Process for producing cross-linked resin from bis(2-oxazoline) and aromatic hydroxy-carboxylic acid

A process for producing a novel cross-linked resin which comprises: reacting a bis(2-oxazoline) compound with a reactive compound which has at least one active hydrogen in the molecule, the reactive compound being at least one selected from the group consisting of a sulfonamide, an acid imide, an aromatic hydroxy-carboxylic acid and a bisphenol sulfone compound, in a molar ratio of the reactive compound to the bis(2-oxazoline) compound of not more than about 2, at an elevated temperature. About 5 to about 95 mole % of the reactive compound is replaceable by a dicarboxylic acid. The cross-linked resin may be usable for the production of machinery parts such as rolls and gears and embedded moldings of electrical machinery and apparatus parts as well as for electric insulating materials and dental uses. The cross-linked resin may further find applications in, for example, adhesives and various coating compositions.

This invention relates to a process for producing novel cross-linked 
resins. 
It is already known, as disclosed in U.S. Pat. No. 3,476,712, that the 
reaction of a bis(2-oxazoline) compound with a dicarboxylic acid in an 
equimolar amount under heating produces linear polyesteramides. 
##STR1## 
However, no thermosetting resin has hitherto been known which is formed by 
the reaction of a bis(2-oxazoline) compound and a reactive compound which 
has at least one active hydrogen in the molecule such as a sulfonamide, an 
acid imide, an aromatic hydroxy-carboxylic acid or a bisphenol sulfone 
compound. 
The present inventors have made an intensive investigation on the reaction 
of a bis(2-oxazoline) compound with the reactive compound as above, and 
have found that the reaction in a molar ratio of the reactive compound to 
the bis(2-oxazoline) of not more than about 2 at an elevated temperature 
readily provides a novel three-dimensionally cross-linked resin which has 
especially a high heat-resistance and a very small water-absorptivity. 
It is therefore an object of the invention to provide a process for 
producing novel cross-linked resins. 
The process for producing cross-linked resins of the invention comprises: 
reacting a bis(2-oxazoline) compound with a reactive compound which has at 
least one active hydrogen in the molecule, the reactive compound being at 
least one selected from the group consisting of a sulfonamide, an acid 
imide, an aromatic hydroxy-carboxylic acid and a bisphenol sulfone 
compound, in a molar ratio of the reactive compound to the 
bis(2-oxazoline) compound of not more than about 2, at an elevated 
temperature. 
The bis(2-oxazoline) compound used in the present invention has the general 
formula: 
##STR2## 
wherein R represents a C-C covalent bond or a divalent hydrocarbon group, 
preferably an alkylene, a cycloalkylene or an arylene, e.g., phenylene, 
and R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently represent 
hydrogen, an alkyl or an aryl. In the case where R is a C-C covalent bond, 
the bis(2-oxazoline) compound may be 2,2'-bis(2-oxazoline), 
2,2'-bis(4-methyl-2-oxazoline) or 2,2'-bis(5-methyl-2-oxazoline). Examples 
of the bis(2-oxazoline) compound wherein R is a hydrocarbon group are 
1,2-bis(2-oxazolinyl-2)ethane, 1,4-bis(2-oxazolinyl-2)butane, 
1,6-bis(2-oxazolinyl-2)hexane, 1,8-bis(2-oxazolinyl-2)octane, 
1,4-bis(2-oxazolinyl-2)-cyclohexane, 1,2-bis(2-oxazolinyl-2)benzene, 
1,3-bis(2-oxazolinyl-2)benzene, 1,4-bis(2-oxazolinyl-2)benzene, 
1,2-bis(5-methyl-2-oxazolinyl-2)benzene, 
1,3-bis(5-methyl-2-oxazolinyl-2)benzene, 
1,4-bis(5-methyl-2-oxazolinyl-2)-benzene and 
1,4-bis(4,4'-dimethyl-2-oxazolinyl-2)benzene. These may be used as a 
mixture of two or more. 
According to the invention, the bis(2-oxazoline) compound is reacted with 
an organic reactive compound which has at least one active hydrogen in the 
molecule. The reactive compound specifically includes a sulfonamide, an 
acid imide, an aromatic hydroxy-carboxylic acid and a bisphenol sulfone 
compound. 
