U.S. patent application number 11/791051 was filed with the patent office on 2008-07-10 for reinforcing sheet for reinforcing toothed belt,and toothed belt and method for production thereof.
This patent application is currently assigned to NIPPON SHEET GLASS COMPANY, LIMITED. Invention is credited to Mitsuharu Akiyama, Naoya Mizukoshi.
Application Number | 20080166576 11/791051 |
Document ID | / |
Family ID | 36407101 |
Filed Date | 2008-07-10 |
United States Patent
Application |
20080166576 |
Kind Code |
A1 |
Akiyama; Mitsuharu ; et
al. |
July 10, 2008 |
Reinforcing Sheet for Reinforcing Toothed Belt,and Toothed Belt and
Method for Production Thereof
Abstract
A method of manufacturing of the present invention is a method
of manufacturing a toothed belt (10) having a belt part (13) and a
tooth part (14) sticking out of the belt part (13). This method of
manufacturing includes a first step of forming a reinforcing-sheet
(12) including a fiber sheet and a coating film formed on the fiber
sheet by drying the fiber sheet on which an aqueous treatment agent
containing a first rubber latex and a first vulcanizing agent is
applied, and a second step of reinforcing a surface of the tooth
part (14) with the reinforcing-sheet (12) by vulcanizing the first
rubber and a second rubber at the same time while adhering a rubber
composition, which is a material for the tooth part (14), including
the second rubber and a second vulcanizing agent to the
reinforcing-sheet (12). The aqueous treatment agent contains the
vulcanizing agent in the range of 10 parts by weight to 100 parts
by weight for 100 parts by weight of the first rubber.
Inventors: |
Akiyama; Mitsuharu; (Tokyo,
JP) ; Mizukoshi; Naoya; (St. Helens, GB) |
Correspondence
Address: |
HAMRE, SCHUMANN, MUELLER & LARSON, P.C.
P.O. BOX 2902
MINNEAPOLIS
MN
55402-0902
US
|
Assignee: |
NIPPON SHEET GLASS COMPANY,
LIMITED
Tokyo
JP
|
Family ID: |
36407101 |
Appl. No.: |
11/791051 |
Filed: |
November 15, 2005 |
PCT Filed: |
November 15, 2005 |
PCT NO: |
PCT/JP05/20965 |
371 Date: |
August 10, 2007 |
Current U.S.
Class: |
428/500 ;
156/307.5 |
Current CPC
Class: |
B29D 29/08 20130101;
B32B 2305/08 20130101; D06N 3/10 20130101; F16G 1/28 20130101; B32B
25/10 20130101; B32B 2413/00 20130101; B32B 2038/0076 20130101;
D06N 3/0056 20130101; B32B 2264/108 20130101; Y10T 428/31855
20150401; B32B 25/14 20130101; D06M 15/693 20130101 |
Class at
Publication: |
428/500 ;
156/307.5 |
International
Class: |
B32B 27/12 20060101
B32B027/12; C08J 5/18 20060101 C08J005/18 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 19, 2004 |
JP |
2004-336603 |
Claims
1. A reinforcing-sheet for reinforcing a toothed belt comprising: a
fiber sheet; and a coating film formed on the fiber sheet, wherein
the coating film is formed by drying the fiber sheet on which an
aqueous treatment agent containing a rubber latex and a vulcanizing
agent as its main components is applied, the aqueous treatment
agent contains the vulcanizing agent in the range of 30 parts by
weight to 75 parts by weight for 100 parts by weight of the rubber,
and the vulcanizing agent is at least one vulcanizing agent
selected from a group consisting of a maleimide vulcanizing agent,
organic diisocyanate and an aromatic nitroso-compound.
2. The reinforcing-sheet according to claim 1, wherein the aqueous
treatment agent further contains carbon black.
3. A method of manufacturing a toothed belt having a belt part and
a tooth part sticking out of the belt part, comprising: a first
step of forming a reinforcing-sheet including a fiber sheet and a
coating film formed on the fiber sheet by drying the fiber sheet on
which an aqueous treatment agent containing a first rubber latex
and a first vulcanizing agent is applied; and a second step of
reinforcing a surface of the tooth part with the reinforcing-sheet
by vulcanizing the first rubber and a second rubber at the same
time while adhering a rubber composition, which is a material for
the tooth part, including the second rubber and a second
vulcanizing agent to the reinforcing-sheet, wherein the aqueous
treatment agent contains the first vulcanizing agent in the range
of 30 parts by weight to 75 parts by weight for 100 parts by weight
of the first rubber, and the first vulcanizing agent is at least
one vulcanizing agent selected from a group consisting of a
maleimide vulcanizing agent, organic diisocyanate and an aromatic
nitroso-compound.
