U.S. patent application number 09/155075 was filed with the patent office on 2001-07-19 for photopolymerizable composition, pressure-sensitive flame-retardant adhesive, and adhesive sheets.
Invention is credited to MUTA, SHIGEKI, OURA, MASAHIRO, YOSHIKAWA, TAKAO.
Application Number | 20010008689 09/155075 |
Document ID | / |
Family ID | 13773351 |
Filed Date | 2001-07-19 |
United States Patent
Application |
20010008689 |
Kind Code |
A1 |
MUTA, SHIGEKI ; et
al. |
July 19, 2001 |
PHOTOPOLYMERIZABLE COMPOSITION, PRESSURE-SENSITIVE FLAME-RETARDANT
ADHESIVE, AND ADHESIVE SHEETS
Abstract
Adhesive sheets using an acrylic pressure-sensitive
flame-retardant adhesive having excellent properties such as
adhesive force and holding power at high temperature and also
having a self fire-extinguishing property which instantaneously
extinguishes fire, i.e., a flame-retardance, are provided. A
photopolymerizable composition comprising (a) 100 parts by weight
of a monomer (or the oligomer thereof) comprising 70 to 100% by
weight of a (meth)acrylic acid alkyl ester having on the average a
carbon number of 2 to 14 in the alkyl group and 30 to 0% by weight
of a monoethylenically unsaturated monomer copolymerizable with the
ester, (b) 0.02 to 5 parts by weight of a polyfunctional
(meth)acrylate as a crosslinking agent, (c) 0.01 to 5 parts by
weight of a photopolymerization initiator, and (d) 10 to 180 parts
by weight of a flame retardant having a melting point of at least
60.degree. C. is prepared, a pressure-sensitive flame-retardant
adhesive is prepared from the photopolymerized product of the
composition, and the adhesive is formed on one or both surfaces of
a substrate.
Inventors: |
MUTA, SHIGEKI; (OSAKA,
JP) ; YOSHIKAWA, TAKAO; (OSAKA, JP) ; OURA,
MASAHIRO; (OSAKA, JP) |
Correspondence
Address: |
SUGHRUE MION ZINN MACPEAK & SEAS
2100 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20037
|
Family ID: |
13773351 |
Appl. No.: |
09/155075 |
Filed: |
September 21, 1998 |
PCT Filed: |
March 17, 1997 |
PCT NO: |
PCT/JP97/00846 |
Current U.S.
Class: |
428/355AC ;
428/345; 428/920; 428/921; 522/182; 525/163; 525/479 |
Current CPC
Class: |
Y10T 428/2891 20150115;
C09J 4/00 20130101; C08F 220/1809 20200201; Y10S 428/921 20130101;
Y10S 428/92 20130101; Y10T 428/2809 20150115; C09J 4/00 20130101;
C08F 220/10 20130101; C09J 4/00 20130101; C08F 220/1809
20200201 |
Class at
Publication: |
428/355.0AC ;
428/345; 428/920; 428/921; 522/182; 525/163; 525/479 |
International
Class: |
B32B 007/12; B32B
015/04; B27N 009/00; C08K 005/07 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 4, 1996 |
JP |
HEI. 8-82393 |
Claims
1. A photopolymerizable composition comprising following
compositions (a) to (d); (a) 100 parts by weight of a monomer (or
the oligomer thereof) comprising 70 to 100% by weight a
(meth)acrylic acid alkyl ester having on the average a carbon
number of 2 to 14 in the alkyl group, and 30 to 0% by weight of a
monoethylenically unsaturated monomer copolymerizable with the
(meth)acrylic acid alkyl ester; (b) 0.02 to 5 parts by weight of a
polyfunctional (meth)acrylate as a crosslinking agent; (c) 0.01 to
5 parts by weight of a polymerization initiator; and (d) 10 to 180
parts of a flame retardant having a melting point of at least
60.degree. C.
2. The photopolymerizable composition as claimed in claim 1,
wherein the flame retardant of the component (d) is a bromine-based
flame retardant.
3. A pressure-sensitive flame-retardant adhesive comprising a
photopolymerized product of the photopolymerizable composition as
claimed in claim 1 or 2.
4. The pressure-sensitive flame-retardant adhesive as claimed in
claim 3, wherein the adhesive has a solvent-insoluble content of at
least 50% by weight.
5. Adhesive sheets comprising a substrate having formed on one
surface or both surfaces thereof a layer of the pressure-sensitive
flame-retardant adhesive as claimed in claim 3 or 4.
