Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
CURABLE BLENDS OF HYDROLYSABLE
POLYOXYPROPYLENES AND EPOXY RESINS
This application is a division of Canadian Patent
Application No. 2,056,360, filed April 3, 1991.
TECHNICAL FIELD
This invention relates to a novel curable resin
composition comprising a reactive silicon group-
containing oxypropylene polymer and an epoxy resin.
BACKGROUND ART
So far, epoxy resins have been used widely in such
fields as various molding materials, adhesives, paints,
plywoods and laminates. However, there are problems
common to these applications; disadvantageously, cured
products are brittle or fragile and, when epoxy resins
are used in adhesives, the peel strength is low.
Meanwhile, oxypropylene polymers having a reactive
silicon group (a group which is a silicon atom-
containing group with a hydroxyl group or a
hydrolyzable group being bound to the silicon atom and
can form a siloxane bond) have interesting
characteristics in that they can be cured at ambient
temperature to give rubber-like elastic substances.
Generally, however, they are disadvantageous in that
the strength of cured products is low, so that their
applications are restricted.
For markedly improving the disadvantageous
properties of both, namely the brittleness of cured
epoxy resins and the insufficient strength of cured
CA 02313359 2000-07-18
oxypropylene polymers, curable resin compositions in
which an epoxy resins and a reactive silicon group-
containing oxypropylene polymer are combined have been
proposed (e.g. Japanese Kokai Patent Publication No.
61-247723 and No. 61-268720).
However, it has so far been difficult to produce
oxypropylene polymers having a high molecular weight
with a narrow molecular weight distribution (high
monodispersity) and accordingly only reactive silicon
group-containing oxypropylene polymers having a broad
molecular weight distribution (high poiydispersity)
have been known.
Composition in which such oxypropylene polymers
having a broad molecular weight distribution cause
various inconveniences in practical use thereof; for
instance they have a high viscosity and are not easy to
handle before curing.
Recently, it has been reported that polyoxypro-
pylenes showing a narrow molecular weight distribution
can be produced. The present inventors found that
compositions comprising an epoxy resin and a polymer
derived from an oxypropylene polymer with a narrow
molecular weight distribution, which is used as the
main chain, by introducing a reactive silicon group
either internally or at the terminal of said chain,
have a low viscosity and
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are easy to handle before curing and, after curing,
give cured products having excellent tensile character-
istics and furthermore good chemical resistance and
water resistance. This finding has now led to comple-
tion of the present invention.
DISCLOSURE OF INVENTION
The curable resin composition of the invention
comprises
(A) an oxyprapylene polymer which contains, in its
main polymer chain, a repeating unit of the formula
C H 3
I
- C H - C H 2 - 0 -
and which has at least one silicon atom-containing
group (reactive silicon group) with a hydroxyl group or
a hydrolyzable group being bound to the silicon atom
and has an Mw/Mn (weight average molecular weight/
number average molecular weight) ratio of not more than
1.6 and a number average molecular weight (Mn) of not
less than 6,000, and
(B) an epoxy resin.
BEST MODE FOR CARRYING OUT THE INVENTION
The reactive silicon group contained in the
oxypropylene polymer, namely component (A), to be used
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in the practice of the invention is not limited to any
particular species but may typically include, for
example, groups of the following general formula (1)
1 2
R 2 _ b R 3 _ a
I
S i - O S i - X $ --- --- ( i
1
Xb m
In the above formula, RI and R2 each is an alkyl
group containing 1 to 20 carbon atoms, an aryl group
containing 6 to 20 carbon atoms, an aralkyl group
containing 7 to 20 carbon atoms or a triorganosiloxy
group of the formula (R')3Si0-. Where there are two or
more R1 or R2 groups, they may be the same or differ-
ent. R' is a monovalent hydrocarbon group containing 1
to 20 carbon atoms. The three R' groups may be the
same or different. X is a hydroxyl group or a hydro-
lyzable group and, where there are two or more X
groups, they may be the same or different. a is 0, 1,
2 or 3 and b is 0, 1 or 2. The number b may vary in
the m groups of the formula
i
R 2 - b
I
- S i - O -
I
X b
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m is an integer of 0 to 19. The following condition
shall be satisfied: a + Eb >-_ 1.
