Note: Descriptions are shown in the official language in which they were submitted.
~12 ~!~37
This invention relates to siloxane-modified epoxy
resin compositions which contain an epoxy, methacryl, or amino
organofunctional alkoxysilicon compound and have improved
resistance to degradation by moisture and boiling water.
As described in United States Patent No. 3,154,597,
siloxane-modified epoxy resins which have both the excellent
chemical resistance of epoxy resins and the excellent heat
resistance of siloxane resins are known. One drawback of the
siloxane-modified epoxy resins is the poor resistance of the
cured compositions to degradation by boiling water and
moisture. For example, when siloxane-modified epoxy resins are
cured using conventional curing agents for epoxy resins,
especially polyhydric carboxylic acids or their anhydrides, the
electrical resistance and adhesion to inorganic substrates
decreases significantly when the composition is treated with
boiling water.
One of the purposes of the present invention then is
to improve the resistance to degradation by water of electrical
properties and adhesion of cured siloxane-modified epoxy resin
compositions.
A companion application by the same inventor with the
same filing date and assigned to the same assignee describes
siloxane-modified epoxy resin compositions with improved
resistance to degradation by boiling water and moisture. In
addition to the siloxane-modified epoxy resin and curing agent,
the compositions contain an organopolysiloxane which has at
least one alkoxy radical bound to silicon.
It has been found that the addition of an epoxy,
methacryl or amino organofunctional alkoxysilicon compound to
~2~L~37
compositions containing siloxane-modified epoxy resins and
curing agent improves the resistance to moisture degradation in
the cured compositions. This invention relates to a
siloxane-modified epoxy resin composition consisting
essentially of (A) 100 parts by weight of a siloxane-modified
epoxy resin prepared by reacting (1) 5 to 70 parts by weight of
an alkylphenylpolysiloxane of the general unit formula
RaSiXbO4-a-b
wherein R is selected from the group consisting of alkyl
radicals and phenyl radicals such that the ratio of alkyl
radicals to phenyl radicals in the alkylphenylpolysiloxane is
0.3 to 3.0, X is an alkoxy radical or a hydroxyl radical, a is
0.9 to 1.8 and b is 0.01 to 2 with (2) 95 to 30 parts by weight
of an epoxy resin having at least two epoxy groups per
molecule, (B) 0.01 to 100 parts by weight of an organosilicon
compound having attached to silicon an alkoxy radical and a
monovalent organic radical containing a functional group
selected from the group consisting of an epoxy group, a
methacryl group and an amino group and (C) a curing agent for
(A).
The siloxane-modified epoxy resin (A) employed in this
invention is prepared by reacting (1) an
alkylphenylpolysiloxane with (2) an epoxy resin.
The alkylphenylpolysiloxanes employed in the
preparation of resin (A) must have functional groups which are
capable of reacting with the functional groups of the epoxy
resin. Suitable alkylphenylpolysiloxanes then must have
hydroxyl radicals or alkoxy radicals which are bound to silicon
~2~37
atoms. The preferred alkylphenylpolysiloxanes have 0.01 to 2
of these functional groups per silicon atom in the siloxane.
The organic radicals bound to the silicon atoms of the
alkylphenylpolysiloxanes are alkyl radicals and phenyl
radicals. Suitable alkyl radicals include the methyl, ethyl,
propyl, butyl and octadecyl radicals. It is important that the
ratio of alkyl radicals to phenyl radicals in the polysiloxane
be in the range of 0.3 to 3Ø If the molar ratio of alkyl
radicals to phenyl radicals in the polysiloxane is too low, the
siloxane-modified epoxy resin prepared from that polysiloxane
is undesirably brittle. On the other hand, if the ratio is too
high, it is difficult to carry out the modification reaction
with the epoxy resin.
In addition, the average number of organic radicals
per silicon atom for the polysiloxane should be in the range of
0.9 to 1.8. Siloxane-modified epoxy resin prepared from a
polysiloxane containing less than 0.9 organic radicals per
silicon atom is too brittle while resin prepared from a
polysiloxane containing greater than 1.8 organic radicals per
silicon atom is too soft.
Suitable alkylphenylpolysiloxanes can be produced by
conventional methods. For example, the
alkylphenylpolysiloxanes can be produced by the co-hydrolysis
and co-condensation of the corresponding halo or alkoxy
silanes.
The epoxy resins which are reacted with the
alkylphenylpolysiloxanes are common epoxy resins having at
least two epoxy groups per molecule. Examples of these epoxy
resins are as follows: polyglycidyl esters, polyglycidyl
ethers which are obtained by base catalyzed reaction of
~2~1937
epichlorohydrin with aromatic polyhydric phenols such as
bisphenol A, bisphenol F, halogenated bisphenol A, catechol,
resorcinol, methylresorcinol and novalak resins or aliphatic
polyhydric alcohols such as glycerol, ethylene glycol and
neopentyl glycol and epoxidized polyolefins such as epoxidized
polybutadienes and epoxidized soybean oil. The preferred epoxy
resins for the present invention are the polydiglycidyl ethers
of bisphenol A with a molecular weight of 340 to 6000. Such
epoxy resins are commercially available as Epon~ 828, Epon~
1001 and Epon~ 1004 from the Shell Chemical Company.
