DESCRIPTION
Titleofthe Invention: FIBERCORDFORREINFORCEMENT ANDMETHOD
FOR PRODUCING THE SAME
Technical Field
[OOOl]
The present invention relates to a fiber cord for
reinforcement. It more specifically relates to a fiber cord
for reinforcement having significantly improved fraying
resistance, and also to a method for producing the same.
Background Art
[0002]
In recent years, to deal with the global environmental
destruction, petroleum resource depletion, andlike problems,
a great amount of attention has been paid to energy saving and
energy substitution for automobiles, electric appliances, etc
In particular, with automotive weight reduction for improving
the fuelefficiency, theneed forthe weight and size reduction
of components is rapidly increasing. As such components,
fiber-reinforced composite materials have been widely used.
[0003]
However, such composite materials containing fibers for
reinforcement have the problem that when the material is once
shaped and then cut, the fibers are frayed at the cut face.
This phenomenon is especially prominent in fiber-reinforced
rubber composite materials such as belts. Because the rubber
forming the matrix of the composite is prone to deformation,
high-strength fibers for reinforcement, which hardly follow
the deformation, are exposed at the end face of the composite
material, and this is likelyto cause the problematic fraying.
[0004]
As one technique forreducingsuch fraying, amethodthat
treats a fiber with a solvent-based adhesive is known (e.g.,
PTL 1 and PTL 2). However, such organic-solvent-based
adhesivetreatmentshaveproblemsinthataheavyloadisplaced
on the safety or working environment, and also the costs for
adhesivetreatmentfacilities, recovery/wasteliquiddisposal,
and peripheral facilities thereof are extremely high.
' [0005]
Thus, in order to deal with the above problems, a method
for producing an adhesive-treated fiber using a water-based
adhesive has been tried. For example, PTL 3 proposes a fiber
cord for reinforcement, in which a first layer of the fiber
cord is treated with a water-based adhesive including a
water-based urethane resin, an epoxy compound, a blocked
polyisocyanate, and a rubber latex, and a second layer is
treated with a resorcin-formalin-latex (RFL)-based adhesive.
[ 0 0 0 6 ]
However, with these water-based techniques, under the
present circumstances, the high-level adhesion, fraying
resistance, and fatigue resistance required for automotive
transmission belts, etc., have not been achievedtothe levels
of solvent-based techniques.
PTL 1: JP-A-9-158989
PTL 2: JP-A-11-81152
PTL 3: JP-A-2003-221787
Summary of the Invention
Technical Problem
[00071
The invention has been accomplished in view of the above
background problems and art. An object of the invention is
to provide a fiber cord for reinforcement having significantly
improved fraying resistance and being excellent in adhesion
to the matrix and fatigue resistance (durability), and also
a method for producing the same.
Solution to Problem
The fiber cord for reinforcement of the invention is a
fibcrcordforreinforcementhavinganadhesivetreatmentagent
attached to the surface thereof, characterized in that the
fiber cordincludes, in an inner layer part thereof, a compound
A1 having a molecular weight of less than 1,000 and a smaller
amount of a compound B1 than the compound AI, the compound A1
being an aromatic compound or a compound containing an
a-dicarboxylic acid component, the compound B1 being an
a l i p h a t i c compound or an a l i c y c l i c compound.
[0009]
Further, it is p r e f e r a b l e t h a t the adhesive treatment
agent is a resorcin-formalin-latex (RFL)-based adhesive, the
f i b e r cord includes a twisted multifilament f i b e r o r a
s y n t h e t i c f i b e r , and the aromatic compound is a h e t e r o c y c l i c
compound. I n a d d i t i o n , it is preferable t h a t t h e compound A1
is located only i n the inner l a y e r p a r t of the f i b e r cord, a
compound having a hexamethylene diisocyanate ( H D I ) trimer
s t r u c t u r e is present i n the inner layer p a r t of the f i b e r cord,
and no l a t e x is present i n the i n n e r l a y e r p a r t of the f i b e r
cord.
[OOlO]
In addition, the method f o r producing a f i b e r cord f o r
reinforcement o f t h e i n v e n t i o n i s amethodforproducingafiber
cord for reinforcement, including t r e a t i n g a f i b e r cord i n two
stages with a pre-treatment l i q u i d and an adhesive treatment
l i q u i d . Themethod is c h a r a c t e r i z e d i n t h a t the pre-treatment
l i q u i d contains two kinds o f blockedisocyanate compoundsthat
a r e a compound A2 and a smaller amount of a compound B2, the
compoundA2havinganisocyanate groupblockedwithanaromatic
compound or a compound containing an a-dicarboxylic acid
component, the compound Bz having an isocyanate group blocked
withanaliphaticcompoundoranalicycliccompound, anda f i b e r
cord havingthe pre-treatment liquid attachedthereto is once
subjected to a heat treatment, and then the adhesive treatment
liquid is attached thereto, followed by a drying treatment.
[OOll]
Further, it is preferable that the aromatic compound is
a heterocyclic compound, and the unblockingtemperature ofthe
compound A2 is lower than the unblocking temperature of the
compound Bz. In addition, it is preferable that the compound
A2 has a hexamethylene diisocyanate (HDI) trimer structure,
and the compound BE has an isocyanate group blocked with an
aliphatic compound or an alicyclic compound.
Advantageous Effects of the Invention
[0012]
According to the invention, a fiber cord for
reinforcement having significantly improved fraying
resistance and being excellent in adhesion to the matrix and
fatigue resistance (durability) andamethod forproducingthe
same are provided.
Description of Embodiments
LOO1 31
he fiber cord for reinforcement of the invention has
an adhesive treatment agent attached to the surface thereof.
Theadhesivetreatmentagenthereinisnotparticularlylimited
and selected fromthose suitable for a structure (matrix) to
be reinforced with fibers. However, more specifically, for
5
example, i n the case where the matrix is a rubber or t h e l i k e ,
it is p r e f e r a b l e t h a t the adhesive treatment agent is a
resorcin-formalin-latex (RFL)-based adhesive.
Then, t h e f i b e r formingthe f i b e r cord for reinforcement
used i n the invention is i n a fibrous form to reinforce the
matrix of the s t r u c t u r e , and it is p r e f e r a b l e t h a t t h i s f i b e r
is a s y n t h e t i c f i b e r . More s p e c i f i c a l l y , f o r example, it is
preferable t h a t the f i b e r is a s y n t h e t i c fibermade of a t l e a s t
one kind of s y n t h e t i c r e s i n selected from polyesters,
polyarylates, a l i p h a t i c polyamides, vinylon, wholly aromatic
polyamides, polyparabenzobisoxazole, and carbon f i b e r s .
Amongthem, organicfibersarepreferable, andpolyester f i b e r s
and wholly aromatic polyamide f i b e r s are p a r t i c u l a r l y
p r e f e r a b l e . Examples of p r e f e r r e d p o l y e s t e r f i b e r s include'
a polyethylene t e r e p h t h a l a t e f i b e r , a polybutylene
t e r e p h t h a l a t e f i b e r , andapolyethylene-2,6-naphthalate f i b e r
Examples ofpreferredwhollyaromaticpolyamide f i b e r s i n c l u d e
riholly aromatic para-type polyamide f i b e r s and meta-type
polyamide f i b e r s . However, i n terms of reinforcement,
high-strength para-type aromatic polyamide f i b e r s a r e
preferable. In addition, i n terms of the balance between
strengthandadhesion, f u r t h e r , it is p r e f e r a b l e t h a t the f i b e r
forming t h e f i b e r cord is a t l e a s t one kind of polyester f i b e r
selected from polyethylene t e r e p h t h a l a t e ,
polyethylene-2,6-naphthalate, and the like.
[0015]
As the applications of the fiber cord for reinforcement
of the invention, it is preferable that the fiber cord is used
as a rubber fiber composite, particularly a cord of a rubber
belt. In particular, in the case where the fiber cord is used
as a belt cord, the use of the above fiber makes the fiber cord
more optimal in terms of tensile strength performance,
dimensional stability, durability, and general versatility.
' (00161
Here, it is preferable that the fiber cord for
reinforcement of the invention is a s~ngley arn or an assembly
of several yarns. Then, it is also preferable that a single
yarn forming the fiber cord for reinforcement itself is an
assembly of several fiber filaments in the form of a bundle.
It is preferable that the fineness ofthe single yarn (assembly
of fiberfilaments) is 500to 4,00Odtex, stillmorepreferably
1,000 to 3,000 dtex. Such a yarn is particularly effective
in terms of handleability in the steps of twisting, adhesive
treatment, and shaping. It is preferable that the total
fineness ofthe fiber cord for reinforcement ofthe invention,
which is an assembly of such yarns, is 500 to 15,000 dtex.
- Incidentally, no particular limitations are imposed on the
number of filaments of the fiber, its cross-sectional shape,
the physical properties of the fiber, the microstructk-e, the
polymer p r o p e r t i e s (molecu,lar weight, terminal functional
groupconcentration, e t c . ) , a d d i t i v e s i n the polymer, e t c . In
addition, it is a l s o preferable t h a t t h e f i b e r yarn has been
previously pre-treated with an epoxy r e s i n , a urethane r e s i n ,
or the l i k e i n the stage of yarn-making or a f t e r yarn making.
[00171
.The f i b e r cord f o r reinforcement used i n the invention
is an assembly of one or more such yarns, and it is s t i l l more
preferablethatitisatwistedcord. Further, it i s p r e f e r a b l e
t h a t t h e f i b e r cord is obtained by aligning and twisting one
or more such yarns ( f i r s t t w i s t i n g ) and then aligning and
twisting two or more such twisted yarns (second t w i s t i n g ) .
