Note: Descriptions are shown in the official language in which they were submitted.
~ WO 95/10556 PCT/US94/11349
21~17~5
PROCESS FOR PRODUCII\JG A HlGrl MOLECULAR WEIGHT EP~XY RESIN
The present inventlon relates to a process for producing a high molec~lar welgntepoxy resin usefui for adhesives, Insulating mater als, paints and other coatings moldmgs and
5 the like, and more particularly relates to a process for producing a high molecular welgtlt epo~y
resi n i n shorter ti me.
A high molecular weight epoxy resin Is produced by reactmg a bifunctional epoxy
resin having relatively low molecularweight with a divalent phenol compound. This process ,s
generally called an nadvancement" process Regarding the advancement process, for example,
10 Japanese patent publ ication Kokoku 28-4494 d iscloses a process usi ng no sol vent for
polymerization. However, the advanced res~ n made by that process has an average molecular
weight of only about 11,000.
Other advancement processes, which use a solvent for polymerizatjon, are
described in Japanese Kokai 04-12124, 54-52200,60-118757, 60-144323 and 6n-114324. In
these publications, the preferred solvents include methylethyl ketone. methylisobutyl ketone,
cyclohexane, ethyleneglycol monoethylether, ethyleneglycol monomethylethe- and 1~1, N-
dimethyl acetamide.
However, when the high molecuiarweight epoxy resin is produced by uslng a low
boiiing point solvent such as methylethyl ketone, the reaction time becomes qulte ong and a
20 great amount of a catalyst is required, because a reaction temperature cannot be ra;sed Wtlen
a high boiling point solvent such as ethyleneglycol ethylether, ethyleneglycol buty'ethel~ or N,
N-dimethyl acetamide is used, the polymerization can be carried out at a high temperature so
that polymerizatlon time can be shortened somewhat. However, in terms of productlvity, ;l
would be desirable to complete the higher molecular weight polymerizatlon In an even shorter
25 ti me.
The purpose of the present invention is to provide a process to produ~e a higher
molecularweightepoxyresininshortertimebyusingasolventhavinghighernon-toxlcity.
As the result of research and development to solve the above-ment~oned
problems, the inventor discovered that glycol ethers which contain a prirnary hydro)~yl group
30 withrespecttoethergroupsorotherhydroxylgroupsmayreactwithanepo~t,degroupinan
epoxy resin. That reaction terminates the epoxy resin chain and prevents high mo,ecular
weight polymerization.
Q Accordingly, the present Invention provides a process for producmg a high
molecular weight epoxy resin by reacting:
J 35 (1) an epoxy resin which contains on average more than 1 and less than 3
epoxlde groups per molecule with
(2) a divalent phenolic compound which contains on average more than 1 and
ess than 3 phenollc hydroxyl groups per molecule
WO 95tlO556 2 15 1 7 ~ ~ PCT/US9~/11349 ~
characterized in that the reaction takes place in the presence of a giycolether solvent having no
primary hydroxyl groups.
The present invention is particularly described below.
The epoxy resin (hereinaft'er bifunctional epoxy resin) to be used m the present5 invention includes any compound substantially having an average of more than 1 and less than
3 epoxide groups per molecule. The average number of epoxide groups per molecule is
preferably more than 1.8 and less than 3, more preferably less than 2 1, and most preferably
about 2. The bifunctional epoxy resins include, for example, bisphenol A type epoxy resins,
bisphenol F type epoxy resins, bisphenol AD type epoxy resins, bisphenol S type epoxy resins,
alicyclic epoxy resins, aliphatic linear type epoxy resms, diglycidyl ethers of divaler~t phenols,
diglycidyl ethers of divalent alcohols, halides thereof, hydrogenated thereof and the like. Sald
epoxy resins may be used individually, or as any combination thereof. Among said epoxy resins,
the preferable epoxy resi ns i ncl ude bisphenol A type epoxy resi ns and bisphenol F type epoxy
resins. Additionally, the reaction mixture may further contain an additional epoxy component
other than the bifunctional epoxy resin, such as a minor arnount of epoxy novolac resin, as long
as a resultant product has desired properties.
