TECHNICAL FIELD
The present invention relates to a power transmission belt such as V-belt etnd Vribbed
belt, and more specifically, relartes to apower tmusdssion belt excellent in the
durability perfiommce and tmmmhiaa &eieacy.
BACKGROUND ART
Conventiodl~in order to enhance the lateral pmmm mistance of a pow
transmission belt such as V-belt and Vwribbed belt, a short fiber is blended as a ~ebforcing
agent in a compression rubbar layer. For example, Patent Doment 1 $isclases s rubber
V-belt which is a belt comprising ap elastic adhesive layer bavling a cod embedded therein
and an elastic holding layer (compression rubber layer) locatsd on upper axld l o w sides of
the elastic adhesive layer, in which the eWc holding layer contains c h l o m p rubber, a
reinforcing filler, a metal oxide v u l a n g agent, b i d e b i d e and an mamid short fiber
and the mamid short fiber is oriented in the width direction of the belt. In this documat,
the elastic modulus h the grain direction (short fiber odenbtion dhction) is hxwIsd by
the orientalion of the d d fik to thereby maintain the lateral resistance and
improve the durability.
Patent Document 2 discloses a cogged V-belt having a compssion r u b k layer
and an extensible rubber layer and having a core wire embedded kein along tbe
fongitudiial direction, in which the rubber hmhess (JIS-A) of the extensible m b k layer
is Erom 85 to 92, the rubber hardness (JIS-A) of the compression rubber layer is h m 90 to
98, and the rubk hardness of the compression rubber layer is set higher by 3 to 10 or
more (JS-A} tban the Nbber hardness dthe atedble rubber layer; and describes
incorporating carbon black and an ananid short fiber into the extensible mbbei layer d
the compression rubber layer,
Patent Document 3 discloses a power traasmission V-belt where the rubber
hardness of at least either one of extensbIe and compression rubber layers is set to be from
90 to 9d0and the r u b k hardness of an adhesive rubber layer is set to be fiorn 83 to 8g0,
respectively, and an aramid short fiber is oriented in the belt width direction in the
extensible and cornpion rubber layers. In this document, early generation of cracking
ox separation (delamination) of each mhh layer and a cord are prevented, whereby the
lateral pressure resistance is improved and in tum, the high-load power translniseion
capacity is enhanced.
Meanwhile, in recent y m , it is required of the power trammission belt ta reduoe
power transmission loss of the belt and duma the fuel sraving perfamanee so as to
improve the fuel cansumption efficiency, as well as the above-mentioxled the l a W
pressure resistance and durability. For example, in paragraph [0005] of Patent X)bcu~16nt
3, it is indicated that when the rubber hardness of the belt is raised, the flexural rigidity
becomes high and with a small pulley diameter, power txanstllissian loss occm.
Therefore, attempts are made to pmvide a cog on the b e r cir-a1 side or on both
the inner circumfermtid side and the outer eiroderendal side (back surfbe side) of a VbeIt
so as to reduce the flexural rigidity of the belt and *by suppress the power
transmission loss, As this kind of belt, a cogged V-belt is gemrally known.
With respect to the improvement of lateral pressure mistance and durability, as
described in Patent Docwnents 1 to 3, it is an efkdive measure to increase the amount of a
high-modulus short fiber such as aramid fiber or a rehfkcing egent such as carboo bIack
and thereby raise the rubber hardness, H o w , what the: rubber hardness is raised, this
leads to an increase in the flexural rigidity of the &I$ as as reresult, the bending fbtigue is
detdorated or with a d pulley diameter, fhe power ~ s s i olonss o f the belt is
increased to deteriorate the fuel saving pdu-ee. On the ofher ham& when the rubber
hardness is lowered so as to improve the bending Mgue and l e l saving performance, the
lateral pressure rmis~anceis reduced and the belt life may expire early. Tbat is, a series of
characteristics of lateral p r m resistance and durability are in a tmboff relationship
with a series of characteristics of bending fatigue and fuel saving pdo-e. In this
connection, the bending fatigue and &I saving perf~mmcces rn be improved by providing
a cog on the inner c i d n t i a l side or bath the inner c i r c d d a l side and the outer
circumferentid side of a V-belt, but since the rubber strength is raised so as to maintainthe
Iateral pressure resistance and durabilitys the f k l saving performance is not yet satisfied at
present. Accordingly, a preferred rubber.composition (particularly, a rubber cornpodtion
of the compression rubber layer) is demanded,
Incidentally, tbis kind of V-belt inc1h a variable speed belt used far a
continuously variable transmission. In this variable speed belt, the belt moves up and
down (or back and force) in thE pulley radial dktion an the pulley so as to change the
gear ratio (rotation ratio between a drive pulley and a driven pulley). If this movement is
not smoothly effected, the &ear force h m the pulley strongly acts to cause separation
between the mbber layers (adhesive rubber layer aad tmmpessian mbber layer) or betwan
the adhesive rubber layer and the core win, and the fuel saving p d i(nat onZy fbel
saving performance attributable to fl muid rigidity but also fuel saving pufmance based
an reduction in the slid'mg property) deteriorates. In this connection, the fkiction
coefficient cas be reduced by blending a Iarge amount of a short fiber or a midorcing
agent such as carbon black to thereby raise the mbber hardness or by protruding a short
fiber firom the friction transmission sdam, but when 61 large mount of a reinfor* agent
is blended, the above-described pmblem arises.
WLATED ART DOCUMElVTS
PATENT LITERAPatent
Document 1 : JP-13-5-63656
Patent hament 2: JP-A-2009-150538
Patent Document 3: JP-A-101238596
SUMMARY OFTHE INVENTION
PROBLEMS TO BE SOLVED BY INVENTION
Accordingly, an object of the present invention is to provide a power tmsdsion
belt capable of reducing power ?mamission loss.
Another object of the. present invation is to provide a power transmission belt
capable of maintaining the l a d pressure resistance and dmbility and at the same h e ,
improving the bending fgtigue and h l saving p d o m (both flexural rigidity and
sliding property) even without excessively raising the tubber hardness.
MEANS FOR SOLVING THE PROBLEMS
As a result of intensive studies to attarin the above-described objects, the present
inventors have fomd that when a cornmion rubber layer of a power trdssion belt is
formed of a rubber com~sitionco ntaining a rubk component, a fm acid amide and a
short fiber, the fatty acid mide not only h c e s Xhe dkpersibility and orientation of the
short fiber but also improves the adherence of tbe rubber ccqxment to the short fiber and
the fatty acid amide blooms (precipitates) or bleeds-out ta the d i m e (fhe Ection
transmission sdace coming into contact with a pulley) of the compression rubber layer .to
reduce the fkictian coefficient on the rubber layer d a c e and enhnoe the pow=
transmission property (transmission efficiency), and thy a~~~rnpIitshhe dpr esent
invention.
That is, the power tmmmbio11 beit according ta the present invention comprises
an adhesive rubber layer having a care wire embedded therein in the 2..on.gitudhd direction
of the belt, a compression rubber layer fonned on one d a c e ofthe adhesive rubba layer,
and an extensible rubber Iayer farmed on mother swfke of said adhesive mbber layer.
In the power transmission belt having such a stmctme, at least the comp~giunru bber
Iayer contains a fatty acid amidc and a short fiber.
In such a power transmission belt, the fatty acid d d e acts as a dispersant for the
short fiber, so that the short fiber dispcrsibility and the short fiber m i d o n (in the
direction paraIlei to the belt width direction) in a rubber oomposition em be improved and
the lateral pressure resistance and wear resistance of the cumpressiori nzbba layer can be
enhanced. Also, thanks to the f'atty acid atnide, adbesivaess of the short fiber to a rubber
composition (mdhx rubber: a rubber composition excluding a short f i b ) dm the
compression rubber layer can be enhanced. In patidein the caw when an adhesiontreated
short fiber is used, the W i v e MU3nponent on the surface thereof (outer layer)
chemicaIIy interacts with the fm mid amide, whereby the adhemess of the short fiber
to a rubber composition (matrix rubber) constituting the cumpression rubber layer can be
raised. In turn, a compression rubber layer excellent in the modulus, tade strength and
tear strength can be formed. Furthemore, the frttty acid arnide acts as an internal
lubricant to reduce the modulus of the matrix rubber (or making flexibIe) but w h used in
combination with the short fiber, can pavent redudion of the modulus. That is, in the
case where a fatty acid amide and a short fiber are used in comb'ion, tbe ma&
component of the compdon mbkr layer can be d e flexible and at thq m e time, a
compression rubber layer excellent in the mechanical charactclisfics can be formed, so that
the bending fatigue and fuel saving perfsrmance of the belt rn be impmved without
raising the hardness of the compression rubber layer. In addition, the fatty acid amide
blooms (precipitates) or bleedsaut to the surfwe (the friction lnmsmissi~nd kcec onning
into contact with a pulley) of the compression rubber layer and acts as an extend lubricant
to reduce the Ectian coefficient on the rubber layer surliice and facilitaie the fiicti~n
between the rubber lay= &he and a pulIey, as a result, the durability and fuel saving
performance of the belt (particularly, the frtel saving performartoe ofa d & 1 e speed beit)
are enhanced. According1y, in the present invention, the chzmC%&~cosf h&rd pressure
resistance and durability and the characteristics of bending fbtigue and fuel savhg
performance can be satisfied at the. same time.