4. The method of manufacturing a toothed belt according to claim 3,
wherein the aqueous treatment agent further contains carbon
black.
5. (canceled)
6. The method of manufacturing a toothed belt according to claim 3,
wherein the first vulcanizing agent is
diphenylmethane-4,4'-bismaleimide.
7. The method of manufacturing a toothed belt according to claim 3,
wherein the first rubber is at least one rubber selected from
nitrile rubber and hydrogenated nitrile rubber.
8. The method of manufacturing a toothed belt according to claim 3,
wherein the first rubber is a carboxylated rubber.
9. A toothed belt manufactured by the method of manufacturing
according to claim 3.
Description
TECHNICAL FIELD
[0001] The present invention relates to a reinforcing-sheet for
reinforcing a toothed belt, to a toothed belt and to a method of
manufacturing the same.
BACKGROUND ART
[0002] In order to improve durability and fraying resistance of
toothed belts, it has been commonly practiced to bury fibers known
as tooth sheet into a surface of their tooth parts. By using a
tooth sheet, the durability of tooth parts and the fraying
resistance of the rubber surface are improved. Fibers woven in a
form of a sheet are generally employed as such a tooth sheet. A
surface of the tooth sheet is generally processed by various
treatment agents for enhancing adhesion of the belt body with its
rubber matrix. As an example, a tooth sheet impregnated with rubber
cement including a filler, such as carbon, after processing with a
liquid mixture of a condensate of resorcinol and formaldehyde and
latex is disclosed in JP7(1995)-217705A. As another example, a
tooth sheet processed with a rubber composition obtained by mixing
N,N'-m-phenylene dimaleimide into hydrogenated nitrile rubber is
disclosed in JP7(1995)-259928A.
[0003] While adhesion under a static test of the conventional tooth
sheets processed with the treatment agents is relatively high, the
conventional tooth sheets easily crack between themselves and cords
or rubber matrixes due to their poor integration with the belt
parts when run for many hours as a belt. As a result, troubles were
prone to arise, such as chipping in the tooth part. In addition, it
was necessary to protect the environment during the manufacturing
processes when a tooth sheets is treated with a conventional
treatment agent using an organic solvent.
DISCLOSURE OF INVENTION
[0004] With such a situation in mind, one of the objects of the
present invention is to provide a reinforcing-sheet for reinforcing
a toothed belt capable of forming a toothed belt that is easy to
manufacture and has less fracture in a tooth part even when used
for many hours. Furthermore, other objects of the present invention
are to provide a toothed belt using a reinforcing-sheet for a
toothed belt according to the present invention and to provide a
method of manufacturing the same.
[0005] In order to achieve the above-mentioned objects, the
reinforcing-sheet of the present invention is a reinforcing-sheet
for reinforcing a toothed belt that includes a fiber sheet and a
coating film formed on the fiber sheet. The coating film is formed
by drying the fiber sheet on which an aqueous treatment agent
containing a rubber latex and a vulcanizing agent as its main
components is applied. The aqueous treatment agent contains the
vulcanizing agent in the range of 10 parts by weight to 100 parts
by weight for 100 parts by weight of the rubber.
[0006] The method for manufacturing a toothed belt of the present
invention is a method of manufacturing a toothed belt that has a
belt part and a tooth part sticking out of the belt part. The
method of the present invention includes a first step of forming a
reinforcing-sheet including a fiber sheet and a coating film formed
on the fiber sheet by drying the fiber sheet on which an aqueous
treatment agent containing a first rubber latex and a first
vulcanizing agent is applied; and a second step of reinforcing a
surface of the tooth part with the reinforcing-sheet by vulcanizing
the first rubber and a second rubber at the same time while
adhering a rubber composition, which is a material for the tooth
part, including a second rubber and a second vulcanizing agent to
the reinforcing-sheet. The aqueous treatment agent contains the
vulcanizing agent in the range of 10 parts by weight to 100 parts
by weight for 100 parts by weight of the first rubber.
