U.S. patent application number 16/500358 was filed with the patent office on 2020-11-12 for curing-reactive organopolysiloxane resin, pressure-sensitive adhesive composition using same, and use thereof.
The applicant listed for this patent is DOW TORAY CO., LTD.. Invention is credited to Maki ITOH, Akihiro NAKAMURA, Masahiro SAITO, Michitaka SUTO, Hidefumi TANAKA.
Application Number | 20200354615 16/500358 |
Document ID | / |
Family ID | 1000005007883 |
Filed Date | 2020-11-12 |
United States Patent
Application |
20200354615 |
Kind Code |
A1 |
ITOH; Maki ; et al. |
November 12, 2020 |
CURING-REACTIVE ORGANOPOLYSILOXANE RESIN, PRESSURE-SENSITIVE
ADHESIVE COMPOSITION USING SAME, AND USE THEREOF
Abstract
A curing-reactive organopolysiloxane composition is provided.
The composition generally forms a pressure-sensitive adhesive layer
which is curable by a hydrosilylation reaction, has excellent
adhesiveness and handleability, and is capable of maintaining high
transparency over an extended period of time without developing
problems such as discoloration or coloration, even when subjected
to long-term aging at a high temperature and even when exposed to
high-energy rays such as UV rays over an extended period of time.
The curing-reactive organopolysiloxane composition can be cured via
hydrosilylation reaction. A content of platinum-based metal among a
solid content is in the range of from 0.1 to 50 ppm. An adhesive
force of a cured layer with a thickness of 50 .mu.m obtained by
curing the composition is not less than 0.02N/25 mm. A
pressure-sensitive adhesive layer obtained by curing the
composition, and an electronic part or a display device using the
same, are also provided.
Inventors: |
ITOH; Maki; (Ichihara-shi,
Chiba, JP) ; TANAKA; Hidefumi; (Ichihara-shi, Chiba,
JP) ; NAKAMURA; Akihiro; (Ichihara-shi, Chiba,
JP) ; SAITO; Masahiro; (Ichihara-shi, Chiba, JP)
; SUTO; Michitaka; (Ichihara-shi, Chiba, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DOW TORAY CO., LTD. |
Shinagawa-ku, Tokyo |
|
JP |
|
|
Family ID: |
1000005007883 |
Appl. No.: |
16/500358 |
Filed: |
March 19, 2018 |
PCT Filed: |
March 19, 2018 |
PCT NO: |
PCT/JP2018/010769 |
371 Date: |
October 2, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 2307/202 20130101;
C09J 11/04 20130101; G06F 3/0414 20130101; C09J 7/38 20180101; B32B
2457/208 20130101; B32B 27/30 20130101; C09J 7/10 20180101; B32B
2307/412 20130101; B32B 2405/00 20130101; B32B 17/064 20130101;
C09J 2483/00 20130101; C09J 183/04 20130101; B32B 27/08 20130101;
B32B 2307/42 20130101 |
International
Class: |
C09J 183/04 20060101
C09J183/04; C09J 11/04 20060101 C09J011/04; C09J 7/38 20060101
C09J007/38; C09J 7/10 20060101 C09J007/10; G06F 3/041 20060101
G06F003/041; B32B 27/08 20060101 B32B027/08; B32B 17/06 20060101
B32B017/06; B32B 27/30 20060101 B32B027/30 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 3, 2017 |
JP |
2017-073475 |
Claims
1. A curing-reactive organopolysiloxane composition including a
hydrosilylation reaction, comprising a content of platinum-based
metal among a solid content within a range of from 0.1 to 50 ppm,
and an adhesive force of a polymethyl methacrylate sheet, with a
thickness of 2 mm provided with a cured layer with a thickness of
50 .mu.m obtained by curing the composition, as measured at a
tensile speed of 300 mm/min using a 180.degree. peel test method
according to JIS Z 0237, of not lower than 0.02 N/25 mm.
2. The curing-reactive organopolysiloxane composition according to
claim 1, wherein a b* value, which is measured with an L*a*b* color
system as prescribed in JIS Z 8729, of a cured layer with a
thickness of 100 .mu.m obtained by curing the composition is not
greater than 0.15.
3. The curing-reactive organopolysiloxane composition according to
claim 1 or 2, wherein when a cured layer with a thickness of 100
.mu.m obtained by curing the composition is aged for 300 hours at
105.degree. C. or irradiated for 75 hours with UV light using a
mercury lamp with an intensity of 12 mW/cm2 at 365 nm and an
intensity of 3.5 mW/cm2 at 254 nm, a change (.DELTA.b*) in a b*
value measured with an L*a*b* color system as prescribed in JIS Z
8729 is not greater than 0.20.
4. The curing-reactive organopolysiloxane composition according to
any one of claims 1 to 3, wherein a content of platinum-based metal
among solid content is in a range of from 0.1 to 30 ppm; a cured
layer with a thickness of 100 .mu.m obtained by curing the
composition is substantially transparent; a b*value thereof
measured with an L*a*b* color system as prescribed in JIS Z 8729 is
not greater than 0.10; and when the cured layer is aged for 300
hours at 105.degree. C. or irradiated for 75 hours with UV light
using a mercury lamp with an intensity of 12 mW/cm2 at 365 nm and
an intensity of 3.5 mW/cm2 at 254 nm, a change (.DELTA.b*) in a b*
value measured with an L*a*b* color system as prescribed in JIS Z
8729 is not greater than 0.15.
5. The curing-reactive organopolysiloxane composition according to
any one of claims 1 to 4, wherein the composition contains the
following components (A) to (C): (A) a straight-chain or
branched-chain organopolysiloxane having a number of alkenyl groups
greater than 1 on average in the molecule; (B) an
organopolysiloxane resin; and (C) an organohydrogenpolysiloxane
having at least two Si--H bonds in the molecule.
6. The curing-reactive organopolysiloxane composition according to
claim 5, wherein a molar ratio of silicon-bonded hydrogen atom
(SiH) groups in component (C) to alkenyl groups in the composition
is in a range of from 0.1 to 100.
7. The curing-reactive organopolysiloxane composition according to
claim 5 or 6, wherein at least a part of component (A) is (A1) a
raw rubber-like alkenyl group-containing organopolysiloxane having
a viscosity of not less than 100,000 mPa-s at 25.degree. C. or
having a plasticity in a range of from 50 to 200 as measured in
accordance with a method as prescribed in JIS K6249; at least a
part of component (B) is a resin which consists of (B1) R3SiO1/2
units (M units) and SiO4/2 units (Q units) and which may have a
hydroxyl group or a hydrolyzable group, wherein R is a monovalent
organic group and not less than 90 mol % of R is an alkyl group or
a phenyl group having a carbon number of from 1 to 6; and a content
of a vinyl (CH2.dbd.CH) portion in the alkenyl group in component
(A1) is in a range of from 0.005 to 0.400 wt. %, and a content of
component (B) is in a range of from 1 to 500 parts by mass with
respect to a total of 100 parts by mass of components (A) and (C)
in the composition.
8. The curing-reactive organopolysiloxane composition according to
any one of claims 1 to 7, further containing at least one type of
(D) curing retarder.
9. The curing-reactive organopolysiloxane composition according to
claim 8, wherein a viscosity of the composition after 8 hours at
room temperature from immediately after preparation of the
composition is not greater than 1.5 times that of a viscosity
immediately after the preparation of the composition, and the
composition is curable at 80 to 200.degree. C.
10. A pressure-sensitive adhesive composition comprising the
curing-reactive organopolysiloxane composition according to any one
of claims 1 to 9.
11. A cured product obtained by curing the curing-reactive
organopolysiloxane composition according to any one of claims 1 to
9.
12. A pressure-sensitive adhesive layer obtained by curing the
curing-reactive organopolysiloxane composition according to any one
of claims 1 to 9.
13. The pressure-sensitive adhesive layer according to claim 12,
which is film-like and substantially transparent.
14. A laminate comprising a cured product obtained by curing the
curing-reactive organopolysiloxane composition according to any one
of claims 1 to 9 on a film-like substrate.
15. The laminate according to claim 14, wherein the cured layer is
a pressure-sensitive adhesive layer, and a release layer for the
pressure-sensitive adhesive layer is provided on the film-like
substrate.
16. An electronic material or a member for a display device
obtained by curing the curing-reactive organopolysiloxane
composition according to any one of claims 1 to 9.
17. An electronic part or a display device containing the
electronic material or member for a display device according to
claim 16.
18. A display panel or a display comprising the film-like and
substantially transparent pressure-sensitive adhesive layer
according to claim 13.
19. A touch panel comprising a substrate having a conductive layer
formed on one surface; and a cured layer obtained by curing the
curing-reactive organopolysiloxane composition according to any one
of claims 1 to 9, which is attached to the conductive layer of the
substrate or a surface on an opposite side thereof.
20. The touch panel according to claim 19, wherein the substrate on
which the conductive layer is formed is a resin film or a glass
film having an ITO layer formed on one surface.
Description
TECHNICAL FIELD
[0001] The present invention relates to a curing-reactive
organopolysiloxane composition that is resistant to discoloration
and forms a transparent pressure-sensitive adhesive layer. More
particularly, the present invention relates to a curing-reactive
organopolysiloxane composition that forms a pressure-sensitive
adhesive layer capable of maintaining high transparency over an
extended period of time without developing problems such as
discoloration or coloration, even when subjected to long-term aging
at a high temperature and even when exposed to high-energy rays
such as UV rays over an extended period of time. In addition, the
present invention relates to a pressure-sensitive adhesive
composition that uses the curing-reactive organopolysiloxane
composition, and applications such as an electronic part or a
display device (including a touch panel) that use the
composition.
