Epoxy resin and polythiol composition

Epoxy resin compositions which contain (1) an epoxy resin which has two or more epoxy groups in its molecule, (2) a polythiol compound which has two or more thiol groups in its molecule and (3) an accelerator which is (i) a solid dispersion-type amine adduct latent curing accelerator or (ii) the product of a reaction between a compound which contains one or more isocyanate groups in its molecule and a compound which has at least one primary and/or secondary amino group in its molecule, exhibit excellent curability at relatively low heating temperatures as well as a long working life.

FIELD OF THE INVENTION 
The present invention relates to a polythiol epoxy resin compositions which 
cure rapidly at relatively low heating temperatures, provide a strong 
adhesive strength and long working life, and thus are suitable for 
processing. The present invention also relates to cured epoxy resins 
prepared by heating such compositions. 
DISCUSSION OF THE BACKGROUND 
Epoxy resin compositions which use polythiol as a curing agent and a liquid 
tertiary amine as an accelerator are known as low-temperature, 
rapid-curing epoxy resin compositions which may be cured at -20.degree. C. 
to 0.degree. C., and these are widely used in adhesives, sealing agents, 
casting materials and the like. 
However, such epoxy resin compositions are disadvantageous in that their 
pot life is very short, usually a few seconds to a few minutes after 
mixing, and thus there is not enough time for mixing, defoaming and 
application. Also, since the user must prepare a new composition each 
time, the working efficiency is lowered, and since the excess composition 
cannot be preserved it must be disposed of, which is disadvantageous from 
the point of view of conservation of resources and environmental problems. 
Thus, it has been desired to develop a polythiol epoxy resin composition 
which has a sufficiently long working life and a good working efficiency. 
Nevertheless, the commercially available epoxy resins which contain thiol 
compounds generally have a poor shelf life, and it is difficult to 
increase the working life of epoxy resin compositions when used with thiol 
curing agents. 
As a method to solve such problems, a method has been investigated in which 
an acid anhydride or mercapto organic acid is added to the resin as a 
retarder to lengthen the working life thereof (Japanese laid-open patent 
application S61-159417), but this method cannot be said to be sufficiently 
satisfactory. 
On the other hand, examples of a thiol compound obtained by an 
esterification reaction between a polythiol and a mercapto organic acid 
which is used as a curing agent for epoxy resins are described in Japanese 
laid-open patent application S41-7236, Japanese laid-open patent 
application S42-26535, Japanese laid-open patent application S47-32319, 
Japanese laid-open patent application S46-732 and Japanese laid-open 
patent application S60-21648, but the accelerators used in these epoxy 
resin compositions are liquid amines, etc. Also, the compositions using 
these liquid amines, etc. have a very short working life of from a few 
minutes to a few dozen minutes, which is a serious disadvantage. 
Thus, there remains a need for polythiol epoxy resin compositions which 
exhibit good curability at relatively low temperatures and also exhibit a 
long working life. 
SUMMARY OF THE INVENTION 
Accordingly, it is one object of the present invention to provide novel 
polythiol epoxy resin compositions which exhibit good curability at 
relatively low heating temperatures. 
It is another object of the present invention to provide novel polythiol 
epoxy resin compositions which exhibit a long working life. 
It is another object of the present invention to provide novel polythiol 
epoxy resin compositions which exhibit good adhesive strength. 
It is another object of the present invention to provide cured compositions 
obtained by heating such polythiol epoxy resin compositions. 
These and other objects, which will become apparent during the following 
detailed description have been achieved by the inventors' discovery that a 
polythiol epoxy resin composition which has a sufficiently long working 
life, cures rapidly at relatively low heating temperatures, and also has a 
strong adhesive strength may be obtained by using as the curing agent a 
polythiol compound which has two or more thiol groups in its molecule and 
using as the curing accelerator (i) a solid dispersion-type amine adduct 
latent curing accelerator or (ii) the product of a reaction between a 
compound which contains one or more isocyanate groups in its molecule and 
a compound which has at least one primary and/or secondary amino group in 
its molecule. 
That is, the present invention relates to an epoxy resin composition which 
contains (1) an epoxy resin which has two or more epoxy groups in its 
molecule, (2) a polythiol compound which has two or more thiol groups in 
its molecule and (3) an accelerator which is (i) a solid dispersion-type 
amine adduct latent curing accelerator or (ii) a compound obtained as the 
product of a reaction between a compound which contains one or more 
isocyanate groups in its molecule and a compound which has at least one 
primary and/or secondary amino group in its molecule.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The epoxy resin (1) to be used according to the present invention may be 
any one which has an average of two or more epoxy groups per molecule. 
Examples thereof include polyglycidyl ethers which are obtained by 
reacting a polyhydric phenol such as bisphenol A, bisphenol F, bisphenol 
AD, catechol, resorcinol, etc. or a polyhydric alcohol such as glycerin or 
polyethylene glycol, etc. with epichlorohydrin; glycidyl ether esters 
which are obtained by reacting a hydroxycarboxylic acid such as 
p-hydroxybenzoic acid or .beta.-hydroxynaphthoic acid with 
epichlorohydrin; polyglycidyl esters which are obtained by reacting a 
polycarboxylic acid such as phthalic acid or terephthalic acid with 
epichlorohydrin; as well as epoxidized phenolic novolac resins, epoxidized 
cresol novolac resins, epoxidized polyolefins, cyclic aliphatic epoxy 
resins, and also urethane modified epoxy resins and the like, but it is 
not limited to these examples. 
