific, two), or preferably 2 to 2.5 (to be specific,
two) of the hydrosilyl groups (--SiH).
[0208] When the above-described molar ratio of the monovalent
hydrocarbon group: hydrogen in R.sup.6 exceeds 6.5/1.5 (=6.5:1.5)
(for example, 7/1 (=7:1)), the number of moles of the hydrosilyl
group is excessively small, so that the reactivity of the cage
octasilsesquioxane with respect to the polysiloxane containing
alkenyl groups at both ends (and the polysiloxane containing
alkenyl groups in its side chain) is significantly reduced and the
molecular weight of the sixth silicone resin composition having
both thermoplastic and thermosetting properties to be obtained is
reduced. Therefore, there may be a case where the sixth silicone
resin composition having both thermoplastic and thermosetting
properties in a solid state cannot be obtained.
[0209] On the other hand, when the above-described molar ratio of
the monovalent hydrocarbon group: hydrogen in R.sup.6 is below
5.5/2.5 (=5.5:2.5) (for example, 5/3 (=5:3)), the number of moles
of the hydrosilyl group in the cage octasilsesquioxane is
excessively large, so that the reactivity of the cage
octasilsesquioxane with respect to the polysiloxane containing
alkenyl groups at both ends (and the polysiloxane containing
alkenyl groups in its side chain) is significantly increased.
Therefore, the sixth silicone resin composition having both
thermoplastic and thermosetting properties may not show the
thermoplastic properties.
[0210] To be specific, an example of the above-described cage
octasilsesquioxane includes a cage octasilsesquioxane having methyl
in R.sup.5 and methyl or hydrogen in R.sup.6 in the above-described
formulas (5) and (6) and having a molar ratio of methyl: hydrogen
in R.sup.6 in the cage octasilsesquioxane as a whole of 5.5:2.5,
6:2, or 6.5:1.5 as an average value.
[0211] The cage octasilsesquioxane represented by the
above-described formula (6) is synthesized by, for example, a known
method (for example, in conformity with the description in Japanese
Unexamined Patent Publication No. 2007-246880).
[0212] To be specific, tetraalkoxysilane (tetraethoxysilane or the
like) is allowed to react with an alcohol such as methanol and/or
water in the presence of a catalyst to synthesize an
octa(silsesquioxane) skeleton (a portion in formula (6) excluding
the groups in formula (5)) and thereafter, dialkylchlorosilane
(dimethylchlorosilane or the like) and trialkylchlorosilane
(trimethylchlorosilane or the like) are blended at a mixing
proportion corresponding to the above-described molar ratio of the
monovalent hydrocarbon group: hydrogen in R.sup.6, so that an
alkoxyl group (ethoxy or the like) bonded to a silicon atom of the
octa(silsesquioxane) skeleton is allowed to react with the
dialkylchlorosilane and the trialkylchlorosilane. After the
reaction, a reacting product is refined as required. In this way,
the cage octasilsesquioxane can be obtained.
[0213] A commercially available product can be also used as the
cage octasilsesquioxane.
[0214] The polysiloxane containing alkenyl groups at both ends is a
straight chain polysiloxane which contains alkenyl groups at both
ends of a molecule. To be specific, the polysiloxane containing
alkenyl groups at both ends is represented by the following formula
(7).
##STR00005##
[0215] (where, in formula, R.sup.7 represents a monovalent
hydrocarbon group. R.sup.8 represents an alkenyl group. "a"
represents an integer of 1 or more.)
[0216] The monovalent hydrocarbon groups represented by R.sup.7 in
formula (7) may be the same or different from each other.
Preferably, the monovalent hydrocarbon groups represented by
R.sup.7 are the same.
[0217] An example of the monovalent hydrocarbon group represented
by R.sup.7 includes the same monovalent hydrocarbon group as that
represented by R.sup.5 in the above-described formulas (5) and (6).
Preferably, methyl and phenyl are used, or more preferably, methyl
is used.
[0218] Examples of the alkenyl group represented by R.sup.8 in
formula (7) include a substituted or unsubstituted alkenyl group.
Preferably, an unsubstituted alkenyl group is used.
[0219] An example of the alkenyl group includes an alkenyl group
having 2 to 10 carbon atoms such as vinyl, allyl, propenyl,
butenyl, and pentenyl.
[0220] The number of carbon atoms of the alkenyl group is, for
example, 2 to 10, or preferably 2 to 5.
[0221] R.sup.8s may be the same or different from each other.
Preferably, R.sup.8s are the same.
[0222] As the alkenyl group, preferably, in view of reactivity with
the hydrosilyl group in the cage octasilsesquioxane, an alkenyl
group having 2 to 5 carbon atoms is used, or more preferably, vinyl
is used.
[0223] "a" represents, in view of reactivity and stability,
preferably an integer of 1 to 100, or more preferably an integer of
1 to 50.
[0224] The number average molecular weight of the polysiloxane
containing alkenyl groups at both ends is, in view of stability and
handling ability, for example, 100 to 8000, or preferably 300 to
5000.
[0225] The polysiloxane containing alkenyl groups at both ends is
synthesized in accordance with, for example, a known method. A
commercially available product (for example, manufactured by
Gelest, Inc.) can be also used.
[0226] Examples of the hydrosilylation catalyst include a platinum
catalyst such as platinum black, platinum chloride, chloroplatinic
acid, a platinum olefin complex, a platinum carbonyl complex, and
platinum acetyl acetate; a palladium catalyst; and a rhodium
catalyst.
[0227] Of the hydrosilylation catalysts, preferably, in view of
compatibility and transparency, a platinum catalyst is used, or
more preferably, a platinum olefin complex is used. To be specific,
a platinum-divinylsiloxane complex such as a
platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex is
used.
[0228] The hydrosilylation catalyst may be prepared as a solution
in a known solvent (such as toluene).
[0229] The polysiloxane containing alkenyl groups in its side chain
is a polysiloxane which contains two or more alkenyl groups in its
side chain. Examples of the polysiloxane containing alkenyl groups
in its side chain include a straight chain siloxane-containing
polysiloxane (a straight chain polysiloxane) which contains alkenyl
groups as a side chain bonded to the main chain (a silicon atom
thereof) that contains a straight chain siloxane portion
(--Si--O--) and/or a branched chain siloxane-containing
polysiloxane (a branched chain polysiloxane) which contains alkenyl
groups bonded to the silicon atoms in branched chain siloxane
portions.
[0230] To be specific, the straight chain siloxane-containing
polysiloxane is represented by the following formula (8).
##STR00006##
[0231] (where, in formula, A to D represent a constituent unit, A
and D represent an end unit, and B and C represent a repeating
unit. R.sup.9 represents a monovalent hydrocarbon group and
R.sup.10 represents an alkenyl group. "b" represents an integer of
0 or 1 or more and "c" represents an integer of 2 or more.)
[0232] A to D constitute a straight chain siloxane-containing
polysiloxane.
[0233] The monovalent hydrocarbon groups represented by R.sup.9 in
formula (8) may be the same or different from each other.
Preferably, the monovalent hydrocarbon groups represented by
R.sup.9 are the same.
[0234] An example of the monovalent hydrocarbon group represented
by R.sup.9 includes the same monovalent hydrocarbon group as that
represented by R.sup.5 in the above-described formulas (5) and (6).
Preferably, methyl and phenyl are used, or more preferably, methyl
is used.
[0235] "b" represents, in view of reactivity and stability,
preferably an integer of 1 to 10000, or more preferably an integer
of 1 to 5000.
[0236] "c" represents, in view of reactivity and stability,
preferably an integer of 2 to 500, more preferably an integer of 2
to 100.
[0237] The number average molecular weight of the straight chain
siloxane-containing polysiloxane is, in view of stability and
handling ability, for example, 200 to 1000000, or preferably 200 to
80000.
