Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~l~ 3~9L7~
The present invention relcltes to hydroquinone bis
[~-(o-aminophenylthio)alkyl] ethers and -their use as hardeners
for polyurethane elastomer.
Heretofore, aromatic diamines have been used as
hardeners in the preparation of polyurethane elastomers. Various
aromatic diamine type hardeners have been proposed. The import-
ant characteristics required for the hardeners are as follows:-
Firstly, the ilardeners should be a low meltlng point
solid or liquid from processability, labour hygiene and energy
saving considerations;
Secondly, the pot life, i.e. the time from mixing the
hardener with a mixture of polyisocyanate and polyol or a pre-
polymer having the terminal isocyanate group to the mixture
being non-flowable for casting, should be suitable;
Thirdly, the set time as the time from molding the
mixture to demolding the cast product for processability, espec-
ially efficiency, should be suitable;
~` Fourthly, the hardener should be easily produced and
be stable; and
Fifthly, the resulting polyurethane elastomer should
have excellent physical properties.
However, these requirements are contradictory. For
example, if the short set time is required, the pot life is
shortened to cause trouble in processing. Accordingly, it is
difficult to obtain a hardener having satisfactory and balanced
characteristics. Thus for example, p-bis(o-aminophenylthio-
methyl)benzene has a structure similar to that of the hardeners
of the present invention, however, it has high melting point as
134 to 136~C to provide poor processability.
The present invention provides hardeners for poly-
urethane elastomers which have the above-mentioned balanced
characteristics.
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According to the presen-t invention there are provided
hydroqulnone bis[~ (o-aminophenylthio)alkyl ethers having the
formula
NH2
~ S -(CH2)n- ~ O -(C112)n-S ~ (I)
wherein n is 2 or 3 which are useful as hardeners for polyurethane
elastomers .
The hydroquinone bis[~-(o-aminophenylthio)alkyl ethers
having the formula
NH2
<~ S--(CH2)n-- ~0 (CH2)n S~
where n is 2 or 3 include the following compounds:
hydroquinone bis[2-(o-aminophenylthio)ethyl]ether, and
hydroquinone bis[3-(o-aminophenylthio)propyl]ether.
The hydroquinone bis[~-(o-aminophenylthio)alkyl]ethers
of the present invention may be produced by reacting a hydro-
quinone with a dihalo compound having the formula : -
X-(CH2)n-X (II)
. ,~.
where X represents a halogen atom; and n is 2 or 3 in the .
presence of a dehydrohalogenating base to produce a hydroquinone ~ - :
bis(~-haloalkyl)ether having the formula
X-(CH2)n~ ~ ~ O-(CH2)n-X (III)
- 30 where n and X are defined above and then reacting benzothiazole
with the product in the presence of a dehydrohalogenating base.
~ 3~
The reaction in the first step is usually carried out
in a polar organic solvent such as dimetliylsulfoxide, hexamethyl-
phosphoric triamide, dimethylformamide and dimethylacetamide.
The reaction in the second step is usually carried out in an
aqueous solution.
The dihalo compounds having the formula (II) used in
the process of the present invention include 1,2-dichloroethane,
1,3-dichloropro~ane, 1,2-dibromoethane and 1,3-dibromopropane.
The dehydrohalogenating bases include alkali metal
hydroxides such as sodium hydroxide and potassium hydroxide.
The compounds of the present invention may be used as
hardeners for producing polyurethane elastomers. The polyurethane
elastomer is produced by reacting a polyhydroxy compound with a
diisocyanate and a hardener for a main chain extending reaction
and a crosslinking reaction to harden the product.
In the manufacture of polyurethane elastomer using the
compound of the present invention as hardener, the hardener in a
molten condition is added to a heated reaction mixture of a poly-
isocyanate with a polyol or a polyurethane prepolymer having
terminal isocyanate groups or a polyisocyanate is added to a
mixture of a polyol and the hardener and then, the mixture is
thoroughly mixed and poured into a casting mold and hardened.
Suitable polyisocyanates include hexamethylene diiso-
cyanate (HMDI), cyclohexane diisocyanate, 2,4-tolylene diiso-
cyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), and a
- mixture of 2,4-TDI and 2,6-TDI, dimer and trimer of 2,4-tolylene
diisocyanate, xylylene diisocyanate (XDI), meta-xylylene diiso-
cyanate (MXDI), m-phenylene diisocyanate, 4,4'-biphenyl diiso-
cyanate, diphenyl ether-4,4'-diisocyanate, 3,3'-ditoluene-4,4'-
diisocyanate (TODI), dianisidine diisocyanate (DADI), 4,4'-di-
phenylmethane diisocyanate (MDI), 3,3'-dimethyl-4,4'-diphenyl-
metilane diisocyanate, 1,5-naphthalene diisocyanate, (NDI) and
g7~
triphenylmethane triisocyanate (TTI ~ .
