Process for producing rubber-reinforcing aromatic polyamide multifilament yarn

An aromatic polyamide multifilament yarn having a high bonding property to a rubber material and a high resistance to fraying of individual filaments, is produced by impregnating an aromatic polyamide multifilament yarn with a treating liquid comprising a first liquid rubber component (A) comprising at least one rubber compound provided with terminal hydroxyl or epoxy groups and having a molecular weight of 500 to 10,000, a second liquid rubber component (B) comprising at least one rubber compound provided with terminal isocyanate groups and having a molecular weight of 500 to 10,000, and an additive selected from antioxidants, antiaging agents, and epoxy compounds; heat treating the impregnated multifilament yarn at 100.degree. to 260.degree. C. for 30 to 260 seconds; twisting the heat treated multifilament yarn at a twist coefficient K satisfying the relationship (I): EQU 1.ltoreq.K.ltoreq.5 (I) wherein K is defined by the equation (II): EQU K=(T.times.D.sup.1/2)/2874 (II) T=twist number/m and D=denier of the multifilament yarn; PA0 applying an adhesive agent containing a resorcinol-formaldehyde resin and a rubber latex, to the twisted multifilament yarn and curing the adhesive agent on the multifilament yarn.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a rubber-reinforcing aromatic polyamide 
multifilament yarn. More particularly, the present invention relates to a 
rubber-reinforcing aromatic polyamide multifilament yarn having an 
excellent bonding property to rubber materials and a high resistance to 
fraying of individual filaments. 
When a multifilament yarn-reinforced rubber cyclic belt, for example, 
timing belt or low edge V-belt is produced by cutting in round slices a 
cylindrical product in which a reinforcing multifilament yarn material 
(cord) is embedded in a rubber matrix, peripheral faces of the 
mutifilament yarns are exposed on the cut face of the belt, on this cut 
face individual filaments are often frayed from the multifilament yarns. 
The rubber-reinforcing multifilament yarn of the present invention 
exhibits a high resistance to the fraying of the individual filaments. 
2. Description of the Related Art 
It is known that aromatic polyamide filaments or fibers generally have 
excellent mechanical strength, modulus of elasticity, dimensional 
stability and heat resistance and thus are useful as reinforcing fibers 
for tires, belts and hoses that are used under hard conditions. The 
aromatic polyamide filaments, in particular, has a high specific tensile 
strength and specific modulus of elasticity and therefore are useful as 
light weight reinforcing filaments, in place of reinforcing steel wires. 
Generally, when the aromatic polyamide multifilament yarns are used as 
reinforcing filaments for a timing belt or low edge V-belt, the belt is 
produced in such a manner that a cylindrical material in which an aromatic 
polyamide multifilament yarn is embedded in a rubber matrix is formed, and 
the cylindrical material is cut in round slices by using a cutter. On the 
cut faces of the belt, peripheral faces of the multifilament yarns are 
exposed, and a portion of the individual filaments is frayed from the 
multifilament yarns and extend from the cut faces of the belt to the 
outside therefore, thereby causing the quality of the resultant belt to be 
lowered. Namely, if the belt having the frayed individual filaments is 
placed on a pulley and subjected to rotation, the frayed individual 
filaments are abraded by the pulley and divided into fine pieces that are 
sprinkled around the pulley, or the frayed individual filaments reduces 
the durability of the belt. 
The above-mentioned disadvantages can be eliminated by mechanically 
removing or cutting the frayed individual filaments from the belt during 
the belt-producing procedure. This removal operation significantly reduces 
the productivity of the belt. Accordingly, this disadvantage is a 
significant barrier against industrially using the aromatic polyamide 
multifilament yarns as a reinforcing material for rubber material. 
To eliminate the above-mentioned disadvantages, Japanese Unexamined Patent 
Publication Nos. 1-207,480 and 4-29,644 disclose an attempt to prevent the 
fraying of individual filaments from the aromatic polyamide multifilament 
yarns by treating the multifilament yarn with a specific treating agent. 
However, this attempt was not always successful because the treated 
aromatic polyamide multifilament yarns exhibited a reduced mechanical 
strength, lowered bonding properties and/or a poor durability. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a process for producing a 
rubber-reinforcing aromatic polyamide multifilament yarn having excellent 
bonding properties to rubber materials, and a high resistance to fraying 
of individual filaments therefrom even when the peripheral faces of the 
individual filaments embedded in the rubber matrix are exposed to the 
outside, without reducing the resistance of the multifilament yarn to 
fatigue. 
The above-mentioned object can be attained by the process of the present 
invention for producing a rubber-reinforcing aromatic polyamide 
multifilament yarn, comprising the steps of: 
impregnating an aromatic polyamide multifilament yarn with a treating 
liquid comprising: 
(A) a first liquid rubber component comprising at least one rubber compound 
provided with two terminal groups consisting of a member selected from the 
groups consisting of hydroxyl and epoxy groups per molecule thereof and 
having a molecular weight of from 500 to 10,000 and 
(B) a second liquid rubber component comprising at least one rubber 
compound provided with two terminal isocyanate groups per molecule thereof 
and having a molecular weight of 500 to 10,000; 
heat-treating the impregnated multifilament yarn at a temperature of from 
100.degree. C. to 260.degree. C. for 30 to 260 seconds; 
twisting the heat-treated multifilament yarn at a twist coefficient 
satisfying the relationship (I): 
EQU 1.ltoreq.K.ltoreq.5 (I) 
wherein K represents a twist coefficient of the multifilament yarn, defined 
by the equation (II): 
EQU K=(T.times.D.sup.1/2)/2874 (II) 
in which T represents a twist number per m of the mutifilament yarn, 
applied thereto, and D presents a denier of the multifilament yarn; and 
applying an adhesive agent containing a resorcinol-formaldehyde resin and a 
rubber latex, to the twisted multifilament yarn. 
In the process of the present invention, the hydroxyl-terminated rubber 
compound of the first liquid rubber component (A) may be further provided 
with at least one epoxy group located in the inside portion of the 
molecule thereof. 
Also, in the process of the present invention, the treating liquid for the 
impregnating step optionally further comprises an antioxidant comprising 
at least one member selected from the groups consisting of antioxidant 
hindered phenolic compounds, antioxidant amine compounds, antioxidant 
phosphorus compounds and antioxidant sulfur compounds. 
Further, in the process of the present invention, the treating liquid for 
the impregnating step optionally further comprises a rubber antiaging 
agent comprising at least one member selected from the group consisting of 
antiaging aldehyde-amine reaction products, antiaging ketone-amine 
reaction products, antiaging amine compounds and antiaging phenol 
compounds. 
Further, in the process of the present invention, the twisting step is 
preferably carried out in such a manner that the heat treated 
multifilament yarn is primary-twisted at a primary twist coefficient 
satisfying the relationship (III): 
EQU 0.2.ltoreq.K.ltoreq.1 (III) 
wherein K is as defined above, then a plurality of the primary-twisted 
multifilament yarns are paralleled to each other, and the resultant 
paralleled multifilament yarn is final-twisted at a final twist 
coefficient satisfying the relationship (I): 
EQU 1.ltoreq.K.ltoreq.5 (I) 
wherein K is as defined above. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The aromatic polyamide multifilament yarn usable for the present invention 
preferably comprises an aromatic polyamide having aromatic recurring units 
in an amount of 80 to 100 molar %, more preferably 85 to 100 molar %, 
based on the total molar amount of all the recurring units. 
The aromatic recurring units include those of the formulae: 
##STR1## 
wherein R.sup.1 and R.sup.2 respectively and independently from each other 
represent a member selected from the group consisting of a hydrogen atom 
and alkyl groups having 1 to 5 carbon atoms, for example, methyl, ethyl, 
propyl, butyl and pentyl groups, preferably the hydrogen atom, and Ar 
represents a divalent aromatic group. 
The divalent aromatic group is preferably selected from the groups of the 
formulae: 
##STR2## 
wherein Ar.sup.1 represents a divalent aromatic cyclic group, for example, 
a phenylene groups or naphthylene group, X represents a member selected 
from --O--, --S-- and --NH-- bonds, preferably --O-- and --NH-- bonds, Y 
represents a member selected from --O--, --S--, --SO.sub.2 --, --CH.sub.2 
--,--C(CH.sub.3).sub.2 --, --CO--, --NH-- and NR.sup.3 -- bonds in which 
R.sup.3 represents an alkyl group having 1 to 5 carbon atoms, preferably 
--O--, --S-- and --CO-- bonds, more preferably an --O-- bond. 