BACKGROUND ART
[0002] Polysiloxane pressure-sensitive adhesive compositions have
excellent electrical insulating properties, heat resistance, cold
resistance, and adhesion to various adherends in comparison to
acrylic or rubber-based pressure-sensitive adhesive compositions,
and are therefore used in heat-resistant adhesive tapes,
electrically insulating adhesive tapes, heat seal tapes, plating
masking tapes, and the like. These polysiloxane pressure-sensitive
adhesive compositions are classified into addition reaction curing
types, condensation reaction curing types, peroxide curing types,
and the like based on the curing mechanisms thereof. Addition
reaction curing type pressure-sensitive adhesive compositions are
widely used because the compositions cure quickly when left to
stand at room temperature or by heating and do not generate
by-products.
[0003] Taking advantage of the above characteristics and high
transparency of polysiloxane pressure-sensitive adhesives,
applications to the field of advanced electronic display elements
such as smart devices have been investigated in recent years. Such
a device assumes a structure in which a film made of a plurality of
layers including an electrode layer and a display layer is
sandwiched between transparent substrates, and a polysiloxane
pressure-sensitive adhesive having high heat resistance, cold
resistance, and transparency is expected to work effectively for
the purpose of protecting the electrode layer and the display layer
and improving adhesion between layers. For example, the structure
of an optically transparent silicone-based pressure-sensitive
adhesive film and a display device such as a touch panel using the
same is disclosed in Japanese Unexamined Patent Application
Publication (Translation of PCT Application) No. 2014-522436
(Patent Document 1), Japanese Unexamined Patent Application
Publication (Translation of PCT Application) No. 2013-512326
(Patent Document 2), and the like.
[0004] However, when a known silicone-based pressure-sensitive
adhesive is used in a display device such as a touch panel, an
adhesive layer formed from the silicone-based pressure-sensitive
adhesive may undergo coloration (including yellowing or loss of
transparency) in step with heat generation or light exposure from
the device main body or heat or light exposure originating from the
environment such as an on-board display, which may cause problems
such as the deterioration of display function or poor
appearance.
[0005] On the other hand, in the field of curable silicone
compositions other than pressure-sensitive adhesives, an
addition-curable silicone resin composition having reduced platinum
content (Patent Document 3) and a polysiloxane gel composition
(Patent Document 4) are known, and it has been disclosed that the
prevention of discoloration caused by the sulfurization of silver
plating serving as a substrate or the stability against
discoloration or changes in hardness caused by thermal degradation
of the silicone is improved. However, these compositions are
sealing materials or protective materials of semiconductors or the
like, and there has been no disclosure of any composition capable
of functioning as an adhesive layer or a pressure-sensitive
adhesive layer. Further, an organopolysiloxane composition capable
of forming an adhesive layer or a pressure-sensitive adhesive layer
by curing typically contains a silicone resin having low reactivity
and an organopolysiloxane having a high degree of polymerization as
main components in order to realize pressure-sensitive adhesion,
and the composition has a relatively low content of alkenyl groups
(carbon-carbon double bond moieties such as vinyl groups) and
density of alkenyl groups in the composition, and therefore, when
attempting to reduce the platinum content to the level described in
Patent Document 3 or the like (5 ppm or lower), problems with poor
curing may occur in a silicone-based pressure-sensitive adhesive.
Therefore, it is typical to not select such a low platinum level.
That is, the inventions disclosed in these documents differ from
the problems and technical fields of the present invention with
regard to the prevention of the discoloration of the transparent
adhesive layer itself formed from a silicone-based
pressure-sensitive adhesive, and it is not easy to apply the
technical elements thereof to a silicone pressure-sensitive
adhesive.
[0006] In contrast, in the field of silicone-based
pressure-sensitive adhesives, it has been proposed in Patent
Document 5 that by blending a reaction mixture of an alkenyl
group-containing polyorganosiloxane and a so-called MQ resin,
residual glue or discoloration can be prevented from occurring on a
substrate such as stainless steel when exposed to a high
temperature, in particular. However, in Patent Document 5, only a
very wide range such as from 5 to 2000 ppm is disclosed for the
amount of platinum that is used, and the "discoloration" in Patent
Document 5 is not that of the coloration of the pressure-sensitive
adhesive, and rather, is the coloration of the stainless steel
surface. The invention differs in the technical problem and
solution from the prevention of the discoloration of a transparent
adhesive layer itself formed from a silicone-based
pressure-sensitive adhesive, and it is difficult to solve this
problem.
[0007] Patent Document 6 proposes an addition type silicone
adhesive composition having a small degree of discoloration during
high-temperature exposure as a result of using a combination of a
(meth)acryloxyalkyl-modified organopolysiloxane and a zirconium
compound. However, it is not possible to form a transparent
adhesive layer because the addition type silicone adhesive
composition assumes a milky white color or the like, and therefore,
such cannot be applied to a display device or the like requiring
transparency, and only a very wide range such as 0.5 to 200 ppm is
disclosed for the amount of platinum that is used. In addition,
because the composition contains a (meth)acryloxyalkyl-modified
organopolysiloxane, problems with changes in hardness are likely to
occur in response to high-energy beams. Accordingly, the invention
differs in that the technical problem and solution involve
prevention of the discoloration of a transparent adhesive layer
itself formed from a silicone-based pressure-sensitive adhesive,
and it is difficult to solve this problem.
PRIOR ART DOCUMENTS
Patent Documents
[0008] Patent Document 1: Japanese Unexamined Patent Application
Publication (Translation of PCT Application) No. 2014-522436 [0009]
Patent Document 2: Japanese Unexamined Patent Application
Publication (Translation of PCT Application) No. 2013-512326 [0010]
Patent Document 3: Japanese Unexamined Patent Application
Publication No. S62-181357 [0011] Patent Document 4: Japanese
Unexamined Patent Application Publication No. 2010-248413 [0012]
Patent Document 5: Japanese Unexamined Patent Application
Publication No. 2006-213810 [0013] Patent Document 6: Japanese
Unexamined Patent Application Publication No. 2007-9189
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0014] The present invention was conceived in order to solve the
problems described above, and an object thereof is to provide a
curing-reactive organopolysiloxane composition that forms a
pressure-sensitive adhesive layer which is curable by a
hydrosilylation reaction, has excellent adhesiveness and
handleability, and is capable of maintaining high transparency over
an extended period of time without developing problems such as
discoloration or coloration, even when subjected to long-term aging
at a high temperature and even when exposed to high-energy rays
such as UV rays over an extended period of time. Another object of
the present invention is to provide a use of the curing-reactive
organopolysiloxane composition or a cured product thereof as a
pressure-sensitive adhesive layer, a use of the same as an
electronic material or a member for a display device, and an
electronic part or a display device provided with the same.
Means for Solving the Problems
[0015] As a result of conducting dedicated research on the problems
described above, the present inventors arrived at the present
invention. Specifically, one object of the present invention is
achieved by a curing-reactive organopolysiloxane composition
including a hydrosilylation reaction, wherein a content of
platinum-based metal among a solid content is in a range of from
0.1 to 50 ppm, and an adhesive force of a polymethyl methacrylate
sheet with a thickness of 2 mm provided with a cured layer with a
thickness of 50 .mu.m obtained by curing the composition, as
measured at a tensile speed of 300 mm/min using a 180.degree. peel
test method according to JIS Z 0237, is not less than 0.02 N/25 mm.
In addition, the problems described above can be solved by the use
of the curing-reactive organopolysiloxane composition or a cured
product thereof as a pressure-sensitive adhesive layer, the use of
the same as an electronic material or a member for a display
device, and an electronic part or a display device provided with
the same. Note that the solid content is a component that forms the
cured layer as a result of a curing reaction, and does not include
a volatile component such as a solvent.
[0016] That is, the present invention provides the following:
"[1] A curing-reactive organopolysiloxane composition including a
hydrosilylation reaction, wherein a content of platinum-based metal
among a solid content is in a range of from 0.1 to 50 ppm, and an
adhesive force of a polymethyl methacrylate sheet with a thickness
of 2 mm provided with a cured layer with a thickness of 50 .mu.m
obtained by curing the composition, as measured at a tensile speed
of 300 mm/min using a 180.degree. peel test method according to JIS
Z 0237, is not lower than 0.02 N/25 mm. [2] The curing-reactive
organopolysiloxane composition according to [1], wherein a b*
value, which is measured with an L*a*b* color system as prescribed
in JIS Z 8729, of a cured layer with a thickness of 100 .mu.m
obtained by curing the composition is not greater than 0.15. [3]
The curing-reactive organopolysiloxane composition according to [1]
or [2], wherein when a cured layer with a thickness of 100 .mu.m
obtained by curing the composition is aged for 300 hours at
105.degree. C. or irradiated for 75 hours with UV light using a
mercury lamp with an intensity of 12 mW/cm.sup.2 at 365 nm and an
intensity of 3.5 mW/cm.sup.2 at 254 nm, a change (.DELTA.b*) in a
b* value measured with an L*a*b* color system as prescribed in JIS
Z 8729 is not greater than 0.20. [4] The curing-reactive
organopolysiloxane composition according to any one of [1] to [3],
wherein a content of platinum-based metal among solid content is in
a range of from 0.1 to 30 ppm; a cured layer with a thickness of
100 .mu.m obtained by curing the composition is substantially
transparent; a b*value thereof measured with an L*a*b* color system
as prescribed in JIS Z 8729 is not greater than 0.10; and when the
cured layer is aged for 300 hours at 105.degree. C. or irradiated
for 75 hours with UV light using a mercury lamp with an intensity
of 12 mW/cm.sup.2 at 365 nm and an intensity of 3.5 mW/cm.sup.2 at
254 nm, a change (.DELTA.b*) in a b* value measured with an L*a*b*
color system as prescribed in JIS Z 8729 is not greater than 0.15.
