Stock material or miscellaneous articles – Hollow or container type article – Glass – ceramic – or sintered – fused – fired – or calcined metal...
Reexamination Certificate
1994-04-01
2002-01-08
Clardy, S. Mark (Department: 1616)
Stock material or miscellaneous articles
Hollow or container type article
Glass, ceramic, or sintered, fused, fired, or calcined metal...
C428S034400, C428S034500, C428S034600, C428S035200, C428S035300, C428S035700, C428S035800, C428S036300, C428S036400, C428S036800, C428S036920, C428S208000, C428S208000, C428S208000, C428S208000, C428S208000, C428S299700, C428S109000, C428S114000, C428S035900, C162S358100, C162S358200, C162S358300, C162S358400, C162S358500
Reexamination Certificate
active
06337112
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an endless belt which can be used in a press apparatus such as an Extended Nip Press or Intensa S Press or the like for dewatering a wet web of paper in a paper making process.
2. Description of the Background Art
Recently, a so-called shoe press wherein, in the press part of a paper making process, dewatering of a web is carried out by pressing one surface of a web placed on a felt for enhancing the effect of dewatering the web with a rotary roll and pressurizing the other surface through an endless belt with a pressure shoe is becoming popular.
FIGS. 12
is a typical cross sectional view illustrating an Extended Nip Press as an example of such a press. Referring to
FIG. 12
, a pressure shoe
41
is arranged under a rotary roll
40
. An endless belt
42
as a dewatering press is provided between rotary roll
80
and pressure shoe
41
. Endless belt
42
is mounted and wound around guide rolls
43
a
and
43
b
and tension rolls
44
a
,
44
b
and
44
c
. A web
45
and felt
46
are passed between the endless belt
42
and the rotary roll
40
.
If the rotary roll
40
is rotated in a direction indicated by arrow A, web
45
placed on felt
46
and endless belt
42
are moved in directions indicated by arrow B and arrow C, respectively. Web
45
and felt
46
are pressed strongly toward the rotary roll
40
by the pressure shoe
41
in the range of the pressure dewatering part P. Accordingly, web
45
is dewatered in pressure dewatering part P.
FIG. 13
is a typical cross sectional view illustrating an Intensa S Press as another example. Referring to
FIG. 13
, a cylindrical endless belt
52
for a dewatering press is provided under a rotary roll
50
. A pressure shoe
51
pressing toward the rotary roll
50
.through endless belt
52
is provided inside the endless belt
52
. A web
54
and a felt
53
are passed between endless belt
52
and rotary roll
50
. A pressure dewatering part P having a large width is formed between rotary roll
50
and pressure shoe
51
. Web
54
is dewatered in pressure dewatering part P.
The following are endless belts for dewatering presses conventionally proposed for such shoe presses.
(1) a belt in which a synthetic resin such as polyurethane resin or rubber is impregnated into a base fabric of an endless belt from one of its surfaces (hereinafter referred to as a single coat type belt; U.K. Patent No. 2,106,555, U.K. Patent No. 2,106,557 and so forth)
(2) a belt in which an endless base fabric is embedded in a layer of synthetic resin or rubber (hereinafter referred to as a base fabric embedded belt: European Patent No. 194,602 and so forth)
(3) a belt in which a synthetic resin such as polyurethane resin or rubber is impregnated into an endless base fabric from both of its front and rear surfaces, and grooves are formed on the surface (hereinafter referred to as a double coat type grooved belt: U.S. Pat. Nos. 4,559,258, 4,908,103, 4,946,731 and so forth)
However, the above-described conventional endless belts for dewatering presses have problems as follows.
(a) Since all of the single coat type belt, the base fabric embedded belt, and the double coat type grooved belt use an endless base fabric impregnated with a synthetic resin or a rubber, the strength of the bond between the base fabric and the synthetic resin or rubber is small in such belts.
