Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~23~ .
The invention rela-tes to -the preparation of substituted
1,4-diaminobutanes and the use of these compounds as curing
agents for epoxide resins.
1,4-Diaminobu-tanes o~ this type are men-tioned in a
publica-tion by H. Schafer in Angew. Chemie 82 (1970) 134 as
analysis products obtained in a small amount. In the case
of the preparation described in this publication, for example,
a mixture of a-methylstyrene, glacial acetic acid and sodium
azide is subjected to electrolysis. This results in the
formation of 1,4-diazido-2,3-dimethyl-2,3-diphenylbutane, with
the evolution of a small amoun-t of nitrogen. After the
product has been separated off, it can be catalytically hydro-
genated in solution to give 1,4-diamino-2,3-dimethyl-2,3-di-
phenylbutane.
This process of the state of -the art, which is intended
only for analysis, has, however, the serious disadvantage that
azides, which, as is known, are explosive products, are obtained
as intermediates. Moreover, the yield from thls process is
relatively low.
The subject o~ the present invention is a process fo~
the preparation of 1,4-diaminobutanes of the general formula I
: .
~1 (I)
2 2 ~2 R3 2 2
in which Rl is H or -CH3 and R2 and R3 independently of one
another are each a radical of the ~ormula
~,
_
.
~ ~ A
in which A is alkyl having 1 to 3 C atoms, -OCH3, -N(CH3)2,
-C:L or -Br 9 and R is also alkyl having 1 -to 3 C atoms, wherein
first a) a succ1nic acid dinitrile of -the formula II
R
NC - C - CH ~ CN (II)
~2 l3
is ca-talytically hydrogenated at temperatures of 20 -to 150C
in the presence of acetic anhydride and, if desired, of addi- :
.:
tional inert organic solvents, then b) the N,N'-diacetyl-1,4- :
diaminobu-tane obtained by the hydrogenation is subjected, after
isolation if desired, to acid or alkaline hydrolysis in~an
aqueous medium and, finally, c) the 1,4-diaminobutane of the
formuIa I is isolated either .in the ~orm of a salt or, after
neutralisation with alkali, in the form of the ~ree base.
A succinic acid dinitrile of the ~ormula II in which
Rl is H or -CH3, R2 is one of the radicals CH
~ C1 ~ H3
and alkyl having up to 3 C atoms and R3 is one of -the radicals
~ ~ Cl and ~ 0 CH3
it being possible for R2 and R3 to be iden-tical or difXerent,
is preferably used in the process according to -the invention.
In a par-tlcular embodiment of the process according to
:'
,, ~
-the invention, a succinic acicl dinitrile of the formula II is
employed in which Rl is H and R2 and R3 are each a radical of
the formula
~ or ~ ~
in which A is alkyl having 1 to 3 C a-toms, preferably -CH3,
or -OCH3, -N(CH~)2, -Cl or -Br, preferably -Cl.
The substituted N,N'-diacetyl-1,4-diaminobutane
obtained as an intermediate in the process according to the
invention is of the formula IV
CH3.CO.HN - CH~ - C CH _ CH2 - NH.CO.CH3 (IV)
. R2 R3~ .
. ; ;~ . :
in which Rl, R2 and R3 are as~defined in formula II. The
N,N'-diacetyl derivatives of the :Eormula IV haYe not yet been ~ -
described in the literature and are thus valuable starting
compounds for the preparation of -the 1,4-diaminobutanes of -the ~
formula I. - -
A succinic acid dinitrile of the formula II which is
particularly preferentially employed is a succinic acid di-
nitrile of the formula III
NC CH CH - CN
~ ~ (III)
This product can be prepared, for example, by reacting banz-
aldehyde, benzyl cyanide and sodium cyanide. Other di-
nitriles of the formula II which are -to be used as starting
. :
3~i~
materials for the process according to the invention can also
be prepared correspondingly. More precise information on
the reac-tion is -to be ~ound in the publication by R.B. Davis
in J. Amer. Chem. Soc. 80 (1958) 1,752. All of the di-
nitriles lis-ted in Table I in this publica-tion can be employed
as s-tarting ma-terials ~or the process according to the inven-
tion. Other dini-triles not mentioned in Table I can, of
course, also be employed if they correspond to the formula II.
The temperature suitable for the hydrogenation accord-
ing to stage a) is in each case dependent on -the hydrogena-tion
catalyst used. If Raney nickel or Raney cobalt is used,
the reaction condi-tions are op-timum, in respect of the yield,
when tempera-tures of about 90 to 1~0C are used. When
known noble metal catalysts, such as platinum, palladium,
rhodium or ruthenium, are employed, the reaction can be carried
out at lower temperatures, such as, say, at room temperature.
The hydrogenation can be carried out by the methods
customary in the laboratory and in industry, either under
normal pressure, for example in a duck-shaped shaking vessel,
or under pressure in an autoclave.
