U.S. patent application number 11/273262 was filed with the patent office on 2006-06-08 for shoe press belt.
This patent application is currently assigned to Ichikawa Co., Ltd.. Invention is credited to Jun Ishino, Hiroyuki Takamura.
Application Number | 20060118261 11/273262 |
Document ID | / |
Family ID | 36572897 |
Filed Date | 2006-06-08 |
United States Patent
Application |
20060118261 |
Kind Code |
A1 |
Ishino; Jun ; et
al. |
June 8, 2006 |
Shoe press belt
Abstract
To provide a shoe press belt that is more excellent in the
properties such as abrasion resistance, bending fatigue, crack
resistance, and compression fatigue resistance. The shoe press belt
has polyurethane and a substrate, wherein the polyurethane contains
a non-reactive polydimethylsiloxane liquid substance and has a JIS
A hardness of 93.degree. to 96.degree..
Inventors: |
Ishino; Jun; (Tokyo, JP)
; Takamura; Hiroyuki; (Tokyo, JP) |
Correspondence
Address: |
MORGAN LEWIS & BOCKIUS LLP
1111 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20004
US
|
Assignee: |
Ichikawa Co., Ltd.
|
Family ID: |
36572897 |
Appl. No.: |
11/273262 |
Filed: |
November 15, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60637463 |
Dec 21, 2004 |
|
|
|
Current U.S.
Class: |
162/358.4 ;
162/901 |
Current CPC
Class: |
D21F 3/0227
20130101 |
Class at
Publication: |
162/358.4 ;
162/901 |
International
Class: |
D21F 3/00 20060101
D21F003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 16, 2004 |
JP |
2004-332179 |
Claims
1. A shoe press belt comprising polyurethane and a substrate,
wherein said polyurethane contains a non-reactive
polydimethylsiloxane liquid substance and has a JIS A hardness of
93.degree. to 96.degree..
2. The shoe press belt according to claim 1, wherein said
polyurethane is a mixture of polyurethane having a JISA hardness of
90.degree. to 93.degree. and containing a non-reactive
polydiluethylsiloxane liquid substance, and polyurethane having a
JIS A hardness of 98.degree. and not containing a non-reactive
polydimethylsiloxane liquid substance.
Description
[0001] This application claims the benefit of U.S. Provisional
Application No. 60/637,463, filed Dec. 21, 2004, which is hereby
incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a shoe press belt useful
for a paper shoe press, and particularly to a shoe press belt
useful for a shoe press of closed type. More particularly, the
invention relates to a shoe press belt having the resin layers
composed of polyurethane having a specific composition and
hardness, and having excellent physical properties of crack
resistance, abrasion resistance, and bending fatigue
resistance.
[0004] 2. Description of the Background Art
[0005] In a shoe press process, a shoe press mechanism 100
comprising a looped shoe press belt 1 interposed between a press
roll 101 and a shoe 102 is employed, a wet paper (not shown) is
passed between the press roll 101 and the shoe press belt 1 in a
press portion formed by the press roll 101 and the shoe 102 to make
dehydration, as shown in FIG. 1.
[0006] Also, the shoe press belt 1 has the resin layers 5, 6
integrally provided on both sides of a substrate 3, and many
concave grooves 7 are formed on the surface of a resin layer 5 on
the press roll side, as shown in a cross-sectional view of FIG. 2.
Water squeezed from a wet paper at the time of pressing is held in
the concave grooves 7, and further held water is transferred out of
the press portion by the rotation of the belt itself. Therefore, it
is required that the projections 8 provided on the resin layer 5 on
the press roll side serve to improve the mechanical characteristics
in terms of abrasion, bending fatigue, crack, and compression
fatigue caused by a vertical pressing force of the press roll 101
and a friction or bending fatigue of the belt in a shoe press
area.
[0007] From these reasons, as the material forming the resin layers
5, 6 of the shoe press belt 1, polyurethane excellent in the crack
resistance is broadly employed (e.g., refer to Japanese Patent
Unexamined Publication Nos. JP-A-11-247086 and
JP-A-2004-52204).
[0008] However, in recent years, the service environments of the
shoe press belt 1 are increasingly severe as the operation speed or
the pressure of the press portion is increased owing to higher
productivity of paper. Therefore, it is required that various
mechanical characteristics are further improved.
SUMMARY OF THE INVENTION
[0009] Accordingly, it is an object of the invention to provide a
shoe press belt having the excellent properties such as abrasion
resistance, bending fatigue resistance, crack resistance, and
compression fatigue resistance. In order to achieve the above
object, the present invention provides a shoe press belt comprised
of polyurethane and a substrate, characterized in that the
polyurethane contains a non-reactive polydimethylsiloxane liquid
substance and has a JIS A hardness of 93.degree. to 96.degree..
