Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From sulfur-containing reactant
Reexamination Certificate
2002-01-25
2004-07-06
Sellers, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From sulfur-containing reactant
C525S523000
Reexamination Certificate
active
06759506
ABSTRACT:
The present invention relates to polymercaptopolyamines, to a process for the preparation thereof, to epoxy resin compositions comprising such polymercaptopolyamines and to the use of those compositions.
U.S. Pat. No. 5,143,999 describes mixtures of polyamines and of dithiols derived from polyoxyalkylene glycols as hardeners for epoxy resins. The cured products produced therefrom are distinguished by a high degree of flexibility and good viscoelastic properties combined with good strength and hardness values.
The problem of the present invention was to provide curing agents for epoxy resins which yield cured products having improved resistance to chemicals.
It has now been found that certain polymercaptopolyamines are highly reactive with respect to epoxy resins even at low temperatures and that the cured products obtained therefrom have both improved resistance to chemicals and increased resistance to weathering.
The present invention relates to compounds of formula Ia or Ib,
wherein A is an (n+1)-valent aliphatic, cycloaliphatic, araliphatic or aromatic radical and n is an integer from 0 to 5,
E is an (m+1)-valent aliphatic, cycloaliphatic, araliphatic or aromatic radical and m is an integer from 0 to 3,
X is —O—, —C(═O)O or —CHR
4
—, with R
4
and R
3
together forming an ethylene group,
R
1
and R
2
are, each independently of the other, hydrogen or methyl,
R
3
is hydrogen,
R
5
is a monovalent aliphatic, cycloaliphatic, araliphatic or aromatic radical.
In formula Ia, A can, in principle, be any mono- to hexa-valent epoxy radical. Preference is given to bi-, tri- and tetra-valent radicals.
Examples of aliphatic radicals are ethylene, propylene, tetramethylene, hexamethylene, poly(oxyethylene), poly(oxypropylene), poly(oxytetramethylene), 2-methyl-1,5-pentanediyl, 2,2,4-trimethyl-1,6-hexanediyl, 2,4,4-trimethyl-1,6-hexanediyl and the radicals of aliphatic alcohols after removal of the OH groups, for example the radicals of trimethylolpropane, pentaerythritol and dipentaerythritol.
Cycloaliphatic radicals are, for example, cyclopentyl, cyclohexyl, 1,3-cyclopentylene, 4-methyl-1,3-cyclopentylene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, 4-methyl-1,3-cyclohexylene, 2,5-norbornanediyl, 2,6-norbornanediyl, 7,7-dimethyl-2,5-norbornanediyl, 7,7-dimethyl-2,6-norbornanediyl, cyclohexane-1,3-dimethylene, cyclohexane-1,4-dimethylene, 3-methylene-3,5,5-trimethylcyclohexylene (isophorone), norbornane-2,5-dimethylene, norbornane-2,6-dimethylene, 7,7-dimethylnorbornane-2,5-dimethylene and 7,7-dimethylnorbornane-2,6-dimethylene and the radicals of cycloaliphatic alcohols after removal of the OH groups, for example the radicals of hydrogenated bisphenol A and hydrogenated bisphenol F.
Suitable araliphatic radicals are, for example, benzyl, the radicals of 1,2-, 1,3- and 1,4-bis(hydroxymethyl)benzene, the radicals of 1,2,3-, 1,2,4-, 1,2,5- and 1,3,5-tris(hydroxymethyl)benzene and the radicals of bis(hydroxymethyl)naphthalene. Examples of aromatic radicals are phenyl, naphthyl, the radicals of bisphenols, for example bisphenol A, bisphenol F and dihydroxybiphenyl, and the radicals of phenol novolaks and cresol novolaks.
Preference is given to compounds of formula Ia wherein X is —O— and A is a bivalent radical of a bisphenol or of a cycloaliphatic diol, the radical of a phenol novolak or cresol novolak, the bi- to tetra-valent radical of an isocyanate/polyol adduct or the tri- to hexa-valent radical of a tri- to hexa-functional aliphatic polyol.
Special preference is given to compounds of formula Ia wherein X is —O— and A is a bivalent radical of formula
the radical of a phenol novolak or cresol novolak, a trivalent radical of formula
or the tetravalent radical of formula
R
5
in formulae Ia and Ib is preferably C
1
-C
20
alkyl, C
5
-C
12
cycloalkyl, C
6
-C
10
aryl or C
7
-C
12
aralkyl, each of which is unsubstituted or substituted by one or more amino groups, hydroxyl groups, C
1
-C
8
alkoxy groups or halogen atoms.