The sulfonamide usable in the invention includes an aliphatic sulfonamide 
such as methanesulfonamide or ethanesulfonamide, and an aromatic 
sulfonamide such as benzenesulfonamide, o-toluenesulfonamide, 
p-toluenesulfonamide, naphthalene-.alpha.-sulfonamide or 
naphthalene-.beta.-sulfonamide. The sulfonamide further includes a cyclic 
sulfonamide, e.g., saccharin, which is readily obtainable by the oxidative 
cyclization of o-toluenesulfonamide. 
The acid imide usable in the invention includes an open chain acid imide 
such as diacetamide and a cyclic acid amide such as succinimide, 
glutarimide, parabanic acid, hydantoin, dimethylhydantoin, isocyanuric 
acid, phthalimide or maleinimide. The cyclic imide is preferred among 
these acid imides. 
The aromatic hydroxy-carboxylic acid used in the invention includes benzene 
derivatives, for example, salicylic acid, m-hydroxybenzoic acid, 
p-hydroxybenzoic acid, o-cresotic acid, gallic acid, mandelic acid and 
tropic acid, and naphthalene derivatives, for example, 
.alpha.-hydroxynaphthoic acid and .beta.-hydroxynaphthoic acid. 
The bisphenol sulfone compound usable in the invention includes 
4,4'-dihydroxydiphenylsulfone (bisphenol S) and 
3,3'-dihydroxydiphenylsulfone. The bisphenol sulfone compound may carry 
one or more substituents such as alkyls or halogens on either of the 
aromatic nuclei, as in tetrabromobisphenol S. 
These reactive compounds may be used as a mixture of two or more. 
According to the invention, the reactive compound may be in part replaced 
by a dicarboxylic acid. The use of such a dicarboxylic acid as a component 
of the reactive compound improves in particular the mechanical strength, 
especially the flexural, tensile and impact strength of the resultant 
cross-linked resin. 
The dicarboxylic acid usable in the invention has the general formula: 
EQU HOOC-R'-COOH 
wherein R' is a divalent hydrocarbon group and is fusible at the reaction 
temperature, and includes aliphatic dicarboxylic acids such as malonic 
acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic 
acid, azelaic acid, sebacic acid, dodecandioic acid, dimer acid, 
eicosandioic acid or thiodipropionic acid, and aromatic dicarboxylic acids 
such as phthalic acid, isophthalic acid, terephthalic acid, 
naphthalenedicarboxylic acid, diphenylsulfonedicarboxylic acid or 
diphenylmethanedicarboxylic acid. These may also be used as a mixture of 
two or more. It is preferable that from about 5 mole % to 95 mole % of the 
reactive compound is replaced by the dicarboxylic acid. 
According to the invention, the bis(2-oxazoline) compound and the reactive 
compound, either or both of them being hereinafter often referred to as 
reactants, are reacted at an elevated temperature in a molar ratio of the 
reactive compound to the bis(2-oxazoline) compound of not more than about 
2, preferably in the range of about 1 to about 0.2, to provide the 
cross-linked resin. 
Furthermore, according to the invention, the cross-linking or curing 
reaction is preferably carried out in the presence of a catalyst to 
shorten the curing or gellation time and/or to lowers the reaction 
temperature. 
Various inorganic and organic compounds are effective as the catalyst, and 
the first group of catalysts specifically includes a phosphorous acid 
ester, an organic phosphonous acid ester and an inorganic salt. Among 
these a phosphorous acid ester is most preferred particularly because of 
its high catalytic activity and high solubility in the reaction mixture. 
The phosphorous acid ester is preferably a diester and triester such as 
triphenyl phosphite, tris(nonylphenyl)phosphite, triethyl phosphite, 
tri-n-butyl phosphite, tris(2-ethylhexyl)phosphite, tristearyl phosphite, 
diphenylmonodecyl phosphite, tetraphenyl dipropyleneglycol diphosphite, 
tetraphenyltetra(tridecyl)pentaerythritol tetraphosphite, diphenyl 
phosphite, 
4,4'-butylidenebis(3-methyl-6-t-butylphenyl-di-tridecyl)phosphite and 
bisphenol A pentaerythritol phosphite. These may be used as a mixture of 
two or more. Among these phosphites, those which have phenoxy or 
substituted phenoxy groups are particularly preferred. 