[0238] The content of the alkenyl group in the straight chain
siloxane-containing polysiloxane is, for example, 0.01 to 10
mmol/g, or preferably 0.1 to 5 mmol/g. The content of the alkenyl
group in the straight chain siloxane-containing polysiloxane is
calculated by the area proportion of the alkenyl group to the
methyl group with a .sup.1H-NMR.
[0239] The straight chain siloxane-containing polysiloxane is
synthesized in accordance with, for example, a known method. A
commercially available product (for example, manufactured by
Gelest, Inc.) can be also used.
[0240] To be specific, the branched chain siloxane-containing
polysiloxane is represented by the following formula (9).
##STR00007##
[0241] (where, in formula, E to H represent a constituent unit, E
to G represent a repeating unit, and H represents an end unit.
R.sup.11 represents a monovalent hydrocarbon group. "e" represents
an integer of 1 or more, "f" and "g" represent an integer of 0 or
more, and "h" represents an integer of 4 or more. Furthermore, at
least one R.sup.11 per one molecule is an alkenyl group.)
[0242] E to H constitute a branched chain siloxane-containing
polysiloxane.
[0243] The monovalent hydrocarbon group represented by R.sup.11 is,
for example, a saturated hydrocarbon group, an aromatic hydrocarbon
group, or an unsaturated hydrocarbon group (excluding an aromatic
hydrocarbon group).
[0244] An example of the saturated hydrocarbon group and the
aromatic hydrocarbon group includes the same monovalent hydrocarbon
group as that represented by R.sup.5 in the above-described
formulas (5) and (6). Preferably, methyl and phenyl are used, or
more preferably, methyl is used.
[0245] An example of the unsaturated hydrocarbon group (excluding
the aromatic hydrocarbon group) includes the same alkenyl group as
that represented by R.sup.8 in the above-described formula (7).
Preferably, vinyl is used.
[0246] The monovalent hydrocarbon group represented by R.sup.11 in
formula (9) contains at least an alkenyl group, preferably contains
an alkyl group and an alkenyl group, or more preferably contains a
methyl group and a vinyl group.
[0247] The number of the alkenyl group in the branched chain
siloxane-containing polysiloxane is 1 or more, or preferably 3 or
more, and is usually 30 or less.
[0248] "e" represents preferably an integer of 1 to 100, or more
preferably an integer of 1 to 50.
[0249] "f" represents preferably an integer of 1 to 100, or more
preferably an integer of 1 to 50.
[0250] "g" represents preferably an integer of 1 to 100, or more
preferably an integer of 1 to 50.
[0251] "h" represents preferably an integer of 1 to 100, or more
preferably an integer of 1 to 30.
[0252] The number average molecular weight of the branched chain
siloxane-containing polysiloxane is, in view of stability and
handling ability, for example, 100 to 10000, or preferably 200 to
8000.
[0253] The content of the alkenyl group in the branched chain
siloxane-containing polysiloxane is, for example, 0.01 to 100
mmol/g, or preferably 0.1 to 10 mmol/g. The content of the alkenyl
group in the branched chain siloxane-containing polysiloxane is
calculated by the area proportion of the alkenyl group to the
methyl group with a .sup.1H-NMR.
[0254] The branched chain siloxane-containing polysiloxane is
synthesized in accordance with, for example, a known method. A
commercially available product (for example, manufactured by
Gelest, Inc.) can be also used.
[0255] The cage octasilsesquioxane, the polysiloxane containing
alkenyl groups at both ends, the hydrosilylation catalyst, and the
polysiloxane containing alkenyl groups in its side chain are
blended, so that the sixth silicone resin composition having both
thermoplastic and thermosetting properties is prepared.
[0256] The mixing ratio of the cage octasilsesquioxane with respect
to the sixth silicone resin composition having both thermoplastic
and thermosetting properties is, for example, 10 to 80 mass %, or
preferably 10 to 70 mass %.
[0257] The mixing proportion of the polysiloxane containing alkenyl
groups at both ends is adjusted so that the number of moles of the
alkenyl group in the polysiloxane containing alkenyl groups at both
ends is smaller than that of the hydrosilyl group in the cage
octasilsesquioxane.
[0258] That is, the molar ratio (the number of moles of the alkenyl
group/the number of moles of the hydrosilyl group) of the alkenyl
group to the hydrosilyl group is below 1 and is, for example, 0.10
to 0.99, preferably 0.20 to 0.99, or more preferably 0.50 to 0.99.
In other words, the mixing ratio of the polysiloxane containing
alkenyl groups in its side chain with respect to 100 parts by mass
of the total amount of the cage octasilsesquioxane and the
polysiloxane containing alkenyl groups at both ends is, for
example, 0.001 to 30 parts by mass, or preferably 0.01 to 20 parts
by mass. The mixing ratio of the polysiloxane containing alkenyl
groups in its side chain with respect to 100 parts by mass of the
total amount of the cage octasilsesquioxane and the polysiloxane
containing alkenyl groups at both ends can be also set to be, for
example, 0.01 to 100 parts by mass, or preferably 0.1 to 50 parts
by mass.
[0259] When the above-described molar ratio exceeds the
above-described range, the hydrosilyl group is fewer than the
alkenyl group. In such a case, the excess of the hydrosilyl group
does not sufficiently remain after the reaction and the
thermosetting properties may not be imparted to the sixth silicone
resin composition having both thermoplastic and thermosetting
properties.
[0260] On the other hand, when the above-described molar ratio is
below the above-described range, the hydrosilyl group excessively
remains and the cage octasilsesquioxanes themselves undergo
hydrolysis by moisture in the air and a self-condensation reaction
to be cured, so that flexibility may not be obtained.
[0261] The mixing ratio of the hydrosilylation catalyst (solid
content) with respect to 100 parts by mass of the total amount of
the cage octasilsesquioxane and the polysiloxane containing alkenyl
groups at both ends is, for example, 1.0.times.10.sup.-10 to 3
parts by mass, or preferably 1.0.times.10.sup.-8 to 1 parts by
mass.
[0262] The mixing ratio of the polysiloxane containing alkenyl
groups in its side chain is adjusted so that the number of moles
(X) of the alkenyl group with respect to the number of moles (Y),
which is obtained by subtracting the number of moles of the alkenyl
group in the polysiloxane containing alkenyl groups at both ends
from the number of moles of the hydrosilyl group in the cage
octasilsesquioxane, as the molar ratio (X/Y), is, for example,
0.001 to 1000, or preferably 0.01 to 100.
[0263] In order to prepare the sixth silicone resin composition
having both thermoplastic and thermosetting properties, preferably,
a silicone resin precursor, which is obtained by allowing the cage
octasilsesquioxane to react with the polysiloxane containing
alkenyl groups at both ends in the presence of the hydrosilylation
catalyst, and the polysiloxane containing alkenyl groups in its
side chain are blended.
[0264] That is, first, the cage octasilsesquioxane is allowed to
react with the polysiloxane containing alkenyl groups at both ends
in the presence of the hydrosilylation catalyst in such a mixing
proportion that the number of moles of the hydrosilyl group in the
cage octasilsesquioxane is larger (excessive) than that of the
alkenyl group in the polysiloxane containing alkenyl groups at both
ends. In this way, the silicone resin precursor is obtained.
[0265] To be more specific, in order to obtain the silicone resin
precursor, the above-described cage octasilsesquioxane and the
above-described polysiloxane containing alkenyl groups at both ends
are blended at the above-described mixing proportion, along with
the hydrosilylation catalyst, and the solvent as required, and
thereafter, the mixture is heated as required.
[0266] Examples of the solvent include an aromatic hydrocarbon such
as toluene, an aliphatic hydrocarbon such as hexane, and ester such
as ethyl acetate. Preferably, in view of improving compatibility of
each of the components, an aromatic hydrocarbon is used, or more
preferably, toluene is used.
[0267] The reaction temperature is, for example, 0 to 100.degree.
C., or preferably 20 to 80.degree. C. and the reaction duration is,
for example, 0.5 to 96 hours.