The fatty acid amide may contain at least one member selected bm a wturaEed or
unsaturated long-chain fatly acid d d e and a satmated or unsaturated long-chain fatty acid
ester amide. Also, the short fik preferably con- at least an adhesion-treated &cat
fiber, and the short fiber may contain at legst an aramid fiber. More qecEcally, the
rubber component of the compression rubber layer may contain c h l mru~bbe r, the
fatty acid mide may contain at least a saturated or unmtmtd &ty acid monoamide
having a carbon number of 10 to 26, and an adhesive component containing at Ieast an
initial condensate of mrcin and form;aIin and a latex may be a$ta&d b JIG short fiber
fe.g., at least to a pat of the periphery (outer layer or surface) of the short fiber).
Furthermore, an adhesive component coataining a styrenebutadierwuinylpyridine
terpolymer may be attached to the short fiber,
The amounts of the fw acid 6 d e and short fibex used can ba s e I d in the
range where the friction coefficient on the surfbe of the mprtssion rubber layer can be
appropriably reduced wUe enhancing the rnecbical dmwteristics of xhe lapet and at
the same time, the bending stress ean be reduced without excessively raising the han&tss
of the compression rubber layer, thereby making it possible to impmve the W i n g fdgue
and he1 saving perfiirmance. In the rubbet composition constituting the canpsion
rubber layer, the ratio of the fiitty acid amide may be, for ample, appro-iy from 0.5
to 10 parts by mass per 100 parts by mass of the raw mat&il rubber component, and the
ratia of the short fiber may be, for example, approximately hm 10 to 40 par'& by mass per
100 parts by mass of the r ~mlatt~ria l rubber compomt
The present invention incIudes a rubber composition for forming at least one
rubber layer selected b m a compressian rubber layer and an extensible mbk layer of a
power transmission belt, which the rubber composition c~~pxisae tsu bber component, a
fatty acid amide and a short fiber. In this cornposition, the short fiber pdka'ably contains
at least an adhesion-treated short fiber. The present invention &o includes a m W for
reducing power transmission loss (a d a dfo r enhancing a power ~ s s i oprnope rtg
or a transmission efficiency) by forming a compression rubber layer ofa power
transmission belt from the above-described rubber cumposition,
ADVANTAGE OF THE INVENTION
In the present invention, the cbmpression rubber layer contains a fatty acid amide
and a short fiber, so that the power transmission bss by the power transmission belt can be
reduced and the transmission 6ciency can be enhanced. Also, even without excessively
raising the rubber haniness, the lateral prsure resistance and durability can be mabtaiaed
and at the same h e , the bending Wgue and fuel saving perf- (both f l e d
rigidity and sliding property) can be hpraved. fn particular, the cdcting
characteristics, that is, the ch8~teristicos f lakral pressure resistanoe and durability and
the characteristics of bending fatigue and fuer saving perfamame, can be satisfied at the
same time,
BFUEF DESCRIPTION OF TBE DRAWINGS
[Fig. 11 Fig. 1 is a schematic cross-dona1 view illwtmhg one example of the
power transmission belt.
[Fig. 23 Fig. 2 is a schematic view for explain@ the m&g method of the
transmission efficiency.
[Fig. 31 Fig. 3 is a schematic view for explaining the rneambg method of the
bending stress in Examples.
[Fig. 41 Fig. 4 is a schematic view for explaining tbe measuting method of the
friction coefficient in Examples.
[Fig. 51 Fig. 5 is a schematic view for explaining the high-Ioad running test in
Examp1 es.
[Fig. 61 Fig. 6 is a schematic \iiew for explaining the high-speed numing tat in
Examples.
[Fig. 7j Fig. 7 is a s c h d c view for explaining the dd%V MlTdng tsst in
Examples.
MODE FOR CARRYING OUT THE INVENTION
The rubber composition of the present invention is usefui for elmtihg the
transmission efficiency and i. useful for forming at least one rubber layer selected fiofn a
compression rubber layer and m ~ ~ i brublbeer la pr (particukIy, at least a
compression rubber layer) of a belt This rubber composition contain~a rubber
component, a fatty acid d d e , and a short fiber.
(Rubber Component)
The mbber component ofthe rubber compositi~nin dudesI for example, a
vulcanizable or crossl~ableru bber, and examples thereof inelude a diene-based rubber
(e.g., natwd rubber, isoprene rubber, -me rubber, chloroprem.rubber, styrene
butadienc rubber (SBR), acrylonitrile buhdiene rubk (nitrile rubber), hydrogenated
nitrile rubber), an ethylene-u-olefiu dastnmer, a chlomsulfomtad polyethy].ene rubber, an
SlkyCated chlorosulfonated polyethylene rubber, an epichlorohydrin rubber, an acrylic
rubber, a silicone rubber, a urethane rubber, and afl~tombk. These rubber componeats
may be used atone or in combination of two or mare "thereof.
P r e f d rubber components are an ethylene-a-olefh elastomer (an ethylene-aolefin-
based rubber such as ethylene-pmpylene rubber (EPR) and ethylmepropyb
dime monomer (e.g., EPDM)) sad a chlamprae rubber. A particularly preferred rubber
component is a chlorope rubber. The chIoroprem rubber may be a sW-modi5ed
type or a non-sulk-modified type,
(Fatty Acid Amide)
The fatty acid amide is a thmmdly/cWcally stable soIid surthctant having a
long-chain fatty acid group (e.g., a fatty acid group having a carbon number of
approximately from I 0 to 40) and an d d e group in its molecule. Examp1es o f the Wy
acid amide include a sa-ed or unsarturated higher fatty acid monoamidc such as
saturated or unsaturated higher htty acid amide such as lxkmmide, mchida;tni&,
stearamide, hydroxyst~dep,a hitamide, myristarmide, lauramide, erucamide,
oleamide and recinoleamide; a s a t m t . 4 or mmturated higher fatty acid b i d d e such as
alkyIenebis saturated or unsanvated bigber fktty acid d e {e.g., a Ci-l0 alkylehebis
saturated or unsaturated hi* htty acid d d e such as m&ty1enebisf&twmide,
methylenebislmramide, m e t h y l e n e b i s h y d r ~ ~mdeeth~y 1enebisoIGamide,
ethylenebisbehenamide, ethylenebisskarmide, ethylmebiscapryl~de,
ethyleneMscapramide, ethylenebis1adde, isoskmmide, ethylencbhmmnide,
ethylenebisolmide, tetrmethy1enebimde, h e x ~ y l e n e b i s b e h ~ d e ,
hexamethylenebisstdde, hexmethy1enebishydroxy~&, and hexmethylentl
bisoleamide); and a bisamide of a di&xyIic acid and a seaufaesd or unsgaPated bigher
amine (e.g., a bisarnide produced by the reaction of a C6.12 micarbaxylic acid and a
sauted or unsaturated higher amine, such as N,Ntdstearylsd.i@&~ N,WdistearyIsebacamide,
N,N-dioleyladipmide, and N,N1-dioleylsebacamide).
AIso, examples of the fatty acid mide hclude, in addition to m ammatic
bisamide (e-g., a bisamide of an aromatic dimhe and a saturated or msatwated higher
fatty acid, such as xylylenebisst~ded, a bisamide of an aromatic dicarboxyIic acid
and a saturated or unsaturated higher amine, such as N,Ndfsteary1phMamide), a
substituted amide (a higher fatty acid amide in which a saturated or uawtmtd hifatty
acid residue is midebonded to the nitrogen atom of an d d e group, such as Nlauryl
lauramide, N-palmityl pgfmitamide, N - m l smarnide, N-stmy1 oleamide, Noley1
stmadde, N-stearyl erucamide, and N-stwyl hydroxysteetrmide), an stet wide
(an ester arnicle: in which a higher fatty acid is ester-bonded to the hydroxy1 group of an
dkanolamine and a hi@a fatty acid is amidabonded'to the amino group of the
alkanolamine, such as ethanolamine d i b e w ehuwIamine tiistearate, etbnolamine
dipalmitate, propanoI- dist9&, and propanolamine dipahi-), ran allcmblide
(methylolamides such as methyl01 higher f&y acid monoainide, e.g, rnethylohsmide,
methylolbeh~tlea;n d a N-hydroxy CH 1- higher Wty acid momamide such as
stearic acid monoetbauolzunide and m i c acid man-llamide), and a substituted m a
(a substituted urea in which a higher fatty acid is &&-bonded to the nitrogen atom of
urea, such as N-butyl-N-st~~yIN~-ap,h myl-N'-steatyluwaN,- stearyl-N'-steary1~
xylyleaebisstearyI~t oluylenebSs~Iureah, ~ t h y l e n e b i s s ~ 1 maand,
diphenylmethanebis~Iurea). me firm add ami& preferably cbnt&s at least one
member selected &an a saturated or ams-ed long-chain farty acid amide aud a
saturated or unsaturated lonp-chain fatty acid ester ad&. heidentally, in such a fhtQ
acid amide, the carbon number of the higher fhtQ acid and higher amine may be
approximately from 10 to 34 (e.g., fimn 10 to 30, p&eab1y 10 to 28, more pderttbly
&om 10 to 26, and still more prefmblly h r n 12 to 24). These fatty acid amides may be
used done or in combination twa ar more there~f.
The melting point of the fktty acid amide may be selected in a range of
approximately from 50 to 200°C and muatly, m y be qproxbwte1y hm 65 to 15W,
preferably fiom 75 to 1 30°C (age, fiom 80 to 120°C), and more prefd1y h m 90 to
11 0°C (e.g., fiom 95 to 105°C).