Examples of organic phosphonous acid ester includes esters of an aliphatic 
or aromatic phosphonous acid, such as diphenyl phenylphosphonite, 
di(.beta.-chloroethyl).beta.-chloroethylphosphonite or 
tetrakis(2,4-di-t-butylphenyl)-4,4'-diphenylendiphosphonite. 
Various inorganic salts soluble in the reaction mixture are also effective 
as the catalyst. It is preferred that the salt has not water of 
crystallization. Preferred inorganic salts usable as the catalyst are 
composed of a monovalent or tetravalent cation (inclusive of polyatomic 
cations, e.g., vanadyl or zirconyl) such as lithium, potassium, sodium, 
magnesium, calcium, titanium, zirconium, vanadium, chromium, manganese, 
iron, cobalt, nickel, copper, zinc, cadmium, aluminum, tin or cerium, with 
an anion such as a halide, a nitrate, a sulfate or a chlorate. Among these 
salts, cupric chloride, vanadium chloride, vanadyl chloride, cobalt 
nitrate, zinc chloride, manganese chloride and bismuth chloride exhibit 
excellent catalytic activity. 
The second group of catalysts used in the invention includes an oxazoline 
ring-opening polymerization catalyst such as a strong acid, a sulfonic 
acid ester, a sulfuric acid ester or an organic halide which contains at 
least one halomethyl group in the molecule. The oxazoline ring-opening 
polymerization catalyst is already known, as described in, for example, 
Polymer J., Vol. 3, No. 1, pp. 35-39 (1972) and Polymerization Reaction 
Treatize Course 7, Ring-Opening Polymerization II, pp. 165-189, Kagaku 
Dojin (1973). 
More specifically, the strong acid includes an oxoacid such as phosphorous 
acid, sulfuric acid or nitric acid, a hydroacid such as hydrochloric acid 
or hydrogen sulfide, and an organic strong acid such as phenyl phosphorous 
acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 
dodecylbenzenesulfonic acid, naphthalene-.alpha.-sulfonic acid, 
naphthalene-.beta.-sulfonic acid, sulfanilic acid or phenylphosphonic 
acid. 
The sulfonic acid ester includes methyl p-toluenesulfonate and ethyl 
p-toluenesulfonate. The sulfuric acid ester includes dimethylsulfuric acid 
and diethylsulfuric acid. 
Preferred examples of the organic halide as defined above are a 
monohaloalkane and a polyhaloalkane such as methyl iodide, butyl chloride, 
butyl bromide, butyl iodide, lauryl bromide, allyl bromide or ethane 
tetrabromide. Other examples of the organic halide are mono- or 
polyhalomethylbenzenes, e.g., benzyl bromide and 
p,p'-dichloromethylbenzene. The organic halide as the catalyst further 
includes a haloalkane which has a hydroxyl and/or a carboxyl group in the 
molecule, such as .alpha.-bromopropionic acid, 2,3-dibromopropanol or 
.alpha.-bromobutyric acid. 
Among the above catalysts, the phosphorous acid ester and sulfonic acid 
ester are preferred. 
The catalyst is used in amounts of 0.1-5% by weight, preferably 0.3-3% by 
weight based on the weight of a mixture of the bis(2-oxazoline) compound 
and the reactive compound. 
In the reaction of the invention, the bis(2-oxazoline) compound and the 
reactive compound may be first mixed and then heated to melt together, or 
each of them may be first heated to melt and then mixed together, and when 
necessary, followed by further heating. The catalyst may also be added at 
any stage. For instance, the catalyst may be added to either the 
bis(2-oxazolin) compound or the reactive compound, or the catalyst may be 
added to a mixture of the reactants before, during or after heating to 
melt. 
The reaction temperature at which the cross-linking reaction proceeds 
depends on the individual reactants, i.e., the bis(2-oxazoline) compound 
and the reactive compound as well as the catalyst used, and hence it is 
not specifically limited, however, usually it is not lower than about 
100.degree. C., preferably in the range of about 130.degree. C. to 
230.degree. C. The reaction time or gellation time also varies depending 
on the individual reactants as well as the catalyst used, but usually in 
the range of about 10 seconds to 3 hours. 
