Note: Descriptions are shown in the official language in which they were submitted.
~ ~ ~, , . 3 ~?:J ~S
- 1 -
EPOXY RESIN LAMINATING VARNISH
AND LAMINATES PREPARED THEREFROM
The present invention pertains to a mixture of
a halogenated phenoxy resin and an advanced epoxy
resin, laminating varnishes containing same and
laminates prepared therefrom.
Electrical laminates are prepared by blending
minor amounts of a phenoxy resin with an advanced epoxy
resin, curing agent therefor and solvent3 if required.
The phenoxy resin provides flow control for the
composition during the laminating stage which invslves
pressure molding of la~ers of substrates impregnated
with the laminating varnish. This prevents the resin
from flowing out of the press or mold which prevents
resin poor areas in the resultant laminate. While the
phenoxy resins employed provide for good flow control
during molding or pressing of the impregnated
substrates, the resultant laminates exhibit a decrease
in one or more of their mechanical properties such as,
for example, glass transition temperature, moisture and
blister resistance and flame retardant properties.
34,618-F -1-
~3~39S
--2--
The present invention provides a method for
eliminating or decreasing the 105s in one or more of
the physical properties such as, for example, glass
transition temperature, moisture and blister resistance
and flame retardant properties by employing as the
phenoxy resin a halogenated phenoxy resin.
The present invention in one aspect pertains to
a composition which comprises (A) at least one phenoxy
resin and (B) at ;l~ast one advanced epoxy resin,
characterized in that said phenoxy resin is a nuclearly
halogenated phenoxy resin having a halogen content of
at least 5 percent by weight, said phenoxy resin being
present in an amount of from 0.5 to 50 , preferably
from 1 to 20, most preferably from 3 to 10 percent by
weight of the combined weight of components (A) and
(B); and said advance epoxy resin is a nuclearly
brominated advanced epoxy resin present in an amount o~
form 99.5 to 50, preferably from 99 to 80, most
preferably from 97 to 90 percent by weight of the
combined weight of component~ (A) and (B).
Another aspect of the present invention
pertains to a laminating varnish which comprises:
(A) the aforementioned composition;
(B) curing amount of at least one curing agent
for the advanced epoxy resin; and
(C) optionally one or more solvents.
Another aspect of the present invention
pertains to a substrate impregnated with the aforemen-
tioned laminating varnish.
34,618-F -2-
-
--3--
Still another aspect of the present invention
pertains to a laminate prepared from one or more of the
aforementioned impregnated substrates.
A further aspect of the present invention
pertains to an electrical laminate comprising at least
one electroconductive layer and one or more layers of
the aforementioned impregnated substrates.
Phenoxy resins are well known and are prepared
~y reacting a diglycidyl ether of a dihydric phenol
with a dihydric phenol in the presence of a suitable
catalyst in quantities which provide a phenolic
hydroxyl to epoxy ratio of from 0.9:1 to 1 1,
preferably from 0.92:1 to 0.99:1, most preferably from
0.95:1 to 0.98:1.
The halogenated phenoxy resins employed in the
present invention can be prepared as above employing
(a) an aromatic halogenated epoxy resin and a non-halo-
genated phenolic material, (b) a non-halogenated epoxy
resin and an aromatic halogenated phenolic material or
(c) an aromatic halogenated epoxy resin and an aromatic
halogenated phenolic material.
Suitable phenolic materials which can be
employed to prepare the aromatic halogenated phenoxy
resins which can be employed herein include, for
example, those represented by the following Formula-s I
3 and II:
34,618-F -3_
.
..
- ~3c~ S
--4--
0~
(R)4 ~ 0H
II. H0- ~ (A)n ~ OH
(R)4 (R)4
wherein A is a divalent hydrocarbyl group having from 1
to 20, preferably ~rom 2 to 10, most preferably from 3
to 5 carbon atoms,
O O O
., ,. ..
-S-, -S-S-, -S-, -S-, -0-, or -C-; each R is
zO independently ''
hydrogen, a hydrocarbyl group ~1aving from 1 to 6,
preferably from 1 to 4, most preferably from 1 to 2
carbon atom~ or a halogen, preferably bromine; and n
has a value of zero or 1. Particularly suitable
phenolic hydroxyl-containing materials include, for
example, tetrabromobisphenol ~, resorcinol, bisphenol
A, bisphenol S, and mixtures thereof.
3 Suitable epoxy resins which can be employed in
the preparation of the aromatic halogenated phenoxy
resins include, for example, those represented by the
following Formulas III and IV:
34,618~F _4_
" ' l3a:l3~3s
o~ c-)
o
oc ~
o o
O~ c~;
= ~ ~
~ ~r
o~y o
c~ ~
N O I -
X V- ~;
C~ .