Additional inert organic solvents which can be used for
the hydrogenation are, for example, hydrocarbons or ethers,
such as hexane and dioxane, or aroma-tic compounds, such as
toluene or benzene.
The catalytic ~eduction is as a rule carried out by
mixing a solution of the particular succinic acid dinitrile of
the formula II in acetic anhydride and, if desired, a solvent
~..,;
5 --
with the ca-talyst and passing hydrogen gas into the reaction
mix-ture. The hydrogenation is continued ~mtil no further
hydrogen is absorbed. The catalyst is then separated off.
In -the second stage b), the resul-ting subs-tituted
N,N' diacetyl-1,4-diaminobutane is generally firs-t isolated
and then subjected to acid or alkaline hydrolysis. In
principle~ however, -the hydrolysis can also be carried out
withou-t separating OI'f the diace-tyl compound, i.e. direct in
the solution, which has been freed from the catalyst, and is ob-
tained from stagea)~ The intermediate is isolated by known pro-
cesses.
The acyla-ting hydrogenation in -the presence of acetic
anhydride employed in stage a) of the process according to the
invention is known per se but in the present case ultimately ~ -
results in solid, substituted 1,4-diaminobutanes which, sur- --
prisingly, are outs-tandingly sultable as curing agents ~or
epoxide resins in respect of po-t life, colour s-tability and
stability to aggressive media, especially organic acids and
alcohols, and some of which are even superior to some con-
~entional curing agents. This is the case, in particular,
for adduct curing agents obtained from the substituted 1,4-
diaminobu-tanes,which can be prepared by the process according
to the invention,and liquid polyepoxide compounds.
The 1,4-diaminobutanes of the ~ormula I which can be
prepared according to the invention are also particularly
suitable for the production of pre-reaction products with
epoxide resins (B-stages). For the preparation o~ such
- 6 ~
,
3~3L
R-stages, as is known, the corresponding epoxide resin is
mixed with the curing agent and the mixture is stored either
at room temperature for about 1 to 14 days or at slightly
elevated temperature (not higher than 60C) for one or se~eral
hours. The B-stages which form during'this storage are : .
u~ed, a~ nown, lnter alia ~ compre3~isn mouldlng compo-
sitions, pre-pregs for laminates, sintering powders a~d
adhesives. Those based on the 1,4-diaminobutanes of the
formula I which can be prepared according to the invention are
suprisingly superior to the conventional B~stages which, as is
known, contain predominantly aro~atic amines as the ouring
agents. This superiority is particularly surprising
because the basic character of the 1,4-diaminobutanes o~ the
formula I is rather that of aliphatic amines. However,
as is known, aliphatic amines are unsuitable in practice for
the preparation of B-stages~
The invention further also re:Lates to cura~le mlxtures
containing a 1,4-diaminobutane o~ the formula I and a poly-
epoxide compound (designated X here) having, on a~erage, more
than one epoxide group in the molecule, there being9 in the
mixtures, 0.5 to 1.5 equivalents o~ active hydrogen atoms,
bonded to nitrogen,.in the particular 1,4-diaminobutane per
1 equivalent of epoxide groups in the epoxide compound (X).
A preferred form of the curable mixtures accordi~g to
the invention comprises those which contain the 1,4-diamino-
butane of the formula I in the form of an adduct curing agent
(E) having an amine number of 4.0 to 4.7 ob-tained from the
~ diaminobutane of the formula I and a liquid epoxide com-
pound (designa-ted Z here) having, on average, more -than one
epoxide group in the molecule and, if desired, phenylglycide.
In such mixtures there are 0.8 -to 1.2 e~uivalents of active
hydrogen atoms bonded to the nitrogen atoms ol the adduct
curing agen-t (E) per l equivalent of epoxide groups in the
epoxide compound (X). Bisphenol A epoxide resins or bis-
phenol F epoxide resins are preferably employed as liquid
epoxide compounds (Z) for the preparation of the adduct curing
agen-ts (E). The preparation of the adduct curing agents
(~) is preferably effected by warrning a mixture of a 1,4-
diaminobutane of the forrnula I, an epoxide compound (Z) and,
if desired, phenylglycide (molar ra-tio: l.0 : 0.13 : 0.2) to
temperatures of 12GC to 200C.
The adduct curing agent (E) can additionally also con-
tain 5 to 10% by weight, relative -to the pure adduct curing
agent, of salicylic acid as a reaction accelerator.
The invention further also relates to the B-stages
which are stable on storage and have already been described
and which are to be regarded as a preferred form of -the curable
mixtures according -to the invention.
Polyepoxide compounds (X) which can be used for the
curable mixtures according to the invention are~ in particular,
those having on average more than one glycidyl group, ~-methyl-
' ' ', .
