U.S. patent application number 15/524613 was filed with the patent office on 2017-12-07 for curable adhesive compositions for flexible substrates.
The applicant listed for this patent is SAES GETTERS S.P.A.. Invention is credited to Jiabril GIGLI, Marco MUDU, Paolo VACCA.
Application Number | 20170349794 15/524613 |
Document ID | / |
Family ID | 55070095 |
Filed Date | 2017-12-07 |
United States Patent
Application |
20170349794 |
Kind Code |
A1 |
VACCA; Paolo ; et
al. |
December 7, 2017 |
CURABLE ADHESIVE COMPOSITIONS FOR FLEXIBLE SUBSTRATES
Abstract
A thermally or photo curable adhesive composition containing a
bisphenol F epoxy resin and a bisphenol A epoxy resin in a ratio
between 2 and 10. The composition further contains at least one
epoxy acrylate component and a rubber modified bisphenol. The
adhesive composition is applicable by a melt or liquid coating
technique and undergoes curing upon exposure to heat or radiation,
showing improved viscoelastic properties and suitable to provide a
cured product having superior durability.
Inventors: |
VACCA; Paolo; (MILANO,
IT) ; MUDU; Marco; (RHO, IT) ; GIGLI;
Jiabril; (LEGNANO, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAES GETTERS S.P.A. |
Lainate |
|
IT |
|
|
Family ID: |
55070095 |
Appl. No.: |
15/524613 |
Filed: |
October 14, 2016 |
PCT Filed: |
October 14, 2016 |
PCT NO: |
PCT/EP2016/074800 |
371 Date: |
May 4, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09J 163/00 20130101;
C09J 163/00 20130101; C08G 59/226 20130101; C08L 63/00 20130101;
C09J 11/08 20130101; C08G 59/182 20130101; C08G 59/245 20130101;
C08L 63/00 20130101 |
International
Class: |
C09J 163/00 20060101
C09J163/00; C09J 11/08 20060101 C09J011/08 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 19, 2015 |
IT |
102015000062578 |
Claims
1. A curable adhesive composition containing a bisphenol F epoxy
resin, a bisphenol A epoxy resin and at least one epoxy acrylate
component, wherein the weight ratio of bisphenol F with respect to
bisphenol A is comprised between 2 and 10 and wherein said
composition further contains a rubber modified epoxy resin.
2. The curable composition according to claim 1 wherein said weight
ratio of bisphenol F with respect to bisphenol A is comprised
between 4 and 8.
3. The curable composition according to claim 1 wherein said
bisphenol F is a liquid epoxy resin having number average molecular
weights lower than 700 gr/mol.
4. The curable composition according to claim 1 wherein the weight
ratio of said at least one epoxy acrylate component with respect to
said at least one rubber modified epoxy resin is comprised between
0.1 and 1.
5. The curable composition according to claim 1 wherein said rubber
modified epoxy resin is present in amount of 1 to 10 parts by
weight, based on 100 parts by weight of the whole curable adhesive
composition.
6. The curable composition according to claim 1 wherein said rubber
modified epoxy resin contains at least one between butadiene and
acrylonitrile.
7. The curable composition according to claim 1 wherein said epoxy
acrylate component is present in amount of 1 to 5 parts by weight,
based on 100 parts by weight of the whole curable adhesive
composition.
8. The curable composition according to claim 1 wherein said at
least one epoxy acrylate component is selected from glycidyl
acrylate and glycidyl methacrylate.
9. The curable composition according to claim 1 wherein said
composition further contains at least one thermoplastic filler.
10. The curable composition according to claim 9 wherein said at
least one thermoplastic filler is selected from poly(methyl
methacrylate-co-ethylene glycol dimethacrylate), poly(methyl
methacrylate-co-ethyl acrylate), poly(styrene-co-divinylbenzene)
and polymethysilsesquioxane.
11. The curable composition according to claim 1 wherein said
composition further contains at least one thermal initiator.
12. The curable composition according to claim 11 wherein said at
least one thermal initiator is selected from ethylenediamine,
trimethylhexamethylendiamine, diethylenetriamine,
2-hydroxyethyldiethylenetriamine, dipropylenetriamine,
triethylenetetramine, tetraethylenepentamine, diproprenediamine,
diethylaminopropylamine, dimethylaminopropylamine,
m-xylylenediamine, N-aminoethylpiperazine, methane diamine,
isophoronediamine, cyclohexylpropylenediamine. Preferred examples
of anhydride curing agent are methyltetrahydrophtalic anhydride,
methyl endomethylenetetrahydrophthalic anhydride,
methylhexahydrophthalic anhydride and dodecenylsuccinic
anhydride.