H H
H
34 ,618-F _5~
:................... ~ .
` '`
.
\ ~
~31~95
--6--
wherein each A is independently a divalent hydrocarbyl
group having from 1 to 20, preferably from Z to 10,
most preferably from 3 to 5 carbon atoms,
O O O
-S-, -S-S-, -S-~ -S-, -O-, or -C-;
o
each R i5 independently hydrogen, a hydrocarbyl group
having from 1 to 6, preferably from 1 to 4, most
preferably from 1 to 2 carbon atoms or a halogen,
preferably bromine; R' is hydrogen or an alkyl group
having from 1 to 4 carbon atoms; n has a value of zero
or 1 and n' has an average value from zero to 10,
preferably frcm 0.1 to 7, most preferably from 0.1 to
3. Particularly suitable epoxy resins include, for
example, the diglycidyl ether of tetrabromobisphenol A,
the diglycidyl ether of bisphenol A, the diglycidyl
ether of bisphenol F, the diglycidyl ether of bisphenol
S, the diglycidyl ether of resorcinol, the diglycidyl
ether of bisphenol, and mixtures thereof.
The phenoxy resin employed herein should
contain a suffiaient number of aromatic halogen atoms
so as to provide the phenoxy resin with an aromatic
halogen content of at least 5, preferably from 15 to
50, most preferably from 20 to 40 percent by weight.
The phenolic halogenated phenoxy resins of the
present invention can be represented by the following
Formula V:
wherein A, ~, R' and n are as defined above, each Z is
independently a terminal group which is -OH or
34,618-F -6-
3~ ~ ~ 9
--7--
Z ~ (A)n ~ 0-CH2-C-CHz ~ (A) ~ z
(R)4 (R)4 " (R)4 (R)4
1( ;;
A
-OCH2-C C~2
R'
and n" has a value of at least 15, preferably from 30
to 100, most preferably from 40 to 70 with the proviso
that at least a suf`f.icient number of the R groups are a
halogen to pro~ide the aromatic halogenated phenoxy
resin with the required halogen content.
The advanced epoxy re~ins which can be employed
herein can be prepared by reacting a dihydric phenolic
material with a material containing an average of more
than one and preferably from 2 to 10, and most
preferably from 2 to 4 vicinal epoxy groups per
molecule in the presence of a suitable catalyst. In
their preparation? the ratio of phenolic hydroxyl
groups to epoxy groups is from 0.05:1 to 0.75:1,
preferably from 0.2:1 to 0.6:1, most pre~erably from
0.-3:1 to 0.4:1. These advanced epoxy resins can
contain aromatic halogen atoms or they can be free of
34,618-F -7
:
.
` ` .... ,.~,.. ` .. ` .. ` . 1 ` ~ . ' '
~3~
aromatic halogen atoms. For the preparation of
electrical laminates, they preferably contain aromatic
halogen atoms, preferably bromine atoms. Suitable
advanced epoxy resins which can be employed in
admixture with the halogenated phenoxy resins include,
for example, those represented by the Formulas III and
IV wherein A, R, R' and n are as defined above and n'
has a value from 1 to 10, preferably from 2 to 7, most
preferably ~rom 3 to 5. Particularly suitable advanced
epoxy resins include, for example, the diglycidyl ether
of bisphenol A advanced with tetrabromobisphenol A, the
diglycidyl ether of bisphenol A advanced with bisphenol
A, the diglycidyl ether of tetrabromobisphenol A
advanced with tetrabromobisphenol A, and mixtures
thereof. Each of these advanced epoxy resins have an
average n' value as illustrated in Formula IV within
the scope of the aforementioned range.
Suitable catalysts which can be employed to
prepare the aromatic halogenated phenoxy resins and the
advanced epoxy resins include, for example, quaternary
ammonium compounds, phoAphonium compounds, imidazoles,
phosphines, tertiary amines, inor~anic bases, mixtures
thereof and the like. Particularly suitable catalysts
include, for example, ethyltriphenylphosphonium
acetateacetic acid complex, ethyltriphenylphosphonium
bromide, benzyl dimethyl amine~ 2-methylimidazole,
triphenyl phosphine, potassium hydroxide-, and mixtures
3 thereof.
Suitable solvents which can be employed herein
include, for example, ketones, alcohols, glycol ethers,
aromatic hydrocarbons, and combinations thereof.
Particularly suitable solvents include, for example,
methyl ethyl ketone, methyl isobutyl ketone, propylene
34,618-F -8-
. ,;, . . . . . . .