Also, the divalent aromatic cyclic group represented by Ar is preferably 
selected from the group consisting of 1,4-phenylene, 1,3-phenylene, 
4,4'-biphenylene, 1,5-naphthylene, 2,6-naphthylene and 2,5-pyridilene 
groups, more preferably is a 1,4-phenylene group. 
The divalent aromatic group represented by Ar may be unsubstituted or 
substituted by one or more substituents selected from, for example, 
halogen atoms, for example, chlorine, bromine and fluorine atoms, lower 
alkyl groups, for example, methyl, ethyl, isopropyl, n-propyl groups, 
lower alkoxyl groups, for example, methoxyl and ethoxyl groups, a cyano 
group, an acetyl group and a nitro group. 
The aromatic polyamide multifilament yarn usable for the present invention 
comprises at least one member selected from poly-p-aminobenzamide, 
poly-p-phenylene terephthalamide, 
poly-p-aminobenzhydrazideterephthalamide, poly-terephthalic acid 
hydrazide, and poly-m-phenylene-isophthalamide. Those aromatic polyamides 
may be used alone or as a mixture of two or more thereof. 
The aromatic polyamide multifilament yarn preferably has a total denier of 
200 to 9,000, more preferably 400 to 6,000, and is composed of 50 to 6,000 
individual filaments having a denier of 0.5 to 10, more preferably 0.75 to 
6.0. 
In the process of the present invention, the treating liquid for the 
impregnating step comprises a first liquid rubber component (A) and a 
second liquid rubber component (B). 
Generally, liquid rubber compounds having reactive and functional groups 
located at the two terminals of the molecule thereof are referred to as 
RFL liquid rubber compounds. 
The first liquid rubber component (A) comprises at least one rubber 
compound provided with two hydroxyl groups or two epoxy groups located at 
the two terminals of the molecule thereof, and having a molecular weight 
of 500 to 10,000. 
The hydroxyl-terminated rubber compound for the first liquid rubber 
component (A) is preferably selected from the group consisting of 1,2 
type-polybutadiene glycol, 1,4-type polybutadiene glycol, 1,2 and 
1,4-mixed type polybutadiene glycol, polyisoprene glycol, polychloroprene 
glycol, poly-1,3-pentadiene glycol and polycyclopentadiene glycol, each 
having a molecular weight of 500 to 10,000. 
The hydroxyl-terminated rubber compound can be prepared by, for example, a 
radical polymerization of diene monomers in the presence of an initiator, 
for example, hydrogen peroxide, peracetic acid or an azo compound 
containing a hydroxyl group. 
The epoxy-terminated rubber compound for the first liquid rubber component 
(A) is preferably selected from the group consisting of 
terminal-epoxidized 1,2-type polybutadiene, 1,4-type polybutadiene, 1,2 
and 1,4-mixed type polybutadiene, polyisoprene, polychloroprene, 
poly-1,3-pentadiene and polycyclopentadiene compounds, each having a 
molecular weight of 500 to 10,000. 
The epoxy-terminated rubber compound can be prepared by, for example, an 
epoxidation reaction of an ethylenically unsaturated hydrocarbon group 
(--CH.dbd.CH--) of a rubber compound with hydrogen peroxide and p-toluene 
sulfonic acid. 
The hydroxyl-terminated rubber compound usable for the first liquid rubber 
component (A) may be provided with at least one epoxy group located in the 
inside portion of the molecule thereof, in addition to the two terminal 
hydroxyl groups. 
The hydroxyl-terminated, epoxy-consisting rubber compound can be produced 
by oxidizing the hydroxyl-terminated rubber compound with a peroxide 
compound, for example, peracetic acid or hydrogen peroxide. In this 
oxidizing reaction, ethylenically unsaturated hydrocarbon groups 
(--CH.dbd.CH--) in the hydroxyl-terminated rubber compound, for example, 
poly-1,2-butadiene glycol, are completely or partially converted to 
epoxide groups 
##STR3## 
The hydroxyl-terminated, epoxy-containing rubber compound usable for the 
first liquid rubber component (A) is preferably selected from the group 
consisting of epoxidized poly-1,2-butadiene glycol, poly-1,4-butadiene 
glycol, polyisoprene glycol, polychloroprene glycol, poly-1,3-pentadiene 
glycol, and polycylopentadiene glycol compounds. 
If the molecular weight of the hydroxyl or epoxy-terminated rubber compound 
for the first liquid rubber component (A) is less than 500, the resultant 
rubber component (A) exhibits an unsatisfactory bonding (adhesion) 
strength to the rubber materials. 
Also, the molecular weight of more than 10,000 results in an undesirably 
raised viscosity of the resultant first liquid rubber component (A). 
The second liquid rubber component (B) comprises at least one rubber 
compound provided with two isocyanate groups located at two terminals of 
the molecule thereof and having a molecular weight of 500 of 10,000. 
The isocyanate-terminated rubber compound is preferably selected from the 
group consisting of 1,2-type polybutadiene diisocyanate, 1,4-type 
polybutadiene diisocyanate, 1,2 and 1,4- mixed type polybutadiene 
diisocyanate, polyisoprene diisocyanate, polychloroprene diisocyanate, 
poly-1,3-pentadiene diisocyanate and polycyclopentadiene diisocyanate. 
The isocyanate-terminated rubber compound can be prepared by, for example, 
reacting a carboxyl-terminated rubber compound with an acryl azide 
compound. 
In the treating liquid for the impregnating step, the first liquid rubber 
component (A), and the second liquid rubber component (B) are preferably 
present in a weight ratio ((A)/(B)) of 1:9 to 9:1, more preferably 2:8 to 
8:2, still more preferably 3:7 to 7:3. 
When the weight ratio ((A)/(B)) is more than 9:1, the resultant impregnated 
multifilament yarn exhibits an undesired poor bonding property to the 
rubber matrix and an unsatisfactory resistance to fraying of the 
individual filaments, whereas the resultant treating liquid exhibits an 
increased viscosity and the resultant impregnated multifilament yarn has a 
satisfactory mechanical strength. 
When the weight ratio ((A)/(B)) is less than 1:9, the resultant impregnated 
multifilament yarn exhibits an undesirably high stiffness and thus in the 
twisting step, the utilization efficiency of the mechanical strength of 
the multifilament yarn becomes low, and therefore, the resultant twisted 
multifilament yarn exhibits an unsatisfactorily low mechanical strength. 
In the impregnating step of the process of the present invention, the 
treating liquid is impregnated preferably in an amount of 1 to 25%, more 
preferably 5 to 20%, by dry solid weight based on the weight of the 
multifilament yarn, therein. 
If the amount of the treating liquid impregnated in the multifilament yarn 
is less than 1% by dry solid weight, the resultant impregnated 
multifilament yarn exhibits an unsatisfactorily low resistance to fraying 
of the individual filaments and therefore when used as a reinforcing yarn 
for a power-transmission belt, the individual filaments, which are exposed 
at the edge portion of the belt to the outside, are easily frayed. 
If the amount of the treating liquid is more than 25% by dry solid weight, 
the twisting step cannot effectively utilize the mechanical strength of 
the individual filaments, and thus the resultant twisted multifilament 
yarn possess unsatisfactory mechanical strength. 
In the process of the present invention, the multifilament yarn to be 
subjected to the impregnating step with the treating liquid is preferably 
in a substantially non-twisted state. 
The non-twisted multifilament yarn allows the treating liquid to uniformly 
penetrate and distribute therein. If a twisting step is applied to the 
multifilament yarn prior to the impregnating step, it becomes difficult 
for the treating liquid to uniformly penetrate in and evenly distribute 
throughout the multifilament yarn, and thus the individual filaments in 
the resultant multifilament yarn are not evenly bundled. Accordingly, the 
impregnating step with the treating liquid is preferably applied to the 
substantially non-twisted multifilament yarn. 
The treating liquid for the impregnating step optionally further comprises 
an additional epoxy component (C), in addition to the first and second 
liquid rubber component (A) and (B). The additional epoxy component (C) 
comprises at least one epoxy compound containing at least two epoxy groups 
per molecule thereof and having an epoxy gram equivalent of 0.2 per 100 g 
of the epoxy compound. 