[0010] Since the shoe press belt of the invention is composed of
polyurethane forming the resin layers, which contains non-reactive
polydimethylsiloxane and has a JIS A hardness of 93.degree. to
96.degree., it has more excellent mechanical characteristics such
as abrasion resistance, bending fatigue, crack resistance, and
compression fatigue resistance than conventionally and is good for
service under severe conditions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic view showing a shoe press
mechanism;
[0012] FIG. 2 is a cross-sectional view showing a shoe press
belt;
[0013] FIG. 3 is a schematic view showing an apparatus for
measuring the occurrence number of cracks; and
[0014] FIG. 4 is a schematic view showing an apparatus for
measuring the abrasion loss.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] The present invention will be described below with reference
to the accompanying drawings.
[0016] A shoe press belt of the invention is integrally formed with
the resin layers 5, 6 on both sides of a substrate 3, and provided
with many concave grooves 7 on a resin layer 5 on the side of a
roll press, as shown in FIG. 2. The resin layers 5, 6 are formed of
polyurethane containing a non-reactive polydimethylsiloxane liquid
substance and having a JIS A hardness (hereinafter referred to as a
hardness) of 93.degree. to 96.degree..
[0017] Polyurethane containing the non-reactive
polydimethylsiloxane liquid substance and having a hardness of
93.degree. to 96.degree. is prepared from urethane prepolymer, a
curing agent, and non-reactive polydimethylsiloxane liquid
substance by adjusting their mixture ratio to have a hardness of
93.degree. to 96.degree. when cured (hereinafter referred to as a
"hardness 93.degree. to 96.degree. product containing non-reactive
polydimethylsiloxane liquid substance"). Also, polyurethane not
containing non-reactive polydimethylsiloxane liquid substance
prepared by adjusting the mixture ratio of urethane prepolymer and
curing agent to have a hardness of 98.degree. (hereinafter referred
to as a "hardness 98.degree. product not containing non-reactive
polydimethylsiloxane liquid substance"), and polyurethane
containing non-reactive polydimethylsiloxane liquid substance
prepared by adjusting the mixture ratio of urethane prepolymer,
curing agent and non-reactive silicone oil liquid substance to have
a hardness of 90.degree. to 93.degree. (hereinafter referred to as
"hardness 90.degree. to 93.degree. product containing non-reactive
polydimethylsiloxane liquid substance") may be blended.
[0018] Urethane prepolymer is prepared by reacting an organic
diisocyanate and polyol by a well-known method. Suitable examples
of organic diisocyanate include paraphenylene diisocyanate (PPDI),
triden diisocyanate (TODI), isophorone diisocyanate (IPDI),
4,4'-methylene bis(phenylisocyanate) (MDI),
toluene-2,4-diisocyanate (2,4-TDI), toluene-2,6-diisocyanate
(2,6-TDI), naphthalene-1,5-diisocyanate (NDI),
diphenyl-4,4'-diisocyanate, dibenzyl-4,4'-diisocyanate,
stilbene-4,4'-diisocyanate, benzophenone-4,4'-diisocyanate, 1,3-
and 1,4-xylene diisocyanate, 1,6-hexamethylene diisocyanate,
1,3-cyclohexyl diisocyanate, 1,4-cyclohexyl diisocyanate (CHDI),
1,1'-methylene-bis(4-isocyanate hexamethylene), three geometrical
isomers (abbreviated collectively as H.sub.12MDI) and their
mixtures.
[0019] High molecular weight polyol having long chain, for example,
having a molecular weight (MW) of more than 250, is typically
employed to form prepolymer. The high molecular weight polyol
having long chain provides the rein flexibility and elastomer
property. The high molecular weight polyol, typically polyether
polyol, polyester polyol, or hydrocarbon polyol having a number
average molecular weight of at least 250, is often employed to
prepare prepolymer. The molecular weight is preferably from about
500 to 6000, but more preferably in a range from about 650 to about
3000. However, the high molecular weight polyol has a high
molecular weight of about 10,000, and a low molecular weight of
about 250. Moreover, the low molecular weight glycol and triol
having a molecular weight of 60 to 250 may be contained.
[0020] Suitable polyalkyleneetherpolyol is represented by a general
formula "HO(RO).sub.nH", where R is alkylene radical, and n is an
integer in which polyether polyol has a number average molecular
weight of at least 250. Polyalkylene ether polyol is well-known
polyurethane product component and prepared by polymerizing cyclic
ether, for example, alkylene oxide, glycol, and dihydroxy ether by
a well-known method. The average functional group number is from
about 2 to about 8, preferably from about 2 to about 3, or more
preferably from about 2 to about 2.5.