[5] The curing-reactive organopolysiloxane composition according to
any one of [1] to [4], wherein the composition contains the
following components (A) to (C): (A) a straight-chain or
branched-chain organopolysiloxane having a number of alkenyl groups
greater than 1 on average in the molecule; (B) an
organopolysiloxane resin; and (C) an organohydrogenpolysiloxane
having at least two Si--H bonds in the molecule. [6] The
curing-reactive organopolysiloxane composition according to [5],
wherein a molar ratio of silicon-bonded hydrogen atom (SiH) groups
in component (C) to alkenyl groups in the composition is in a range
of from 0.1 to 100. [7] The curing-reactive organopolysiloxane
composition according to [5] or [6], wherein at least a part of
component (A) is (A1) a raw rubber-like alkenyl group-containing
organopolysiloxane having a viscosity of not less than 100,000
mPa-s at 25.degree. C. or having a plasticity in a range of from 50
to 200 as measured in accordance with a method as prescribed in JIS
K6249; at least a part of component (B) is a resin which consists
of (B1) R.sub.3SiO.sub.1/2 units (M units) and SiO.sub.4/2 units (Q
units) and may have a hydroxyl group or a hydrolyzable group,
wherein R is a monovalent organic group and not less than 90 mol %
of R is an alkyl group or a phenyl group having a carbon number of
from 1 to 6; and a content of a vinyl (CH.sub.2.dbd.CH) portion in
the alkenyl group in component (A1) is in a range of from 0.005 to
0.400 wt. %, and a content of component (B) is in a range of from 1
to 500 parts by mass with respect to a total of 100 parts by mass
of components (A) and (C) in the composition. [8] The
curing-reactive organopolysiloxane composition according to any one
of [1] to [7], further containing at least one type of (D) curing
retarder. [9] The curing-reactive organopolysiloxane composition
according to [8], wherein a viscosity of the composition after 8
hours at room temperature from immediately after preparation of the
composition is not greater than 1.5 times a viscosity immediately
after the preparation of the composition, and the composition is
curable at 80 to 200.degree. C. [10] A pressure-sensitive adhesive
composition including the curing-reactive organopolysiloxane
composition according to any one of [1] to [9]. [11] A cured
product obtained by curing the curing-reactive organopolysiloxane
composition according to any one of [1] to [9]. [12] A
pressure-sensitive adhesive layer obtained by curing the
curing-reactive organopolysiloxane composition according to any one
of [1] to [9]. [13] The pressure-sensitive adhesive layer according
to [12], which is film-like and substantially transparent. [14] A
laminate including a cured product obtained by curing the
curing-reactive organopolysiloxane composition according to any one
of [1] to [9] on a film-like substrate. [15] The laminate according
to [14], wherein the cured layer is a pressure-sensitive adhesive
layer, and a release layer for the pressure-sensitive adhesive
layer is provided on the film-like substrate. [16] An electronic
material or a member for a display device obtained by curing the
curing-reactive organopolysiloxane composition according to any one
of [1] to [9]. [17] An electronic part or a display device
containing the electronic material or member for a display device
according to [16]. [18] A display panel or a display including the
film-like and substantially transparent pressure-sensitive adhesive
layer according to [13]. [19] A touch panel including a substrate
having a conductive layer formed on one surface; and a cured layer
obtained by curing the curing-reactive organopolysiloxane
composition according to any one of [1] to [9], which is attached
to the conductive layer of the substrate or a surface on an
opposite side thereof. [20] The touch panel according to [19],
wherein the substrate on which the conductive layer is formed is a
resin film or a glass film having an ITO layer formed on one
surface.".
Effects of the Invention
[0017] The curing-reactive organopolysiloxane composition of the
present invention can form a pressure-sensitive adhesive layer
which is curable by a hydrosilylation reaction, has excellent
adhesiveness and handleability, and is capable of maintaining high
transparency over an extended period of time without developing
problems such as discoloration or coloration, even when subjected
to long-term aging at a high temperature and even when exposed to
high-energy rays such as UV rays over an extended period of time.
Further, the curing-reactive organopolysiloxane composition or a
cured product thereof can be suitably used as a pressure-sensitive
adhesive layer, an electronic material, or a member for a display
device, and an electronic component or display device provided with
the same can efficiently form a pressure-sensitive adhesive layer.
Therefore, industrial production is easy, and problems with
discoloration or coloration are unlikely to occur, even when the
transparent pressure-sensitive adhesive layer is heated or exposed
to high-energy rays, which yields the advantage that problems such
as the deterioration of display function or poor appearance are
unlikely to occur. In particular, a display device such as a
display panel, a display, or a touch panel obtained by providing a
pressure-sensitive adhesive layer obtained by curing the
organopolysiloxane composition of the present invention can be
provided.
MODE FOR CARRYING OUT THE INVENTION
Organopolysiloxane Composition
[0018] First, the curing-reactive organopolysiloxane composition of
the present invention will be described. The composition forms a
pressure-sensitive adhesive cured layer as a result of a curing
reaction including a hydrosilylation reaction, and does not develop
problems such as discoloration or coloration, even when subjected
to long-term aging at a high temperature and even when exposed to
high-energy rays such as UV rays over an extended period of
time.
Platinum-Based Metal Content
[0019] A first feature of such an organopolysiloxane composition is
that the composition is hydrosilylation reaction curable and that a
content of platinum-based metal among the solid content is within
the range of from 0.1 to 50 ppm. Platinum-based metal is a main
component of a hydrosilylation reaction catalyst and is a component
that promotes the curing of the composition of the present
invention, however at the same time, the platinum-based metal
causes discoloration or coloration of the pressure-sensitive
adhesive layer after curing when heated or exposed to high-energy
rays such as UV rays. Accordingly, the content of platinum-based
metal is preferably reduced as much as possible within a range that
does not adversely affect curability. Here, the platinum-based
metal is a metal element of group VIII consisting of platinum,
rhodium, palladium, ruthenium, and iridium, however, in practical
use, the content of the platinum-metal excluding the ligands of the
hydrosilylation catalyst is preferably within the range described
above. Note that the solid content is a component that forms the
cured layer (primarily a main agent, an adhesion-imparting
component, a crosslinking agent, a catalyst, and other non-volatile
components) when the organopolysiloxane composition of the present
invention is subjected to a curing reaction, and does not include
volatile components such as solvents that volatilize at the time of
heat curing.
[0020] On the other hand, the organopolysiloxane composition of the
present invention must form a pressure-sensitive adhesive cured
layer, and therefore typically contains an organopolysiloxane resin
and an organopolysiloxane containing an alkenyl group and has a
high degree of polymerization as a main component. These components
have a lower alkenyl group content in the molecule in comparison to
vinyl polysiloxanes or the like having a low degree of siloxane
polymerization used in silicone-based sealing agents and the like,
and the density of alkenyl groups in the composition tends to be
low, and therefore, if the content of the platinum-based metal in
the composition is low, curing defects may occur even when curing
is performed for a long period of time at a high temperature. In
addition, a pressure-sensitive adhesive layer is typically cured
industrially within 1 to 10 minutes, and it is often difficult to
employ a long curing process.
[0021] Preferably, the content of the platinum-based metal in the
organopolysiloxane composition of the present invention may be not
greater than 45 ppm, not greater than 35 ppm, not greater than 30
ppm, not greater than 25 ppm, or not greater than 20 ppm. When the
content of the platinum-based metal exceeds 50 ppm, this causes
discoloration or coloration of the transparent pressure-sensitive
adhesive layer, in particular, after curing or when heated or
exposed to high-energy rays such as UV rays. On the other hand,
from the perspective of the curability of the organopolysiloxane
composition, the content of the platinum-based metal is not lower
than 0.1 ppm, and when the content is lower than this lower limit,
this may cause curing defects. On the other hand, there is a demand
for a transparent pressure-sensitive adhesive layer to be formed by
a short curing reaction industrially, so even when the type of the
hydrosilylation reaction catalyst or curing retarder is optimized,
the content of the platinum-based metal in the composition may be
not lower than 0.5 ppm, not lower than 1.0 ppm, not lower than 2.0
ppm, or not lower than 3.0 ppm.
[0022] From the perspective of industrial production, it is
particularly preferable for content of the platinum-based metal in
the composition to be designed within the range of from 0.1 to 30
ppm, from 1.0 to 30 ppm, from 2.0 to 30 ppm, or from 3.0 to 25 ppm.
If the content is lower than the lower limit described above,
curing may not be possible in a short period of time even at an
industrially typical curing temperature (80 to 200.degree. C.),
whereas when the content exceeds the upper limit described above,
the discoloration or coloration of the transparent
pressure-sensitive adhesive layer may occur over a long period of
time, which may become a direct cause of the deterioration or
reduction of display function in the transparent pressure-sensitive
adhesive layer of a display device or the like.
Range of Pressure Sensitive Adhesion and Adhesive Force
[0023] The organopolysiloxane composition of the present invention
is characterized in that a cured layer obtained by curing the
composition by a hydrosilylation reaction is a pressure-sensitive
adhesive. Specifically, the adhesive force of a polymethyl
methacrylate sheet with a thickness of 2 mm provided with a cured
layer with a thickness of 50 .mu.m obtained by curing the
organopolysiloxane composition of the present invention, as
measured at a tensile speed of 300 mm/min using a 180.degree. peel
test method according to JIS Z 0237, is not lower than 0.02 N/25
mm. Note that the thickness (50 .mu.m) described above is the
thickness of the cured layer itself serving as a reference for
objectively defining the adhesive force of the cured layer of the
present invention. It goes without saying that the
organopolysiloxane composition of the present invention is not
limited to a thickness of 50 .mu.m and may be used as a cured layer
or a pressure-sensitive adhesive layer of any thickness.