The epoxy compound usable for the additional epoxy component (C) is 
preferably selected from the group consisting of a reaction product of 
polyhydric aliphatic alcohol compounds, for example, ethylene glycol, 
glycerol, sorbitol, pentaerythritol and polyethyleneglycol, with 
halogen-containing epoxide compounds, for example, epichlorohydrin; 
reaction products of polyhydric phenol compounds, for example, resorcinol, 
bis(4-hydroxyphenyl)dimethylmethane, phenolformaldehyde resins and 
resorcine-formaldehyde resins, with halogen-containing epoxide compounds, 
for example, epichlorohydrin; and polyepoxidization reaction products of 
unsaturated organic compounds with a peroxide compounds, for example 
peracetic acid and hydrogen peroxide, for example, 
4-epoxycyclohexene-epoxide, 
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexenecarboxylate, 
bis(3,4-epoxy-6-methyl-cyclohexylmethyl)adipate. 
A preferable epoxy compound for the additional epoxy component (C) is a 
reaction product of polyhydric aliphatic alcohol compounds with 
epichlorohydrin, for example, polyhydric aliphatic 
alcohol--polyglycidylether compounds. These epoxy compounds effectively 
impart excellent characteristics to the products produced by the process 
of the present invention. 
Preferably, the additional epoxy component (C) is present in an amount of 
0.01 to 1.0 part, more preferably 0.02 to 0.9 part by dry solid weight per 
part of the total dry solid weight ((A) +(B)) of the first and second 
liquid rubber components (A) and (B). 
The treating liquid for the impregnating step optionally further contains a 
curing agent for the rubber components (A) and (B). The curing agent 
consists, for example, of dibutyl tin dilaurate. 
The treating liquid for the impregnating step optionally further comprises 
an organic solvent, for example, consisting of at least one member 
selected from the groups consisting of toluene, tetrahydrofurane, dioxane, 
methylethylketone and ethyl acetate. 
The first and second liquid rubber components (A) and (B), and optionally, 
the additional epoxy component (C) are dissolved in the organic solvent. 
The components (A) and (B), and optionally, the component (C) may be 
emulsified or dispersed in a liquid medium, for example, water, with the 
aid of a surfactant (emulsifying or dispersing agent), to provide the 
treating liquid. 
In the process of the present invention, the impregnated aromatic polyamide 
multifilament yarn is heat treated at a temperature of from 100.degree. C. 
to 260.degree. C., preferably 150.degree. C. to 250.degree. C., for 30 to 
260 seconds, preferably, 60 to 180 seconds. 
When the heat-treating temperature is lower than 100.degree. C. and/or the 
heat-treating time is shorter than 30 seconds, the curing reaction of the 
compounds impregnated in the multifilament yarn is not satisfactorily 
completed and thus the bundling effect for the individual filaments in the 
yarn is not sufficient. Also the resultant heat treated multifilament yarn 
exhibits an unsatisfactory bonding property to the rubber matrix and 
insufficient resistance to fraying of the individual filaments. 
If the heat treating temperature is higher than 260.degree. C. and/or the 
heat treating time is longer than 260 seconds, the compounds impregnated 
in the multifilament yarn are excessively cured and thus the heat-treated 
multifilament yarn possess an excessive degree of stiffness. This feature 
results in unsatisfactory mechanical strength of the product of the 
present invention. Namely, the resultant rubber-reinforcing multifilament 
yarn is not suitable as a reinforcing yarn for a power-transmission belt. 
In the process of the present invention, the heat-treated aromatic 
polyamide multifilament yarn is twisted at a twist coefficient satisfying 
the relationship (I): 
EQU 1.ltoreq.K.ltoreq.5 (I) 
wherein K represents a twist coefficient of the multifilament yarn defined 
by the equation (II): 
EQU K=(T.times.D.sup.1/2)/2874 (II) 
in which T represents d twist number per m of the multifilament yarn, 
applied thereto, and D is a total denier of the multifilament yarn. 
If the value of K is less than 1, the resultant rubber-reinforcing 
multifilament yarn exhibits an unsatisfactory resistance to fraying of the 
individual filaments when the yarn is used as a rubber-reinforcing 
material for a power-transmission belt. 
If the value of K is more than 5, the twisting step results in a 
significant reduction in mechanical strength and in an undesirable 
increase in elongation of the resultant rubber-reinforcing multifilament 
yarn, and thus the resultant yarn is not suitable as a rubber-reinforcing 
material for a power-transmission belt. 
In a preferable embodiment of the twisting step, the heat treated 
multifilament yarn that is substantially free from a twist is primarily 
twisted in a twisting direction and then finally twisted in the opposite 
direction to the primary twisting direction. The final twisting may be 
omitted. 
In another embodiment of the twisting step, the heat-treated multifilament 
yarn is primarily twisted at a primary twist coefficient of from 0.2 to 1, 
namely 0.2.ltoreq.K.ltoreq.1 wherein K is as defined above; then a 
plurality of the primarily twisted multifilament yarns are paralleled to 
each other, and the resultant paralleled multifilament yarn is finally 
twisted at a final twist coefficient of from 1 to 5, namely 
1.ltoreq.K.ltoreq.5 wherein K is as defined above. 
In this embodiment, the primary twisting operation effectively causes the 
individual filaments in the multifilament yarn to be uniformly paralleled 
and thus the resultant primarily twisted multifilament yarn exhibits 
enhanced mechanical strength, because when an external force is repeatedly 
applied to the multifilament yarn, the applied external force is evenly 
absorbed by the uniformly paralleled individual filaments and thus the 
multifilament yarn exhibits enhanced fatigue resistance and endurance. 
Also, the primary twisting operation effectively causes the individual 
filaments to firmly adhere to each other and thus the resultant twisted 
multifilament yarn exhibits enhanced resistance to fraying of the 
individual filaments. 
In the process of the present invention, an adhesive agent is applied to 
the twisted aromatic polyamide multifilament yarn. The adhesive agent 
comprises a resorcinol-formaldehyde resin and a rubber latex. 
The resorcinol-formaldehyde resin for the adhesive resin is a condensation 
product of resorcinol and formaldehyde preferably in a molar ratio of from 
1:0.1 to 1:8, more preferably from 1:0.5 to 1:5, still more preferably 
from 1:1 to 1:4. 
The rubber latex for the adhesive agent preferably comprises at least one 
member selected from the group consisting of natural rubber latex, 
styrene-butadiene copolymer rubber latex, vinyl pyridine-styrene-butadiene 
terpolymer rubber latex, acrylonitrile copolymer rubber latex, 
hydrogenated acrylonitrile copolymer latex, chlorosulfonated polyethylene 
rubber latex and polychloroprene rubber latex. The above-mentioned rubber 
latexes can be used alone or in a mixture of two or more thereof. 
The type of the rubber latex is selected in consideration of the type of 
the rubber matrix in which the rubber-reinforcing multifilament yarn is 
embedded. 
In the adhesive agent usable for the present invention, the 
resorcinol-formaldehyde resin and the rubber latex are preferably present 
in a dry solid weight ratio of from 1:100 to 25:100, more preferably from 
5:100 to 20:100. 
In an embodiment of the adhesive agent-applying step, the adhesive agent 
further comprises an additional reactant consisting of at least one member 
selected from the group consisting of the formula: 
##STR4## 
wherein R.sup.3 represents a member selected from the group consisting of 
monovalent or divalent aromatic and aliphatic hydrocarbon groups, and n 
represents an integer of 1 or 2, and blocked isocyanate compounds. 
The ethyleneurea compounds are disclosed in Japanese Examined Patent 
Publication No. 57-53912. 
The additional reactant is preferably present in an amount of from 0.5 to 
30% by weight based on the total dry solid weight of the 
resorcinol-formaldehyde resin and the rubber latex. 
The adhesive agent is applied preferably in an amount of from 1% to 10% by 
dry solid weight based on the weight of the twisted filament yarn. 
Preferably, the adhesive agent applied to the twisted multifilament yarn is 
dried at a temperature of from 100.degree. C. to 150.degree. C. for 30 to 
260 seconds and then cured at a temperature of 150.degree. C. to 
260.degree. C. for 30 to 260 seconds. 
In an embodiment of the process of the present invention, the treating 
liquid for the impregnating step further comprises an antioxidant (D) 
comprising at least one member selected from the group consisting of 
antioxidant hindered phenolic compounds, antioxidant amine compounds, 
antioxidant phosphorus compounds and antioxidant sulfur compounds. 