The polythiol compound (2) to be used according to the present invention is 
a thiol compound which has two or more thiol groups in its molecule, and 
which does not require the use of a basic substance for its production, 
such as a thiol compound obtained by the esterification reaction of a 
mercapto organic acid with a polythiol such as, for example, 
trimethylolpropane tris-(thioglycolate), pentaerythritol 
tetrakis-(thioglycolate), ethyleneglycol dithioglycolate, 
trimethylolpropane tris-(.beta.thiopropionate), pentaerythritol 
tetrakis-(.beta.-thiopropionate), dipentaerythritol 
poly(.beta.-thiopropionate), etc. 
In the same manner, thiol compounds with two or more thiol groups in their 
molecules for which basic substances are used as reaction catalysts during 
the steps of their production may be used, when combined with a 
dealkalizing treatment to reduce the alkali metal ion concentration to 50 
ppm or less, preferably 10 ppm or less, based on the total weight of the 
thiol compound. Such thiol compounds include alkyl polythiol compounds 
such as 1,4-butanedithiol, 1,6-hexanedithiol and 1,10-decanedithiol; 
terminal thiol group-containing polyethers, terminal thiol 
group-containing polythioethers, thiol compounds obtained by a reaction of 
an epoxy compound with hydrogen sulfide; and thiol compounds containing a 
terminal thiol group which are obtained by a reaction of a polythiol 
compound with an epoxy compound. 
As the method for dealkalization treatment of the polythiol compounds 
prepared using a basic substance as a reaction catalyst may be mentioned, 
for example, a method in which the thiol compound to be treated is 
dissolved in an organic solvent such as acetone or methanol, and an acid 
such as dilute hydrochloric acid or dilute sulfuric acid is added thereto 
for neutralization to a pH of 5.0 to 7.1, preferably about 6.5 to 7.0, 
after which extraction and washing are carried out for desalting. 
Alternative methods include a method of adsorption using anion-exchange 
resin, a method of purification by distillation, etc., but dealkalization 
is not limited to these methods. 
The solid dispersion-type amine adduct latent curing accelerator (3)(i) to 
be used according to the present invention is the product of a reaction 
between (b) an amine compound and (a) an epoxy compound which is a solid, 
insoluble in the epoxy resin at room temperature, and which functions as 
an accelerator by becoming soluble upon heating as described in U.S. Pat. 
Nos. 4,542,202, 4,546,155, Japanese Patent publication (KOUKOKU) HEI 
5-4409 and Japanese Patent Publication (KOUKOKU) HEI 5-57690; this also 
includes those reaction products whose surfaces have been treated with an 
isocyanate compound or acidic compound, etc. as described in U.S. Pat. No. 
4,833,226. 
As examples of the epoxy compound (a) to be used as a starting material for 
the production of the latent curing accelerator (3)(i) which is used 
according to the present invention may be mentioned polyfunctional epoxy 
compounds such as polyglycidyl ethers which are obtained by reacting a 
polyhydric phenol such as bisphenol A, bisphenol F, catechol, resorcinol, 
etc. or a polyhydric alcohol such as glycerin or polyethylene glycol, etc. 
with epichlorohydrin; glycidyl ether esters which are obtained by reacting 
a hydroxycarboxylic acid such as p-hydroxybenzoic acid or 
3-hydroxynaphthoic acid with epichlorohydrin; polyglycidyl esters which 
are obtained by reacting a polycarboxylic acid such as phthalic acid or 
terephthalic acid with epichlorohydrin; glycidylamine compounds which are 
obtained by reacting 4,4'-diaminodiphenylmethane, m-aminophenol or the 
like with epichlorohydrin; and epoxidized phenolic novolac resins, 
epoxidized cresol novolac resins, epoxidized polyolefins, as well as 
monofunctional epoxy compounds such as butyl glycidyl ethers, phenyl 
glycidyl ethers, glycidyl methacrylate and the like, but the epoxy 
compound is not limited to these examples. 
The amine compound (b) to be used as a starting material for the production 
of the latent curing accelerator (3)(i) which is used according to the 
present invention may be any one which has in its molecule one or more 
active hydrogens capable of an addition reaction with an epoxy group, as 
well as one or more substituents selected from primary, secondary and 
tertiary amino groups. Examples of such amine compounds are given below, 
but the amine compounds are not limited thereto. 
It may be, for example, an aliphatic amine such as diethylenetriamine, 
triethylenetetraamine, n-propylamine, 2-hydroxyethylaminopropylamine, 
cyclohexylamine, 4,4'-diamino-dicyclohexylmethane; an aromatic amine 
compound such as 4,4'-diaminodiphenylmethane, 2-methylaniline, etc.; or a 
nitrogenous heterocyclic compound such as 2-ethyl-4-methylimidazole, 
2-methylimidazole, 2-ethyl-4-methylimidazoline, 2,4-dimethylimidazoline, 
piperidine, piperazine, etc. 