[0024] For a cured layer with a thickness of 50 .mu.m, the function
as a pressure-sensitive adhesive layer is insufficient when the
adhesive force is lower than the lower limit described above. Note
that by using the components described above, a pressure-sensitive
adhesive layer having an adhesive force within the range of from
0.02 to 35 N/25 mm can typically be designed.
[0025] From the perspective of use as a pressure-sensitive adhesive
layer for a display device, in particular, a cured layer with a
thickness of 50 .mu.m preferably has an adhesive force of not lower
than 1.0 N/25 mm and more preferably not lower than 2.0 N/25 mm
under the conditions described above.
Properties Related to Transparency, Color Tone, and
Coloration/Discoloration of the Cured Layer
[0026] Due to the features described above, in particular, the fact
that the content of the platinum-based metal in the cured layer is
reduced, a cured layer using the organopolysiloxane composition of
the present invention is characterized in that the cured layer is
substantially transparent and is not colored immediately after
curing, and that, even when exposed to high temperatures or
high-energy beams such as UV rays over an extended period of time,
the color tone thereof does not change significantly, and there is
no loss of transparency. Specifically, the b* value, which is
measured with the L*a*b* color system as prescribed in JIS Z 8729,
immediately after curing a cured layer with a thickness of 100
.mu.m obtained by curing the organopolysiloxane composition of the
present invention is not greater than 0.15 and more preferably not
greater than 0.10. Having such a b* value means that the cured
layer is substantially transparent and is not colored yellow, and
when the b* value of a cured layer with a thickness of 100 .mu.m
exceeds the upper limit described above, the cured layer may not be
particularly suitable as a pressure-sensitive adhesive layer for a
display device due to problems with transparency or yellow
coloration. In addition, as a pressure-sensitive adhesive layer for
a display device, a film-like cured product with a thickness of
from 10 to 1000 .mu.m obtained by curing the organopolysiloxane
composition of the present invention must be visually transparent
for practical use. More objectively, when a value for air is 100%,
the transmittance of light at a wavelength of 450 nm of the
pressure-sensitive adhesive layer for a display device formed from
a cured layer with a thickness of 100 .mu.m is 80% or higher and
preferably 90% or higher when the value for air is 100%, and can be
easily designed to 95% or higher.
[0027] Even when the cured layer of the present invention is
exposed to high temperatures or high-energy beams such as UV rays
for an extended period of time, the color tone thereof does not
change significantly, and the problem of yellowing, in particular,
does not occur. Specifically, even if any of the following
evaluations are made, the change (.DELTA.b*) in the b* value
measured with the L*a*b* color system as prescribed in JIS Z 8729
immediately after evaluation, for a cured layer with a thickness of
100 .mu.m obtained by curing the organopolysiloxane composition of
the present invention, is not greater than 0.20 and preferably not
greater than 0.15. Note that .DELTA.b* is an absolute value of the
numerical change.
(1) Thermal aging evaluation: The cured layer is aged for 300 hours
at 105.degree. C. (2) High-energy beam irradiation: A sample of the
cured layer is irradiated for 75 hours at room temperature with UV
light using a mercury lamp (for example, Optical Module X or the
like manufactured by Ushio Electric Co., Ltd.) having an intensity
of 12 mW/cm.sup.2 at 365 nm and an intensity of 3.5 mW/cm.sup.2 at
254 nm.
Suitable Composition
[0028] As described above, the organopolysiloxane composition of
the present invention forms a pressure-sensitive adhesive layer
that is cured by a hydrosilylation reaction and has a certain
adhesive force, and the composition therefore preferably contains
at least the following components (A) to (C):
(A) a straight-chain or branched-chain organopolysiloxane having a
number of alkenyl groups greater than 1 on average in the molecule;
(B) an organopolysiloxane resin; and (C) an
organohydrogenpolysiloxane having at least two Si--H bonds in the
molecule.
[0029] In addition, since the composition contains a
hydrosilylation reaction catalyst, the composition preferably
further contains (D) a curing retarder from the perspective of
handleability, and may further contain other additives to an extent
that is not at odds with the object of the present invention.
Hereinafter, each component will be described.
[0030] The alkenyl group-containing organopolysiloxane of component
(A) is the main agent (base polymer) of this composition and
contains an alkenyl group bonded to a number of silicon atoms
greater than 1 on average in each molecule, and the preferable
number of alkenyl groups is not less than 1.5 groups in each
molecule. Examples of the alkenyl groups of the organopolysiloxane
of component (A) include alkenyl groups having a carbon number of
from 2 to 10 such as vinyl groups, allyl groups, butenyl groups,
pentenyl groups, hexenyl groups, and heptenyl groups, and vinyl
groups or hexenyl groups are particularly preferable. Examples of
the bonding position of the alkenyl groups of component (A) include
the molecular chain terminals and/or the molecular side chains.
Note that component (A) may contain a single component or may be a
mixture of two or more different components.
[0031] Examples of silicon-bonded organic groups other than alkenyl
groups in the organopolysiloxane of component (A) include alkyl
groups such as methyl groups, ethyl groups, propyl groups, butyl
groups, pentyl groups, hexyl groups, and heptyl groups; aryl groups
such as phenyl groups, tolyl groups, xylyl groups, and naphthyl
groups; aralkyl groups such as benzyl groups and phenethyl groups;
and halogenated alkyl groups such as chloromethyl groups,
3-chloropropyl groups, and 3,3,3-trifluoropropyl groups; and methyl
groups and phenyl groups are particularly preferable.
[0032] The molecular structure of component (A) is preferably a
straight chain or partially branched straight chain, and may
partially include a cyclic, three-dimensional network. Preferably,
the main chain consists of repeating diorganosiloxane units and is
preferably a straight-chain or branched-chain diorganopolysiloxane
capped at both molecular terminals with triorganosiloxy groups.
Note that the siloxane units that provide a branched-chain
organopolysiloxane are T units or Q units described below.
[0033] The properties of component (A) at room temperature may be
those of an oily or raw rubber-like substance, and the viscosity of
component (A) is not lower than 50 mPa-s and particularly
preferably not lower than 100 mPa-s at 25.degree. C. In particular,
when the curable silicone composition is a solvent type, at least a
part of component (A) is (A1) a raw rubber-like alkenyl
group-containing organopolysiloxane having a viscosity of not less
than 100,000 mPa-s at 25.degree. C. or having a plasticity (value
when a load of 1 kgf is applied for 3 minutes to a 4.2 g spherical
sample at 25.degree. C.) in a range of from 50 to 200 as measured
in accordance with the method as prescribed in JIS K6249. Even a
component (A) with a lower viscosity may be used, however, from the
perspective of the technical effects of the present invention,
preferably at least 50 mass % of component (A) will be an alkenyl
group-containing organopolysiloxane with a high degree of
polymerization, which is component (A1), and it is particularly
preferable for 75 to 100 mass % of the component to be component
(A1).
[0034] Although the content of alkenyl groups in component (A1) is
not particularly limited, from the perspective of the technical
effects of the present invention, the content of the vinyl
(CH.sub.2.dbd.CH) portion in the alkenyl groups in component (A1)
(called the "vinyl content" hereinafter) is preferably in the range
of from 0.005 to 0.400 wt. % and particularly preferably in the
range of from 0.005 to 0.300 wt. %.
[0035] The organopolysiloxane resin (B) is an adhesion-imparting
component that imparts an adhesive force to the substrate, and is
not particularly limited as long as the organopolysiloxane has a
three-dimensional structure. Examples include a resin consisting of
R.sub.2SiO.sub.2/2 units (D units) and RSiO.sub.3/2 units (T units)
(wherein each R independently represents a monovalent organic
group) and having or not having a hydroxyl group or a hydrolyzable
group, a resin consisting of only T units and having or not having
a hydroxyl group or a hydrolyzable group, and a resin consisting of
R.sub.3SiO.sub.1/2 units (M units) and SiO.sub.4/2 units (Q units)
and having or not having a hydroxyl group or a hydrolyzable group.
In particular, it is preferable to use (B1) a resin consisting of
R.sub.3SiO.sub.1/2 units (M units) and SiO.sub.4/2 units (Q units)
and having a hydroxyl group or a hydrolyzable group (also called an
MQ resin). The hydroxyl groups or hydrolyzable groups are directly
bonded to silicon of the T units or Q units in the resin, and are
groups derived from silane as a raw material or generated as a
result of hydrolysis of silane.
[0036] The monovalent organic group of R is preferably a monovalent
hydrocarbon group having a carbon number of from 1 to 10, examples
of which include alkyl groups having a carbon number of from 1 to
10, alkenyl groups having a carbon number of from 2 to 10, aryl
groups having a carbon number of from 6 to 10, cycloalkyl groups
having a carbon number of from 6 to 10, benzyl groups, phenylethyl
groups, and phenylpropyl groups. In particular, preferably at least
90 mol % of R will be an alkyl group or a phenyl group having a
carbon number of from 1 to 6, and it is particularly preferable for
from 95 to 100 mol % of R to be a methyl group or a phenyl
group.