The typical antioxidant hindered phenolic compounds are 
triethyleneglycol-bis[3-(3-t-butyl-6-methyl-4hydroxyphenyl)propionate], 
1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 
2,4-bis(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5triazine, 
pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl4-hydroxyphenyl)propionate], 
2,2-thio-diethylene-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 
octadecyl-3-[3,5-di-tert-butyl-4-hyroxyphenyl)propionate, 
N,N'-hexa-methylene-bis(3,5-di-tert-butyl-4-hydroxycinnamamide, 
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene. 
The antioxidant hindered phenol compounds include sulfur-containing 
hindered phenol compounds, for example, 
2,2-thiobis(4-methyl-6-tert-butylphenol), and 
3,5-di-tert-butyl-4-hydroxybenzylphosphonate diethylester. 
The typical antioxidant amine compounds are 
N,N'-di-sec-butyl-p-phenylene-diamine and alkylated diphenylamines. 
The antioxidant phosphorus compounds include trisnonylphenylphosphite, 
triphenyl-phosphite, and tris (2,4-di-tert-butyl-phenyl)phosphite. 
The antioxidant sulfur compounds include dibutyl-3,3'-thiodipropionate, 
dimystyl-3,3'-thiodipropionate, distearly-3,3'-thiodipropionate, 
pentaerythrityl-tetrakis(3-laurylthiopropionate) and 
ditridecyl-3,3-thiodipropionate. 
The antioxidant (D) is preferably present in an amount of from 0.005 to 
0.05 part, more preferably from 0.01 to 0.03 part, by weight per part by 
the total weight of the first and second liquid rubber components (A) and 
(B). 
The antioxidant (D) is effectively prevent an undesirable oxidation and a 
cross-linking reaction of the double bonds contained in the rubber 
compounds in the treating liquid during the heat-treating step. This 
anti-oxidation action effectively prevents an undesirable reduction in the 
number of double bonds present in the rubber compound molecules applied to 
the multifilament yarn, and an undesirable increase in the stiffness of 
the impregnated multifilament yarn. 
Due to the above-mentioned effects, an undesirable reduction in the 
mechanical strength of the multifilament yarn by the twisting step, and in 
fatigue resistance of the multifilament yarn is prevented. 
Also, the addition of the antioxidant (D) to the treating liquid 
effectively increases interaction between the rubber components (A) and 
(B) with the adhesive agent, and enhances the bonding property of the 
resultant rubber-reinforcing multifilament yarn to the rubber matrix. 
In another embodiment of the process of the present invention, the treating 
liquid for the impregnating step further comprises a rubber antiaging 
agent (E) comprising at least one member selected from the group 
consisting of antiaging aldehyde-amine reaction products antiaging 
ketone-amine reaction products, antiaging amine compounds and antiaging 
phenol compounds. 
The typical antiaging aldehyde-amine reaction products are condensation 
reaction products of acetaldole with 1-naphthylamine. 
The ketone-amine reaction products include polymerization products of 
2,2,4-trimethyl-1,2dihydroquinoline. 
The antiaging amine compounds include N,N'-dinaphthyl-p-phenylenediamine. 
The antiaging phenol compounds include styrene-modified phenol compounds, 
2,6-di-tert-dibutylmethylphenol, 
2,2'-methylene-bis(4-methyl-6-tertbutylphenol) and 
4,4'-thiobis(3-methyl-6-tertbutylphenol). 
The rubber antiaging agent (E) is preferably present in an amount of from 
0.005 to 0.05 part, more preferably from 0.01 to 0.03 part, by weight per 
part of the total dry solid weight of the first and second liquid rubber 
components (A) and (B). 
The rubber antiaging agent effectively prevents the undesirable 
deterioration of the double bonds present in the rubber compounds in the 
treating liquid during the heat-treating step. 
And because of this effect, undesirable crosslinking reactions between the 
reaction products of the rubber compounds are prevented, and thus an 
undesirable increase in stiffness of the impregnated, heat-treated 
multifilament yarn is inhibited. 
The antiaging agent effectively prevents an undesirable reduction in the 
number of double bonds of the reaction products of the rubber components. 
Owing to this effect, the undesirable reductions in the mechanical 
strength, the bonding properties to the rubber matrix and the fatigue 
resistance of the twisted multifilament yarn, are prevented. 
The treating liquid for the impregnating step optionally further comprises 
nickel dibutylthiocarbamate which is a well known antiaging agent for 
rubber compounds. 
The rubber-reinforcing aromatic polyamide multifilament yarn produced by 
the process of the present invention posses excellent bonding properties 
to the rubber matrix and has a high resistance to fraying of the 
individual filaments. Namely, when the rubber-reinforcing multifilament 
yarn is embedded in a rubber matrix, the resultant power-transmission belt 
is quite free from undesirable fraying of individual filaments from the 
multifilament yarns exposing at the cut edge portions of the belt to the 
outside. 
The first liquid rubber component (A) containing the hydroxyl- or 
epoxy-terminated rubber compound and the second liquid rubber component 
(B) comprising the isocyanate-terminated rubber compound are reacted with 
each other to form polyurethane film layers having a high adhesive power 
on the peripheral surfaces of the individual filaments. The individual 
filaments firmly adhere to each other through the polyurethane film 
layers, and this exhibits high anti-fraying properties. The adhesion of 
the individual filaments to each other can be improved by reactions of the 
adhesive agent containing the resorcinol-formaldehyde resin and the rubber 
latex with the urethane bonds or terminal groups in the polyurethane 
molecules in the film layers, or by crosslinking reactions between double 
bonds contained in the polyurethane molecules and the adhesive agent. 
Also, the adhesion can be improved by enhancing the wetting property of 
the polyurethane film layers with the adhesive agent.

EXAMPLES 
The present invention will be further explained in the following specific 
examples, which are intended to be representative rather than restrictive 
of the scope of the present invention. 
In the examples, the fraying resistance, cord bonding strength against 
peeling, T-bonding strength and tensile strength retention upon fatiguing 
were determined by the following test methods. 
(1) Fraying resistance 
A plurality of aromatic polyamide multifilament cord specimens are placed 
in parallel to each other between two rubber sheets having a thickness of 
about 2 mm, and the resultant test piece was vulcanized at a temperature 
of 150.degree. C. under a press-pressure of 50 kg/cm.sup.2 for 30 minutes 
to provide a multifilament cord-reinforced rubber sheet. 
The resultant reinforced rubber sheet was cut along the longitudinal 
direction of the reinforcing cords so as to obtain a specimen having 
portions of the reinforcing cords exposed at the cut edge. 
The appearance of the cut edge of the specimen was visually observed to 
determine the degree of fraying of the individual filaments at the cut 
edge. 
The cut edge face of the specimen was abraded with an emery paper (#AA-150) 
and the appearance of the abraded edge face of the specimen was visually 
observed and the degree of fraying of the individual filaments was 
determined. 
The test results are indicated as follows. 
4: Substantially no fraying of the individual filaments was found. 
3: A few filaments were frayed. 
2: A small satisfactory number of filaments were frayed. 
1: A number of individual filaments were frayed. 
(2) Cord bonding strength against peeling 
This cord strength refers to the bonding strength of a reinforcing cord to 
a rubber matrix against peeling thereof. 
Seven reinforcing cords were embedded parallel to each other in a surface 
portion of a rubber sheet, and the resultant sheet was vulcanized at a 
temperature of 150.degree. C. under a press pressure of 50 kg/cm.sup.2 for 
30 minutes. 
The five cords not including the remaining two cords located at the 
outsidemost positions were peeled from the rubber sheet at a peeling rate 
of 200 mm/min. The bonding strength of the cords to the rubber sheet was 
represented by the force in kg/5 cords necessary to peel the cords from 
the rubber sheet. 
(3) T-bonding strength 
This T-bonding strength refers to a bonding strength of a cord to a rubber 
matrix against a shearing force. 
A reinforcing cord was embedded in a rubber block, and the resultant 
reinforced rubber block was vulcanized at a temperature of 150.degree. C. 
under a press presure of 50 kg/cm.sup.2 for 30 minutes. 
The cord was drawn out from the rubber block at a drawing out rate of 200 
mm/min. 
The bonding strength of the cord to the rubber block was represented by the 
force in kg/cm necessitated to draw out the cord from the rubber block. 
(4) Tensile strength retention upon fatiguing 
This tensile strength retention refers to fatigue resistance. 
A belt type fatigue tester was employed. 