[0007] The toothed belt of the present invention is a toothed belt
manufactured by the method of manufacturing of the present
invention described above.
[0008] According to the present invention, a reinforcing-sheet
capable of forming a toothed belt having excellent heat resistance
and bending fatigue resistance can be obtained. Since the aqueous
treatment agent employed for the reinforcing-sheet does not
generally contain substances having a heavy environmental load,
such as an organic solvent, formaldehyde and ammonia, a working
environment during the coating film forming step is favorable.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a cross-sectional view that schematically shows an
example of a toothed belt manufactured by the manufacturing method
of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0010] Hereinafter, embodiments of the present invention are
described in detail.
[Reinforcing-Sheet for a Toothed Belt]
[0011] A reinforcing-sheet (a tooth sheet) for a toothed belt of
the present invention includes a fiber sheet and a coating film
formed on the fiber sheet. The coating film is formed by drying the
fiber sheet on which an aqueous treatment agent (an aqueous
adhesive) containing a rubber (hereinafter, also referred to as a
"first rubber") latex and a vulcanizing agent as its main
components is applied. The aqueous treatment agent contains the
vulcanizing agent in the range of 10 parts by weight to 100 parts
by weight for 100 parts by weight of the first rubber (of solid
content).
[0012] It is preferable that the aqueous treatment agent further
contains carbon black. Adding carbon black enables cost reduction
for manufacturing a reinforcing-sheet. Since carbon black enables
enhancing cohesion of the coating component, heat resisting
adhesion of a reinforcing-sheet and a tooth rubber can be enhanced
effectively. Although an organic/inorganic filler, such as silica
and talc, other than carbon black may be blended, carbon black is
still preferable from the perspective of its reinforcing effect and
its stability.
[0013] The aqueous treatment agent contains the first rubber latex
and the vulcanizing agent as its main components. That is, the
first rubber (solid content) and the vulcanizing agent are, in
total, 50 wt. % or more (for example, 70 wt. % or more) of the
whole components (other than the solvent and the dispersion medium)
of the aqueous treatment agent.
[0014] Examples of the vulcanizing agent may include the following
agents: quinone dioxime vulcanizing agents, such as
p-quinonedioxime; methacrylate vulcanizing agents, such as lauryl
methacrylate and methyl methacrylate; allyl vulcanizing agents,
such as DAF (diallyl fumarate), DAP (diallyl phthalate), TAC
(triallylcyanurate), and TAIC (triallyl isocyanurate); maleimide
vulcanizing agents, such as bismaleimide, phenyl maleimide, and
diphenylmethane-4,4'-bismaleimide (N,N'(4,4'-diphenylmethane)
bismaleimide); aromatic or aliphatic organic diisocyanate; aromatic
nitroso compound and sulfur. These vulcanizing agents may be
employed alone or in combination of a plurality of them. The
vulcanizing agents are selected in consideration of conditions,
such as the type of rubber.
[0015] Among them, it is preferred to employ at least one
vulcanizing agent selected from maleimide vulcanizing agents,
organic diisocyanate and aromatic nitroso compound. By employing
them, the adhesion of the reinforcing-sheet and the rubber matrix
specifically can be enhanced. In particular,
diphenylmethane-4,4'-bismaleimide is excellent in stability when
dispersed in water, cross-linking effect and heat resistance after
vulcanization.
[0016] Examples of the first rubber latex included in the aqueous
treatment agent may include the following latexes:
butadiene-styrene copolymer latex, dicarboxylated butadiene-styrene
copolymer latex, vinylpyridine-butadiene-styrene terpolymer latex,
chloroprene latex, butadiene rubber latex, chlorosulfonated
polyethylene latex, nitrile rubber latex (acrylonitrile-butadiene
copolymer latex) and hydrogenated nitrile rubber latex. These
rubber latexes may be employed alone or in combination.
[0017] Among them, it is preferred to employ at least one rubber
selected from nitrile rubber and hydrogenated nitrile rubber as the
first rubber. These rubbers are excellent in heat resisting
adhesion and fraying resistance. When hydrogenated nitrile rubber
is employed for the rubber matrix, compatibility of the coating
film and the rubber matrix is improved by employing hydrogenated
nitrile rubber latex.