The fatty acid amide functions as a dispersant for the short fiber and has an
advantage of enhancing the dispaibility and arlentation (ofientation in the beft width
diition) of the shnt fiber in the mbba composition and inmasing tho lamal presme
resistance and weax mistance of the compression iubber layer. In addition to the
function as a dispersant, the farty acid amide fimctiom also as an intenmi lubricant in the
rubber composition and tends to dew the modulus ofthe mabix mbk wmponcxtt and
make the matrix component flexible, but by the combination with a shoa fiber, reduction
in the modulus urn be suppressed. That is, fhanlcr to the combinstion of a fatty acid
arnide snd a short fiber, not onlg the matrix om~ponmto f the compression rubber layer is
made flexible but also a campression rubber layer exce1Ie;st in ttxe mechanical
characteristics can be formed. In particular, the combination of a fatty acid amide a d a
short fiber cgxl eliminate the need for raising the hanines of the oompssian rubber layer
by blading a large amount of a shnt fiber or a reinp~rcinga gent such as carbon black and
enables improving the bending fatip and fuel saving gxdbmance dtho belt (in
particular, the fuel saving performance in the csss where the belt is wound atmd a small
pulley and caused to m).
Furhennore, the: fatty acid arnide blooms Cprecipitata) or bleedslout to the
surface (the friction traasmission d a c e coming into cbntaet With a pulley) from the
inside of the compression rubber layer and hotions as an external lubricant to reduce the
friction coefficient on the rubber layer suf'e. Momva, the fatty acid mi& blooms or
bleeds-out to the surfbe of the cornpression rubber layer over a lorig duration, so that a
low friction coefficient can be maintained over a long period of the. In turn, the rubbet
layer surfie smoothly makes Hction with a pulley, as a result, the rubber layer am be
prevented frum being subjected to the action of an excessive shear force by a pulley during
belt m i n g and the durability of the belt can be imbnd. Also, in use 9s a variable
speed belt whm the belt moves up and down in the pulley radial Man on the pulley,
the fuel saving perfoxmame om be more effectively enhanced. Incidentally, if tbe fiction
coefficient is high, the sheax fom received bin a pulley is increased and s e p d o ~or.
cracking is generated due to largo deformation or the like of the compression rubber layer,
leading to a short life af the belt. In addition, far example, in the &dimant of coating
a lubricant on the rubber layer surfhe, a fiction-reducing effect of the IvWcant may be
exerted at the initid stage of kIt d n g but when the belt is caused to m for a long tima,
the lubricant is scattered or worn aff and the fjriction-reducing effd is last.
Among the fm acid amides, a fatty acid moaaamide, for example, a saturated or
unsaturated fatty acid moaodde having an amide group at the terminal, in which tbe
number of carbons constituting the long-chain fw acid residue is d,a.g.,
approximately from 10 to 26 Cparticddy fiom 12 to 24), is prefed 8s compared with an
alkylene bisarnide. The reason thaefor is not clearly know11, but it is # that in the
case where the long-chain fatty acid residue a long structure, that b, the c8tbort number
is large, concentration of aslids gmup in tllc molecdar becomes ref~velysm all rmd the
chemical interaction between the amide group of a fatty acid amide and the adbesive
component of a short fiber is decmmd, and in the cme whae a long-chain fatty mid
group (e.g., the total carbon number is lergs .ad exceeds 40) is pnsent on both s i b as in
an alkylene bisamide, the chemical iatmdm between the smidc group da btty add
arnide and the adhesive component of a short fiber is decreased, giving rise to reduction in
the adhesiveness of a short f i b to a rubber component. Incidentally, among the fatey
acid amibs, an ester d d e is also pfmed. In this Hght, the mel@ point or t f i e d
characteristics of the fatty acid mde may be also mlewant to the adhesiveness or the like
between a short fiber and a rubber composition,
The ratio of the &ffy acid amide is ap-y, h m 0.5 to 10 parts by mass,
preferably from 1 to 8 paxts by mass, more p ~ h b lfyio m 1.5 to 7.5 prnts by mass (e.g,,
from 2 to 7 parts by mass), and usually ftom I to 6 parts by mass, pm 100 part% by mass of
the rubber component. If the amount of the fktty acid amide used is too d,bloom ing
to the rubber layer surface may be lessened and the effect: of reducing the .fiction
coefficient may be low, whereas if it is too we, 4a mcess fatty aeid amide not
participating in the interaction with a short fiber (adhesion-treated short fiber) may
function as an i n t d lubricant and the modulus (in ~~, the moddus ixl the
compression direction) of the matrix component may be greatly demawd. Incidentally,
even if the mount of the fatty acid a d & wed is too large, a friction-reducing &ect
reflecting thereof is not obtainad and this is tconomically disadvantageous.
(Short Fiber)
As for the kind of the short fiber, use cim be g&y made of a synthetic fiber
such as polyolefin-based fiber (e.g., polyethylene fiber, polypropylene fiber), plyamide
fiber (e.g., polyamide 6 fib3p olyamide 66 fiber, polyamib 46 fiber, d dfiber ),
polyalkylene arytate-based hber (e.g., a Cw dkylme CM4 arylate-bd fiber such as
polyethyIme terephthdate (PET) film and polyethyhe naphthalate (PEN) fiber), vinylon
fiber, polyvinyl alcohol-bd fiber, and pol~aphenylcnebe~~~bisoxa(zPoBlOe ) fiber; a
natural ftber such as cotton, hemp and wool; and an inorganic fiber such as carbon fiber,
These short fibers may be used alone or in combination af€wu or more thereof. Among
these short fibers, a synthetic fiber or a naturd fiber, particularly a synthetic fiber (mch as
polyamide fiber and poIyaU@eae atylate-based fiber) is more pefmd, and in view of
being rigid and having high strength and modulus, a &art f i b containing d least an
amid fiber is paefened. The mamid short fiber also has high wear mistancg* The
armid fiber is comnercilly available under the trade names of, for example, "Conex",
"Nomex", "Kevlar", "Technora", and "w".
The short fiber is preferably embedded in the cmpxession rubber layer with
orienting in the belt width direction so as to keep the b1t hxn compressive deformation
due to the pressing of a pulley. Also, by protmding a short fiber fhm the surfhe af the
compression rubber layer, the fiction coefficient on the s u r f " can be.decreased to
suppress a noise (sound production) or reduce the wear resulting from rubbing with a
pulley. The average length ofthe short fiba is, for example, from 1 to 20 mm, p~krabIy
from 2 to 15 ram, more preferably frm 3 to 10 mm, and may be approximately from 1 to 5
mm (e-g., &om 2 to 4 mm). If the avaage length of the short fiber is less than 1 mm, the
mechanical characteristics (e,g., modulus) in the grain direction cannot be sufIicimtly
enhanced, whereas if it exceeds 20 mm, a dispersion Mure of the short fiber in the rubber
composition may o m to cause crackhg in the rubber sod the belt may be damaged early.
The ratio of the &art fiber may be selected in the w e of qproximately 6.am 5
to 50 garts by mass per 100 parts by mass of the rubber cmponent and may be usually
from 10 to 40 parts by mass, preferably from 15 to 35 parts by mass, more preferably,
approximately h r n 20 to 30 parts by mass, and stiU more prefkabIyI approximatidy from
15 to 30 parts by mass (from 15 to 25 parts by mass). Ifthe amount of the short fiber
used is too small, the mechanical ~ c ~ s t iocf thse c ompression rubber layer are
insufficient, whereas if it is too Imp, the bending fatigue ofthe c o ~ s i ornu bk kyu
deteriorates (the compression rubber layer becomes bad md the bending stress is
increased), as a mdt, there arises a problem that in the state of the belt winding diameter
being small, the loss due to bending becomes large and the fuel saving p e r f i ~ mis ~ ~ ~ ~
reduced. Also, if the m~unot f the short fiber used is too large, there arises a problem
that the dispersibility of the short fibr in the rubber camposition is d e a e d to cause a
dispersion failure, and cracking stating from that portion may occur early in the
compression rubber layer.
Incidentally, probably because the fatty acid amide has an ad& bond and a longchain
fatty acid residue, the adhesiveness h e n the shartdber d the rubber
compositim (matrix rubber: the rubber composition txc1udhg the shurt fik) constituting
the wmpnssion rubber layer can be enhanced. In particular, in the ease where an
adhesion-treated short fiber is used as the short fibers the adhesive mmponent an the
surface (outer layer) thereof chemically interacts with the fatty add amide, whereby the
adhesiveness of the short film to the rubber campsition (matrix rubber) comththg the
compression rubber hyer can be incrcmed. In tPng the; modulus, tensile strength and tear
strength of the compression rubber layer can be more enhanced.
h view ofdispersibility and adhesiveness of the short fiber in the rubber
composition, at last a part of thc short fiber is preferably adhesion-treated (m srfacetreated).
In this comecti~)ni,t is not required that all shat fibers are adhesion-treated, and
an adhesion-treated short fiber and a nm-adhesion-treated short fiber (nonltreated short
fiber) may be mixed or used in cornb'iation.