Twistingparticularlyimprovesthe bending f a t i g u e r e s i s t a n c e
and t h e l i k e . Here, it is preferable t h a t the number of t w i s t s
represented by the following equation (1) is within a range
such t h a t the t w i s t c o e f f i c i e n t K s a t i s f i e s 300 t o 1,200, more
preferably K = 500 t o 1,000. When such a number of t w i s t s is
s a t i s f i e d , the bending fatigue r e s i s t a n c e is s a t i s f i e d while
maintainingthepenetrationofthe adhesive i n t o t h e f i b e r cord
t o exert' fraying r e s i s t a n c e .
[0018]
[Equation 1 1
K = T x -\ID (1)
[00191
(wherein K: t w i s t c o e f f i c i e n t , T: the number of t w i s t s per m
[twists/ml , D: total fineness [dtex] )
When the twist coefficient Kislessthan 300, thebending
fatigue resistance and adhesion tend to decrease. Meanwhile,
in the case where K is more than 1,200, there is a tendency
that the strength decreases, and also the treatment agent
(first adhesive treatment agent) is unlikely to sufficiently
penetrate into the fiber cord, resulting in a decrease in
fraying resistance.
[0020]
Incidentally, in the case where the fiber cord for
reinforcement of the invention is obtained by aligning and
twisting one or more fiber yarns (first twisting) and then
aligning and twisting two or more such twisted yarns (second
twisting) as described above, it is preferable that the first
t w i s t i n g a n d s e c o n d t w i s t i n g b o t h s a t i s f y t h e t ~ r i s t c o e f f i c i e n t
K = 300 to 1,200, and the twist coefficients of the first
twisting and the second twisting may be the same or different.
[00211
The fiber cord for reinforcement of the invention is a
fibercordforreinforcementhavinganadhesivetreatmentagent
attached to the surface of such a fiber cord. Then, the fiber
cord includes, in the inner layer part thereof, a compound Al
having a molecular weight of less than 1,000 and a smaller
amount of a compound B1 than the compound Al. Here, the compound
Al is an aromatic compound or a compound containing an
a-dicarboxylic acid component, and the compound B1 is an
aliphatic compound or an .alicyclic compound. Here, it is
preferable that the compound B1 is a compound other than the
compoundA1, which is structurally different fromthe compound
Al. More specifically, it is preferable that the compound B1
is a compound that does not contain an aromatic compound or
an a-dicarboxylic acid component.
[00221
+
Here, the compound Al present in the inner layer part
of the fiber cord of the invention is a compound having a
m o l e c u l a r ~ i e i g h t o f l e s s t h a n 1 , 0 0 0 , andis anaromaticcompound
or a compound containing an &-dicarboxylic acid component.
Such compounds are structurally prone to resonance because of
the presence of a double bond. In addition, here, aromatic
compounds are not limited to ordinary aromatic compounds
composed only of carbon atoms. Heterocyclic compounds having
a cyclic structure formedbynitrogenorlike atomsinaddition
tocarbonandhavingaromaticproperties, that is, heterocyclic
aromatic compounds, are also preferable. Specific examples
phenols such as phenol, thiophenol, cresol, and resorcinol,
aromatic secondary amines such as diphenylamine andxylidine,
heterocyclic compounds such as dimethylpyrazole, and
a-dicarboxylicacids such as diethylmalonic acid. Among them,
dimethylpyrazole, which is a heterocyclic aromatic compound,
is particularly preferable.
100231
In addition, the compound B1 present inside the fiber
cord in an amount smaller than that of the compound A1 (weight
ratio) i's an aliphatic compound or alicyclic compound having
no aromatic properties. Such compounds B1 are ordinary
compounds that do not have a resonance structure like the
compoundAl. Inaddition, with respect tothemolecular weight
of the compound B1, similarly to the compound Al, a compound
having a molecular weight of less than 1,000 is preferable.
More specifically, examples of compounds particularly
preferable as the compound Blinclude phthalicimides, lactams
such as caprolactam and valerolactam, oximes such as
methylethylketoxime, and aliphatic compounds such as acidic
sodiumsulfite. Among them, E-caprolactam, which is a lactam,
is particularly preferable. Further, in the case where
dimethylpyrazole is used as the compound Al, when a lactam is
combined therewith as the compound B1, the impregnation of the
agent into the fiber is excellent, and the performance of the
fiber cord is particularly improved.
[0024]
In the inner layer part of the fiber cord for
reinforcement of the invention, the compounds Al and B1 each
having a m o l e c u l a r w e i g h t o f l e s s t h a n 1 , 0 0 0 as describedabove
are contained, and further it is preferable that the molecular
weights of these compounds are each 60 or more and l e s s than
600.
LO0251
In addition, it is necessary t h a t the content of the
compound Al i n t h e f i b e r cord i n n e r l a y e r part is higher than
the content of the compound B1 (weight r a t i o ) , and f u r t h e r it
is preferable t h a t the abundance r a t i o between the compound
Al and the compound B1 (weight r a t i o ) , A l / B l r a t i o , is within
a range of 60/40 t o 95/5.
LO0261
Here, when the s o l i d s weight r a t i o of compound
A1/compoundB~isincreased,the f i l m f o r m a t i o n i n s i d e the f i b e r
bundletendstotakeplacemore e f f e c t i v e l y . Thus, a firrnfilm
is formed, and, when t h e f i b e r cord of the invention is
eventually used f o r a composite, improved fraying r e s i s t a n c e
is provided. This a t t r i b u t e s t o the f a c t t h a t t h e compound
Al, which is a compound prone to having a resonance s t r u c t u r e ,
has high r e a c t i v i t y and is e f f e c t i v e i n film formation. That
is, s p e c i f i c a l l y , it is p r e f e r a b l e t h a t t h e abundance r a t i o
of A1/B1 is a t l e a s t 60/40. Meanwhile, in the case where the
s o l i d s weight r a t i o of compound Al/compound B2 is too high,
there is a tendency t h a t the f i l m inside the f i b e r is l i k e l y
t o be hard and b r i t t l e , and the bending fatigue r e s i s t a n c e and
d u r a b i l i t y t e n d t o decrease. It is preferable t h a t the s o l i d s
weight r a t i o of compound Al/compound B2 is 95/5 or l e s s . It
is p r e f e r a b l e t h a t such compounds A1 and B1 are attached i n an
amountwithinarangeof0.0001to0.2wt% r e l a t i v e t o t h e f i b e r .
[0027]
I n a d d i t i o n , in the inner l a y e r p a r t of the f i b e r cord
for reinforcement of the invention, in addition t o these
r e l a t i v e l y low-molecular compounds, it is preferable t h a t
high-molecular compounds derived from epoxy compounds and t h e
l i k e a r e a l s o present. Further, with respect t o the compounds
A L a n d B 1 p r e s e n t i n s i d e t h e f i b e r b u n d l e , it is preferable t h a t
the t o t a l amount thereof attached is within a range of 0.01
w t % t o 2 w t % r e l a t i v e totheamount (weight) of other components
a t t a c h e d t o t h e f i b e r , suchas high-molecularcompounds. When
such high-molecular compounds, t h a t is, r e s i n - l i k e substances,
a r e present i n large amounts i n the inner layer of the f i b e r
bundle, high bundling p r o p e r t i e s can be obtained. When the
abundances of the compounds A1 and B1 a r e too high, conversely,
the adhesion t o the matrix tends t o decrease, while when the
abundances are too low, there is a tendency t h a t the f i b e r cord
is d i f f i c u l t t o bundle, r e s u l t i n g i n a decrease in fraying
r e s i s t a n c e .
[00281
Here, as high-molecular compounds present in the f i b e r
bundle i n n e r l a y e r of the invention, epoxy compounds, l a t e x
rubbers, and the l i k e are p r e f e r a b l e . As epoxy compounds, it
is p r e f e r a b l e t h a t an epoxy compound having an epoxy group is
attached to the fiber surface, followed by a heat treatment
or the like to increase the molecular weight. Specific
examples thereof include reaction products between a
polyalcohol such as ethylene glycol, glycerol, sorbitol,
pentaerythritol, or polyethylene glycol and a
halogen-containing epoxide such as epichlorohydrin; reaction
products between a polyphenol such as resorcin,
bis(4-hydroxyphenyl)dimethylmethane, a phenol-formaldehyde
resin, or a resorcin-formaldehyde resin and a
halogen-containing epoxide as described above; and
polyepoxide compounds prepared by oxidizing an unsaturated
compound with peracetic acid, hydrogen peroxide, or the like,
that is, 3,4-epoxycyclohexene epoxide,
bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, andthe like.
Among them, a reaction product between a polyalcohol and
epichlorohydrin, that is, a polyglycidyl ether .compound of a
polyalcohol, develops excellent performance and thus is
particularly preferable. It is preferable that the ratio
betweenthe epoxy compoundandthetotalamount ofthecompounds
Al and B1 (epoxy compound) / (compound A1 + compound B1) is within
a range of 1/2 to 6/1.
100291
Further, in order to facilitate adhesion to the surface
adhesive layerortothematrixcomponent ofthe final composite
material, it is preferable that an isocyanate component is
containedintheinnerlayerofthe fiber cord. Inparticular,
in order to suppress deactivation during the process, it is
preferable that an isocyanate component derived fromablocked
polyisocyanate compound is contained.