315~ :
glycidyl group or 2,3-epoxycyclopentyl group bonded to a -:
hetero-atom (for example sulphur and preferably oxygen or
nitrogen~; preferred compounds are bis-(2,3~epoxycyclo-
pen-tyl) e-ther; di- or poly-glycidyl ethers of polyhydric
aliphatic alcohols, such as 1,4-butanediol, or polyalkylene
glycols~ such as polypropylene glycols; di- or poly-glycidyl -
ethers of cycloaliphatic polyols, such as 2,2-bis-(4-hydroxy-
cyclohexy].)-propane; di- or poly-glycidyl e-thers of poly-
hydric phenols, such as resorcinol, bis-(p-hydroxyphenyl)-
methane, 2,2-bis-(p-hydroxyphenyl)-propane (= di~methane),
2,2~bis-(4~-hydroxy-3~,5 t -dibromophenyl)-propane, 1,1,2,2-
tetrakis-(p-hydro~yphenyl)-ethane or of condensation products
of phenols with formaldehyde obtained under acid conditions,
such as phenol novolacs and cresol novolacs; di- or poly- -~
(~-methylglycidyl) ethers of the abovementioned polyhydric
alcohols or polyhydric phenols; polyglycidyl esters o~ poly-
basic carboxylic acids, such as phthalie acid, tereph-thalic
acid~ ~4-tetrahydrophthalic acid and he~ahydrophthalic acid;
N-glycidyl derivatives o~ amines, amides and heteroeyeIie
nitrogen bases, such as N,N-diglycidyl-aniline, N,N-diglycidyl-
toluidine and N,N,N',N~-tetraglyeidyl-bis-(p-aminophenyl)-
methane; triglycidyl isocyanùrate; N,N'-diglycidylethylene-
urea; N,N'-diglycidyl-5,5~dimethyl-hydantoin and N,N'-di-
glycidyl-5-isopropyl-hydantoin; and N,N'-diglycidyl-5,5-
dimethyl-6-isopropyl-5,6-dihydro-uracil.
I~ desired, active diluents, for example styrene oxide,
; butyl glyeidyl ether, isooctyl glycidyl ether, phenyl glyeidyl
: - ~ ' , ',
';,
~2~
ether~ cresyl glycidyl ether or glycidyl esters of synthetic,
highly branched, mainly -tertiary aliphatic monocarboxylic acids
("CARDUR~ E"), can be added to the polyepoxides in order to
lower the viscosity.
The curing of the curable mixtures according to the
invention -to give mouldings and the like is carried out in the
temperature range of 20 to 160C when the free 1,4-diamino-
butanes of the formula I are used. However, if the mix--
-tures contain the described adduct curing agents of -the 1,4- -
diaminobutanes, curing is preferably carried out at tempera-
tures of 5 to 250C.
In order to shorten the gelling times or curing -times,
known accelerators for the amine curing reaction, for example
monophenols or polyphenols, such as phenol or dlomethane,
salicylic acid, tertiary amines or salts of thiocyanic acid,
such as NH4SCN, can be added.
Furthermore, conventional modifiers, such as ex-tenders,
fillers and reinforcing agents, pigments 9 dyes, organic sol-
vents, plasticisers, flow control agents, agents for conferring
thixotropy, ~lameproofing agents and mould release agents, can
be added to the curable mix-tures, according to the invention,
of polyepoxide compounds (X) and 1,4-diaminobu-tanes of the
formula (I) or corresponding adduct curing agents in any stage
before curing.
The following may be mentioned as examples of extenders,
reinforcing agents, fillers and pigments which can be employed
in the curable mixtures according to the invention: coal tar,
_j
-- 10 --
:.. , ~ . .
., .
351 :`
bi-tumen, liquid coumarone-indene resins, -textile fibres, glass
fibres, asbes-tos fibres, boron ~ibres, carbon fibres, cellu-
lose, polyethylene powders and polypropylene powders; quartz
powder; mineral silicates, such as mica, asbestos powder or
slate powder; kaolin, aluminium oxide trihydrate, chalk powder,
gypsum, antimony trioxide, bentones, silica aerogel ~"AEROSIL"),
lithopones 9 baryte, -titanium dioxide, carbon black, graphite,
oxide colours, such as iron oxide, or metal powders, such as
aluminium powder or iron powder.
Suitable organic solvents for modifying the curable
mixtures are, for example, toluene, xylene, n-propanol, butyl
acetate, acetone, methyl ethyl ketone, diacetone alcohol,
ethylene glycol monomethyl ether, ethylene glycol monoethyl
ether and ethylene glycol monobutyl ether.
Examples o~ plasticisers which can be employed for ~-
modi~ying -the curable mixtures are dibutyl phthalate, dioctyl ;-
phthalate and dinonyl phthalate, tricresyl phosphate, trixyl-
enyl phosphate, diphenoxyethylformal and polypropylene glycols.
These plasticisers can also already be constituents o~ the
curing agent, especially of the adduct curing agent. In
such cases, the plasticisers are present in a concentration of
25 to 50/O by weight, relative`to the pure curing agent.