Particularly, in the case where layers disposed on both of the front and rear surfaces of the double coat type grooved belt are formed by the casting method, synthetic resin or rubber penetrates the base fabric from only one of the surfaces. Accordingly, it is not possible to cause the synthetic resin or rubber to penetrate the base fabric when the opposite surface is formed, so that a uniform anchoring effect from both sides cannot be obtained, and thus it is not possible to obtain a strong bond between the respective components. Therefore, there is the problem that, as the belt is used, a breaking away phenomenon is caused between the base fabric and the synthetic resin or the rubber which greatly reduces the life of the belt.
(b) An endless base fabric is normally formed of monofilaments such as polyamide fiber, polyester fiber, or the like. Such fiber is generally a material having hardness higher than the hardness of the synthetic resin or rubber. Therefore, when the endless base fabric is bent during the conveying of the belt, the endless base fabric tends to be subject to a concentration of stress, and a breaking away phenomenon tends to occur between the base fabric and the synthetic resin or the rubber. The life of the conventional belt is also made relatively short for this reason.
(c) Since the double coat type grooved belt is provided with grooves on its surface, moisture generated by dewatering of a web is held in the grooves. Therefore, the double coat type grooved belt has superior dewatering efficiency as compared with the single coat type belt. However, the double coat type grooved belt is formed on both its front and rear surfaces by the casting method or the like using a synthetic resin or a rubber. When one surface is formed after formation of the other surface, the texture of the base fabric is already tight, so that bubbles in the coating material do not disappear easily, and the belt is formed with the bubbles remaining. Accordingly, in the case of the double coat type grooved belt, such bubbles tend to be left in the resin or the rubber. If such a belt is used, white water which is pressurization during pressurizing of a rotary roll permeates from the bottom part of the grooves into the bubbles and further permeates from the bubbles into the base fabric. As a result, the breaking away phenomenon between the base fabric and a coating layer occurs at a relatively early time which shorten the life of the belt.
(d) In addition, the conventional endless belts use endless base fabric. The tensile force of filaments in endless base fabric is often not uniform, and it often happens that the base fabric is distorted in the belt during a manufacturing process thereof. Therefore, the entire belt tends to receive the distortion and is correspondingly deformed, or wrinkles or the like tend to be generated.
SUMMARY OF THE INVENTION
An object of the present invention is to solve such conventional problems and provide an enduring endless belt for a dewatering press in which no breakdown such as the breaking away phenomenon occurs and which can be used stably for a long time.
An endless belt according to the present invention is characterized in that a fibrous me is dispersed in a substantially uniform manner throughout a cylindrical endless elastic body layer.
According to the present invention, a cylindrical endless elastic body layer can be formed by impregnating a liquid elastic body precursor into a fibrous material and curing the liquid elastic body precursor.
Non-woven fabric may be used, for example, as the fibrous material to be impregnated with the liquid elastic body precursor. Non-woven fabric is natural fiber, chemical fiber, glass fiber, metallic fiber, or the like coupled by a chemical or physical method. Such non-woven fabric includes stitch bond non-woven fabric, needle punched non-woven fabric, spun bond non-woven fabric, melt blown non-woven fabric, spun lace non-woven fabric, wet laid process non-woven fabric, chemical bond type dry laid process non-woven fabric, thermal bond type dry laid process non-woven fabric, or air laid type dry laid process non-woven fabric and wet laid process non-woven fabric, or the like.
An organic fiber and/or an inorganic fiber is used as the material for a non-woven tape. Polyamide fiber, aromatic polyamide fiber, polyester fiber, polyacrylonitrile fiber, polyvinyl alcohol fiber, polyethylene fiber, polypropylene fiber, polyurethane fiber, polyvinyl chloride fiber, polystyrene fiber, polyfluoroethylene fiber, regenerated cellulose fiber, cotton fiber, or the like is used as the organic fiber.
Glass fiber, metallic fiber, rock fiber, or the like is used
Hikida Takahisa
Nakayama Kenjiro
Watanabe Atsuo
Birch & Stewart Kolasch & Birch, LLP
Clardy S. Mark
Williamson Michael A.
Yamauchi Corporation
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