According to the invention, cross-linked resins including reinforcements 
and/or fillers are also obtainable, for example, by mixing the 
reinforcement and/or filler with a mixture of the bis(2-oxazoline) 
compound, the reactive compound and the catalyst, and then by heating the 
resultant mixture to cause the cross-linking reaction. 
As the reinforcement, fibrous one which is in use in the ordinary plastic 
industry is usable. Specific examples of such reinforcement are inorganic 
fibers such as glass fibers, carbon fibers, quartz fibers, ceramic fibers, 
zirconia fibers, boron fibers, tungsten fibers, molybdenum fibers, steel 
fibers, berylium fibers and asbestos fibers, natural fibers as cotton, 
flax, hemp, jute or sisal hemp, and synthetic fibers having 
heat-resistance at the reaction temperature such as polyamide fibers or 
polyester fibers. In order to improve adhesion to the cross-linked resin, 
the fibrous reinforcement may be treated in advance with, for example, 
chromium compounds, silane, vinyltriethoxysilane or aminosilane. 
The amount of the reinforcement may be selected, for example, upon the 
viscosity of the molten mixture, the reinforcement used, the requirements 
for cured products, etc., however, it is usually in the range of about 
3-95% by weight, prferably about 5-80% by weight based on the mixture of 
the bis(2-oxazoline) compound and the reactive compound. 
Various fillers may also be incorporated into the cross-linked resin. 
Preferred examples of the filler include oxides such as silica, alumina or 
titanium dioxide, hydroxides such as aluminum hydroxide, carbonates such 
as calcium carbonate or magnesium carbonate, silicates such as talc, clay, 
glass beads or bentonite, carbon materials such as carbon black, metal 
powders such as iron powder or aluminum powder. The amount of the filler 
may be selected as in the case of the reinforcement, and it is usually in 
the range of about 3-500% by weight, preferably about 5-200% by weight 
based on the mixture of the reactants. 
The cross-linked resin produced according to the present invention has 
excellent physical properties inclusive of mechanical strength, abrasion 
strength, heat-resistance and electrical properties as well as excellent 
chemical properties, especially an excellent heat-resistance and a very 
small water absorptivity. Furthermorte, according to the invention, 
cross-linked resin provided with a wide range of physical and chemical 
properties are obtainable by selecting the bis(2-oxazoline) compound and 
the reactive compound and the molar ratio therebetween. For example, the 
partial replacement of the reactive compound by the dicarboxylic acid 
provides the cross-linked resin having a particularly improved 
heat-resistance and mechanical properties. 
Furthermore, the present process permits a rapid curing of the two 
reactants, so that the reaction system is suitably applicable to the 
reactive injection molding (RIM). 
Therefore, The cross-linked resin may be usable for the production of 
machinery parts such as rolls and gears and embedded moldings of 
electrical machinery and apparatus parts as well as for electric 
insulating materials and dental uses. The cross-linked resin of the 
invention may further find applications in, for example, adhesives and 
various coating compositions. 
Furthermore, the cross-linked resin which includes therein reinforcements 
and/or fillers provides resin molds with superior mechanical properties, 
especially outstanding toughness, and heat-resistance to conventional 
thermosetting resins. Therefore, cured products according to the invention 
finds applications not only in the application fields for conventional 
fiber-reinforced or filler-containing plastics, such as applications of 
aircraft, craft, railway vehicles, automobiles, civil engineering, 
construction and building, electrical and electronic appliances, 
anti-corrosion equipment, sporting and leisure goods, medical and 
industrial parts, but also in the new applications where conventional 
fiber-reinforced and filler-containing plastics have failed to achieve 
application development. 
The present invention will be more easily understood with reference to the 
following examples, which however are intended to illustrate the invention 
only and are not to be construed as limiting the scope of the invention. 
In the examples, the thermal deflection temperature was measured over a 
load of 18.6 kg applied to a sample resin sheet, and the water absorption 
was measured by the increase in weight of a sample in the form of disc 
after immersing in water at 23.degree. C. for 24 hours.

EXAMPLE 1 
A mixture of 36 g (0.17 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 14 g (0.11 
mole) of dimethylhydantoin and 1 g of triphenyl phosphite were placed in a 
test tube and heated with occasional stirring in an oil bath of 
200.degree. C. After 10 minutes, the temperature of the mixture reached 
190.degree. C. and after 18 minutes the mixture gelled at 217.degree. C. 
accompanying the generation of reaction heat. 