13. The curable composition according to claim 1 wherein said
composition further contains at least one UV photoinitiator.
14. The curable composition according to claim 13 wherein said at
least one UV photoinitiator is selected from triphenylsulfonium
salts, methyldiphenylsulfonium salts, dimethylphenylsulfonium
salts, diphenylnaphthylsulfonium salts and
di(methoxynaphthyl)methylsulfonium salts, triphenylsulfonium
hexafluorophosphate, methyldiphenylsulfonium hexafluorophosphate,
dimethylphenylsulfonium hexafluorophosphate,
diphenylnaphthylsulfonium hexafluorophosphate and
di(methoxynaphthyl)methylsulfonium hexafluorophosphate.
15. The curable composition according to claim 1 wherein said
composition further contains at least one visible
photoinitiator.
16. The curable composition according to claim 15 wherein said at
least one visible photoinitiator is selected from
2,4,5,7-tetraiodo-3-hydroxy-6-fluorone and
5,7-diiodo-3-butoxy-6-fluorone.
Description
[0001] The present invention relates to thermally or photo curable
adhesive compositions that are applicable by a melt or liquid
coating technique and undergoes curing upon exposure to a heat or
radiation, and more particularly to adhesive compositions with
improved viscoelastic properties and suitable to provide a cured
product having superior durability.
STATE OF THE ART
[0002] Adhesives have been widely used to bond various elements for
their solvent-free nature and excellence in environmental
resistance. For example, various types of curable adhesive
compositions have been proposed to be applied by melt or liquid
coating and subsequent curing by irradiation or heat in order to
exhibit high bond strength. Many adhesive technologies can be
formulated into composition suitable to be used as sealants, i.e.
adopted to fill the gap between substrates and joints them.
[0003] Among such compositions, a large number of curable adhesives
is based on a ring-opening reaction of an epoxy resin, i.e. these
curable adhesive compositions obtain a high bond strength through a
ring-opening polymerization of an epoxy group. Up to now, the
selection of the specific epoxy compound and the inclusion of a
phenol-containing compound has been attempted to achieve
improvements in bond strength or heat resistance after cure.
Adherends are bonded together by these curable hot-melt or liquid
adhesives subsequently submitted to a curing treatment, based on
exposure to heat or radiation.
[0004] Generally, in the case a photoreactive composition is
selected (i.e. containing a cationic photoinitiator), it is not
required that the cationically curable adhesive is irradiated
continually until it is fully cured. In fact, once such an adhesive
is irradiated, curing reaction in which radiation-generated
cationic active species participate goes ahead even when this
irradiation is stopped. If the mechanism of polymerization is well
understood, a cationically photoreactive hot-melt or liquid
adhesive may be used also when adherends are laminated by the
adhesive and they prevent passage of a radiation, e.g., when they
are opaque adherends. In order to extend the pot life of the
adhesive composition, a component commonly called "cure retarder"
is generally incorporated in the cationically photoreactive
adhesive.
[0005] In the International patent application WO9513315, an
epoxy/polyester based hot-melt composition which contains polyester
that assumes a solid form at ordinary temperature, an epoxy resin
and a cationic photoinitiator is disclosed. Due to the
incorporation of the polyester that assumes a solid form at
ordinary temperature, that adhesive revealed high strength
immediately after lamination, eliminating the need of a clamping or
other provisional fixing operation before curing completes.
However, in the case where the composition excludes the solid
polyester and incorporates the solid epoxy resin, the
photoinitiator and optionally a low molecular weight
hydroxyl-containing material, it is described to reveal low
strength immediately after lamination.
