Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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~TRAVIO~ET-CURABL~ SILICONE COMPOSITION
FIELD OF THE INVENTION
The present invention relates to an ultraviolet-
curable polyorganosiloxane (hereinaf~er referred to as
"silicone") composition. More particularly, the present
invention relates to an ultraviolet-curable silicone
composition which can be used for arbitrarily regulating the
release properties of release papers and the like.
BACKGROUND_OF THE INVENTION
It has conventionally been well known that compositions
containing silicones as the major component are used to produce
pressure-sensitive tapes and various kinds of labels. In these
processes, the compositions are applisd on surfaces of
substrates such as various kinds of papers, synthetic films,
and fabxics, and cured to form films of the compositions,
thereby impaxting non-adhesive properties, i.e., release
properties, which prevent or reduce adhesion of tacky
substances. Such silicone compositions which impart release
properties are required to have properties such as coating
property and curability for film formation, and cured films
obtained from the compositions are required to have properties
such as release properties and the property of not adversely
affecting pressure-sensitive adhesive layers (the composition
component's property of not transferring to pressure-sensitive
adhesive layers; this property is evaluated, for example, in
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terms of percentage of subsequent adhesion for the
pressure-sensitive adhesive layers). In particular, the
release properties of cured non-adhesive films are important
for the specifications of pressure-sensitive adhesive tapes and
various labels, so that the silicone compositions are required
to give various degrees of peel strength ranging from light
release to heavy release. Pressure-sensitive tapes ox the like
are roughly classified in terms of peel strength into the
following three groups, although measured peel stxength values
vary dependin~ on the measuring methods and other conditions:
thosé having peel streng~h of 30 g/Scm or less are light-
ralease; those having peel strength more than 30 g/5cm but not
more than lO0 g/5cm are medium-release; and those having peel
strength exceeding lO0 g/5cm are heavy-release. Such regulated
peel strength are required not to change with the lapse of time
and to be maintained stably. This long-term stability of peel
strength is important when medium-to-heavy release is required.
Known silicone compositions which impart such release
properties include a composition which comprises a
polyorganosiloxane terminated by a hydroxyl group or a
hydrolyzable group and is cured by the condensation reaction of
the polyorganosiloxane with a crosslinking agent as disclosed
in, for example, J~-A-47-34447 (published 1972ill/21) (the term
"JP-A~ as used herein means an "unexamined published Japanese
patent application") and a composition which comprises a
polyorganosiloxane containing a ~il.icon-bonded alkenyL group and a
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polyor~anohydrogensiloxane containing 3 or more silicon-bonded
hydrogen atoms per molecule and is cured by the addition
reaction of the two kinds of siloxan~ polymers using a platinum
catalyst as disclosed in, for example, JP-B-52-40918(published
1977/lO/14) (the term "JP-B" as used herein means an "unexamined
Japanese paten~ publication").
However, these silicone compositions have had a
disadvantage that in the case of industrially conducting
continuous surface treatment of various substrates with the
compositions, curing reaction should be effected at
temperatures higher than 100C, generally 120C or more, for
rapid film foxmation. Because of this, applications of the
above silicone compositions have been limited to substrates
having heat resistance, and the compositions are not applicable
lS to treatment of plastic substrates for which there is an
increased desire in recent years.
On the other hand, as a technique for regulating peel
strength, it has been disclosed to impart heavy-release
properties by adding a tacky silicone resin ingredient to an
addition reaction-type silicone compo~ition which gives
light-release peel strength as disclosed in, for example,
JP-A-59~84935 (1984/05/16) and JP-A-1-215857 (1989/08/29).
Howe~er, films ~ormed from this composition are insufficient
in the lony-term stability of regulated peel strength, so that
there has been a problem that the peel strength becomes low
with the lapse of time.
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As a means to aliminat~ the disadvantage of
heat-curable silicone compositions, applications of which are
limited to substrates having heat resistance,
ultraviolet-curable silicone compositions have been developed.