The cured resin was transparent, hard and pale ambercolored. 
EXAMPLE 2 
A mixture of 15.2 g (0.07 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 4.8 g 
(0.035 mole) of p-hydroxybenzoic acid and 0.2 g of a catalyst shown below 
were weighed into a test tube and heated with stirring in an oil bath of 
150.degree. C. 
The gelation times by the second required for the molten mixture to gel 
after the mixture has reached 120.degree. C. were as follows: 
p-Toluenesulfonic acid 160 
Methyl p-toluenesulfonate 120 
Dimethylsulfuric acid 95 
.alpha.-Bromopropionic acid 220 
EXAMPLE 3 
A mixture of 15.3 g (0.07 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 4.7 g 
(0.05 mole) of succinimide and 0.2 g of a catalyst shown below were 
weighed into a test tube and heated with stirring in an oil bath of 
150.degree. C. 
The gelation times by the second required to gel after the mixture has 
reached 120.degree. C. were as follows: 
p-Toluenesulfonic acid 280 
Methyl p-toluenesulfonate 175 
Dimethylsulfuric acid 105 
EXAMPLE 4 
A mixture of 37.5 g (0.17 mole) of 1,3-bis(2-oxazolinyl-2)benzene and 12.5 
g (0.05 mole) of 4,4'-dihydroxydiphenylsulfone were placed in a beaker and 
was heated in an oil bath of 180.degree. C. to melt the mixture. When the 
molten mixture reached 150.degree. C., 0.5 g of a catalyst shown below was 
added to the mixture, and the gelation time by the second was measured. 
The results are shown below. 
p-Toluenesulfonic acid 35 
Dimethylsulfuric acid 25 
.alpha.-Bromopropionic acid 105 
EXAMPLE 5 
A 10 g powdery mixture of 1,3-bis(2-oxazolinyl-2)benzene and an aromatic 
hydroxy-carboxylic acid as shown below with a molar ratio of the 
carboxylic acid to the bis(2-oxazoline) compound of 1:2, and 0.2 g of 
triphenyl phosphite were weighed into a test tube, and then were placed in 
an oil bath of 180.degree. C. 
The gelation times by the second required to gel after the mixture has 
reached 150.degree. C. were as follows: 
Salicylic acid 330 
p-Hydroxybenzoic acid 1020 
.beta.-Hydroxynaphthoic acid 300 
The cured resins were transparent, hard and pale ambercolored. 
EXAMPLE 6 
A mixture of 130 g (0.60 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 44 g 
(0.30 mole) of phthalimide and 3.5 g of triphenyl phosphite was heated to 
185.degree. C. to melt. Then the mixture was poured into a mold which had 
a cavity of 0.3 cm.times.30 cm.times.13 cm and had been in advance heated 
to 215.degree. C., and then was left standing in an oven at 215.degree. C. 
for 1 hour to allow the mixture to form a cross-linked resin. 
After cooling, the cured sheet 3 mm in thickness was taken out of the mold, 
and was subjected to measurements of the properties, which are shown 
below. 
Thermal deflection temperature 183.degree. C. 
Water absorption 0.3% 
Volume resistivity 3.4.times.10.sup.16 .OMEGA.cm 
Dielectric constant (10.sup.6 Hz) 3.36 
Dielectric loss tangent (10.sup.6 Hz) 0.94 
Dielectric breakdown strength 16 KV/mm 
EXAMPLE 7 
A mixture of 65 g (0.30 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 65 g (0.30 
mole) of 1,4-bis(2-oxazolinyl-2)benzene, 29 g (0.20 mole) of phthalimide 
and 2.4 g of triphenyl phosphite was heated to 180.degree. C. to melt. 
Then the mixture was poured into the same mold as used in Example 6 in 
advance heated to 215.degree. C., and then was cured at 215.degree. C. for 
1 hour. 
After cooling, the cured sheet 3 mm in thickness was found to have the 
following properties: 
Thermal deflection temperature 179.degree. C. 