Furthermore, of these compounds, particularly those which have tertiary 
amino groups in their molecules are materials which will provide latent 
curing accelerators (3(i)) with excellent accelerating properties, and 
examples of such compounds include, for example, amine compounds such as 
dimethylaminopropylamine, diethylaminopropylamine, 
di-npropylaminopropylamine, dibutylaminopropylamine, 
dimethylaminoethylamine, diethylaminoethylamine, N-methylpiperazine, etc.; 
primary and secondary amines which have a tertiary amino group in their 
molecules, such as imidazole compounds like 2-methylimidazole, 
2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, etc.; and 
alcohols, phenols, thiols, carboxylic acids, hydrazides, etc. which have a 
tertiary amino group in their molecules, including 2-dimethylaminoethanol, 
1-methyl-2-dimethylaminoethanol, 1-phenoxymethyl-2-dimethylaminoethanol, 
2-diethylaminoethanol, 1-butoxymethyl-2-dimethylaminoethanol, 
1-(2-hydroxy-3-phenoxypropyl)-2-methylimidazole, 
1-(2-hydroxy-3-phenoxypropyl)-2-ethyl-4-methylimidazole, 
1-(2-hydroxy-3-butoxypropyl)-2-methylimidazole, 
1-(2-hydroxy-3-butoxypropyl)-2-ethyl-4-methylimidazole, 
1-(2-hydroxy-3-phenoxypropyl)-2-phenylimidazoline, 
1-(2-hydroxy-3-butoxypropyl)-2-methylimidazoline, 
2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, 
N-.beta.-hydroxyethylmorpholine, 2-dimethylaminoethanethiol, 
2-mercaptopyridine, 2-mercaptobenzoimidazole, 2-mercaptobenzothiazole, 
4-mercaptopyridine, N,N-dimethylaminobenzoic acid, N,N-dimethylglycine, 
nicotinic acid, isonicotinic acid, picolinic acid, N,N-dimethylglycine 
hydrazide, N,N-dimethylpropionic acid hydrazide, nicotinic acid hydrazide, 
isonicotinic acid hydrazide, etc. 
In order to further improve the shelf life of the epoxy resin composition 
according to the present invention, when the addition reaction is 
conducted with the above mentioned epoxy compound and amine compound to 
produce the latent curing accelerator (3)(i) to be used according to the 
present invention, (c) an active hydrogen compound having two or more 
active hydrogens in its molecule may be added thereto as a third 
component. Examples of such an active hydrogen compound are given below, 
but the active hydrogen compound is not limited thereto. 
The active hydrogen compound (c) may be, for example, a polyhydric phenol 
such as bisphenol A, bisphenol F, bisphenol S, hydroquinone, catechol, 
resorcinol, pyrogallol, phenolic novolac resin, etc.; a polyhydric alcohol 
such as trimethylolpropane, etc.; a polyhydric carboxylic acid such as 
adipic acid, phthalic acid, etc.; or 1,2-dimercaptoethane, 
2-mercaptoethanol, 1-mercapto-3-phenoxy-2-propanol, mercaptoacetic acid, 
anthranilic acid, lactic acid, etc. 
Representative examples are given below of the isocyanate compound to be 
used as the surface treatment agent for the production of the latent 
curing accelerator (3)(i) used according to the present invention, but the 
isocyanate compound is not limited thereto these examples. 
The isocyanate comound may be, for example, a monofunctional isocyanate 
compound such as n-butyl isocyanate, isopropyl isocyanate, phenyl 
isocyanate, benzyl isocyanate, etc.; a polyfunctional isocyanate compound 
such as hexamethylene diisocyanate, tolylene diisocyanate, 1,5-naphthylene 
diisocyanate, diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, 
xylylene diisocyanate, p-phenylene diisocyanate, 1,3,6-hexamethylene 
triisocyanate, bicycloheptane triisocyanate, etc.; and also terminal 
isocyanate-containing compounds obtained by reactions of these 
polyfunctional isocyanate compounds and active hydrogen compounds may be 
used, examples of which include a terminal isocyanate-containing addition 
reaction product obtained by a reaction of tolylene diisocyanate with 
trimethylolpropane, and a terminal isocyanate-containing addition reaction 
product obtained by a reaction of tolylene diisocyanate with 
pentaerythritol. 
The acidic substance to be used as the surface treatment agent for the 
production of the latent curing accelerator (3)(i) used according to the 
present invention may be a gaseous or liquid inorganic or organic acid, 
and representative examples thereof are given below; however, the acidic 
substance is not limited to these examples. 
The acidic substance may be, for example, carbon dioxide, sulfur dioxide, 
sulfuric acid, hydrochloric acid, oxalic acid, phosphoric acid, acetic 
acid, formic acid, propionic acid, adipic acid, caproic acid, lactic acid, 
succinic acid, tartaric acid, sebacic acid, p-toluenesulfonic acid, 
salicylic acid, boric acid, tannic acid, alginic acid, polyacrylic acid, 
polymethacrylic acid, phenol, pyrogallol, phenol resin, resorcin resin, 
etc. 