[0030]
Further, in the invention, it is preferable that the
isocyanate component is derived from a compound having a
hexamethylene diisocyanate (HDI) trimer structure represented
by the following chemical structural formula (I).
[0031]
[Chemick Formula 11
[0032]
As shown in the above chemical structural formula (I),
this compound is a compound having, as its basic structure,
a trimer structure in which three terminal NCO groups of the
hexamethylene diisocyanate (HDI) form a cyclic structure.
Further, as each trimer structure, as shown in the following
chemical structural formula (11) , for example, a compound
condensed to further increase the functionality is also -
preferable. Here, R of chemical structural formula (11) can
be selected from polyglycols, such as polyethylene glycol,
without impairingthe affinity for water and heat resistance.
[00331
[Chemical Formula 21
LOO341
In addition, as the isocyanate component, it is
preferable that the number of NCO functional groups present
in the molecule is three or more, whereby the adhesion can be
further improved.
As other isocyanate components, components derived from
adiphenylmethane diisocyanate (MDI) compoundare preferable.
Components derived from a compound having a hexamethylene
diisocyanate ( H D I ) trimer structure described above are
flexible, while components derived from a diphenylmethane
diisocyanate (MDI) compound are rigid. Accordingly, when
these two kinds of components are present together, a film that
is firm, dense, and also flexible is formed in the inner layer
part ofthe fiber cord. Then, the fiber cord for reinforcement
of the invention allows for more significant improvements in,
in addition to fraying resistance, bending fatigue resistance
and adhesion.
[0036]
In the fiber cord for reinforcement of the invention,
as described above, the compound Al and the compound BI are
contained in the inner layer part of the fiber cord, and the
surface of the fiber cord has attached thereto an adhesive
treatment agent. Here, the adhesive treatment agent can be
suitably changed according tothe object to be reinforced with
the fiber cord. Among them, particularly in the case where
the fiber cord of the invention is used to reinforce a rubber
product such as a belt, it is preferable to use a
resorcin-formalin-latex (RFL) -based adhesive as the adhesive
treatment agent
lo0371 .
Here, RFL-based adhesives preferable to use will be
described. It is preferable that the molar ratio between
resorcin and formaldehyde in the resorcin-formalin-rubber
latex (RFL) is within a range of 1 / 0 . 6 to 1/8, more preferably
w i t h i n a r a n g e o f 1 / 0 . 8 t o 1 / 6 . Whentheamount of formaldehyde
added is too small, the crosslinking density of the
resorcin-formalin condensate decreases, and the molecular
weight also decreases. Accordingly, the cohesive strength of
the adhesive layer may decrease, resulting in a decrease in
adhesion and also a decrease in bending fatigue resistance.
In addition, on t h e o t h e r hand, when the amount of formaldehyde
added is t o o l a r g e , the resorcin-formalin condensate tends t o
be hard due t o an increase in crosslinking d e n s i t y . Then, a t
the time of covulcanization with the adherend rubber, the
compatibilizationbetween RFL and the rubber maybe i n h i b i t e d ,
r e s u l t i n g i n a decrease i n the adhesion of t h e f i b e r cord for
reinforcement.
[0038]
I n a d d i t i o n , with respect t o the blending r a t i o between
resorcin-formalin (RF) a n d l a t e x (L) i n t h i s adhesive, theRF/L
s o l i d s w e i g h t r a t i o i s 1 / 3 t o 1 / 1 6 , m o r e p r e f e r a b l y 1 / 4 t o l / l O .
When the proportion of the rubber l a t e x is too low, the amount
of components t o be covulcanized with a rubber is small, and
thus the adhesion strength is l i k e l y t o d e c r e a s e . Ontheother
hand, when the proportion of the rubber l a t e x is too high, it
becomes d i f f i c u l t t o obtain s u f f i c i e n t strength as anadhesive
film. Further, the adhesion strength and d u r a b i l i t y tend t o
decrease, a n d a l s o t h e s t i c k i n e s s o f t h e a d h e s i v e - t r e a t e d f i b e r
cord tends t o be too high. Accordingly, gumming-up,
h a n d l e a b i l i t y d e t k r i o r a t i o n , or the l i k e may occur i n the
adhesive treatment step or shaping step, r e s u l t i n g in a
decrease i n process-passing p r o p e r t i e s .
[0039]
Further, as the l a t e x forming the RFL-based adhesive,
various latexes such as vinyl pyridine-styrene-butadiene
(VpSBR) l a t e x , chlorosulfonatedpolyethylene (CSM) l a t e x , and
polybutadiene (PB) l a t e x are usable. It i s p a r t i c u l a r l y
andPBlatex. I n a d d i t i o n , with respect t o t h e i r s o l i d s weight
r a t i o , defining the t o t a l weight of "VpSBR l a t e x and/or CSM
latex" as L1 andthe weight of "PBlatex" as L2, it is p r e f e r a b l e
t h a t the L1/L2 r a t i o is within a range of 25/75 t o 75/25
It is optimal t o use the above latexes p a r t i c u l a r l y i n
t h e c a s e w h e r e t h e f i b e r c o r d f o r reinforcement o f t h e invention
is used, among rubber reinforcement a p p l i c a t i o n s ,
p a r t i c u l a r l y f o r a transmission b e l t . Usually, i n a
compressedrubberlayerofatransmissionbelt, a1ov1-adhesion,
high-performance s y n t h e t i c rubber, such as
ethylene-a-olefin-diene rubber, chloroprene rubber,
hydrogenated n i t r i l e rubber, chlorosulfonated polyethylene
rubber, or styrene-butadiene rubber, is used. In c o n t r a s t ,
t h e f i b e r cord f o r reinforcement of the invention employs the
above cokposition and compositionalproportions, and thus has
high a f f i n i t y and c o v u l c a n i z a b i l i t y . In the invention, it is
important t o have high affinities both f o r t h e polymer forming
the f i b e r cord and for other agents, and it has become possible
to improve t h e f r a y i n g r e s i s t a n c e , bending f a t i g u e r e s i s t a n c e ,
and adhesion a t higher l e v e l s .
[0041]
It is preferable that the solids weight ratio of L1/L2
in the fiber cord of the invention is within a range of 25/75
to 75/25 as described above. Further, it is more preferable
that the solids weight ratio of L1/L2 is 30/70 to 70/30. In
the case where L1 is too low, the affinities for the polymer
forming the fiber cord and for the rubber forming the
transmission belt decrease. Accordingly, the adhesion
strength tend sto decrease, and the bending fatigue resistance
and adhesion of the final product also tend to decrease.
Meant-~hile,i n the case where L1 is too large, the unsaturated
bondingofthelatexintheadhesivetreatmentagentis reduced.
Accordingly, there is a tendency that the covulcanizability
with the rubber forming the transmission belt decreases,
resulting in decreases in bending fatigue resistance and
adhesion.
[00421
Examples of resorcin compounds used for the adhesive
treatment agent include pre-oligomerized resorcin-formalin
initial condensates and polynuclear chlorophenol-based
resorcin-formalin initial condensates prepared by
oligomerizingchlorophenol, resorcin, and formalin. Theymay
be used alone or in combination as necessary.
too431
In addition, it is also preferable that a crosslinking
agent is used together with this adhesive treatment agent.
Examples of p r e f e r r e d c r o s s l i n k i n g agents t o be addedinclude
amines, ethylene urea, and blocked polyisocyanate compounds.
Considering the temporal s t a b i l i t y o f t h e treatment agent, the
i n t e r a c t i o n with the pre-treatment agent, and the l i k e , it is
p r e f e r a b l e t o use a blocked polyisocyanate compound.
[00441
It is preferable t h a t t h e proportion of a crosslinking
a g e n t , suchas ablockedpolyisocyanate, a d d e d t o t h i s adhesive
treatment agent is within a range of 0 . 5 t o 40 wt%, preferably
10 t o 30 w t % , r e l a t i v e t o the resorcin-formalin-rubber l a t e x
(RFL) . An increase in the amount added usually improves the
adhesion s t r e n g t h . Meanwhile, when the amount added is too
l a r g e , conversely, there is a tendency t h a t the compatibility
oftheadhesivewithrubbersdecreases, r e s u l t i n g i n a d e c r e a s e
i n adhesion strength to rubbers.
[00451
Further, it is p r e f e r a b l e t h a t the f i b e r cord f o r
reinforcement of the invention does not contain an organic
s o l v e n t . When an organic solve'nt is not contained, the
environment is not adversely a f f e c t e d , and it has also become
p o s s i b l e t o prevent the degradation of performance with time.
Such a f i b e r cord for reinforcement can be obtained using, f o r
example, not an organic-solvent-based treatment l i q u i d but a
water-based treatment l i q u i d .
[00461
i invention, the adhesive treatment agent is attached t o the
i
w I
I surface of the f i b e r cord, and the compound Al and the compound
d
B1 are contained i n the inner layer p a r t of the f i b e r cord.
Like t h i s , i n the f i b e r cord for reinforcement of the
1 Then, i n t h e f i b e r cord f o r reinforcement of the invention, i 1 it is p r e f e r a b l e t h a t the compound Al is not present i n the i surface of the f i b e r cord, but is located only i n the inner
layer p a r t of the f i b e r cor. When the compound A1 is located
only i n the f i b e r cord inner l a y e r p a r t , t h e r e is a tendency
t h a t the adhesion inside the f i b e r cord is improved, whereby
the bundling properties are l i k e l y to be f u r t h e r improved.