An epoxy resin as a raw material of the present invention is, without intending to
be limited, usually a relatively low molecular weight epoxy resin. The bifunctional epoxy resin
preferably has an epoxy equivalent weight of 170-400 and more preferably 175-250. It
20 preferably has a number average molecular weight of 340-1000 and more preferably 350-500.
In the present invention, for example, D.E.R. '~ 331 L, D.E.R.~ 383J, D.E.R."' 661 (Trademarks of
The Dow Chemical Company) may be used as commercialized epoxy resins.
The divalent phenols in the present invention are used as a chain extender for the
polymerization of the epoxy resin, and may be any of phenol compounds having on average
25 more than 1 and less than 3 phenolic hydroxyl groups, preferably havlng on average 1.8 to 2.1
phenolic hydroxyl groups, most preferably substantially about two phenolic hydroxyl groups.
The divalent phenols include, for example, monocyclic divalent phenols such as hydroquinone,
resorcinol and catechol, polycyclic divalent phenols such as bisphenol A, bisphenoi F, bisphenol
AD, bisphenol S, halogenated versions thereof, alkyl substituted versions thereof and~he like.
30 The above-mentioned compounds are used individually, or as any combination thereof
Among the above-mentioned divalent phenols, the preferable phenols used in the present
invention are bisphenol A, and bisphenol F. Additionally, the reaction mlxture may further
contai n a phenol component other than the divalent phenols, such as a novolac res; n or a
triphenol resln, as long as a resultant product has desired properties.
The equlvalent ratio of epoxide group: phenolic hydroxyl group is usually 0.7 to1.4: 1 and preferably O 9 to 1.1: 1 If the equivalent ratio is less than 0.7, or more than 1.4, the
imbalance in stoichiornetry may redl~ce the molecular weight achieved during advancement.
~C)WO 95/10556 2 1 51 7 ~ 5 PCT/US94/11349
In the present invention, the solvent contains glycolethers having no primary
hydroxyl groups, i.e. hydroxyl groups bonded to a primary carbon atom. The glycolethers
include propyleneglycol ethers having a hydroxyl in ~3-position. The propyleneglycol ethers in
the present invention are able to dissolve raw materials such as the epoxy resins and the
5 phenols, and include, for example, propyleneglycol methylether, propyleneglycolmethylether
acetate, propyleneglycol propylether, propyleneglycol monobutylether and the like The
preferable propyleneglycol ether is propyleneglycol monobutylether
The glycol ether solvent preferably has a boiling point higher than 140C and
morepreferablyhigherthanl65C. Themaximumboilingpointisnotcritical,butitis
10 preferably no higher than 300C For the purpose of dissolving the advanced resin, another
solvent, for example, such as ketone solvents, amide solvents, ether solvents or aromatic
solvents may be added after the advancement is completed.
The solvent content is preferably 10% to 50% of the reaction mixture, and, more
preferably 20% to 40% of the reaction mixture. If the solvent content is less than 10%, the
viscosity of the resin may quickly build to high for effective agitation. On the other hand, lf the
solvent content is more than 50%, the reaction rate may be too slow.
The polymerization of the present invention is preferably carried out using a
catalyst. The catalysts include, for example, imidazoles such as 2-methyl imidazole, tertiary
amines such as triethyl amine, tripropyl amine and tributyl amine, phosphonium salts such as
20 ethyltriphenylphosphonium chloride, ethyltriphenylphosphonium bromide and
ethyltriphenylphosphonium acetate, ammonium salts such as benzyltrimethylammonium
chloride and benzyltrimethylammonium hydroxide. Suitable catalysts for the present
invention are highly active catalysts capable to be used in higher temperature, preferably
phosphorous catalysts, especially phosphonium salts such as ethyltriphenylphosphonium
25 acetate. The catalyst concentration is preferably 0.001 to 10 percent by weight, and more
preferably 0.01 to 5 percent by weight, based on the reactant solids. If the advanced epoxy
resin is intended for food can coating applications, the concentration of the catalyst is most
preferably less than 0.25 percents by weight.