The latent curing accelerator (3)(i) to be used according to the present 
invention may be easily obtained mixing the above mentioned components (a) 
an epoxy compound and (b) an amine compound, or (a) an epoxy compound, (b) 
an amine compound and (c) an active hydrogen compound, and reacting them 
at from room temperature to 200.degree. C., and then solidifying and 
crushing the product thereof, or by reacting them in a solvent such as 
methyl ethyl ketone, dioxane, tetrahydrofuran or the like, removing the 
solvent, and then crushing the solid fraction thereof. Furthermore, the 
surface treatment of these latent curing accelerators may be carried out 
by contacting them with any of the above mentioned isocyanate compounds or 
acidic compounds in a solvent such as methyl ethyl ketone, toluene, etc. 
or with no solvent. 
Commercially available representative examples of the above mentioned solid 
dispersion-type amine adduct latent curing accelerator (3)(i) are given 
below, but it is not limited to these examples. For example, mention may 
be made of "Ajicure PN-231 (trademark, Ajinomoto, Inc.), "Ajicure PN-H" 
(trademark, Ajinomoto, Inc. ), "Ajicure MY-24" (trademark, Ajinomoto, 
Inc.), "Hardener X-3661S" (trademark, A.C.R. Co., Ltd.), "Hardener 
X-3670S" (trademark, A.C.R. Inc.), "Novacure HX-3742" (trademark, Asahi 
Chemical Industry Co., Ltd.), "Novacure HX-3721" (trademark, Asahi 
Chemical Industry Co., Ltd.), etc. 
The compound to be used according to the present invention which is 
obtained by a reaction between a compound which contains one or more 
isocyanate groups in its molecule and a compound which has at least one 
primary and/or secondary amino group in its molecule (3)(ii), may be 
obtained by reacting the isocyanate with a compound which has a primary 
and/or secondary amino group in an organic solvent such as 
dichloromethane. 
As the above mentioned compound which contains one or more isocyanate 
groups in its molecule may be mentioned, for example, n-butyl isocyanate, 
isopropyl isocyanate, 2-chloroethyl isocyanate, phenyl isocyanate, 
p-bromophenyl isocyanate, m-chlorophenyl isocyanate, o-chlorophenyl 
isocyanate, p-chlorophenyl isocyanate, 2,5-dichlorophenyl isocyanate, 
3,4-dichlorophenyl isocyanate, 2,6-dimethylphenyl isocyanate, 
o-fluorophenyl isocyanate, p-fluorophenyl isocyanate, m-tolyl isocyanate, 
p-tolyl isocyanate, o-trifluoromethylphenyl isocyanate, 
m-trifluoromethylphenyl isocyanate, benzyl isocyanate, hexamethylene 
diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 
1,5-naphthylene diisocyanate, diphenylmethane-4,4'-diisocyanate, 
2,2-dimethyldiphenylmethane-4,4'-diisocyanate, tolidene diisocyanate, 
isophorone diisocyanate, xylene diisocyanate, 
1,3-bis(isocyanatomethyl)cyclohexane, p-phenylene diisocyanate, 
1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, 
tris-(3-isocyanato-4-methylphenyl) isocyanurate, tris-(6-isocyanatohexyl) 
isocyanurate, etc., but the compound is not limited to these examples. 
As the compound which has at least one primary and/or secondary amino group 
in its molecule and which reacts with the isocyanate may be mentioned, for 
example, dimethylamine, diethylamine, di-n-propylamine, di-n-butylamine, 
di-n-hexylamine, di-n-octylamine, di-n-ethanolamine, 
dimethylaminopropylamine, diethylaminopropylamine, morpholine, piperidine, 
2,6-dimethylpiperidine, 2,2,6,6-tetramethylpiperidine, piperazine, 
pyrrolidine, benzylamine, N-methylbenzylamine, cyclohexylamine, 
m-xylylenediamine, 1,3-bis(aminomethyl)cyclohexane, isophoronediamine, 
N-aminoethylpiperazine, 2-methylimidazole, 2-ethyl-4-methylimidazole, 
2-undecylimidazole, 2-phenylimidazole, 1,1-dimethylhydrazine, etc., but 
the compound is not limited to these examples. 
In addition, as the accelerator may be used a solid dispersion-type latent 
curing accelerator, such as the one described in Japanese Patent 
Application Publication HEI 3-296525 which is obtained by reacting an 
epoxy resin having two or more epoxy groups in its molecule as a third 
ingredient during a reaction with N,N-dialkylaminoalkylamine, an amine 
having an active hydrogen in its molecule and having a cyclic structure 
which includes one or two nitrogen atoms, and a diisocyanate. 
Commercially available dispersion-type latent curing accelerators include 
"Fujicure FXE-1000" (trademark, Fuji Chemical Industry Co., Ltd.), 
"Fujicure FXR-1030" (trademark, Fuji Chemical Industry Co., Ltd.), etc. 
The mixing ratio of the epoxy resin (1) and polythiol compound (2) in the 
epoxy resin composition according to the present invention is such that 
the ratio of epoxy equivalents to thiol equivalents is 0.5-1.5, preferably 
0.75 to 1.3, and the amount to be added of the solid dispersion type 
latent curing accelerator (3)(i) or the compound obtained by a reaction of 
a compound which contains one or more isocyanate groups in its molecule 
with a compound which has at least one primary and/or secondary amino 
group in its molecule (3)(ii), is 0.1-10, preferably 0.5-5, parts by 
weight of (3)(i) or (3)(ii) to 100 parts by weight of the epoxy resin. 