A tensile strength TS.sub.0 of a reinforcing cord was measured. 
The reinforcing cord was put between two rubber sheets having a thickness 
of 2 mm. The resultant specimen was vulcanized at a temperature of 
150.degree. C. under a press presure of 50 kg/cm.sup.2 for 30 minutes. The 
vulcanized specimen was cut into a belt-shaped test piece having a width 
of 50 mm and a length of 500 mm. 
The test piece was fixed to a roller having a diameter of 20 mm of the 
fatigue tester, under a load of 25 kg. The test piece was reciprocated 
500,000 times at a temperature of 120.degree. C. by rotating the roller at 
a rotation number of 120 rpm. 
Then, the cord was taken out from the test piece, and the tensile strength 
TS of the tested cord was measured. 
The tensile strength retention was calculated in accordance with the 
equation: 
##EQU1## 
EXAMPLES 1 TO 9 AND COMATIVE EXAMPLES 1 TO 3 
In each of Examples 1 to 9, an aromatic polyamide multifilament yarn which 
had a yarn count of 1,500 deniers/1,000 filaments and was available under 
the trademark of Tecknola T-200, from Teijin Ltd., was employed. 
A treating liquid was prepared by mixing a first liquid rubber component 
(A) consisting of a liquid 1,2-type polybutadiene glycol having a 
molecular weight of 3,000, and available under the trademark of 
Polybutadiene glycol G-3000, from Nihon Soda Kogyo K.K., with a solution 
of a second liquid rubber component (B) consisting of a liquid 1,2-type 
polybutadiene diisocyunate having a molecular weight of 3,000 in a 
concentration of 50% by weight in methylethylketone; which solution was 
available under the trademark of Polybutadiene Diisocyanate TP 1001, from 
Nihon Soda Kogyo K.K., in a mixing weight ratio (A)/(B) as shown in Table 
1, by admixing, to the mixture, glycerol diglycidylether, available under 
the trademark of EX 313, from Nagase Kasei K.K., in an amount of 5% based 
on the total weight of the components (A) and (B), and dissolving the 
resultant admixture in a concentration of 20% by weight in toluene. 
The aromatic polyamide multifilament yarn was immersed in the treating 
liquid and squeezed at a pick up of about 10% based on the weight of the 
multifilament yarn. 
The resultant impregnated multifilament yarn was dried at a temperature of 
150.degree. C. for 2 minutes and heat-treated at a temperature of 
250.degree. C. for one minute to cure the rubber components (A) and (B). 
The heat-treated multifilament yarn was doubled, and the doubled yarn was 
twisted at a twist coefficient K of 1.0. 
Separately, an adhesive agent was prepared by mixing one part by weight of 
a resorcinol-formaldehyde resin having a molar ratio of resorcinol to 
formaldehyde of 1:6, and 5 parts by weight of a vinyl 
pyridine-styrene-butadiene terpolymer rubber latex (dry solid content: 5% 
by weight). 
The adhesive agent was applied to the twisted double yarn so that the 
adhesive agent was attached in a dry solid amount of 5% based on the 
weight of the twisted yarn, dried at a temperature of 130.degree. C. for 2 
minutes and cured at a temperature of 240.degree. C. for 2 minutes. 
The resultant rubber reinforcing yarn was subjected to the above-mentioned 
tests. 
In each of Comparative Examples 1 to 3, the same procedures as in Example 1 
were carried out except that (i) in Comparative Example 1, the 
impregnating step with the treating liquid was omitted, (ii) in 
Comparative Example 2, the second liquid rubber component (B) was omitted 
from the treating liquid, and (iii) in Comparative Example 3, the first 
liquid rubber component (A) was omitted from the treating liquid. 
The test results are shown in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Performance of resultant rubber-reinforcing yarn 
Bonding 
strength Tensile strength 
against 
T-bonding 
retention upon 
Example Weight ratio 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
(A)/(B) 
resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
1 90/10 2 4.7 13.7 56 
2 80/20 3 5.4 15.5 51 
3 70/30 4 9.6 18.9 55 
4 60/40 4 10.6 17.8 57 
5 50/50 4 10.0 17.2 59 
6 40/60 4 10.3 17.3 57 
7 30/70 4 10.6 17.6 55 
8 20/80 3 8.7 16.5 58 
9 10/90 2 5.3 13.2 60 
Comparative 
1 None 1 2.2 9.6 55 
Example 
2 100/0 1 3.5 10.6 59 
3 0/100 1 4.5 12.9 58 
__________________________________________________________________________ 
Table 1 shows that the rubber reinforcing multifilament yarns of Examples 1 
to 9 exhibited a satisfactory fraying resistance of individual filaments, 
a high bonding strength against peeling, a high T-bonding strength and a 
satisfactory tensile strength retention in the fatigue test. 
EXAMPLES 10 TO 15 AND COMATIVE EXAMPLES 4 AND 5 
In each of Examples 10 to 15 and Comparative Examples 4 and 5, a 
rubber-reinforcing aromatic polyamide multifilament yarn was produced by 
the same procedures as in Example 3, except that the heat-treating step 
was carried out at the temperature and for the time as shown in Table 2. 
The test results are shown in Table 2. 
TABLE 2 
__________________________________________________________________________ 
Heat treating Bonding 
step strength Tensile strength 
Temper- against 
T-bonding 
retention upon 
Example ature 
Time 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
(.degree.C.) 
(sec.) 
resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
3 150 120 4 9.6 18.9 55 
10 100 100 2 6.0 15.8 70 
11 150 150 3 7.4 17.4 67 
12 150 180 3 8.0 19.3 65 
13 150 200 3 8.2 19.5 60 
14 150 220 4 9.0 19.0 58 
15 150 260 4 9.9 18.4 50 
Comparative 
4 90 90 1 4.0 12.8 70 
Example 
5 150 270 4 9.5 19.0 43 
__________________________________________________________________________ 
Table 2 shows that the heat-treating temperature must be in the range of 
from 100.degree. C. to 260.degree. C. and the heat-treating time must be 
from 100 to 260 seconds. 
EXAMPLES 16 TO 24 AND COMATIVE EXAMPLES 6 TO 8 
In each of Examples 16 to 24, an aromatic polyamide multifilament yarn 
having a yarn count of 1,500 deniers/1,000 filaments, and available under 
the trademark of Technola T-200, from Teijin Ltd., was used. 
A treating liquid was prepared by mixing a first liquid rubber component 
(A) consisting of a liquid 1,4-type polybutadiene glycol having an epoxy 
gram equivalent of 200 and a molecular weight of 3,000, and available 
under the trademark of R-45 EPI, from Nagase Kasei Kogyo K.K., with a 
solution of 50% by weight of a second liquid rubber component (B) 
consisting of a liquid 1,2-type polybutadiene diisocyanate having a 
molecular weight of 3,000, in a solvent consisting of methylethylketone, 
which solution was available under the trademark of TP1001, from Nihon 
Soda Kogyo K.K., in a mixing weight ratio (A)/(B) as shown in Table 3, and 
dissolving the mixture in a concentration of 20% by weight in toluene. 
The aromatic polyamide multifilament yarn was immersed in the treating 
liquid and squeezed at a pick up of about 10% based on the weight of the 
multifilament yarn. 
The resultant impregnated multifilament yarn was dried at a temperature of 
150.degree. C. for 2 minutes and heat-treated at a temperature of 
250.degree. C. for one minute to cure the rubber components (A) and (B). 
The heat treated multifilament yarn was doubled, and the doubled yarn was 
twisted at a twist coefficient K of 1.0. 
Separately, an adhesive agent was prepared by mixing one part by weight of 
a resorcinol-formaldehyde resin having a molar ratio of resorcinol to 
formaldehyde of 1:6, with 5 parts by weight of a vinyl 
pyridine-styrene-butadiene terpolymer rubber latex (dry solid content: 5% 
by weight). 
The adhesive agent was applied to the twisted yarn so that the adhesive 
agent was attached in a dry solid amount of 5% based on the weight of the 
twisted yarn, dried at a temperature of 130.degree. C. for 2 minutes and 
cured at a temperature of 240.degree. C. for 2 minutes. 
The resultant rubber-reinforcing multifilament yarn was subjected to the 
above-mentioned tests. 
In each of Comparative Examples 6 to 8, the same procedures as in Example 
16 were carried out except that (i) in Comparative Example 6, the 
impregnating step with the treating liquid was omitted, (ii) in 
Comparative Example 7, the second liquid rubber component (B) was omitted 
from the treating liquid, and (iii) in Comparative Example 8, the first 
liquid rubber component (A) was omitted from the treating liquid. 