[0268] In this way, the cage octasilsesquioxane is allowed to react
with the polysiloxane containing alkenyl groups at both ends. That
is, the hydrosilyl group in the cage octasilsesquioxane and the
alkenyl group in the polysiloxane containing alkenyl groups at both
ends are allowed to undergo the hydrosilylation reaction.
[0269] The degree of the hydrosilylation reaction of the hydrosilyl
group in the cage octasilsesquioxane with the alkenyl group in the
polysiloxane containing alkenyl groups at both ends can be checked
by .sup.1H-NMR measurement based on the intensity of a signal
derived from the alkenyl group in the polysiloxane containing
alkenyl groups at both ends. The hydrosilylation reaction is
considered to be terminated at the time of disappearance of the
signal.
[0270] In the above-described hydrosilylation reaction, the cage
octasilsesquioxane is allowed to react with the polysiloxane
containing alkenyl groups at both ends so that the number of moles
of the hydrosilyl group is excessive compared with the number of
moles of the alkenyl group. After the reaction, the excess of the
hydrosilyl group remains.
[0271] In this way, the silicone resin precursor is obtained.
[0272] The silicone resin precursor is in a liquid state or in a
semi-solid state.
[0273] Next, the obtained silicone resin precursor and the
polysiloxane containing alkenyl groups in its side chain are
blended at the above-described proportion. By the subsequent
heating (described later), the silicone resin precursor is allowed
to react with the polysiloxane containing alkenyl groups in its
side chain. The solvent is distilled off as required.
[0274] In this way, the sixth silicone resin composition having
both thermoplastic and thermosetting properties can be
obtained.
[0275] The obtained sixth silicone resin composition having both
thermoplastic and thermosetting properties is in a solid state. The
sixth silicone resin composition having both thermoplastic and
thermosetting properties in a solid state is obtained because the
mobility of the polysiloxane containing alkenyl groups at both ends
is reduced due to the steric hindrance of the cage
octasilsesquioxane.
[0276] In the sixth silicone resin composition having both
thermoplastic and thermosetting properties, the molar ratio of the
monovalent hydrocarbon group: hydrogen in R.sup.6 is within a
specific range and therefore, in the cage octasilsesquioxane, the
proportion of the hydrosilyl group to be reacted with the alkenyl
group in the polysiloxane containing alkenyl groups at both ends is
adjusted. Furthermore, the polysiloxane containing alkenyl groups
at both ends is allowed to react with the cage octasilsesquioxane
so that the alkenyl group thereof has the number of moles that is
smaller than the number of moles of the hydrosilyl group in the
cage octasilsesquioxane. Therefore, the obtained sixth silicone
resin composition having both thermoplastic and thermosetting
properties can have both the thermoplastic properties and the
thermosetting properties, while having an excellent transparency
and heat resistance.
[0277] That is, the sixth silicone resin composition having both
thermoplastic and thermosetting properties is once plasticized (or
liquefied) by the above-described heating and then, is thermally
cured.
[0278] The thermoplastic temperature of the silicone resin
composition having both thermoplastic and thermosetting properties
is, for example, 40 to 150.degree. C., or preferably 50 to
100.degree. C. The thermoplastic temperature is the temperature at
which the silicone resin composition having both thermoplastic and
thermosetting properties shows the thermoplastic properties. To be
specific, the thermoplastic temperature is the temperature at which
the silicone resin composition having both thermoplastic and
thermosetting properties in a solid state is softened by heating to
be brought into a completely liquid state and is substantially the
same as the softening temperature.
[0279] The thermosetting temperature of the silicone resin
composition having both thermoplastic and thermosetting properties
is, for example, 150 to 300.degree. C., or preferably 180 to
250.degree. C. or is, for example, 100 to 250.degree. C., or
preferably 120 to 250.degree. C.
[0280] The first silicone resin composition having both
thermoplastic and thermosetting properties is described in Japanese
Unexamined Patent Publication No. 2011-148883 or the like and
contains, for example, a silicone resin containing aminopropyl
groups at both ends, an organohydrogensiloxane, tolylene
2,4-diisocyanate, and a platinum divinyl siloxane complex. The
second silicone resin composition having both thermoplastic and
thermosetting properties is described in Japanese Unexamined Patent
Publication No. 2011-202099 or the like and contains, for example,
a silicone resin containing amino groups at both ends, tolylene
2,4-diisocyanate, and di-t-butyl peroxide. The third silicone resin
composition having both thermoplastic and thermosetting properties
contains, for example, a cage octasilsesquioxane having a
hydrosilyl group, an alkenyl group-containing polysiloxane, and a
platinum divinyl siloxane complex. The fourth silicone resin
composition having both thermoplastic and thermosetting properties
contains, for example, a cage octasilsesquioxane having a
hydrosilyl group, an alkenyl group-containing polysiloxane, a
platinum divinyl siloxane complex, and a hydroxyl group-containing
polysiloxane. The fifth silicone resin composition having both
thermoplastic and thermosetting properties contains, for example, a
cage octasilsesquioxane having a hydrosilyl group, an alkenyl
group-containing polysiloxane, a platinum divinyl siloxane complex,
and a side-chain type organohydrogenpolysiloxane. The sixth
silicone resin composition having both thermoplastic and
thermosetting properties contains, for example, a cage
octasilsesquioxane having a hydrosilyl group, a polysiloxane
containing alkenyl groups at both ends, a platinum divinyl siloxane
complex, and a straight chain siloxane-containing polysiloxane.
[0281] The mixing ratio of the second silicone resin composition
with respect to the phosphor encapsulating composition is, for
example, 30 to 99.9 mass %, or preferably 40 to 90 mass %.
[0282] In order to prepare the phosphor encapsulating composition,
the phosphor and the second silicone resin composition are blended.
An additive illustrated in the transparent composition can be added
to the phosphor encapsulating composition at an appropriate
proportion.
[0283] When the second silicone resin composition is the two-step
curable type silicone resin composition, preferably, the phosphor
is added to the uncured material of the two-step curable type
silicone resin composition to be uniformly mixed.
[0284] Also, when the second silicone resin composition is the
silicone resin composition having both thermoplastic and
thermosetting properties, preferably, the phosphor is added to the
thermoplastic material of the silicone resin composition having
both thermoplastic and thermosetting properties to be uniformly
mixed.
[0285] In order to fabricate the encapsulating sheet 1 shown in
FIG. 1, as shown in FIG. 2, first, the transparent layer 2 in which
the concave portions 4 are formed is fabricated.
[0286] The transparent layer 2 is formed from the above-described
transparent composition into the above-described shape by, for
example, a thermal molding method (ref: FIGS. 3 and 4), a
laminating method (ref: FIG. 5), or the like.
[0287] Examples of the thermal molding method include a method (a
compression molding method) in which as shown in FIG. 3 (a), a
liquid transparent composition is charged into a compression
molding machine 6 including a mold die 5 corresponding to the
concave portions 4 and subsequently, as shown in FIG. 3 (b),
closing of the mold die 5 is performed with heating and a method (a
thermal pressing method) in which a liquid transparent composition
is applied onto a substrate (not shown) to form a transparent sheet
7, thereafter, as shown in FIG. 4 (a), the transparent sheet 7 is
set into a thermal pressing machine 8 including the mold die 5
corresponding to the concave portions 4, and as shown in FIG. 4
(b), thermal pressing is conducted.
[0288] Examples of the substrate include a polyester film such as a
polyethylene terephthalate (PET) film; a polycarbonate film; a
polyolefin film such as a polyethylene film and a polypropylene
film; a polystyrene film; an acrylic film; and a resin film such as
a silicone resin film and a fluorine resin film. In addition, an
example of the substrate also includes a metal foil such as a
copper foil and a stainless steel foil.
[0289] Of the substrates, preferably, a resin film is used, or more
preferably, a polyester film is used.
[0290] A release treatment is performed on the surface of the
substrate as required.