` ~`` 1301
_9_
glycol methyl ether, ethylene glycol methyl ether,
methyl amyl ketone, methanol, isopropanol, toluene,
xylene, dimethyl formamide, and mixtures thereof.
The solvents can be employed in the prepara-
tion of the aromatic halogenated phenoxy resins, in the
preparation of the advanced epoxy resins and in the
compositions o~ the present invention. They are
present in any desirable quantity depending upon the
particular application which is known by those skilled
in the art.
Suitable curing agents which can be employed
herein include, for example, biguanides, imidazoles,
guanidines, aliphatic amines, aromatic amines, multi-
functional phenols, thiols, sul~onamides, and
oombinations thereof. Particularly suitable curing
agents include, for example, dicyandiamide, 2-methyl
imidazole,.tetramethylguanidine, oyanamide, 2-ethyl-4-
-methyl imidazole, ethylenediamine, methylene
dianiline, diaminodiphenylsul~one, meta-phenylene
diamine, phenolic novolac resins from phenol/-
formaldehyde oondenqation products, l,2-benzenedithiol,
sulfanilamide, and mixtures thereof.
Suitable substrates which can be employed
herein include, for example, glass, graphite, aromatic
polyamides, carbon quartz, ceramic, synthetic and
natural ~ibers, and combinations thereof in woven matt
or fibrous form.
The compositions of the present invention may
also contain, i~ desired, pigments, dyes, mold release
agents, flow control agents, fillers, fire retardant
34 , 6 ? 8 -F _9_
'' ' '"', ', ' '
~31~ 9~
--lo--
agents, rubber modifiers, surfactants, accelerators,
reactive diluents, combinations thereof and the like.
The compositions of the present invention are
suitable for such applications as structural or elec-
trical laminates or composites, coatings, adhesives,
castings, moldings, electronic encapsulations and in
potting compositions and the like.
The following examples are exemplary of the
invention but are not to be construed as to limiting
the scope thereof in any manner.
EPOXY Resin A was a diglycidyl ether of
bisphenol A having an epoxide equivalent weight of
181.3.
Advanced Epoxy Resin A was the reaction product
of a diglycidyl ether of bisphenol A having an epoxy
equivalent weight of 188 and tetraorthobromo-bisphenol
A having a phenolic hydroxyl equivalent weight of 272
and a bromine content of 58.7 percent by weight. The
resultant advanced epoxy resin had an epoxy equivalent
weight of 4~3 and a bromine content of 21 percent by
weight.
Halo~enated Phenol A was tetraorthobromo-
bisphenol A having a bromine content of about 58.7
percent by weight and a phenolic hydroxyl equivalent
weight of 272.
Catalyst A was ethyltriphenylphosphonium
acetate-acetic acid complex as a 70% by weight
solution in methanol.
34,618-F -10-
~3Q~3~
Catalyst B was tetrabutylphosphonium
acetate-acetic acid complex as a 70% by weight
olution in methanol.
EXAMPLE 1
A. Preparation of Brominated Phenoxy Resin
Into a 2-liter Parr reactor was charged 235.8 g
(1.3006 epoxy equiv.) of Epoxy Resin A and 349.5 g
(1.2849 phenolic hydroxyl equiv.) of Halogenated Phenol
A followed by the addition of 715 g of methyl ethyl
ketone, 1.358 g (0.0023 equiv.) of Catalyst A and 1.010
g (0.0019 equiv.) of Catalyst B. The reactor was
sealed and heated while stirring to 145C. The pressure
in the Parr reactor reached 68 psig (469 kPa). The
temperature was controlled at 145C for 3 hours at which
time the solution was cooled to room temperature. The
resultant brominated phenoxy resin had an epoxide
oontent of 0.12 percent and a solids content of 35% by
weight.
B. Preparatlan oP Blend of Halo~enated _Phenoxy Resin
and Advanced Epox~ Resin
6.718 g (1.8748 x 10~4 equiv.) of the brom-
inated phenoxy resin prepared in A above was placed in
an aluminum dish and heated in a vacuum oven at 1 75C at
30 5 mm Hg for 2 hours. The resultant solid brominated
phenoxy resin, 0.611 (2.273 x 10-4 equiv.) was blended
with 6.176 g (0.0128 equiv.) of Advanced Epoxy Resin A
by dissolving both in methylene dichloride and then
placing on a 175C hot plate to drive off the methylene
35 dichloride. The resultant blend had a melt viscosity
of 1300 cp (1.3 Pa-s) at 150C. The Advanced Epoxy
34,618-F -11-
. ~3(~:139~:i
Resin A had a melt viscosity of 500 cp (0.5 Pa-s) at
150C.