[0018] The first rubber may be a carboxylated rubber. By employing
the carboxylated rubber, its adhesion can be enhanced further. The
carboxylated rubber is not particularly limited, and a rubber
obtained by carboxylated of any rubber mentioned above may be
employed, for example.
[0019] The aqueous treatment agent may include other substances,
such as a peroxide, a plasticizer, an antioxidant, a metal oxide
and a stabilizer.
[0020] The components mentioned above are dispersed or dissolved in
an aqueous solvent of the aqueous treatment agent. An aqueous
solvent has an excellent handling property and enables easy control
of the concentrations of the components. In addition, it remarkably
reduces the environmental load compared to an organic solvent. The
aqueous solvent contains water as its main component (50 wt. % or
more, preferably 65 wt. % or more), and an example of such an
aqueous solvent is made of water alone substantially. The aqueous
solvent may contain lower alcohol. It is preferable that the
aqueous solvent does not substantially contain formaldehyde,
ammonia and organic solvent other than lower alcohol.
[0021] The aqueous treatment agent contains the vulcanizing agent
in the proportions of 10 parts by weight to 100 parts by weight for
100 parts by weight of the first rubber. In this case, it is
preferable that the aqueous treatment agent contains carbon black
in the proportions of 5 parts by weight to 70 parts by weight for
100 parts by weight of the first rubber. The aqueous treatment
agent preferably contains the vulcanizing agent in the range of 20
parts by weight to 75 parts by weight for 100 parts by weight of
the first rubber, and further preferably contains it in the range
of 30 parts by weight to 75 parts by weight. By using such an
aqueous treatment agent, a high adhesion can be obtained even with
a single layer coating film. In such a case, it is preferable that
the aqueous treatment agent contains carbon black in the range of
10 parts by weight to 30 parts by weight for 100 parts by weight of
the first rubber.
[0022] The relationship between the amounts of rubber and
vulcanizing agent in the aqueous treatment agent is particularly
important. The vulcanizing agent in the treatment agent is spread
into the rubber matrix when vulcanizing both the first rubber and
the rubber matrix, which enables the reinforcement of the
vulcanization of not only the coating film but also the rubber
matrix. As a result, excellent adhesion strength and integration
can be obtained. When the amount of vulcanizing agent is too
little, the coating film itself can be vulcanized to some extent,
but the reinforcing effect of the rubber matrix cannot be obtained.
The integration of the reinforcing-sheet and the rubber matrix
becomes insufficient, accordingly, and a sufficient adhesion
strength cannot be obtained. On the other hand, when the amount of
vulcanizing agent is too much, the coating film increases its
degree of hardness, and it leads to a decrease in strength of the
toothed belt when the belt is bent.
[0023] Examples of a preferable combination of the first rubber and
the vulcanizing agent may include a hydrogenated nitrile rubber
with a maleimide vulcanizing agent, a carboxylated nitrile rubber
with a maleimide vulcanizing agent and a carboxylated hydrogenated
nitrile rubber with a maleimide vulcanizing agent. Employing such
combination enables particularly the adhesion of the
reinforcing-sheet with the rubber matrix to be enhanced.
[0024] The fiber sheet is a sheet constituted by reinforcing
fibers. The reinforcing fibers are not particularly limited as long
as they enhance shape stability and strength of the
reinforcing-sheet. For example, glass fibers; polyvinyl alcohol
fibers, such as vinylon fibers; polyester fibers; polyamide fibers,
such as nylon and aramid (aromatic polyamide) fibers; carbon fibers
and polyparaphenylene benzoxazole (PBO) fibers may be employed. A
preferable example of the fiber sheet is made of nylon fibers
knitted in a form of a sheet. These fibers may be employed alone or
in combination of a plurality of them. The fiber sheet is not
limited in its form as long as it keeps a form of a sheet, and it
may be either a woven or a nonwoven sheet.
[0025] The coating film on the fiber sheet includes an unvulcanized
rubber and a vulcanizing agent. The amount of coating film is not
particularly limited, and an example of the proportions of coating
film occupied in the whole reinforcing-sheet may be in a range of 5
wt. % to 30 wt. %, such as 6 wt. % to 15 wt. %.