[0291] The thickness of the substrate is, for example, in view of
handling ability and cost, 10 to 200 .mu.m, or preferably 20 to 100
.mu.m.
[0292] In the laminating method, as shown in FIG. 5 (a), a liquid
transparent composition is applied onto a substrate to form a
plurality (for example, two pieces) of the transparent sheets 7.
Thereafter, as shown in FIG. 5 (b), in one transparent sheet 7A,
through holes 9 which correspond to the concave portions 4 and pass
through the one transparent sheet 7A in the thickness direction are
formed. Then, as shown in FIG. 5 (c), the one transparent sheet 7A
and the other transparent sheet 7B are attached to each other.
[0293] In order to form the transparent layer 2 into the
above-described shape, to be specific, when the transparent layer 2
is formed from a transparent composition containing a thermosetting
silicone resin composition before final curing, to be more
specific, when the transparent layer 2 is formed as a first-step
cured material of a two-step curable type silicone resin
composition, for example, a compression molding method, a thermal
pressing method, or a laminating method is used. Preferably, a
laminating method is used.
[0294] In order to form the transparent layer 2 as the first-step
cured material of the two-step curable type silicone resin
composition by the compression molding method, first, as shown in
FIG. 3 (a), a liquid transparent composition containing an uncured
material of a two-step curable type silicone resin composition is
charged into the compression molding machine 6 and subsequently, as
shown in FIG. 3 (b), closing of the mold die 5 is performed with
heating, so that the two-step curable type silicone resin
composition is brought into a first-step cured material and the
transparent layer 2 which is prepared from the transparent
composition containing the first-step cured material is
fabricated.
[0295] In the compression molding machine, the pressure is, for
example, 0.1 to 30 MPa, or preferably 1 to 10 MPa; the temperature
is, for example, 80 to 200.degree. C., or preferably 100 to
150.degree. C.; and the duration is, for example, 1 to 300 minutes,
or preferably 5 to 30 minutes.
[0296] In order to form the transparent layer 2 as the first-step
cured material of the two-step curable type silicone resin
composition by the thermal pressing method, a liquid transparent
composition containing an uncured material of a two-step curable
type silicone resin composition is applied onto a substrate (not
shown) to be then heated, so that the two-step curable type
silicone resin composition is brought into a first-step cured
material. In this way, the transparent sheet 7 (a B-stage sheet,
ref: FIG. 4 (a)) which is prepared from the transparent composition
containing the first-step cured material is formed. Thereafter, as
shown in FIG. 4 (a), the transparent sheet 7 is set into the
thermal pressing machine 8 and then, as shown in FIG. 4 (b),
thermal pressing is conducted, so that the transparent layer 2 is
fabricated.
[0297] In order to apply the liquid transparent composition to the
substrate, an application method such as a doctor blade method, a
gravure coater method, or a fountain coater method is used.
[0298] The heating temperature of the transparent composition after
application is, for example, 40 to 150.degree. C., or preferably 80
to 150.degree. C. The heating duration thereof is, for example, 1
minute to 24 hours, or preferably 1 minute to 1 hour.
[0299] The pressure in the thermal pressing machine 8 is, for
example, 0.1 to 30 MPa, or preferably 1 to 10 MPa; the temperature
is, for example, 80 to 200.degree. C., or preferably 100 to
150.degree. C.; and the pressing duration is, for example, 0.5 to
60 minutes, or preferably 1 to 30 minutes.
[0300] In order to form the transparent layer 2 as the first-step
cured material of the two-step curable type silicone resin
composition by the laminating method, a transparent composition
containing an uncured material of a two-step curable type silicone
resin composition is applied onto a substrate to be then heated, so
that as shown in FIG. 5 (a), the two-step curable type silicone
resin composition is brought into a first-step cured material and
two pieces of the transparent sheets 7 which are prepared from the
transparent composition containing the first-step cured material
are formed. The fabrication conditions of the transparent sheets
are the same as those of the thermal pressing method. Thereafter,
as shown in FIG. 5 (b), in the one transparent sheet 7A, the
through holes 9 are formed. Then, as shown in FIG. 5 (c), the one
transparent sheet 7A and the other transparent sheet 7B are
attached to each other using, for example, a laminator or the
like.
[0301] In addition, when the transparent layer 2 is formed from a
thermosetting silicone resin composition after final curing, to be
more specific, when the transparent layer 2 is formed as a cured
material of a one-step curable type silicone resin composition, for
example, a compression molding method is used.
[0302] In order to form the transparent layer 2 as the cured
material of the one-step curable type silicone resin composition by
the compression molding method, first, a main agent and a
cross-linking agent are mixed and the liquid mixture is prepared as
a liquid transparent composition containing an uncured material of
the one-step curable type silicone resin composition. Next, as
shown in FIG. 3 (a), the transparent composition is charged into
the compression molding machine 6 and subsequently, as shown in
FIG. 3 (b), closing of the mold die 5 is performed with heating, so
that the one-step curable type silicone resin composition is
brought into a cured material and the transparent layer 2 which is
prepared from the transparent composition containing the cured
material is fabricated. Thereafter, the obtained transparent layer
2 is subjected to post curing as required.
[0303] In the compression molding machine, the pressure is, for
example, 0.1 to 30 MPa, or preferably 1 to 10 MPa; the temperature
is, for example, 80 to 200.degree. C., or preferably 100 to
150.degree. C.; and the duration is, for example, 1 to 300 minutes,
or preferably 5 to 30 minutes.
[0304] The post curing performed in the compression molding method
as required is a treatment so as to complete the curing of an
uncured portion which remains in a small portion after
substantially bringing the one-step curable type silicone resin
composition into the cured material. The temperature thereof is,
for example, 100 to 200.degree. C., or preferably 100 to
180.degree. C. and the duration thereof is, for example, 10 to 300
minutes, or preferably 30 to 180 minutes.
[0305] On the other hand, when the transparent layer 2 is formed
from a transparent composition containing a thermosetting silicone
resin composition after final curing, to be more specific, when the
transparent layer 2 is formed as a second-step cured material of a
two-step curable type silicone resin composition, for example, a
compression molding method, a thermal pressing method, or a
laminating method is used.
[0306] In order to form the transparent layer 2 as the second-step
cured material of the two-step curable type silicone resin
composition by the compression molding method, first, as shown in
FIG. 3 (a), a liquid transparent composition containing an uncured
material of a two-step curable type silicone resin composition is
charged into the compression molding machine 6 and subsequently, as
shown in FIG. 3 (b), closing of the mold die 5 is performed with
heating, so that the two-step curable type silicone resin
composition is brought into a second-step cured material at one
time (by one step) and in this way, the transparent layer 2 which
is prepared from the transparent composition containing the
second-step cured material is fabricated. The conditions of the
compression molding machine are as follows: the pressure of, for
example, 0.1 to 30 MPa, or preferably 1 to 10 MPa; the temperature
of, for example, 80 to 200.degree. C., or preferably 100 to
150.degree. C.; and the duration of, for example, 1 to 300 minutes,
or preferably 10 to 60 minutes.
[0307] In order to form the transparent layer 2 as the second-step
cured material of the two-step curable type silicone resin
composition by the thermal pressing method, a liquid transparent
composition containing an uncured material of the two-step curable
type silicone resin composition is applied onto a substrate (not
shown) to be then heated, so that the two-step curable type
silicone resin composition is brought into a first-step cured
material and the transparent sheet 7 (a B-stage sheet, ref: FIG. 4
(a)) which is prepared from the transparent composition containing
the first-step cured material is formed. Thereafter, as shown in
FIG. 4 (a), the transparent sheet 7 in a B-stage state is set into
the thermal pressing machine 8 and then, as shown in FIG. 4 (b),
thermal pressing is conducted, so that the two-step curable type
silicone resin composition is brought into the second-step cured
material and the transparent layer 2 which is prepared from the
transparent composition containing the second-step cured material
is fabricated.