The hydrolyzable group represented by the above-
mentioned X is not particularly limited but may be any
hydrolyzable group known in the art. More specifical-
ly, there may be mentioned a hydrogen atom, a halogen
atom, an alkoxy group; an acyloxy group, a ketoximato
group, an amino group, an amido group, an acid amido
group, an aminoxy group, a mercapto group, an alkenyl-
oxy group and the like. Among these, the hydrogen atom
and alkoxy, acyloxy, ketaximato, amino, amido, aminoxy,
mercapto and alkenyloxy groups are preferred. From the
viewpoint of mild hydrolyzability and easy handling,
alkoxy groups, for example methoxy, are particularly
preferred.
One to three such hydrolyzable groups or~hydroxyl
groups may be bound to one silicon atom, and (a + Eb)
is preferably equal to 1 to 5. Where there are two or
more hydrolyzable groups or hydroxyl groups in the
reactive silicon group, they may be the same or differ-
ent.
The reactive silicon group may contain one silicon
atom or two or more silicon atoms. In the case of a
reactive silican group comprising silicon atoms linked
to one another via a siloxane bonding or the like, said
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group may contain about 20 silicon atoms.
Reactive silicon groups of the following general
formula (2) are preferred because of ready availabili-
ty.
2
R 3 - a
... ...
- S i - X a
In the above formula, R2, X and a are as defined above.
Specific examples of R1 and R2 appearing in the
general formula .(1) given hereinabove include, among
others, alkyl groups, such-as methyl and ethyl, cyclo-
alkyl groups, such as cyclohexyl, aryl groups, such as
phenyl, aralkyl groups, such as benzyl, and triorgano-
siloxy groups of the formula (R')3Si0- in which R' is
methyl or phenyl. The methyl group is particularly
preferred as R1, R2 and/or R'.
The oxypropylene polymer should recommendably
contain at least one, preferably i.l to S reactive
silicon groups per molecule thereof. When the number
of reactive silicon groups contained in the polymer on
the per-molecule basis is less than 1, the curability
becomes inadequate and a good rubber elastic behavior
can hardly be developed.
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The reactive silicon group may be positioned
terminally or internally to the molecular chain of the
oxypropylene polymer. When the reactive silicon group
occurs terminally to the molecular chain, the oxypro-
pylene polymer component contained in the finally
formed cured product can have an increased number of
effective network chains and therefore a rubber-like
cured product showing high strength, high elongation
and low elasticity can readily be obtained.
The oxypropylene polymer, which constitutes the
main polymer chain in the component (A) to be used in
the practice of the invention, contains a repeating
unit of the formula
C H
1
- C H - C H 2 - O -
This oxypropylene polymer may be straight-chained
or branched, or a mixture of these. It may further
contain another monomer unit or the like. It is
preferable, however, that the polymer contains the
monomer unit represented by the above formula in an
amount of at least 50°s by weight, more preferably at
least 80~ by weight.
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The oxypropylene polymer that can effectively be
used has a number average molecular weight (Mn) of not
less than 6,400, preferably 6,000 to 30,000. Further-
more, in this oxypropylene polymer, the weight average
molecular weight/number average molecular weight ratio
(Mw/Mn) is not more than 1.6, hence the molecular
weight distribution is very narrow (the polymer is
highly monodisperse). The value of Mw/Mn should
preferably be not higher than 1.5, more preferably not
higher than 1.4. The molecular weight distribution can
be measured by various methods. Generally, however,
the measurement method most commonly used is gel
permeation chromatography (GPC). Since the molecular
weight distribution is narrow in that manner despite
the great number average molecular weight, the compo-
sition of the invention has a low viscosity before
curing, hence is easy to handle and, after curing,
shows a good.rubber-like elastic behavior and When used
as an adhesive, produces an excellent adhesive streng-
th.
The reactive silicon group-containing oxypropylene
polymer to be used as component (A) in the practice of
the invention is preferably prepared by introducing a
reactive silicon group into an oxypropylene polymer
having a functional group.
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Oxypropylene polymers having a high molecular
weight with a narrow molecular weight distribution and
having a functional group can hardly be obtained by the
conventional method of polymerizing oxypropylene
(anionic polymerization using a caustic alkali) or by
the chain extension reaction method using oxypropylene
polymers obtained by said conventional method as
starting materials. They can be obtained, however, by
such special polymerization methods as those described
in Japanese Rokai Patent Publications Nos. 61-197631,
61-215622, 61-215623 and 61-218632 and Japanese Patent
Publications Nos. 46-27250 and 59-15336 and elsewhere.
