Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Case
Background of the Invention
This invention relates to a phenolic resin composition having an epoxy
resin incorporated therein.
~ It is well known to incorporate epoxy resins into a novolac type
phenolic resin so as to make such phenolic resins flexible. It is also
well known to employ a novolac type phenolic resin as a hardener for epoxy
resins. In the former instance of the prior art, a phenollc resin
composition ls prepared by mixing a bisphenol type epoxy resin with a
novolac type phenolic resin, or prepared by adding an epoxy resin into
said phenolic resin during its reaction. However, when such a resin
composition ls cured by heat when used as a binder, effective crosslinking
is uncertain because epoxy groups present in said composition are poor in
reactivity. Thus in the past, molded articles excellent in heat
resistance could not be obtained because of low crosslinking density of
the composition.
After much investigation to overcome such drawbacks, the inventor has
found that a particular ratio of incorporation of a bisphenol type epoxy
resin into a solid phenolic resin improves the brittleness of the pheno~ic
resin itself, improves flexibility (improving impact resistance) thereof,
as well as retaining heat resis-tance thereof.
Summary of the Invention
The phenolic resin composition according to the present invention is
prepared by incorporating 3 to 20 parts by weight of a solid bisphenol
type epoxy resin and 0.5 to 10 parts by weight of a novolac type epoxy
5 resin into 100 parts by weight of a novolac or resole type solid phenolic
resin.
Description of Embodiments
The novolac type phenolic resin according to the present invention is
obtained by reacting phenols and aldehydes in the presence of catalysts
such as hydrochloric acid, sulfuric acid, oxalic acid and phosphoric acid,
employed either jointly or alone. A resole type phenolic resin according
to the present invention is obtained by reacting phenols and aldehydes in
the presence of catalysts such as hydroxides of alkali metals (sodium
hydroxide, potassium hydroxide, etc.), or of alkali earth metals (calcium
hydroxide, magnesium hydroxide, barium hydroxide, etc.), ammmonia and
amines, employed either jointly or alone.
Phenols employed in the present invention are such as phenol, cresol,
xylenol, resorcinol, para-ter-t-butylphenol, para-octylphenol,
para-nonylphenol, and para-phenylphenol, employed either jointly or
alone. Aldehydes employed in the present invention are such as
formaldehyde, para-formaldehyde, acetaldehyde, benzaldehyde and fulFural,
employed either jointly or alone.
The bisphenol type epoxy resin used in the present invention has an
epoxide equivalent of 170 to 4000, preferably 400 to 1500, and may or may
not contain a halogen atom. The novolac type epoxy resin used in the
present invention is selected from phenol novolac type, cresol novolac
type and halogenated epoxies.
Following are four embodiments of the method for preparing the
phenolic resin compositions oF the present invention:
(1) Method for preparing said composition first by adding a bisphenol type
and novolak type epoxy resin to a solid }~heno1ic resin, successive]y
adding or not adding hexamethylene tetramine (hereinafter called as
hexamine) thereto, followed by grinding the resulting product-mix.
~2) Method for preparing said composition by adding a bisphenol type epoxy
resin to a solid phenolic resin during its preparation process,
successively adding a novolac type epoxy resin, if necessary hexamine
too, and by grinding the resulting product-mix.
(3) Method for preparing said composition by mixing a solid phenolic
resin, a bisphenol type epoxy resin and novolac type epoxy resin, if
necessary hexamine too, and by grinding the resulting product-mix.
(4) Method for preparing said composition by adding a bisphellol type and a
novolac type epoxy resin, if necessary hexamine too, to a solid
phenolic resin in a mixing apparatus such as kneader, roll mill or
some other available mixers provided with heating, and by grinding the
resulting product-mix.
Hexamine employed in the above-mentioned methods is preferably 3 to 20
parts by weight to 100 parts by weight of novolac resin content in the
solid phenolic resin.
The ratio of incorporation of a bisphenol type epoxy resin is
preferably 3 to 20 parts by weiyht to 100 parts by weight of the solid
phenolic resi~. When the ratio of a bisphenol type epoxy resin is less
than 3 parts by weight, it is ineffective in enhancing flexibility. When
it is more than 20 parts by weight, it reduces heat resistance due to
decrease in crosslinking density. The ratio of incorporation of the
3~
novolac type epoxy resin ls preferably 0.5 to 10 parts
by welght, more preferably 0.5 - 5 par-ts by weight, to
100 par-ts of the solid phenollc resin. When said ratio
of the novolac type epoxy resin is less that 0.5 par-ts
by weight, it is ineffective in crosslinking as well
as in heat resistance. When it is more than 10 parts
by weight, it reduces its flexibility.
