Adhesive compositions for adhering organic synthetic fibers to nitrile group-containing highly saturated copolymer rubbers, method for treating organic synthetic fibers using same, and method for adhering organic synthetic fibers to rubbers using same

An adhesive composition for adhering an organic synthetic fiber to a nitrile group-containing highly saturated copolymer rubber, said composition comprising a nitrile group-containing highly saturated copolymer rubber latex having an iodine value of not more than 120 and a resorcinol-formaldehyde resin, characterized in that the nitrile group-containing highly saturated copolymer rubber latex is obtained by treating a nitrile group-containing unsaturated copolymer rubber latex resulting from emulsion polymerization with hydrogen in the presence of a hydrogenation catalyst to selectively hydrogenate a carbon-carbon double bond of the nitrile group-containing unsaturated copolymer constituting said latex.

This invention relates to an adhesive composition for adhering an organic 
synthetic fiber to a nitrile group-containing highly saturated copolymer 
rubber, a method for treating the organic synthetic fiber using said 
adhesive composition, and a method for adhering the organic synthetic 
fiber to the nitrile group-containing highly saturated copolymer rubber 
using said adhesive composition. 
Composite products of fibers and rubbers have been used in automobile 
timing belts, polyribbed belts, conveyor belts, hoses, diaphragms, etc. On 
this occasion, an oil resistant acrylonitrile-butadiene copolymer rubber 
has been hitherto employed. However, with control of automobile exhaust 
gases, miniatuarization of an engine room for lightweight automobile, 
closing of the engine room for prevention of noise, etc., oil resistance 
and heat resistance have been required of rubbers. Accordingly, nitrile 
group-containing highly saturated copolymer rubbers having heat resistance 
and oil resistance have been lately widely adopted in the above usages. As 
a result, adhesives for well adhering the fibers to the nitrile 
group-containing highly saturated polymer rubbers have been demanded. 
The present inventors proposed an adhesive composition for adhering an 
organic fiber to a nitrile group-containing highly saturated copolymer 
rubber, wherein a nitrile group-containing highly saturated copolymer 
rubber latex is used as one component (EP 285094). Their further 
investigations revealed that when using a latex obtained by phase 
inversion from an organic solvent solution of a nitrile group-containing 
highly saturated copolymer rubber resulting from hydrogenation of an 
alpha,beta-ethylenically unsaturated nitrile-conjugated diene copolymer 
rubber, adhesion (initial adhesion) in producing a belt molded article and 
adhesion (heat-resistant adhesion) after using it at high temperatures are 
at satisfactory levels but adhesion (water-resistant adhesion) after 
dipping it in hot water is not enough. 
Accordingly, it is an object of this invention to provide an adhesive 
composition for adhering an organic fiber to a nitrile group-containing 
highly saturated copolymer rubber and excellent in initial adhesion, 
heat-resistant adhesion and water-resistant adhesion. 
Another object of this invention is to provide a method for treating the 
fiber with said adhesive composition. 
Still another object of this invention is to provide a method for adhering 
the organic synthetic fiber to the nitrile group-containing highly 
saturated copolymer rubber. 
The present inventors have made extensive studies to achieve these objects, 
and consequently found that when using a nitrile group-containing highly 
saturated copolymer rubber latex obtained by hydrogenating a nitrile 
group-containing unsaturated copolymer rubber via a specific method, said 
water-resistant adhesion improves. This finding has led to completion of 
this invention. 
Thus, in accordance with this invention, there are provided an adhesive 
composition for adhering an organic synthetic fiber to a nitrile 
group-containing highly saturated copolymer rubber, said composition 
comprising a nitrile group-containing highly saturated copolymer rubber 
latex having an iodine value of not more than 120 and a 
resorcinol-formaldehyde resin, characterized in that the nitrile 
group-containing highly saturated copolymer rubber latex is obtained by 
treating a nitrile group-containing unsaturated copolymer rubber latex 
resulting from emulsion polymerization with hydrogen in the presence of a 
hydrogenation catalyst to selectively hydrogenate a carbon-carbon double 
bond of the nitrile group-containing unsaturated copolymer constituting 
said latex; a method for treating the organic synthetic fiber 
characterized by using the adhesive composition; and a method for bonding 
the organic synthetic fiber to the nitrile group-containing highly 
saturated copolymer rubber by vulcanization characterized by treating the 
organic synthetic fiber with the adhesive composition. 