S Ultraviolet-irradiating apparatuses are being most
extensively used because they are not expensive, maintenance
thereof is easy, and there is little danger to the users,
although they are one kind of radiation emitters. This method
has advantages that curing time can normally be short and that
even when the silicone compositions are applied on substrates
which are damaged by heat energy, the coatings can be cured by
ultraviolet irradiation without heating.
The ultraviolet-curable silicone compositions are
roughly divided according to cure mechanism into the following
four types:
(1) Compositions which are cured by reacting Si-Vi group (Vi
means vinyl group) and Si-H gxoup in the presence of a platinum
catalyst by means of ultraviole~ rays;
(2) Compositions in which an acrylic-functional silicone is
cured in the presence of a radical cleavage-type photocatalyst
by means of ultraviolet rays (~ee JP-A-58-213024
(1983/12/10) and JP-A-61-2g3268 (1986/12J24));
(3) Compositions which are cured by reacting Si-Vi group and
SH group in the presence of a radical cleavage-type
photocatalyst by means of ultraviolet rays (see JP-A-60-84329
(1985/05/13)); and
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(4) Compositions in which an epoxy-functional ~ilicone is
cured in the presence of a cation-generating catalyst by means
of ultra-violet rays (see JP-A-56-166224 tl981/12/21), JP-A-
58-213024 (1983/12/10), JP-A-60-47064 (1985/03/14), JP-A-1-
297421 tl989/11/30) and JP-A-1-311103 (1989/12/15)).
Silicone compositions of type (1) above are
economically disadvantageous in that the expensive catalyst
should be used in a large quantity.
Compositions of type (2) cure quickly, but curing
]~ reaction should be conducted in an inert gas atmosphere because
the cure is inhibited by oxygen. For this reason, they are
disadvantageous in that apparatuses therefor should be
specially designed and the running cost is high due to the use
of an inert gas.
Compositions of type (3) have excellent curability with
little curing inhibition by oxygen. However, the compositions
have disadvantages that because they contain mercapto groups,
they have a strong offensive odox, which is unfavorable to the
workers, and that the compositions are so unstable that their
shelf lives are short.
Compositions of type (4) cure by means of ultraviolet
rays without suffering curing inhibition by oxygen and do not
emit an offensive odor. Thus, the compositions of this type
have exceedingly good properties.
2S In the case of the epoxy-functional silicone
compositions of type (4) above, it has been disclosed to add a
polyfunctional epoxy monomer or a mixture of such monomers in
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order to obtain various degrees of peel strength, particularly
around medium to-hea~y peel strength (JP-A-60-47064
(1985/03/14)). This technique, however, has had a problem
that when a pressure-sensitive adhesive layer is peeled from
the substrate coated with the above treating agent, peeling
from the non-adhesive surface comes to be not smooth as the
peeling speed increases, making a loud noiss lpeeling noise),
and had another problem that peel strength regulation itself
^is difficult if delicate regulation is required, so that this
technique is unsatisfactory for practical use.
SUMMARY OF THE INVENTION
The present inventors have conduc~ed intensive studies
to develop an ultraviolet-curable silicone composition which is
free from the above-described problems. As a result, it has
now been found that by adding a silicone copolymer comprising
specific constituent units to an epoxy-functional silicone
composition, peel strength can be arbitrarily regulated without
impairing ultraviolet curability, and generation of peeling
noises at the time of high-speed peeling can be prevented. The
present invention has been completed based on this finding.
Accordingly, one object of the present invention is to
provide a silicone composition which eliminates the
conventional problems described above.
Anothex object of the present invention is to provide
an ultraviolet-curable silicone composition which possesses
advantages of ultraviolet-curable epoxy-functional silicone
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compositions and has other advantages that it is also
applicable to substrates not having heat resistance, and that
peel strength can be regulated within the range of from medium
release to heavy release and the regulated peel strength is
stably maintained over a prolonged period of time.