Alkyl groups that are suitable as R
5
are, for example, methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, sec-butyl, tert-butyl and the various isomers of pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl groups.
Cycloalkyl is preferably C
5
-C
8
cycloalkyl, especially C
5
- or C
6
-cycloalkyl. Examples include cyclopentyl, methylcyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.
Aralkyl contains preferably from 7 to 12 carbon atoms and especially from 7 to 10 carbon atoms and may be, for example, benzyl, phenethyl, 3-phenylpropyl, &agr;-methylbenzyl, 4-phenylbutyl and &agr;,&agr;-dimethylbenzyl.
Aryl groups are, for example, phenyl, tolyl, mesityl, isityl, naphthyl and anthryl.
Preference is given to compounds of formulae Ia and Ib wherein R
5
is C2-C
10
alkyl, C
2
-C
10
aminoalkyl, phenyl, benzyl, cyclohexyl or a radical of formula H
2
N—Z—CH
2
—NH—, wherein Z is a bivalent cycloaliphatic, araliphatc or aromatic radical or a radical of formula —(CH
2
CH
2
NH)
k
—CH
2
—, wherein k is 2 or 3.
Suitable radicals Z are, for example, the bivalent radicals mentioned for A hereinbefore.
Special preference is given to compounds of formulae Ia and Ib wherein R
5
is n-butyl, n-octyl, cyclohexyl, benzyl, 2-aminoethyl, 4-(aminomethyl)pentyl, 5-amino-2-methylpentyl, 3-dimethylaminopropyl, 3-methylaminopropyl, 4-aminocyclohexyl or a radial of formula —CH
2
CH
2
NHCH
2
CH
2
NH
2
,
Preference is given also to compounds of formula Ia or Ib wherein X is O— and R
1
and R
3
are hydrogen.
The compounds of formula Ia can be prepared in accordance with known methods from the epoxy compounds of formula IIa:
wherein A, X, R
1
, R
3
and n are as defined hereinbefore.
In such methods, the epoxy compound of formula IIa is, in a first reaction step, converted by reaction with thiourea or an alkali-metal or ammonium thiocyanate, preferably potassium thiocyanate, into the episulfide of formula IIIa
the thiourea or thiocyanate advantageously being used in an amount such that there are from 0.8 to 1.2 equivalents of sulfur for one epoxy equivalent.
The reaction can be carried out in aprotic or protic organic solvents or mixtures thereof. Preference is given to alcohols, for example methanol and ethanol, and aromatic hydrocarbons, for example toluene and xylene. The addition of co-solvents, for example ethers or carboxylic acids, can speed up the reaction.
The reaction can be carried out at room temperature and also at elevated temperature; the preferred reaction temperature is from 60 to 100° C.
The episulfide of formula IIIa can be isolated by separating off the by-products by means of filtration, extraction, phase separation and subsequent concentration by evaporating off the solvent.
It is also possible, however, for the episulfide of formula IIIa to be further processed directly, in the form of the crude product in solution, without separating off the by-products.
The episulfide of formula IIIa is then dissolved in an aprotic or protic organic solvent and, under inert gas (argon or nitrogen), reacted with the amine R
5
—NH—R
2
, the amount of the amine R
5
—NH—R
2
preferably being so selected that there are from 1 to 10 amine groups for one episulfide group. Preferred solvents are alcohols (e.g. methanol, ethanol, tert-butanol) and aromatic hydrocarbons, for example toluene and xylene
Preferably, the amine R
1
—NH
2
is also used in the form of a solution in one of the above-mentioned organic solvents.
The reaction is advantageously carried out at elevated temperature, preferably at from 40° C. to 120° C.
The compounds of formula Ia according to the invention can be isolated by distilling off the solvent under reduced pressure. The excess amine R
5
—NH—R
2
can then likewise be removed by distillation at elevated temperature. In a particular embodiment of the invention, the amine R
5
—NH—R
2
is used as co-hardener, in which case separation of the product of formula Ia and the amine R
5
—NH—R
2
is not necessary; rather, the reaction product can be used as a hardener for ep
Fischer Walter
Frischinger Isabelle
Gabutti Claudio A
Wiesendanger Rolf
Huntsman Advanced Materials Americas Inc.
Levato Tiffany A.
Neuman Kristin H.
Proskauer Rose LLP
Sellers Robert
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