The test results are shown in Table 3. 
TABLE 3 
__________________________________________________________________________ 
Performance of resultant rubber-reinforcing yarn 
Bonding 
strength Tensile strength 
against 
T-bonding 
retention upon 
Example Weight ratio 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
(A)/(B) 
resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
16 90/10 2 4.8 14.5 57 
17 80/20 3 5.8 17.1 58 
18 70/30 4 10.3 19.2 53 
19 60/40 4 11.6 18.9 56 
20 50/50 4 11.3 18.6 57 
21 40/60 4 11.2 18.7 56 
22 30/70 4 10.2 18.8 54 
23 20/80 3 8.9 17.5 55 
24 10/90 2 6.3 14.3 57 
Comparative 
6 None 1 2.2 9.6 55 
Example 
7 100/0 1 3.9 11.6 55 
8 0/100 1 4.1 11.9 52 
__________________________________________________________________________ 
Table 3 shows that the rubber reinforcing multifilament yarns of Examples 
16 to 24 exhibited a sastifactory fraying resistance of individual 
filaments, a high bonding strength against peeling, a high T-bonding 
strength and a satisfactory tensile strength retention in the fatigue 
test. 
EXAMPLES 25 TO 30 AND COMATIVE EXAMPLES 9 AND 10 
In each of Examples 25 to 30 and Comparative Examples 9 and 10, a 
rubber-reinforcing aromatic polyamide multifilament yarn was produced by 
the same procedure as in Example 18, except that the heat-treating step 
was carried out at the temperature and for the time as shown in Table 4. 
The test results are shown in Table 4. 
TABLE 4 
__________________________________________________________________________ 
Tensile 
Heat treating Bonding strength 
step strength retention 
Temper- against 
T-bonding 
upon 
Example ature 
Time 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
(.degree.C.) 
(sec.) 
resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
18 150 120 4 10.3 19.2 53 
25 100 100 2 7.0 16.0 65 
26 150 150 3 8.4 18.4 64 
27 150 180 3 9.0 19.5 63 
28 150 200 3 9.5 19.8 61 
29 150 220 4 10.0 19.9 59 
30 150 260 4 9.8 18.4 48 
Comparative 
9 90 90 1 3.5 11.5 72 
Example 
10 150 270 4 9.0 17.5 40 
__________________________________________________________________________ 
Table 4 shows that the heat-treating temperature must be in the range of 
from 100.degree. C. to 150.degree. C. and the heat-treating time must be 
from 100 to 260 seconds. 
EXAMPLES 31 TO 39 AND COMATIVE EXAMPLES 11 TO 13 
In each of Examples 31 to 39, an aromatic polyamide multifilament yarn 
having a yarn count of 1,500 deniers/1,000 filaments, and available under 
the trademark of Technola T-200, from Teijin Ltd., was used. 
A treating liquid was prepared by mixing a first liquid rubber component 
(A) consisting of a liquid 1,4-type polybutadiene diepoxide having a 
molecular weight of 3,000, and available under the trademark of R-45 EPT, 
from Nagase Kasei Kogyo K.K., with a solution of 50% by weight of a second 
liquid rubber component (B) consisting of a liquid 1,2-type polybutadiene 
diisocyanate having a molecular weight of 3,000, in a solvent consisting 
of methylethylketone; which solution was available under the trademark of 
TP1001, from Nihon Soda Kogyo K.K., in a mixing weight ratio (A)/(B) as 
shown in Table 5, and dissolving the mixture in a concentration of 20% by 
weight in toluene. 
The aromatic polyamide multifilament yarn was immersed in the treating 
liquid and squeezed at a pick up of about 10% based on the weight of the 
multifilament yarn. 
The resultant impregnated multifilament yarn was dried at a temperature of 
150.degree. C. for 2 minutes and heat-treated at a temperature of 
250.degree. C. for one minute to cure the rubber components (A) and (B). 
The heat treated multifilament yarn was doubled, and the doubled yarn was 
twisted at a twist coefficient K of 1.0. 
Separately, an adhesive agent was prepared by mixing one part by weight of 
a resorcinol-formaldehyde resin having a molar ratio of resorcinol to 
formaldehyde of 1:6, with 5 parts by weight of a vinyl 
pyridine-styrene-butadiene terpolymer rubber latex (dry solid content: 5% 
by weight). 
The adhesive agent was applied to the twisted yarn so that the adhesive 
agent was attached in a dry solid amount of 5% based on the weight of the 
twisted yarn, dried at a temperature of 130.degree. C. for 2 minutes and 
cured at a temperature of 240.degree. C. for 2 minutes. 
The resultant rubber-reinforcing multi-filament yarn was subjected to the 
above-mentioned tests. 
In each of Comparative Examples 11 to 13, the same procedures as in Example 
33 were carried out except that (i) in Comparative Example 11, the 
impregnating step with the treating liquid was omitted, (ii) in 
Comparative Example 12, the second liquid rubber component (B) was omitted 
from the treating liquid, and (iii) in Comparative Example 13, the first 
liquid rubber component (A) was omitted from the treating liquid. 
The test results are shown in Table 5. 
TABLE 5 
__________________________________________________________________________ 
Performance of resultant rubber-reinforcing yarn 
Bonding 
strength Tensile strength 
against 
T-bonding 
retention upon 
Example Weight ratio 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
(A)/(B) 
resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
31 90/10 2 7.5 13.7 51 
32 80/20 3 8.8 15.5 53 
33 70/30 4 11.6 21.5 54 
34 60/40 4 11.2 20.3 57 
35 50/50 4 10.8 19.3 69 
36 40/60 4 10.7 18.7 67 
37 30/70 4 10.6 18.4 64 
38 20/80 3 8.6 16.5 55 
39 10/90 2 8.6 16.5 55 
Comparative 
11 None 1 2.2 9.6 55 
Example 
12 100/0 1 7.5 12.6 64 
13 0/100 1 4.5 12.9 58 
__________________________________________________________________________ 
Table 5 shows that the rubber reinforcing multifilament yarns of Examples 
31 to 39 exhibited a satisfactory fraying resistance of individual 
filaments, a high bonding strength against peeling, a high T-bonding 
strength and a satisfactory tensile strength retention in the fatigue 
test. 
EXAMPLES 40 TO 45 AND COMATIVE EXAMPLES 14 AND 15 
In each of Examples 40 to 45 and Comparative Examples 14 and 15, a 
rubber-reinforcing aromatic polyamide multifilament yarn was produced by 
the same procedures as in Example 33, except that the heat-treating step 
was carried out at the temperature and for the time as shown in Table 6. 
The test results are shown in Table 6. 
TABLE 6 
__________________________________________________________________________ 
Tensile 
Heat treating Bonding strength 
step strength retention 
Temper- against 
T-bonding 
upon 
Example ature 
Time 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
(.degree.C.) 
(sec.) 
resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
33 150 120 4 11.6 21.5 54 
40 100 100 2 8.2 19.2 62 
41 150 150 3 9.1 19.6 61 
42 150 180 3 9.2 20.1 59 
43 150 200 4 9.6 20.4 55 
44 150 220 4 10.3 20.6 52 
45 150 260 4 10.6 20.2 49 
Comparative 
14 90 90 1 4.0 12.8 70 
Example 
15 150 270 4 9.5 19.0 43 
__________________________________________________________________________ 
Table 6 shows that the heat-treating temperature must be in the range of 
from 100.degree. C. to 150.degree. C. and the heat-treating time must be 
from 100 to 260 seconds. 
EXAMPLES 46 TO 49 AND COMATIVE EXAMPLES 16 TO 18 
In each of Examples 46 to 49, an aromatic polyamide multifilament yarn 
having a yarn count of 1,500 deniers/1,000 filaments, and available under 
the trademark of Technola T-200, from Teijin Ltd., was used. 
A treating liquid was prepared in the following manner. A first liquid 
rubber component (A) consisting of a liquid 1,2-type polybutadiene glycol 
having a molecular weight of 3,000, and available under the trademark of 
G-3000, from Nihon Soda Kogyo K.K., was mixed with a solution of 50% by 
weight of a second liquid rubber component (B) consisting of a liquid 
1,2-type polybutadiene diisocyanate having a molecular weight of 3,000, in 
a solvent consisting of methylethylketone, which solution was available 
under the trademark of TP1001, from Nihon Soda Kogyo K.K., in a mixing 
weight ratio (A)/(B) as shown in Table 7, and the mixture was dissolved in 
toluene. 