As necessary, any number of additives may be added to the epoxy resin 
composition according to the present invention, including fillers, 
diluting agents, solvents, pigments, flexibilizer, coupling agents, 
anti-oxidants, and the like. 
If an isocyanate group-containing compound is used as an additive, then the 
adhesive strength may be improved without significantly impairing the 
curability of the resin. Such isocyanate-containing compounds to be used 
are not particularly limited, and representative examples thereof include 
n-butyl isocyanate, isopropyl isocyanate, 2-chloroethyl isocyanate, phenyl 
isocyanate, p-chlorophenyl isocyanate, benzyl isocyanate, hexamethylene 
diisocyanate, 2-ethylphenyl isocyanate, 2,6-dimethylphenyl isocyanate, 
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,5-naphthylene 
diisocyanate, diphenylmethane-4,4'-diisocyanate, tolidine diisocyanate, 
isophorone diisocyanate, xylylene diisocyanate, paraphenylene 
diisocyanate, 1,3,6-hexamethylene triisocyanate, bicycloheptane 
triisocyanate, etc. 
The amount of the isocyanate group-containing compound to be added to the 
epoxy resin composition according to the present invention is in the range 
of 0.1-20, preferably 0.5 to 10, parts by weight to 100 parts by weight 
of the epoxy resin. 
The present epoxy resin compositions may be cured to form cured articles by 
simply heating the epoxy resin composition. The degree of heating may vary 
depending on the cure time deemed acceptable. Generally, the composition 
will be cured at a temperature of 40.degree. C. to 200.degree. C., 
preferably 60.degree. C. to 150.degree. C. Thus, the present compositions 
can be cured to form, e.g., cast articles or adhesive layers. 
Other features of the invention will become apparent in the course of the 
following descriptions of exemplary embodiments which are given for 
illustration of the invention and are not intended to be limiting thereof. 
EXAMPLES 
Method of Evaluation 
Shelf life: The prepared epoxy resin composition was poured into a 50 cc 
glass sampling bottle, and measurement was taken of the time required for 
the initial viscosity to double when measured at 25.degree. C. using a 
B-type viscosimeter. 
Working life: The prepared epoxy resin composition was poured into a 50 cc 
glass sampling bottle, and measurement was taken of the time required for 
the flowability to disappear at 25.degree. C. 
Viscosity: Measurement was made based on JIS K-6833. 
Gel time: Measurement was made using a Yasuda gel timer. 
Tensile shear adhesive strength: A sample prepared based on JIS K-6850 was 
cured at a specific temperature and for a specific time, and the tensile 
shear adhesive strength was measured using a Tensilon Universal Testing 
Machine (Tensilon UTM-5T, product of Toyo Seiki, Inc. 
Measuring temperature: 25.degree. C. 
Tension speed: 1 mm/min 
T-peel adhesive strength: A sample prepared based on JIS K6854 was cured at 
a specific temperature and for a specific time, and the tensile shear 
adhesive strength was measured using a Tensilon Universal Testing Machine 
(Tensilon RTM-500, product of Orientech, Inc.). 
Measuring temperature: 25.degree. C. 
Tension speed: 50 mm/min 
Alkali metal ion concentration: Assay was made according to the atomic 
absorption method, using a flame spectrophotometer (Hitachi Model 180-50). 
The names of the materials used in the Examples are as follows. 
(1) Epoxy resin 
"EP-828" (trade name, Yuka Shell Epoxy Co.) Bisphenol A-type epoxy resin 
with epoxy equivalents 184-194 "EP-152" (trade name, Yuka Shell Epoxy Co.) 
Phenolic novolac-type epoxy resin with epoxy equivalents 172-178 
"EP-154" (trade name, Yuka Shell Epoxy Co.) 
Phenolic novolac-type epoxy resin with epoxy equivalents 176-180 
(2) Polythiol compound 
"TMTP" (trade name, Yodo Kagaku Co.) 
Trimethylolpropane tris(.beta.-thiopropionate) 
K.sup.+ &lt;0.5 ppm, Na.sup.+ &lt;2.9 ppm 
"TMTP" (trade name, Yodo Kagaku Co.) 
Trimethylolpropane tris(.beta.-thioglycolate) 
"PETG" (trade name, Yodo Kagaku Co.) 
Pentaerythritol tetrakis(thioglycolate) 
"PETP" (trade name, Yodo Kagaku Co.) 