The adhesion treatment of the short fiber can be performed by using various
adhesion treatments, for example, a treatment solution wnhhing an initial condensate of
phenols and formdin (e.g,, prepoIymer of novolals- or nsol-type phenol lre~iaa)~ tr eatment
solution containing a rubber component (ar a latex), a treatment soI,ution containing the
abovedescribed initial condaisate and a r u b k component (latex), or a treatment solution
containing a reactive compound (adhesive compound') such as a same coupliqg agent, an
epoxy compound (e.g., epoxy resin), and an isocyanate compound. In a p r e f d
adhesion treatment, the short fiber is treated with a tre&ment solution containing the
above-described initial condensate and a rubber component (!atex), pticuiarIy at least
with a resumin-formalin-latex @VL] solution. These treatment solufions may be used in
combination and, for example, the short fik may be pretreated with rt conventional
adhesive component, for example, a reactive campuund (adhesive cornpund) such gs
epoxy compound (e-g, epoxy &) and isucyamte compound, stnd then treated with an
RFL solution
In the case of treating with such a tmatp~rnsto lution, particularly with an RFL
solution, tbe short fiber can be strongly adheted to the mbber cornpsition, ?'he RFL
solution is a mixture of an initial condensate of resmin and fomral&hy&, and a rubber
latex. The molar d o of resorcin to formaldehyde is may be set in a range where the
adhesiveness between the rubber and the short fiber can be enhanced, fix example, may be
set to be approximate1y, fomerilatkr = fiom 1/0.5 to 113, preferably fbm 110.6 to 1R.5,
more preferably h 1E0.7 to 1/I .5, and my be approximately from 110.5 to 111 kg.,
fiom 110.6 to 1 10.8). The kind of the latex is not particularly limited and my be
appropriate1y selected finm the above-dadbed rubber components cbpedkig on the kind
of the rubber component that is the targd of adhesion. For examph, in the case where tb
rubber composition working out to tfie target ofa dhesion &s chlompr~ru bber as
the main component, the latex may be a dimebased rubber (e.jj., aural mbk, isoprene
rubber, butadiene rubber, chlomprene rubber, styrene butadifme rubber (SBR), styrenebutadiene-
vinylpyridine terpolymq acrylonitrile butdiem rubber (nitrile rubber),
hydrogenated nitrile rubber), an ethyleneeu~leikeh sbmer, a chlomoulfon&kd
polyethy1ene rubber, or an allq4at:ed chlomsulfamtad polye€hylene mbba These latexes
may be used done or in combination oftwo or moretheof. The pnfcrrsd latex is a
diem-based rubber (e.g., styrene-butadine-vinylppidinet erpolpmer, ~Maroprene~ b k
and butadiene robber) or a ohlorosulfQnatad polyethylene rubber, d in vim of mars
enhancing tbc adhesiveness, s styrem-butadiene-UinyIpydinet apo1ymer is @dm
In the case where the short fiber is adhedm-treated with a treatment solution containing at
least a styrene-butadienecvinyIpyridintt erpolymcr (e.g, RFL solution))t, he adhesivcnesr
between thc rubber composition (eg, d o m e rubber wmposition) and the short fiber
can be enhanced arid at the same time, thanks to the combining with a fatty acid amide, the
adhesiveness beween the rubber compositim and the short fiber can be more in-.
The ratio of the initid condensate ofmsorcin and formalin may be approximstely
from 10 to lOOpsrts bymaps(e.g.,fmm 12ta50parbbymags,e0dprzfexably~l5to
30 p m by mass) per 100 paw by mass of the lubber pdon of the latex. Incidentally,
the total solid content ~oncentrationo f the RFL s01Utioa can be adjusted in thc mnge df
fiom 5 to 40 mass%.
The adhesion rate of the adhesive: component (solid content) to the short fiber is,
for example, &om 1 to 25 mass%, pderab1y from 3 to 20 mass%, more preferably from 5
to 15 mass%, and may be approximately hm 3 to 10 mass% (e.g., h m 4 to 8 mass%).
If the adhesion rate of the adhesive component is less than I mas%, the dimbifity of
the short fiber in the tubber composition or the sdhesivene~gb etween the short fiber and
the rubber compsiti~nis insufficient, whereas ifit is as high as exceedhg25 mass%,t he
adhesive component firmIy fixes fiber film- to each other aad the dispersibility may be
rather reduced.
The method for preparing the adhesion-tmbd short fiber is not perticuiarly
limited, and there may be ulikd, for example, a method where a cuntinwus fiber of
muftifilament is dipped in an adhesion treatmat solution, dried and then cut into a
predetermined length, and a method where an untreated short: fiber is dipped in an adhesion
treatment solution for a @etembd .time and after removing an excess adhesion
treatment solution by centrihgal separation or the like, and dried.
(Additives such as Vdcatlizing Agent)
The rubber composition may contain, if desired, a v u l m agent or
crosslinking agent (or a crosslinking agent system), a co-cross- agsnt, a
vulcanization aid, a v u f ~ t i o ancc eIer&tor,a vul-on retarder, s metal oxide (e.g.,
zinc oxide, magnesium oxide, calcium oxide, barium oxide, iron oxibe, copper oxide,
titanium oxide, aluminum oxide), a reinforcing agent (e.g., carbon black silicon oxide such
as hydrous silica), a filler (e,g., chy, calcium carbom talc, mica), a so&m (e.g, oiIs
such as p a r f f i oil and naphthene-based ail), a processing ageat or processing aid (e.g.,
stearic acid, metallic stemhe, wax, pmffi), an anti-aging agent (e,g., antioxidant, antiheat
aging agent, flexural cracking intuiitor, ozone &gmhtiori inbitor),.a coloring agent,
a tackifier, a plasticizer, a coupling agent (e.g., silane coupling agent), a Scab'rlkr (e.g.,
ultraviolet absorber, heat stabilizer), a flame retardant, an antistatic agent, and the Iike.
Incidentally, the metal oxide may be ztct as a c r o s s 1a~ge nt.
As the vulcanizing agent or crosslinking ageat, a con-onsl component can be
used depending on the kind of the rubber wrnpononf and examples tbereof inelude the
above-described metal oxide (e,g., mapesimn oxide, zinc oxide), an organic peroxide
(e.g., diacyl peroxide, peroxywer, diaIkyl peroxide), and a sulfur-based vulcanizing agent.
Examples of the sdh-based vulcanizing agent include powder sulfur; prmipitated dfh,
coIloid sulfuS insoluble gdfbr, highly dispersible solfin. mi dfur chloride (e.g., sdfm
monochlaride, sullfur dichloride). These mssliuking agents m vul-g agents may be
used alone or in combination of two or m m thmf. In the case where the rubber
component is chloroprene rubber, use can be made of a meal mide (e.g., maghesium oxide,
zinc oxide) as the vulcanizing agent or cmsslinldng agad Incidentaly, the metal oxide
may be used in comb'ion with another vul- agent (e.g., sulfur-based vulcanizing
agent), and the metal oxide and/or the ~=~ vul-g agent may be used alone a
in combination with a vulwnhtioa accelerator.
The mount of the v u l d ea .used may be selected in the range of
approximately fmm 1 to 20 parts by mamr per 100 parts by mass of the rubba eompunent,
depending on the kinds of the wlwnbkg agent and the rubber component. For example,
the amount used of the o@c peroxide as a wlcauizing agent may be selected in the
range of approximately, fiom I to 8 parts by mass, preferably hm 1.5 to 5 parts by mass,
and more preferably from 2 to 4.5 parts by mass, pa 100 parts by mass of the rubber
component, and the amount of the m d oxide used may be seIected in the mge of
approximately, from 1t o 20 parts by mass, prp:f-,lgf rom 3 to 17 parts by mass, and
more preferably from 5 to 15 parts by mass (e.g., $om 7 to 13 p& by mass), per 100 paxts
by mass of the mbhr component.
The ca-crosslinking agent (crosslinking aid or oodcaniag agent (GO-qu))
includes a known crosslinking aid, and examples thmeof include a polyfunofional
(isu)cyanmte (e.g,, triaUy1 isoeyanmte (TNC),t ridyl ~yanwafe(T AC)), a plydime
(e-g., 1,2-polybutadiene), a m d salt of an ~a~ carboxylic acid (e.g., zinc
(meth)acrylate, magnesium (meth)~~ryIateo)x, imes (e.g., quin~ned ioxime), @dines
(e.g ., diphenylguanidine], a polyfbnctitmal (meth)acrylaie (e.g., ethylene glycol
di(rneth)acryIate, butane diol di(meth&aylate, ~ethylolpropanett i(me&)acryIate), and
bismaleimides (e.g., an diphatic bimaleknide such as N,N'-1,24yEm bismaleimide and
1,6'-bismaleimide(2,2,4~~yI~cycJaon; a rene bimdeimide or aromatic
bismaleimide, such as N,N'-m-phenylme bismaIeimide, 4-methyl- 1,3-phenylene
bismaleimide, 4,4'-diphenyImethane bideimide, 22-bis[4-(4-maleimidopheaoq)-
phenyllpropane, 4,4'-diphenyl ether bisrrdeirnide, 434'-diph.eny1sulfotre bismaleimide, and
1,3-bis(3-mdeimidophenoxy]hne). These cmlhkhg dds my be used alone or in
combination of two or more thereof. Among thwe crossIinking aids, bbmdeimides (an
arene bismaleimide or aromatic bismaleimide, mh as NJT-rn-phenylene dhdeimide) are
preferred. By the addition of bdeimides, the ms&g d ; e p can be raised, and
sticking wear and the like can be prevented.
The ratio of the co-cross- agent (crosslinldng aid), In terms of the mlid
contet, m y be selected in the range of, fm example, approximately $+om 0.01 to 10 pars
by mass per 100 pprto by mags of the lubber component and may be qprbximately, fiom
0.1 to 5 parts by mass (e.g, from 0.3 to 4 parts by mass), and prefdly h m 0.5 to 3 parts
by mass (e.g., 0.5 to 2 parts by mass).