Thiseffectisparticularlyprominent~nthecasewhereanepoxy
compound is present inside the f i b e r bundle, which is
compound and the compound Al. In addition, it is p r e f e r a b l e
t h a t a compound having a hexamethylene diisocyanate ( H D I )
trimer s t r u c t u r e is present i n t h e inner l a y e r p a r t o f t h e f i b e r
cord, and no l a t e x is present i n the inner layer p a r t of t h e
f i b e r cord. The presence of a l a t e x in the f i b e r cord inner
l a y e r p a r t i n h i b i t s the a f f i n i t y between the compound Al and
epoxy and thus is undesirable. In addition, it is p r e f e r a b l e
t h a t the compoundB1is u n e v e n l y l o c a t e d i n t h e f i b e r cord inner
l a y e r p a r t . This is because the presence of the compound B1
weakens t h e i n t e r a c t i o n between the l a t e x and the compound Al.
In t h e invention, because of such a configuration of the inner
layer p a r t , moderate joining can be maintained between f i b e r
f i l a m e n t s i n t h e f i b e r c o r d i n n e r layer, a n d f u r t h e r t h e fraying
r e s i s t a n c e can be improved.
I00471
In addition, such a f i b e r cord f o r reinforcement of the
invention can be obtained by a method f o r producing a f i b e r
cord f o r reinforcement, which is another embodiment of the
~ n v e n t i o n . That is, the f i b e r cord f o r reinforcement of the
invention can be obtained by a method f o r producing a f i b e r
cord for reinforcement, i n c l u d i n g t r e a t i n g a f i b e r cord i n two
stages with a pre-treatment l i q u i d and an adhesive treatment
l i q u i d . The pre-treatment l i q u i d contains two kinds of
blocked isocyanate compounds, t h a t is, a compound A2 and a
smaller amount of a blocked isocyanate compound B2. The
compound A2 has an isocyanate group blocked with an aromatic
compound or a compound containing an a-dicarboxylic acid
component, and the compound BZ has an isocyanate group blocked
with an a l i p h a t i c compound or an a l i c y c l i c compound. A f i b e r
cord havingthe pre-treatment l i q u i d a t t a c h e d t h e r e t o is once
subjected t o a heat treatment, and then the adhesive treatment
l i q u i d is a t t a c h e d t h e r e t o , Followed by a drying treatment.
LOO481
The f i b e r forming the f i b e r cord used for the method of
the invention shouldbe, as describedabove, a f i b r o u s m a t e r i a l
for r e i n f o r c i n g the matrix of a s t r u c t u r e . Synthetic f i b e r s
are particularly preferable.
[0049]
In addition, with respect to the conEiguration of the
fiber cord for reinforcement of the invention, as described
above, it is preferable that fiber cord is a single yarn or
an assembly of several yarns. It is also preferable that the
fiber has been previously treated with an epoxy resin, a
urethane resin, orthelike inthe
yarn making. Further, it is preferable that the fiber cord
is a twisted cord. As described above, it is preferable that
the fiber cord is obtained by aligning and twisting one or more
fiber yarns (first twisting) and then aligning and twisting
two or more such twisted yarns (second twisting).
[00501
The method for producing a fiber cord for reinforcement
of the invention is a method in which, first, such a fiber cord
is treated with a pre-treatment liquid. Here, the
pre-treatment liquid contains a blocked isocyanate compound
A, (hereinafter sometimes referred to as compound Az) and a
blockedisocyanatecompoundB~ (hereinafter sometimes referred
to as compound B 2 ) , and the content of the compound A2 is lower
than the content of the compound B2. k'urther, here, it is
preferable that the isocyanate group unblocking temperature
o f t h e c o m p o u n d A ~ i ~ l o w e r t h a n t h e i s o c y a n a t c g r o u p u n b l o c k i n g
temperature of the compound Bz.
[00511
Here, a blocked polyisocyanate compound used in the
methodofthe invention is anaddition reactionproduct between
a polyisocyanate compound and a blocking agent, which is the
isocyanate protecting group. When heated, the blocked
polyisocyanate compound releases the block component to
produce an active polyisocyanate compound. In particular, a
polyisocyanatecontainingterminalisocyanategroups obtained
by a reaction between isocyanate groups (-NCO) and hydroxyl
groups (-OH) in a molar ratio of more than 1 exerts excellent
performance and thus is preferable. Examples of blocking
agents includephenols such as phenol, thiophenol, cresol, and
resorcinol, aromatic secondary amlnes such as diphenylamine
andxylidlne, heterocyclic compounds such as dimethylpyrazole,
a-dicarboxylic acids such as diethyl malonic acid, phthalic
imides, lactams such as caprolactam and valerolactam,
aliphaticcompounds suchasacidic sodiumsulfite, phenols such
as phenol, thiophenol, cresol, and resorcinol, aromatic
secondaryamines such as diphenylamine and xylidine, phthalic
imides, lactams such as caprolactam and valerolactam, oximes
such as acetoxime, methylethylketoxime, and cyclohexanone
oxime, and acidic sodium sulfite.
[0052]
Then, the blocked polyisocyanate compounds used in the
method for producing a fiber cord for reinforcement of the
invention include both ofthe blockedpolyisocyanate compound
A2 blocked with an aromatic compound or a compound containing
an a-dicarboxylic acid component and the blocked
polylsocyanate compounds Bz blockedwith an aliphatic compound
or an alicyclic compound. It is still more preferable that
the isocyanate group unblocking temperature of the compound
A2 is lower than the isocyanate group unblocking temperature
of the compound Bz. Further, it is preferable that the
unblocking temperature of the compound A2 is less than 160°C,
particularly within a range of 100 to 150°C. Meanwhile, it is
that the unblocking temperature of the compound B2
is 160°C or more, particularly within a range of 160 to 200°C.
In a d d i t i o n , i t i s p r e f e r a b l e t h a t t h e a b u n d a n c e o f t h e c o m p o u n d
A2 is higher than the abundance of the compound 82, and further
it is preferable that the solids weight ratio of compound
Az/compound B2 is 99/1 to 60/40.
[0053]
Here, an unblocking temperature refers to a temperature
at which the blocking group is released from a blocked
isocyanate by heat, whereby the isocyanate activity is
developed. As preferred conditions for the method of the
invention, first, through the first-stage heat treatment, the
blocked polyisocyanate compound A2 blocked with an aromatic
compound or a compound containing an a-dicarboxylic acid
component is unblocked and crosslinked. Then, through the
subsequent second-stage heat treatment, the blocked
polyisocyanate compound B2 is unblocked, and the
compound-B2-derived compound is crosslinked with the
crosslinkedisocyanate derived fromthe compoundA2. Further,
it is preferable that the first-stage heat treatment is a
low-temperature heat treatment, and the second-stage heat
treatment is ahigh-temperature heat treatment. In themethod
ofthe invention, crosslinkingis performedin two stages like
this, whereby a tough, dense film of the pre-treatment liquid
(first bath adhesive) can be formed inside and on the surface
ofthe fiber cord. Accordingly, the fiber cordcanbe provided
with enhanced fraying resistance, bending fat~guer esistance,
and adhesion. In particular, the obtained fiber cord is
optimal for rubber reinforcement applications, particularly
for use as a cord for a transmission belt.
[0054]
Here, with respect to the difference in unblocking
temperature between the compound A2 and the compound B2, the
greater the better. It is preferable that the difference in
unblocking temperature between the compounds A2 and BZ [=
(unblocking temperature of the compound B2) - (unblocking
temperature of the compound A211 is 30°C or more. When the
temperature difference is sufficient, the two-stage
isocyanate crosslinking reaction can take place more easily.
When the temperature difference is too small, this results in
a competing reaction, i n which the c r o s s l i n k i n g r e a c t i o n s of
the compound A2 and the compound B2 t a k e p l a c e a t the same time.
As a r e s u l t , ittendstobedifficulttocontrolthe crosslinked
s t r u c t u r e . I n a d d i t i o n , t h i s is l i k e l y t o expose the
difference i n the strength of the pre-treatment l i q u i d film
between the inner and o u t e r l a y e r s of the f i b e r cord due t o
the difEerence i n heat d i s t r i b u t i o n . I n such a case, the
fraying r e s i s t a n c e and bending fatigue r e s i s t a n c e tend to
decrease. More s p e c i f i c a l l y , as unblockingtemperatures, it
is preferable t h a t the unblocking temperature o f t h e compound
A2 is 110 t o 130°C, and the unblocking temperature of the
compound Bp is 160°C t o 180°C.
[0055]
The compound A2 used i n the method of the invention is
the above compound A2 and has an isocyanate group blocked with
anaromaticcompoundoracompoundcontainingana-dicarboxylic
acid component. Further, as the aromatic compound, a
heterocyclic compound having a c y c l i c s t r u c t u r e containing
nitrogenorlikeatomsinadditiontocarbonatomsis preferable,
and it is p a r t i c u l a r l y p r e f e r a b l e t h a t the aromatic compound
is a heterocyclic aromatic compound such as dimethylpyrazole
( D M P ) . As the compound containing an a-dicarboxylic acid
component, a compound blocked with d i e t h y l malonate i s
preferable. Such a compound A2 is prone t o having a resonance
s t r u c t u r e , allowing f o r unblocking a t a lower temperature.
L [00561
In addition, the compound B2 used in the method of the
invention is the above compound B2 and has an isocyanate group
blocked with an aliphatic compound or an alicyclic cornpound.
More specifically, those blocked with an oxime such as
methylethylketoxime or a lactam such as 6-caprolactam are
preferable.