Examples of ~low control agents whioh can be added
when the curable mixtures are employed particu]arly in surface
protection are silicones, liquid acrylic resins, cellulose
acetobutyrate, polyvinylbutyral, waxes, stearates and the like
(some of which are also used as mould release agen-ts).
3~
Particularly for use in the lacquer field, the poly-
epoxide compounds can furthermore be partially esterified in
a known manner with carboxylic acids, such as, in particular~
hlgher unsa~urated fat-ty acids. It is also possible -to
add o-ther curable synthetic resins, for example phenoplasts
or aminoplasts, to such lacquer resin formulations.
The curable mixtures according to the invention can be
produced in a conventional manner with the aid of known mixing
equipment (stirrers, kneaders, rolls, or, in the case of
solid powders, mills or dry mixers).
The curable epoxide resin mixtures according to the
invention are employed in particular in the flelds of surface
protection, -the electrical industry, laminating processes and
adhesives technology and in -the building trade. They can
be used in a formulation suited ln each case to the particular
application, in the unfilled or filled state, if appropriate
in the form of solutions or emulsions, as paints, lacquers
and solvent-free coatings, as sintering powders, compression
moulding compositions~ injection moulding formulations, dipping
resins, casting resins, impregna-ting resins, binders and adhe-
sives and as tool resins, laminating resins, sealing and filling
compositions, floor covering compositions and binders for
mineral aggregates.
Example 1
Precursor: N,N'-Diacetyl-1,4-diamino-2,3 diphenylbutane
34.9 g (0.15 mol) of 2,3-diphenyl-succinic acid
- 12 -
, ~
. '''
3~.
dinitri:Le are hydrogena-te~ at 120-125C and under a pressure
of 120 atmospheres gauge in 200 ml of toluene and 35.3 g
(0.36 mol) o~ acetic anhydride in an autoclave in the pre-
sence of 3.5 g of Raney nickel. me absorption of H2
has ceased after 30 minutes and N,N'-diace-tyl-1,4-diamino-
2,3-phenylbutane crys-tallises ou-t on cooling. The super-
natant solution is decanted off and the residue is boiled
wi-th 300 ml of ethanol~ whereupon the produc-t dissolves.
In order to separate of~ the catalyst, the mixture is fil-
tered ho-t and the filtrate is partially concentrated. The
product then crystallises ou-t and is filtered off a-t room
temperature, washed with ethanol and dried a-t 80C. Yield:
30,5 g; melting point: 221-222C. A further 3.4 g of
substance are obtained by concentrating, so tha-t the total
yield is 33.9 g (69.5% of -theory). For analysis, 1 g is
recrystallised from 10 ml of ethanol. Yield: 0.8 g;
melting point 221-222C.
Analysis C20H24N2o2 (molecular weight = 324.41)
- calculated C 74.04 H 7.46 N 8.64
~- found C 74.11 H 7.58 N 8.68
The NMR spectrum agrees with the structure.
1, 4-Diamino~,3~ph~1butanè
385.7 g (1.19 mols~ of N,N'-diacetyl-2,3-diphenyl-1,4-
diaminobutane in 715 ml of 5N sodium hydroxide solution are
heated to 200C in an autoclave for 16 hours. After cooling,
the mixture is extracted with 1,800 ml of chloroform.
Further extraction with 2 times 200 ml of chloroform and
- 13 -
concentration of the extrac-ts gives 285.4 g of crude product,
which is recrystallised from 2.6 1 of benzene. Yield:
258.5 g of 1,4~diamino-2,3-diphenylbu-tane; melting point:
144-145C. A fur-ther 15.1 g of substance having a melting
point of 144-145C are obtained by concentrating the mother
liquor; -the total yield is thus 273.6 g (95.7% of ~theory).
For analysis, 1.0 g is recrystallised from 10 ml of benzene.
Yield: 0.88 g; melting poin-t: 144~145C; meso ~orm.
Analysis Cl~H20N2 (molecular weight = 240.34)
calculated C 79.95 H 8.39 N 11.66
found C 79.88 I-I 8.31 N 11.69
The NMR spectrum agrees with the structure.
Example 2
Precursor: N,N' Diacetyl 1,4-diamino-2-(p-chlorophenyl)-3-
(p-methoxyphenyl)_butane.
29.6 g (0.10 mol) of Z-(p-chlorophenyl)-3-(p-methoxy-
phenyl)-succinic acid dinitrile are hydrogenated for 4 hours
at 110C and under a pressure of 100 atmospheres gauge in
200 ml of toluene and 25 g (0.24 mol) of acetic anhydride in
an autoclave in the presence of 3 g of Raney nickel. The
-totàr-reaotion mixture is then concentrated in a rotary evapo-
rator, the residue is boiled ùp with 700 ml of ethanol and the
Raney nickel is filtered off. After concentrating the fil-
trate to 200 ml, the product crys-tallises out. After
filtering off, washing and drying, 19.0 g (48.8% of theory)
of a substance having a melting point of 235-238C are obtained.