Since introduction of a reactive silicon group tends to
result in a broadened molecular weight distribution as
compared with that before introduction, the molecular
weight distribution of the polymer before introduction
should preferably be as narrow as possible_
The reactive silicon group introduction can be
carried out by any appropriate known method. Thus, for
example, the following methods may be mentioned.
(1) Rn oxypropylene polymer having a terminal func-
tional group, for example a hydroxyl group, is reacted
with an organic compound having an active group or
unsaturated group reactive with said function group and
then the resulting reaction product is hydrosilylated
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by treatment with a hydrosilane having a hydrolyzable
group.
(2) An oxypropylene polymer having a terminal func-
tional group (hereinafter referred to as functional
group Y), such as a hydroxyl, epoxy or isocyanato
group, is reacted with a compound having a functional
group (hereinafter referred to as functional group Y')
reactive with said functional group Y and a reactive
silicon group.
Typical examples of the silicon compound having
the functional group Y' include, but are not limited
to, amino group-containing silanes, such as y-(2-amino-
ethyl)aminopropyltrimethoxysilane, Y-(2-aminoethyl)-
aminopropylmethyldimethoxysilane and Y-aminopropyl-
triethoxysilane; mercapto group-containing silanes,
such as Y-mercaptopropyltrimethoxysilane and y-mer-
captopropylmethyldimethoxysilane; epoxysilanes, such as
Y-glycidoxypropyltrimethoxysilane and S-(3,4-epoxy
cyclohexyl)ethyltrimethoxysilane; vinyl type unsatu-
rated group-containing silanes, such as vinyltri-
ethoxysilane, Y-methacryloyloxypropyltrimethoxysilane
and Y-acryloyloxypropylmethyldimethoxysilane; chlorine
atom-containing silanes, such as Y-chloropropyltri-
methoxysilane; isocyanato-containing silanes, such as
Y-isocyanatopropyltriethoxysilane and Y-isocyanatopro-
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pylmethyldimethoxysilane; and hydrosilanes, such as
methyldimethoxysilane, trimethoxysilane and methyl-
diethoxysilane.
Among the methods mentioned above, the method (1),
and the method (2) comprising the reaction between a
polymer having a terminal hydroxyl group and a compound
having an isocyanato group and a reactive silicon group
are preferred.
As examples of the epoxy resin which is to be used
as component (B) in the practice of the invention,
there may be mentioned epichlorohydrin-bisphenol A type
epoxy resins, epichlorohydrin-bisphenol F type epoxy
resins, tetrabromobisphenol A glycidyl ether and like
flame-resistant epoxy resins, novolak type epoxy
resins, hydrogenated bisphenol A type epoxy resins,
bisphenol A-propylene oxide adduct glycidyl ether type
epoxy resins, p-hydroxybenzoic acid glycidyl ether
ester type epoxy resins, m-aminophenol-based epoxy
resins, diaminodiphenylmethane-based epoxy resins,
urethane-modified epoxy resins, various alicyclic epoxy
resins, N,N-diglycidylaniline, N,N-diglycidyl-o-tolui-
dine, triglycidyl isocyanurate, polyalkylene glycol
diglycidyl ether, other glycidyl ethers with a poly-
hydric alcohol such as glycerol, hydantoin type epoxy
resins, and epoxidation products from unsaturated
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polymers such as petroleum resin. These are not
limitative examples but those epoxy resins that are in
general use can be used. Among these epoxy resins,
those that have, in their molecule, at least two epoxy
groups of the formula
-CH - CIi2
O
are preferred.since they are highly reactive in curing
and cured products therefrom can readily form a three-
dimensional network. As more preferred ones, there may
be mentioned bisphenol A type epoxy resins and novolak
type epoxy resins.
In the practice of the invention, it is of course
possible to use a curing agent for curing the epoxy
resin. Usable epoxy resin curing agents are those
epoxy curing agents that are commonly used. Such
curing agents include, but are not limited to, amines,
such as triethylenetetramine, tetraethylenepentamine,
diethylaminopropylamine, N-aminoethylpiperazine,
m-xylylenediamine, m-phenylenediamine, diaminodiphenyl-
methane, diaminodiphenyl sulfone, isophoronediamine and
2,4,6-tris(dimethylaminomethyl)phenol; tertiary amine
salts; polyamide resins; imidazoles; dicyandiamides;
ketimines; boron trifluoride complexes; carboxylic acid
anhydrides, such as phthalic anhydride, hexahydrophtha-
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lic anhydride, tetrahydrophthalic anhydride, endo-
methylenetetrahydrophthalic anhydride, dodecylsuccinic
anhydride, pyromellitic anhydride and chlorendic an-
hydride; alcohols; phenols; carboxylic acids; and the
like compounds.