Inaddition, theunblockingtemperatureis significantly
affected by the block-forming compound structure. In the
method of the invention, it is particularly preferable that
the block structure of the compound A2 is a dimethylpyrazole
(DMP) block structure, and the block structure of the compound
B2 is an &-caprolactam block structure.
[0058]
In.addition, in the invention, it is preferable that the
blocked polyisocyanate compound A2 is composed of a compound
having a hexamethylene diisocyanate (HDI) trimer structure
represented by the following chemical structural formula (I) .
[0059]
[Chemical Formula 31
[0060]
As shown in the above chemical structural formula (I),
this blocked polyisocyanate compound is a compound having, as
its basic structure, atrimer structure inwhichthree terminal
NCO groups of the hexamethylene diisocyanate (HDI) form a
cyclic structure. It is also preferable that each trimer
structure is, as shown in the following chemical structural
formula (11), for example, a condensedcompoundhaving further
increased functionality. Here, R of chemical structural
formula (11) can be selected from polyglycols, such as
polyethylene glycol, without impairingthe affinity for water
and' heat resistance.
[0061] '
[Chemical Formula 41
[0062]
In addition, in the invention, it is preferable that the
blocked isocyanate compound A2 is such that the number of
functional groups present in the molecule after unblocking is
three or more. In the case where the number of functional
groups is two or less, the crosslinking reactivity with the
pre-treatment liquid and the reactivity to the adhesive
treatment liquid tend to be insufficient. In particular, in
thecasewherethe fiber cord for reinforcement ofthe invention
is used for rubber reinforcement, suchas abeltcorematerial,
a resorcin-formalin-latex (RFL)-based adhesive is usually
used as the adhesive treatment liquid; however, there is a
tendency that with the small amount of resorcinol-derived
hydroxyl groups contained in RFL alone, the reactivity is
likely to be insufficient.
100631
Meanwhile, as the blocked polyisocyanate compound Bz,
an &-caprolactam-blocked diphenylmethane diisocyanate (MDI)
compound is particularly preferable. In the invention, an
epoxy compound and a flexible blockedpolyisocyanate compound
AZ are crosslinkedthroughthe first-stage heat treatment, and
then a blocked polyisocyanate compound B2 having a rigid MDI
structure is furthercrosslinkedthroughthe second-stageheat
treatment. As a result, a pre-treatment liquid film, which
is particularly firm, dense, and also flexible, is formed
inside and also on the surface layer of the fiber cord. Then,
it has become possible to achieve significant improvements in
fraying resistance, bending fatigue resistance, and adhesion,
which have been difficult to achieve by the conventional
aqueous adhesive treatment.
[0064 ]
In addition, in the method for producing a fiber cord
for reinforcement of the invention, it is preferable that the
pre-treatment liquid contains an epoxy compound in addition
to the above two kinds of blocked isocyanate compounds.
[ 0 0 6 5 ]
Here, as the epoxy compound used in the invention, a
compound having at least two epoxy groups in one molecule is
preferable. In particular, a compound containing at least 2
gequivalents of epoxygroups per kgof compound is preferable.
More specifically, examples thereof include reaction products
between a polyalcohol such as ethylene glycol, glycerol,
sorbitol, pentaerythritol, or polyethylene glycol and a
halogen-containing epoxide such as epichlorohydrin; reaction
products between a polyphenol such as resorcin,
bis(4-hydroxyphenyl)dimethylmethane, a phenol-formaldehyde
resin, or a resorcin-formaldehyde resin and a
halogen-containing epoxide as described above; and
polyepoxide compounds prepared by oxidizing an unsaturated
compound with peracetic acid, hydrogen peroxide, or the like,
that is, 3,4-epoxycyclohexene epoxide,
3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexenecarboxylate,
bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, and the like
Among them, a reaction product between a polyalcohol and
epichlorohydrin, that is, a polyglycidyl ether compound of a
polyalcohol, develops excellent performance and thus is
particularly preferable.
[00661
In addition, it is also preferable that latexes and like
components are used with and contained in the pre-treatment
liquid used in the invention.
[00671
In addition, in the method of the invention, it is
preferable that the fiber cord is a fiber cord including a
twisted fiber. When the fiber cord is twisted, the
pre-treatment liquid penetrates into the fiber cord more
effectively. In addition, it is preferable that the
pre-treatment liquid also contains an epoxy compound in
addition tothe two kinds ofblockedpolyisocyanate compounds
When an epoxy compound is used together with the trio kinds of
blockedpolyisocyanatecompounds, theeffect oftheunblocking
temperature difference between the two kinds of blocked
isocyanate compounds is exerted more clearly.
[0068]
The blocked polyisocyanate compounds used in the
inventionhavehigh affinity forthe fiber-formingpolymer and
have excellent penetration and cohesive strength. Further,
in order to promote the adhesion to the fiber surface and the
polyisocyanate crosslinking reaction and obtain a firm
adhesive film, it is preferable to use an epoxy compound
together. Further, inthe casewhere anepoxy compoundis used
together with the pre-treatment liquid of the invention like
this, it is preferable that the epoxy compound is used such
that the solids weight ratio of epoxy compound/blocked
polyisocyanate compounds is 5/95 to 30/70, more preferably
10/90 to 25/75, particularly 15/85 to 25/75.
[0069]
In the case where an epoxy compound is used together,
in the stage where water is distilled from the attached fiber
and a heat treatment is performed, the epoxy compound and the
blocked polyisocyanate compounds are thermally diffused into
the fiber cord over a sufficient period of time, and then the
two kinds of blocking agents are released, causing a
crosslinking reaction. As a result, high interface
reinforceability is obtained. At the time of this thermal
diffusion, it is preferable that the epoxy compound and the
blocked polyisocyanate compounds are low-molecular-weight
components having high reaction activity. Accordingly, it is
preferable that the pre-treatment liquid doesnot contain a
hydroxyl group or alkali component which crosslinks the epoxy
compound or blocked polyisocyanate compounds or deactivates
them with water
[0070]
Here, with respect t o the s o l i d s weight r a t i o of epoxy
compound/blocked polyisocyanate compounds, i n the case where
the compositional proportion of epoxy i s too low, the curing
reaction r a t e of the isocyanate compounds tends t o decrease.
Thus, a firm crosslinked film is l e s s l i k e l y t o be obtained,
and the fraying r e s i s t a n c e is l e s s l i k e l y t o be improved.
Meanwhile, i n the case where the compositional proportion of
the epoxy compound is excessive, the crosslinked film tends
t o be hard and b r i t t l e . Accordingly, the bending f a t i g u e
r e s i s t a n c e and d u r a b i l i t y are l e s s l i k e l y t o be improved.
[0071]
In the invention, i n the case where the above epoxy
compound and blocked isocyanate compounds are used together,
it is preferable t h a t the pre-treatment l i q u i d ( f i r s t adhesive
treatment agent) is a water dispersion. S p e c i f i c a l l y , it is
preferabletouseawaterdispersioncontainingthematasolids
concentration of 2 t o 20 w t % , more preferably 5 t o 15 w t % , a t
the time of a p p l i c a t i o n t o t h e f i b e r .
[0072]
In the method of the invention, f o r the a p p l i c a t i o n of
such a water dispersion (pre-treatment l i q u i d ) t o the f i b e r ,
it is possible t o employ techniques such as contact with a
r o l l e r , a p p l i c a t i o n by spraying from a nozzle, or immersion
i n a s o l u t i o n . I n a d d i t i o n , it is preferable t h a t the amount
of solids of the pre-treatment liquid attached to the fiber
is within a range of 0.5 to 5.0 wt%. When the amount attached
is too small, the filaments forming the fiber cord cannot be
sufficiently bundled, resulting in a decrease in fraying
resistance. In particular, in the case where the fiber cord
for reinforcement of the invention is used as a belt core
material, it tends to be difficult to obtain a sufficient and
uniform-.pre-treatment liquid film for protecting the fiber
interface from rubber vulcanization at the time of shaping a
belt or aminolysis at the time of using the belt. Meanwhile,
in the case where the amount attached is too large, there is
atendencythatgumrning-upor thelike occurs in the subsequent
adhesive treatment step or shaping step, resulting in a
decrease in process passing properties. Therefore, it is
preferable that the amount of solids of the pre-treatment
liquid attached to the fiber is 0.5 to 5.0 wt%, still more
preferably 1.0 to 3.0 wt%. The amount of solids attached can
be controlled by techniques such as squeezing with a
pressure-welding roller, scraping off with a scraper or the
like, blowing off by air blorqing, suction, or a beater. In
order to increase the amount attached, attachment may be
performed several times.
[00731
In themethodofthe invention, the pre-treatment liquid
is applied to the fiber cord, followed by a heat treatment.
Here, as preferred heat treatment conditions, two-stage
heating is preferable. S p e c i f i c a l l y , f o r example, it is
p r e f e r a b l e t h a t drying is performed a t a temperature of 80 t o
150°C f o r 60 t o 120 seconds, and then a heat treatment is
performedatatemperature o f 1 8 0 t o 240°C for 60to180 seconds.
roo741
That IS, f i r s t , through the f i r s t - s t a g e heat treatment,
moisture on the cord surface and inside the cord is d i s t i l l e d
o f f , and the pre-treatment l i q u i d containing blocked
poly~socyanatecompoundsa rethermallydiffusedintothe f l b e r
cord a t the same time. In the case where the treatment
condition is such t h a t the temperature is low or the time is
s h o r t , moisture tends t o remain n o t - d i s t i l l e d o f f .