[0006] The Japanese patent application JPH10330717 discloses a
photoreactive adhesive composition comprising Bisphenol A type
epoxy resin, polytetramethylene glycol and a cationic
polymerization initiator. "Bisphenols" indicates a group of
chemical compounds with two hydrophenyl functionalities and most of
them are based on diphenylmethane. Bisphenol A (systematic name
2,2-bis(4-hydroxyphenyl)propane) is the most popular representative
of this group. JPH10330717 further discloses Bisphenol F type epoxy
resin as a suitable alternative to Bisphenol A type epoxy resin,
suggesting to a replacement between them as excluding alternatives
(i.e. using only Bisphenol A type or only Bisphenol F type as epoxy
component) or as equivalent alternatives (i.e. using a different
ratio between Bisphenol A and Bisphenol F to obtain a prefixed
amount of the epoxy component without effect to the properties of
the adhesive composition or the consequent cured material). For
example, a photoreactive adhesive formulation where in combination
of 2 parts by weight of a liquid epoxy resin, 4 parts by weight of
polytetramethylene ether glycol and 0.8 parts by weight of cationic
photoinitiator, 15 parts by weight of bisphenol A epoxy resin and
10 parts by weight of bisphenol A epoxy resin have been replaced by
15 parts by weight of bisphenol F epoxy resin and 10 parts by
weight of bisphenol F epoxy resin (without any significant effect
on dry adhesion and chemical resistance
[0007] The International patent application WO02055625 discloses a
photoreactive hot-melt adhesive composition which contains a
bisphenol F epoxy resin, a cationic photoinitiator and a compound
preferably selected between a copolymer of tetramethylene oxide and
ethylene oxide or a copolymer of tetramethylene oxide and propylene
oxide. WO02055625 moreover describes the possibility that bisphenol
F is mixed to Bisphenol A in the epoxy component of the adhesive if
their respective weight ratio is at least 12.5, teaching that the
replacement of bisphenol F with bisphenol A exhibits some
drawbacks, as for example an insufficient resistance against
hydrophilic liquids. Moreover, a strong increasing in glass
transition temperature and viscosity characterize the compositions
disclosed in WO02055625. Unlike the above prior-art document, the
European patent application EP2377903 discloses an adhesive
composition wherein bisphenol A is present as main epoxy resin in
combination with bisphenol F in order to balance some film adhesive
properties, as its strength and the connection resistance.
EP2377903, anyway, is silent about how modify those compositions to
improve many other adhesive properties, as for example its
flexibility after the film formation obtained by solvent
evaporation. The U.S. Pat. Nos. 5,596,024 and 5,854,325 disclose
photo-polymerisable epoxy adhesive compositions wherein epoxy
acrylate components are used in association to an epoxy resin in
order to achieve an excellent preservative stability without giving
rise to failure under hot and humid conditions, but it is silent on
how said composition should be modified and provide high adhesive
strength immediately after their application and have excellent
flexibility and durability after curing. In particular U.S. Pat.
No. 5,854,325 discloses compositions mainly based on the use of
bisphenol A or, as alternative, bisphenol F epoxy resins.
DESCRIPTION OF THE INVENTION
[0008] It is an object of the present invention to provide a
curable adhesive composition which is readily applicable to an
adherend, completes curing soon after irradiation or thermal
exposure, reveals high adhesive strength immediately after
lamination, without requiring a long period of aging, and moreover
which exhibits excellent flexibility and durability after curing.
In accordance with a broad aspect of the present invention, a
curable adhesive composition is provided containing a bisphenol F
epoxy resin and a bisphenol A epoxy resin in a weight ratio that is
comprised between 2 and 10 and further containing at least one
epoxy acrylate component in association with at least one rubber
modified bisphenol, such as a rubber modified epoxy resin. Rubber
modified bisphenols are epoxy resins where rubber chains are
covalently linked to the bisphenol unit. These components are
generally obtained through the reaction of reactive group at the
chain ends of rubber copolymer, copolymer that displays rubber-like
elasticity, and epoxy groups. Typical adopted reactive group at the
chain ends are carboxylic acid or amine groups and the adopted
rubbers usually are copolymers of butadiene and acrylonitrile. In a
preferred embodiment of the present invention, the curable adhesive
composition is provided containing a bisphenol F epoxy resin and a
bisphenol A epoxy resin in a weight ratio that is comprised between
4 and 8.
[0009] As effect of the inclusion of the bisphenol F epoxy resin as
a reactive component, the curable adhesive composition in
accordance with the present invention can provide a cured product
with improved such physical properties as toughness, durable
adhesion and flexibility but only if said bisphenol is used is in
association with a corresponding amount of bisphenol A epoxy resin
as above disclosed, with at least one rubber modified epoxy resin
and with at least one epoxy acrylate component. Rubber modified
epoxy resins deriving from the family of copolymers of butadiene
and acrylonitrile are particularly preferred for the formulation of
compositions according to the present invention.