6. The adhesive sheets as claimed in claim 5, wherein the substrate
is a heat-resistant substrate.
Description
TECHNICAL FIELD
[0001] The present invention relates to a pressure-sensitive
flame-retardant adhesive required to have a sufficient adhesive
force and also a self fire-extinguishing property for
instantaneously extinguishing fire in the fields of fixation of
electronic parts, building materials, vehicles, aircraft, ships,
etc.; adhesive sheets formed by forming the pressure-sensitive
flame-retardant adhesive into, for example, a sheet form or a tape
form; and a photopolymerizable composition for obtaining the
pressure-sensitive flame-retardant adhesive.
BACKGROUND ART
[0002] An acrylic pressure-sensitive adhesive has generally been
prepared by solution-polymerizing monomers mainly comprising a
(meth)acrylic acid alkyl ester. However, from the restrictions on
safety of organic solvents and environmental health, a method of
preparing the pressure-sensitive adhesive by emulsion-polymerizing
or photopolymerizing the above-described monomers is recently
widely used.
[0003] Such a pressure-sensitive adhesive is usually that an
acrylic adhesive polymer is crosslinked with a crosslinking agent
to increase a cohesive force at high temperature, thereby imparting
an excellent heat resistance. However, since many of the adhesive
components are constituted of combustible materials, there has been
a difficulty that the pressure-sensitive adhesive cannot be used in
fields of application requiring a flame-retardance together with a
heat resistance.
[0004] To overcome this difficulty, JP-A-1-223187 (the term "JP-A"
as used herein means an "unexamined published Japanese patent
application"), for example, discloses a pressure-sensitive
flame-retardant adhesive obtained by adding a flame-retardant or a
flame-retardant assistant, such as a brominated material,
chlorinated paraffin, aluminum hydroxide, antimony trioxide, etc.,
to a adhesive base polymer such as an acrylic polymer, a synthetic
rubber, a natural rubber, etc.
[0005] However, it is necessary to add a large amount of a
flame-retardant in order to exhibit a sufficient flame is retardant
effect by such a conventional pressure-sensitive flame-retardant
adhesive. In this case, there is a problem that the heat resistance
of the pressure-sensitive adhesive is decreased. Further, if the
degree of crosslinking of the base polymer, such as a rubber, is
increased in order to improve the heat resistance, the adhesive
property thereof is decreased, so that it is necessary to add a
large amount of a tackifier. In this case, there is a problem that
holding power of the adhesive at high temperature is decreased in
addition to increase of the cost.
[0006] In view of these circumstances, an object of the present
invention is to provide an acrylic pressure-sensitive
flame-retardant adhesive which has excellent adhesive performances
such as adhesive force or holding at high temperature, and also has
a self fire-extinguishing property for instantaneously
extinguishing fire, that is, a flame-retardance; adhesive sheets
obtained by forming the pressure-sensitive flame-retardant adhesive
in, for example, a sheet form or a tape form; and a
photopolymerizable composition for obtaining the above-described
pressure-sensitive flame-retardant adhesive.
DISCLOSURE OF THE INVENTION
[0007] As a result of various investigations to attain the
above-described object, the present inventors have found that if a
photopolymerizable composition comprising a (meth)acrylic acid
alkyl ester as a main component and a specific crosslinking agent
added thereto together with a photopolymerization initiator, and a
specific flame-retardant further compounded therewith is
polymerized and cured by irradiation with ultraviolet rays, a
pressure-sensitive flame-retardant adhesive having excellent
adhesive performances such as adhesive force and holding power at
high temperature and also a self fire-extinguishing property for
instantaneously extinguishing fire, that is, a flame-retardant
property, and the adhesive sheets thereof are obtained, and have
accomplished the present invention.
[0008] That is, the present invention relates to a
photopolymerizable composition comprising following components (a)
to (d);
[0009] (a) 100 parts by weight of monomer(s) (or an oligomer
thereof) comprising 70 to 100% by weight of a (meth)acrylic acid
alkyl ester having on the average a carbon number of 2 to 14 in the
alkyl group, and 30 to 0% by weight of a monoethylenically
unsaturated monomer,
[0010] (b) 0.02 to 5 parts by weight of a polyfunctional
(meth)acrylate as a crosslinking agent,
[0011] (c) 0.01 to 5 parts by weight of a photopolymerization
initiator, and
[0012] (d) 10 to 180 parts by weight of a flame-retardant having a
melting point of at least 60.degree. C.; a pressure-sensitive
frame-retardant adhesive comprising the photopolymerization product
of this composition; and adhesive sheets having the layer of the
pressure-sensitive flame-retardant adhesive on one surface or both
surfaces of a substrate.