4ahen the curing agent mentioned above is used, its
amount to be employed may vary depending on the kind of
epoxy resin and the kind of curing agent. Recommend-
ably, the curing agent should be used in an amount
within the range of 0.1 to 300 parts (parts by weight;
hereinafter the same shall apply) per 100 parts of
component (B).
In the composition of the invention, it is prefer-
ably, for improving the strength of cured products, to
use, as component (C), a silicone compound containing a
functional group capable of reacting with the epoxy
group and a reactive silicon group within its molecule.
The functional group contained in said silicon
compound and capable of reacting with the epoxy group
more specifically includes, among others, primary,
secondary and tertiary amino groups; mercapto group;
epoxy group; and carboxyl group. As the reactive
silicon group, there may be mentioned the same reactive
silicon groups that have been mentioned in the descrip-
tion of the afore-mentioned component (A). From the
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easy handling and other viewpoints, alkoxysilyl groups
are preferred, however.
As typical examples of such silicon compound,
there may be mentioned amino-containing silanes, such
as y-aminopropyltrimethoxysilane, y-aminopropyltri-
ethoxysilane, y-aminopropylmethyldimethoxysilane,
y-(2-aminoethyl)aminopropyltrimethoxysilane, y-(2-
aminoethyl)aminopropylmethyldimeth,oxysilane, y-(2-
aminoethyl)aminogropyltriethoxysilane, y-ureidopropyl-
triethoxysilane, N-~-(N-vinylbenzylaminoethyl)-y-amino-
propyltrimethoxysilane and y-anilinopropyltrimethoxy-
silane; mercapto-containing silanes, such as y-mercapto-
propyltrimethoxysilane, y-mercaptopropyltriethoxy-
silane, y-mercaptopropylmethyldimethoxysilane and
y-mercaptopropylmethyldiethoxysilane; epoxy bond-
containing silanes, such as y-glyeidoxypropyltri-
methoxysilane, y-glycidoxypropylmethyldimethoxysilane,
y-glycidoxypropyltriethoxysilane and ~-(3,4-epoxy-
cyclohexyl)ethyltrimethoxysilane; and carboxysilanes,
such as ~-carboxyethyltriethoxysilane, S-carboxy-
ethylphenylbis(2-methoxyethoxy)silane and N-~-(N-carb-
oxymethylaminoethyl)-y-aminopropyltrimethoxysilane.
These silicon compounds may be used either singly or in
combination in the form of a mixture of two or more of
them.
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It is preferred that the ratio between component
(A) and component (B) to be used in the composition of
the invention be (A)/(B)=100/1 to 1/100 by weight.
When the ratio (A)/(B) is below 1/100, the impact
strength and toughness of cured epoxy resin products
can hardly be improved effectively. When the ratio
(A)/(B) exceeds 100/1, the strength of cured
oxypropylene polymers becomes insufficient. The
preferred ratio between component (A) and component (B)
may vary depending on the use of the curable resin
composition and other factors and therefore cannot be
specified without reserve. For instance, for improving
the impact resistance, flexibility, toughness, peel
strength and other characterisitics of cured epoxy
resins, the component (A) should recommendably be used
in an amount of 1 to 100 parts, preferably 5 to 100
parts, per 100 parts of component (B). For improving
the strength of cured products from a reactive silicon
group-containing oxypropylene polymer, which is the
component (A), it is recommendable that the component
(B) be used in an amount of 1 to 200 parts, preferably
to 100 parts, per 100 parts of component (A).
The above-mentioned silicon compound (component
(c)) is used preferably in an amount such that the
weight ratio relative to components (A) and (B) falls
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within the range of ((A) + (B))/(C) - 100/0.1 to
100/20, more preferably ((A) + (B))/(C) - 100/0.2 to
100/10.
The method of preparing the curable composition of
the invention is not particularly limited but any
conventional method can be employed: for example, the
components mentioned above are combined and kneaded up
in a mixer, roll or kneader at ambient temperature or
under heating, or the components are dissolved in a
small amount of an appropriate solvent for attaining
admixing. Furthermore, it is also possible to prepare
one-can or two-can formulas by appropriately combining
those components.