The nitrile group-containing unsaturated copolymer rubber latex used in 
this invention is a latex of a copolymer rubber comprising a conjugated 
diene and an alpha,beta-ethylenically unsaturated nitrile and if required, 
an ethylenically unsaturated monomer as a third component, said latex 
being obtained by emulsion-copolymerizing these monomers. 
In the copolymer rubber, the proportions of the individual monomers are 
usually 30 to 90% by weight of the conjugated diene unit, 10 to 50% by 
weight of the alpha,beta-ethylenically unsaturated nitrile unit and 0 to 
20% by weight of the ethylenically unsaturated monomer unit. 
The molecular weight of the copolymer rubber is not limited in particular. 
The alpha,beta-ethylenically unsaturated nitrile may be any nitrile if 
containing a nitrile group and a polymerizable unsaturated bond. Concrete 
examples thereof are acrylonitrile and methacrylonitrile. 
The conjugated diene is not limited in particular either. Concrete examples 
thereof are aliphatic conjugated dienes such as 1,3-butadiene, isoprene, 
2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and halosubstituted butadiene. 
These conjugated dienes may be used either singly or in combination. 
The ethylenically unsaturated monomer used as the third component may be 
any monomer if emulsion-copolymerizable with the conjugated diene and the 
alpha,beta-ethylenically unsaturated nitrile. Concrete examples thereof 
are unsaturated carboxylic acids such as acrylic acid, methacrylic acid, 
itaconic acid and maleic acid and their salts; unsaturated carboxylic acid 
esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl 
(meth)acrylate, 2-ethylhexyl (meth)acrylate, trifluoroethyl 
(meth)acrylate, tetrafluoropropyl (meth)acrylate, ethyl itaconate, butyl 
fumarate, butyl maleate, methoxymethyl (meth)acrylate, ethoxyethyl 
(meth)acrylate, methoxyethoxyethyl (meth)acrylate, cyanomethyl 
(meth)acrylate, 2-cyanoethyl (meth)acrylate, 1-cyanopropyl (meth)acrylate, 
2-ethyl-6-cyanohexyl (meth)acrylate, 3-cyanopropyl (meth)acrylate, 
hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate; 
(meth)acrylamide and its N-substituted derivatives such as N-methylol 
(meth)acrylamide, N,N-dimethylol (meth)acrylamide and N-ethoxymethyl 
(meth)acrylamide; fluoroalkylvinyl ethers such as fluoroethylvinyl ether; 
and vinylpyridine. Moreover, a copolymerizable antioxidant and a 
non-conjugated diene are also included in the ethylenically unsaturated 
monomer of this invention. Concrete examples of the copolymerizable 
antioxidant are N-(4-anilinophenyl)(meth)acrylamide, 
N-(4-anilinophenyl)cinnamamide, N-(4-anilinophenyl)crotonamide, 
N-(4-anilinophenyl)amino-2-hydroxypropyl(meth)allyl ether, 
5-N-(4-anilinophenyl)amino-2-hydroxypentyl (meth)acrylate, 
2-N-(4-anilinophenyl)aminoethyl (meth)acrylate, 
N-[4-(methylanilino)phenyl](meth)acrylamide, N-(4-anilinophenyl)maleimide, 
N-[4-(methylanilino)phenyl]maleimide, 
N-phenyl-4-(3-vinylbenzyloxy)aniline, and 
N-phenyl-4-(4-vinylbenzyloxy)aniline. Concrete examples of the 
non-conjugated diene are vinyl norbornene, dicyclopentadiene, and 
1,4-hexadiene. 
Concrete examples of such nitrile group-containing unsaturated copolymer 
rubber are a butadiene-acrylonitrile copolymer rubber, an 
isoprene-butadiene-acrylonitrile copolymer rubber, an 
isoprene-acrylonitrile copolymer rubber, a butadiene-methyl 
acrylate-acrylonitrile copolymer rubber, a butadiene-acrylic 
acid-acrylonitrile copolymer rubber, and a 
butadiene-ethylene-acrylonitrile copolymer rubber. 
In this invention, a method for emulsion-polymerizing the above monomers 
may be a usual method such as a batchwise method, a semi-batchwise method 
or a continuous method, and a polymerization temperature and a 
polymerization pressure are not particularly limited either. 
The emulsifying agent used in polymerization is not particularly limited 
either and may be an anionic surface active agent, a cationic surface 
active agent, a nonionic surface active agent or an ampholytic surface 
active agent. Of these, the anionic surface active agent is preferable. 
Aliphatic acid series are especially preferable. The amount of the 
emulsifying agent is not limited in particular. From the aspect of 
adhesion of the adhesive composition obtained from this latex, it is 1 to 
10% by weight, preferably 2 to 6% by weight based on the total weight of 
all the monomers. 