[0013] In the monomer of the component a) used in the present
invention, the (meth)acrylic acid alkyl ester having on the average
a carbon number of 2 to 14 in the alkyl group includes ethyl
(meth)acrylate, butyl (meth)acrylate, isoamyl (meth)acrylate,
n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, iso-octyl
(meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate,
dodecyl (meth)acrylate, and the like. Those can be used alone or as
a mixture of two or more kinds of them.
[0014] If necessary, together with the (meth)acrylic acid alkyl
ester, a monoethylenically unsaturated monomer copolymerizable with
the (meth)acrylic acid alkyl ester is used to improve adhesive
property, cohesive force, heat resistance, etc. Such a
monoethylenically unsaturated monomer includes acrylic acid,
itaconic acid, sulfopropyl acrylate, hydroxyalkyl acrylate,
cyanoalkyl acrylate, acrylamide, substituted acrylamide,
vinylcaprolactam, acrylonitrile, 2-methoxyethyl acrylate, glycyl
acrylate, vinyl acetate, etc., and according to the purpose, those
are used alone or as a mixture of two or more kinds.
[0015] In the monomer of the component a), the use proportion of
the (meth)acrylic acid alkyl ester and the monoethylenically
unsaturated monomer copolymerizable therewith is that the former is
from 70 to 100% by weight, and preferably from 85 to 95% by weight,
and the latter is from 30 to 0% by weight, and preferably from 15
to 5% by weight. By using such a use proportion, the adhesive
property, the cohesive force, etc., can be balanced well.
[0016] The polyfunctional (meth)acrylate as the crosslinking agent
which is the component b) used in the present invention functions
to increase shear strength of the adhesive. Examples thereof
include trimethylolpropane tri(meth)acrylate, pentaerythritol
tetra(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate,
1,6-hexanediol di(meth)acrylate, etc.
[0017] The amount of this polyfunctional (meth)acrylate used is
from 0.02 to 5 parts by weight, and preferably from 0.1 to 3 parts
by weight, per 100 parts by weight of the monomer as the component
(a). Within this range, where a bifunctional (meth)acrylate is
used, the amount thereof can be increased, and where a
trifunctional or more (meth)acrylate is used, the amount thereof
can be decreased. However, when the amount is less than 0.02 part
by weight, the degree of crosslinking after the photopolymerization
cannot sufficiently be increased and when the amount is larger than
5 parts by weight, there is the possibility of lowering the
adhesive force, etc., which are either undesirable.
[0018] The photopolymerization initiator as the component (c) used
in the present invention includes benzoin ethers such as benzoin
methyl ether, benzoin isopropyl ether, etc.; substituted benzoin
ethers such as anizoin methyl ether, etc.; substituted
acetophenones such as 2,2-diethoxyacetophenone,
2,2-dimethoxy-2-phenoneacetophenone, etc.; substituted a-ketols
such as 2-methyl-2-hydroxypropiophenone, etc.; aromatic sulfonyl
chlorides such as 2-naphthalenesulfonyl chloride, etc.: photoactive
oximes such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl-
)oxime, etc.
[0019] The photopolymerization initiator is used in an amount of
from 0.01 to 5 parts by weight, and preferably from 0.05 to 1 part
by weight, per 100 parts by weight of the monomer as the component
(a). If the amount thereof is less than 0.01 part by weight, the
monomer tends to remain largely, while if the amount is more than 5
parts by weight, the molecular weight of the polymer is decreased
and the cohesive force of the adhesive tends to decrease.
[0020] The flame retardant as the component (d) used in the present
invention has a melting point of at least 60.degree. C., and
preferably at least 80.degree. C. A bromine-based flame retardant
is particularly preferred. If a flame retardant having a melting
point of lower than 60.degree. C. is used, holding characteristics
of the photopolymerizable composition at high temperature are
decreased. Also, a chlorine-based flame retardant is undesirable
because the composition generates a gas such as hydrogen chloride,
etc., at high temperature, causing the possibility of corrosion of
electronic parts.
[0021] Examples of the bromine-based flame retardant having a
melting point of at least 60.degree. C. include propylene-modified
tetrabromobisphenol A, a carbonyl-modified tetrabromobisphenol A
oligomer, decabromodiphenyl ether, hexabromobenzene,
pentabromotoluene, hexabromocyclododecane, etc.