Accordingly, there is a t e n d e n c y t h a t t h e isocyanate compounds
- andthelikearedeactivatedinthesubsequenthigh-temperature
heat treatment, making it impossible t o obtain a f i r m
c r o s s l i n k e d f i l m . On the other hand, i n the case where the
f i r s t - s t a g e heat treatment is a high-temperature treatment,
the c r o s s l i n k i n g r e a c t i o n of the isocyanate compounds and the
l i k e t a k e s p l a c e as a competing reaction with hydrolysis, and
thus the f i l m t e n d s t o b e b r i t t l e . Further, there i s atendency
t h a t the remainingmoistureinthe f i b e r cordundergoes bumping,
whereby the penetration of the pre-treatment l i q u i d (first
adhesive treatment agent) i n t o the f i b e r cord is i n h i b i t e d .
In a d d i t i o n , i n t h e casewhere the heat treatment time is long,
t h e r e is a tendency t h a t the isocyanate compounds a r e
air-oxidized, and t h e film performance decreases. As the
conditions for the f i r s t - s t a g e heat treatment, it is more
p r e f e r a b l e t h a t t h e treatment is performed a t a temperature
of 90 t o 120°C for 60 t o 120 seconds.
[0075]
It is preferable t h a t following t h i s f i r s t - s t a g e heat
treatment (drying heat t r e a t m e n t ) , a second-stage heat
treatment is performed a t a temperature of 180 t o 24OoC f o r
60to180seconds. A s a r e s u l t , thecrosslinkingreactiontakes
place i n the s t a t e where moisture has been s u ' f f i c i e n t l y
d i s t i l l e d from the f i b e r cord and the blocked polyisocyanate
compounds and the l i k e have uniformlypermeatedinto the f i b e r
cord. In t h e case of a low-temperature treatment or a
short-time treatment, there is a t e n d e n c y t h a t t h e c r o s s l i n k i n g
reactiondoesnotsufficientlyprogress, andthe f i l m i s l i k e l y
t o be b r i t t l e . On t h e other hand, in the case of a
high-temperature treatment or a long-time treatment, t h e r e is
a tendency t h a t the isocyanate compounds and the l i k e are
pyrolyzed or air-oxidized, making it d i f f i c u l t t o exert the
performance. As the conditions for the second-stage heat
treatment, it is more p r e f e r a b l e t h a t the treatment is
performedatatemperature o f 2 0 0 t o 235OC for 6 0 t o l 2 0 seconds.
[00761
,In the method for producing a f i b e r cord f o r
reinforcement of the invention, as described above, a
pre-treatment liquid (first adhesive treatment agent) is
attachedtothe fiber cord, then the fiber cordhaving attached
thereto the pre-treatment liquid is once heat-treated, and
subsequentlyanadhesivetreatmentliquidis attachedthereto,
followed by a drying treatment.
LO0771
Here, the adhesive treatment liquid is to be suitably
changed according to the matrlx for which the fiber cord for
reinforcement of the invention is used. For example, in the /
case where the fiber cord is used for a rubber structure such
as a belt, ~t is preferable to use a resorcin-formalin-latex
(RFL) -ba.sed adhesive as the adhesive treatment liquid (second
adhesive treatment agent).
[0078]
This RFL-based adhesive has the above composition.
of 1 / 0 . 6 to 1/8 are preferably used, and various latexes are
usable.
[0079] .
In addition, it is also preferable that a crosslinking
agent is used together with this resorcin-formalin-latex
(RFL) -based adhesive treatment agent to serve as a treatment
agent, and examples thereof include amines, ethylene urea, and
blocked polyisocyanate compounds. Among them, considering
thetemporalstabilityofthetreatmentagent, the i n t e r a c t i o n
with the pre-treatment agent, and the l i k e , it is p r e f e r a b l e
t o use a blocked polyisocyanate compound. It is p r e f e r a b l e
t h a t the proportion of the c r o s s l i n k i n g agent added is within
a range of 0 . 5 t o 40 w t % r e l a t i v e t o the RFL component. This
is because although an increase i n the amount added usually
improves the adhesion s t r e n g t h , when the amount added is too
l a r g e , conversely, there is a tendency t h a t the compatibility
o f t h e adhesivewith rubbers decreases, r e s u l t i n g i n a d e c r e a s e
in adhesion strength t o rubbers.
[0080]
In the invention, it is p r e f e r a b l e t h a t an adhesive
l i q u i d (secondadhesive treatment agent) i s u s e d a s a t r e a t m e n t
liquidcomposedofawaterdispersion, a n d t h a t t h e t o t a l s o l i d s
concentr'ation of the water dispersion 1s within a range of 5
t o 30 w t % . In the case where the t o t a l s o l i d s concentration
of the treatment l i q u i d is lower than the above range, the
surface tension of the adhesive increases, and t h e adhesion
t o the f i b e r surface becomes l e s s uniform. A t the same time,
with a decrease i n the amount of s o l i d s attached, the adhesion
tends to decrease. On the other hand, i n the case where the
t o t a l s o l i d s concentration is higher than the above range, t h e
v i s c o s i t y of the treatment agent increases. Thus, there is
atendencythattheamountof s o l i d s attachedbecomestoolarge,
r e s u l t i n g i n a decrease i n process passing properties, such
as gumming-up in the adhesive treatment step or shaping step.
*
[0081]
In order to attach the adhesive treatment liquid (second
adhesivetreatment agent) tothe fiber likethis, it is possible
toemploytechniques suchas contact wit ha roller, application
by spraying from a nozzle, or immersion in a solution. In
addition, it is preferable that the amount of solids attached
to the fiber cord is within a range of 1.0 to 10.0 wt%, still
more preferably within a range of 1.5 to 8.0 wt%. The amount
of solids attached to the fiber cord can be controlled,
similarly to the above, by techniques such as squeezing with
a pressure-welding roller, scraping off with a scraper or the
like, blowing off by air blowing, suction, or a beater. In
order to increase the amount attached, attachment may be
performed several times.
roo821
In the method of the invention, the adhesive treatment
liquid is attached to the fiber cord and dried. As the heat
treatment conditions for drying, it is preferable that the
drying heat treatment is performed in two or more stages at
a temperature of 100°C to 250°C for 60 to 240 seconds. It is
. morepreferablethatdryingisperformedinatemperaturerange
of 120 to 180°C for 60 to 180 seconds, and then a heat treatment
is performed at a temperature of 200 to 245°C for 60 to 180
seconds. W h e n t h i s d r y i n g / h e a t t r e a t m e n t t e m p e r a t u r e s a r e t o o
low, t h e adhesion t o rubbers tends t o be i n s u f f i c i e n t , while
r.rhenthedrying/heattreatmenttemperatures are toohigh, t h e r e
is tendency t h a t the a i r oxidation of the adhesive components
a t high temperatures is promoted, r e s u l t i n g i n a decrease i n
adhesion a c t i v i t y .
[0083]
In the method for producing a f i b e r cord f o r
reinforcement of the invention, unlxke the conventional
solvent treatments, the organic-solvent-based adhesive
t r e a t m e n t f o r m u l a t i o n u s i n g a n i s o c y a n a t e compoundhaving f r e e
isocyanate groups is not employed. Accordingly, t h i s
production method is s a f e f o r the working environment and has
a reduced environmental impact. Then, a pre-treatment l i q u i d
t h a t e a s i l y penetrates i n t o t h e f i b e r cord is applied
preferably as awater-basedadhesivetreatmentagent, t h a t is,
a water dispersion, and two kinds of blocked polyisocyanate
compounds a r e successivelyunblocked, thereby causing a curing
reaction while suppressing d e a c t i v a t i o n , whereby a firm,
f l e x i b l e crosslinked film i s formed. The invention enhances
t h e i n t e r f a c e a d h e s i o n s t r e n g t h b e t w e e n t h e f i b e r s u r f a c e layer
and the f i b e r inner layer impregnated with the pre-treatment
l i q u i d ( f i r s t adhesive treatment agent l a y e r ) , as well as
between t h e f i b e r inner layer ( f i r s t adhesive treatment agent
layer) and the adhesive layer (second adhesive treatment agent
l a y e r ) . As a r e s u l t , it has become possible t o achieve
improvements in both fraylng resistance and bending fatigue
resistance, while ensuring high adhesion.
[Examples 1
[00841
Hereinafter, the invention will be described with
reference to examples. However, these examples are provided
by way of illustration and do not llmit the invention.
Incidentally, evaluationsinthe examples ofthe inventionwere
made according to the following measurement methods.
100851
(1) Measurement of Compound Proportions in Fiber Cord Inner
Layer Part (Pyrolysis GC-MS)
From an obtained fiber cord for reinforcement, the
adhesive layer (outermost layer part) was peeled off to give
a fiber cord having fibers exposed to the surface. Further,
the outside quarter of the fiber cord was trimmed off. From
the inner layer part whose diameter is 75% ofthe original fiber
cord diameter, a measurement sample weighing 5 mg was
collected.
[0086] .
Using this sample, the compound proportions (weight
ratio) were determined from the peak areas of the compound A1
and the compound B1 by a cut & weight method using a pyrolyzer
(manufactured by Japan Analytical Industry Co., Ltd., Curie
Point Pyrolyzer "CCP JHP-5") and a gas chromatograph mass
spectrometer (manufacturedby Shimadzu C o r p o r a t i o n C o . , L t d . ,
"GC-MS QP2010") .