A polymerization initiator, a molecular weight modifier and other 
polymerization aids may, if necessary, be those commonly used. 
Moreover, the latex obtained by polymerization may contain an antioxidant 
and a pH adjustor if required. 
The nitrile group-containing highly saturated copolymer rubber latex used 
in this invention is formed by treating a nitrile group-containing 
unsaturated copolymer rubber latex resulting from emulsion polymerization 
with hydrogen in the presence of a hydrogenation catalyst to selectively 
hydrogenate a carbon-carbon double bond of the nitrile group-containing 
unsaturated copolymer constituting the latex. 
The treatment with hydrogen (hydrogenation reaction) of the latex is 
carried out by encapsulating the latex, a hydrogenation catalyst and 
hydrogen in a pressure-resistant vessel, preferably with stirring. The 
sequence of adding them is not limited in particular It is however 
advisable in operation to encapsulate the latex first and hydrogen last. 
The concentration of the latex subjected to the hydrogenation reaction is 
not limited in particular; not more than 20% by weight (as a solids 
content) is preferable. When it exceeds 20% by weight, there is a tendency 
that the average particle size of the latex increases and a coagulum 
occurs. 
In hydrogenation, stability of the latex resulting from emulsion 
polymerization can also be improved by post-adding a surface active agent 
to said latex. At this time, the surface active agent can be the same as 
those taken above as the emulsifying agent for polymerization. It is 
advisable that the amount of the surface active agent is not more than 4% 
based on the weight of the copolymer in order not to decrease the adhesion 
characteristics of the final adhesive composition. 
The hydrogenation catalyst used in this invention is a palladium compound 
that is hard to decompose with water and it is not limited in particular. 
Concrete examples of the palladium compound are various organic compounds, 
inorganic compounds and complex salts, for example, palladium salts of 
carboxylic acids such as formic acid, acetic acid, propionic acid, lauric 
acid, succinic acid, stearic acid, oleic acid, phthalic acid and benzoic 
acid; chlorinated palladium compounds such as palladium chloride, 
dichloro(cyclooctadiene)palladium, dichloro(norbornadiene)palladium, 
dichloro(benzonitrile)palladium, dichlorobis(triphenylphosphine)palladium, 
ammonium tetrachloropalladate (II), and ammonium hexachloropalladate (IV); 
brominated palladium compounds such as palladium bromide; iodized 
palladium compounds such as palladium iodide; and palladium sulfate 
dihydrate; and potassium tetracyanopalladate (II) trihydrate. Of these, 
the palladium salts of carboxylic acids, dichloro(norbornadiene)palladium 
and ammonium hexachloropalladate are most preferable. 
The amount of the hydrogenation catalyst may properly be determined from 
the type of the copolymer being hydrogenated and the intended 
hydrogenation degree It is usually 5 to 6,000 ppm, preferably 10 to 4,000 
ppm based on the weight of the nitrile group-containing unsaturated 
copolymer. It can be more than 6,000 which is however uneconomical. 
A method for adding the hydrogenation catalyst is not limited in 
particular. It may be added in the solid state as such or in the state 
dispersed in water or latex. When the hydrogenation catalyst is dissolved 
in an organic solvent, the organic solvent solution of the hydrogenation 
catalyst is added to the latex of the nitrile group-containing unsaturated 
copolymer which is advisable in efficiency of the hydrogenation reaction 
and operation. 
In this invention, the hydrogenation reaction can be performed with good 
efficiency by adding to the reaction system an organic solvent that can 
dissolve or swell the nitrile group-containing unsaturated copolymer. This 
is presumably because the nitrile group-containing unsaturated copolymer 
constituting the latex is swelled with the organic solvent, making it easy 
for the hydrogenation catalyst to approach the carbon-carbon double bond 
of the copolymer. 
Concrete examples of the organic solvent are aromatic hydrocarbons such as 
benzene, toluene, xylene, and ethylbenzene; halogenated hydrocarbons such 
as dichloroethane, chloroform, chlorobenzene, and carbon tetrachloride; 
ketones such as methyl ethyl ketone, acetone, cyclohexanone, and 
cyclopentanone; carboxylic acid esters such as methyl acetate, ethyl 
acetate, propyl acetate, and butyl acetate; alcohols having 6 or more 
carbon atoms, such as diacetone alcohol and benzyl alcohol; ethers such as 
dioxane, tetrahydrofurane, and ethyl ether; and nitriles such as 
acetonitrile, acrylonitrile and propionitrile. Of these, the ketones and 
the carboxylic acid esters are preferable. They may be used either singly 
or in combination. 