The siloxane-modified epoxy resins can be produced by
reacting the above-described alkylphenylpolysiloxanes with the
epoxy resins according to the methods specified in United
States Patent No. 3,154,597, Japanese Patent No. Sho
29[1954]-8695, and Japanese Patent No. Sho 29[1954]-8697. For
example, the alkylphenylpolysiloxane can be reacted with the
epoxy resin by heating the combined materials at about 120 to
210C. If desirable, a solvent such as toluene, xylene, acetic
acid esters and various ketones can be employed to reduce the
viscosity of the reaction composition. In addition, catalysts
such as alkyl titanates, p-toluenesulfonic acid and organic
carboxylic acids can be employed to facilitate the reaction.
Generally, 5 to 70 parts by weight of the
alkylphenylpolysiloxane can be reacted with 95 to 5 parts by
weight of the epoxy resin to prepare siloxane-~odified epoxy
resins useful in the present invention. If a lower amount of
alkylphenylpolysiloxane is employed, the heat resistance of the
resulting resin is not significantly improved, while if higher
amounts are employed, the mechanical strength of the cured
composition is reduced. Preferably, 15 to 50 parts by weight
~2`~937
of the alkylphenylpolysiloxane is reacted with 85 to 50 parts
by weight of the epoxy resin.
The organosilicon compound (B) employed in the
compositions of this invention is an important constituent
which imparts moisture and boiling water resistance to the
cured siloxane-modified epoxy resin. Cured compositions of
this invention retain their electrical properties and adhesion
to inorganic substrates even after exposure to boiling water
for extended periods. Suitable organosilicon compounds (B)
have at least one alkoxy radical attached to silicon and at
least one monovalent functional organic radical attached to
silicon. The organosilicon compounds include organofunctional
silanes of the general formula
Zm~s i~Yn
R 4-m-n
wherein Z is a monovalent organic radical containing a
functional group selected from the group consisting of an epoxy
group, a methacryl group and an amine group, Y is a lower
alkoxy radical, R' is a hydrogen atom or a monovalent
hydrocarbon radical, m and n are integers of 1 to 3 and m + n
does not exceed 4.
Representative of Z are organic radicals in which an
epoxy group, methacryl group or amino group is bound to a
divalent organic radical such as methylene, ethylene,
propylene, phenylene, hydroxylated hydrocarbon radicals,
chloroethylene, fluoroethylene and
--CH20CH2CH2CH2 ' --CH2CH20CH2CH2 ~
C,H3
-cH2cH2ocHcH2-~ and -CH20CH2CH20CH2CH2-
~2 '~37
Examples of lower alkoxy radicals include methoxy,
ethoxy, propoxy, isopropoxy and butoxy.
Examples of suitable monovalent hydrocarbon radicals
include methyl, ethyl, propyl, octyl, cyclohexyl, phenyl and
vinyl.
It should be understood that suitable organosilicon
compounds (B) also include both partially hydrolyzed products
of the above organofunctional silanes and straight chain or
cyclic copolymers of the above organofunctional silanes with
io other nonfunctional organosilanes.
Examples of suitable organosilicon compounds (B)
include
H2C~-~HCH2CH2si(OcH3)3
H2C~-~HCH2cH27i(OcH3)2
O CH3
H2C--~CHO(CH2)3si(OcH3)3
H2C-CHCH20(cH2)3si(ocH3)3
O
H2C-~ Ho(cH2)3si(oc2H5)2
IOCH3
H2c\-cHcH2o(cH2)3lsi(cH2)3ocH2c\H ~CH2,
o OCH3 O
0~
~ -CH2CH2si(Oc2H5)3
1~:24~37
! , CH3 ~ OCH
CH3 2 (CH2)3ocH2c\H-/cH2 2
O
oC2H5 / CH3 oC2H5
H2C~-CHCH20(CH2)3SiO ~ iO- Si(CH2)30cH2c~H~cH2
C2H5 CH3 O C2H5
H2C=C C-O--(CH2)3Si(OC2H5)3,
CH3 0
H2C=C C-O-(CH2)3Si(OcH3)3
CH3 0
H2C=C--C-o - (cH2)3si(oc2H5)2~
- .