Water absorption 0.34% 
EXAMPLE 8 
A mixture of 130 g (0.60 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 15 g 
(0.10 mole) of phthalimide, 17 g (0.10 mole) of isophthalic acid and 1.6 g 
of triphenyl phosphite was heated to 160.degree. C. to melt. Then the 
mixture was poured into the same mold as used in Example 6 in advance 
heated to 200.degree. C., and then was cured at 200.degree. C. for 30 
minutes. 
After cooling, the cured sheet 3 mm in thickness was found to have the 
following properties: 
Thermal deflection temperature 164.degree. C. 
Water absorption 0.3% 
Flexural strength 10 kgf/mm.sup.2 
Flexural modulas 570 kgf/mm.sup.2 
EXAMPLE 9 
A mixture of 130 g (0.60 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 55 g 
(0.40 mole) of p-hydroxybenzoic acid and 2.5 g of triphenyl phosphite was 
heated to 130.degree. C. to melt. Then the mixture was poured into the 
same mold as used in Example 6 in advance heated to 200.degree. C., and 
then was left standing in an oven at 200.degree. C. for 1 hour to allow 
the mixture to form a cured sheet. 
After cooling, the cured sheet 3 mm in thickness was taken out of the mold, 
and was subjected to measurements of the properties, which are shown 
below. 
Thermal deflection temperature 163.degree. C. 
Water absorption 0.4% 
Flexural strength 12.2 kgf/mm.sup.2 
Flexural modulas 450 kgf/mm.sup.2 
EXAMPLE 10 
A mixture of 135 g (0.625 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 35 g 
(0.25 mole) of p-hydroxybenzoic acid and 5.1 g of triphenyl phosphite was 
heated to 150.degree. C. to melt. Then the mixture was poured into the 
same mold as used in Example 6 in advance heated to 200.degree. C., and 
then was left standing in an oven at 200.degree. C. for 2 hour to allow 
the mixture to form a cross-linked resin. 
After cooling, the cured sheet 3 mm in thickness was taken out of the mold, 
and was subjected to measurements of the properties, which are shown 
below. 
Thermal deflection temperature 226.degree. C. 
Water absorption 0.10% 
Flexural strength 8 kgf/mm.sup.2 
Flexural modulas 530 kgf/mm.sup.2 
EXAMPLE 11 
A mixture of 54 g (0.25 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 54 g (0.25 
mole) of 1,4-bis(2-oxazolinyl-2)benzene, 47 g (0.25 mole) of 
.beta.-hydroxynaphthoic acid and 3.0 g of triphenyl phosphite was heated 
to 160.degree. C. to melt. Then the mixture was poured into the same mold 
as used in Example 6 in advance heated to 210.degree. C., and then was 
left standing in an oven at 210.degree. C. for 30 minutes to allow the 
mixture to form a cured sheet. 
After cooling, the cured sheet 3 mm in thickness was taken out of the mold, 
and was subjected to measurements of the properties, which are shown 
below. 
Thermal deflection temperature 187.degree. C. 
Water absorption 0.22% 
Flexural strength 12.5 kgf/mm.sup.2 
Flexural modulas 590 kgf/mm.sup.2 
Volume resistivity 1.0.times.10.sup.16 .OMEGA.cm 
Dielectric constant (10.sup.6 Hz) 3.5 
Dielectric loss tangent (10.sup.6 Hz) 0.9.times.10.sup.-2 
Dielectric breakdown strength 16 KV/mm 
EXAMPLE 12 
A mixture of 130 g (0.60 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 41 g 
(0.30 mole) of salicylic acid and 1.5 g of triphenyl phosphite was heated 
to 140.degree. C. to melt. Then the mixture was poured into the same mold 
as used in Example 6 in advance heated to 200.degree. C., and then was 
left standing in an oven at 200.degree. C. for 1 hour to allow the mixture 
to form a cross-linked resin. 
After cooling, the cured sheet 3 mm in thickness was found to have the 
following properties: 
Thermal deflection temperature 175.degree. C. 
Water absorption 0.26% 
EXAMPLE 13 
A mixture of 135 g (0.625 mole) of 1,3-bis(2-oxazolinyl-2)benzene and 35 g 
(0.25 mole) of salicylic acid was heated to melt, and 1.7 g of 
p-toluenesulfonic acid was added thereto with an effective stirring to 
provide a uniform mixture. The mixture was then poured into the same mold 
as used in Example 6 in advance heated to 200.degree. C., and then was 
left standing in an oven at 200.degree. C. for 2 hours to allow the 
mixture to form a cross-linked resin. 