Further object of the present invention is to provide
an ultraviolet-curable silicone composition which can form
cured films which have been regulated to have peel strengths in
the range of from medium release to heavy release and are free
from the problem of generating loud peeling noises when they
are peeled from pressure-sensitive adhesive layers at high
speeds.
The ultraviolet-curable silicone composition of the
present invention comprises
(A) 100 parts by weight of an epoxy-functional
polyorganosiloxane which comprises structural units represented
by the formula RlR2SiO, wherein Rl represents hydrogen atom or
a monovalent hydrocarbon group and R2 repxesents hydrogen atom,
a monovalent hydrocarbon group, or a monovalent
epoxy-functional organic group, and in which at least two of
all the organic groups are a monovalent epoxy-functional
organic group;
(B) from 1 to 80 parts by weight of at least one
copolymer for regulating peel strength, which is soluble in
component (A), selected from the group consisting of
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(i) a copolymer represented by a unit structure of MQ
or MAQ
(ii) a copolymer represen~ed by a unit structure of
MAT, MIA or MAIA, and
(iiî) a copolymer represented by a unit structure of
MADQ, M~Q MA~Q
wherein
M represents an R33SiOIl2 unit,
MA represents an R32R4Siol,2 unit,
D represents an R32Sio unit,
DA represents an R3R4Sio unit,
T represents an R3Sio3/2 unit,
IA represents an R4Sio3~ unit, and
Q represents an SiO2 unit,
wherein R3 is a monovalent hydrocarbon group containing
no alkenyl group and R4 is an alkenyl group; and
(C) a catalytically effective amount of an onium salt
as a photoinitiator.
DETAILED DESCRIPTION OF THE IMVENTION
The epoxy-functional polyorganosiloxane as component
(A) in the composition of the present invention is obtained by
an addition reaction (hydrosilylation) of a polymethyl-
hydrogensiloxane as a base polymer with an olefinic epoxy
monomer such as 4-vinylcyclohexene oxide, allyl glycidyl ether,
or 7-epoxy-1-octene, using a catalyst such as a platinum
compound. Alternatively, the polyorganosiloxane (A) may be
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obtained by partially crosslinking polymethylhydrogensiloxane
as a base polymer with a polyorganosiloxane having at least two
alkenyl groups per molecule, and then subjecting the partially
crosslinked polysiloxane to addition reaction with the above-
descxibed olefinic epoxy monomer.
For the purpose of causing the silicone composition to
cure at a practical rate upon exposure to ultraviolet
radiation, at least two per molecule of all the organic groups
in component (A) should be an epoxy-functional organic group,
and it is preferred that from 1 to 20 mol% of all the organic
groups be an epoxy-functional organic group. If the number of
epoxy-functional organic groups per molecule is below 2, the
final composition cures too slowly and cannot give a cured film
having the desired properties because the cure does not proceed
to a sufficient degree. On the other hand, if the content of
epoxy-functional organic groups exceeds 20 mol%, smooth-release
properties cannot be obtained and peeling noises tend to
generate.
From the standpoint of easy availability of raw
materials, it is preferred that the organic groups other than
epoxy-functional organic groups in component (A) be methyl or
phenyl.
The copolymer for regulating peel strength, component
(B) f which is soluble in component (A) is the most
characteristic ingredient of the silicone composition of the
present invention. This copolymer serves to impart
medium-to-heavy peel strength which is stable oJer a prolonged
period of time to cured films to be obtained from the
composition of the present invention. Such copolymer for
regulating peel strength is at least one member selected from
the following silicone resins:
(i) a copolymer represented by a unit structure of MQ
or MAQ,
(ii) a copolymer represented by a unit structure of
MAT, MTA or MATA, and
(iii) a copolymer represented by a unit structure of
MADQ MDAQ or MA~Q
wherein
M represents an R33SiOl/2 unit,
MA represents an R32R4Siol/2 unit,
D represents an R32Sio unit,
DA represents an R3R4Sio unit,
T represents an R3SiO3t2 unit,
TA represents an R4Sio3~2 unit, and
Q represents an SiO2 unit,
wherein R3 is a monovalent hydrocarbon group containing
no alkenyl group and R4 is an alkenyl group.