[0087]
(Measurement Conditions)
CCP (Pyrolyzer)
Oven temperature; 250°C, Needle temperature; 250°C,
Sample heating; 590°C x 15 sec
GC (Gas Chromatograph)
Vaporizing chamber temperature; 250°C, Column; DB-5ms,
S p l i t r a t i o ; 1/100,
Columnopenprogram; 60°C x 2min, h e a t e d a t a t e m p e r a t u r e
rise r a t e of 10°C/min t o 180°C o r 320°C.
MS (Mass Spectrometer)
Ion source temperature; 200°C, I n t e r f a c e temperature;
250°C, Mass range; 29 t o 600
[00881
(2) Unblocking Temperature of Blocked Polyisocyanate
Using a thermobalance (TG/DTA, manufactured by Rigaku
I n t e r n a t i o n a l Corporation, "TAS-200"), 10 mg of a blocked
p o l y i s o c y a n a t e , from+rhichwaterhadbeendistilled, was heated
i n a n i t r b g e n a t m o s p h e r e fromroomtemperature a t a t e m p e r a t u r e
rise r a t e of 10°C/min. The temperature at which t h e weight of
t h e sample was reduced by 10 + r t % was d e f i n e d as t h e unblocking
temperature.
[00891
(3) T e n s i l e S t r e n g t h , Breaking Elongation, 150-N Load
Elongation ( I n t e r m e d i a t e E l o n g a t i o n ) , and 150°C Dry H e a t
Shrinkage of Cord
Each was determined by measurement i n accordance with
J I S L1017.
[00901
( 4 ) Cord Hardness
Measurement w a s p e r f o r m e d u s i n g a G u r l e y h a r d n e s s t e s t e r
(manufactured by T e s t e r Sangyo Co., Ltd. ) i n accordance with
J I S 21096-6.20.
[00911
(5) Peel Adhesion of Cord
This showsthe peeladhesionbetweenanadhesive-treated
f i b e r cord and a rubber. Seven cords tiere embedded i n t h e
s u r f a c e l a y e r o f a sulfur-basedEPDMrubberunvulcanizedsheet,
followed by v u l c a n i z a t i o n a t a t e m p e r a t u r e o f 150°C f o r 30
minutes under a p r e s s i n g p r e s s u r e of 90 kg/cmz. Next, every
o t h e r one of t h e cords from both ends, f o u r cords i n t o t a l ,
wereremoved, andtheremainingthreecordswere simultaneously
p e e l e d f r o m t h e r u b b e r s h e e t a t a r a t e o f 2 0 0 m m / m i n . The f o r c e s
r e q u i r e d f o r . p e e l i n g (N/3 cords) w e r e averaged t o determine
t h e p e e l adhesion per cord (N/cord).
[00921
(6) Bending F a t i g u e R e s i s t a n c e and Fraying Resistance of Cord
Eight adhesive-treated f i b e r cords were embedded a t
regular i n t e r v a l s i n two unvulcanized rubber sheets of
sulfur-based EPDM rubber (50 mm in width, 500 mm i n length,
and 2 rnm i n t h i c k n e s s ) , followed by vulcanization a t a
temperatpre of 15OoC f o r 30 minutes under a pressing pressure
o f 5 0 kg/cm2, therebygiving abelt-like rubber s h a p e d a r t i c l e .
Next, while applying a load of 30 kg, the b e l t - l i k e rubber
shaped a r t i c l e was i n s t a l l e d on a r o l l e r 20 mm i n diameter,
and subjected t o back-and-forth movements a t 100 rpm i n an
atmosphere a t 100°C f o r a r o l l e r bending ( c o n t a c t ) distance
of 100 mm. After repeating bending 10,000 times, t h e cords
were taken out, and the remaining strength was measured to
determine the s t r e n g t h r e t e n t i o n a f t e r bending f a t i g u e . In
addition, a f t e r the bending fatigue, the b e l t - l i k e rubber
shaped body was cut i n the d i r e c t i o n perpendicular t o the
embedded f i b e r cords, and the bundling conditions o f t h e f i b e r
cords exposedto the cross-section were observed v i s u a l l y and
a l s o u n d e r a n o p t i c a l m i c r o s c o p e t o e v a l u a t e f r a y i n g r e s i s t a n c e .
The f r a y i n g r e s i s t a n c e was r a t e d i n t h e f o l l o w i n g t h r e e g r a d e s .
[0093]
[Fraying Resistance ( a f t e r Bending Fatigue T e s t ) ]
5: The filaments of t h e f i b e r cords are bundled, and no
abnormalities a r e seen i n the appearance; e x c e l l e n t . 3:
Some filaments of the f i b e r cords have s l i g h t bundling
f a i l u r e s ; however, good.
1: The filaments of t h e f i b e r cords have bundling
f a i l u r e s and are not bundled.
[0094]
[Example 1 1
To 22.8 g of a polyepoxide compound having a s o r b i t o l
polyglycidyl e t h e r s t r u c t u r e ("Denacol EX-614B" manufactured
by Nagase ChemteX Corporation; concentration: 100%) was added
8.8 g o f anaqueous d i a l k y l s u l f o s u c c i n a t e s o d i u m s a l t s o l u t i o n
("Neocol SW-C" manufactured by DKS Co., Ltd. ; concentration:
70%) as a s u r f a c t a n t , followed by s t i r r i n g , and the mixture
wasaddedto723.7 g o f r . ~ a t e r w i t h s t i r r i n g a n d d i s s o l v e d . Then,
226.5 g of a dimethylpyrazole block-HDI trimmer condensate
having three or more functional groups ("Trixene 327"
manufacturedby Baxenden ( u K ) ; unblockingtemperature: 115OC,
concentration: 38%) as a blocked polyisocyanate compound A2
(shows as "a" i n Table 1) and 18.2 g of a b i f u n c t i o n a l
E-caprolactam-blocked diphenylmethane diisocyanate
("GRILBOND IL-6"manufacturedby EMS; unblockingtemperature:
170°C, concentration: 50%) as a blocked polyisocyanate
compound Bz (shown as "b" i n Table 1) were added t h e r e t o with
s t i r r i n g , thereby preparing a pre-treatment l i q u i d (water
dispersion of a f i r s t adhesive treatment agent, s o l i d s
concentration: 1 2 % ) , wherein t h e s o l i d s weight r a t i o of epoxy
compound/blocked polyisocyanate compounds (the t o t a l of the
blocked polyisocyanate compound A2 and the blocked
polyisocyanate compound B2) was 20/80, and the solids weight
ratio of blocked p~l~isoc'yanate compound' A2/blocked
polyisocyanate compound B2 was 90/10
19.8 g of a resorcin-formalin initial condensate having
a resorcin/formalin ( R / F ) molar ratio of 1/0.6 ("Sumikanol
7005" manufactured by Sumitomo Chemical Co., Ltd.;
concentration: 65%) wasdissolvedinanaqueousalkalisolution
prepared by adding 5.0 g of 10% caustic soda and 19.9 g of 20%
ammonia water to 154.5 g of water, and then 138.3 g of a
vinylpyridine-styrene-butadiene latex ("Pyratex"
manufactured by Nippon A&L Inc.; concentration: 41%), 206.2
g of a polybutadiene latex ("Nippol LX1llNFf' manufactured by
Zeon Corporation; concentration: 55%), and 363.6 g of water
were added thereto. 16.8 g of 37% formalin water and 75.9 g
o f a methylethylketoxime-blocked diphenylmethane
diisocyanate ("DM6400M manufacturedby Meisei Chemical Works,
Ltd.; concentration: 40%) were addedtothis mixture, followed
by aging at 20°C for 48 hours, thereby preparing an adhesive
treatment liquid having a solids concentration of 22%
(RFL-based second adhesive treatment agent for second
treatment bath) .
[00961
Twopolyethyleneterephthalateuntreatedfibersof1,100
dtex/192 fil ("P904Br' manufactured by Teijin Fibers) were
first-twisted in the S-direction (number of twists: 220/m),
and then three of the first-twisted cords were second-twisted
in the Z-direction (number of twists: 120/m), thereby giving
a polyester fiber cord. Using Computreater (dip cord treater
manufactured by C.A. Litzler), this fiber cord was fed at a
rateof22m/minandirnmersedinthepre-treatmentliquid (first
adhesivetreatment agent), thendriedata fixedlengthat120°C
for 60 seconds, and heat-treated at a fixed length at 235OC
for 60 seconds. Subsequently, the cord was immersed in the
adhesive treatment liquid (second treatment bath), then dried
at a fixed length at 160°C for 120 seconds, and heat-treated
under 3.5% stretching conditions at 230°C for 150 seconds,
thereby. giving a polyester (polyethylene terephthalate)
adhesive-treated fiber cord. This adhesive-treated fiber
cordhadattachedtheretothepre-treatment liquid (first-bath
adhesive treatment agent) and adhesive treatment liquid
(second-bath adhesive treatment agent) in amounts of 2.6 vrt%
and 4.8 bit%, respectively, relative to the weight of the
..polyester fiber cord on a solids basis.
[0097]
The compound proportions' in the inner layer part of the
obtained fiber cord were measured (pyrolysis GC-MS). As a
result, the ratio of the compound Al derived from
dimethylpyrazole (DMP) and the compound Bi derived from
&-caprolactam were as follows: Ai/Bi = 80/20. The performance
evaluation results ofthe obtained fiber cordare collectively
shown in Table 1.