[0037] When the organopolysiloxane resin (B) is a resin consisting
of R.sub.3SiO.sub.1/2 units (M units) and SiO.sub.4/2 units (Q
units), the molar ratio of M units to Q units is preferably from
0.5 to 2.0. This is because when the molar ratio is less than 0.5,
the adhesive force to the substrate may be diminished, whereas when
the molar ratio is greater than 2.0, the cohesive strength of the
material constituting the adhesive layer decreases. In addition, D
units and Q and T units may also be included in component (B) to an
extent that does not impair the characteristics of the present
invention, and component (B) may use a combination of two or more
types of organopolysiloxanes. The organopolysiloxane resin (B) may
have a hydroxyl group or a hydrolyzable group, and a resin having a
hydroxyl group or a hydrolyzable group, a resin not having a
hydroxyl group or a hydrolyzable group, or a mixture thereof may be
used without restriction. When this organopolysiloxane resin has a
hydroxyl group or a hydrolyzable group, the resin ordinarily
contains from 0.1 to 5.0 mass % of hydroxyl groups or hydrolyzable
groups.
[0038] Component (C) is an organohydrogenpolysiloxane having two or
more Si--H bonds in the molecule and is a crosslinking agent of the
organopolysiloxane composition of the present invention. The
molecular structure of component (C) is not particularly limited,
and examples thereof include a straight chain, a partially branched
straight chain, a branched chain, a cyclic, or an
organopolysiloxane resin structure, and a straight chain, a
partially branched straight chain, or an organopolysiloxane resin
structure is preferable. The bonding position of silicon-bonded
hydrogen atoms is not particularly limited, and examples thereof
include molecular terminals, side chains, and both molecular
terminals and side chains.
[0039] The content of the silicon-bonded hydrogen atoms is
preferably from 0.1 to 2.0 wt. % and more preferably from 0.5 to
1.7 wt. %.
[0040] Examples of silicon-bonded organic groups include alkyl
groups having a carbon number of from 1 to 8 such as methyl groups,
ethyl groups, propyl groups, butyl groups, and octyl groups; aryl
groups such as phenyl groups and tolyl groups; aralkyl groups such
as benzyl groups and phenethyl groups; and halogenated alkyl groups
such as 3-chloropropyl groups and 3,3,3-trifluoropropyl groups;
however, preferably at least 50 mol % of the total number of these
groups will be alkyl groups or phenyl groups having a carbon number
of from 1 to 8. From the perspective of ease of manufacture and
compatibility with the preferred components (A) and (B) described
above, the other organic groups are preferably methyl groups or
phenyl groups.
[0041] When component (C) of the present invention is an
organohydrogenpolysiloxane, which is an organopolysiloxane resin,
examples thereof include organopolysiloxane copolymers consisting
of siloxane units represented by the general formula:
R'.sub.3SiO.sub.1/2, siloxane units represented by the general
formula R'.sub.2HSiO.sub.1/2, and siloxane units represented by the
formula: SiO.sub.412;
[0042] organopolysiloxane copolymers consisting of siloxane units
represented by the general formula: R'.sub.2HSiO.sub.1/2 and
siloxane units represented by the formula: SiO.sub.4/2;
organopolysiloxane copolymers consisting of siloxane units
represented by the general formula: R'.sub.2HSiO.sub.1/2 and
siloxane units represented by the formula: R''SiO.sub.3/2;
organopolysiloxane copolymers consisting of siloxane units
represented by the general formula: R'HSiO.sub.2/2, siloxane units
represented by the general formula: R'SiO.sub.3/2, or siloxane
units represented by the formula: HSiO.sub.3/2; and mixtures of two
or more types of these organopolysiloxanes. Note that R' in the
formulas is an alkyl group having a carbon number of from 1 to 8,
an aryl group, an aralkyl group, or a halogenated alkyl group, and
examples thereof are the same as those described above.
[0043] Specific examples of component (C) include
tris(dimethylhydrogensiloxy)methylsilane,
tetra(dimethylhydrogensiloxy)silane, methylhydrogenpolysiloxanes
capped at both terminals with trimethylsiloxy groups,
dimethylsiloxane/methylhydrogensiloxane copolymers capped at both
terminals with trimethylsiloxy groups,
dimethylsiloxane/methylhydrogensiloxane copolymers capped at both
terminals with dimethylhydrogensiloxy groups, cyclic methylhydrogen
oligosiloxanes, cyclic methylhydrogensiloxane/dimethylsiloxane
copolymers, methylhydrogensiloxane/diphenylsiloxane copolymers
capped at both molecular terminals with trimethylsiloxy groups,
methylhydrogensiloxane/diphenylsiloxane/dimethylsiloxane copolymers
capped at both molecular terminals with trimethylsiloxy groups,
hydrolytic condensates of trimethylsilanes, copolymers consisting
of (CH.sub.3).sub.2HSiO.sub.1/2 units and SiO.sub.4/2 units,
copolymers consisting of (CH.sub.3).sub.2HSiO.sub.1/2 units,
SiO.sub.4/2 units, and (C.sub.6H.sub.5)SiO.sub.3/2 units,
copolymers consisting of (CH.sub.3).sub.2HSiO.sub.1/2 units and
CH.sub.3SiO.sub.3/2 units, and mixtures of two or more types
thereof.
[0044] In the case of a straight-chain structure, in particular, a
methylhydrogenpolysiloxane represented by the molecular structural
formula:
R.sup.TMe.sub.2SiO(Me.sub.2SiO).sub.q(HMeSiO).sub.rSiMe.sub.2R.s-
up.T (7)
(wherein Me is a methyl group, RT is a methyl group or a hydrogen
atom, and q and r are numbers satisfying
0.3.ltoreq.r/(q+r).ltoreq.1 and 10.ltoreq.(q+r).ltoreq.200) is
preferable. Note that component (C) may use two or more different
types in combination.
[0045] Similarly, the following such organosiloxanes may be given
as examples. Note that in the formulas, Me and Ph respectively
represent a methyl group and a phenyl group, m is an integer from 1
to 100, n is an integer from 1 to 50, and b, c, d, and e are each
positive numbers, where the sum of b, c, d, and e in one molecule
is 1.
HMe.sub.2SiO(Ph.sub.2SiO).sub.mSiMe.sub.2H
HMePhSiO(Ph.sub.2SiO).sub.mSiMePhH
HMePhSiO(Ph.sub.2SiO).sub.m(MePhSiO).sub.nSiMePhH
HMePhSiO(Ph.sub.2SiO).sub.m(Me.sub.2SiO).sub.nSiMePhH
(HMe.sub.2SiO.sub.1/2).sub.b(PhSiO.sub.3/2).sub.c
(HMePhSiO.sub.1/2).sub.b(PhSiO.sub.3/2).sub.c
(HMePhSiO.sub.1/2).sub.b(HMe.sub.2SiO.sub.1/2).sub.c(PhSiO.sub.3/2).sub.-
d
(HMe.sub.2SiO.sub.1/2).sub.b(Ph.sub.2SiO.sub.2/2).sub.c(PhSiO.sub.3/2).s-
ub.d
(HMePhSiO.sub.1/2).sub.b(Ph.sub.2SiO.sub.2/2).sub.c(PhSiO.sub.3/2).sub.d
(HMePhSiO.sub.1/2).sub.b(HMe.sub.2SiO.sub.1/2).sub.c(Ph.sub.2SiO.sub.2/2-
).sub.d(PhSiO.sub.3/2).sub.e
[0046] The amount of component (C) that is used may be such that
the molar ratio of silicon-bonded hydrogen atom (SiH) groups in
component (C) to the alkenyl groups in the composition is in a
range of from 0.1 to 100, a range of from 0.1 to 50, or a range of
from 0.1 to 20. When the amount of the SiH groups falls below the
lower limit described above, this may cause curing defects in the
composition, whereas when the amount of the SiH groups exceeds the
upper limit described above, the amount of unreacted residual
curing agent becomes large, which may have adverse effects on
curing physical properties such as brittleness of the cured product
or may cause problems such as gas generation.
[0047] From the perspective of the technical effects of the present
invention and, in particular, use as a pressure-sensitive adhesive
layer, a mass ratio is preferably from 1 to 50 parts by mass and
more preferably from 30 to 400 parts by mass with respect to a
total of 100 parts by mass of components (A) and (C) in the
composition. This is because when the content of component (B) is
lower than the lower limit described above or exceeds the upper
limit described above, the adhesive force may be insufficient.
Hydrosilylation Reaction Catalyst
[0048] The organopolysiloxane composition of the present invention
contains a hydrosilylation reaction catalyst. Examples of
hydrosilylation reaction catalysts include platinum-based
catalysts, rhodium-based catalysts, and palladium-based catalysts,
and platinum-based catalysts are preferable in that they markedly
accelerate the curing of the present composition. Examples of this
platinum based catalyst include platinum fine powder,
chloroplatinic acid, an alcohol solution of chloroplatinic acid, a
platinum-alkenyl siloxane complex, a platinum-olefin complex, and a
platinum-carbonyl complex, with a platinum-alkenyl siloxane complex
particularly preferable. Examples of this alkenyl siloxane include
1,3-divinyl-1,1,3,3-tetramethyldisiloxane,
1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, alkenyl
siloxanes in which some of the methyl groups of these alkenyl
siloxanes are substituted with groups selected from the group
consisting of nitriles, amides, dioxolanes, and sulfolanes, ethyl
groups, phenyl groups, or the like, and alkenyl siloxanes in which
the vinyl groups of these alkenyl siloxanes are substituted with
allyl groups, hexenyl groups, or the like. In particular,
1,3-divinyl-1,1,3,3-tetramethyldisiloxane is preferable in that the
stability of the platinum-alkenyl siloxane complex is good. As the
catalyst for promoting the hydrosilylation reaction, a non-platinum
based metal catalyst such as iron, ruthenium, iron/cobalt, or the
like may be used.