In component (B), the content of each structural unit
is-not particularly limited. However, from the standpoint of
the relationship between the amount of component (B) added and
peel strength regulation, it is practically preferred that the
content of M or MA units be from 25 to 70 mol~. If the content
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of M or MA units is below 25 mol%, the compatibility of
component (B) with componen~ (A) is reduced, and cured films of
the resulting composition have too high peel strength, so that
peel strength regulation becomes difficult. If the M or
unit content exceeds 70 mol~, the peel strength-regulating
effect is decreased and, hence, component (B) is required to be
added in an increased amount, which may result in poor
film-forming properties of the resulting composition and
impaired properties of cured films.
The D or DA structural unit is not essential in
component (B). However, in the case where the copolymer
contains such units, the content thereof preferably is 50 mol~
or less. If the D or ~ unit content exceeds 50 mol%, the peel
strength-regulating effect is decreased.
It is preferred that the copolymer for regulating peel
strength contains an alkenyl group represented by R4 because
the R4 group brings about excellent peel strength-regulating
effect. Examples of the alkenyl group include vinyl and allyl
groups, with vinyl group being preferred from the standpoints
of easy availability of raw materials and cost.
In component (B), the monovalent hydrocarbon group R3
containing no alkenyl group preferably is methyl or phenyl from
the standpoint of easy availability of raw materials.
The amount of component (B) added to component (A) is
from 1 to 80 parts by weight, preferably from 5 to 70 parts by
weight, per 100 parts by weight of component (A~. If the
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amount of component (B) added is below 1 part by weight, the
effect of increasing peel strength becomes insufficient. If
- the amount thereof exceeds 80 parts by weight, release
properties are impaired disadvantageously.
The photoinitiator ~C) is not particularly limited as
long as it is an onium salt which is compatible with components
(A) and (B) and is capable of cleaving an epoxy ring with
light.
A preferred photoinitiator used in the present
invention is an onium salt represented by the formula R52I+MXn-,
R53S~MX~-, R53Se~MX~~, R54P+MX~-, or R54N~MXn- (wherein R5 which may be
the same or different each is a Cl-C30 organic group selected
from the group consisting of (1) a C6-C20 aromatic hydrocarbon
group, (2) a C6-C20 aromatic hydrocarbon group which has been
substituted with from 1 to 4 monovalent organic groups or atoms
selected from a Cl-C8 alkoxyl group, a Cl-C8 alkyl group,
nitrogen atom, chlorine atom, bromine atom, cyano group,
carbo~yl group, and mercapto group, and (3) an aromatic
hydrocarbon group selected from pyridyl group, thiophenyl
group, and pyranyl group; and MXn- is a non-basic and
non-nucleophilic anion selected from ~he group consisting of
BF4, PF6, AsF6 J SbF6-, SbC16-, HS04- ~ and Cl04- ) o The amount of
this photoinitiator added is no~-particularly limited, but is
preferably from 0.5 to 3.0 parts by weight per 100 parts by
weight of component (A) from the standpoints of curing rate and
cost.
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Non-adhesive films obtained by curing the composition
of the present invention can he regulated to have a~bitrary
peel strength without impairing the ultraviolet curability of
the composition, and the peel strength of the cured films
changes only little with the lapse of time. In the case where
the composition of the present inven~ion is used to -orm the
release coating in a pressure-sensitive tape, the release
coating does not impair the tack strength of the
pressure-sensitive adhesive layer peeled from the release
coating and does not otherwise adversely affect the adhesive
layer. Even in the case where the peel strength is re~ulated
to obtain heavy release, peeling of the pressure-sPnsitive
adhesive layer from the release coating can be conducted
smoothly without generating peeling noises. Furthermore, since
the composition of the present invention can be cured easily
and rapidly at a low temperature only by means of ultraviolet
irradiation without the necessity of heating, it not only is
applicable even to plastic materials having low heat
resistance, but also can be applied to commonly used substrates
such as paper to produce, at high speed, various kinds of tapes
and labels having different peel strengths. Therefore, the
composition of the present invention is useful to attain
significantly improved production efficiencies of these
processes.