[0022] The flame retardant is used in an amount of from 10 to 180
parts by weight, preferably from 15 to 150 parts by weight, and
more preferably from 20 to 100 parts by weight, per 100 parts of
the monomer as the component a). If the amount of the flame
retardant is less than 10 parts by weight, the flame retardance is
decreased, and if the amount thereof is more than 180 parts by
weight, the adhesive properties are decreased. In addition,
conventional flame retardant assistants such as antimony trioxide,
etc., may be used together with the above-described flame
retardant.
[0023] The photopolymerizable composition of the present invention
comprises the above-described components (a) to (d) as essential
components. For preparing the photopolymerizable composition, the
monomer as the component (a) is mixed with the photopolymerization
initiator as the component (c) and the premix is partially
polymerized to form a coatable syrup form having a viscosity of
from about 50 to 5,000 centipoise. Further, the above-described
premix of the monomer and the photopolymerization initiator may be
mixed with a thixotropic agent such as fumed silica to form a
coatable syrup form.
[0024] The syrup form mixture thus obtained is then mixed with the
polyfunctional (meth)acrylate as the crosslinking agent of the
component (b), the flame retardant having a melting point of at
least 60.degree. C. as the component (d), and, if necessary, an
additional photopolymerization initiator to prepare a
photopolymerizable composition. This composition can further
contain, if necessary, conventional additives such as a filler, an
antioxidant, a tackifying resin, etc., in the range of not
inhibiting the photopolymerization by irradiation with ultraviolet
rays.
[0025] In the present invention, the photopolymerizable composition
thus prepared is irradiated with ultraviolet rays to form a
photopolymerized product. The irradiation with ultraviolet rays is
carried out in an oxygen-free atmosphere replaced with an inert gas
such as nitrogen, etc., or in the state of being intercepted from
air by covering with an ultraviolet transmittable film. The
ultraviolet rays are an electromagnetic radiation having a
wavelength range of from about 180 to 460 nm. An electromagnetic
radiation having a wavelength longer than or shorter than the
above-described range. The ultraviolet source used is a general
illuminator such as a mercury arc lamp, a carbon arc lamp, a
low-pressure mercury lamp, an intermediate-pressure or
high-pressure mercury lamp, a metal halide lamp, etc. The intensity
of the ultraviolet rays can appropriately be set up by controlling
the distance to a material to be irradiated or by controlling the
voltage. However, in view of the irradiation time (productivity),
it is desirable to use a weak light having an intensity of from 0.1
to 7 mW/cm.sup.2.
[0026] In the photopolymerized product after irradiation with
ultraviolet rays, unreacted monomers usually remain in an amount of
from about 1 to 5% by weight. The residual monomers are volatilized
in using the adhesive at high temperature to cause blister of the
adhesive surface or contamination with a gas, thereby causing
decrease of the cohesive force. Therefore, it is generally
desirable to remove the residual monomers by heat-drying after the
irradiation with ultraviolet rays. The heat-drying is usually
carried out using a drying furnace, but it is particularly
preferable to carry out the heat-drying using a hot
blast-circulating drying furnace having a far infrared heater. The
reason for this is that drying can be conducted with good
efficiency in a short period of time by heating from the inside
with the far infrared heater and by the diffusion from the surface
due to the circulating hot blast. The heat-drying treatment is
generally conducted at a temperature of from about 100 to
150.degree. C. for several tens of second to several minutes
although varying depending on the capacity of the drying
furnace.
[0027] The photopolymerized product thus obtained has a
sufficiently high molecular weight and also has a high degree of
crosslinking such that the inside of the product is crosslinked
with the crosslinking agent as the component (b) and the
solvent-insoluble content is at least 50% by weight, and preferably
from 70 to 95% by weight.
[0028] The present invention makes such a photopolymerized product
into the pressure-sensitive flame-retardant adhesive. The adhesive
has excellent adhesive force and holding power, in particular, has
excellent holding power at high temperature and good heat
resistance, and also has a high self fire-extinguishing property,
that is, high flame retardance, due to the above-described
molecular weight and degree of crosslinking.
[0029] The adhesive sheets of the present invention are prepared by
forming such a pressure-sensitive flame-retardant adhesive having
excellent heat resistance on one surface or both surfaces of a
substrate usually having a thickness of about 25 to 125 .mu.m such
that the thickness of one layer of the adhesive is usually about 10
to 150 .mu.m, thereby forming into a tape form or a sheet form.