After cooling, the cured sheet 3 mm in thickness was found to have the 
following properties: 
Thermal deflection temperature 208.degree. C. 
Water absorption 0.22% 
Flexural strength 11 kgf/mm.sup.2 
Flexural modulas 590 kgf/mm.sup.2 
EXAMPLE 14 
A mixture of 130 g (0.60 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 28 g 
(0.20 mole) of p-hydroxybenzoic acid, 29 g (0.20 mole) of adipic acid and 
3.7 g of triphenyl phosphite was heated to 130.degree. C. to melt. Then 
the mixture was poured into the same mold as used in Example 6 in advance 
heated to 200.degree. C., and then was cured at 200.degree. C. for 30 
minutes. 
After cooling, the cured sheet 3 mm in thickness was found to have the 
following properties: 
Thermal deflection temperature 122.degree. C. 
Water absorption 0.53% 
Flexural strength 21 kgf/mm.sup.2 
Flexural modulas 480 kgf/mm.sup.2 
EXAMPLE 15 
A mixture of 135 g (0.625 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 26 g 
(0.19 mole) of p-hydroxybenzoic acid, 13 g (0.06 mole) of sebacic acid and 
2.6 g of triphenyl phosphite was heated to 140.degree. C. to melt. Then 
the mixture was poured into the same mold as used in Example 6 in advance 
heated to 200.degree. C., and then was cured at 200.degree. C. for 2 
hours. 
The cured sheet was found to have the following properties: 
Thermal deflection temperature 206.degree. C. 
Water absorption 0.4% 
Flexural strength 21 kgf/mm.sup.2 
Flexural modulas 550 kgf/mm.sup.2 
EXAMPLE 16 
A mixture of 113 g (0.53 mole) of 1,3-bis(2-oxazolinyl-2)benzene and 38 g 
(0.15 mole) of 4,4'-dihydroxydiphenyl sulfone was heated to 130.degree. 
C., and then 0.75 g of methyl p-toluenesulfonate was added thereto with an 
efective stirring. Then the resulting mixture was poured into the same 
mold as used in Example 6 in advance heated to 180.degree. C., and then 
was cured at 180.degree. C. for 2 hours. 
The cured sheet was found to have the following properties: 
Thermal deflection temperature 270.degree. C. 
Water absorption 0.3% 
Flexural strength 12 kgf/mm.sup.2 
Flexural modulas 550 kgf/mm.sup.2 
EXAMPLE 17 
A mixture of 97 g (0.45 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 38 g (0.15 
mole) of 4,4'-dihydroxydiphenyl sulfone, 22 g (0.15 mole) of adipic acid 
and 1.6 g of triphenyl phosphite was heated to 130.degree. C. to melt. 
Then the mixture was poured into the same mold as used in Example 6 in 
advance heated to 200.degree. C., and then was left standing in an oven at 
200.degree. C. for 1 hour to allow the mixture to form a cross-linked 
resin. 
After cooling, the cured sheet was found to have the following properties: 
Thermal deflection temperature 138.degree. C. 
Water absorption 0.4% 
Flexural strength 12.3 kgf/mm.sup.2 
Flexural modulas 440 kgf/mm.sup.2 
EXAMPLE 18 
A mixture of 105 g (0.49 mole) of 1,3-bis(2-oxazolinyl-2)benzene and 45 g 
(0.25 mole) of saccharin was heated to 155.degree. C., and then 2.2 g of 
triphenyl phosphite was added thereto with an effective stirring. Then the 
resulting mixture was poured into the same mold as used in Example 6 in 
advance heated to 210.degree. C., and then was cured at 210.degree. C. for 
1 hour. 
The cured sheet was found to have the following properties: 
Thermal deflection temperature 188.degree. C. 