The curable resin composition of the invention may
contain a silanol condensing catalyst (curing cata-
lyst). When a siianol condensing catalyst is used, it
may be selected from a wide variety of known ones. As
typical examples thereof, there may be mentioned such
silanol condensing catalysts as titanate esters, such
as tetrabutyl titanate and tetrapropyl titanate; tin
carboxylate salts, such as dibutyltin dilaurate,
dibutyltin maleate, dibutyltin diacetate, tin octanoate
and tin naphthenate; reaction products from dibutyltin
oxide and phthalate esters; dibutyltin diacetylaceto-
nate; organic aluminum compounds, such as aluminum
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trisacetyl-acetonate, aluminum tris(ethyl acetoacetate)
and diisopropoxyaluminum ethyl acetoacetate; chelate
compounds such as zirconium tetracetylaeetonate and
titanium tetracetylacetonate; lead octanoate; amine
compounds, such as butylamine, octylamine dibutyl-
amine, monoethanolamine, diethanolamine, triethanol-
amine, diethylenetriamine, triethylenetetramine,
oleylamine, cyclohexylamine, benzylamine, diethylamino-
propylamine, xylylenediamine, triethylenediamine,
guanidine, diphenylguanidine, 2,4,6-tris(dimethylamino-
methyl)phenol, morpholine, N-methylmorpholine, 2-ethyl-
4-methylimidazole and 1,8-diazabicycloE5.4.0]undecene-7
(DBU), and salts of such amine compounds with carboxy-
lic acids and so forth; low molecular weight polyamide
resins obtained from an excess of a polyamine and a
polybasic acid; reaction products from an excess of a
polyamine and an epoxy compound; amino-containing
silane coupling agents, such as Y-aminopropyltrimethoxy-
silane and N-(ø-aminoethyl)aminopropylmethyldimethoxy-
silane; and other known silanol condensing catalysts,
such as acid catalysts and basic catalysts. These
catalysts may be used either singly or in combination
in the form of a mixture of two or more of them.
These silanol condensing catalysts are used
preferably in an amount of about 0.1 to 20 parts, more
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preferably about 1 to 10 parts, per 100 parts of the
oxypropylene polymer. When the amount of the silanol
condensing catalyst is too small as compared with the
oxypropylene polymer, the rate of reaction may be slow
in certain instances and the curing reaction can hardly
proceed to a satisfactory extent in some instances. On
the other hand, if the amount of the silanol condensing
catalyst is too large relative to the oxypropylene
polymer, local heat generation and/or foaming may occur
during curing, unfavorably making it difficult to
obtain good cured products.
The curable resin composition of the invention may
be modified by incorporating thereinto various fillers.
Usable as the fillers are reinforcing fillers such as
fumed silica, precipitated silica, silicic anhydride,
hydrous silicic acid and carbon black; fillers such as
calcium carbonate, magnesium carbonate, diatomaceous
earth, calcined clay, clay, talc, titanium oxide,
bentonite, organic bentonite, ferric oxide, zinc oxide,
active zinc white, and "Shirasu" balloons; and fibrous
fillers such as asbestos, glass fibers and filaments.
For obtaining cured compositions affording high
strength using such fillers, a filler selected from
among fumed silica, precipitated silica, anhydrous
silicic acid, hydrous silicic acid, carbon black,
*Trade mark
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surface-treated finely divided calcium carbonate,
calcined clay, clay, active zinc white and the like is
used in the main in an amount within the range of 1 to
100 parts per 100 parts of the reactive silicon group-
containing oxypropylene polymer to give favorable
results. For obtaining cured compositions affording
low strength and high elongation, a filler selected
from among titanium oxide, calcium carbonate, magnesium
carbonate, talc, ferric oxide, zinc oxide,"shirasu"
balloons and the like is used in the main in an amount
within the range of 5 to 200 parts per 100 parts of the
reactive silicon group-containing oxypropylene polymer
to give favorable results. Of course, these ffillers
may be used either alone or in combination as a mixture
of two or more of them .
In using the reactive silicon group-containing
oxypropylene polymer in accordance with the invention,
a plasticizer may be used more effectively in combina-
tion with the filler since the use thereof may provide
the cured products with an increased elongation and/or
allow incorporation of fillers in large amounts. This
plasticizer is any one in common and general use.