[0308] The heating conditions of the transparent composition after
application are the same as described above. The pressure in the
thermal pressing machine 8 is, for example, 0.1 to 30 MPa, or
preferably 1 to 10 MPa; the temperature is, for example, 80 to
200.degree. C., or preferably 100 to 150.degree. C.; and the
pressing duration is, for example, 0.5 to 60 minutes, or preferably
1 to 30 minutes.
[0309] In order to form the transparent layer 2 as the second-step
cured material of the two-step curable type silicone resin
composition by the laminating method, a liquid transparent
composition containing an uncured material of a two-step curable
type silicone resin composition is applied onto a substrate to be
then heated, so that as shown in FIG. 5 (a), the two-step curable
type silicone resin composition is brought into a first-step cured
material and two pieces of the transparent sheets 7 (B-stage
sheets) which are prepared from the transparent composition
containing the first-step cured material are formed. The
fabrication conditions of the transparent sheets are the same as
those of the thermal pressing method. Thereafter, as shown in FIG.
5 (b), in the one transparent sheet 7A, the through holes 9 are
formed. Then, as shown in FIG. 5 (c), the one transparent sheet 7A
and the other transparent sheet 7B are attached to each other by a
thermal compression bonding. In this way, the two-step curable type
silicone resin composition is brought into the second-step cured
material and the transparent layer 2 which is prepared from the
transparent composition containing the second-step cured material
is fabricated.
[0310] The conditions of the thermal compression bonding are as
follows: the pressure of, for example, 0.1 to 30 MPa, or preferably
1 to 10 MPa; the temperature of, for example, 80 to 200.degree. C.,
or preferably 100 to 150.degree. C.; and the duration of, for
example, 0.5 to 60 minutes, or preferably 1 to 30 minutes.
[0311] When the transparent layer 2 is formed as the second-step
cured material of the two-step curable type silicone resin
composition, the first-step cured material of the two-step curable
type silicone resin composition which is formed by the
above-described compression molding method, thermal pressing
method, laminating method, or the like can be subjected to the post
curing. The conditions of the post curing is as follows: the
temperature of, for example, 100 to 200.degree. C., or preferably
100 to 180.degree. C. and the duration of, for example, 10 to 300
minutes, or preferably 30 to 180 minutes.
[0312] In the formation of the transparent layer 2, preferably, the
transparent layer 2 is formed as a first-step cured material of a
two-step curable type silicone resin composition.
[0313] In this way, the transparent layer 2 in which the concave
portions 4 are formed is fabricated.
[0314] Thereafter, in this method, as shown in FIG. 1, the phosphor
encapsulating layers 3 fill the concave portions 4 in the
transparent layer 2.
[0315] To be specific, the above-described phosphor encapsulating
composition is poured into the concave portions 4 in the
transparent layer 2 using a potting device.
[0316] To be specific, when the phosphor encapsulating composition
contains an uncured material (before curing in the first step) of
the two-step curable type silicone resin composition, the liquid
phosphor encapsulating composition is poured into the concave
portions 4 in the transparent layer 2.
[0317] On the other hand, when the phosphor encapsulating
composition contains a silicone resin composition having both
thermoplastic and thermosetting properties, the silicone resin
composition having both thermoplastic and thermosetting properties
is heated to be brought into a thermoplastic material and the
phosphor encapsulating composition containing the thermoplastic
material is poured into the concave portions 4 in the transparent
layer 2. The heating temperature is, for example, 50 to 150.degree.
C., or preferably 80 to 120.degree. C.
[0318] Thereafter, when the second silicone resin composition in
the phosphor encapsulating composition is an uncured material
(before curing in the first step) of the two-step curable type
silicone resin composition, the two-step curable type silicone
resin composition is brought into a first-step cured material by
heating at, for example, 40 to 150.degree. C. for 1 to 24
hours.
[0319] On the other hand, when the second silicone resin
composition in the phosphor encapsulating composition is a
thermoplastic material of the silicone resin composition having
both thermoplastic and thermosetting properties, the silicone resin
composition having both thermoplastic and thermosetting properties
is solidified by allowing to stand at normal temperature for 0.1 to
24 hours.
[0320] In this way, the phosphor encapsulating layers 3 prepared
from the phosphor encapsulating composition fill the concave
portions 4.
[0321] In this way, the encapsulating sheet 1 including the
transparent layer 2 and the phosphor encapsulating layers 3 is
obtained.
[0322] FIG. 6 shows views for illustrating a method for producing
one embodiment of the encapsulating sheet of the present invention:
(a) illustrating a step of disposing the encapsulating sheet on a
board and (b) illustrating a step of compressively bonding the
encapsulating sheet with respect to the board. FIG. 7 shows a plan
view of the board shown in FIG. 6 (a).
[0323] Next, a method for producing a light emitting diode device
10 using the encapsulating sheet 1 is described with reference to
FIGS. 6 and 7.
[0324] First, in this method, as shown in FIGS. 6 (a) and 7, the
board 12 on which the light emitting diode elements 11 are mounted
is prepared.
[0325] The board 12 is formed into a generally flat plate shape. To
be specific, the board 12 is formed of a laminated board in which a
conductive layer provided with electrode pads 13 and a wire (not
shown) is laminated, as a circuit pattern, on an insulating board.
The insulating board is formed of, for example, a silicon board, a
ceramic board, a polyimide resin board, or the like. Preferably,
the insulating board is formed of a ceramic board, to be specific,
a sapphire (AL.sub.2O.sub.3) board.
[0326] The electrode pads 13 are provided at spaced intervals to
the region on which the light emitting diode elements 11 are
mounted. To be specific, the electrode pads 13 are disposed at the
end portions of the board 12. The conductive layer is formed of,
for example, a conductor such as gold, copper, silver, or nickel.
The thickness of the board 12 is, for example, 30 to 1500 .mu.m, or
preferably 500 to 1000 .mu.m.
[0327] A plurality of the light emitting diode elements 11 are
disposed in alignment at spaced intervals to each other in the
plane direction on the upper surface of the board 12. Each of the
light emitting diode elements 11 is formed into a generally
rectangular shape in plane view and into a generally rectangular
shape in sectional view. Each of the light emitting diode elements
11 is flip-chip-mounting connected or wire-bonding connected to the
conductive layer in the board 12 and in this way, is electrically
connected to the electrode pads 13. Each of the light emitting
diode elements 11 is an element which emits blue light.
[0328] The thickness of each of the light emitting diode elements
11 is, for example, 50 to 300 .mu.m, or preferably 100 to 200
.mu.m. The length of one side thereof is, for example, 0.5 to 2 mm,
or preferably 0.1 to 1.5 mm and the gap therebetween is, for
example, 0.05 to 5.0 mm, or preferably 0.5 to 3.5 mm. The pitch of
each of the light emitting diode elements 11 (that is, the total of
the above-described gap and the above-described length of one side)
is, for example, 1 to 5 mm.
[0329] Next, the encapsulating sheet 1 shown in FIG. 1 is prepared
and as shown in FIG. 6 (a), the encapsulating sheet 1 which is
reversed upside down is disposed at the upper side of the board 12
so that each of the phosphor encapsulating layers 3 and each of the
light emitting diode elements 11 are opposed to each other in the
thickness direction. Thereafter, as shown by arrows in FIG. 6 (a),
and FIG. 6 (b), the encapsulating sheet 1 is compressively bonded
to the board 12 so that each of the phosphor encapsulating layers 3
embeds each of the light emitting diode elements 11.
[0330] The temperature of the compression bonding is, for example,
70 to 250.degree. C., or preferably 100 to 200.degree. C.; the
pressure is, for example, 0.1 to 10 MPa, or preferably 0.5 to 5
MPa; and the duration is, for example, 1 to 60 minutes, or
preferably 5 to 30 minutes.