[0026] The reinforcing-sheet of the present invention includes a
coating film covering a fiber sheet, and the coating film contains
a vulcanizing agent in high proportion. When the reinforcing-sheet
and a rubber matrix of a toothed belt are integrated, the
vulcanizing agent enhances integration of the reinforcing-sheet and
the rubber matrix by being spread into the rubber matrix. Thus,
according to the reinforcing-sheet of the present invention, a
toothed belt having less fracture in the tooth part under many
hours of use can be obtained. In addition, since a treatment agent
employed for manufacturing this reinforcing-sheet includes an
aqueous solvent, the environmental load is small and the handling
property during manufacture is facilitated. The reinforcing-sheet
of the present invention is easy to manufacture because the coating
film is normally a single layer. A method of manufacturing the
reinforcing-sheet is described below.
[Method of Manufacturing a Toothed Belt]
[0027] A manufacturing method of the present invention is a method
of manufacturing a toothed belt having a belt part and a tooth part
sticking out of the belt part. A toothed belt manufactured by this
manufacturing method is a toothed belt of the present
invention.
[0028] This manufacturing method includes a step (a first step) of
forming a reinforcing-sheet including a fiber sheet and a coating
film formed on the fiber sheet by drying the fiber sheet on which
an aqueous treatment agent containing a first rubber latex and a
first vulcanizing agent is applied. The reinforcing-sheet of the
present invention can be obtained by this step. The materials, such
as the fiber sheet and the aqueous treatment agent, and the
proportions of materials are as described above and the overlapping
description is omitted. For instance, the vulcanizing agents
mentioned above may be employed for the first vulcanizing
agent.
[0029] The method of forming the coating film is not particularly
limited. For example, the coating film may be formed by immersing
the fiber sheet in a container with the aqueous treatment agent and
drawing up the fiber sheet from the container, and removing the
solvent through a drying furnace. The method of drying is not
particularly limited, and drying by heating may be applied, for
example. In the first step, however, the fiber sheet is dried under
the condition that restrains the vulcanization of the first rubber
in the aqueous treatment agent from progressing. For example, the
fiber sheet may be dried by exposing it to an atmosphere at a
temperature in the range of 80.degree. C. to 160.degree. C. for 0.1
minute to 2 minutes. The coating film formed in the first step
includes a vulcanizing agent and an unvulcanized rubber or a rubber
vulcanized insufficiently.
[0030] Next, a surface of the tooth part is reinforced with the
reinforcing-sheet vulcanizing the first rubber and a second rubber
(a rubber in a rubber composition) at the same time while adhering
the rubber composition, which is a material for the tooth part, to
the reinforcing-sheet (a second step). The rubber composition
contains a second rubber and a second vulcanizing agent as its main
components. The drying condition during the vulcanization is
selected according to the type and the amount of rubber and
vulcanizing agent. In the second step, generally, the first rubber
and the second rubber are heated for vulcanization while the rubber
composition, which is a material for the belt body (the belt part
and the tooth part), is adhered to the reinforcing-sheet. The
rubber composition may be formed in a predetermined shape either
before or after the vulcanization.
[0031] The second rubber (the rubber matrix) is selected according
to the property required for the toothed belt. The rubbers
mentioned as the first rubber may be applied for the second rubber,
for example. Although the first and the second rubbers may be
either the same or different, the integration of the
reinforcing-sheet with the belt body can be enhanced by employing
the same rubber for both of them. The rubber composition is either
an unvulcanized rubber or a rubber vulcanized incompletely, and
contains an additive, such as a vulcanizing agent. The vulcanizing
agent is not particularly limited, and the vulcanizing agents
mentioned above and known vulcanizing agents may be applied.
[0032] The reinforcing-sheet generally is disposed to cover the
entire surface side of the belt body (the belt part and the tooth
part) on which the tooth part is formed, i.e. a surface of the
tooth part (a convex part) and a surface of the concave part on
which the tooth part is not formed, and reinforces those surfaces.
A method of integrating the reinforcing-sheet and the toothed belt
is not particularly limited, and a known method may be applied. An
example of such a method may be a method in which the
reinforcing-sheet, a reinforcing cord and a sheet of rubber
composition as the material for the belt body are wound in this
order on a cylindrical mold on which a concave part is formed at a
position according to the tooth part, and then subjected to heat
and pressure from the outside. In this method, the tooth part and
the belt part are formed by forming the sheet of rubber
composition, and then the reinforcing-sheet is disposed on their
surfaces. The first and the second rubbers are vulcanized at the
same time when heat and pressure are applied. Some modifications
may be allowed, such as disposing another reinforcing-sheet on the
surface of the other side from the tooth part, forming the sheet of
rubber composition in bi-layer structure or further interposing
another reinforcing-sheet in the bi-layer structure.