The filtrate is completely evaporated in a rotary e~aporator;
- 14 -
~Z3~
recrystallisa-tion of the residue ~rom 100 ml of ethanol gives
a fur-ther 2.3 g of produc-t having a melting poin-t of 232-236C.
To-tal yield: Z1.3 g (54.7% of theory).
1?4-Diamino 2~ chl~x~hen~])-3-~p-methoxy~henyl)-butane
, .
21.14 g (0.054 mol) of N,N'-diacetyl-1,4-diamino-2-
(p-chloroFhenyl)-3-(p-methoxyphenyl)-bu-tane in 80 ml of 15%
s-treng-th aqueous sodium hydroxide solution are heated to 200C
in an autoclave for 12 hours. Af-ter cooling, the mixture
is extrac-ted with chloroform and the organic phase is washed
with water and then evaporated in a rotary evaporator.
Yield of crude product: 13.2 g (79.6% of theory) of a
crystalline product. For purification, this product is
recrystallised ~rom 200 ml o~ cyclohexane, then filtered of~,
washed with cvclohexane and dried in vacuo at 60C. Yield:
~,,
11.55 g (69.6% of theory~; melting point: 124-127C.
Analysis C17H21N20Cl (mQlecular weight = 304.82)
calculated C 66.99 H 6~94 N 9.19
found C 67.06 H 6.87 N 9.09
~ ' .
Precursor: N,N'-Diacetyl-1,4 diamino-2-p-tolyl-3-phenyl butane.
24.6 g (0.10 mol) of 2-p-tolyl-3-phenyl-succinic acid
dinitrile are hydrogena-ted at`l20C and under 100 atmospheres
gauge in 250 ml of toluene and 31 g (0.30 mol) of acetic
anhydride in an autoclave in the presence of 2.5 g of Raney
nickel until a constant pressure is reached. The total
mixture is concentra-ted to about 100 ml in a rotary evaporator,
600 ml of ethanol are added, the mixture is heated to the
- 15 ~
2;3S3L
reflux temperature and the ca-talys-t is filtered off hot.
Af-ter concen-trating the flltra-te to about 300 ml, -the product
crystallises out on cooling in a refrigerator. Yield:
18.5 g (54~6% of theory); melting po~nt: 226-7C. A
fur-ther 3.0 g (8.9% of theory) of produc-t having a melting
point of 222-6C are ob-tained by concen-tra-ting the mother
liquor. Recrystallisation of 0.80 g of the ~irst frac-
tion from 12 ml of e-thanol gives 0.49 g of pure product having
a melting point of 226-7C.
~nalysis C21H26N202 (molecular weight = 338.45)
calculated C 74.53 H 7074 N 8.28
found C 74.39 H 7-71 N 8.49.
~ i! 18.6 g of N,N~-diacetyl-1,4-diamino-2-p-tolyl-3-phenyl-
butane in 80 ml of 15% strength aqùeous sodium hydroxide solu-
tion-are heated to 200C in an au-toclave for 16 hours~ On
concentrating the solution, the amine partially crystallises
out. The mixture is extracted 3 times with 50 ml of
chloroform and after evaporating the extracts in a rotary
evaporator 13.8 g of crystalline crude amine are obtained.
Recrystallisation from 110 ml of cyclohexane gives 12.2 g
(87.3% of theory) of diamine having a melting point of 112-14C.
Analysis C17H22N2 (molecular weight = 254.38
calculated C 80.27 H 8.72 N 11.01
found C 80.05 H8.64 N 11.34.
. ~ , .
,
- 16 -
~ .
, ' ' ,~ ' . .
,:,.. , ~ .
3~l
.
Precursor: N,N'-Diacetyl-1,4-diamino~2-(p-dimethylamino-
phenyl)-2-phenyl butane.
13~4 g of 2-(p-dimethylamino-phenyl)-3-phenyl-succinic
acid dinitrile are hydrogena-ted a-t 120C and under 100 atmos-
pheres gauge in 250 ml of toluene and 15 g of acetic anhydride
in an autoclave in the presence of 1.5 g of Raney nickel until
constant pressure is reached. The mixture is concentrated
to 50 ml, 300 ml of e-thanol are added and J a~ter boiling up,
the catalyst is filtered off. All of the solven-ts are
then removed in a rotary evaporator and the reside is recry-
stallised from 60 ml of acetonitrile. 3.1 g of a product
having a melting point of 205-9C are obtained in the first
fraction. The NMR spectrum is in agreement with the ~`
structural formula
~ ~ ~ '
19.1 g of N,N'-diacetyl-1,4-diamino-2-(p-dimethyl
aminophenyl)-3-phenyl-butane in 80 ml of 15~ strength aqueous
sodi~n hydroxide solution are heated to 200C in an autoclave
for 16 hours. The reac-tion solu-tion is then concentrated
in a rotary evaporator and extracted with chloroform. After
. .
removing the chloroform in vac~o, 8.5 g of crys-talline crude
amine are obtained and this is recr-ystallised from 35 ml of
isopropanol. Yield: 3.8 g of product having a melting
point o~ 145-146C. A further 2.0 g of product having a
melting point of 145-146C are obtained by concentrating.