The present invention will be explained below in more
detail by reference to Examples and Comparative Examples, but
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the Examples should not be construed as limiting the scope of
the invention. In these examples, all parts are by weight.
[Sample Preparation]
Each of the compositions obtained in Examples and
Comparative E~amples was coated on a polyethylene-laminated
paper (75 g/m2) at a coating thickness of 1.3 g/m~. Using an
irradiation apparatus comprising a conveyor for conveying
coated paper and a single, high-pressure mercury lamp (80 W/cm)
installed at a height of 10 cm from the conveyor surface, the
coating w~s curéd while the coated paper was conveyed by the
conveyor a~ à speed of 5 m/min. After curinq, the resulting
coated papers were aged at room ~emperature for 1 to 28 days
and then subjected to the following tests.
~Peel Strength Measurement]
To the sùrface of the cured coating on an ayed coated
paper, No. 502 Tape (trade name, manufactured by Nitto Denko
Corporation, Japan) was applied by pressing the tape by moving
a 2-kg rubber roller forward and backward once on the tape.
This sample was then aged at 100C for 1 hour. After the aged
sample was cooled to room temperature, the tape was peeled off
in the 180 direction at a speed of 0.3 m/min to measure the
peel streng~h.
~Measurement of Percentage of Subsequent Adhesion]
To the surface of the cured coating on a coated paper
aged for 1 day, Nitto*31B Tape ttrade name, manufactured by
Nitto Denko Corporation; width 2.5 cm~ was applied. The
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applied tape was allowed to stand at 70C for 20 hours und~r a
load of 20 g/cm2. The resulting tape was peeled off, and then
applied to a stainless-steel plate (JIS C2107) by pressing the
tape with a 2-kg rubber roller. This sample was aged at 25C
for 3 hours, and the tape was then peeled off in the 180
direction to measure the peel strength (f). On the other hand,
a blank sample was prepared using Nitto 31B Tape applied to a
polytetrafluoroethylene film, and its peel strength (f0) was
measured in the same manner as the above.
Percentage of subsequent adhesion (%) was calculated
using the following equation.
Percentage of Subsequent Adhesion (~) = f/fO x 100
tEvaluation of Peeling State and Peeling Noise]
Peeling state and peeling noise were examined in the
peel strength measurement described above, and were evaluated
based on the following criteria.
(Peeling State)
O ......... Peel strength is constant and peeling chart is
stable.
x ......... Peel strength is not constant and peeling
chart is unstable.
(Peeling Noise)
O ......... Tape was peeled off smoothly without
generating peeling noise.
~ ......... Tape was peeled off while slightly generating
a peeling noise.
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x ...... Peeling of the tape was not smooth, generating
a loud peeling noise.
[Synthesis of Epoxy-Modified Silicone Oil (I)]
With 1,000 parts of a polymethylhydrogensiloxane both
ends of which had been blocked with a trimethylsilyl group,
having a viscosity of 16 cSt at 25C and a hydrogen content of
0.16% by weight was mixed 200 parts of a polydimethylsiloxane
both ends of which had been blocked with a dimethylvinyl group,
having a viscosity of 400 cSt at 25C. To the resulting
mixture was added an isopropyl alcohol (IPA) solution of
chloroplatinic acid in an amount of 15 ppm in terms of the
amount of platinum. Reaction was then conducted at 50C for 1
hour. To the resulting reaction mixture, 250 parts of
4-vinylcyclohexene oxide was added dropwise over a period of 2
hours. Although this addition was accompanied with heat
generation, the reaction mixture was kept at a temperature
between 50 and 60C to conduct reaction for 4 hours.