CH3 CH3
CH3 / oCH3 \ CH3
H2C=C, C--O(CH2) 3siotsio tSi (CH2)30--C--C=CH2
CH3 CH3 OCH3 4 CH3 0 CH3
H2N--(CH2)3si(oc2H5)3~
H2NCH2CH2NH(CH2)3si(OcH3)3
H2N-(CHz)3Si(Oc2H5)2
CH3
oCH3 OCH3
H2N-(CH2)3 S,io Si-(CE~2)3NH2
OCH3 OCH3
and
/ CH3 \ / 0CH3 \ C,H3
H2N-(CH2)3t SiO~ SiOt si-(cH2)3-~H2-
CH3 2 OCH3 4 CH3
9~7
These compounds can be used alone or two or more compounds can
be used in combination.
Generally, the amount of (B) employed is in the range
of 0.01 to 100 parts by weight (B) to 100 parts by weight of
the siloxane-modified epoxy resin (A). If the amount of (B)
used is too low, satisfactory adhesion with resistance to
boiling water is not obtained. If it is too high, the cured
composition becomes brittle. Preferably, the amount of (B)
employed is in the range of 0.5 to 50 parts by weight per 100
parts by weight (A).
Curing agent (C) is employed in the compositions of
this invention to cure the siloxane-modified epoxy resin.
Curing -agents which are commonly used for epoxy resins can be
used without any modifications. Conventional curing agents for
epoxy resins include organic compounds having amino groups,
carboxyl groups, carboxylic anhydride groups, hydroxyl groups,
-SH groups, -NCO groups, -NCS groups or CONH- groups,
organometallic compounds, Lewis acids, organic mineral acid
esters, or titanium, zinc, boron or aluminum compounds
containing organic groups. In addition, other acidic or basic
compounds are also applicable.
Examples of these compounds are as follows: aliphatic
polyamines such as ethylenediamine, diethylenetriamine,
triethylenetetramine, dipropylenetriamine,
dimethylaminopropylamine, diethylaminopropylamine and
cyclohexylaminopropylamine, aliphatic hydroxylmonoamines such
as monoethanolamine, diethanolamine, propanolamine and
N-methylethanolamine, aliphatic hydroxyl-polyamines such as
aminoethylethanolamine, monohydroxyethyldiethylenetriamine,
3~
bishydroxyethyldiethylenetriamine, and N-(2-hydroxy-
propyl)ethylenediamine, aromatic amines such as aniline,
toluidine, ethylaniline, xylidine, benzidine, 4,4'-diamino-
diphenylmethane, 2,4,6-tri(dimethylaminomethyl)phenol,
2,2-bis(4-aminophenyl)propane, 4,4'-diaminodiphenyl ether,
4,4'-diaminodiphenyl sulfone, 4,4'-diaminobenzophenone,
2,2'-dimethyl-4,4'-diaminodiphenylmethane, 2,4'-diamino-
biphenylr 3,3'-dimethyl-4,4'-diaminobiphenyl and
3,3'-dimethoxy-4,4'-diaminobiphenyl, aliphatic amines having a
cyclic structure such as piperidine, N-aminoethylpiperidine and
triethylenediamine, polyhydric carboxylic acids such as
phthalic acid, maleic acid, trimellitic acid, pyromellitic
acid, tetrahydrophthalic acid, hexahydrophthalic acid,
tetrachlorophthalic acid, dodecenyl- succinic acid,
endomethylenephthalic acid, methylendomethylenephthalic acid,
hexachloromethylene tetrahydrophthalic acid and chloromaleic
acid and their acid anhydrides. Other examples of
nitrogen-containing curing agents are dicyandiamide, guanidine,
NCO-group-containing polyurethane resin prepolymer, and urea
resin primary condensation product. In addition, titanium,
zinc, boron and aluminum compounds containing organic groups,
i.e. tetrabutyl titanate, dibutyltin dilaurate,
Cu[Al(C4H90)4]2, stannous octoate, zinc octoate, cobalt
naphtholate, may also be applicable. In particular, polyhydric
carboxylic acids or their acid anhydrides are preferred.
The amount of curing agent (C) employed in the
compositions of the present invention varies significantly
depending upon the type of curing agent selected. Generally,
the amount of curing agent to be employed, can be calculated
roughly as one equivalent curing agent based on the groups
1124937
subject to reaction in the curing agent per equivalent
siloxane-modified epoxy resin based on the groups subject to
reaction in the resin. However, the optimal amount of curing
agent may fluctuate considerably from this calculated
equivalent value. Therefore, the optimum amount of curing
agent for any particular composition is best determined by a
few initial experiments.
In addition to the essential constituents (A), (B) and
(C), various additives can be included in the compositions of
this invention. For example, additives such as inorganic
pigments, organic pigments, antimony oxide, silica, silica
powder, glass fiber, clay, mica, aluminum powder can be
included in the compositions. When the siloxane-modified epoxy
resins are produced, an organic solvent can be used as
mentioned previously. The siloxane-modified epoxy resins still
containing the above-mentioned organic solvent can be used in
the composition of this invention, or a fresh organic solvent
can be added.