Examples of t h vulardzation acceImtor include a thiuram-bmed accelerator
(e.g., tmamethykhiuram monwsuJfide 0kt,ramethy1tb it~ramd isulfide (TMTD),
tetmethylthiuram disuEde (TED), tetmbutyIihiuram didfide (mTD),
dipentamethy1enethiuram bimsuffide (Dm, N,W-dimethyl-N;N'-diphmyfthiura~
disulfide), a thkzole accelerator (e.g., 2-mercaptobttnzothi8201e, a zinc salt of 2-
mercaptobem~azole,2 -mercaptotblwhe, diievumtbiazyl disuIfidc, 2-(4'-
morpholkodithio)bthi8201e)~a suIf-de-based derator (e.g., Nc~yolohexyl-2-
benzothiazyl sdfenamide (CBS), N,N'-di~lohexyI-2-be~1~0thiaszuyllf edde), a
bismaleimide-based accelmator (e,g., N3'-m-phenyIene bideimide, N,N- 1 ,Z-ethylme
bismaleimlde), @dines @.g., diphenylgtmidme, d i - o - t o l y l ~ ~a) u,r ea-bd or
thiourea-based accelerator (e.g., ethylene thiowa), dithiocarbamatee, and xanhbs.
These vulcanization acceleratrns may be wed alane ar in wmbition of two or more
thereof. Among these vulcanization ac~elerabrsT, NIP, DPT'T, CBS and the like are
used for general purposes.
The ratio of the v u l d t i o n accelerator, in terms of the solid con-$ may be
approximately, for example, hm 0.1 to 15 parts by mass, pfkrably from 0.3 to 10 parts
by mass, and more preferably fiom 0.5 to 5 pa&i by mass, per 100 parts by mass sf the
rubber component.
The amount of rhe rehforciq agent (e,g., carbon black, silica) used m y be
approximately fhm 10 to 100 parts by mass (pafersbly h m 20 to 80 parts by mass, and
more preferably hm 30 to 70 pafts by mags) per 100 parts by mass of the tow amount of
the rubber component Also, the amount of the softener (oils such as mphthene-based
oiI) used may be approximateIy, for example, h m I to 30 parts by mass, and preferably
fkom 3 to 20 parts by mass (e.g,, from 5 to 10 parts by maas), per I00 parts by mass of the
total amount af the rubber component. The mount of the anti-aging agent used my be
approximately, for example, from 0.5 to 15 parts by -9, prefwablY h m 1 to 10 parts by
mass, and more preferably fkom 2.5 to 7.5 parts by rnass (e.g., from 3 to 7 parts by mas),
per 100 park by mass of the total amount of the rubber wrnponent.
(Structure of Belt)
The structure of the power tmmrhsion belt is not pwtieularly limited and may be
sufficient if it is a belt having the abovedescribed compression rubber layer @Is of
contacting with a pulley. The power trmmision belt has, in many cases, m h i v e
rubber layer having embedded therein a core win in the lom*tudd dimction of the belt.
and a compression rubber layer fonned on cme sudkce of tbe adhesive rubber layer, aad
may further have an extensible rubber layer formed on another surface of the adhesive
mbba layer. Here, the compression rubber layer and tbc extensible rubber layer may be
formed of the above-described rubber composition.
Fig. 1 is a damtic m s s - d o l view ilIwtmthg om example of a power
transmission belt. In this example, a car wire 2 is embedded in an adhesive rubber layer
I, a compression rubber layer 3 is stacked on one smhx of the adhesive rub& layer 1,
and an extemib1e rubk layer 4 is stacked on mother mfm of the adhesive rubber kym
1. Incidentally, thc core wire 2 is embedded iategralIy in a state of being sandwiched by a
pair of adbesive rubber sheets. Furthmmc, a iddo~cingM uic 5 is stacked rm the
compression rubber layer 3, and a cog pat 6 is formed by a shaping die wifh cog, The
laminate of the compression rubber layer 3 and the reinforcing Writ 5 is integrally formed
by vulcanizing a laminate of a reinfming fabric aszd a compression rubber layer sheet
(unvulcanizd rubber sheet).
Incidentally, in the example above, an example of a cogged V-belt is illu&&d,
however, not iimited to this sbnrctmz but vasiow belts (e.g,, a raw edge belt, a V-ribbed
belt) having the above-de~bedco mpression nrbbw layer can be applied.
(Adhesive Rubber Layer)
The rubber composition for forming the adhesive rubber layer may conbin,
similarly to tire above-described rubber composition, a rubber component (e.g., a
chloroprene rubber), a vuldzing agent or cmsliaking agent (e.g., a metal oxide such as
magnesium oxide and zinc oxide, a sulfirr-based WIG- agent such as dfitr), a cocrosslinking
agent or crosshkhg aid (e.g., a malcimide-based crosslinking agent such as
N,N'-in-phenylene dimaleimide), a vul-on accelerator (e.g., TMTD, DPT'T9 CBS), a
reinforcing agent (e.g., carbon black, silica), a sofiener (oils such as naphthm-based oil),
a processing agent or processing aid (e.g., stedc acid, metallic stearate, wax, psrafIin), an
anti-aging agent, en adhesiveness improver (e.g., a msorcin- farmaldehyde co-cundenwte,
an amino resin (a condensate of a nitrogenantaking cyclic compound and formaldehyde,
such as, a melamine resin such as hexamdhyloLnel&e and hexaallm~ylmelamine
(e.g., hexarnethoxymethylmI~h, exdmb~&yhel&e), a utea resin such as
rnethyiolwea, and a benzogwmmim msia such as methylolbenza-e resin), a GOcondensate
thereof (c.g., a marcin-mdamine-fod&hyde GO-condexisate))a, filler (e,g,,
cf ayy cdcium carbonate, talc, mica), a wloring agent, a tackifia, a plasticizer3 a coupling
agent (e.g., a silane coupling agent}3 a stabiha (e.g., an ultraviolet absorber, a heat
stabilizer), a flame retardant, an antistatic agent, and the like. Here, in the adhesiveness
I improver, the resorcin-formaldehyde w-condeasate d the mino resin may be an initial
condensate Onepolymer) of remrcin andlor a nitrogen~containingc yclic comp~undsu ch as
melamine with knnafAehy.de.
Incidentally, in this rubber compositim, a m b kl ~thfe same system [e.g., dimebased
rubber) or the same type (e.g., chloroprene) as the rubber component in the rubber
composition of the compression nrbber layer is used as the rubber comp6nent in many
cases. Also, the amount wed of each of the vulcanizing agent or c r o s e agent, the
co-crosslinking agent or crosslmkhg aid, the vulcanization B C C C ~th~e r,ei nforcing
agent, the softener, and the anti-aging agent m y be selected &m the samt range as in the
rubber composition of the compression rubber layer. Furhamom, in the rubber
composition of the adhesive rubber lam, the amount of the pmcahg agent or processing
aid (e,g., stearic acid) used may be approximatelys fiom 0.1 to 10 parts by mass, preferably
from 0.5 to 5 parts by mass, and more pderably fbm I to 3 parks by mass, pa 100 pats
by mass of the rubber component. Themoltllt of the adhesiveness hpver (e.g., a
resorcin-fddehyde ~090ndas~hee, ~ t h o q m & y h e I ~W) m yb e
approximately, fiom 0.1 to 20 parts by mass, prefdly hm I to 10 parts by mass, and
more preferably fkom 2 to 8 parts by mass, per 100 parts by mass of the rubber c o m ~ f .
Examples of the fiber constituting the core wira include fie same fibers as the
fi bns exemplified as the short fiber'abovc. Amrmg those fibers, in view of ldgh d u s ,
a synthetic fibex such as polyester fiber containing, a the main constitutional unit, a C24
alkylene arylate such as ethylene terephthb and ethykne-2,6-naphthalat.e ( p 0 1 ~ I e n e
arylatc-based fiber) and aramid fiber, and an inorganic fiber such as carbon fiber are used
for general purposes, and a polyester fiber CpOIyethylene terepwalate fibers, ethyl-e
naphthalate fibers) and a polyamide fiber are @d. The fiber may be a muItiment
yarn. The fmeness of the multifilament yarn may be appmxbate1y, for example, from
2,000 to 10,000 denier (in partidar, from 4,000 to 8,000 Wer).
As the core wire, usually, a twisted card (e.g., ply twist, swe W, Mg's twist)
using a multifilament yarn can be used. The average wire diameter of the core wire (the
fiber diameter of the twisted card) may bt appm-ly, for example, h m 0.5 to 3 mm,
preferably from 0.6 to 2 mm, and more preferably &om 0.7 to 1.5 flm. The core wire is
embedded in the longitudinal direction of the bdt, atld may be embedded side by side at a
predetermined pitch in parallel with th longitudhd direction of tbe belt.
In order to improve the adhesimess to ths rubber component, the oon wire m y
be subjected to various adhesion treatments, similarly ta the abovedescribed short fiber,
for example, to an adhesion treatment with a resorch-.Po&-lstsx solution (RFL
solution]. The adhesion treatment may be gendy @med by dipping the fiber in an
RFL solution and heating/dqbg to uniformly form an adhesive layer on the smfacc.