Thus, for instance, phthalate esters, such as dioctyl
phthalate, dibutyl phthalate and butyl benzyl phtha-
late; aliphatic dibasic acid esters, such as dioctyl
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adipate, isodecyl succinate and dibutyl sebacate;
glycol esters, such as diethylene glycol dibenzoate and
pentaerythritol esters; aliphatic esters, such as butyl
oleate and methyl acetylricinoleate; phosphate esters,
such as tricresyl phosphate, trioctyl phosphate and
octyl diphenyl phosphate; epoxy plasticizers, such as
epoxidized soybean oil, and benzyl epoxystearate;
polyester plasticizers, such as polyesters from a
dibasic acid and a dihydric alcohol; polyethers, such
as polypropylene glycol and derivatives thereof;
polystyrenes, such as poly-cx-methylstyrene and poly-
styrene; polybutadiene, butadiene-acrylonitrile copo-
lymer, polychloroprene, polyisoprene, polybutene,
chlorinated paraffin, and so forth may be used either
singly or in combination in the form of a mixture of
two or more of them, as desired. Favorable results are
obtained when the plasticizes is used in an amount
within the range of 0 to 100 parts per 100 parts of the
reactive silicon group-containing oxypropylene polymer.
In using the curable resin composition of the
invention, various additives, such as adhesion impro-
vers, physical property modifiers, storage stability
improvers, antioxidants, ultraviolet absorbers, metal
inactivators, antiozonants, light stabilizers, amine
type radical chain inhibitors, phosphorus-containing
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peroxide decomposing agents, lubricants, pigments,
blowing agents, etc., may be added to said composition
as necessary each in an appropriate amount.
The curable composition of the invention is
curable at a temperature as low as room temperature.
It is also possible to cause rapid curing at a high
temperature of about 100 to 150°C. Therefore, said
composition can be subjected to curing within a wide
temperature_range from such low temperature to such
high temperature depending on the purpose. Parti-
cularly when an epoxy resin/epoxy resin curing agent
combination capable of curing at room temperature is
selected, the curable composition of the invention will
produce an interesting feature iri that said composition
gives high-strength cured products after room tempera-
ture curing. Furthermore, when a liquid type epoxy
resin is used, another feature will be produced that
solvent-free curable compositions can readily be
prepared.
The method of molding the curable resin composi-
tion of the invention is not critical. However, when
the amount of the epoxy resin is greater than that of
the reactive silicon group-containing oxypropylene
polymer, those methods that are generally used for
epoxy resin molding, for example compression molding,
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transfer molding and injection molding, are preferred
and, when molded by such methods, said composition
gives moldings, copper-clad laminates, reinforced wood
products and other laminated moldings improved in
impact resistance, flexibility, toughness and so on.
In addition, when it is formulated as mentioned above,
the composition may also be, suitably used as an adhe-
sive improved in peel strength, a foaming material
improved in flexibility, a binder for fiber boards and
particle boards, a paint, a binder for shell molds, a
binder for brake linings, a binder for abrasives, a
composite material prepared by combining with glass
fiber or carbon fiber, and so on.
On the other hand, when the amount of the reactive
silicon group-containing oxypropylene polymer is
greater than that of the epoxy resin; those molding
methods that are generally used in molding solid
rubbers such as natural rubber or in molding rubber-
like liquid polymers such as polyurethanes are prefer-
red and these molding methods give shaped rubber
articles, rubber-like foamed products and so on im-
proved in strength etc. When the amount of the reac-
tive silicon group-containing oxypropylene polymer is
greater than that of the epoxy resin, the composition
may also be suitably used as a rubber-type adhesive, a
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sealant, a sticking agent, or the like.
For further illustrating the invention, the
following examples are given.
Synthesis Example 1
A flask equipped with a stirrer was charged with
220 g (0.0447 equivalent) of polyoxypropylene triol
having a number average molecular weight of 15,000
(Mw/Mn = 1.38, viscosity = 89 poises) and 0.02 g of
dibutyltin dilaurate and, in a nitrogen atmosphere,
8.45 g (0.0447 equivalent) of y-isocyanatopropyl-
methyldimethoxysilane was added dropwise at room
temperature. After completion of the dropping, the
reaction was conducted at 75°C for 1.5 hours. IR
spectrum measurement was performed and, after confir-
oration of the disappearance of the NCO absorption at
about 2280 cm 1 and of the formation of a C=O absorption
at about 1730 cm 1, the reaction was discontinued. A
colorless and transparent polymer (2i3 g) was obtained.