C. Varnish_Preparation
( l ) 2992 g (6.1927 equiv.) of Advance Epoxy
Resin A dissolved in 748 g of acetone.
(2) 450 g (0.0126 equiv.) of the brominated
phenoxy solution prepared in Example 1-A.
i1 o
(3) 89.8 g of dicyandiamide dissolved in 808 g
of a 50/50 by weight blend of propylene
glycol methyl ether/dimethylformamide.
(4) 2.99 g o~ 2-methylimidazole dissolved in
56.81 g of dimethylformamide.
The above four components were blended together
along with ar additional 1143 g of acetone. This
20 formulation had a Zahn cup visoosity of 22 seconds and
a gel time at 171C oY 270 seconds.
~. Prepre~ and Laminate PreParation
Burlington style 7628 glass cloth with an I617
finish wa~ impregnated with the varnish formulation of
Example l-C in a forced air vertical treater having a
total length of 26 feet (7.9 meters) with the first
19.5 feet (5.9 meters) heated to 350F ( 176.67C) at a
rate of 9 feet per minute (45.72 mm/sec.). The solid
resin contained in the impregnated glass cloth had a
102 second gel time at 171C. The resultant impregnated
glass cloth had a resin content of 42.2% by weight.
Unclad laminates were made from the prepreg by
pressing eight 12" x 12" (3048 mm x 3048 mm) plies at
34,618-F - 12-
;
-13-
500 psig (3447.4 kPa). The temperature in the press
was initially 200F (93.3C) and was increased to 290F
(143.3C) at 7F/min. (0.0648C/sec.). Then the temper-
ature was raised to 350F (176.67C) at 20F/min.
(0.185C/sec.) and held at 350F (176.67C) for 60
minutes. There was no post cure. The physical
properties of the laminate are recorded in Table I.
COMPARATIVE EXPERIMENT A
A. Varnish Preparation
(1) 3200 g (6.6233 equiv.) of Advanced Epoxy
Resin A dissolved in 800 g of acetone.
(2) 168.3 g of PKHH (a phenoxy resin based ~ ~
upon bisphenol A and commercially
available from Union Carbide Corp.)
dissolved in 561 g of methyl ethyl ketone.
(3) 96 g of dicyandiamide dissolved in 864 g
of a 50/50 blend of
dimethylformamide/propylene glycol methyl
ether.
(4) 3.2 g of 2-methylimidazole dissolved in
60.8 g of dimethylformamide.
The above components were blended together
along with an additional 1293 g of acetone. This
3 formulation had a Zahn cup viscosity of 21 seconds and
a gel time at 171C of 247 seconds.
B- Z~ Og~ e, Preparation
The prepreg and laminate were prepared as in
Example 1-D. The prepreg gel time was 85 seconds at
34,618-F -13-
~ 3~3
-14-
171C and the resin content on the glass was 42 percent
by weight. The physical properties o~ the laminate are
given in Table I.
COMPARATIVE EXPERIMENT B
A. Varnish Preparation
(1) 3200 g (6.6233 equiv.) of Advanced Epoxy
Resin A dissolved in 800 g of acetone.
(2) 96 g of dicyandiamide dissolved in 864 g
of a 50/50 blend of
dimethylformamideipropylene glycol methyl
ether.
(3) 3.2 g of 2-methylimidazole dissolved in
60.8 g of dimethylformamide.
The above components were blended together
along with an additional 1014 g of acetone. This
formulation had a Zahn cup viscosity of 19 seconds and
a gel time at 171C of 210 sebond~.
B. Prepre~ and Laminate Preparation
-
The prepreg and laminate were prepared as in
Example 1-D. The prepreg gel time was 90 seconds at
171C and the resin content on the glass was 41.4
percent by weight. The physical properties of the
laminate are given in Table I.
34,618-F -11~-
--15--
TABLE I
PHYSICAL PROPERTIES OF LAMINATES
Comp. Comp.
Phvsical Property Example 1Expt. A Ex~t. B
Laminate thickness, in. 48 48 48
, mm 1219.2 1219.2 1219.2
Tg (DSC)1,C 126 123 125
Tg (DMA)2, C
Initial 130 130 125
After 60 min. exposure
tJ 15 psig (103 kPa),
steam~ C 120 112 ~95
Blister Resistance
sides passedJtotal side 5.5~6 0/6 1/6
lDSC .is Differ~ntial Scanning Calorimetry.
2DMA is Dynamic Mechanical Analysis.
34,618-F -15-
, " , , , ' ;. . . ~ :
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