The amount of the organic solvent is at most thrice, preferably at most 1.5 
times, more preferably at most the same as but at least 0.05 time, that of 
the latex by volume ratio. Though the hydrogenation reaction proceeds with 
the organic solvent in an amount exceeding thrice that of the latex, the 
emulsion is liable to be destroyed and separated into a solvent phase and 
an aqueous phase. Accordingly, new steps of separating these two phases 
and recovering the hydrogenated polymer from the solvent phase are needed. 
Within the range of thrice to 1.5 times, the hydrogenation reaction can be 
run while keeping the emulsion state, but the latex particle size 
sometimes increases during the reaction, destroying the emulsion after the 
reaction. 
The organic solvent may be added before, after or simultaneously with, the 
addition of the hydrogenation catalyst. 
The hydrogenation reaction temperature is 0.degree. to 300.degree. C., 
preferably 20.degree. to 150.degree. C. The hydrogenation reaction can be 
carried out at a temperature higher than 300.degree. C. which is however 
liable to cause side reactions other than the intended selective 
hydrogenation reaction of the carbon-carbon double bond, such as 
hydrogenation of the organic solvent, hydrogenation of the nitrile group, 
etc. 
The hydrogen source of the hydrogenation reaction is a gaseous hydrogen or 
dissolved hydrogen. Contact of hydrogen with the carbon-carbon double bond 
of the nitrile group-containing unsaturated copolymer can readily be 
achieved by stirring the reaction system. 
The hydrogen pressure is atmospheric pressure to 300 kg/cm.sup.2, 
preferably 5 to 200 kg/cm.sup.2, more preferably 10 to 80 kg/cm.sup.2. It 
may be a high pressure of more than 300 kg/cm.sup.2 which results 
unpractically in high cost of equipment and cumbersome handling. 
The hydrogenation degree (i.e. the iodine value of the nitrile 
group-containing copolymer) may be controlled by any means and usually by 
varying the hydrogenation pressure and the reaction time depending on the 
intended hydrogenation degree (iodine value). 
After the hydrogenation reaction is over, excess hydrogen is released 
outside the system, and the hydrogenation catalyst is removed. The removal 
of the hydrogenation catalyst is conducted such that an activated carbon 
is added to the reaction system and adsorbes the hydrogenation catalyst 
which is then removed via centrifugation, filtration, etc. An ion exchange 
resin may replace the activated carbon. Sometimes, the nitrile 
group-containing highly saturated copolymer latex obtained by 
hydrogenation can be used in the next step with the hydrogenation catalyst 
present therein (without removal of said catalyst therefrom). 
When using the solvent, said solvent is removed by a known method such as 
steam stripping. 
The thus obtained nitrile group-containing highly saturated copolymer 
rubber latex is concentrated to an intended concentration depending on the 
usage by an ordinary method such as a rotary evaporator, a high-speed 
centrifugal separator, etc. 
The nitrile group-containing highly saturated copolymer rubber latex used 
in this invention is, as stated above, obtained from the nitrile 
group-containing unsaturated copolymer rubber latex, and the iodine value 
of the nitrile group-containing highly saturated copolymer rubber has to 
be not more than 120. When it exceeds 120, heat-resistant adhesion of the 
obtained adhesive composition undesirously decreases. 
The adhesive composition for bonding the organic synthetic fiber to the 
nitrile group-containing highly saturated copolymer rubber vulcanization 
in this invention comprises the above nitrile group-containing highly 
saturated copolymer rubber latex and the resorsinol-formaldehyde resin as 
essential components. 
The resorsinol-formaldehyde resin is not limited in particular and known 
resins (resins shown in e.g. Japanese Laid-open Patent Application No. 
142635/80) are available. Moreover, 
2,6-bis(2,4-dihydroxyphenylmethyl)-4-chlorophenol or its similar 
compounds, isocyanates, blocked isocyanates, ethylene urea, polyepoxide, 
modified polyvinyl chloride resins can be conjointly used which have been 
so far employed to increase adhesion. 
In the adhesive composition of this invention, the amount (dry weight) of 
the resorcinol-formaldehyde resin is usually 10 to 180 parts by weight per 
100 parts by weight (as a solids content) of the nitrile group-containing 
highly saturated copolymer rubber latex. 
By the way, part of the nitrile group-containing highly saturated copolymer 
rubber latex can be replaced with a styrene-butadiene copolymer rubber 
latex, its carboxyl-modified latex, an acrylonitrile-butadiene copolymer 
rubber latex, its carboxyl-modified latex or a natural rubber latex unless 
impairing the scope of this invention. 