Pentaerythritol tetrakis(.beta.-thiopropionate) 
Preparation 1 
A 100 g portion of the thiol-type curing agent "Epomate QX-12" (trade name, 
Yuka Shell Co.) was placed in a 1 liter Erlenmeyer flask, and 500 ml of 
acetone was added thereto for dissolution. The solution exhibited a strong 
alkalinity on pH 20 test paper. Concentrated hydrochloric acid was added 
dropwise to the solution while stirring to adjust the pH of the solution 
to weak acidity, and then the solvent was distilled off under reduced 
pressure. To the residue was added 500 ml of distilled water, and 
extraction was performed 3 times with 500 ml of chloroform. Anhydrous 
magnesium sulfate was added to the organic layer and the mixture was 
allowed to stand overnight, after which the magnesium sulfate was filtered 
off and the filtrate was concentrated under reduced pressure to obtain 
purified QX-12. The alkali metal ion concentration of this substance was: 
K.sup.+ =11.2 ppm and Na.sup.+ =1420 ppm prior to the dealkalization 
treatment, but fell to K.sup.+ =0.5 ppm or less and Na.sup.+ =3.2 ppm 
after dealkalization treatment. 
Preparation 2 
A 20 g portion of "Epomate QX-12" was placed in a 300 ml Erlenmeyer flask, 
and 200 ml of methanol was added thereto for dissolution. To this solution 
was added 20 g of the cation exchange resin "Daia-ion PK216H" (product of 
Mitsubishi Kasei, Inc.), and the mixture was stirred for 3 hours. The ion 
exchange resin was then filtered off, and the filtrate was concentrated 
under reduced pressure to obtain purified QX-12. The alkali metal ion 
concentration of this substance was K.sup.+ =2.2 ppm and Na.sup.+ =7.9 
ppm. 
Preparation 3 
To a 500 ml three neck flask equipped with a dropping funnel were added 50 
g of phenyl isocyanate and 200 ml of dichloromethane, and 25 g of 
1,1-dimethylhydrazine was added dropwise thereto while stirring on ice. 
After dropping, the mixture was returned to room temperature and stirred 
for 3 hours, after which the dichloromethane was distilled off under 
reduced pressure to obtain a white, solid crude product. The obtained 
crude product was washed with 200 ml of petroleum ether to obtain 72 g 
(96% yield) of N-phenyl-N',N'dimethylaminourea. 
EXAMPLE 1 
To a mixture prepared by adding 1 part by weight of "Ajicure PN-H" to 10 
parts by weight of the bisphenol A-type epoxy resin "EP828" (trade name, 
Yuka Shell Co.) at room temperature was added 90 parts by weight of the 
purified QX-12 obtained in Preparations 1 and 2, and this was mixed at 
room temperature to obtain epoxy resin compositions (i) and (ii). The 
working life for both compositions (i) and (ii) was 3 hours. Also, the gel 
time for composition (ii) at 60.degree. C. was 925 seconds. 
Comparison Example 1 
Epoxy resin composition (iii) was obtained in the same manner as in Example 
1, except that non-dealkalinized "Epomate QX-12" was used as the polythiol 
compound. The working life for composition (iii) was 3 minutes. 
EXAMPLES 2-5 
Epoxy resin compositions (iv)-(vii) were prepared using "EP828" as the 
epoxy resin, "TMTP" (trimethylolpropane tris(.beta.-thiopropionate), trade 
name of Yodo Kagaku Co. K.sup.+ : &lt;0.5 ppm, Na.sup.+ : 2.9 ppm) as the 
polythiol compound, and the substances shown in Table 1 as the solid 
dispersion-type amine adduct latent curing accelerators. The properties of 
compositions (iv)-(vii) are shown in Table 1. 
Comparison Examples 2-7 
Epoxy resin compositions (viii)-(xiii) were prepared in the same manner as 
in Examples 2-5, except that, instead of the solid dispersion-type amine 
adduct latent curing accelerators were used the liquid accelerators 
"Epomate B-02" (adduct of 
3,9-bis(aminopropyl)-2,4,8,10-tetraoxaspiro-[5,5]-undecane and 
butylglycidyl ether (liquid), trade name of Yuka Shell Co.), "2E4MZ" 
(2-ethyl-4-methylimidazole, trade name of Shikoku Kasei) and "DMP-30" 
(2,4,6-tris(dimethylaminomethyl)phenol). The properties of compositions 
(viii)-(xiii) are shown in Table 1. The present invention is characterized 
by providing a long working life and allowing a short curing time in 
comparison to the examples in which liquid or soluble amine compounds were 
used as the accelerators. 
TABLE 1 
__________________________________________________________________________ 
Initial 
Gel Time 
Epoxy Epoxy Resin 
Thiol Compound 
Curing Accelerator 
Viscosity 
(second) Working 
Composition 
/Parts /Parts /Parts (poise) 
60.degree. C. 
80.degree. C. 