[0033] A cross-sectional view of an example of the toothed belt
manufactured by the manufacturing method of the present invention
is schematically shown in FIG. 1. A toothed belt 10 in FIG. 1
includes a belt body 11 and a reinforcing-sheet 12. The belt body
11 includes a belt part 13 and a plurality of tooth parts 14, which
stick out of the belt part 13 at regular intervals. The
reinforcing-sheet 12 is disposed to cover one of surfaces of the
belt body 11 on which the tooth parts 14 are formed. The belt part
13 has a reinforcing cord 15 buried therein. A strand covered by a
coating film including rubber may be used for the reinforcing cord
15, for example. The strand may be formed with reinforcing fibers,
such as glass fibers and resin fibers. The coating film of the
reinforcing cord 15 may be formed with the aqueous adhesive
described above, for example. The rubber in the coating film of the
reinforcing cord 15 preferably is vulcanized at the same time with
the first rubber and the rubber matrix.
[0034] Since both the first rubber of the reinforcing-sheet and the
second rubber constituting the tooth part are vulcanized at the
same time in the manufacturing method of the present invention, it
becomes possible to enhance the integration of the
reinforcing-sheet with the belt body dramatically. Because the
vulcanizing agent included in the coating film of the
reinforcing-sheet is spread into the second rubber in this method,
the integration of the reinforcing-sheet with the belt body
particularly can be enhanced. This effect is enhanced particularly
when the aqueous treatment agent contains the vulcanizing agent in
the range of 30 parts by weight to 75 parts by weight for 100 parts
by weight of the first rubber.
[0035] According to the method of the present invention, a toothed
belt having excellent heat resistance, integration under many hours
of use and bending fatigue resistance can be obtained.
EXAMPLES
[0036] Hereinafter, the present invention is described further
using examples.
Example 1
[0037] A reinforcing-sheet for a toothed belt was formed by
applying an aqueous treatment agent indicated in (1) of Table 1 on
nylon fibers knitted in a sheet and then by drying at a temperature
of 120.degree. C. for one minute.
TABLE-US-00001 TABLE 1 Weight Ratio of Solid Content Components (1)
(2) (3) (4) Hydrogenated Nitrile Rubber Latex (*1) 100 100 100
Nitrile Rubber Latex (*2) 100 Carbon Black 20 20 20 20 Vulcanizing
Diphenylmethane-4,4'-bismaleimide 50 50 Agent Organic Diisocyanate
(*3) 50 Aromatic Nitroso-Compound 50 Total 170 170 170 170 (*1)
Carboxylated Hydrogenated Nitrile Rubber Latex, manufactured by
ZEON Corporation (*2) High Acrylonitrile-Butadiene Copolymer Latex,
manufactured by ZEON Corporation (*3) Hexamethylene
Diisocyanate
[0038] Meanwhile, a reinforcing cord was formed by processing glass
fibers with an RFL treatment liquid in (2) of Table 2, i.e. a
mixture of a resorcinol-formaldehyde condensate and hydrogenated
nitrile rubber latex. The reinforcing-sheet and the reinforcing
cord were heat treated with a rubber composition (rubber matrix)
having a composition indicated in Table 3 at a temperature of
170.degree. C. for 30 minute in order to vulcanize the rubber of
the reinforcing-sheet and the rubber matrix at the same time.