Analysis C18H25N3 ~molecular weight = 283.
- 17 -
;
s~
calculated C 76.28 H 8.90 N 14.8~
found C 76.26 H 8.93 N 14.74.
B) Use Ex~
-
(Casting and adhesive resin)
31.8 g of 1,4-diamino-2,3-diphenylbutane are homogen-
ised, by means of a triple roll mill, together with ~00 g of
a liquid unmodified epoxide resin (X) which is based on bis
phenol A and has an epoxide content o~ 5.3 equivalentjkg and
a viscosi-ty of 10 9 800 cP/25, a viscous white suspension being
obtained.
The following methods are used to determine the various
characteristics:
Differential thermal analysis is used to determine -the
reactivity. About 20 mg of -the resin/curing agent mixture
to be tes-ted are warmed in a small Al crucible in the measuring
chamber of a type TA 2000 differential thermoanalyser from
Messrs. Mettler (Greifensee, Switzerland) at a heating rate
of 4/minute and the temperature difference between this
crucible and an empty crucible warmed at the same time is
recorded continuously. The temperatures for the start of
reaction, for the maximum reaction rate and for the end of
the reaction are read off, as parameters characterising the
reactivity, ~rom the curve thus obtained. The area under
the`curve enables the heat liberated during the reaction to be
determined and gives an indication of the completeness of the
conversion.
- 18 -
..
~,
,
:;` ' ~
b) Determination of_-the lass transition -temperature
'4 g of -the resin/curing agent mix-ture are, in each
case, poured in-to a thin-walled Al crucible of about 5 cm
diame-ter and cornpletely cured in this crucible (4 hours at
80C and 8 hours at 140C). A sample is -taken from the
disc thus obtained in order to determine the glass transition
temperature of -the crosslinked polymer with the aid of differ-
en-tial thermal analysis. The specific heat changes at
the transition point; this change is registered as a turn-
ing point in the curve recorded by the DTA apparatus.
Conclusions regarding the dimensional stabili-ty of the result~
ing polymer when ho-t can be drawn from the glass transition
tempera-ture.
c) Determination of the mechanical and dielec-tric properties
The resin/curing agent mixture prepared as described
above is poured into aluminium moulds, which have been pre-
treated with mould release agents, in order to produce sheets
having dimensions of 135 x 135 x 4 mm and 135 x 1~5 x 2 mm
and the sheets are cured for 4 hours at 80C and 8 hours at
140C.
The 4 mm thick sheets~are used to produce test pieces
having dimensions of 60 x 10 x 4 mm for determining the flexu-
ral strength and deflection according to VSM Standard
Specifica-tion 77,103, the impact strength according to VSM
Standard Specification 77~105 and the increase in weight after
storage in water.
-- 19 --
''
,, . .. , : ~
~235~L
The 2 mm thick sheets are used to determine the
diélectric properties.
d~_Test to deter ne the suitabil ty as an adhesive
A small amoun-t of the resin/curing agent mixture is
applied, in each case, -to the ends of test strips made of
anticorodal B which have dimensions of ]70 x 25 x 1.5 mm and
have previously been roughened by grinding and degreased by
washing with solven-ts. In each case, two of these test
strips are so adjusted with -the aid of a gauge that the ends
coated wi-th resin/curing agent mixture overlap by 12 mrn.
After fixlng with a clamp, the adhesive is cured and after
cooling the clamp is removed and the -tensile shear strength
o~ the glue bond is then tested in a tensile test (DIN 53,183~.
~ ::
A small amount of the resin/curing agent suspension is
distributed on a sheet of glass by means of a glass rod so
that a uniform film is obtained. The coating obtained
after curing is tested to determine its chemical stability by
leaving a drop o~ the par-ticular chemicals on the film ~or 1
hour. The chemicals are then wiped off and the sur~ace
of the film is assessed visually.
The characteristics de*ermined for the various test ?
pieces by the methods mentioned are summarised in Table 1.
EXample I shows -that mixtures of 1,4-diamino-2,3-
diphenylbutane and epoxide resins are very reactive and give
mouldings with good mechanical and electrical proper-ties and
a high glass transition temperature. If the mix-tures are
- 20 -
.
'' ~ .
~Z.~
applied in a thin layer in the form of a solven-t-free coa-ting,
films are obtained which have very good stability towards
solven-ts and aggressive chemicals in aqueous solution.
Mixtures of thls type can also readily be used for glue bonds.