The following examples are presented for illustrative
purposes and should not be construed as limiting the invention
set forth in the claims. Unless otherwise specified, "parts"
and "percent" as used in the following examples imply "parts by
weight" and "percent by weight", respectively.
Example 1
A polydiglycidyl ether of bisphenol A epoxy resin with
an epoxy equivalent weight of 450-550, Epon~ 1001 from Shell
Chemical Co. (112.5 parts), methylphenylpolysiloxane with a
molecular weight of approximately 1600 and an average
composition of (cH3)o.35(c6H5)o.7o(oH)o.28siol.335 (37 5
parts), 2-ethylhexanoic acid (2 parts) and ethylene glycol
~.~Z ~7
monoethyl ether acetate (100 parts) were placed in a 500 ml
four-necked flask which was equipped with a distilling tube, a
condenser, a stirring device and a thermometer. The mixture
was slowly heated to 150-155C. Water produced as a by-product
was distilled from the reaction system during the reaction.
Samples of the reaction mixture were occasionally removed and
placed on a glass plate. The reaction was continued until a
transparent film was obtained on the glass plate after
evaporating the solvent. The reaction time required was 8
hours. After a transparent film was obtained, the tempera-
ture was decreased to 120C and additional ethylene glycol
monoethyl ether acetate (50 parts) was added. As a result, a
siloxane-modified epoxy resin with a solids content of about 50
percent was obtained.
Five different compositions were prepared as shown in
Table I by mixing the above siloxane-modified epoxy resin (100
parts, solids content), trimellitic anhydride as a curing agent
(12 parts) and three different organosilicon compounds in
various amounts.
The resulting compositions were coated at a thickness
of approximately 50 ~ m on a degreased glass plate with the
dimensions 50 x 50 x 5 mm. The coating was baked at 150C for
60 minutes. The physical properties of the coatings were
determined before and after treating the coated plates with
boiling water for 30 hours under standard pressure.
For the determination of volume resistivity, the
compositions were coated at a thickness of approximately
100 ~m on aluminum test panels with the dimensions 100 x 100 x
0.3 mm. The coating was baked at 150C for 60 minutes. The
results of the checkerboard adhesion test and volume
~24~37
resistivity measurement are presented in Table I. The volume
resistivity measurement was conducted according to JIS-C-2122.
The checkerboard adhesion test consisted of cutting a grid of
lines in the coating to produce 100 squares (1 mm2) in an area
of 10 mm x 10 mm of the plate. Cellophane tape was applied to
the squares with pressure and then peeled off. The degree of
adhesion was expressed as the number of squares which remained
on the base plate out of the original 100 squares.
The results shown in Table I indicate that comparison
compositions without the organosilicon compound peeled away
spontaneously from the glass plate within one hour of boiling
in water. On the other hand, coatings prepared from
compositions with organosilicon compounds according to this
invention were found to be firmly adhered to the glass plate
even after boiling in water for 30 hours. Thus, the adhesion
was found to be resistant to boiling water.
Similarly, boiling water significantly reduced the
volume resistivity of coatings prepared from comparison
compositions without an organosilicon compound, while much less
effect was observed with coatings prepared from compositions
containing the organosilicon compounds according to this
invention.
Example 2
The epoxy resin employed in Example l, (105 parts),
methylphenylpolysiloxane with a molecular weight of
approximately 2300 and an average composition of
(CH3)0.83(C6H5)0.41(OH)o.25siol.2ss (45 parts), 2-ethylhexanoic
acid (2 parts) and ethylene glycol monoethyl ether acetate (100
parts) were placed in a 500 ml four-necked flask which was
equipped with a distilling tube, a condenser, a stirring device
~ 2
~124937
and a thermometer. The mixture was slowly heated to 150-155C.
Samples of the reaction mixture were occasionally taken and put
on a glass plate during the reaction. The reaction was
continued until a transparent film was obtained on the glass
plate after evaporating the solvent. After 9 hours, the
temperature was decreased to 120C. and additional ethylene
glycol monoethyl ether acetate (50 parts) was added. As a
result, a siloxane-modified epoxy resin with a solids content
of about 50 percent was obtained.
Three different types of compositions were prepared by
adding zero, 5 or 10 parts of 1,3-bis(3-aminopropyl)-1,1,3,3-
tetramethoxydisiloxane to a mixture of the above
siloxane-modified epoxy resin (100 parts based on solids),
hexahydrophthalic anhydride (24 parts) as a curing agent and
tin octoate (0.46 parts) as a reaction accelerator.
The compositions were coated on glass plates and
aluminum plates and cured by the same method as in Example 1.
The same tests as in Example 1 were conducted with respect to
the cured films. The results obtained are presented in Table
II.
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