[0331] Thereafter, when the transparent composition in the
transparent layer 2 and/or the phosphor encapsulating composition
in the phosphor encapsulating layer 3 contain/contains a
thermosetting silicone resin composition before final curing, the
transparent layer 2 and/or the phosphor encapsulating layer 3
are/is heated, so that the transparent composition and/or the
phosphor encapsulating composition are/is cured (subjected to the
post curing).
[0332] The temperature of the post curing is, for example, 80 to
200.degree. C., or preferably 100 to 180.degree. C. and the heating
duration is, for example, 10 to 300 minutes, or preferably 30 to
180 minutes.
[0333] In this way, the light emitting diode elements 11 are
encapsulated by the phosphor encapsulating layers 3.
[0334] In the encapsulating sheet 1, the method for producing the
light emitting diode device 10 using the encapsulating sheet 1, and
the light emitting diode device 10 produced by the method, the
transparent layer 2 is formed from the transparent composition
containing the first silicone resin composition, so that a crack
and coloring (to be specific, yellowing or the like) in the
transparent layer 2 can be suppressed.
[0335] The transparent layer 2 is formed from the transparent
composition containing the first silicone resin composition and the
phosphor encapsulating layers 3 are formed from the phosphor
encapsulating composition containing the second silicone resin
composition, so that the affinity between the transparent layer 2
and the phosphor encapsulating layers 3 is high and therefore, a
peeling therebetween can be suppressed.
[0336] The phosphor encapsulating layers 3 are, in the concave
portions 4 formed in the transparent layer 2, formed from the
phosphor encapsulating composition containing the phosphor. The
light emitting diode elements 11 are embedded by the phosphor
encapsulating layers 3, so that the mixing amount of the phosphor
in the phosphor encapsulating layers 3 in which the light emitting
diode elements 11 are embedded is sufficiently ensured and light
emitted from the light emitting diode elements 11 can be surely
converted, while the mixing amount of the phosphor in the
encapsulating sheet 1 can be reduced, compared with that in a case
where the phosphor encapsulating layer 3 is formed on the entire
surface of the transparent layer 2.
[0337] Therefore, the production cost of the encapsulating sheet 1
can be reduced.
[0338] As a result, in the method for producing the light emitting
diode device 10 using the encapsulating sheet 1, the production
cost of the light emitting diode device 10 can be reduced.
[0339] In the embodiment in FIG. 2 (a), the concave portion 4 is
formed into a generally circular shape in plane view.
Alternatively, for example, though not shown, the concave portion 4
can be formed into a generally rectangular shape in plane view. In
such a case, the length of one side of the concave portion 4 is,
for example, 1 to 10 mm, or preferably 1 to 5 mm.
[0340] In the embodiments in FIGS. 1 and 6 (b), a plurality of the
concave portions 4 are formed in the encapsulating sheet 1 and the
phosphor encapsulating layers 3 fill the concave portions 4, so
that a plurality of the light emitting diode elements 11 are
encapsulated by the phosphor encapsulating layers 3. Alternatively,
for example, though not shown, one piece of the concave portion 4
is formed and the phosphor encapsulating layer 3 fills the concave
portion 4, so that one piece of the light emitting diode element 11
can be encapsulated by the phosphor encapsulating layer 3.
[0341] Also, though not shown in FIG. 1, for example, a light
scattering layer, a protecting layer (a high-hardness layer or the
like), or the like can be laminated on the lower surface of the
transparent layer 2.
EXAMPLES
[0342] While the present invention will be described hereinafter in
further detail with reference to Production Examples, Comparative
Production Examples, Examples, and Comparative Examples, the
present invention is not limited to these Production Examples,
Comparative Production Examples, Examples, and Comparative
Examples.
Fabrication of Transparent Layer
Production Example 1
Transparent Layer: Silicone Resin Composition in C-Stage State
[0343] A liquid and B liquid in an addition reaction curable type
silicone resin composition (trade name: LR-7665, manufactured by
WACKER ASAHIKASEI SILICONE CO., LTD.) were mixed at a mixing ratio
of 1/1 to prepare a liquid mixture.
[0344] Next, the liquid mixture was charged into a compression
molding machine (ref: FIG. 3 (a)) and mold closing thereof was
performed at a pressure of 1.6 MPa, a temperature of 130.degree.
C., for 5 minutes, so that a transparent layer was formed (ref:
FIG. 3 (b)) to be then subjected to a post curing at 150.degree. C.
for 2 hours (ref: FIG. 3).
[0345] The thickness of the transparent layer was 1 mm and in the
transparent layer, nine pieces of concave portions that were dented
from the surface inwardly were formed. Each of the concave portions
was formed into a circular shape having an inner diameter of 2 mm
and a depth of 0.5 mm. The gap between the concave portions was 1
mm (ref: FIG. 2).
[0346] The addition reaction curable type silicone resin
composition in the transparent layer was in a C-stage state.
Production Example 2
Transparent Layer: Silicone Resin Composition in B-Stage State
[0347] 15.71 g (0.106 mol) of a vinyltrimethoxysilane (an ethylenic
silicon compound) and 2.80 g (0.0118 mol) of a
(3-glycidoxypropyl)trimethoxysilane (an epoxy group-containing
silicon compound) were blended with respect to 2031 g (0.177 mol)
of a polydimethylsiloxane containing silanol groups at both ends (a
polysiloxane containing silanol groups at both ends, in general
formula (1), all of the R.sup.1s are methyl, an average of "n" is
155, a number average molecular weight of 11500, a silanol group
equivalent of 0.174 mmol/g) to be stirred and mixed.
[0348] The molar ratio (the number of moles in SiOH group/the total
number of moles in SiOCH.sub.3 group) of the SiOH group in the
polydimethylsiloxane containing silanol groups at both ends to the
SiOCH.sub.3 group in the vinyltrimethoxysilane and the
(3-glycidoxypropyl)trimethoxysilane was 1/1.
[0349] After the stirring and mixing, 0.97 mL (0.766 g, the content
of the catalyst: 0.88 mmol, corresponding to 0.50 mol with respect
to 100 mol of the polydimethylsiloxane containing silanole groups
at both ends) of a methanol solution of the tetramethylammonium
hydroxide (a condensation catalyst, a concentration of 10 mass %)
was added thereto to be stirred at 40.degree. C. for 1 hour.
Thereafter, the obtained mixture was stirred under a reduced
pressure (10 mmHg) at 40.degree. C. for 1 hour and volatile
components (methanol or the like) were removed.
[0350] Thereafter, the pressure of the system was brought back to
the normal pressure and then, 44.5 g (0.022 mol) of an
organohydrogensiloxane (manufactured by Shin-Etsu Chemical Co.,
Ltd., a dimethylpolysiloxane-co-methylhydrogenpolysiloxane, a
number average molecular weight of 2000, a hydrosilyl group
equivalent of 7.14 mmol/g) was added to the reacting product to be
stirred at 40.degree. C. for 1 hour.
[0351] The molar ratio (CH.sub.2.dbd.CH--/SiH) of the vinyl group
(CH.sub.2.dbd.CH--) in the vinyltrimethoxysilane to the hydrosilyl
group (the SiH group) in the organohydrogensiloxane was 1/3.
[0352] Thereafter, 0.13 g (0.13 mL, the content of the platinum of
2 mass %, as a platinum corresponding to 5.8.times.10.sup.-3 parts
by mass with respect to 100 parts by mass of the
organohydrogensiloxane) of a siloxane solution of a platinum
carbonyl complex (an addition catalyst, a platinum concentration of
2 mass %) was added to the system to be stirred at 40.degree. C.
for 10 minutes, so that a thermosetting silicone resin composition
(a condensation reaction and addition reaction curable type
silicone resin composition) in a liquid state at normal temperature
was obtained.
[0353] Next, the thermosetting silicone resin composition was
applied onto a PET film having a thickness of 50 .mu.m so as to
have a thickness of 0.5 mm. Then, the obtained film was heated at
135.degree. C. for 10 minutes, so that a transparent sheet prepared
from a thermosetting silicone resin composition in a B-stage state
was formed.