[0049] In the present invention, a content of the hydrosilylation
reaction catalyst is in a range such that the amount of
platinum-based metal is in the range of from 0.1 to 50 ppm with
respect to the total amount of the solid content in the
composition, and this preferable range is as described in
"Platinum-based metal content" above. In general, as described
above, in order to ensure the function as a pressure-sensitive
adhesive layer in a silicone-based pressure-sensitive adhesive, the
use of an alkenyl group-containing organopolysiloxane with a high
degree of polymerization and an MQ resin with low reactivity is
preferable for the composition. Therefore, the amount of platinum
metal is often designed to at most the upper limit described above
from the perspective of curability, but a curing-reactive
organopolysiloxane composition which sufficiently exhibits a
function as a pressure-sensitive adhesive layer even when the
amount of platinum is reduced can be provided as a result of a
compositional design which utilizes/optimizes (D) a curing
retarder.
[0050] Component (D) is a curing retarder and is compounded in
order to suppress crosslinking reactions between the alkenyl groups
in the composition and the SiH groups in component (C) so as to
extend the usable life at ordinary temperatures and to enhance the
storage stability. Accordingly, in practical use, the component is
nearly essential to the curing-reactive organopolysiloxane
composition of the present invention.
[0051] Specific examples of component (D) include acetylenic
compounds, ene-yne compounds, organic nitrogen compounds, organic
phosphorus compounds, and oxime compounds. Specific examples
include alkyne alcohols such as 3-methyl-1-butyne-3-ol,
3,5-dimethyl-1-hexyne-3-ol, 3-methyl-1-pentyne-3-ol,
1-ethynyl-1-cyclohexanol, and phenyl butanol; ene-yne compounds
such as 3-methyl-3-pentene-1-yne and 3,5-dimethyl-1-hexyne-3-yne;
methylalkenylcyclosiloxanes such as
1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and
1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane; and
benzotriazoles.
[0052] From the perspective of the curing behavior of the
composition, the curing-reactive organopolysiloxane composition of
the present invention is preferably curable at 80 to 200.degree. C.
with an increase in viscosity of 1.5 times after 8 hours at room
temperature after the preparation of the composition. The
suppression of thickening is important from the perspective of
handleability, pot life, and characteristics after curing, and even
if the content of the platinum-based metal is low, the curability
can be ensured by curing at high temperature of at least a certain
temperature (80 to 200.degree. C.). Note that such a composition
can be realized by selecting a suitable combination and compounded
amounts of each of the components described above, the
hydrosilylation catalyst, and component (D).
[0053] In addition to the preferred components (A) and (B)
described above, the organopolysiloxane composition of the present
invention may also contain an organic solvent as a solvent. The
type and compounded amount of the organic solvent are adjusted out
of consideration of application workability or the like. Examples
of organic solvents include aromatic hydrocarbon-based solvents
such as toluene, xylene, and benzene; aliphatic hydrocarbon-based
solvents such as heptane, hexane, octane, and isoparaffin;
ester-based solvents such as ethyl acetate and isobutyl acetate;
ether-based solvents such as diisopropyl ether and 1,4-dioxane;
chlorinated aliphatic hydrocarbon-based solvents such as
trichloroethylene, perchloroethylene, and methylene chloride; and
solvent volatile oils; and two or more types may be combined in
accordance with the wettability of the sheet-like substrate or the
like. A compounded amount of the organic solvent is preferably an
amount such that a mixture of components (A) to (C) can be
uniformly applied to a sheet-like substrate surface. For example,
the compounded amount may be from 5 to 300 parts by mass per total
of 100 parts by mass of components (A), (B), and (C).
[0054] The organopolysiloxane composition of the present invention
may optionally contain components other than the components
described above to an extent that does not impair the technical
effects of the present invention. For example, the composition may
contain: an adhesion promoter; a non-reactive organopolysiloxane
such as a polydimethylsiloxane or a polydimethyldiphenylsiloxane;
an antioxidant such as a phenol-type, a quinone-type, an
amine-type, a phosphorus-type, a phosphite-type, a sulfur-type, or
a thioether-type antioxidant; a flame retardant such as a phosphate
ester-type, a halogen-type, a phosphorus-type, or an antimony-type
flame retardant; and one or more types of antistatic agents
consisting of a cationic surfactant, an anionic surfactant, a
non-ionic surfactant, or the like. Note that in addition to these
components, pigments, dyes, inorganic fine particles, or the like
may be optionally compounded, however, it is preferable to avoid
compounding optional components that diminish optical properties
such as transparency or cause coloration of the pressure-sensitive
adhesive layer.
[0055] The method of preparing the organopolysiloxane composition
of the present invention is not particularly limited and is
performed by homogeneously mixing the respective components. A
solvent may be added as necessary, and the composition may be
prepared by mixing at a temperature of from 0 to 200.degree. C.
using a known stirrer or kneader.
[0056] The organopolysiloxane composition of the present invention
forms a coating film when applied to a substrate and forms a cured
product by heating under temperature conditions of from 80 to
200.degree. C. and preferably under temperature conditions of from
90 to 190.degree. C. Examples of application methods include
gravure coating, offset coating, offset gravure, roll coating,
reverse roll coating, air knife coating, curtain coating, and comma
coating.
Use as a Pressure-Sensitive Adhesive Layer
[0057] The cured product of the present invention can be used as a
substantially transparent pressure-sensitive adhesive layer, in
particular. Here, substantially transparent means that the
composition is visually transparent when a film-shaped cured
product with a thickness of from 10 to 1000 .mu.m is formed. In
general, for a film-like cured product with a thickness of 100
.mu.m, the transmittance of light at a wavelength of 450 nm is 80%
or higher and preferably 90% or higher when the value for air is
100%, and can be easily designed to 95% or higher. In addition, in
order to improve adhesion with the adherend, surface treatment such
as primer treatment, corona treatment, etching treatment, or plasma
treatment may be performed on the surface of the pressure-sensitive
adhesive layer or the substrate.
[0058] The curable organopolysiloxane composition of the present
invention is cured by applying the composition to a release liner,
then heating under the temperature conditions described above, and
then, after the release liner is peeled off and the composition is
attached to a film-like substrate, a tape-like substrate, or a
sheet-like substrate (called a "film-like substrate" hereinafter)
or applied to a film-like substrate, curing by heating at the
temperature conditions described above so as to form a
pressure-sensitive adhesive layer on the surface of the substrate.
A laminate provided with a cured layer--in particular, a film-like
pressure-sensitive adhesive layer--obtained by curing the
organopolysiloxane composition of the present invention on these
film-like substrates may be used for adhesive tapes, adhesive
bandages, low-temperature supports, transfer films, labels,
emblems, and decorative or explanatory signs. Further, a cured
layer obtained by curing the organopolysiloxane composition of the
present invention may be used to assemble automobile parts, toys,
electronic circuits, or keyboards. Alternatively, a cured layer
formed by curing the organopolysiloxane composition of the present
invention, and particularly a film-like pressure-sensitive adhesive
layer, may be used in the construction and use of a laminated touch
screen or flat panel display.
[0059] Examples of types of substrates include paperboard,
cardboard paper, clay-coated paper, polyolefin laminate paper,
polyethylene laminate paper in particular, synthetic resin films
and sheets, natural fiber cloth, synthetic fiber cloth, artificial
leather cloth, and metal foil. In particular, synthetic resin films
and sheets are preferable, and examples of synthetic resins include
polyimides, polyethylenes, polypropylenes, polystyrenes, polyvinyl
chlorides, polyvinylidene chlorides, polycarbonates, polyethylene
terephthalates, cyclopolyolefins, and nylons. In particular, when
heat resistance is required, a heat-resistant synthetic resin film
such as a polyimide, polyetheretherketone, polyethylene naphthalate
(PEN), liquid crystal polyacrylate, polyamide-imide, or polyether
sulfone is suitable. On the other hand, in applications such as a
display device in which visibility is required, a transparent
substrate--specifically, a transparent material such as a
polypropylene, polystyrene, polyvinylidene chloride, polycarbonate,
polyethylene terephthalate, or PEN--is suitable.
[0060] The substrate described above is preferably a film-like or a
sheet-like substrate. A thickness thereof is not particularly
limited and can be designed with a desired thickness in accordance
with the application. Further, in order to improve adhesion between
a support film and the pressure-sensitive adhesive layer, a support
film subjected to primer treatment, corona treatment, etching
treatment, or plasma treatment may be used. In addition, the
surface of the film-like substrate on the opposite side as the
pressure-sensitive adhesive layer surface may be subjected to
surface treatment such as scratch prevention, anti-soiling,
fingerprint adhesion prevention, anti-glare, anti-reflection, or
anti-static treatment.
[0061] As the application method to the substrate, gravure coating,
offset coating, offset gravure, roll coating using an offset
transfer roll coater, reverse roll coating, air knife coating,
curtain coating using a curtain flow coater or the like, comma
coating, meyer bar, or another known method used for the purpose of
forming a cured layer may be used without limitation.
[0062] The coating amount can be designed at a desired thickness in
accordance with the application such as a display device, and when
used as a transparent pressure-sensitive adhesive layer, in
particular, the thickness of the pressure-sensitive adhesive layer
after curing may be from 1 to 1000 .mu.m, from 5 to 900 .mu.m, or
from 10 to 800 .mu.m, however, there is no limitation thereto.