Carboxyl-terminated butadiene-acrylonitrile resins can be also
adopted.
[0010] In said first particular aspect of the invention, the
curable adhesive composition contains the rubber modified epoxy
resin component in the amount of 1-10 parts by weight, based on 100
parts by weight of all the curable adhesive composition. This
rubber modified epoxy resin component may be selected from Epikote
03161 manufactured by Hexion, KR-208 and KR-309 manufactured by
Kukdo Chemical (Kunshan) co. LTD., EPR 2000 manufactured by Adeka
Corporation.
[0011] As effect of the inclusion of the rubber-modified epoxy
resin as a reactive component, the curable adhesive composition in
accordance with the present invention can provide a cured product
with improved reactivity but only if said rubber-modified epoxy
resin is used in association with a corresponding amount of
bisphenol A and bisphenol F epoxy resins and with at least one
epoxy acrylate component. In fact, even if the use of
rubber-modified epoxy resin in association with bisphenol epoxy
resin has been disclosed, for example, by the International patent
application WO 2013142751 in order to allow the adduct to further
react when the adhesive is cured, adhesion before curing as well
final flexibility and durability can be obtained only when adhesive
composition fails into the present invention, i.e. it additionally
comprises epoxy acrylate component and bisphenol A and bisphenol F
are present in a corresponding ratio.
[0012] In particular , the curable adhesive composition contains
the epoxy acrylate component in the amount of 1-5 parts by weight,
based on 100 parts by weight of all the curable adhesive
composition. This epoxy acrylate component is a reactive monomer
where acrylic functionalities are combined to glycidyl functional
groups or bisphenol unit: for example it may be selected from
glycidyl acrylate, glycidyl methacrylate, bisphenol A diacrylate,
bisphenol F diacrylate. Epoxy acrylates components are generally
used in combination with multifunctional monomers like
trimethylolpropane trimethacrylate, trimethylolpropane triacrylate
to increase the curing rate. In a particular embodiment of
formulations according to the present invention a blend of glycidyl
acrylate and trimethylolpropane triacrylate can be adopted.
[0013] The type of the bisphenol F epoxy resin is not particularly
binding. For example, bisphenol F epoxy resins having average
molecular weights in the approximate range of 300-10,000 gr/mol can
be suitably used. Specific examples thereof include those sold
under the names of EPICOAT 4004P and EPICOAT 4010P and manufactured
by Yuka-Shell Epoxy Co., Ltd. Other type of suitable bisphenol F
can be a liquid epoxy resin having number average molecular weights
lower than 700 gr/mol as for example that sold under the name Epon
Resin 862 and manufactured by Hexion. The bisphenol F epoxy resin
undergoes ring-opening polymerization when the cationic
photoinitiator is activated by irradiation and imparts excellent
bond strength to the photoreactive hot-melt adhesive composition in
accordance with the present invention. This is probably because the
methylene bridge in bisphenol F epoxy resin allows an easier
skeleton rotation making it more flexible and thus provides a cured
product which shows improved stress relaxation, compared to the
bisphenol A epoxy resin. Because of the missing methyl groups, the
viscosity of bisphenol F resins is typically lower than that of
bisphenol A. Also, the bisphenol F epoxy resin acts to increase the
resistance of the cured product to water and other hydrophilic
liquids, when reacted with the epoxy acrylate component. At the
same time, the bisphenol A epoxy resin is particularly useful for
its ability to impart improved resistance against hydrophilic
liquids to a bonded laminate. The type of the bisphenol A epoxy
resin is not particularly binding. For example, unmodified
bisphenol A epoxy resins having average molecular weights lower
than 1000 gr/mol can be suitably used. Specific examples thereof
include those sold under the names of Epon 828 manufactured by
Hexion , D.E.R. 332 manufactured by DOW Chemical, Araldite GY 6010
manufactured by Huntsman.
[0014] Although its molecular weight is not particularly binding, a
thermoplastic filler can be advantageously added to the composition
according to the present invention. It can be selected from
poly(methyl methacrylate-co-ethylene glycol dimethacrylate),
poly(methyl methacrylate-co-ethyl acrylate),
poly(styrene-co-divinylbenzene), polymethysilsesquioxane and it
preferably has a weight average molecular weight of 1,000 gr/mol or
higher for its ability to improve heat-resistant adhesion.