[0354] Thereafter, two pieces of sheets each having a size of 10
mm.times.10 mm were cut out from the transparent sheet (ref: FIG. 5
(a)) and nine pieces of through holes were formed in one piece of
sheet (ref: FIG. 5 (b)). Each of the through holes was formed into
a circular shape having an inner diameter of 2 mm. The gap between
the through holes was 1 mm.
[0355] Next, one piece of sheet in which the through holes were
formed and the other piece of sheet were attached to each other by
a laminator, so that a transparent layer in which concave portions
corresponding to the through holes were formed was fabricated (ref:
FIG. 5 (c)).
Comparative Production Example 1
Transparent Layer: Epoxy Resin Composition
[0356] 45 parts by mass of a bisphenol A epoxy resin (Epicoat
EP1256, an epoxy equivalent of 7500, manufactured by Japan Epoxy
Resins Co., Ltd.), 33 parts by mass of an alicyclic epoxy resin
(EHPE3150, an epoxy equivalent of 260, manufactured by Daicel
Corporation), 22 parts by mass of 4-methylhexahydrophthalic
anhydride (MH-700, manufactured by New Japan Chemical Co., Ltd.),
and 1.2 parts by mass of 2-methylimidazole (manufactured by SHIKOKU
CHEMICALS CORPORATION) were dissolved in methyl ethyl ketone so as
to have a solid concentration of 50 mass %, so that an epoxy resin
composition solution was prepared.
[0357] Next, the epoxy resin composition solution was applied onto
a PET film (a size of 30 cm.times.10 cm) having a thickness of 50
.mu.m so as to have a thickness of 0.1 mm. Then, the obtained film
was heated at 130.degree. C. for 2 minutes to be dried, so that a
base sheet in a C-stage state was formed.
[0358] Thereafter, the same operation was repeated nine times, so
that a total of 10 pieces of base sheets (each having a size of 30
cm.times.10 cm) were prepared.
[0359] Thereafter, 10 pieces of the base sheets were thermally
laminated at 100.degree. C., so that a transparent sheet having a
thickness of 1.0 mm was fabricated.
[0360] Thereafter, a piece of sheet having a size of 10 mm.times.10
mm was cut out from the transparent sheet and nine pieces of the
concave portions were formed in the piece of sheet, so that a
transparent layer was fabricated. The size of the concave portion
was the same as that of the concave portion in Production Example
1.
Production of Encapsulating Sheet
Example 1
Transparent Layer: Silicone Resin Composition in C-Stage
State/Phosphor Encapsulating Layer: Phosphor+Thermoplastic Material
of Silicone Resin Composition
[0361] 35.8 mL (160.6 mol) of a tetraethoxysilane was gradually
added dropwise to a liquid mixture of 66.8 mL (158.6 mol) of
tetramethyl ammonium hydroxide (a 25% methanol solution), 32.8 mL
of methanol, and 24.6 mL of a distilled water. The obtained mixture
was stirred for a whole day to be allowed to react.
[0362] Then, the reaction liquid was filtrated and the filtrate was
added dropwise to a liquid mixture of 428 mL of hexane, 7.1 g (75
mmol) of a dimethylchlorosilane, and 24.4 g (225 mmol) of a
trimethylchlorosilane. The obtained mixture was stirred for a whole
day. Thereafter, the reacting product was extracted with hexane and
magnesium sulfate was added to the extract to be dried. Thereafter,
the hexane was once removed and then, the hexane was further added
to the obtained mixture so as to cause recrystallization, so that a
white and solid cage octasilsesquioxane was obtained.
[0363] It was confirmed by a .sup.1H-NMR that the obtained cage
octasilsesquioxane had a structure in formula (6), and R.sup.5 was
a methyl group and R.sup.6 was hydrogen or a methyl group in
formula (6). The molar ratio (an average value in the cage
octasilsesquioxane as a whole) of the methyl group to the hydrogen
in R.sup.6 was calculated and determined to be methyl group:
hydrogen=6:2.
[0364] 0.36 g of the obtained cage octasilsesquioxane, 0.24 g of a
polysiloxane containing alkenyl groups at both ends (in formula
(7), R.sup.7 is a methyl group, R.sup.8 is a vinyl group, "a" is 8;
a number average molecular weight of 800), 1 g of toluene, and 0.1
.mu.L of a platinum-divinylsiloxane complex solution (a
hydrosilylation catalyst, a toluene solution, a platinum
concentration of 2 mass %) were blended and the obtained mixture
was stirred at 50.degree. C. for 15 hours. In this way, a silicone
resin precursor was obtained. The molar ratio (=vinyl
group/hydrosilyl group) of the vinyl group in the polysiloxane
containing alkenyl groups at both ends to the hydrosilyl group in
the cage octasilsesquioxane was 0.91.
[0365] Thereafter, 0.03 g (5.0 parts by mass with respect to 100
parts by mass of the total amount of the cage octasilsesquioxane
and the polysiloxane containing alkenyl groups at both ends) of a
straight chain siloxane-containing polysiloxane (in formula (8),
R.sup.9 is a methyl group, R.sup.10 is a vinyl group, "b"=120,
"c"=10; a number average molecular weight of 10000, the content of
the vinyl group of 0.98 mmol/g) was blended in the obtained
silicone resin precursor to be mixed.
[0366] The ratio (X/Y) of the vinyl group in the straight chain
siloxane-containing polysiloxane to the residual hydrosilyl group
in the silicone resin precursor was, in molar ratio, 0.49.
[0367] Thereafter, the toluene was distilled off, so that a white
turbid and solid silicone resin composition (a silicone resin
composition having both thermoplastic and thermosetting properties)
was obtained.
[0368] The content ratio of the straight chain siloxane containing
polysiloxane in the silicone resin composition was 4.8 mass %.
[0369] Thereafter, 87 g of the silicone resin composition was
heated at 80.degree. C. to be melted so as to be brought into a
thermoplastic material. 13 g of a phosphor
(Y.sub.3Al.sub.5O.sub.12:Ce (YAG:Ce), a sphere shape, an average
particle size of 17 .mu.m) was added thereto to be uniformly
stirred, so that a phosphor encapsulating composition containing
the phosphor and the thermoplastic material of the silicone resin
composition was prepared.
[0370] Thereafter, 1.7 mg of the phosphor encapsulating composition
was poured into each of the concave portions in the transparent
layer in Production Example 1 using a potting device to be then
allowed to stand at normal temperature for 24 hours and the
phosphor encapsulating composition was solidified, so that a
phosphor encapsulating layer was formed. In this way, an
encapsulating sheet including the transparent layer and the
phosphor encapsulating layers which filled the concave portions was
obtained.
Example 2
Transparent Layer: Silicone Resin Composition in B-Stage
State/Phosphor Encapsulating Layer: Phosphor+Thermoplastic Material
of Silicone Resin Composition
[0371] A phosphor encapsulating composition was poured and
subsequently, a phosphor encapsulating layer was formed, so that an
encapsulating sheet was obtained in the same manner as in Example
1, except that the transparent layer (the transparent layer
prepared from the silicone resin composition in a B-stage state) in
Production Example 2 was used instead of the transparent layer (the
transparent layer prepared from the silicone resin composition in a
C-stage state) in Production Example 1.
Example 3
Transparent Layer: Silicone Resin Composition in C-Stage
State/Phosphor Encapsulating Layer: Phosphor+Silicone Resin
Composition in B-Stage State
[0372] A thermosetting silicone resin composition (a condensation
reaction and addition reaction curable type silicone resin
composition) in an A-stage state and a liquid state at normal
temperature, which was the same as that in Production Example 2,
was prepared.