As for the pehnolic resin composition of the pre-
sent invention, adhesion of the phenolic resin is en-
hanced along with improved flexibility and impact
strength without reducing heat resistance, due -to good
flexibility of the bisphenol type ipoxy resin and the
good crosslinking effect of the novolac type epoxy resin.
The phenolic resin compositions of the present
inven-tion show excellent characteristics in applications
such as molding materials, grinding wheels, abrasives,
foundry resins, friction materials, and other organic
or inorganic binders.
The present invention is further explained by the
following nonlimitative examples, in which "parts"
indicates "par-ts by weight".
Example 1
To 100 parts of a novolac type phenolin resin, 10
parts of a bisphenol type epoxy resin (available under
trademark "EPIKOTE" 1004 by Shell Chemical Co.) was
added during preparation of the phenolic resin. To the
-thus obtained resin, 2 parts of a novolac -type epoxy
resin (available under serial number "ECN-1280" by Ciba
AG) and 10 parts by hexamine were added. The product-mix
was ground to powder composition. A specimen for abrasive
testing was prepared with the composi-tion of the inven-
tion exemplified in the following formula-tion by hot
pressing. Both bending and impact tests were run:
Formulation
Abrasive particle Altl2 100 parts
Said powder composition 15.0
Pyrite 10.0
Cryolite 10.0
Quick lime 1.5
Furfural 1.0
The formulated material was charged into a mold having the
dimensions: 15 (thickness) x 25 (width) x 100 (length) in mm., and
pressed at 160C under a pressure of 500Kg/cm2 for 15 minutes. The
molded article was baked (10 hours from ambient temperature to 170C1
and successfully 5 hours at 170C; 15 hours as total) and a specimen for
abrasive testing was prepared having a bulk density of 3.10. Tests were
run for bending strength at both ambient and elevated temperature
(250 C) and impact strength at ambient temperature.
The results were indicated in Table 1, in which excellent bending and
impact strength, respectively at ambient temperataure were shown.
Comparative Example 1
A powdered novolac type phenolic resin (10 parts of hexamine was
incorporated to 100 parts of said phenolic resin) was prepared, and tests
were run in the same manner as Example 1.
Comparative Exam~le 2
To 100 parts of a novolac type phenolic resin, 10 parts of a bisphenol
type epoxy resin (available under tradename "EPIKOTE" 1004 by Shell
Chemical Co.) was added during preparing said phenolic resin. To the
product 10 parts of hexamine was added and ground to a powdered phenolic
resin composition. Tests were run in the same manner as Example 1 with
the same formulation.
Table 1
ComparativeComparatlve
Example 1 Example 1Example 2
____ ~ _ __ _
Bending at ambient temp. 523 462 496
strength _ _ _ _ _ _ . _ ~. _
(Kg/c~) at elevated temp. 274 260 182
_ . ._
Impact stength (Kg/cm2) 1.7 1.2 1.5
Example 2
To 80 parts of a novolac type and 20 parts of a solid resole type
phenolic resin, 15 parts of a bisphenol type epoxy resin (available under
tradefl~m~ "EPIKOTE" 1001, by Shell Chemical Co.), 3 parts of a novolac
type epoxy resin (available under serial number "ECN-127~" by Ciba AG) and
8 parts of hexamine were added. The produc-t-mix was ground to form a
powdered composition. Tests for brake lining were run on specimens with
the composition of the invention exemplified in the following formulation:
Formulation:
Asbestos 6D 60 Parts
Said powder composition 20
Barium sulfate 10
Dusty cashew powder 10
The formulated material was charged into a mold having the
dimensions: 15 (thickness) x 25 (width) x 100 (length) in mm., and
pressed at 180C with 200Kg/cm2 for 15 minutes. The molded specimens
were baked (3 hours at 180C). Tests were run for bending strength and
friction characteristics (according to JIS Dk-4411) at both ambient and
elevated temperature.
The results were indicated in Fig. 2, in which an excellent bending
strength at ambient temperature and friction characteristics were shown.
Comparative Exanlple 3
1o 80 parts of a novolac type phenolic resin and 20 parts of a solid
resole type phenolic resin, 8 parts of hexamine was added. The
product-mix was ground to form a powdered composition. TPsts were run on
specimens prepared with this resin formulation as in the same manner as
Example 2.
Table ?
Comparative
Example 2Example 3
at amoient temp. 736 615
Bending strength __ __
(Kg/cm2)at elevated temp.433 411
__ at lOODC 2.2 0.39 2.3 0.35
150~C ~ ~ 2.3 0.39 2.5 0.31
Friction properties200 C _ 2.5 0.38 3.1 0.28
250C 5.4 0.39 8.7_ 0.28
300C _ 9.2 0.38 23.3 0.2a
(Note) V: Friction ratio (10 7cm3/K~-m)
~: Friction coefficient