[0063] When the cured layer obtained by curing the
organopolysiloxane composition of the present invention is a
pressure-sensitive adhesive layer, in particular, a substantially
transparent pressure-sensitive adhesive layer, the cured layer is
preferably treated as a laminate film that is peelably adhered to a
film substrate provided with a release layer having a
release-coating capability.
[0064] The cured product obtained by curing the organopolysiloxane
composition of the present invention is useful as an electronic
material, a member for a display device, or a member for a
transducer (including sensors, speakers, actuators, and
generators), and a suitable application for the cured product is a
member for an electronic part or a display device. In particular, a
film-shaped cured product, particularly a substantially transparent
pressure-sensitive adhesive film, is suitable as a member for a
display panel or a display, and is particularly useful in so-called
touch panel applications in which a device, particularly an
electronic device, can be operated by touching a screen with a
fingertip or the like.
[0065] In particular, a pressure-sensitive adhesive layer obtained
by curing the organopolysiloxane composition of the present
invention has excellent transparency and does not develop problems
with discoloration or coloration, even when exposed to high
temperatures or high-energy beams for a long period of time.
Therefore, a display apparatus or display device with excellent
high-temperature durability or weather resistance can be designed,
and a display apparatus or display device with excellent visibility
can be realized by suppressing decreases in screen display function
over a long period of time.
Member for Display Panel or Display
[0066] A cured product obtained by curing the organopolysiloxane
composition of the present invention can be used in the
construction and use of a laminated touch screen or flat panel
display, and the specific method of use thereof may be a known
method of use of a pressure-sensitive adhesive layer (in
particular, silicone PSA) without any particular limitation. For
example, a cured product obtained by curing the organopolysiloxane
composition of the present invention can be used in the production
of a display device such as a touch panel as an optically
transparent silicone-based pressure-sensitive adhesive film or an
adhesive layer disclosed in Japanese Unexamined Patent Application
Publication (Translation of PCT Application) No. 2014-522436
(Patent Document 1) or Japanese Unexamined Patent Application
Publication (Translation of PCT Application) No. 2013-512326
(Patent Document 2) described above. Specifically, the cured
product obtained by curing the organopolysiloxane composition of
the present invention can be used as the adhesive layer or adhesive
film described in Patent Document 2 without any particular
limitation.
[0067] As an example, the touch panel according to the present
invention may be a touch panel including a substrate such as a
conductive plastic film having a conductive layer formed on one
surface, and a cured layer obtained by curing the curable
organopolysiloxane composition of the present invention, which is
attached to a surface on the side where the conductive layer is
formed or on the opposite side thereof. The substrate is preferably
a sheet-like or film-like substrate, and an example thereof is a
resin film or a glass plate. In addition, the conductive plastic
film may be a resin film or a glass plate, in particular, a
polyethylene terephthalate film, having an ITO layer formed on one
surface thereof. These are disclosed in Japanese Unexamined Patent
Application Publication No. (Translation of PCT Application)
2013-512326 (Patent Document 2) and the like described above.
[0068] In addition, a cured product obtained by curing the
organopolysiloxane composition of the present invention may be used
as an adhesive film for a polarizing plate used in the production
of a display device such as a touch panel, or may be used as a
pressure-sensitive adhesive layer used in bonding between a touch
panel and a display module described in Japanese Unexamined Patent
Application Publication No. 2013-065009.
INDUSTRIAL APPLICABILITY
[0069] Applications of the curing-reactive organopolysiloxane
composition and a cured product obtained by curing the same
according to the present invention are in no way limited to the
disclosure above, and a pressure-sensitive adhesive film provided
with a cured product obtained by curing the composition can be used
in various display devices for displaying characters, symbols, and
images such as television receivers, computer monitors, monitors
for personal digital assistants, monitoring monitors, video
cameras, digital cameras, mobile phones, personal digital
assistants, displays for instrument panels of automobiles or the
like, displays for instrument panels of various equipment, devices,
and instruments, automatic ticket machines, automated teller
machines, on-board display devices, and on-board transmission
screens. The surface shape of such a display device may be a curved
shape or a bowed shape rather than a flat surface, and examples
thereof include curved displays or curved transmission screens used
in automobiles (including electric vehicles), aircraft, or the like
in addition to various flat panel displays (FPDs). Further, these
display devices can display icons for executing functions or
programs on a screen or display, notification indicators of e-mail,
programs, or the like, and operation buttons for various devices
such as car navigation devices, audio devices, and air conditioning
devices, and touch panel functions enabling input operations may be
added by touching these icons, notification indicators, or
operation buttons with a finger. As a device, the present invention
can be applied to display devices such as CRT displays, liquid
crystal displays, plasma displays, organic EL displays, inorganic
EL displays, LED displays, surface electrolytic displays (SEDs),
and field emitting displays (FEDs), or touch panels utilizing the
same.
[0070] A pressure-sensitive adhesive layer obtained by curing the
curing-reactive organopolysiloxane composition of the present
invention has excellent adhesiveness and handleability and is
capable of maintaining high transparency over an extended period of
time without developing problems such as discoloration or
coloration even when subjected to long-term aging at a high
temperature and even when exposed to high-energy rays such as UV
rays over an extended period of time. Therefore, the
pressure-sensitive adhesive layer can be suitably used in a vehicle
display device with excellent visibility and operability of the
display content over an extended period of time, and in particular,
a vehicle display device having a curved screen or a curved display
and optionally equipped with a touch panel function. For example,
vehicle display devices equipped with curved display surfaces are
disclosed in Japanese Unexamined Patent Application Publication No.
2017-047767, Japanese Unexamined Patent Application Publication No.
2014-182335, Japanese Unexamined Patent Application Publication No.
2014-063064, Japanese Unexamined Patent Application Publication No.
2013-233852, and the like, however, the pressure-sensitive adhesive
layer of the present invention can be suitably applied or replaced
as part or all of an adhesive layer or a pressure-sensitive
adhesive layer for which transparency is required in these
documents. Further, it goes without saying that currently used
adhesive layers or pressure-sensitive adhesive layers requiring
transparency may be used as a substitute for other known curved
display devices as well, and in order to further leverage the
advantages of the pressure-sensitive adhesive of the present
invention, it is preferable to adjust the design of the display
device or the thickness of the member using known techniques.
[0071] Note that a transparent film-like substrate provided with
the pressure-sensitive adhesive layer of the present invention may
be used for the purpose of scratch prevention, dirt prevention,
fingerprint adhesion prevention, static prevention, glare
prevention, peep prevention, and the like of these display
surfaces.
EXAMPLES
[0072] Examples of the present invention and comparative examples
are described hereinafter. Note that "cured" in each of the
examples and comparative examples means that each composition has
fully cured under the respective curing conditions.
Preparation of Curing-Reactive Organopolysiloxane Composition
[0073] The curing-reactive organopolysiloxane compositions
illustrated in each of the examples and Comparative Examples 1 and
2 were prepared using the components shown in Table 1.
Adhesive Force Measurement
[0074] Each composition was applied to a PET film (manufactured by
Toray Co., Ltd., product name: Lumirror (registered trademark)
#50-T60 so that the thickness after curing was 50 .mu.m, and cured
for 2 minutes at the temperature indicated in each of the examples
and the like (120, 150, 160, or 180.degree. C.). The sample was cut
to a width of 20 mm, and the adhesive layer surface was affixed to
a PMMA plate (manufactured by Paltec, ACRYLITE L001,
50.times.120.times.2 mm) using a roller to form a test piece. The
adhesive force (measurement at a width of 20 mm converted to the
display unit N/25 mm) was measured at a tensile speed of 300 mm/min
using a 180.degree. peel test method in accordance with JIS Z 0237,
using an RTC-1210 tensile tester manufactured by Orientec Co.,
Ltd.
[0075] Similar adhesive force measurement tests were performed in
triplicate for each composition, and the average values are shown
in Table 3.
Pot Life
[0076] Each composition was left to stand for 8 hours at room
temperature (25.degree. C.), and the viscosity of the composition
after 8 hours was evaluated as "o" if the viscosity was not greater
than 1.5 times the initial value.
Thermal Aging
[0077] Each composition was applied to a release liner
(manufactured by Dow Corning Corporation, Q27785 release coating
applied to a PET film with a thickness of 50 .mu.m) so that the
thickness after curing was 100 .mu.m, and after the composition was
left to stand for 3 minutes at room temperature, the composition
was cured for 3 minutes at the temperature indicated in each of the
examples and the like (120, 150, 160, or 180.degree. C.).
Thereafter, the sample was affixed to a glass plate (manufactured
by Matsuura Glass, 76.times.52.times.1 mm, same hereafter), and the
portion protruding from the glass plate was cut off to produce a
sample for thermal aging.
[0078] The sample was subjected to thermal aging for 300 hours in
an oven at 85.degree. C. and 85% relative humidity or at
105.degree. C.
UV Irradiation
[0079] A sample affixed to a glass plate was produced with the same
method as in the case of thermal aging described above. The release
liner was then peeled off, and the adhesive layer on the glass
plate was directly irradiated with UV rays for 75 hours using an
Optical ModuleX manufactured by Ushio Electric Co., Ltd.
[0080] Note that the UV ray intensity was 3.5 mW/cm.sup.2 at 254
nm, 12 mW/cm.sup.2 at 365 nm, and 147 mW/cm.sup.2 at 405 nm, and
the temperature of the sample irradiated with UV rays at room
temperature was 35.degree. C.
(Optical Measurement: Measurement of b* Value of Each Sample)
[0081] Each sample was affixed to a glass plate with a method
similar to that of the sample produced for thermal aging described
above, and after the release liner was peeled off, the b* value of
each sample was measured using a similar glass plate as a reference
with the CIE 1976 L*a*b*D65 test method at a viewing angle of
2.degree. using a spectrophotometer (manufactured by Konica
Minolta, Model No. CM-5).