[0373] Thereafter, 13 g of a phosphor (Y.sub.3Al.sub.5O.sub.12:Ce
(YAG:Ce), a sphere shape, an average particle size of 17 .mu.m) was
added to 87 g of the thermosetting silicone resin composition to be
uniformly stirred, so that a phosphor encapsulating composition
containing a phosphor and a thermosetting silicone resin
composition (an uncured material) was prepared.
[0374] Thereafter, 1.7 mg of the phosphor encapsulating composition
was poured into each of the concave portions in the transparent
layer in Production Example 1 using a potting device to be then
heated at 135.degree. C. for 10 minutes and the thermosetting
silicone resin composition of the phosphor encapsulating
composition was brought into a B-stage state, so that a phosphor
encapsulating layer was formed. In this way, an encapsulating sheet
including the transparent layer and the phosphor encapsulating
layers which filled the concave portions was obtained.
Comparative Example 1
Transparent Layer: Epoxy Resin Composition in C-Stage
State/Phosphor Encapsulating Layer: Phosphor+Thermoplastic Material
of Silicone Resin Composition
[0375] A phosphor encapsulating composition was poured and
subsequently, a phosphor encapsulating layer was formed, so that an
encapsulating sheet was obtained in the same manner as in Example
1, except that the transparent layer (the transparent layer
prepared from the epoxy resin composition in a C-stage state) in
Comparative Production Example 1 was used instead of the
transparent layer (the transparent layer prepared from the silicone
resin composition in a C-stage state) in Production Example 1.
Comparative Example 2
Single Layered Sheet of Phosphor Encapsulating Layer:
Phosphor+Thermoplastic Material of Silicone Resin Composition
[0376] A thermosetting silicone resin composition (a condensation
reaction and addition reaction curable type silicone resin
composition) in a liquid state at normal temperature, which was the
same as that in Production Example 2, was prepared.
[0377] Thereafter, 7.7 g of a phosphor (Y.sub.3Al.sub.5O.sub.12:Ce
(YAG:Ce), a sphere shape, an average particle size of 17 .mu.m) was
added to 92.3 g of the thermosetting silicone resin composition to
be uniformly stirred, so that a phosphor encapsulating composition
containing the phosphor and the thermosetting silicone resin
composition (an uncured material) in an A-stage state was
prepared.
[0378] Thereafter, the phosphor encapsulating composition was
applied onto a PET film having a thickness of 50 .mu.m so as to
have a thickness of 1.0 mm. Then, the obtained film was heated at
135.degree. C. for 10 minutes, so that a single layered sheet of a
phosphor encapsulating layer formed from the phosphor encapsulating
composition containing the phosphor and the thermosetting silicone
resin composition in a B-stage state was formed.
[0379] The obtained single layered sheet of a phosphor
encapsulating layer served as an encapsulating sheet.
[0380] <Production of Light Emitting Diode Device>
[0381] A board in which nine pieces of light emitting diode
elements were mounted was prepared. Each of the light emitting
diode elements was formed into a generally rectangular shape in
plane view. The size of each of the light emitting diode elements
was as follows: the thickness of 200 .mu.m and the length of 1
mm.times.1 mm. The gap between the light emitting diode elements
was 2 mm and the pitch thereof was 3 mm.
[0382] Thereafter, the encapsulating sheet was disposed at the
upper side of the board so that phosphor encapsulating layers were
opposed to the light emitting diode elements in the thickness
direction (ref: FIG. 6 (a)). Thereafter, the encapsulating sheet
was compressively bonded to the board so that each of the phosphor
encapsulating layers embedded each of the light emitting diode
elements (ref: FIG. 6 (b)). The conditions of the compression
bonding were as follows: the temperature of 130.degree. C., the
pressure of 0.1 MPa, and the duration of 10 minutes.
[0383] Then, the obtained product was heated at 150.degree. C. for
2 hours to be subjected to a post curing (after-curing).
[0384] To be specific, in Examples 1 and 3, by performing the post
curing, the silicone resin compositions in the phosphor
encapsulating layers were cured.
[0385] In Example 2, the silicone resin compositions in the
transparent layer and the phosphor encapsulating layer were
cured.
[0386] In Comparative Example 1, the silicone resin composition in
the phosphor encapsulating layer was cured.
[0387] In Comparative Example 2, the silicone resin composition in
the single layered sheet of a phosphor encapsulating layer was
cured.
[0388] In this way, a light emitting diode device in which the
light emitting diode elements were encapsulated by the
encapsulating sheet was produced.
[0389] (Evaluation)
[0390] 1. Mixing Amount of Phosphor
[0391] The mixing amount of the phosphor which was blended in one
piece of the encapsulating sheet in the light emitting diode device
was calculated. The results are shown in Table 1.
[0392] 2. Chromaticity
[0393] An electric current of 250 mA was applied through the light
emitting diode device, so that the light emitting diode elements
were allowed to light up and the CIE chromaticity diagram (y value)
thereof at the time was measured. The results are shown in Table
1.
[0394] 3. Appearance
[0395] An electric current of 250 mA was applied through the light
emitting diode device, so that the light emitting diode elements
were allowed to light up for 300 hours and the appearance (the
following 3-1. to 3-4.) thereof before and after the lighting up
test was measured, respectively.
[0396] The results are shown in Table 1.
[0397] 3-1. Coloring of Transparent Layer
[0398] Excellent: Coloring was not observed on the transparent
layer after the test.
[0399] Bad: Yellowing was observed on the transparent layer after
the test.
[0400] In Comparative Production Example 2, there was no
transparent layer and therefore, the present evaluation was not
conducted.
[0401] 3-2. Crack in Transparent Layer
[0402] Excellent: Crack was not observed in the transparent layer
after the test.
[0403] Bad: Crack was observed in the transparent layer after the
test.
[0404] 3-3. Peeling between Transparent Layer and Phosphor
Encapsulating Layer
[0405] Excellent: Peeling was not observed between the transparent
layer and the phosphor encapsulating layer after the test.
[0406] Good: Partial peeling was observed between the transparent
layer and the phosphor encapsulating layer after the test.
[0407] In Comparative Production Example 2, there was no
transparent layer and therefore, the present evaluation was not
conducted.
[0408] 3-4. Peeling between Encapsulating Sheet and Board
[0409] Excellent: Peeling was not observed between the
encapsulating sheet and the board after the test.
[0410] Good: Partial peeling was observed between the encapsulating
sheet and the board after the test. To be specific, the peeling was
observed on the interfacial surface between the transparent layer
and the board.
TABLE-US-00001 TABLE 1 Light Emitting Diode Device Ex. 1 Ex. 2 Ex.
3 Comp. Ex. 1 Comp. Ex. 2 Encapsulating Sheet Transparent Layer
Silicone Resin Silicone Resin Silicone Resin Epoxy Resin --
Composition in Composition in Composition in Composition in C-stage
State B-stage State C-stage State C-stage State Phosphor Phosphor +
Phosphor + Phosphor + Phosphor + Phosphor + Encapsulating Layer
Thermoplastic Thermoplastic Silicone Resin Silicone Resin Silicone
Resin Material of Material of Composition in Composition in
Composition in Silicone Resin Silicone Resin B-stage State B-stage
State State Composition Composition Amount of Phosphor Per One
Piece of 2.0 2.0 2.0 2.0 8.2 Encapsulating Sheet (mg) Chromaticity
(CIE, y Value) 0.34 0.34 0.34 0.34 0.35 Appearance Coloring of
Excellent Excellent Excellent Bad -- Transparent Layer Crack of
Transparent Excellent Excellent Excellent Bad Excellent Layer
Peeling between Excellent Excellent Excellent Good -- Transparent
Layer and Phosphor Encapsulating Layer Peeling between Good
Excellent Good Good Excellent Encapsulating Sheet and Board
[0411] While the illustrative embodiments of the present invention
are provided in the above description, such is for illustrative
purpose only and it is not to be construed as limiting the scope of
the present invention. Modification and variation of the present
invention that will be obvious to those skilled in the art is to be
covered by the following claims.
* * * * *