The adhesive composition of this invention can be properly used to treat 
organic synthetic fibers. 
The organic synthetic fibers available in this invention are not limited in 
particular. Examples thereof are polyvinyl alcohol fibers, polyester 
fibers, polyamide fibers, and aramide fibers (aromatic polyamide fibers). 
These fibers can take the form of staples, filaments, cord, rope or canvas. 
Other forms are also available. 
A method for treating the fibers with the adhesive composition of this 
invention is not particularly limited. The same method as employed in 
using the known resolcinol-formaldehyde resin-polymer latex adhesive 
composition is available. For example, the fibers are dipped with the 
adhesive composition and if required, dried usually at 100.degree. to 
150.degree. C. for 0.5 to 10 minutes, and then heat-treated. The heating 
conditions are not particularly limited; the time and the temperatures are 
those enough to react and fix the adhesive composition adhered by dipping. 
Heating is carried out usually at about 140.degree. to about 250.degree. 
C. for several minutes. Incidentally, previous to the dipping treatment of 
the fibers, it is also possible to dip the fibers in an isocyanate 
solution, an epoxy solution or a mixed solution thereof and dry them. 
In this invention, the amount adhered (as a solids content) of the adhesive 
composition is not particularly limited. It is usually 2 to 20% by weight, 
preferably 3 to 10% by weight based on the fibers. 
The adhesive composition of this invention is effectively used for bonding 
the organic synthetic fibers to the nitrile group-containing highly 
saturated copolymer rubber by vulcanization, thereby providing a composite 
product of the organic synthetic fibers and the nitrile group-containing 
highly saturated copolymer rubber. 
The nitrile group-containing highly saturated copolymer rubber (hereinafter 
referred to at times as an "adhered rubber") used as a product to which 
the orgnaic synthetic fibers are adhered in this invention may be a 
copolymer rubber of an alpha,beta-ethylenically unsaturated nitrile and a 
conjugated diene and/or an ethylenically unsaturated monomer, or its 
derivatives. The content of the nitrile group-containing monomer unit in 
the adhered rubber is usually 10 to 60% by weight from the aspect of oil 
resistance of the rubber product combined with the fibers. The iodine 
value is not more than 120, preferably not more than 100, more preferably 
not more than 80 from the aspect of heat resistance. The adhered rubber 
can be formed by using the same monomers as employed to form the aforesaid 
nitrile group-containing unsaturated copolymer rubber latex. 
The adhered rubber can be obtained directly as a nitrile group-containing 
highly saturated copolymer rubber by copolymerization of the above 
monomers or by hydrogenating the nitrile group-containing unsaturated 
copolymer rubber. On this occasion, the polymerization method and the 
hydrogenation method are not limited in particular. Concrete examples of 
the adhered rubber are a highly saturated butadiene-acrylonitrile 
copolymer rubber, a highly saturated isoprene-butadiene-acrylonitrile 
copolymer rubber, a highly saturated isoprene-acrylonitrile copolymer 
rubber, a highly saturated butadiene-methyl acrylate-acrylonitrile 
copolymer rubber, a highly saturated butadiene-acrylic acid-acrylonitrile 
copolymer rubber, a highly saturated butadiene-ethylene-acrylonitrile 
copolymer rubber, and a butyl acrylate-ethoxyethyl acrylate-vinyl 
norbornene-acrylonitrile copolymer rubber. 
A method for bonding the organic synthetic fibers treated with the adhesive 
composition of this invention to the nitrile group-containing highly 
saturated copolymer rubber by vulcanization is not limited in particular. 
The same method as hitherto employed to bond the fibers to the rubber by 
vulcanization can be used. That is, it can be achieved by embedding the 
organic acrylonitrile copolymer rubber, a highly saturated 
butadiene-methyl acrylate-acrylonitrile copolymer rubber, a highly 
saturated butadiene-acrylic acid-acrylonitrile copolymer rubber, a highly 
saturated butadiene-ethylene-acrylonitrile copolymer rubber, and a butyl 
acrylate-ethoxyethyl acrylate-vinyl norbornene-acrylonitrile copolymer 
rubber. 
A method for bonding the organic synthetic fibers treated with the adhesive 
composition of this invention to the nitrile group-containing highly 
saturated copolymer rubber by vulcanization is not limited in particular. 