Suitable polyols include polyols having a molecular
weight of 500 to 8,000 and two or more hydroxyl groups such as
aliphatic polyester glycols e.g. polyethylene adipate, poly-
butylene adipate and polypropylene adipate which are obtained
by a condensation polymerization of an aliphatic glycol and a
dicarboxylic acid; polyalkylene ether glycols e.g. polypropylene
ether glycol and tetramethylene ether glycol which are obtained
by a ring-opening polymerization of ethyleneoxide, propylene-
oxide and tetrahydrofuran; a polyester glycol obtained by a ring-
opening polymerization of -caprolactone; a diol obtained by
hydroxylation of terminal groups of polybutadiene; copolymers
of two types of alkyleneoxides; copolymers of two kinds of
glycols and a dicarboxylic acid; polyester polyols obtained by
the co-condensation polymerization of dicarboxylic acid with a
polyol such as an aromatic glycol, a long chain diol, glycerine
or trimethylol propanei and polyetherpolyols obtained by a ring-
.
opening polymerization epoxide and ether compound, such as
ethyleneoxide, propyleneoxide and tetrahydrofuran with a polyol
initiator such as glycerin, trimethylolpropane.
The polyurethane prepolymers having terminal isocyanate
group are produced by reacting said polyol with excess of said
.
polyisocyanate and may be prepolymers having terminal isocyanate
groups based on a polyether or a polyester glycol. Typical pre-
polymers include a prepolymer obtained by reacting polytetra-
methylene glycol with excess of tolylenediisocyanate, a prepoly-
mer obtained by reacting polyethylene adipate with excess of
tolylenediisocyanate and a prepolymer obtained by reacting poly-
caprolactonediol with excess of tolylenediisocyanate.
The hardeners used in the present invention is added
at an amount of about 0.8 to 1.2, preferably 0.80 to 1.0,
equivalents of the total of amino groups of the hardener and
1~.3~7~
hydroxy groups of the polyols depending upon the polyols per
equivalent of isocyanate yroups. A ra-tio of hydroxy groups of
the polyol to amino ~roups of the hardener can be varied in
wide range and is preferably 0.~ to 5 equivalents of hydroxy
groups of the polyol per equivalent of the amino groups.
The hardeners used in the present invention are novel.
The processability can be remarkably improved by using the com-
pound (I) as hardener in comparison with the use of the conven-
tional hardeners.
~oreover, polyurethane elastomers having the balanced
hardeners characteristics and excellent mechanical properties
can be obtained by incorporating the compound (I) as hardener of
the present invention.
The present invention will be further illustrated by
the following Examples
EXAMPLE 1:
Synthesis of Compound (1):
In a 1 Q four necked flask equipped with a thermometer,
a condenser, a dropping funnel and a stirrer, 27.5 g (0.25 mol)
of hydroquinone, 28.1 g (0.5 mol) of potassium hydroxide and
300 mQ of dimethylsulfoxide were charged and stirred and 247.5 g
(2.5 mol) of 1,2-dichloroethane was added dropwise. After the
addition, the mixture was refluxed for 3 hours. After the reac-
tion, benzene was added to extract the oily product and the
benzene phase was washed with water and benzene was distilled
off to obtain 54.1 g of hydroquinone bis(2-chloroethyl)ether
as a brown liquid (yield of 92%).
In a 500 mQ four necked flask equipped with a thermo-
meter, a condenser, and a stirrer, 45 g (0.33 mol) of benzo-
thiazole, 27.3 g (0.68 mol) of sodium hydroxide and 150 mQ of
water were charged.
The mixture was refluxed with stirring for 3 hours to
~L~ 3~ 5
form a solution. Into the solution, 40.4 g (0.172 mol) of
hydroquinone bis(2-chloroethyl)ether was added and the mixture
was refluxed for 3 hours. After the reaction, toluene was
; added to the reaction mixture to extract with toluene. The
toluene phase was washed with water and toluene was distilled
off and the resulting residue was recrystalli~ed from toluene
to obtain 58.1 g bis[2-(o-aminophenylthio)ethyl]ether (yield
of 82% based on hydroquinone bis(2-chloroethyl)ether).