Synthesis Example 2
A 1.5-liter pressure-resistant glass reaction
vessel was charged with 401 g (0.081 equivalent) of
polyoxypropylene triol having a molecular weight of
15,000 (Mw/Mn = 1.38, viscosity = 89 poises) and the
contents were placed in a nitrogen atmosphere.
At 137°C, 19.1 g (0.099 equivalent) of a 28$
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solution of sodium methoxide in methanol was added
dropwise from a dropping funnel, then the reaction was
conducted for 5 hours and thereafter the reaction
mixture was placed under reduced pressure for volatile
matter removal. Again in a nitrogen atmosphere, 9.0 g
(0.118 equivalent) of allyl chloride was added drop-
wise, the reaction was conducted for 1.5 hours and then
the allylation was further carried out using 5.6 g
(0.029 equivalent) of a 28% solution of sodium methox-
ide in methanol and 2.? g (0.035 equivalent) of allyl
chloride.
The reaction product was dissolved in hexane and
subjected to adsorption treatment with aluminum sili-
cate. The subsequent removal of the hexane under
reduced pressure gave 311 g of a yellow and transparent
polymer (viscosity = 68 poises).
A pressure-resistant glass reaction vessel was
charged with 270 g (0.065 equivalent) of this polymer
and the contents were placed in a nitrogen atmosphere.
A chloroplatinic acid catalyst solution (prepared by
dissolving 25 g of H2PtC16~6H20 in 500 g of isopropyl
alcohol; 0.075 ml) was added and the mixture was
stirred for 30 minutes. Dimethoxymethylsilane (6.24 g,
0.059 equivalent) was added from a dropping funnel and
the reaction was conducted at 90°C for 4 hours. The
CA 02313359 2000-07-18
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subsequent volatile matter removal gave 260 g of a
yellow and transparent polymer.
Comparative Synthesis Example 1
A pressure-resistant reaction vessel equipped with
a stirrer was charged with 800 g of polypropylene oxide
having a number average molecular weight of 8,000 as
obtained by subjecting 90 parts of polypropylene glycol
(number average molecular weight = 2,500) and 10 parts
of polypropylene triol (number average molecular weight
- 3,000) (starting materials) to molecular weight
jumping reaction using methylene chloride and then
capping the molecular chain terminals with allyl
chloride to thereby introduce aryl ether groups into
99~ of all terminals. Then, 20 g of methyldimethoxy-
silane was added to the vessel. After further addition
of 0.40 ml of a chloroplatinic acid catalyst solution
(prepared by dissolving 8.9 g of H2PtC16~6H20 in 18 ml
of isopropyl alcohol and 160 ml of tetrahydrofuran),
the reaction was conducted at 80°C for 6 hours.
The silicon hydride group remaining in the reac-
tion mixture was assayed by IR spectrometry and found
to be little. As a result of silicon group assay by
the NMR method, the product was found to be polypro-
pylene oxide containing, terminally to the molecule
thereof, about 1.75 groups of the formula
CA 02313359 2000-07-18
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C H 3
1
( C H 3 O ) 2 S i C H 2 C H 2 C H 2 O -
per molecule.
The viscosity of each of the polymers obtained in
Synthesis Examples 1 and 2 and Comparative Synthesis
Example 1 was determined at 23°C using a type B visco-
meter (BM type rotar No. 4, 12 rpm). Each polymer was
also analyzed for number average molecular weight (Mn)
and molecular weight distribution (MwlMn) by GPC. The
GPC was performed at an oven temperature of 40°C using
a column packed with a polystyrene gel (Tosoh Corpora-
tion) and tetrahydrofuran as the eluent. The results
are shown in Table 1.