The same method as hitherto employed to bond the fibers to the rubber by 
vulcanization can be used. That is, it can be achieved by embedding the 
organic synthetic fibers in the rubber blend obtained by adding 
compounding agents such as a vulcanizing agent, a filler, etc. to a 
rubber, and then conducting vulcanization. The vulcanization conditions 
are usually a pressure of 5 to 100 kgf/cm.sup.2, a temperature of 
120.degree. to 180.degree. C. and a time of 1 to 120 minutes. 
In accordance with this invention, there can be obtained the adhesive 
composition for adhering the organic synthetic fibers to the nitrile 
group-containing highly saturated copolymer rubber, said composition being 
excellent in initial adhesion, heat-resistant adhesion and water-resistant 
adhesion. Since the composite product of the nitrile group-containing 
highly saturated copolymer rubber and the organic synthetic fibers 
obtained by using the adhesive composition of this invention is superior 
to the product obtained by using the conventional adhesive composition in 
intial adhesion, adhesion after heat ageing (heat-resistant adhesion) and 
water-resistant adhesion, it is useful to produce various belts such as 
automobile timing belts and polyribbed belts and various hoses such as 
pressure hoses and freon hoses, wherein the organic synthetic fibers are 
used as a tension-resistant material. 
The following Examples illustrate this invention-more specifically. Parts 
and percents in said Examples are by weight unless otherwise indicated.

REFERENTIAL EXAMPLE 1 
(Preparation of a latex by emulsion polymerization) 
A 1000-milliliter pressure-resistant bottle was charged with 240 g of 
water, 4 g of potassium oleate, and 37 g of acrylonitrile in this 
sequence. After the inside of the bottle was purged with a nitrogen gas, 
63 g of butadiene was forced therein. The bottle was put in a constant 
temperature bath, and 0.25 g of ammonium persulfate was added as a 
catalyst, followed by polymerization for 16 hours. There resulted a latex 
A-5 of an acrylonitrile-butadiene copolymer rubber (hereinafter 
abbreviated as "NBR") containing 37% by weight of bound acrylonitrile. 
Subsequently, the latex was adjusted to a solids content of 12%, and 400 ml 
of the latex was charged in a 1 liter autoclave fitted with a stirrer. A 
nitrogen gas was passed for 10 minutes to remove oxygen present in the 
latex, and palladium acetate as a hydrogenation catalyst was dissolved in 
240 ml of acetone and added. The inside of the system was replaced twice 
with a hydrogen gas, and pressured with a hydrogen gas until the pressure 
inside the system reached 30 atm. The contents were then heated to 
50.degree. C., and reacted for 6 hours under stirring. After the contents 
were cooled to room temperature, excess hydrogen was purged, and the 
organic solvent was removed via an evaporator. The resulting latex was 
concentrated to a solids content of about 40% to afford a highly saturated 
NBR latex A-1 having an iodine value of 108. 
Highly saturated NBR latexes A-2 and A-3 having different iodine values and 
a NBR latex A-4 having a high degree of unsaturation were obtained in the 
same manner as above except changing the hydrogenation conditions (a 
reaction time and/or an amount of the catalyst). The pH, the average 
particle size and the iodine value of these latexes are shown in Table 1. 
TABLE 1 
______________________________________ 
Latex A-1 A-2 A-3 A-4 A-5 
______________________________________ 
Iodine value 
108 42 21 142 308 
Average particle 
0.11 0.10 0.11 0.10 0.09 
size (.mu.) 
Solids content 
40.2 40.1 40.1 40.0 39.8 
(%) 
pH 10.6 10.7 10.6 10.5 11.0 
______________________________________ 
REFERENTIAL EXAMPLE 2 
(Preparation of a latex by phase inversion). 
A NBR latex containing 37% of bound acrylonitrile, which was obtained by 
emulsion polymerization in the same way as above, was coagulated in a 
usual manner. The obtained NBR was dissolved in methyl isobutyl ketone, 
and the butadiene portion of NBR was hydrogenated in the presence of a 
palladium-carbon catalyst to form hydrogenated NBR having an iodine value 
of 80. Sixty grams of the hydrogenated NBR was dissolved in 540 g of a 
solvent mixture of methyl ethyl ketone/cyclohexane (50/50% by volume). To 
the resulting solution were added 32 g of a 15% potassium oleate aqueous 
solution adjusted to pH of 11.5 by potassium hydroxide and 600 g of water 
under stirring with a homomixer (Model M: a tradename for a machine of 
Tokushu Kika Kogyo K.K.). Subsequently, the mixture was stirred at 12,000 
rpm and emulsified. The solvent was removed from the resulting emulsion by 
steam stripping and then concentrated via an evaporator to obtain a latex 
having a solids content of about 30%. Further, the latex was subjected to 
centrifugation at 10,000 rpm at room temperature for 16 minutes with a 
centrifugal separator (Type H 251: a tradename for a product of Kokusan 
Enshinki K.K.) to obtain a latex B-1 having a solids content of 40%. In 
the same way as above, a latex B-2 having a solids content of about 40% 
was obtained from hydrogenated NBR having an iodine value of 28. 