Preferably, the particle size of the thermoplastic filler is
smaller than 20 um and the amount of the thermoplastic filler
incorporated is within the range of 1-8 parts by weight, based on
100 parts by weight corresponding to the total weight of the
composition according to the present invention. If compared to
bisphenol F based composition in the state of the art, this
concentration of thermoplastic filler can be lowered up to be
significantly less than 10% by weight of the compositions and this
can be useful to minimize its jeopardizing impact on the barrier
properties.
[0015] In the present invention, in the case of a thermally
adhesive composition, any curing agent can be suitably used as
thermal initiator, so long as it is activated by exposure to heat
to cause ring-opening polymerization of the epoxy resin. Preferred
examples of amine curing agent are ethylenediamine,
trimethylhexamethylendiamine, diethylenetriamine, 2-hydroxyethyl
diethylenetriamine, dipropylenetriamine, triethylenetetramine,
tetraethyl enepentamine, diproprenediamine,
diethylaminopropylamine, dimethylaminopropylamine,
m-xylylenediamine, N-aminoethylpiperazine, methane diamine,
isophoronediamine, cyclohexylpropylenediamine. Preferred examples
of anhydride curing agent are methyltetrahydrophtalic anhydride,
methyl endomethylenetetrahydrophthalic anhydride,
methylhexahydrophthalic anhydride, dodecenylsuccinic anhydride.
Curing agents react with glycidyl resins slowly at room
temperature, but higher temperatures induce a faster curing
mechanism. Moreover, curing agents can be also adopted like latent
hardener in formulating single-component thermally curable epoxy
resins. Preferred examples of latent hardener are dicyandiamide and
organic-acid hydrazide. In particular, dicyandiamide is normally
used in the form of fine powder or modified particles dispersed in
the resin ensuring a very long pot life.
[0016] In the case of thermally adhesive composition, the loading
of the curing agent is optimal when the number of active hydrogen
is equal to that of moles in epoxy groups. Generally for 25 parts
of an epoxy resin with equivalent number of 200 g/eq, 25-50 parts
by weight have to be adopted for a curing agent with 200-100 number
of active hydrogen, based on 100 parts by weight of the overall
composition weight, allowing a complete polymerization of the
adhesive composition with thermal treatment at temperature in the
range between 70-120.degree. C. for a time between 60 and 20
minutes.
[0017] In the present invention, in the case of a photocurable
adhesive composition, any cationic photoinitiator can be suitably
used, so long as it is activated by exposure to radiation to cause
ring-opening polymerization of the epoxy resin. Examples of
cationic photoinitiators include sulfonium salts, iodonium salts,
onium. Preferred among such cationic photoinitiators are antimonium
salts and triarylsulfonium hexafluoroantimonate salts have been
found to be particularly useful to the present invention. As
alternative, cationic photoinitiator can be choosen among
triphenylsulfonium salts, methyldiphenylsulfonium salts,
dimethylphenylsulfonium salts, diphenylnaphthylsulfonium salts and
di(methoxynaphthyl)methylsulfonium salts. Preferred among such
aromatic sulfonium salts are aromatic sulfonium salts with
hexafluorophosphate ions (PF6<->) as counter ions as, for
example, triphenylsulfonium hexafluorophosphate,
methyldiphenylsulfonium hexafluorophosphate,
dimethylphenylsulfonium hexafluorophosphate,
diphenylnaphthylsulfonium hexafluorophosphate and
di(methoxynaphthyl)methylsulfonium hexafluorophosphate.
[0018] In the case of a photocurable adhesive applied on plastic
substrates and a curing process promoted through a layer where UV
blockers or light stabilizers are adopted, photoinitiator mixture
with light absorption in the long wavelength UV region or in
visible range can be suitably used. Examples of fluorone dyes are
2,4,5,7-Tetraiodo-3-hydroxy-6-fluorone,
5,7-diiodo-3-butoxy-6-fluorone, also adopted in combination with
Iodonium salt or other coinitiators.
[0019] The amount of the cationic photoinitiator may be varied
depending upon the type and intensity of the radiation, the types
and amounts of the epoxy resins, the type of the cationic
photoinitiator used and the like. Preferably, the cationic
photoinitiator is incorporated in the amount of 0.05-10 parts by
weight, based on 100 parts by weight of the overall composition
weight.