[0098]
[Examples 2, 3, and 4, Comparative Example 11
Polyester fiber cords were subjected to an adhesive
treatment in the same manner as in Example 1, except that the
solids weight ratio of blocked polyisocyanate compound
A2/blocked polyisocyanate compound B2 in the pre-treatment
liquid (first adhesive treatment agent) of 90/10 in Example
1 was changed as shown in Table 1 in preparation. The
performance evaluation results of the obtained polyester
adhesive-treated fiber cords are collectively shown in Table
[Comparative Example 21
A pol.yester fiber cord was subjected to an adhesive
treatment in the same manner as in Example 1, except that in
the pre-treatment liquid (first adhesive treatment agent),
only the blocked polyisocyanate compound A2 was used, and the
blocked polyisocyanate compound B2 was not used. The
performance evaluation results of the obtained polyester
adhesive-treated fiber cord are collectively shown in Table
[OlOO]
[Table 11
Pre-Treatment Liquid
Physical Properties of
Fiber Cord for
Reinforcement
a; Dimethylpyrazole block-HDI trimmer condensate
b; c-Caprolactam-blocked diphenylmethane diisocyanate
[0101]
[Examples 5, 6, and 71
Polyester f i b e r cords were subjected to an adhesive
treatment in the same manner as i n Example I, except t h a t the
s o l i d s weight r a t i o of epoxy compound/blocked polyisocyanate
compounds ( t o t a l amount) i n the pre-treatment l i q u i d ( f i r s t
adhesive treatment agent) of 20/80 i n Example 1 was changed
as s h o ~ i n i n T a b l e 2 i n p r e p a r a t i o n . Theperformance evaluation
r e s u l t s o f t h e obtainedpolyesteradhesive-treatedfibercords
a r e c o l l e c t i v e l y shown in Table 2 .
[0102]
[Example 81
A polyester f i b e r cord was subjected t o an adhesive
treatment i n the same manner as i n Example 1, except t h a t i n
thepre-treatment liquid ( f i r s t adhesive treatment a g e n t ) , the
blocked polyisocyanate compound A2 was changed from the
dimethylpyrazoleblock-HDI trimmer condensate usedin Example
1 to a d i e t h y l malonate-HDI trimmer condensate having three
or more functional groups (unblocking temperature: 120°C,
concentration: 25%) (shown as "a'" in Table 2 ) . The
performance evaluation r e s u l t s of the obtained polyester
adhesive-treated f i b e r cord are c o l l e c t i v e l y shown in Table
2 .
[0103]
[Example 91
A polyester fiber cord tias subjected to an.adhesive
treatment in the same manner as in Example 1, except that in
the adhesive treatment liquid (RFL-based second adhesive
treatment agent for second treatment bath), 138.3 g of VpSBR
(concentration: 41%) in the vinylpyridine-styrene-butadiene
latex (VpSBR) and polybutadiene latex (PB) in Example 1 was
replacedbrith 127.5 gof a chlorosulfonatedpolyethylene (CSM)
latex (Sepolex CSM, manufactured by Sumitomo Seika Chemicals
Co., Ltd.; concentration: 40%) (Ll) . The performance
evaluation results ofthe obtainedpolyester adhesive-treated
fiber cord are collectively shown in Table 2.
[0104]
[Table 21
1 1 Examole 1 1 Examole 5 1 ~xamale6 1 Examole 7 1 Examole 8 Exarnole 9 1
1
0Ep~~yl(Az+BzR)a tio 20180 10190 20180 20180 1
Pre-Treatment Liquid
1 Adhesive Treatment I :-,.:A 1 Latex Component
Compound A2
/ VpIBP 1 VplBP 1 VplBP 1 VpIBP 1 VplBP 1 CSMIBP 1
Compound B2
Physical Properties of
I ! Peel Adhesion iNlcord) I 29.4 I 28.3 I 26.0 ! 26.4 I 27.9 I 29.2 I
a
Strength Reteniion after Bending
Fatigue (%)
94 93 96 80 92 95
I
b
/ Fravina Resistance 1 5 1 5 1 5 I 5 I 5 1 5 1
a
,47187 Ratio
a; Dimethylpyrazole biock-HDI trimmer condensate
a'; Diethyl malonate-HDI trimmer condensate
b; E-Caprolactam-biocked diphenylmethane diisocyanate
Vp; VpSBR latex
CSM; CSM latex
BP; BP latex
b
a
90110
b
a
90110
b
a'
9011 0
a
b b
9011 0 90110 9011 0
[OlOS]
In Examples 1 to 9 of the invention, as compared with
comparativeexamples, the cords hadhighhardness andexcellent
bending fatigue resistance, and the fraying resistance after
bending fatigue bias also excellent. In addition, in the
examples, the cord strength and breaking elongationtendedto
be lower as compared with the comparative examples havi.ng poor
bundling properties; this is considered to be the influence
of an increase in bundling properties caused by the formation
o f a firm film due to the penetration of the pre-treatment
liquid (first adhesive treatment agent) into the fiber cord.
However, the strength retention after bending fatigue of each
fiber cord is hi.gh, and also the modulus (intermediate.
elongation) and dry heat shrinkage, i~~hicahr e important as' a
belt cord, are maintained at values indicating sufficient
performance.
[O106]
However, in the case where the proportion of, among the
blocked isocyanate compounds in the pre-treatment liquid, the
rigid high-temperature-dissociation blocked isocyanate
compound i32 is high as in Example 4, or in the case where the
proportion of the epoxy compound in the pre-treatment liquid
is high as in Example 7, there is a tendency that the adhesi-on
film is slightly weak, resulting in slight decreases in cord
hardness, fraying resistance, and adhesion.
In addition, in Comparative Example 1, only a
bifunctional high-temperature-dissociation diisocyanate
compound BZ was used as a blocked isocyanate compound. As a
result, the cord hardness, fraying resistance, adhesion, and
bending fatigue resistance were all lower as compared * with the
, ,
examples .. >
Industrial Applicability
[ O l O O ]
According to the invention, a fiber cord for
reinforcement having significantly improved fraying
resistance andbeing excellent in adhesion to rubbers, bending
fatigue resistance, anddurabilityis obtained. Inparticular,
the fibqr cord for reinforcement of the invention is suitable
for rubber reinforcement, particularly as atransmission belt
cord. The fiber cordisparticularlyoptimalforautomobiles,
- herewe weight reduction is required. Inaddition, inthemethod
of the invention, water-based adhesive treatments can also be
employed. Thus, as an environment-conscious method for
producing an adhesive-treated fiber cord, the method can be
significantly effective in reducing the environmental impact
and cost.
[Claim 11
A fiber cord for reinforcement, comprising an adhesive
treatment agent attached to a surface thereof, characterized
inthat the fiber cordincludes, in an inner layerpart thereof,
a compound A1 having a molecular weight of less than 1,000 and
a smaller amount OF a compound El than the compound Al, the
compoundA~beinganaromaticcornpoundorac ompoundcontaining
an a-dicarboxylic acid component, the compound El being an
aliphatic compound or an alicyclic compound.
[Claim 21
The fiber cord for reinforcement according to claim 1,
wherein the adhesive treatment agent is a
resorciri-formalin-latex (RFL)-based adhesive.
[Claim 31
The fiber cord for reinforcement according to claim 1
or 2, wherein the fiber cord includes a. twisted multifilament
. '
fiber.
[Claim 4'1
The fiber cord for reinforcement according to any one
of claims 1 to 3, wherein the fiber cord includes a synthetic
fiber .
[Claim 51
The fiber cord for reinforcement according to any one
of claims 1 to 4, wherein the aromatic compound is a
heterocyclic compound.
[Claim 61
The fiber cord tor reinforcement according to any one
of claims 1 to 5, wherein the cornpound ill is located only in
,the inner layer part of the fiber cord.
[Claim 71
The fiber cord for reinforcement according to any one
of claims 1 to 6, wherein a compound having a hexamethylene
diisocyanate (HDI) trimer structure is present in the inner
layer part of the fiber cord.
[Claim D l
The fiber cord for reinforcement according to any one
of claims 1to 7, whereinno latex is present in the inner layer
part of the fiber cord.
[Claim 91
A method for producing a fiber cord for reinforcement,
including treating a fiber cord in two stages with a
pre-treatment liquid and an adhesive treatment liquid,
the method being characterized in that
the pre-treatment liquid contains two kinds of blocked
isocyanate compounds t h a t a r e a c o m p o ~ n d A ~ a n d a s m a l l e r a m o u n t
of a compound B2, the compound A2 having an isocyanate group
blocked trith an aromatic compound or a compound containing an
a-dicarboxylic acid component, the compound B2 having an
isocyanate group blocked with an aliphatic compound or an
alicyclic compound, and
a fiber cord having the pre-treatment liquid attached
thereto is once subjected to a heat treatment, and then the
adhesive treatment liquid is attached thereto, follovred by a
drying treatment.
[Claim 101
The method for producing a fiber cord for reinforcement
according to claim 9, wherein the aromatic compound is a
heterocyclic compound.
[Claim 111
The method for producing a fiber cord for reinforcement
accordi.ng to claim 9 or 10, wherein the unblocking temperature
, of the compound A2 is lower than the unblocking temperature
of the compound Bz.
[Claim 1-21 ..:
The method f o r producj ny a f i b e r cord for reinforcement
accordin-g t o any one of claims 9 t o 11, wherein the compound
AZ has a hexamethylene dijsocyanate (HDI) trimer s t r u c t u r e .
. [Clairn 131
The method f o r producing a f i b e r cord f o r reinforceme~lt
according t o any one of claims 9 t o 12, wherein the cornpounil
Ei has an isocyanate group blocked with an a l i p h a t i c compound
or an a l i c y c l i c compound.