Properties of the resulting latexes are shown in Table 2. 
TABLE 2 
______________________________________ 
Latex B-1 B-2 
______________________________________ 
Iodine value 80 28 
Average particle 0.65 0.68 
size (.mu.) 
Solids content 40.0 40.1 
(%) 
pH 10.2 10.1 
______________________________________ 
REFERENTIAL EXAMPLE 3 
(Preparation of an adhered rubber blend) 
According to a formulation shown in Table 3, a nitrile group-containing 
highly saturated copolymer rubber and compounding agents were kneaded on a 
roll to prepare a sheet of a rubber compound having a thickness of about 
2.5 mm. 
TABLE 3 
______________________________________ 
Formulation a (parts) 
b (parts) 
______________________________________ 
Zetpol 2020 (*1) 100 -- 
Zetpol 2000 (*2) -- 100 
Zinc oxide No. 1 5 5 
Stearic acid 1 1 
SRF carbon 40 40 
Sulfur 0.5 -- 
Tetramethylthiuram 
1.5 -- 
disulfide 
Mercapto- 0.5 -- 
benzothiazole 
Peroxymon F-40 (*3) 
-- 6 
______________________________________ 
(*1) A tradename for a product of Nippon Zeon Co., Ltd.: iodine value 28, 
content of bound acrylonitrile 36% 
(*2) A tradename for a product of Nippon Zeon Co., Ltd.: iodine value 4, 
content of bound acrylonitrile 36% 
(*3) A tradename for a product of Nippon Oils and Fats Co., Ltd.; 
alpha,alphabis-t-butyl peroxide of m,pdiisopropylbenzene 
EXAMPLE 1 
Adhesive compositions were prepared in accordance with a formulation shown 
in Table 4 using the latexes shown in Tables 1 and 2. 
TABLE 4 
______________________________________ 
parts 
______________________________________ 
(RF solution) 
Resorcinol 11.0 
Aqueous solution 16.2 
of formaldehyde 
(37%) 
Sodium hydroxide 3.0 
(10%) 
Water 235.8 
Total 266.0 
(RFL solution) 
Latex 250.0 
RF solution 266.0 
Aqueous ammonia 22.6 
(14%) 
Water 47.9 
Total 586.5 
______________________________________ 
A nylon cord (nylon 6, structure 1,890 d/2) was dipped with the adhesive 
composition by a single cord dip machine for test, and then heat-treated 
at 200.degree. C. for 2 hours. 
The thus treated cord was embedded in the adhered rubber compound to a 
length of 8 mm. Vulcanization was conducted at a temperature of 
150.degree. C. and a pressure of 50 kgf/cm.sup.2 in case of the rubber 
compound (a) and at a temperature of 160.degree. C. and a presure of 5 
kgf/cm.sup.2 for 30 minutes in case of the rubber compound (b) 
respectively. There resulted composite products of the fibers and rubber. 
The resulting composite products were subjected to a cord pulling test 
according to ASTM D 2138-72 to measure initial adhesion. Likewise, the 
composite products were heated in an air oven at 120.degree. C. for 168 
hours and then subjected to the cord pulling test to measure 
heat-resistant adhesion. Moreover, the composite products were left to 
stand in hot water of 50.degree. C. for 72 hours and then measured for 
water-resistant adhesion. The results are shown in Table 5. 
TABLE 5 
__________________________________________________________________________ 
This invention 
Control This invention 
Run No. 1 2 3 4 5 6 7 8 9 
__________________________________________________________________________ 
Latex No. A-1 
A-2 
A-3 
A-4 
B-1 
B-2 
A-5 
A-2 A-3 
Rubber compound 
a a a a a a a b b 
Adhesion (kg/8 mm) 
Initial Adhesion 
25.0 
24.2 
23.8 
24.5 
20.9 
20.2 
19.8 
21.2 
20.9 
Heat-resistant 
21.3 
22.8 
22.6 
19.1 
19.3 
19.0 
13.1 
19.8 
19.4 
adhesion 
Water-resistant 
23.6 
23.1 
22.8 
18.2 
17.6 
16.9 
23.2 
20.1 
20.0 
adhesion 
__________________________________________________________________________ 
The results in Table 5 reveal that when using the adhesive composition of 
this invention, there is obtained the composite product of the organic 
synthetic fibers and the nitrile group-containing highly saturated 
copolymer rubber, said product being excellent in initial adhesion, 
heat-resistant adhesion and water-resistant adhesion, whereas when using 
the adhesive composition prepared from the latex obtained by phase 
inversion, the resulting composite product is poor in water-resistant 
adhesion. 