Examples of the latm, of the RFL solution include the sams rubber componcntl as the htex
of the abovbdescribed Rm. solution, d cbl~ropmea~ s tyrene-butadiene-vinylpfidine
tapolymer and the like m preferred The core wire may be subjected to s pretreatment
@re-dipping) with a reactive eompouad such as epoxy compound aad isocyanate
compound before the RFL treatment or to an adhesion treatmetit such as gum treatment
(overcoating) gAer the RFL treatment and then embedded in the rubber layer-
In the power transmission belt, a reinforcing fhric may be stacked on the surfhe
of the compression rubber layer and/or the axtenslible rubber layer. 'Ihe midarcing fabric
can be formed by staking a f&o m a t d such as woven fabric, wide angle canvas,
knitted fabric, and nonwoven fjibric CpreferabZy woven fabric) on the surfaGe of the
compression rubber layer and/or the exteasib1e rubber layer, and, if desisd, it may be
subjected to the abovedescribed adhesion matment, for example, a treatment with an RFL
solution (such as dipph treatment), or subjected to Hction ofrubbing an adhesive rubber
into the fabrio material ox stacking (coating) of the adhesive rubber and the Writ mate:rid,
and then sacked on the surfime of the compression rubber layer and/or the extensible
rubber layer.
(Transmission Efficiency)
In the case of wing a power tmsmhsion belt having the above-described
compression rubber layer, the trammission &ciacy can be greatly enhaoced. The
transmission efficiency is m indicator of the transmission of rotary torque from a drive
pulley to a driven pulley by a belt, and a higher tnmmissim efBcirmcy means that the
power transmission Ioss uf the belt is d e r and the fbd saving perfommce is superior.
In a biaxial layout illustrated in Fig. 2 where a belt 1 I is hung between two pdIeys of a
drive pulley (Dr.) 12 and a driven pulley @n.) 13, the transmission efficiency can be
determined as follows.
Assuming that, in the drive pulley, the rotation speed is pl and the pulley radius is
rl, the rotary torque TI of the drive pulley can be expressed by plxTe*rl. Te is ad
effective tension obtained by sub~~~ttihne lgo ose-side tension (the tension Tb on the aidc
of the belt ruming toward the driven pulley) from the tight-sids Won (the tension Ta on
the side of the belt nmning toward the drive pulley). ShniLrly, awmhg that, in the
driven pulley, the rotation sped is pr and the pulley radius is g the mtary torque 4 of the
driven pulley is expressed by prxTmr2. ThenXt hc trawdssfon eEcien~yT fll is
calculated by dividing the rotary torque T2 of the drivexi pulley by fhe rotary torque TI of
the drive pulley and um be represented by the foIIo* cqmtiofi (1):
Incidentally, the trmsmission~efficiency does not have a value of '1 or more in
practice, but a vdue closer to I hdhtes that b power transmission loss of the belt is
smaller and the he1 saving perfommce is superior.
The production mdod of the belt is not particularly Iimitd, and a conventionid
method can be employed. For example, a laminate of u n v u l e Wer layers in the
above-described configuration, in which a core wire is em-d, is formed by a shaping
die and vulcanized to shape a kh sleeve, and the v u l c d d belt slave is cut into a
predetermined size, whereby the bet il.Xwtmbd in Pig. I can be fmd.
EXAMPLES
The present invention is described in grater detail below based on Examp1es, but
the present invention is not limited to these Exmp1es.
Examples 1 to 7 and Comparative Examples I and 2:
(Formation of Rubber Layer)
Each of the rubber oompasitions shown in Table 1 ( c o m ~ s i arnu bber layer,
extensible rubber layer) and Table 2 (adhesive rubber layer) wtls prepared by performing
rubber kneading by means of a known method mch as Banbury mixer, and the hdd
rubber was passed through a calender roll to produce a rolled sheet (compression rubber
layer sheet, extensible rubber layer sheet, adhesive rubber layer sheet). Example 1 and
Example 3 are exampIes different in the content of the d d short fiber, Exmples 2 to 6
are examples differat in the content of the fatty acid d d e (from 0.5 to 10 parts by mass),
and Example 7 and h p 1 e 4 axe examples Werent in ihe con.tents of the d d short
fiber and the carbon black. Also, Compdve Example I is an example where in the
formulation of Example 3, a stearic acid ww used in place of the fhtty acid amide, a d
Comparative Example 2 is an example where in place of the fatty acid amide of Examp1e
7, a stearic acid in half amount was used.
In Exmp1es and Comparative Examples, a gtearamide (structural formula:
ClsH37NO) ("hide AP-I", produced by Nippon Kasei Chemical Co., Ltd., melting point:
1 0 1 OC) rn the fatty acid amidel and an a r d short fiber (average fiber length: 3 mu,
"Conex Short Fiber", prodwed by Teijin Techno Products Ltd.) as the short fiber, were
used. InaideataIly, a short fiber having an adhesion rate of 6 mass% as the d i d ooatent*
which was obtained by subjecting the short fiber to an adhesion trwtmmt with an RFL
solution (containing rsorcin and formaldehyde, and, as the latex, a stymebutaditmevinylpfldine
rubber latex), was used, As the RFL soluticm, 2.6 parts by mass of resorcin,
I .4 p m by mass of 37% fbrmalin, 17.2 parts by mass of a stpnebutadienc-vinylpyridhe
copolymer latex (produced by Zeun Corporation), and 78.8 parts by mass of wata were
used. Furthemore, DOS (prod- by DIC Corporation) that is a sebacatebased oil was
used as the plasticizer, SEAST 3 (produced by TOM Carbon Co., Ltd.) was used as the
carbon black, and NOWLEX OD3 @rodwed by S& Chemical Co., Ltd.) was used 8s
the &-aging agent. Also, Nipsil W3 (produced by Tosoh Silica Corporation) Was used
as the silica.
[Table I]
h.
Chlaroprem rubber
Aramid short fiber
Naphthene-based oil
Fatty acid amid@
(skaamide)
b
Magnesium oxide
Carban black
Anti-a gbg agent
Zincoxide
N,N'-m-Phaylenedimalehide
Stearic =id
SuZfitr I
Total
Table 1 (unit: parts by mass)
Example
I
100
15
5
2
4
40
4
5
1
0
0.5
176.5
Comparative
Example
1 I 2
100
1
20
5
0
4
40
4
5
1.
2
0.5
181-5
2
100
20
5
0.5
4
40
4
5
1
0
0.5
180.0
100
30
5
0
4
50
4
5
1
2
0.5
201 -5
3
100
20
5
2
4
40
4
5
1
0
4
100
20 L
0.5 1 0.5 I 0.5
181.5 1 113.5 1 185.5
5
100
20
0.5
189.5
0.5
203.5
6
1 00
20
5 5
7
100
.30
5
10
4
40
4
5
1
0
4
4
5
4
4
SO
4
5
1
Q
6
4
40 40 t
4 4
5 I 5
1
0
I
0
I Total (parts by mass) I 1 75 I
(Production of Belt)
A laminate of a reinforcing ffabric and a compression rubber layer sheet
(unwlcanized rubber) was piaced on a flat die with cogs, in whioh tooth parts aad groove
parts are arranged aIternateIy, with the reWoming &bric fixing down, and pressurized by a
press at 75 "C to produce a cog pad having a pattern of cogs (nat camplete1y vulcanized but
in a semi-vdcarrized state). Next, both ends of thisl cog pad were vertically cut at the top
paR of the cog crest part.
An i n t d mather die having alkmately arranged therein tooth parts and groove
parts was put over a cylindrical metal mold, and tb cog pad was wrapped tkmamand to
engage with. these tooth parts and groove pcsrts and joint at the top part of the cog mest part.
After stacking an adhesive rubber fayea she& (~11uulcEmizendt bber) on the cog pad
wrapped, a core wire was hdidy spun, and another adhesive rubber layw sheet (the same
as the adhesive rubber layer sfieet ,above) and an extensible rubber layer sheet
(unvulcanized rubber) were seqmatidly wped thcmn to produce a shaped body. The
metal mold was covered with a jacket and placed on a vul- carr, and vulcaaidon
was peformed at a temperme of 160°C fam a h e of 20 minutes to obtaia a belt sleeve.
This sleeve was cut in a V-shape by a cutter to obtain a belt havingthe structure ihtrakd
in Pig. I, namely, a raw edge cogged V-belt (size: top width: 22.0 mm, thickness: 11.0 mm,
outer circumferential length: 800 mm) that is a Wble speed belt having cogs on the inner
cixcumferentid side of the Mt.
(Measurement of Physical Roperties of Vulcemized Rubber)
1 ) Hardness, T d e Test, Tear Test
The compression mbkr layer sheet was press-vulcanized at a tempmatme of
160°C for a time of 20 minutes to produce a wlcanizad rubber sheet (length: 100 mm,
width: 100 mm, thickness: 2 mm). The hardness was nr&sured in accoxdan~ew ith JTS
K6253 (2006), that is, a Iaminate obtained by superposing three v u lrub~ber sh mb
on each other was used as the sampl~an d the hardness was m duskg a typeA
durometer hardness tester"
The tensile test was performed in accordance with JIS K6251(2010), that is, a he
vuIcanized rubber sheet was punched out into a dumbbell &ape to pepme a sample, and
the stress (stress at 100% elongation) when the sample was pulled in a tensile tester a d
100% elongated, and the teascity (strength at break) and elmgation (etongation at break) at
the break wen measured. In this rnwwent, the tensile test was perfomxed on a
sample where the short fiba is oriented in pardel with the tensile direction, and a sarnple
where the short fiber is oriented perpendicdar1y. W~thre spect to the mp1e where the
short fiber is oriented in parallel, the strength at brark was measufed, a d with respect tb
the sample where the short fiber was oriented p ~ c ~ Ithey slre,ss a$100%
elongation, the strength at break aad the eIongati0r.t at break were measured,
The tear test was perfumed in accordance with JIS K6252 (2007), that is, the
vulcanized rubber sheet w a pun&d into an angle shape* and the obtained sample was
measured for the tensile and tear strength by a tensile Wkr. In I n s measurement, the
measurement was performed in the state of the short fiber being oriented in the direction
perpendicular to the tensile direction (that is, in the dimdm parallel with the tear
direction).