In the present invention, the polymerization reaction is carried out at a rather30 high temperature which is lower than both of the boiling point of the polymerization solvent
and the decomposition temperature of the polyrnerization catalyst. The temperatu~e of the
advancement reaction is preferably 100 to 250C and more preferably at 120 to 200C. The
reaction time is preferably 1 to 12 hours and more preferably 3 to 7 hours Tne polymerization
reaction may be carried out by a continuous process or a batch process, under atmospheric
35 pressure, higher pressure or reduced pressure.
The advanced epoxy resin made by the process of the present inventior
preferably has a weight average molecular weight of 20,000 to 200,000, and more preferably
50,000 to 150,000 The molecular we~ght aistribu~lon ~Mv~,~Mn) of the advanced resi n ~s
-3-
W0 95/10556 2 ~ 5 PCT/US94/11349 0
preferably 2 to 15 and more preferably 4 to 11. Furthermore, the process of the present
invention can be used, under preferred conditions and using preferred reagents, to produce an
epoxy resin having more than 50,000 (and preferably more than 70,000) weight average
moiecular weight in 3 to 7 hours.
The high molecular weight epoxy resin produced by the process of the present
invention may be used as adhesives, insulating materials, moldings solution and powder
coatings and the like, and preferably used as paints, more preferably used as paints for metal
can coating.
EXAMPLES
The present invention is particularly illustrated by the following examples. In the
examples, "parts" means''partsbyweightU.
Examples 1-2 and Comparative Examples A-D:
A series of reaction mixtures were made which contained the following components:
(1) aliquidepoxyresinwithanepoxyequivalentweightofabout180,inthe
quantities shown in Table 1;
(2) bisphenol A in the quantities shown in Table 1;
(3) aboutO.18%(basedonsolidresin)ofethyltriphenylphosphoniumphosphateas
catalyst; and
20 (4) the solvent and quantity of solvent shown in Table 1
Each mixture was reacted for 4 or 7 hours at about 170C. A sample of the resulting advanced
resin was recovered, and its weight average molecular weight was measured by gel permeation
chromatography using polystyrene standards. The results are shown in Table 1. The
Comparative Examples are not examples of the present invention
~ W09S/lOSS6 PCT/US94/11349
215~7~5
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. o o
~ o ~ o o o
o ~ Lo~ u~ o o
L
.~ I~ o ~ o o o
0 G ~ m o r~
L
~ O -- Lf)
~ ~ ~ o -- Ln
L
a~
~ ' E ~ ~ o 0 o o
": ~ Ln ~D.
_ ~ o ~ o o
E ~ D o -- ,~ o
~ LX
~ ~o o -- I` ~ I
LX
E L E o ,~ ou
WO 9S/lOS56 2~ 5 PCT/US9~/11349
Abbreviation in Table 1 shows the following compound respectiveiy
LER: Bisphenol A type epoxy resin
BIS-A: Bisphenol A
PnB: Propyleneglycol monobutylether
ETPPA: Ethyltriphenylphosphonium acetate
ETPPP: Ethyltriphenylphosphonium phosphate
EVALUATION RESULT
Comparing Example 1 with Comparative Example A-C, the high molecular weight
10 polymerizationto 129~oooofawei9htavera9emolecularwei9htwasavailableby4-hour
polymerization according to the process of the present invention. However, in the
polymerization carried out at substantially the same conditions except the solvent used in
Comparative Example A-C, the high molecular weight polymerization only to 45,000-56,000 of
a wei ght average mol ecu lar weig ht was avai labl e. Therefore, it was fou nd that the present
invention remarkably enables to a high molecular weight polymerization at the same
condition as known process.
Comparing the result of Example 2 with Comparative Example D, Example 2
achieved an about 3-time high molecular weight polymerization in weight average molecular
weight, comparing to Comparative Example D, at substantially the same conditions even
20 though the reaction activity was decreased because of the use of ethyltriphenylphosphonium
phosphate as polymenzation catalyst. Therefore, it was found that the present inventlon
remarkably enables to a high molecular weight polymerization in the same conditions as
known process.
As described above, according to the process of the present invention, a higher
25 molecular weight epoxy resln can be produced in shorter time comparing to a prior process
using the currently used polymerization solvent.