EXAMPLE 2 
Adhesive compositions were prepared in accordance with a formulation shown 
in Table 6 using the latexes shown in Tables 1 and 2. 
TABLE 6 
______________________________________ 
(Adhesive composition in a first bath) 
parts 
______________________________________ 
(RF solution) 
Resorcinol 16.6 
Aqueous solution 14.7 
of formaldehyde 
(37%) 
Sodium hydroxide 13.0 
(10%) 
Water 321.7 
Total 366.0 
(RFL solution) 
Latex 250.0 
RF solution 366.0 
Total 616.0 
(Dipping solution) 
RFL solution 616.0 
Vulcabond E (20%) (*1) 
400.0 
Total 1016.0 
______________________________________ 
(*1) A tradename for a product of Valnax International Ltd.: 2,2 
bis(2,4dihydroxy-phenylmethyl)-4-chlorophenol composition 
A polyester cord (structure 1,100 d/2.times.3) was dipped with the adhesive 
composition obtained in accordance with the formulation shown in Table 6 
by a single cord dip machine for test, and heat-treated at 245.degree. C. 
for 1 minute. The resulting cord was dipped with the adhesive composition 
obtained in accordance with the formulation shown in Table 4, and then 
heat-treated at 245.degree. C. for 1 minute. 
From the thus obtained polyester cord, a composite product of fibers and 
rubber was produced as in Example 1 and subjected to a cord pulling test 
as in Example 1. The results are shown in Table 7. 
From the results shown in Table 7, it follows that when using the polyester 
fibers, this invention also provides the composite product of the organic 
synthetic fibers and the nitrile group-containing highly saturated 
copolymer rubber having excellent water-resistant adhesion. 
TABLE 7 
______________________________________ 
This This 
invention 
Control invention Control 
Run No. 10 11 12 13 14 15 16 
______________________________________ 
Latex No. A-2 A-3 B-2 A-5 A-2 A-3 B-2 
Rubber a a a a b b b 
compound 
Adhesion (kg/8 mm) 
Initial Adhesion 
30.7 30.1 28.4 21.4 27.3 26.7 24.1 
Heat-resistant 
25.1 24.8 23.5 16.2 22.7 22.5 21.8 
adhesion 
Water-resistant 
26.9 26.2 20.1 19.7 25.3 24.9 17.8 
adhesion 
______________________________________ 
EXAMPLE 3 
An aramide cord (Kevlar: a tradename for a ,1 product of E. I. du Pont de 
Nemours & Co., structure 1,500 d/2) was heat-treated with a pretreating 
solution shown in Table 8 by a single cord dip machine for test at 
220.degree. C. for 1 minute. 
TABLE 8 
______________________________________ 
parts 
______________________________________ 
Glycerol diglysidyl ether 
2.22 
10% sodium hydroxide 0.28 
5% AEROSOL" OT (solids 
0.56 
content 75%) (*1) 
Water 96.94 
Total 100.00 
______________________________________ 
(*1) A tradename for a product of American Cyananid Co. 
The resulting cord was further dipped with the adhesive composition 
obtained in accordance with the formulation shown in Table 4, and then 
heat-treated at 250.degree. C. for 1 minute. From the thus obtained 
aramide cord, a composite product of fibers and a rubber was prepared as 
in Example 1 and subjected to a cord pulling test as in Example 1. The 
results are shown in Table 9. 
TABLE 9 
__________________________________________________________________________ 
This invention 
Control 
This invention 
Control 
Run No. 17 18 19 20 21 22 23 
__________________________________________________________________________ 
Latex No. A-2 A-3 B-2 
A-5 
A-2 A-3 B-2 
Rubber compound 
a a a a b b b 
Adhesion (kg/8 mm) 
Initial Adhesion 
22.8 
21.9 
18.9 
10.6 
18.6 
18.1 
15.8 
Heat-resistant 
20.9 
20.1 
16.5 
5.8 
17.3 
17.0 
13.9 
adhesion 
Water-resistant 
21.2 
20.8 
15.0 
8.1 
17.8 
17.8 
12.9 
adhesion 
__________________________________________________________________________