- 21 -
Table 1
(relating to Example I)
100 par-ts of epoxide resin
Sys-tem based on bisphenol A
31.8 parts of 1,4-diamino-2,3-
diphenylbutane
~ ,
T~ 2000 TRRmax 102
TE 177
En-thalpy 20,815 cal/equivalent of
epoxide/amine sys-tern
Curing 4 hours at 80C
Appearance of -the moulding
material whlte, opaque
~ . _
Impact strength (cmkg/cm2) 5-5
Flexural strength (kg/mm2) 9.2
Deflection (mm) 3.2
Glass -transition temperature (C) 151
Absorption o~ H O, 4 days at
room tempera-ture2 ~%) 0.29
Absorption of H20, 1 hour in
boiling water (%) 0.63
Tensile shear streng-th (kg/mm2~ 1.7
_
Chemical stabili-ty towards .
5N H2S4
5N NaOH no attack o~ any type
.H20 . de-tectable
acetone -
Cl-benzene
Loss fac-tor tan ~
>1% above 79
~5% above 104
Dielectric constant at 25C 3.6
Specific volume resistivity
25 (~xcm) 4.7x1016
- 22 -
,
LL~
TRRmaX = Temperature a-t the maximum ra-te of reaction
TS = Temperature a-t -the star-t of the reaction
TE = Tempera-ture a-t the end of the reaction
(Solvent-free coating systems)
Preparation of the_adduct curin~ a ents
Addwct curin~ agent I according -to the invention
50 g of a liquid epoxide resin (Z) based on bisphenol
A and having an epoxide equivalent weight of 168 and a vis-
cosity of about 37400 cP (25C) are mixed together with 180 g
o~ diphenoxyethylformal and 240 g of 1,4-diamino-2,3-diphenyl-
butane in a -three-necked flask and the mixture is heated to
150C. 30 g of phenylglycide are then added dropwise and
the mixture is reacted at 150-170C for 25 minutes. After
cooling to about 120C, 35 g of salicylic acid are melted into
the mixture, with stirring. The finished adduct curing
agen-t is-discharged at about 50C. Charaoteristics: see
Table 20
(as comparison)
Base~ on: 4,4' diamino-diphenylmethane.
Table_2
(Charac-teristics of the curing agents according to Example II)
. . .. . ~ _~ ~
Curing Viscosi-ty Amine H equivalen-t Suitable mixing
agent a-t 25C in number weight ra-tio of epoxide
cP (accord- resin to be cured:
ing to adduct curing
Ho0ppler) agent
. .. ._ ~ ~_... ~ - . .. . . . .~
I ~100,000 4.5 127 100:66
_ _~ _ __ . .
II 6,700 4.5 115 100-60
~ 23 -
,_,, .. , .. . , .,.. ,.. ,,.. , ., ., .... ... ............ , ... ........ ,... , . ... .. ... , -.-
P~
A liquid bisphenol A epoxide resin (X) hav:ing a vis- :
cosi-ty of 11~300 cP at 25C and an epoxide equivalent weigh-t
of 194 is mixed wi-th -the aclduct curing agent I in a weight
ratio of 100:66 (mix-ture I). An analogous mixture is also
prepared using the conventional adduct curing agent II (mix-
ture II). In both cases, cleaned, 0,8 mm thick steel
sheets are coated -to a thickness of 200 ~m (thickness of the
wet film) wi-th the mix-tures I and II. These metal sheets
are used to de-termine -the properties in respect of lacquer
technology and these properties are compared in Table 3. In :
order -to test the stability towards dilute acetic.acid and ::
alcohol, fur-ther steel shèets are coated -to a layer thickness
of 300 ~m. The corresponding results are compared in
Table L~,
'
.
- 24 - ~ -
'I ' ~ , ' ' ' '
'" " ' ,;
.
,
p~s~
(Proper-ties in respect of lacquer -technology for mixtures I
and II and -the coatings produced)
_
Mixture I II
. . . _ , . . , , , _ _
Gel time for 100 ml
(Tecam appara-tus) >210 mins. 140 mins.
Viscosity of the mixture
(25C) cP ~ 50,000 9,000
Time for drying to -touch¦hours 7 12
Through-curing -time/hours 20 15
Appearance of the film 20/65%
relative humidity good good
Appearance of the film 20/100%
relative humidity good good
Appearance o~ -the film 5/45%
relati~e humidity . good good
Hardness (Persoz)
seconds/7 days 320 345
Erichsen ~l/m/7 days 3 - 5 C 2
Impact cmkg 30-40 ~ 40
Adhesion on sand-blasted
sheet steel good moderate
Stabili-ty to boiling water
(6 hours/96C) good good
~ 72 rJ 72
Table 4
__
(Stabili-ty of -the coatings towards dilute acetic acid and
ethyl alcohol in months
Layer thickness: about 300 ~m on sand-blasted sheet steel,
curing 10 days)
. _ , _ ~ ~ , _, ~
Mixture I II III IV
_~ ~ __ , _ _ ,
Acetic acid, 5%~6 ~12 ~12 1 D
. Acetic acid, 10% ~6 ~12 ~ ~ 1 D
Ethanol, 20% ~ ~12 ~7
Ethanol, 50~0 1-6 A 7-9 D C 1 D _
-- . . , , ,~ , ~. ,,."~ __ _ ~ ~
- 25 -
;3S~IL
Legend: 1-6 A signifies: Film a-ttacked, for example softer
or formation of bubbles 9 from 1~6
months
1 ~ signi~ies: Film destroyed before 1 month
~6 and ~8
signifies: Film intact after 6 and 8 months
respec-tively (test con-tinued)
Mixture III containing~ curing agent III = adduct
(associate) of 4,4'-diamino-3,3-
dimethyl-dicyclohexylmethane and
nonylphenol
Mixture IV containing: curing agent IV = adduct
(associate) of trime-thylhexamethy-
lenediamine and nonylphenol.