Life 
__________________________________________________________________________ 
Example 2 
iv EP828/100 
TMTP/74 Ajicure PN-H/1 
13.0 1398 314 7 days 
Example 3 
v EP828/100 
TMTP/74 Ajicure MY-24/1 
13.0 485 144 8 hrs 
Example 4 
vi EP828/100 
TMTP/74 Novacure HX-3742/3 
13.0 1772 380 7 days 
Example 5 
vii EP828/100 
TMTP/74 Novacure HX-3721/1 
13.0 2598 666 1 day 
Comparison 2 
viii EP828/100 
TMTP/74 TDAMP*/1 13.0 -- 275 25 min 
Comparison 3 
ix EP828/100 
TMTP/60 m-Xylenediamine/4 
15.0 -- &gt;7200 17 hrs 
Comparison 4 
x EP828/100 
TMTP/60 Ethanolamine/5 
15.0 -- 2478 30 min 
Comparison 5 
xi EP828/100 
TMTP/60 Epomate B-02/10 
18.0 -- 3729 4 hrs 
Comparison 6 
xii EP828/100 
TMTP/74 2E4MZ/5 14.0 -- 451 8 hrs 
Comparison 7 
xiii EP828/100 
TMTP/74 DMP-30/1 13.0 -- 275 25 
__________________________________________________________________________ 
min 
*TDAMP: Tris(dimethylaminomethyl)phenol 
EXAMPLE 6 
To 100 parts by weight of "EP828" was added 2 parts by weight of "Ajicure 
PN-H" and these were mixed at room temperature, after which "TMTP" was 
added thereto and the components were mixed while defoaming to prepare 
epoxy resin compositions (xiv)-(xviii). The properties of each of the 
compositions and their properties after curing at 80.degree. C. for 20 
minutes are shown in Table 2. 
TABLE 2 
______________________________________ 
Epoxy 
Composition xiv xv xvi xvii xviii 
______________________________________ 
EP828 (Parts) 100 100 100 100 100 
TMTP (Parts) 74 66 59 52 44 
Ajicure (Parts) 2 2 2 2 2 
PN-H 
Gel Time (sec) 213 204 184 175 169 
80.degree. C. 
Working Life 3 days 3 days 
3 days 
4 days 
4 days 
Tensile Shear 
(kgf/ 210 209 186 145 76 
Adhesive cm.sup.2) 
Strength 
T-peel (kgf/ 1.0 1.1 4.8 8.1 8.9 
Adhesive 25 mm) 
Strength 
______________________________________ 
EXAMPLE 7 
To 100 parts by weight of "EP828" was added 3 parts by weight of "Ajicure 
PN-H", and these were mixed at room temperature, and then 74 parts by 
weight of "TMTP" was added thereto and the components were mixed while 
defoaming, after which "MR-200" (diphenylmethane-4,4'-diisocyanate: 
product of Nippon Polyurethane, Inc.) was added thereto, to prepare epoxy 
resin compositions (xix)-(xxii). The gel times at 80.degree. C. and the 
shear adhesive strengths after curing at 80.degree. C. for 20 minutes for 
each of the compositions are shown in Table 3. 
TABLE 3 
______________________________________ 
Epoxy 
Composition xix xx xxi xxii 
______________________________________ 
EP828 (Parts) 100 100 100 100 
TMTP (Parts) 74 74 74 74 
Ajicure PN-H 
(Parts) 3 3 3 3 
MR-200 (Parts) 0 1 4 10 
Gel Time 80.degree. C. 
(sec) 109 117 123 130 
Tensile Shear 
(kgf/cm.sup.2) 
210.0 215.7 230.7 255.1 
Adhesive 
Strength 
______________________________________ 
EXAMPLE 8 
In the polythiol compounds listed in Table 4 was dissolved at room 
temperature 3 parts by weight of the N-phenyl-N',N'-dimethylaminourea 
obtained in Preparation 3, 100 parts by weight of "EP-828" was added 
thereto, and the components were mixed while defoaming to obtain epoxy 
resin compositions (xxiii)-(xxviii). Compositions (xxiii)-(xxviii) were 
completely uniform liquids. The properties of compositions 
(xxiii)-(xxviii) are shown in Table 4. 
TABLE 4 
__________________________________________________________________________ 
Epoxy Composition xxiii 
xxiv xxv xxvi xxvii 
xxviii 
__________________________________________________________________________ 
EP828 (Parts) 100 100 100 100 100 100 
TMTP (Parts) 70 0 0 0 0 0 
TMTG (Parts) 0 63 0 0 0 0 
PETG (Parts) 0 0 57 0 0 0 
PETP (Parts) 0 0 0 64 51 38 
N-Phenyl-N',N'-dimethylaminourea 
(Parts) 3 3 3 3 3 3 
Gel Time 100.degree. C. 
(min) -- -- 64 46 44 35 
Gel Time 120.degree. C. 
(min) 23 25 19 18 19 17 
Initial Viscosity (poise) 10 13 37 27 36 46 
Shelf Life (week) 3 3 3 4 4 4 
Water Absorption in Boiling Water 1 H 
(%) 0.7 0.8 0.8 0.8 -- -- 
Tensile Shear Adhesive Strength 
(kgf/cm.sup.2) 
-- -- -- -- 226 -- 
T-peel Adhesive Strength 
(kgf/25 mm) 
-- -- -- -- 3.3 -- 
__________________________________________________________________________ 
EXAMPLE 9 
In 51 parts by weight of "PETP" was dissolved at room temperature 3 parts 
by weight of N-phenyl-N',N'-dimethylaminourea, 100 parts by weight of an 
epoxy resin was added thereto, and the components were mixed while 
defoaming to obtain epoxy resin compositions (xxix)-(xxx). Compositions 
(xxix)-(xxx) were completely uniform liquids. The properties of 
compositions (xxix)-(xxx) are shown in Table 5. 
TABLE 5 
______________________________________ 
Epoxy Composition xxix xxx 
______________________________________ 
EP828 (Parts) 0 50 
EP-152 (Parts) 100 0 
EP-154 (Parts) 0 50 
PETP (Parts) 51 51 
N-Phenyl-N',N'-dimethylaminourea 
(Parts) 3 3 
Gel Time 100.degree. C. 