2) Compression Stress
The compression rubber layer sheet was press-a- at a temperature of ,
1 60°C for a time of 20 minutes to produce a vul- rubber shaped body (kgth: 25
mm, width: 25 mm, thickness: 12.5 mm), The short fiber was made orienthg in the
direction perpendicular to the compression swhe (in the thicksless direction). This
vulcanized rubber shaped body was vdcally sandwiched by two m&d-m& ~omp~ession
plates (the position of the top-side compmsian plate when the vulcanized shaped body
was sandwiched without bebg pressed by the compression plate was defined as the initial
position), the top-side compression plate was pressed against the v d c d rubber shaped
body (pressing surface: 25 mmx25 mm) at a rate of 16 d m i n to cause 20% distortion of
the Mllcanized rubber shaped body, and afta holding tbie state for 1 stmnd, the
compression plate was retmed upward a, fhe initial position Qxelimhary oompression).
From the stress-strain curve m d at the fourth compression test (th~ca ditions were
the same as h the preliminary wmpmsion) after repeating thc prelimby corn-ion
three times, the stress Men the strain in the thickxless direction of the vulcana mbber
shaped body reached 10% was measured as the compression sfmw. Incldentdly, the
preliminary compression was performed three times so as to reduce the variation in the
measured data.
3) Bending Stress
The compression rubber layer sheet was press-vulcanized at a temperature of
160°C for a time of 20 minutes to produce a vulcanized rubber shaped body (length: 60
mm, wid^. 25 wn, thickness: 6.5 m). The &art fiber was made orienting in the
direction pardlel with the width of the vultzmked rubber shaped body. As illustrated in
Fig. 3, this vulcanized rubber shaped body 21 was supported by pIacing it on a pair of mUs
(diameter: 6 mm) 22a and 22b which are rotatable and kept at a distance of 20 mm, and a
metal-made pressing member 23 was put in the width dindon (short fiber orimhiion
dimtion) at the center part on the top surfhe of the vulcanizedrubber shaped body. The
end part of the pressing member 23 had a semicbcula~sh ape of 10 mm h diam&er, md the
vulcanized rubber shaped body 21 can be smoothly pressed by rhr: end part. hing
pressing, a frictional force acts between the bottom ~ B CoBf th e vulcanized rubber shaped
body 21 and the rolls 22a and 22b dong with compressive deformation ofthe vulrubber
shaped body 21, but since the roUs 22a and 22b are set rotatable, the eff~cot f
friction is reduced. The state where the end part of the pressing member 23 is put into
contact with the top surface of tbe Mllcahed rubber shaped body 21 but is not pressing
was taken as "On,a nd fiom this state, the pmsing member 23 was moved down at tr rate of
loo W m i n to pms against tbe top surface of the vulcanhed rubber shaped body 21, and
the stress when the strain irx the thickness direction of the valdzed mbk shaped body
21 reached 10% was m e a s d as the bending stress,
(Measurement of Physical Properties of Belt)
1 ) Measurement of Friction Coefficient
As for the fiction coefficient of the bdt, as illustrated in Fig, 4, one end part of a
cut belt 3 1 was fixed to a load cell 32, a load 33 of 3 kgfw placed on the other end part,
and the belt 31 was wound around &pulley3 4 by adjusting the winding angle of the belt to
the pulley 34 at 45'. Thereafter, athe belt 3 1 on the load cell32 side was pulled at a rate of
30 d m i n for about 15 seconds, and the average fiction eaefiicient on the fi4ction
transmission strrfaos was m m e d . At the r n ~ ~the ptulle,y 34 was fixed to
inhibit its rotating.
2) High-Load R h g Test
I In this Nnning &st, tr-on efhiency of the belt in the oasc of mnnhg in
the state of the belt being @y beat (im the state of khg wound ammd a small pulley)
was evaluated.
The high-load running &st was perfmed, as illustrated in Fig. 5, by using a
biaxial nrrming tester consisting of a drive (Dr.) pulley 42 having a diameter of 50 mm and
a driven @n.) pulley 43 having a diameter of 125 mm, Araw edge cogged V-belt 41 was
hung between respective pdeys 42 and 43, thc belt 41 was nm in a mom-temperature
atmosphere by setting the rotation speed of the drive pulley 42 at 3,000 rpm a d applying a
load of 3 N m to the driven pulley 43. Immediately after rum@, the rotation speed of
the driven pulley 43 was read by a detector, and the transmission ~fficiencyw as
determined by the abovedescribed eddation equation. h Table 3, by taking the
transmission efficiency of Compaative Example 1 as "l", the ttansrnission efficiency of
each of Examples and Comtive Example is shown by a =lafive value. In the case
where this value is larger than 1, the transmission efficiency, that is, the fuel saviq
performance, of tfre belt 4 1 mas judged as high.
3) High-Sped Running Test
In this nmhg test, the transmission efl[iciepoy of the belt in the case of running in
the state of the belt being slid outwad on thp: pulley in the pulley radial direction wm
evaluated. In particular, whim the rotation speed of the drive pulley is increased, a
centrifbgal force strongly acts on the belt. Also, a belt tension acts weakly at the position
on the loose-side (near the region X in Fig. 6) of the drive pulley, and due to a amb'ied
action with the cen- force ab~ve, the belt is likely to fly out outward m the pulley
radial direction at this position. If tb flying out is not smoothIy effected, that is, ifa
frictional force strongly acts between the Mction ~ s s i osnud bx of the belt and the
pulley, power trarnsmission loss of the belt occurs due to the frictional force, and the
transmission efficiency is reduced.
The high-speed ntoning test was performed, rn illustrated m F~B6. , by using a
biaxid running tester consisting df a drive (Dr.) pulley 52 h .a diam eter of 95 mm and
a driven (Dn.) pulIey 53 having a diameter of 85 mm. A raw edge cogged V-belt 5 1 was
hung between respective pulIeys 52 and 53, the bdt 51 was run in a mom-tmatmosphere
by setting fhe rotation speed of the chive pulley 52 at 5,000 rpm and applying a
load of 3 N m to the driven pulley 53. Immediately after running, the rotation speed of
the driven pulley 52 was read by a detectort and the transmission efficiency was
determined by the abovd&tPed c a l d o n equation. In Tablt 3, by taking the
transmission efficiency of Comparative EmpIe 1 as "1 ", the trdssion effidcncy of
each of Examples and Compdve Example is shown by a reIatiw value. In the case
where this vdue is largex than 1, the transmission efficiencyy that is, the he1 saving
performance was judged as hi@.
4) Durability Running Test
The durability mmhg test was perfbrmed, as illustrated in Fig. 7, by wing a
biaxial running tester consisting of a Mve @r) pulley 62 having a dimdm of 50 mm stld
a driven (Dn.) pulley 63 having a diameter of 125 mm. A raw edge cogged V-belt 6 1 was
hung between respective pulleys 62and 63, the belt 61 was nm for maximally 60 hours at
an ambient temp- of 80°C by s&hg the rotation speed of the &ve pulley 62 at
5,000 rpm and applyhg a load of 10 N- m to the driven puIlcy 63. If the belt 61 ran for
60 hours, the durability was judged as having no problem. Mso, the cornpression rubbepside
sdace (the surface coming into owtact with the pulley) after d n n g was observed
with an eye, and the presence or absence of cracks was examined.
Results:
The physical properties of the vulcanized rubber and the physical pmpesties of the
belt are shown in Table 3.
[Table 31

As apparent from Table 3, in Examples, the strength at break (afilm parallel),
the stress at 100% elongation, the tiear strength and the elongation at break were high, the
transmission efficienoy @&-load running, high-speed running) and durability were high,
and the fuel saving perfo- was exctLI&, even without raising the hardness. Also,
even whm the W e s s is high, the strength at break srrd tear s?ren@h were hi& and the
transmission efficiency (high-load running, high-speed mmbg) and durability were high.
Grearer details are as follows.
1) Physical Pmperties of Vulcanized Rubber
From ExampIes 2 to 6, when the content of the f;lttv acid amide was increased,
reduction in the hardness was slightly abed, but no significant Merence was found.
In Example 7 and Comparative ExmpIe 2 where the contacts of short fiber and carbon
black were large, the hardness was tls very high as 94O. Fmm comparislon of Example 3
with Comparative Example 1, even when the fatty add amide was changed to a @c
acid, the hardness was not varied
From ExampIes 2 to 6, along with incrclase in the mount of the fatly acid amide,
the strength at break (sort fiber parallel), the stress at 100% elongation and the tear strength
tend to become higher. The reason therefor is consicked to be that the .fatty acid amide
and the adhesive component of the short fiber chemidy inba&ed and the adhesiveness
between the short fiber and the rubbet composition was tahand. In particular, the stress
at 1 00% elongation in the short fiber perpendicular dimdon where the eIastic modulus of
the short fiber is less likely to be reflected was hcreased, and this fact is considered to
support the above-described interaction, Also, Fram comparison of Example 3 with
Comparative Example 1, in the case of the fatty acid amide, all of the strength at break
(short fiber parallel, perpendicular), the stress at 100% elangatiun and the tear m g t h had
a high value, as compared with a &&c acid. The elongation at break ten& to decrease
dong with increase in the blending amount of a fatty mid d d e . The reamxi therefor is
considered to be that the adhesiveness between the short fiber md the rubber composition
was enhanced and the modulus became high.