Table 1
Viscosity Number average Molecular weight
Polymer (Poises) molecular weight distribution
(Mn) (Mw/Mn)
Synthesis
Example 1 150 1.7 x 104 1.4
Synthesis
Example 2 88 1.8 x 104 1.5
Comparative
Synthesis 240 1.5 x 104 2.3
Example 1
Examples 1 and 2 and Comparative Example 1
CA 02313359 2000-07-18
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One hundred (100) parts of each of
the polymers obtained in Synthesis Examples 1 and 2 and
Comparative Synthesis Example 1 was thoroughly kneaded
with 50 parts of Epikote 828 (bisphenol A type epoxy
resin produced by Yuka Shell Epoxy), 1 part of Nocrac*
SP (monophenolic antioxidant produced by Ouchi Shinko
Ragaku Rogyo), 5 parts of 2,4,6-tris(dimethylamino-
methyl)phenol (DMP-30), 1 part of N-~-(aminoethyl)-Y-
aminopropyltrimethoxysilane, 1 part of #918 (organotin
compound produced by Sankyo Yuki Gosei) and 0.4 part of
water. Among the compositions thus obtained, the
compositions of Examples 1 and 2 (in which the polymers
of Synthesis Examples 1 and 2 were used, respectively)
were lower in viscosity and easier to hand than the
composition of Comparative Example 1 (in which the
polymer of Comparative Synthesis Example 1 was used).
The compositions obtained were evaluated as
adhesives in the following manner.
For tensile shear strength measurement, test
samples were prepared according to JIS K 6850 using JIS
H 4000 aluminum plates A-1050P (test pieces 100 x 25 x
2 mm in size) and sticking two plates together with
each composition applied with a spatula, under manual
pressure.
For T-peel bonding strength evaluation, a T peel
*Trade mark
CA 02313359 2000-07-18
a~
- 28 -
test was performed according to JIS K 6854. JIS H 4000
aluminum plates A-1050P (test pieces 200 x 25 x 0.1 mm
in size) were used. Each composition mentioned above
was applied to a thickness of about 0.5 mm and, after
contacting, pressure was applied five times using a 5
kg hand roller and avoiding going and returning in the
lengthwise direction.
These adhesion test samples were cured at 23°C for
2 days and further at 50°C for 3 days and then sub-
jected to tensile testing. The rate of pulling was
adjusted to 50 mm/min for tensile shear testing and 200
mm/min for T peel testing. The results are shown in
Table 2.
Table 2
Example 1 Example 2 Comparative
Example 1
Polymer used Synthesis Synthesis Comparative
Example 1 Example 2 Synthesis
Example 1
Tensile shear
strength (kg/cm2) 78 76 78
T-peel strength 12 12 13
(kg/25 mm)
Examples 3 and 4 and Com arative Exam le 2
The compositions prepared in Examples 1 and 2 and
Comparative Example 1 were each spread to give a sheet
CA 02313359 2000-07-18
_ 2g _
having a thickness of 2 mm and cured at 23°C for 2 days
and further at 50°C for 3 days. Small pieces (1 cm x 1
cm) were cut out from these sheet-like cured products,
weighed, then immersed in 10 ml of 10~ aqueous acetic
acid solution and stored at 50°C.
After 14 days, the cured product pieces were taken
out and their surfaces were observed. The results are
shown in Table 3. In the table,,o means no change and
x means surface dissolution.
Table 3
Polymer used Surface condition of
cured product piece
Example 3 Synthesis Example 1 0
Example 4 Synthesis Example 2 0
Comparative Comparative
Example 2 Synthesis Example 1
The surface of the pieces of Comparative Example 2
was sticky and had been dissolved. On the contrary,
the pieces of Examples 3 and 4 showed little changes.
Therefore, it was found that the acid resistance had
been markedly improved by the present invention.
INDUSTRIAL APPLICABILITY
The reactive silicon group-containing oxypropylene
polymer to be used as component (A) in the curable resin
CA 02313359 2000-07-18
..
- 30 -
composition of the invention has a narrow molecular
weight distribution despite of its high number average
molecular weight. Therefore, before curing, the
composition of the invention is lower in viscosity and
easier to handle than compositions containing the
conventional reactive silicon group-containing oxypro-
pylene polymers having the same molecular weight but
showing a broader molecular weight distribution.
The low viscosity before curing as mentioned above
not only improves the processability but also enables
incorporation of a large amount of filler to give an
excellent room temperature curable composition.
After curing, the crosslinking network becomes
uniform and the cured products show good rubber-Iike
elastic behaviors, for example imgroved elongation
characteristics. Thus, when the composition of the
invention is used as an adhesive, good bonding
strengths are developed.
Furthermore, the chemical resistance, in parti-
cular acid resistance, is improved to an unexpectedly
great extent. The solvent resistance and water resis-
tance are also good.
As mentioned above, the curable resin composition
of the invention is of very high practical value.