[0020] The type of the radiation used to cure the composition is
not particularly specified if it can cause the cationic
photoinitiator to generate cations, and can be suitably chosen
depending on the type of the cationic photoinitiator used.
[0021] The applicable radiation may be in the ultraviolet range or
in visible range. Particularly in the case where a triarylsulfonium
hexafluoroantimonate salt is used as the cationic photoinitiator,
the radiation preferably includes a wavelength of 350-400 nM.
Particularly in the case where a fluorone dye is used as the
cationic photoinitiator, the radiation preferably includes a
wavelength of 400-550 nm. The energy exposure cannot be readily
determined because it is varied depending on the type of the
cationic photoinitiator used and the thickness and spread of the
photoreactive hot-melt adhesive composition coated on an adherend,
but may preferably be in the range of 0.001 J-15 J. The exposure
time cannot be specified in a wholesale manner because it is varied
depending on the intensity of the radiation, the type of the epoxy
resin used and the like, but is generally sufficient if within the
range of 1-120 seconds. When the adhesive is coated in a relatively
thick manner, the exposure time may preferably be extended beyond
the above-specified range.
[0022] The adhesive composition in accordance with the present
invention may further contain other components, if necessary,
within the range that does not impede the purposes of the present
invention. Examples of such components include adhesion improvers,
sensitizers, dehydrating agents, antioxidants, stabilizers,
plasticizers, waxes, fillers, spacers, flame retardants, blowing
agents, antistatic agents, fungicides, viscosity control agents and
the like. Applicable components are not limited to those listed
above. Any combination of the above-listed components may be
added.
[0023] The type of the adherend to which the adhesive composition
in accordance with the present invention is applied is not
particularly limited. Plastic adherends can be suitably used,
including those made from polyester resins such as polyethylene
terephthalate, polycarbonate and polyallylate; acrylic resins; and
the like. The photoreactive hot-melt adhesive composition in
accordance with the present invention can also be applied to
adherends made from a wide range of materials including plastics as
polycarbonate, polyimide, polyetherimide other than polyethylene
terephthalate and polyethylene naphthalate, rubbers such as
ethylene propylene rubber; metals such as iron and aluminum and
alloys; cellulosic materials such as wood and paper; leathers; and
the like.
[0024] The present invention will be further explained by the
following non-limiting examples.
EXAMPLE 1
[0025] 77.5 parts by weight of a liquid bisphenol F epoxy resin,
8.7 parts by weight of a liquid bisphenol A epoxy resin, 8.7 parts
by weight of poly (acrylonitrile-co-butadiene) modified bisphenol
resin, 1 part by weight of a blend of glycidyl acrylate and
trimethylolpropane triacrylate, 4.5 parts by weight of poly(methyl
methacrylate-co-ethylene glycol dimethacrylate), 4.5 parts by
weight of triphenylsulfonium salts are mixed together in a kneading
machine to obtain a photoreactive adhesive composition.
[0026] The obtained liquid material has been cured by applying an
irradiance of 100 mW/cm2 for 120 s with .lamda.=365nm
EXAMPLE 2
[0027] 72.5 parts by weight of a liquid bisphenol F epoxy resin,
11.2 parts by weight of a liquid bisphenol A epoxy resin, 6.2 parts
by weight of poly (acrylonitrile-co-butadiene) modified bisphenol
resin, 5 parts by weight of a blend of glycidyl acrylate and
trimethylolpropane triacrylate, 4.5 parts by weight of poly(methyl
methacrylate-co-ethylene glycol dimethacrylate), 4.5 parts by
weight of triphenylsulfonium salts are mixed together in a kneading
machine to obtain a photoreactive adhesive composition.
[0028] The obtained liquid material has been cured by applying an
irradiance of 100 mW/cm2 for 120 s with .lamda.=365 nm
EXAMPLE 3
[0029] 72.5 parts by weight of a liquid bisphenol F epoxy resin,
11.2 parts by weight of a liquid bisphenol A epoxy resin, 6.2 parts
by weight of poly (acrylonitrile-co-butadiene) modified bisphenol
resin, 5 parts by weight of a blend of glycidyl acrylate and
trimethylolpropane triacrylate, 4.5 parts by weight of poly(methyl
methacrylate-co-ethylene glycol dimethacrylate), 21 parts by weight
of dicyandiamide are mixed together in a kneading machine to obtain
a thermally curable reactive adhesive composition
[0030] The obtained liquid material has been cured by applying a
heating process at 100.degree. C. for 30 min.