Probably because the fhtty acid d d e 8ckd as an internd Iubricant and the matrix
rubber became flexible, it was observed that the compression stress and fhe bending sE.r.ess
tend to decrease along with increase in the momt of the fatty acid amida In Example 7
and Comparative Example 2 where the content af short fiber and carbon black large,
the compression stress and the bending stress were sigdfican'rzy increased.
2) Physical Properties of Belt
Since the fatty acid amide bloomed to the Surf= of the cornpres9ion rubber layer,
the friction coefficient tends to decrease along with increase in the amatlnt of the fatty acid
amide, but if exee&g a predetemhd mount (about 4 parts by mass of Exampie 4), no
great difference was found in the friction cmfficierrt.
h Examples 1 to 6, the ~ s s i oefnfici ency (high-1aad high-speed
running) was high and the fk1 saving pediommce was emdent, as compared with
Comparative Example 1. Also, as the blending mount of the fatty acid amide is larger,
the transmission eficiency: is higher,
In both of Example 7 and Comparative Example 2 whete the contents of shd
fiber and carbon black were large, a very high bending mss was exhibit4 but in
Comparative Example 2, the trammission efficiency was ~~ whmw in Example 7,
high transmission efficiency was exhibited.
In Examples 1 to 7, probably ls- the fatty acid amida bloomed to th surf3lce
of the compression rubber layer, the high-speed running property was enhanced, thc flying
out of the belt autward in the pulley radial diredon was smoothly effectmi, a d ?he pow&
transmission loss of the belt u9s reduced.
As fm the durability rum&, in Examples I to 7, a i k running for 60 horn, no
crack was generated in the compmsion rubber Iayer, idcat& high durabilxtyI On the
other hand, in Comparative Example I, separation occurred between the compressi~fi
rubber layer and the adhesive rubber layer and tbe Me expired in 25 hours; and in
Comparative Example 2, afta rtMning for 60 hours, because of large contents of short fik
and carbon black, the hardness was Mgh and the tear strength was low, as a mul6 a crack
was generated in the compression rubber layer.
Example 8 and Comparative Example 3:
In order to study the relationship among lhe fw acid amide, the stearic acid md
the kind of short fiber, physical properties ofthe vulimizcd mbhr were evaluated. An
untreated denim product (short fiber having a length of about 6 mm) was subjected to er
dipping treametlt in an RFL soIuticm wed in the above-described Example 1 for 10
minutes (the latex was a smne-bntadienevinylp*dine te?polpmer) and after removing
an excess RFL solution by centdfLgd sqaration, dried in a dry oven under the conditions
of 160°C for 1 hour to produce a mted denim product. The adhesion rate of an RFL
component in the tread denim product o W e d wd 13 mass%.
A rolled rubber sheet was produced in the same manner as in Exrunple 3 by using
the treated dcnim product @ereM€er, fratfed denixn) above and at the same time, using a
fatty acid amide in Example 8 or using astearic acid in place of a fatty acid amide in
Comparative Example 3. This rolled rubber sheet was press-vulcanized at a bemperatm
of I 6Q°C for a time of 20 mirutes to produce a M l l M rubber sheet (length: 100 mm,
width: 100 mm, thickness: 2 mm).
As physical properties of the v u l d e d rubber, tbe hardness, the stress at 100%
elongation, the strength at break, the elongation a! break, and the tear strength were
measured in the same manner as above. The results are shown in Table 4.
[Table 41
Table 4
1 I 1 i I
Example 8
Comparative
Example 5
Treated denim (parts by ma@ I 20
Fatty acid ami& (steatamide) ( p m by mass)
Stren ~ tStrehn -atbtpeak h ao r t e l I 11 16.1
From the Table, in the case of using atmated denim @kampIe 81, all of the
strength at break in the short fiber parallel direction aad the stress at 100% t1o~gation,
strength at break and tear strength in the short fiber perpendicular direotion had a hi@
value, and the elongation at b d was reduced, Also, as compared with a stcaric acid
(Comparative Example 31, in the case of using a fw acid amide (Example 81, dl of tbe
strength at break in tbe short fiber p d e l direction and the stress at 100% elongation,
strength at break and tear strength in tha short fiber perpendicular direction had a high
value, and the elongation at break: was f ow. Such a tendency was confinned also in ttre
case of an aramid short fiber above (comparison of Example 3 with Compdve Example
l), and it was revealed that the fiber species is irrelevant.
20
0
2
84
15.8
Sbess at 100% elongation (MPa)
Strength at break (MPa) ,
Elmgation at break (O/o)
Short film
9.9
13.1
9.2
11.6
250
pqxmdicuIar
238
Examples 9 and 10:
Vulcanized rubber sheets were produced in the same manner rrs in Example 3
except for using, ars fatty acid amides, a bisamide (ethyIen&isoldde ( m d fmula:
C3$72N202)r "SLIPACKS Ow, produced by Nippun Krrsei ChmicaI Co,, Ld, melting
point: 1 19°C) and an ester ami& (ethanolamine disteamte, "SLTAID Sn, produced by
Nippon Kasei Chemid Co., Ltd., melting point: 100°C). The measurement mfts of
physical properties of vulcanized rubber are sham in Table 5. Incidentally, tlm data of
Example 3 and Commve Example 1 are shown together for reference.
[Table 51
Table 5
In Ex8mpIes 3,9 and I0 using a fatty acid amide, as compared with Compdve
Example 1 using a s M c acid, rJI of the gtrength at break in the shod fiber parallel
direction and the stress at 100% elongation, strength at break and tear slnagth in the short
fiber perpendicular on had a high value9 md the elongation at break wrts reduced.
While the present invation has been described in detail and with reference to
specific embodiments hemof, it will be apparmt to one skilled in the art that various
Comparative
Example 1
20
0
h
hamid short fib (parts by mass)
Fatty acid amide (stmamide) (parts by: mass)
Fatty acid bisamide (ethylenebisoleamibe)
I
Example
10
20
0
3
20
2
9
20
0
changes and modifioatioas can be made thasin without departing fbm the spirit and scope
of the invention.
Tnis application is based on Japanese Paknt Application Na 201 1-1 13777 fded
on May 20,20 I I, tbe contents of which arc incoqora~edh erein by way ofr eferenm.
INDUSTIUAL APPLICABILITY
The power lm~smissionb elt of t?~pere sent itlwmtion tan be utiW as various
belts requiring reduction of the power trammission lass and is @&Iy for a fkiction
transmission belt. Tfie fiction fmnsmissian belt includes, for example, a raw edge belt
having a V-shaped cross-section, a raw edge cogged V-belt having cogs pmuided on the
inner circumferential side or both the inner Cipcumfmtial side and the outer
circumferential side of a raw edge belt, md a V-fibbed belt. In particulq it is p1xScrab1y
applied to a belt (variable speed belt) usused for a transmission where the gem ratio wries
continmusly during belt rum@.
DESCItlFTION OF REFERENCE lWJlW&US AND SIGNS
I : Adhesive rubber layer
2: Core wire
3: Compression rubber layer
4: Extensible rubber layer
M'e Claim:
1. A power tmmissim belt camprising rm adhesive rubber layer having a core wire
embedded therein in the longitudinal diredm of the belt, a oompmsim rubber layer
formed on one surface of the adhesive N b k layer, a d an extensible rubber layer formed
on another surface of said adhesive rubk kyer, whdn at laart said ooxnpssion rubba
Iayer contains a fatty acid amide and a short fiber.
2. The power transmission belt as claimed in claim 1, wbaein the short fiber
contains at least an adhesion-treated short fiber,
3. The power trammission belt as ciainid in claim I or .2, wherein the fatty acid
amide contains at least me member wlected from a m t e d or unsaturated lonig-chain
fatty acid amide and a saturated ax unsatumttd long-dwh fatty acid ester mi&.
4. The power transmission belt as claimed in any one af cIaims 1 to 3, wherein the
short fiber contains at least an aramid fiber.
5. The power transmission belt as claimed in any one of claims Z to 4, wherein the
rubber component of the compression rubber layer contains d o m e mbber, the f q
acid amide contains at Ieast a saturated or -ed fazty acid moxxodde having a
carbon number of 10 to 26 and an adhesive component con- at least amo~iann d
formalin initial condensate and a Satex is attached to the short f%al
6. The power transmission belt as claimed in my one of claims f to 5, wherein an
adhesive component containing a styrene-butadien8-vinylpyridine terpolymer is attaehed to
the short fiber.
7. The power transmission belt es claimed in any one of claims I to 6, wherein the
rubber composition constituting the cumpressian rubber layer contains hm 0.5 to 1 0 parts
by mass of the fatty acid d d e and hm 10 to 40 pwta by mass 01 the h r t fiber per 100
parts by mass of the raw material mbbercoqnmt,
8. A rubber composition for forming at least one rubber layer selected krn a
compression rubber 1a)w and an extensible rubber layer of a power trws&sion belt, the
rubber composition comprises a rubber component, a ktty mid amide and a short fibes.
9. The rubber cumposition as claimed in c 1 h 8, wherein the short fiber contains at
least an adhesion-treated short fiber.
10. A method for reducing power ~s~ loss by forming a compression rubber
layer of a power tnmdssion belt from Ebe rubber cornpasition claimed in claim 8 or 9.