The resultant solution was mixed with an antioxidant (D) consisting of 
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzylbenzene, which 
was available under the trademark of Irganox 1330, from Ciba Geigy, in an 
amount of 1% based on the total dry solid weight of the first and second 
liquid rubber components (A) and (B), and then with an additional epoxy 
component (C) consisting of glyceroldiglycidylether, which was available 
under the trademark of EX 313, from Nagase Kasei Kogyo K.K., in an amount 
of 5% based on the total dry solid weight of the first and second 
components (A) and (B), to provide the treating liquid having a 
concentration of 20% by dry solid weight. 
The aromatic polyamide multifilament yarn was immersed in the treating 
liquid and squeezed at a pick up of about 10% based on the weight of the 
multifilament yarn. 
The resultant impregnated multifilament yarn was dried at a temperature of 
150.degree. C. for 2 minutes and heat-treated at a temperature of 
250.degree. C. for one minute to cure the rubber components (A) and (B) 
and the glycerolglycidylether. 
The heat treated multifilament yarn was doubled, and the doubled yarn was 
twisted at a twist coefficient K of 1.0. 
Separately, an adhesive agent was prepared by mixing one part by weight of 
a resorcinol-formaldehyde resin having a molar ratio of resorcinol to 
formaldehyde of 1:6, with 5 parts by weight of a vinyl 
pyridine-styrene-butadiene terpolymer rubber latex (dry solid content: 5% 
by weight). 
The adhesive agent was applied to the twisted yarn so that the adhesive 
agent was attached in a dry solid amount of 5% based on the weight of the 
twisted yarn, dried at a temperature of 130.degree. C. for 2 minutes and 
cured at a temperature of 240.degree. C. for 2 minutes. 
The resultant rubber-reinforcing multifilament yarn was subjected to the 
above-mentioned tests. 
In each of Comparative Examples 16 to 18, the same procedures as in Example 
46 were carried out except that (i) in Comparative Example 16, the 
impregnating step with the treating liquid was omitted, (ii) in 
Comparative Example 17, the second liquid rubber component (B), the 
antioxidant (D) and the additional epoxy component (C) were omitted from 
the treating liquid, and (iii) in Comparative Example 18, the first liquid 
rubber component (A), the additional epoxy component (C) and the 
antioxidant were omitted from the treating liquid. 
The test results are shown in Table 7. 
TABLE 7 
__________________________________________________________________________ 
Performance of resultant rubber-reinforcing yarn 
Bonding 
strength Tensile strength 
against 
T-bonding 
retention upon 
Example Weight ratio 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
(A)/(B) 
resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
46 90/10 2 5.1 13.9 59 
47 60/40 4 10.7 18.7 63 
48 40/60 4 10.4 18.6 65 
49 10/90 3 6.1 14.2 62 
Comparative 
16 None 1 10.3 17.3 59 
Example 
17 100/0 1 10.6 17.6 61 
18 0/100 2 5.3 13.2 62 
__________________________________________________________________________ 
Table 7 shows that the rubber reinforcing multifilament yarn of Examples 46 
to 49 exhibited a satisfactory fraying resistance of individual filaments, 
a high bonding strength against peeling, a high T-bonding strength and a 
satisfactory tensile strength retention in the fatigue test. 
EXAMPLES 50 TO 54 
In each of Examples 50 to 54, a rubber-reinforcing aromatic polyamide 
multifilament yarn was produced by the same procedures as in Example 47 
(weight ratio (A)/(B): 60/40), except that the antioxidant (D) was 
employed in the amount as indicated in Table 8. 
The test results are shown in Table 8. 
TABLE 8 
__________________________________________________________________________ 
Tensile 
Bonding strength 
strength retention 
Amount of against 
T-bonding 
upon 
Example Antioxidant (D) 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
(%) resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
47 1.0 4 10.7 18.7 63 
50 0.5 4 10.3 18.5 57 
51 1.5 4 10.1 18.0 60 
52 2.0 4 9.3 17.8 65 
53 3.0 4 8.5 17.5 55 
54 0 4 10.3 17.3 59 
__________________________________________________________________________ 
EXAMPLES 55 TO 58 AND COMATIVE EXAMPLES 19 AND 20 
In each of Examples 55 to 58 and Comparative Examples 19 and 20, a 
rubber-reinforcing aromatic polyamide multifilament yarn was produced by 
the same procedures as in Example 47, except that the heat-treating step 
was carried out at the temperature and for the time as shown in Table 9. 
The test results are shown in Table 9. 
TABLE 9 
__________________________________________________________________________ 
Tensile 
Heat treating Bonding strength 
step strength retention 
Temper- against 
T-bonding 
upon 
Example ature 
Time 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
(.degree.C.) 
(sec.) 
resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
47 150 120 4 10.7 18.9 63 
55 100 100 2 6.2 15.3 70 
56 150 150 3 7.4 16.5 67 
57 150 200 3 8.5 17.9 65 
58 150 180 4 8.0 19.3 65 
Comparative 
19 90 90 1 3.5 19.0 71 
Example 
20 150 270 4 8.9 18.3 49 
__________________________________________________________________________ 
EXAMPLES 59 TO 62 AND COMATIVE EXAMPLES 21 TO 23 
In each of Examples 59 to 62, an aromatic polyamide multifilament yarn 
having a yarn count of 1,500 deniers/1,000 filaments, and available under 
the trademark of Technola T-200, from Teijin Ltd., was used. 
A treating liquid was prepared in the following manner. A first liquid 
rubber component (A) consisting of a liquid 1,2-type polybutadiene glycol 
having a molecular weight of 3,000, and available under the trademark of 
G-3000, from Nagase Kasei Kogyo K.K., was mixed with a solution of 50% by 
weight of a second liquid rubber component (B) consisting of a liquid 
1,2-type polybutadiene diisocyanate having a molecular weight of 3,000, in 
a solvent consisting of methylethylketone; which solution was available 
under the trademark of TP1001, from Nihon Soda Kogyo K.K., in a mixing 
weight ratio (A)/(B) as shown in Table 10, and the mixture was dissolved 
in toluene. 
The solution was mixed with an antiaging agent (E) consisting of 
2,2,4-trimethyl-1,2-dihydoquinone polymer, which was available under the 
trademark of Antigen RD-G, from Sumitomo Kagaku Kogyo K.K., in an amount 
of 1% based on the total dry solid weight of the first and second liquid 
rubber components (A) and (B), and then with an additional epoxy component 
(C) consisting of glyceroldiglycidylether (EX313) in an amount of 5% based 
on the total dry solid weight of the liquid rubber components (A) and (B), 
to provide the treating liquid having a concentration of 20% by dry solid 
weight. 
The aromatic polyamide multifilament yarn was immersed in the treating 
liquid and squeezed at a pick up of about 10% based on the weight of the 
multifilament yarn. 
The resultant impregnated multifilament yarn was dried at a temperature of 
150.degree. C. for 2 minutes and heat-treated at a temperature of 
250.degree. C. for one minute to cure the rubber components (A) and (B) 
and the additional epoxy component (C). 
The heat treated multifilament yarn was doubled, and the doubled yarn was 
twisted at a twist coefficient K of 1.0. 
Separately, an adhesive agent was prepared by mixing one part by weight of 
a resorcinol-formaldehyde resin having a molar ratio of resorcinol to 
formaldehyde of 1:6, with 5 parts by weight of a vinyl 
pyridine-styrene-butadiene terpolymer rubber latex (dry solid content: 5% 
by weight). 
The adhesive agent was applied to the twisted yarn so that the adhesive 
agent was attached in a dry solid amount of 5% based on the weight of the 
twisted yarn, dried at a temperature of 130.degree. C. for 2 minutes and 
cured at a temperature of 240.degree. C. for 2 minutes. 
The resultant rubber-reinforcing multifilament yarn was subjected to the 
above-mentioned tests. 
In each of Comparative Examples 21 to 23, the same procedures as in Example 
59 were carried out except that (i) in Comparative Example 21, the 
impregnating step with the treating liquid was omitted, (ii) in 
Comparative Example 22, the second liquid rubber component (B), the 
antiaging agent (E), and the additional epoxy component (C) were omitted 
from the treating liquid, and (iii) in Comparative Example 8, the first 
liquid rubber component (A), the antiaging agent (E) and the additional 
epoxy component (C) were omitted from the treating liquid. 