Thereafter, topping was effected at 130C for 2 hours under a
pressure of 10 mmHg to remove unreacted ingredients and
low-boiling fractions. Thus, epoxy-modified silicone oil (I)
was obtained which had a viscosity as measured at 25C of 250
cSt.
~Synthesis of Epoxy-Modified Silicone Oil (II)]
To 1,000 parts of a polymethylhydrogensiloxane both
ends of which had been blocked with a dimethylhydrosilyl group,
having a viscosity of 23 cSt at 25C and a hydrogen content of
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0.10% by weight was added an IPA solutios of chloroplatinic
acid in an amount of 15 ppm in terms of the ~mount of platinum.
This mixture was heated to 50~C. To the mix~ure was then added
dropwise 200 parts of 4-vinylcyclohexene ox-~e over a period of
2 hours. Thereafter, reaction was conducted at 50 to 60C for
4 hours, and topping was then effected at 130C for 2 hours
under a pressure of 10 mmHg to remove unreacted ingredients and
low-boiling fractions. Thus, epoxy-modified silicone oil (II)
was obtained which had a viscosity as measured at 25C of 300
cSt.
[Synthesis of Epoxy-Modified Silicone Oil ~III)]
To 50 parts of 4-vinylcyclohexene oxide was added 1,000
parts of toluene. To the mixture was further added an IPA
solution of chloroplatinic acid in an amoun~ of:15 ppm in terms
of the amount of platinum. While the temperature of this
mixture was kept between 100 and 115C, 1,000 parts of a
polymethylhydrogensiloxane both ends of which had been blocked
with a tri~.e~hylsilyl group, having a viscosity of 18 cSt at
25C and a hydrogen content of 0.32% by weight was added
dropwise to the mixture over a period of 2 hours. Thereafter,
reaction wzs conducted at 120C for 4 hou~s, and topping was
then effected at 130C for 3 hours under a pressure of 10 mmHg
to remove unreacted ingredients and low-boiling fractions.
Thus, epoxy-modified silicone oil (III) was obtained which had
a viscosity as measured at 25C of 280 cSt.
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EXAMPLE 1
30 Parts of a 60 wt% toluene solution of a silicone
resin represented by the average composition formula
~(CH3)3SiOl/2]6[(CH3)2sio~2[sio2]8 was mixed with 100 parts of
S epoxy-modified silicone oil (I). Topping was then conducted at
120C for 2 hours under a pressure of 10 mmHg. After the
residual mixture was cooled to 25C, 2 parts of
bis(dodecylphenyl)iodonium hexafluoroantimonate was added
thereto, and the result~ng mixture was stirred to give a
coating fluid.
COMPA~ATIVE EXAMPLE 1
To 100 parts of epoxy-modified silicone oil (I) was
added 2 parts of bis(dodecylphenyl)iodonium
hexafluoroantimonate. This mixture was stirred to give a
coating fluid.
COMPA~ATIVE EXAMPLE 2
A coating fluid was prepared in the same manner as in
Example 1 except that the amount of the 60 wt% toluene solution
of silicone resin was changed to 1 part.
COMPARATIVE EXAMPLE 3
A coating fluid was prepared in the same manner as in
Example 1 except that the amount of the 60 wt~ toluene solution
of silicone resin was changed to 150 parts.
The coating fluids obtained in Example 1 and
Comparative Examples 1 to 3 were examined for peel strength,
percentage of subsequent adhesion, peeling state, and peeling
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noise according to the evaluation methods as described
hereinabove. The results obtained are shown in Table 1.