[0030] The substrate used is a porous material such as a non-woven
fabric or a paper, and various kinds of plastics. In particular,
for a heat-resistant use, heat-resistant films such as a polyamide
film, a polyester film, polytetrafluoroethylene film, a polyether
ketone film, a polyether sulfone film or polymethylpentene film;
flame-retardant films or non-woven fabrics; and metal foils such as
a copper foil or aluminum foil are preferably used as a
heat-resistant substrate.
[0031] Such adhesive sheets are produced, for example, as follows.
A layer of the pressure-sensitive flame-retardant adhesive having
excellent heat resistance is formed on a releasing liner, and the
layer is transferred onto one surface or both surfaces of the
substrate; alternatively, the substrate is directly coated or
impregnated with the photopolymerizable composition without using
the releasing liner. The layer thus formed is irradiated with
ultraviolet rays to form a photopolymerized product, and the layer
is dried by heating to form the layer of the pressure-sensitive
flame-retardant adhesive having excellent heat resistance. An
appropriate method can be used depending on the kind of the
substrate used.
BEST MODE FOR PRACTICING THE INVENTION
[0032] The present invention is described in more detail below by
referring to the following examples. In the examples and the
comparative examples, all parts are by weight unless otherwise
indicated.
EXAMPLE 1
[0033] A premix composed of 60 parts of isononyl acrylate, 28 parts
of n-butyl acrylate, 12 parts of acrylic acid, and 0.1 part of
2,2-dimethoxy-2-phenylacetone (photopolymerization initiator) was
partially polymerized by exposing it to ultraviolet rays in a
nitrogen gas atmosphere to prepare a coatable syrup having a
viscosity of 4,500 centipoise. 0.2 Part of trimethylolpropane
triacrylate (crosslinking agent), 30 parts of propylene-modified
tetrabromobisphenol A (FG-3100, trade name, made by Teijin Limited,
melting point: 90 to 105.degree. C.) (flame retardant) and 10 parts
of antimony trioxide (flame retardant assistance) were added to 100
parts by the syrup to prepare a photopolymerizable composition.
[0034] This photopolymerizable composition was coated on a
substrate composed of a polyimide film having a thickness of 25
.mu.m, and the layer coated was subjected to a photopolymerization
treatment by irradiating with ultraviolet rays from a high-pressure
mercury lamp having an intensity of 5 mW/cm.sup.2 at 900
mj/cm.sup.2 in a nitrogen gas atmosphere. The photopolymerized
layer was then dried at 130.degree. C. for 5 minutes with a hot
blast circulating dryer to form a layer of a pressure-sensitive
flame-retardant adhesive having a thickness of 50 .mu.m. Thus an
adhesive sheet was prepared.
EXAMPLE 2
[0035] A photopolymerizable composition was prepared in the same
manner as in Example 1 except that a carbonyl-modified
tetrabromobisphenol A oligomer (FG-8100, trade name, made by Teijin
Limited, melting point: 165 to 180.degree. C.) was used as the
flame retardant. Further, using this photopolymerizable
composition, an adhesive sheet was prepared in the same manner as
in Example 1.
EXAMPLE 3
[0036] A photopolymerizable composition was prepared in the same
manner as in Example 1 except that a premix composed of 90 parts of
2-ethylhexyl acrylate, 10 parts of acrylic acid, and 0.1 part of
2,2-dimethoxy-2-phenylacetone (photopolymerization initiator) was
used. Further, using this photopolymerizable composition, an
adhesive sheet was prepared in the same manner as in Example 1.
EXAMPLE 4
[0037] A photopolymerizable composition was prepared in the same
manner as in Example 3 except that a carbonyl-modified
tetrabromobisphenol A oligomer (FG-8100, trade name, made by Teijin
Limited, melting point: 165 to 180.degree. C.) was used as a flame
retardant. Further, using this photopolymerizable composition, an
adhesive sheet was prepared in the same manner as in Example 1.
COMPARATIVE EXAMPLE 1
[0038] A photopolymerizable composition was prepared in the same
manner as in Example 1 except that 30 parts of the flame retardant
(propylene-modified tetrabromobisphenol A) and 10 parts of the
flame retardant assistant (antimony trioxide) were not used.
Further, using this photopolymerizable composition, an adhesive
sheet was prepared in the manner as in Example 1.
COMPARATIVE EXAMPLE 2
[0039] A photopolymerizable composition was prepared in the same
manner as in Example 1 except that 50 parts of chlorinated paraffin
(ENPARA 40, trade name, made by AJINOMOTO CO., INC., liquid at
normal temperature (i.e., melting point: lower than normal
temperature)) was used as the flame retardant and 20 parts of
antimony trioxide was used as the flame retardant assistant.