r~AI~t~~ ~ tb~ l~s~lt~ ~
If the processing charaoteristics, which are very
important industrially, and the properties in respect of
lacquer technology which are achieved with the coatings are
first compared with the aid of Table 3, the curable mlx-ture I
containing the adduct curing agent I based on 1,4-diamino-2,3-
diphenylbu-tane has a longer po-t life (of ~210 ~inutes) com-
pared with the mixture II containing the adduc-t curing agent
II based on 4,4l-diamino-diphènylmethane and this ~acilitates
easy processing by hand with a brush and roller, for which
there is a great demand in practice.
Some of the other properties in respec-t of lacquer
-~
tec~mology of such coatings are superior to the properties of
coatings which contain curi.ng agents based on conventional
'~.
_ 26 --
.. . . . . . . .
.. . . .
~"': ;' ,' : ,
, : :
S~
aromatic amines. The colour stability of the novel
aclduct curing agent I is significantly be-tter and -this rnakes
it possible, for example, to produce whi-te-pigmented coatings.
In respec-t of the stabili-ty to highly aggressive media
such as dilute organic acids (5/0 st,rength and 10% strength
ace-tic acid) and also 20% and 50% ethyl alcohol, which are a
factor de-termining -the quality in the foods-tuffs sec-tor, -the
novel adduc-t curing agent I shows up very well when compared
with the curing agent based on 4,4'-diaminodiphenylmethane
and is distinc-tly superior to the other conventional curing
agents based on aliphatic and cycloaliphatic polyamines (compar-
ison mixtures III and IV, Table 4).
Example III
(Pre-reaction product which is stable on storage; B-stage)
The resin/curing agent mixture described in Example I
and a suspension prepared from 100 parts by weight of -the same
epoxide resin ~X) and 26.2 parts by weight of 4,4'-diamino-
diphenylmethane, which is intended to enable a comparison to
be made with the state of -the art, are stored at room temp-
erature (RT) and their reactivity and their softenlng range
are checked at specific intervals. Two different experi-
mental methods are used for this purpose:
a) Determination of the gel time at 120C on a thermo-
statically controlled hot-pla-te and
b) Determlnation of the reactivity using the ~ifferential
Thermoanalyser already described above.
In addition to changes in the temperatures for the
, . .
- 27 -
L
melting point, the star-t of reac-tion and -the reac-tion maximum 7
the de-terminati.on of the hea-t of reaction fur-ther liberated
during complete curing of -the pre-reaction products in parti-
cular enables an assessment to be made of the degree of
conversion be~ore and after s-torage of the pre-reac-tion
produc-t.
The values determined ~or the two systems by the
methods mentioned are summarised in Tablë 5.
- 28 -
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,
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_ _ _ .
-- 29 -- .
Evalua-tion of the results
_
According to Example III it is surprisingly possible
by simply grinding the solid amine of -the formula I prepared
according to the invention with the liquid epoxide resin (X~
to obtain pastes which, al-though they show a distinc-t rise in
viscosity af-ter storing ~or a period of days, can still be
applied as a pas-te even after 90 days and have virtually the
same gel time as after storage for 3 days at room temperature.
This is the more surprising because diaminodiphenylmethane,
which because of its chemical structure is considerably less
reactive, under the same conditions results in a paste which
becomes solid after only 3 days storage at room temperatnre.
In accordance with Example I, 34.3 g of 1,4-diamino- ;~
2-p--tolyl~3-phenylbu-tane and 41.2 g of 1,4-diamino-2-(p-
chlorophenyl)-3-(p-methoxyphenyl)-butane are each homogenised,
by means of a triple roll mill, with 100 g of the same epoxide
resin based on bisphenol A, a viscous suspension being obtained.
The characteristics of the mouldings and B-stage resins pre-
pared therefrom are given in Table 6 and 7.
- 30
,
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~ 32 ~
3~
Since they have a lower degree of conversi.on, the
solid and fusible B-s-tage resins ob-tained from the amines pre-
pared according -to the inven-tion and the liquid epoxide resin
based on blsphenol A can be applied more easily than the B-
stage resins ob-tained from diaminodiphenylmethane and the same
epoxide resin under -the same condi-tions.
- 33 -