Table 1
5Peel Stren~th (~/5cm) Percen-
After After After After tage of
1 7 14 28 Subsequent Peeling Peeling
dav days daYs days Adhesion State_ Noise
(~)
Comparative 30 32 31 32 97 0 0
Example l
Example 1 62 59 54 63 99 0 0
Comparative 31 30 3~ 30 97 0 0
Example 2
Comparative not not not not 97
Example 3 peel- peel- peel- peel-
ed ed ed ed
EXAMPLE 2
lO Parts of a 60 wt% toluene solution of a silicone
resin represented by the average composition formula
[(CH3)3SiOl/2]10~SiO2]8 was mixed with 100 parts of epoxy-modified
silicone oil (I). Topping was then conducted at 120C for 2
hours under a pressure of 10 mmHg. After the residual mixture
was cooled to 25C, 3 parts of bis(dodecylphenyl)iodonium
hexafluoroantimonate was added thereto and the resulting
mixture was stirred to give a coating fluid.
EXAMPLE 3
A coating fluid was prepared in the same manner as in
Example 2 except that the amount of the 60 wt% toluene solution
o~ silicone resin was changed to 30 parts.
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EXAMPLE 4
A coating fluid was prepared in the same manner as in
Example 2 except that the amount of the 60 wt% toluene solution
of silicone resin was changed to 60 parts.
EXAMPLE 5
A coating fluid was prepared in the same manner as in Example
2 except that the amount of the 60 wt% toluene solution of
silicone resin was changed to 90 parts.
The coating fluids ob~ained in Examples 2 to 5 were
examined for peel strength, percentage of subse~uent adhesion,
peeling state, and peeling noise accordinq to the evaluation
methods as described hereinabove. The results obtained are
shown in Table 2.
Table 2
Peel Strenqth (q/Scm~ Percen-
After After After After tage of
1 7 14 28 Subsequent Peeling Peeling
day day~ days _daYs Adhesion State Noise
(%)
Example 2 40 43 44 42 99 0 0
Example 3 73 71 72 70 100 0 0
Example 4 112 115 116 116 100 0 0
Example 5 161 163 165 162 100 0 0
EXAMPLE 6
50 Parts of a 60 wt% xylene solution o a silicone
resin represented by the average composition formula
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2 ~ 2 ~
~(CH2=CH)(CH3)2SiOll2]4[CH3SiO3/2]l0 was mixed with 100 parts of
epoxy-modified silicone oil (II). Topping was then conducted
at 120C for 2 hours under a pressure of 10 mmHg. After the
residual mixture was cooled to 25C, 2 parts o
bis(dodecylphenyl)iodonium hexafluoroant.imonate was added
thereto and the resulting mixture was stirred to give a coating
fluid.
COMPAR~TIVE EXAMPI.E 4
To 100 parts of epoxy-modified silicone oil (II) was
added 2 parts of bis(dodecylphenyl)iodonium
hexafluoroantimonate. This mixture was stirred to give a
coating fluid.
The coating fluids obtained in Example 6 and
Comparative Example 4 were examined for peel strength,
percentage of subsequent adhesion, peeling state, and peeling
noise according to the evaluation me~hods as described
hereinabove. The results obtained are shown in Table 3.
Table 3
~ Percen-
After After After After tage of
1 7 14 28 Subseguent Peeling Peeling
_~y_ _~y~ days days Adhesion State Noise
Example 6 77 74 76 75 99 0 0
Comparative 43 42 45 43 98 0
Example 4
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COMPARATIVE EXAMP~E 5
To 100 parts of epoxy-modified silicone oil (III) was
added 2 parts of bis(dodecylphenyl)iodonium
hexafluoroantimonate. This mixture was stirred to give a
coating fluid.
The coatin~ fluid prepared above was examined according
to the evaluation methods as described hereinabove. The
results obtained are as follows. The peel strength was 145
g/5cm after 1 day, 139 g/5cm after 7 days, 152 g/5cm after 14
days, and 141 gJScm after 28 days; the percentage of subsequent
adhesion was 100~; and the peeling state ~as x because peeling
of the tape was not smooth and a loud peeling noise was
generated.