[0082] Note that the release liner was peeled off in the same
manner as described above from the sample after thermal aging to
measure the b* value.
[0083] In addition, since the release liner is already peeled off
from the sample after UV irradiation, the b* value was measured
directly.
[0084] The b* values of each of the samples measured by the method
described above (immediately after curing, after thermal aging, and
after UV irradiation) are shown in Table 2.
[0085] The materials of the curing-reactive organopolysiloxane
compositions are shown in Table 1. Note that the viscosity or
plasticity of each component was measured at room temperature using
the following methods.
Viscosity
[0086] The viscosity (mPa-s) is a value measured using a rotary
viscometer conforming to JIS K7117-1, and the kinematic viscosity
(mm.sup.2/s) is a value measured with an Ubbelohde viscometer
conforming to JIS Z8803).
Plasticity
[0087] The plasticity was expressed as a value measured in
accordance with the method prescribed in JIS K 6249 (the thickness
when a 1 kgf load was applied for 3 minutes to a 4.2 g spherical
sample at 25.degree. C. was read up to 1/100 mm, and this value was
multiplied by 100).
TABLE-US-00001 TABLE 1 Components of the curing-reactive
organopolysiloxane compositions Component Component Component A-a
Vinyl functional polydimethylsiloxane, gum-like (plasticity: 134),
vinyl content: 0.018% Component A-b Vinyl-functional
polydimethylsiloxane, gum-like (plasticity: 152), vinyl content:
0.013% Component B MQ silicone resin consisting of
(CH.sub.3).sub.3SiO.sub.1/2 units and SiO.sub.4/2 units, OH
content: 1.0%, Xylene solution (solid content: 62.6%) Component C-a
Methylhydrogenpolysiloxane capped at both terminals with
trimethylsiloxy groups, viscosity: 20 mm.sup.2/s, SiH content:
1.59% Component C-b
[(CH.sub.3).sub.2HSiO.sub.1/2].sub.0.6[SiO.sub.4/2].sub.0.4 resin,
SiH content: 0.97% Component D-a 3-Methyl-1-butyne-3-ol Component
D-b 3,5-Dimethyl-1-hexyne-3-ol Component D-c
2-Ethynyl-4-methyl-2-pentene Component E
1,3,5,7-Tetramethyl-1,3,5,7-tetravinylcyclotetra- siloxane (=cyclic
siloxane) Component F-a Platinum-based hydrosilylation reaction
catalyst containing 0.64% platinum Component F-b Platinum-based
hydrosilylation reaction catalyst containing 4.1% platinum Note)
Each % in the Table represents wt. %.
Example 1
[0088] First, 36.7 parts by weight of the vinyl functional
polydimethylsiloxane of component A-b, 100 parts by weight of the
MQ silicone resin of component B, 0.287 parts by weight of the
methylhydrogenpolysiloxane capped at both terminals by
trimethylsiloxy groups of component C-a, 0.0033 parts by weight of
the curing retarder of component D-a, 0.102 parts by weight of the
cyclic siloxane of component E, and 62.0 parts by weight of toluene
were mixed well at room temperature, and 0.0106 parts by weight of
the platinum-based hydrosilylation reaction catalyst of component
F-b was added to the mixture to form a curing-reactive
organopolysiloxane composition. The content of platinum metal
relative to the solid content was 4.24 ppm.
[0089] The composition was cured at a curing temperature of
160.degree. C. by the methods described in (Adhesive force
measurement) and (Thermal aging) above, and the evaluation results
and the like are shown in Tables 2 and 3.
Example 2
[0090] First, 36.7 parts by weight of the vinyl functional
polydimethylsiloxane of component A-b, 100 parts by weight of the
MQ silicone resin of component B, 0.466 parts by weight of the
methylhydrogenpolysiloxane capped at both terminals by
trimethylsiloxy groups of component C-b, 0.0033 parts by weight of
the curing retarder of component D-a, 0.102 parts by weight of the
cyclic siloxane of component E, and 62.0 parts by weight of toluene
were mixed well at room temperature, and 0.0106 parts by weight of
the platinum-based hydrosilylation reaction catalyst of component
F-b was added to the mixture to form a curing-reactive
organopolysiloxane composition. The content of platinum metal
relative to the solid content was 4.23 ppm.
[0091] The composition was cured at a curing temperature of
120.degree. C. by the methods described in (Adhesive force
measurement) and (Thermal aging) above, and the evaluation results
and the like are shown in Tables 2 and 3.
Example 3
[0092] First, 20.3 parts by weight of the vinyl functional
polydimethylsiloxane of component A-b, 60.3 parts by weight of the
MQ silicone resin of component B, 0.466 parts by weight of the
methylhydrogenpolysiloxane capped at both terminals by
trimethylsiloxy groups of component C-a, 0.050 parts by weight of
the curing retarder of component D-a, and 19.2 parts by weight of
toluene were mixed well at room temperature, and 0.20 parts by
weight of the platinum-based hydrosilylation reaction catalyst of
component F-a was added to the mixture to form a curing-reactive
organopolysiloxane composition. The content of platinum metal
relative to the solid content was 22 ppm.
[0093] The composition was cured at a curing temperature of
120.degree. C. by the methods described in (Adhesive force
measurement) and (Thermal aging) above, and the evaluation results
and the like are shown in Tables 2 and 3.
Example 4
[0094] The composition of Example 1 was cured at a curing
temperature of 150.degree. C. by the methods described in (Adhesive
force measurement) and (Thermal aging) above, and the evaluation
results and the like are shown in Tables 2 and 3.
Comparative Example 1
[0095] First, 21.6 parts by weight of the vinyl functional
polydimethylsiloxane of component A-a, 63.2 parts by weight of the
MQ silicone resin of component B, 0.20 parts by weight of the
methylhydrogenpolysiloxane capped at both terminals by
trimethylsiloxy groups of component C-a, 0.20 parts by weight of
the curing retarder of component D-a, and 14.9 parts by weight of
toluene were mixed well at room temperature, and 0.90 parts by
weight of the platinum-based hydrosilylation reaction catalyst of
component F-a was added to the mixture to form a curing-reactive
organopolysiloxane composition. The content of platinum metal
relative to the solid content was 100 ppm.
[0096] The composition was cured at a curing temperature of
120.degree. C. by the methods described in (Adhesive force
measurement) and (Thermal aging) above, and the evaluation results
and the like are shown in Tables 2 and 3.
Comparative Example 2
[0097] First, 21.6 parts by weight of the vinyl functional
polydimethylsiloxane of component A-a, 63.2 parts by weight of the
MQ silicone resin of component B, 0.20 parts by weight of the
methylhydrogenpolysiloxane capped at both terminals by
trimethylsiloxy groups of component C-a, 0.20 parts by weight of
the curing retarder of component D-a, and 14.9 parts by weight of
toluene were mixed well at room temperature, and 0.90 parts by
weight of the platinum-based hydrosilylation reaction catalyst of
component F-a was added to the mixture to form a curing-reactive
organopolysiloxane composition. The content of platinum metal
relative to the solid content was 100 ppm.
[0098] The composition was cured at a curing temperature of
180.degree. C. by the methods described in (Thermal aging) above,
and the evaluation results and the like are shown in Tables 2 and
3.
Comparative Example 3
[0099] A 3M 8146-4 Optically Clear Adhesive sold as a cured
adhesive film with a thickness of 100 .mu.m was used as Comparative
Example 3. An optical measurement was performed by peeling off the
release liner on the light release side, affixing the sample to the
glass plate described above, and peeling off the release liner on
the heavy release side, and the b* value was evaluated using the
same spectrophotometer.
TABLE-US-00002 TABLE 2 Example Example Example Comparative
Comparative Comparative b* value 1 2 3 Example 1 Example 2 Example
3 Initial value 0 0.01 0.03 0.10 0.26 0.03 (immediately after
curing) 85.degree. C./ -0.08 -0.07 0.03 0.28 0.30 -0.02 85%
relative humidity, 300 hours 105.degree. C., -0.01 0 0.13 0.46 0.48
0.07 300 hours UV irradiation, -0.03 -0.03 0.06 0.29 0.29 0.66 75
hours b* values at the initial stage and after thermal aging/UV
irradiation (for cured layers with a film thickness of 100
.mu.m)
TABLE-US-00003 TABLE 3 Pot life and curability (adhesive force
measurement for cured layers with a film thickness of 50 .mu.m)
Physical Exam- Exam- Exam- Exam- Comparative properties ple 1 ple 2
ple 3 ple 4 Example 1 Pot life .smallcircle. .smallcircle.
.smallcircle. .smallcircle. .smallcircle. Adhesive force 19.6 19.9
19.8 23.3 21.2 of cured layer (N/25 mm)
[0100] As shown in Table 3, each of the compositions in the
examples and the cured layers using the same have sufficient
adhesive strength equivalent to that of the silicone adhesive shown
in Comparative Example 1, and have a sufficient pot life, with no
problems such as thickening, even when stored for a long period of
time at room temperature. Further, as shown in Table 2, the cured
layers using the compositions according to these examples have
characteristics such that the b* value is low, transparency is
excellent, and there is substantially no coloration or
discoloration because the b* value of the cured layer does not
fluctuate significantly, even immediately after curing, after
thermal aging, and after UV irradiation. On the other hand, each of
the adhesive agents described in Comparative Examples 1 to 3
develops problems with discoloration or coloration in that the b*
value immediately after curing is large, or the b* value of the
cured layer fluctuates significantly after thermal aging or after
UV irradiation.
* * * * *