(min) 38 38 
Gel Time 120.degree. C. 
(min) 15 14 
Initial Viscosity (poise) 81 160 
Shelf Life (week) 3 3 
______________________________________ 
EXAMPLE 10 
In 74 parts by weight of "TMTP" was dissolved at room temperature 3 parts 
by weight of a urea compound which was produced by a reaction of phenyl 
isocyanate and diethylamine, 100 parts by weight of "EP-828" was added 
thereto, and the components were mixed while defoaming to obtain epoxy 
resin composition (xxxi). Composition (xxxi) was a completely uniform 
liquid. The gel time of composition (xxxi) at 120.degree. C. was 10 
minutes, and its gel time at 100.degree. C. was 24 minutes. The initial 
viscosity was 13 poise at 25.degree. C. Also, the shelf life was 10 days. 
EXAMPLE 11 
In 74 parts by weight of "TMTP" was dissolved at room temperature 1 part by 
weight of a urea compound which was produced by a reaction of phenyl 
isocyanate and diethylamine, 100 parts by weight of "EP-828" was added 
thereto, and the components were mixed while defoaming to obtain epoxy 
resin composition (xxxii). Composition (xxxii) was a completely uniform 
liquid. The gel time of composition (xxxii) at 120.degree. C. was 15 
minutes, and its gel time at 100.degree. C. was 36 minutes. The initial 
viscosity was 10 poise at 25.degree. C. Also, the shelf life was 2 weeks. 
EXAMPLE 12 
In 74 parts by weight of "TMTP" was dissolved at room temperature 3 parts 
by weight of a urea compound which was produced by a reaction of phenyl 
isocyanate and di-nbutylamine, 100 parts by weight of "EP-828" was added 
thereto, and the components were mixed while defoaming to obtain epoxy 
resin composition (xxxiii). Composition (xxxiii) was a completely uniform 
liquid. The gel time of composition (xxxiii) at 120.degree. C. was 14 
minutes. The initial viscosity was 7 poise at 25.degree. C. Also, the 
shelf life was 3 weeks. 
EXAMPLE 13 
One hundred parts by weight of "EP-828" and 3 parts by weight of 
2,4-bis(N,N-dimethylurea)toluene were kneaded together, 74 parts by weight 
of "TMTP" was added thereto, and the components were stirred and mixed to 
obtain epoxy resin composition (xxxiv). Composition (xxxiv) was a 
completely uniform liquid. The gel time of composition (xxxiv) at 
80.degree. C. was 12 minutes. Also, the working life was 5 days. 
EXAMPLE 14 
One hundred parts by weight of "EP-828" was mixed and kneaded with 3 parts 
by weight of the product of a reaction of 
tris-(3-isocyanato-4-methylphenyl)isocyanurate and 2methylimidazole, 74 
parts by weight of "TMTP" was added thereto, and the components were 
stirred and mixed to obtain epoxy resin composition (xxxv). The gel time 
of composition (xxxv) at 80.degree. C. was 20 minutes. Also, the working 
life was 3 days. 
EXAMPLE 15 
One hundred parts by weight of "EP-828" was kneaded with 3 parts by weight 
of the product of a reaction of 
tris-(3-isocyanato-4-methylphenyl)isocyanurate and 
dimethylaminopropylamine, 74 parts by weight of "TMTP" was added thereto, 
and the components were stirred and mixed to obtain epoxy resin 
composition (xxxvi). The gel time of composition (xxxvi) at 80.degree. C. 
was 12 minutes. Also, the working life was 1 month. 
EXAMPLE 16 
To 100 parts by weight of "EP-828" was added 1 part by weight of "Fujicure 
FXE-1000" and these were mixed at room temperature, after which 74 parts 
by weight of "TMTP" was added thereto, and the components were mixed while 
defoaming to obtain epoxy resin composition (xxxvii). The gel time of 
composition (xxxvii) at 80.degree. C. was 5 minutes, and the gel time at 
60.degree. C. was 18 minutes. The initial viscosity was 3 poise at 
25.degree. C. Also, the working life was 5 days. 
As mentioned above, the polythiol epoxy resin compositions according to the 
present invention have excellent curability at relatively low heating 
temperatures and provide strong adhesive strength, and thus are suitable 
for use in adhesive agents, sealing agents, casting materials and the 
like. By adding an isocyanate group-containing composition to the epoxy 
resin compositions according to the present invention, the adhesive 
strength may be improved without significantly impairing the curability of 
the resin. In addition, the epoxy resin compositions according to the 
present invention have a very long working life, and therefore they are 
extremely useful from the point of view of improving working efficiency. 
Furthermore, since it is possible to preserve the excess composition after 
use, there is no longer any need to discard it, and as a result the 
compositions according to the present invention are extremely useful from 
the standpoint of conservation of resources and environmental protection, 
as well. 
Obviously, numerous modifications and variations of the present invention 
are possible in light of the above teachings. It is therefore to be 
understood that, within the scope of the appended claims, the invention 
may be practiced otherwise than as specifically described herein.