The test results are shown in Table 10. 
TABLE 10 
__________________________________________________________________________ 
Performance of resultant rubber-reinforcing yarn 
Bonding 
strength Tensile strength 
against 
T-bonding 
retention upon 
Example Weight ratio 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
(A)/(B) 
resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
59 90/10 2 4.9 12.5 61 
60 60/40 4 10.5 17.7 65 
61 40/60 4 10.1 17.2 63 
62 10/90 3 5.8 13.7 61 
Comparative 
21 None 1 10.3 17.3 59 
Example 
22 100/0 1 10.6 17.6 61 
23 0/100 2 5.3 13.2 62 
__________________________________________________________________________ 
Table 10 shows that the rubber reinforcing multifilament yarns of Examples 
59 to 62 exhibited a satisfactory fraying resistance of individual 
filaments, a high bonding strength against peeling, a high T-bonding 
strength and a satisfactory tensile strength retention in the fatigue 
test. 
EXAMPLES 63 TO 67 
In each of Examples 63 to 67, a rubber-reinforcing aromatic polyamide 
multifilament yarn was produced by the same procedures as in Example 60 
(weight ratio (A)/(B): 60/40), except that the antiaging agent was 
employed in the amount as shown in Table 11. 
The test results are shown in Table 11. 
TABLE 11 
__________________________________________________________________________ 
Tensile 
Bonding strength 
strength retention 
Amount of against 
T-bonding 
upon 
Example Antiaging agent 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
(%) resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
60 1.0 4 10.5 17.7 65 
63 0.5 4 10.3 18.5 61 
64 1.5 4 9.8 17.0 62 
65 2.0 4 8.9 17.3 63 
66 3.0 4 7.3 17.1 57 
67 0 4 10.3 17.3 59 
__________________________________________________________________________ 
EXAMPLES 78 TO 71 AND COMATIVE EXAMPLES 24 AND 25 
In each of Examples 68 to 71 and Comparative Examples 24 and 25, a 
rubber-reinforcing aromatic polyamide multifilament yarn was produced by 
the same procedures as in Example 60, except that the heat-treating step 
was carried out at the temperature and for the time as shown in Table 12. 
The test results are shown in Table 12. 
TABLE 12 
__________________________________________________________________________ 
Tensile 
Heat treating Bonding strength 
step strength retention 
Temper- against 
T-bonding 
upon 
Example ature 
Time 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
(.degree.C.) 
(sec.) 
resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
60 150 150 4 10.5 17.7 65 
68 100 100 2 5.7 14.8 71 
69 150 150 3 6.8 15.7 66 
70 150 200 3 8.3 17.5 67 
71 150 180 4 8.1 19.1 66 
Comparative 
24 90 90 1 3.3 13.5 71 
Example 
25 150 270 4 8.4 17.4 49 
__________________________________________________________________________ 
EXAMPLES 72 to 77 
In each of Examples 72 to 76, an aromatic polyamide multifilament yarn 
having a yarn count of 1,500 deniers/1,000 filaments, and available under 
the trademark of Technola T-200, from Teijin Ltd., was used. 
A treating liquid was prepared in the following manner. A first liquid 
rubber component (A) consisting of a liquid 1,2-type polybutadiene glycol 
a molecular weight of 3,000, and available under the trademark of G-3000, 
from Nihon Soda Kogyo K.K., was mixed with a solution of 50% by weight of 
a second liquid rubber component (B) consisting of a liquid 1,2-type 
polybutadiene diisocyanate having a molecular weight of 3,000, in a 
solvent consisting of methylethylketone; which solution was available 
under the trademark of TP1001, from Nihon Soda Kogyo K.K., in a mixing 
weight ratio (A)/(B) as shown in Table 13, and the mixture was dissolved 
in toluene. 
The mixture was added with a rubber antiaging agent (E) consisting of 
2,2,4-trimethyl1,2-dihydroquinone polymer (Antigen RD-G) in an amount of 
1% based on the total dry solid weight of the liquid rubber components (A) 
and (B), and then with an additional epoxy component (C) consisting of 
glyceroldiglycidylether (EX-313) in an amount of 5% based on the total dry 
solid weight of the components (A) and (B), to provide the treating liquid 
having a concentration of 20% by dry solid weight. 
The aromatic polyamide multifilament yarn was immersed in the treating 
liquid and squeezed at a pick up of about 10% based on the weight of the 
multifilament yarn. 
The resultant impregnated multifilament yarn was dried at a temperature of 
150.degree. C. for 2 minutes and heat-treated at a temperature of 
250.degree. C. for one minute to cure the rubber components (A) and (B). 
The heat treated multifilament yarn was primarily twisted in Z direction at 
the twist coefficient K as indicated in Table 13. The primarily twisted 
multifilament yarn was doubled and finally twisted in S direction at a 
twist coefficient K of 2.0. 
Separately, an adhesive agent was prepared by mixing one part by weight of 
a resorcinol-formaldehyde resin having a molar ratio of resorcinol to 
formaldehyde of 1:6, with 5 parts by weight of a vinyl 
pyridine-styrene-butadiene terpolymer rubber latex (dry solid content: 5% 
by weight). 
The adhesive agent was applied to the twisted yarn so that the adhesive 
agent was attached in a dry solid amount of 5% based on the weight of the 
twisted yarn, dried at a temperature of 130.degree. C. for 2 minutes and 
cured at a temperature of 240.degree. C. for 2 minutes. 
In Example 77, the same procedures as in Example 72 were carried out except 
that in the twisting step, the primary twisting operation was omitted. 
The resultant rubber-reinforcing multifilament yarns were subjected to the 
above-mentioned test. 
The test results are shown in Table 13. 
TABLE 13 
__________________________________________________________________________ 
Tensile 
Twist Bonding strength 
coefficient K 
strength retention 
in primary against 
T-bonding 
upon 
Example twisting 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
operation 
resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
72 0.1 4 10.6 17.9 58 
73 0.2 4.sup.(*)1 
11.6 18.5 63 
74 0.5 4.sup.(*)1 
11.3 19.3 68 
75 1.0 4.sup.(*)1 
11.4 18.2 65 
76 1.1 4 10.7 17.9 58 
77 -- 3 10.5 17.8 57 
__________________________________________________________________________ 
Note: 
.sup.(*)1... Extremely excellent in fraying resistance 
Table 13 shows that in the twisting step the primary twisting operation at 
a twist coefficient K of 0.2 to 1.0 (Examples 73 to 75) effectively 
enhanced the fraying resistance, the bonding strength against peeling, the 
T-bonding strength and the retention in tensile strength of the 
rubber-reinforcing multifilament yarn. 
EXAMPLES 78 TO 83 
In each of Examples 78 to 83, a rubber-reinforcing aromatic polyamide 
multifilament yarn was produced by the same procedures as in Example 72, 
except that in the treating liquid for the impregnating step, the first 
liquid rubber component (A) consisted of a liquid 1,4-type polybutadiene 
diepoxide (trademark: R-45 EPT, Nagase Kasei Kogyo K.K.) having a 
molecular weight of 3,000, and in Examples 78 to 82, the primary twisting 
operation was carried out at the twist coefficient as indicated in Table 
14, and in Example 83, the primary twisting operation was omitted. 
The test results are shown in Table 14. 
TABLE 14 
__________________________________________________________________________ 
Performance of resultant rubber-reinforcing yarn 
Twist Bonding 
coefficient 
strength Tensile strength 
in primary against 
T-bonding 
retention upon 
Example twisting 
Fraying 
peeling 
strength 
fatiguing 
No. Item 
operation 
resistance 
(kg/5 cords) 
(kg/cm) 
(%) 
__________________________________________________________________________ 
Example 
78 0.1 4 10.7 18.0 59 
79 0.2 4.sup.(*)1 
11.8 18.6 65 
80 0.5 4.sup.(*)1 
11.5 19.5 70 
81 1.0 4.sup.(*)1 
11.6 18.5 68 
82 1.1 4 10.8 18.2 59 
83 -- 3 10.6 17.9 58 
__________________________________________________________________________ 
Table 14 shows that the primary twisting operation in the twisting step at 
a twist coefficient of 0.2 to 1.0 (Examples 79 to 81) effectively enhanced 
the performances of the rubber-reinforcing multifilament yarn.