EXAMPLE 4
[0031] 72.5 parts by weight of a liquid bisphenol F epoxy resin,
11.2 parts by weight of a liquid bisphenol A epoxy resin, 6.2 parts
by weight of poly (acrylonitrile-co-butadiene) modified bisphenol
resin, 5 parts by weight of a blend of glycidyl acrylate and
trimethylolpropane triacrylate, 4.5 parts by weight of poly(methyl
methacrylate-co-ethylene glycol dimethacrylate), 0.5 parts by
weight of 2,4,5,7-Tetraiodo-3-hydroxy-6-fluorone, 2.5 parts by
weight of Iodonium salt are mixed together in a kneading machine to
obtain a photoreactive adhesive composition.
[0032] The obtained liquid material has been cured by applying an
irradiance of 100 mW/cm2 for 120 s with .lamda.=530 nm
EXAMPLE 5
Comparative: Weight Ratio Out of Range
[0033] 82.5 parts by weight of a liquid bisphenol F epoxy resin,
6.2 parts by weight of a liquid bisphenol A epoxy resin, 8.7 parts
by weight of poly (acrylonitrile-co-butadiene) modified bisphenol
resin, 1 part by weight of a blend of glycidyl acrylate and
trimethylolpropane triacrylate, 4.5 parts by weight of poly(methyl
methacrylate-co-ethylene glycol dimethacrylate), 4.5 parts by
weight of triphenylsulfonium salts are mixed together in a kneading
machine to obtain a photoreactive adhesive composition.
[0034] The obtained liquid material has been cured by applying an
irradiance of 100 mW/cm2 for 120 s with .lamda.=365 nm
EXAMPLE 6
Comparative: Lacking Rubber Modified Epoxy Resin
[0035] 72.5 parts by weight of a liquid bisphenol F epoxy resin,
11.2 parts by weight of a liquid bisphenol A epoxy resin, 5 parts
by weight of a blend of glycidyl acrylate and trimethylolpropane
triacrylate, 4.5 parts by weight of poly(methyl
methacrylate-co-ethylene glycol dimethacrylate), 4.5 parts by
weight of triphenylsulfonium salts are mixed together in a kneading
machine to obtain a photoreactive adhesive composition.
[0036] The obtained liquid material has been cured by applying an
irradiance of 100 mW/cm2 for 120 s with .lamda.=365 nm
EXAMPLE 7
Comparative: Epoxy Acrylate Replaced by Aliphatic Acrylate
[0037] 77.5 parts by weight of a liquid bisphenol F epoxy resin,
8.7 parts by weight of a liquid bisphenol A epoxy resin, 10 parts
by weight of aliphatic monoglycidyl ether of C12/C14-fatty alcohol,
1 part by weight of a blend of glycidyl acrylate and
trimethylolpropane triacrylate, 4.5 parts by weight of poly(methyl
methacrylate-co-ethylene glycol dimethacrylate), 4.5 parts by
weight of triphenylsulfonium salts are mixed together in a kneading
machine to obtain a photoreactive adhesive composition.
[0038] The obtained liquid material has been cured by applying an
irradiance of 100 mW/cm2 for 120 s with .lamda.=365 nm
EXAMPLE 8
Comparison Between the Compositions of Examples 1 to 7
[0039] In order to determine the transition from a mechanical solid
phase to a viscoelastic phase, the prepared liquid samples have
been submitted to calorimetric analysis. Differential Scanning
Calorimetry has been performed by means of a DSC 204 F1 Phoenix
equipment from Netzsch and connected to a Omnicure 2000 light
source and to a compressor cooling device. 20 mg of liquid samples
have been cured in aluminum crucibles and then submitted to a
heating scan at 10.degree. C./min in the range -50.degree.
C.-200.degree. C. The glass transition range has been determined by
considering the onset and the endpoint of the inflection
portion.
TABLE-US-00001 Bis F/ Glass transition Formulation Bis A range
(Tg)* [.degree. C.] Example 1 8.9 -5-13 Example 2 6.5 0-20 Example
3 6.5 10-25 Example 4 6.5 0-20 Example 5 13.3 90-100 Example 6 6.5
125-140 Example 7 8.9 60-80
* * * * *