EXAMPLE 7
lS 117 Parts of a 60 wt% toluene solution of a silicone
resin represented by the average composition formula
[(CH3)3SiO~t2] 6[ t CH3)(CH2=CH)SiO]~2~SiO2]2 was mixed with 100 parts
of epoxy-modified silicone oil ~ opping was then conducted
at 120C for 2 hours under a pressure of 10 mmHg. After the
residual mixture was cooled to 25C, 2 parts of
bistdodecyIphenyl)iodonium hexafluoroantimonate was added
thereto and the resulting mixture was stirred to give a coating
fluid. - -
EXAMPLE 8
30 Parts of a 60 wt% toluene solution of a silicone
resin represented by the average composition formula
, I ; , i, . ~
2~
~(CH3)3SiOl/2],0[SiO2]8 was mixed with 100 parts of epoxy-modified
silicone oil (III). Topping was then conducted at 120C for 2
hours under a pressure of 10 mmHg. After the residual mixture
was cooled to 25C, 3 parts of bis(dodecylphenyl)iodonium
r hexafluoroantimonate was added thereto and the resulting
mixture was s~irred to give a coating fluid.
coMpARArrIvE EXAMPLE 6
A coating fluid was prepared in the same manner as in
Example 7 except that the amount of the 60 wt~ toluene solution
of silicone resin was changed to 1 part.
COMPARATIVE EXAMPLE 7
A coating fluid was prepared in the same manner as in
Example 7 except that the amount of the 60 wt~ toluene solution
of silicone resin was changed to 150 parts.
1~ COMPARATIVE EXAMPLE 8
2 Parts of limonene dioxide was mixed with 100 parts of
epoxy-modified silicone oil (II). To the mixture was then
added 2 parts of bis(dodecylphenyl)iodonium
hexafluoroantimonate. The resulting mixture was stirred to
2~ give a coating fluid.
COMPARATIVE EXAMPLE 9
4 Parts of limonene dioxide was mixed with 100 parts of
epoxy-modified silicone oil (III). To the mixture was then
added 2 parts of bis(dodecylphenyl)iodonium
2~ hexafluoroantimonate. The resulting mixture was stirred to
give a coating fluid.
- 23 -
. ,
COMPARATIVE EXAMPLE 10
To 100 parts of a silicone oil represented by the
a v e r a g e c o m p o s i t i o n f o r m u l a
~(CH2=CH)(CH3 ) 2sil/2 ] 2 [ ( CH3 ) 2SiO ] 245 ~(CH2=CH)(CH3)SiO]3wasadded30
parts of a 60 wt% toluene solu~ion of a silicone resin
represented by the average composition formula
~(CH3)3SiOl/2]l~[SiO2]8. This mixture was stirred until it became
uniform, and topping was then conducted at 120C for 2 hours
under a pressure of 10 mmHg. After the residual mixture was
cooled to 25C, 3 parts of [(CH3)3Siol~2]~[(CH3)HSiO]38 and 2 parts
of a chloroplatinic acid isopropyl alcohol solution (having a
platinum content of 1.0 wt~ in terms of the amount of platinum
atom) were added thereto, and the resulting mixture was stirred
to give a coating fluid. This coating fluid was coated on the
same polyethylene-laminated paper as described in [Sample
Preparation] given hereinabove at the same coating thickness,
and the coating was heat-cured in an oven at 140C for 30
seconds. This sample was subjected to the same e~aluation
tests as described above.
The coating fluids obtained in Examples 7 and 8 and
Comparative Examples 6 to 10 were examined for peel strength,
percentage of subsequent adhesion, peeling state, and peeling
noise according to the evaluation methods as described
hereinabove. The results obtained are shown in Table 4.
- 24 -
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-- 25 --
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.:
While the invention has been described in detail and
with reference to specific embodiments thereof, it will be
apparent to one skilled in the art that various changes and
modifications can be made therein without departing fro~ the
spirit and scope thereof.
;~
,