Water absorption 0.1% 
Flexural strength 9 kgf/mm.sup.2 
Flexural modulas 680 kgf/mm.sup.2 
EXAMPLE 19 
A mixture of 34.6 g (0.16 mole) of 1,3-bis(2-oxazolinyl-2)benzene and 27.4 
g (0.16 mole) of p-toluenesulfonamide and 0.43 g of triphenyl phosphite 
was heated to 170.degree. C. and then the resulting mixture was placed in 
a cylindrical mold provided with a heater. When the mixture reached a 
temperature of 110.degree. C., it became transparent and gelled after 23 
minutes. After heating for further 20 minutes, the mixture was left 
standing for cooling. The thus obtained product was taken out of the mold, 
which was found to have a Shore hardness D of 94. 
EXAMPLE 20 
A mixture of 147 g (0.68 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 50 g 
(0.34 mole) of adipic acid, 11.6 g (0.068 mole) of p-toluenesulfonamide 
and 2.1 g of triphenyl phosphite was placed in a stainless steel beaker 
and was heated to melt in an oil bath. 
When the mixture reached a temperature of 115.degree. C., the mixture was 
poured into the same mold as used in Example 6 in advance heated to 
200.degree. C., and then was left standing in an oven at 200.degree. C. 
for 40 minutes to allow the mixture to form a cross-linked resin. 
After cooling, the cured sheet was found to have a thermal deflection 
temperature of 98.degree. C. 
EXAMPLE 21 
A 71 g quantity (0.66 mole) of 1,3-bis(2-oxazolinyl-2)benzene, 9 g (0.13 
mole) of p-hydroxybenzoic acid, 9 g (0.13 mole) of salicylic acid, 11 g 
(0.11 mole) of sebacic acid and 2 g of triphenyl phosphite were mixed 
thoroughly in a mortar, and the mixture was heated to about 130.degree. C. 
to be molten. On a hot plate heated at 120.degree.-130.degree. C. were 
placed a polyester mold-releasing film and then glass plain-woven cloth MG 
253A (Asahi Fiber Glass K.K.) in 14 layers. 
The resin was poured on the layers of glass cloth to impregnate them with 
the resin uniformly while degassing with the use of an aluminum degassing 
roller for lamination. Thereafter the layers of glass cloth were covered 
with a polyester mold-releasing film, followed by allowing to cool to room 
temperature. The resultant resin-impregnated layers of glass cloth were 
substantially tack-free. 
After removing the polyester mold-releasing films, the layers of glass 
cloth were placed between plate molds having on thier surfaces coatings of 
ordinary silicone-based releasing agent, and cured at about a temperature 
of 200.degree. C. under a pressure of 20 kg/cm.sup.2 for 1 hour to provide 
a flat sheet about 3 mm in thickness. 
A test specimen was cut out of the flat sheet and was subjected to 
measurement of physical properties. The tensile strength, flexural 
strength and flexural modulus were measured in accordance with JIS K 6911, 
and the tensile modulus and tensile elongation in accordance with JIS K 
7113, while the compression strength and Izod impact strength in 
accordance with JIS K 7208 and JIS K 7110, respectively. The content of 
resin was determined in accordance with JIS K 6919. The results are as 
follows: 
Resin content 42.8% by weight 
Tensile strength 32.7 kgf/mm.sup.2 
Tensile modulus 2180 kgf/mm.sup.2 
Tensile elongation 1.93% 
Flexural strength 48.1 kgf/mm.sup.2 
Flexural modulas 2170 kgf/mm.sup.2 
Compression strength 56.0 kgf/mm.sup.2 
Izod impact strength 77 kg.cm/cm.sup.2 
EXAMPLE 22 
A flat sheet was formed in the same manner as in Example 21 except the use 
of carbon fiber plain-woven cloth #3101 (Toho Rayon K.K.) in 12 layers in 
place of the glass fiber plain-woven cloth. The flat sheet was subjected 
to measurement of physical properties in the same manner as in Example 21 
except the resin content which was determined by immersing the sheet in 
sulfuric acid to decompose and remove the resin therefrom and by weighing 
the resulting residue. The results are as follows: 
Resin content 41.6% by weight 
Tensile strength 62.8 kgf/mm.sup.2 
Tensile modulus 5840 kgf/mm.sup.2 
Tensile elongation 1.09% 
Flexural strength 96.0 kgf/mm.sup.2 
Flexural modulas 5030 kgf/mm.sup.2 
Compression strength 52.1 kgf/mm.sup.2 
Izod impact strength 65 kg.cm/cm.sup.2