Further, using this photopolymerizable composition, an adhesive
sheet was prepared in the same manner as in Example 1.
COMPARATIVE EXAMPLE 3
[0040] 90 Parts of 2-ethylhexyl acrylate, 10 parts of acrylic acid,
210 parts of ethyl acetate, and 0.4 part of
2,2-azobis-isobutyronitrile were charged with a flask. After
sufficiently replacing the atmosphere in the system with a nitrogen
gas, a solution polymerization was conducted by heating to a
temperature of from 60 to 80.degree. C. with stirring. An acrylic
polymer solution having a viscosity of 120 poises, a conversion of
99.2% by weight, and a solid content of 31.4% by weight was
obtained.
[0041] 2.0 Parts of a polyfunctional isocyanate compound
(crosslinking agent), 30 parts of propylene-modified
tetrabromobisphenol A (FG-3100, trade name, made by Teijin Limited,
melting point: 90 to 105.degree. C.) (flame retardant) and 10 parts
by antimony trioxide (flame retardant assistant) were added to 100
parts of the acrylic polymer solution to form a pressure-sensitive
flame-retardant adhesive. This adhesive was coated on a substrate
composed of a polyimide film having a thickness of 25 .mu.m. After
drying the coated layer at 40.degree. C. for 5 minutes in a hot
blast dryer, the coated layer was further dried at 130.degree. C.
for 5 minutes to form a layer of the pressure-sensitive
flame-retardant adhesive having a thickness of 50 .mu.m. Thus an
adhesive sheet was prepared.
[0042] The adhesive sheets obtained in Examples 1 to 4 and
Comparative Examples 1 to 3 were examined for adhesive force,
holding power (shear holding power), and flame retardance in the
following manners. The measurement results are shown in Table 1
below.
[0043] Adhesive force:
[0044] The adhesive sheet was cut into a width of 20 mm to prepare
a test piece. Using a stainless steel plate as an adherent, 180
degree releasing was performed according to JIS Z 1522, and the
adhesive force (g/20 mm width) in this case was measured.
[0045] Holding power:
[0046] The adhesive sheet was cut into a width of 10 mm to prepare
a test piece. This test piece was adhered to an aluminum plate such
that the adhered area was 20 mm.times.10 mm. The assembly was
allowed to stand for 30 minutes at 80.degree. C. A load of 500 g
was applied to the end of the test piece, and the time of falling
by slipping was measured. The mark (*) in Table 1 shows that in the
measurement, the layer of the pressure-sensitive flame-retardant
adhesive caused cohesive failure and fell down.
[0047] Flame retardance test:
[0048] According to a thin material vertical combustion test method
of UL-94, combustion time of the adhesive sheet was determined.
1 TABLE 1 Flame retardance Adhesive force Holding power (Flame
retardant time) (g/20 mm width) (80.degree. C.) (sec) Example 1 950
200 or more 2 Example 2 850 200 or more 5 Example 3 900 200 or more
2 Example 4 800 200 or more 5 Comparative 1,010 200 or more 52
Example 1 Comparative 1,100 5* 10 Example 2 Comparative 650 5* 5
Example 3
[0049] As is apparent from the results shown in Table 1, it cam be
seen that in Examples 1 to 4, pressure-sensitive flame-retardant
adhesives which have excellent adhesive force and holding power and
also have a flame retardance, and the adhesive sheets using the
adhesives are obtained by irradiating the photopolymerizable
compositions with ultraviolet rays, but in Comparative Examples 1
to 3, the samples obtained are poor in at least one of the adhesive
force, the holding power and the flame-retardance.
INDUSTRIAL APPLICABILITY
[0050] As described above, the present invention can provide a
pressure-sensitive flame-retardant adhesive and the adhesive sheets
thereof, which have excellent adhesive properties such as adhesive
force, holding power, etc., and also have a self fire-extinguishing
property which instantaneously extinguishes fire , by using a
(meth)acrylic acid alkyl ester as the main component, compounding a
photopolymerization initiator, a specific crosslinking agent and a
specific flame retardant with the ester to prepare a
photopolymerizable composition, and polymerizing and curing the
composition by irradiating it with ultraviolet rays. Those can
suitably be used in the field requiring a high flame-retardance and
a strong adhesive property, such as fixation of electronic parts,
building materials, vehicles, aircraft, ships, etc.
* * * * *