TABLE-US-00002 TABLE 2 Weight Ratio of Solid Content Components (1)
(2) Hydrogenated Nitrile Rubber Latex (*1) 100 100 Carbon Black 20
Vulcanizing Agent 5 (Diphenylmethane-4,4'-bismaleimide)
Resorcinol-Formaldehyde Condensate 9 Total 125 109 (*1)
Carboxylated Hydrogenated Nitrile Rubber Latex, manufactured by
ZEON Corporation
TABLE-US-00003 TABLE 3 Components Weight Ratio H-NBR (*4) 70
H-NBR/ZDMA (*5) 30 ZnO 10 Stearic Acid 1 Carbon Black 30 TOTM 5
(Trioctyl Trimellitate) Sulfur 0.1
1,3-Bis-(t-butylperoxy-isopropyl)-benzene 6 Total 152.1 (*4)
Hydrogenated Nitrile Rubber (manufactured by ZEON Corporation:
ZETPOL 2020 (trade name)) (*5) Hydrogenated Nitrile Rubber
including Zinc Dimethacrylate (manufactured by ZEON Corporation:
ZSC 2000L (trade name))
[0039] A toothed belt having a reinforcing-sheet disposed on the
surface of the side of tooth part and a reinforcing cord buried in
the belt part was manufactured in the manner described above.
Example 2
[0040] Another toothed belt was fabricated under the same condition
as Example 1 except for employing an aqueous treatment agent
indicated in (2) of Table 1 instead of the aqueous treatment agent
of (1) of Table 1.
Example 3
[0041] Another toothed belt was fabricated under the same condition
as example 1 except for employing an aqueous treatment agent
indicated in (3) of Table 1 instead of the aqueous treatment agent
of (1) of Table 1.
Example 4
[0042] Another toothed belt was fabricated under the same condition
as Example 1 except for employing an aqueous treatment agent
indicated in (4) of Table 1 instead of the aqueous treatment agent
of (1) of Table 1.
Example 5
[0043] An aqueous treatment agent that is the same as the aqueous
treatment agent of (1) of Table 1, except for employing
hydrogenated nitrile rubber latex that is not carboxylated instead
of carboxylated hydrogenated nitrile rubber latex, was prepared.
Another toothed belt was fabricated under the same condition as
Example 1 except for employing this aqueous treatment agent instead
of the aqueous treatment agent of (1) of Table 1.
Comparative Example 1
[0044] Another toothed belt was fabricated under the same condition
as Example 1 except for employing an aqueous treatment agent
indicated in (1) of Table 2 instead of the aqueous treatment agent
of (1) of Table 1.
Comparative Example 2
[0045] Another toothed belt was fabricated under the same condition
as Example 1 except for employing an RFL treatment liquid indicated
in (2) of Table 2 instead of the aqueous treatment agent of (1) of
Table 1.
[0046] For the toothed belts of the Examples and Comparative
Examples, the peel strength of the reinforcing-sheet and the rubber
matrix was tested to measure the adhesion strength between them and
to observe each fracture type. In addition, bending run properties
of these toothed belts were tested under an atmosphere at a
temperature of 140.degree. C. for 100 hours to check the presence
of peeling on the reinforcing-sheets after running. Moreover, the
strength of the toothed belts before and after the running test was
measured to calculate the proportion of strength before the running
test to strength after the running test, i.e. the strength
retention rate. Results of the evaluation are shown in Table 4.
TABLE-US-00004 TABLE 4 Comparative Examples Examples 1 2 3 4 5 1 2
Adhesion 450 390 330 480 320 200 30 Strength [N/19 mm] Fracture
Rubber Rubber Rubber Rubber Rubber Partial Interfacial Type
Fracture Fracture Fracture Fracture Fracture Rubber Peeling
Fracture Crack Not Not Not Not Not Found Found after the Found
Found Found Found Found Running Test Strength 80 75 70 71 70 60 30
Retention (%)
[0047] As shown in Table 4, the toothed belts of Examples were
higher in their adhesion strength of the reinforcing-sheet and
rubber matrix than those of Comparative Examples. In addition, no
crack was found in the toothed belts of the Examples after the
running test, and they showed higher strength retention than those
of the Comparative Examples. Moreover, the adhesion strength of the
reinforcing-sheet and the rubber matrix was particularly high when
the carboxylated rubber latex was employed.
[0048] The present invention is applicable to other embodiments as
long as they do not depart from the intention and essential
characteristics thereof. The embodiments disclosed in this
specification are to be considered in all respects as illustrative
and not limiting. The scope of the present invention is indicated
by the appended claims rather than by the foregoing description,
and all changes that come within the meaning and range of
equivalency of the claims are intended to be embraced therein.
INDUSTRIAL APPLICABILITY
[0049] The present invention is applicable to a reinforcing-sheet
for a toothed belt, to a toothed belt and to a method of
manufacturing the same.
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