Appearance: yellow crystal
Melting point: 105 to 108.5C
IR spectrum:
-NH2 structure: 3320 cm 1; 3450cm
EXAMPLE 2:
Synthesis of Compound (2): ~ -
In accordance with the process of Example 1 except using
282.5 g (2.5 mol) of 1,3-dichloropropane instead of 1,2-dichloro-
ethane and using 45.3 g (0.172 mol) of hydroquinone bis(3-chloro-
propyl)ether instead of hydroquinone bis(2-chloroethyl)ether, the
reactions were carried out to obtain 59.9 g of hydroquinone bis
- 20 [3-(o-aminophenylthio)propyl]ether (yield of 79.0% based on
hydroquinone bis(3-chloropropyl)ether).
Appearance: brown oily product
IR spectrum:
-NH2 structure: 3320cm 1; 334
EXAMPLE 3:
Production of polyurethane elastomer:
After melting 19.2 g of hydroquinone bis[2-(o-amino-
phenylthio)ethyl]ether obtained in Example 1, it was added to
100 g of a prepolymer having isocyanate groups of 4.34 wt. %
obtained by reacting polytetramethyleneglycol (OH value of 114)
with tolylenediisocyanate (95% of 2,4-TDI and 5% of TDI) (ratio
of -NCO: -NH2 of 1:09) which was heated at 80C.
-- 6
1~ 3~
The reaction mixt~re was stirred for about 60 seconas
so as to be h~rrlocJeneous ana was poured in-to a mold (lOOmm x 250
mm x 2 mm) ileated to 100C. After setting the product, it was
taken out of the mold and it was heated at 100C for 15 hours
as an after curing to obtain a polyurethane elastomer. Various
physical properties of the polyurethane elastomer were measured
by Japanese Industrial Standard K-6301. The rèsul-ts are shown in
Table l.
EX~PLE 4:
In accordance wi-th the process of Example 3 except
using hydroquinone bis[3-(o-aminophenylthio)propyl]ether obtained
in Example 2, as a hardener, a polyurethane elastomer was pro-
duced and tested.
Reference l:
In accordance with the process of Example 3 except
using p-bis(o-aminophenylthiomethyl)benzene as a hardener, a
polyurethane elastomer was produced and tested.
The results are shown in Table l.
Table 1: -
Reference
Potlife (min.) 8 10 6
Set time (min.) 30 45 30
Physical properties:
Hardness (Shore A) 95 85 75
Tensile strength (kg/cm2) 348 243 71
Tear strength (kg/cm) 100 57 39
Rebound elasticity (%) 48 46 38
Modulus 100% (kg/cm2) 91 42 29
Modulus 300% (kg/cm2) 123 98 41
Elongation (%) 520 450 450
Permanent strain (%)38 41 45
EX~PLE 5:
~ _ _
After melting 13. 2 g of hydroquinone bis [2- (o-amino-
phenylthio)ethyl]e-ther, it was added to 100 g of a prepolymer
naving isocyanate groups of 3.0 wt. % obtained by reacting poly-
ethyleneadipate (OH value of 56.5) with tolylenediisocyanate
(80% of 2,4-TDI and 20% of 2,6-TDI) (ratio of -NCO; -Nh of 1:0.9)
which was heated at 80C.
The reaction mixture was stirred for about 60 seconds
so as to be homogeneous and it was poured into a mold and treated
in accordance with the process of Example 3 so as to obtain a
polyurethane elastomer. Various physical properties of the poly-
urethane elastomer were measured. The results are shown in
Table 2.
EXAMPLE 6:
In accordance with the process of Example 5 except using
hydroquinone bis[3-(o-aminophenylthio)propyl]ether as a hardener,
each polyurethane elastomer was produced and properties were
measured. The results are shown in Table 2.
Reference 2:
In accordance with the process of Example 5 except
using p-bis(o-aminophenylthiomethyl) benzene as a hardener, a
polyurethane elastomer was produced and properties were measured.
The results are shown in Table 2.
S
Table 2
______ _
________ __ j 5 _ ¦ 6 2
Pot life (min.) 13 20 10
Set time (min . )120 180 120
____ _
Physical propertics:
.
Hardness (Shore A)86 77 70
Tensile strength (kg/cm2) 400 415 365
Tear strength (kg/cm) 78 61 46
Rebound e]asticity ( %) 41 40 35
Modulus 100% (kg/cm2) 44 36 33
Modulus 300% (kg/cm2) 70 71 63
Elongation ( %) 720 650 730
Permanent strain ( %) 60 54 60
As shown in Tables l and 2, the hardeners of the pre-
sent invention have remarkably lower melting point in comparison
with that of p-bis (o-aminophenylthiomethyl) benzene and have
balanced superior characteristics as hardeners.
, ,