[0021] Polyester polyol is typically prepared by reacting dibasic
acid (usually adipic acid, but other components, for example,
glutaric acid, succinic acid, azelaic acid, sebacic acid, or
phthalic anhydride may exist) with diol, for example, ethylene
glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,6-hexylene
glycol, diethylene glycol, or polytetramethyleneetherglycol). If
the chain is branched or ultimately bridged, polyol, for example,
glycerol, trimethylolpropane, penthaerythritol, or sorbitol can be
employed. Diester may be employed instead of dibasic acid. Some of
polyester polyol is produced employing caprolactam, or dimerization
unsaturated fatty acid.
[0022] Hydrocarbon polyol is prepared from ethylene unsaturated
polymer, for example, ethylene, isobutylene, and 1,3-butadiene. For
example, polybutadienpolyol is employed, such as "Poly-bd R-45HT"
made by Atochem, "DIFOL" made by Amoco Corp., and "Kratone" L
polyol" made by Shell Chemical CO.
[0023] Polycarbonate polyol is also usable, and prepared by
reacting glycol (e.g., 1,6-hexyline glycol) and organic carbonate
(e.g., diphenylcarbonate, diethylecarbonate, or
ethylenecarbonate).
[0024] A curing agent or chain elongation agent for use with
prepolymer is selected from various kinds of organic diamine or
polyol materials which are usually used and well known. Preferable
material is solid or liquid having a low melting point.
Particularly, diamine, polyol, and a blend thereof, having a
melting point of below 140.degree. C. are preferred. Generally,
diamine or polyol is currently employed as the curing agent for
polyurethane in this industry. The curing agent is generally
selected on the basis of the required reactivity, required property
needed in specific uses, required processing conditions, and a
desired pot life. A well-known catalyst may be employed in
combination with the curing agent.
[0025] The curing agent may be aliphatic diol or aromatic diamine.
Suitable examples of aliphatic diol include 1,4-butadiendiol,
1,3-propanediol and 1,6-hexanediol. Also, suitable examples of
aromatic diamine include dimethyl thio toluene diamine (DMTDA), and
3,3'-dichrolo 4,4'-diaminodiphenylmethane (MBOCA). Among others,
DMTDA and MBOCA are preferable. Also, various isomers of DMTDA
exist depending on the substitution position of dimethylthio group
and amino group, but may be employed in the form of isomer mixture
and is available as "(ETHACURE) 300" made by Albemarle Corporation
in United States.
[0026] The use percentage of urethane prepolymer and the curing
agent is adjusted depending on the hardness, but it is preferable
that the equivalent ratio of active hydrogen group of curing agent
and isocyanate group of urethane prepolymer is from 0.9 to
1.10.
[0027] The non-reactive polydimethyl siloxane liquid substance is
preferably high molecular compound containing siloxane, such as
silicone oil, silicone rubber and silicone elastomer. Those
silicones may be commercially available from Wacker Silicones
Corporation with a tradename "Silicone Fluids SWS-101", belonging
to the silicone fluids, and "KF96" made by Shinetsu Chemical.
[0028] The non-reactive polydimethylsiloxane liquid substance may
have any viscosity (used as a criterion of chain length in this
specification) as far as it is effective to improve the abrasion
resistance of the product without losing the friction
characteristic of the product containing it. Accordingly, the
viscosity is 200,000 cst or more, and preferably in a range from
5,000 to 100,00 cst.
[0029] Also, the non-reactive polydiraethylsiloxane liquid
substance is blended at a percentage of 0.5 to 25mass % to the
total amount of urethane prepolymer and the curing agent.
[0030] The shoe press belt is produced by applying and impregnating
a mixture of hardness 93.degree. to 96.degree. product containing
non-reactive polydimethylsiloxane liquid substance or hardness
93.degree. product containing non-reactive polydimethylsiloxane
liquid substance and hardness 98.degree. product not containing
non-reactive polydimethylsiloxane liquid substance onto the
substrate, curing the mixture by heating, then polishing the
surface to have a predetermined thickness, and forming the concave
grooves on one surface in the same manner as conventionally, as
shown in FIG. 2. Though the curing conditions are appropriately
selected depending on the kind of used product, the heating
temperature is from 20 to 150.degree. C., preferably from 90 to
140.degree. C., and the heating time is 30 minutes or longer.
[0031] The substrate may be a film or knit, narrow strip made of
polyamide, polyester, aromatic polyamide, aromatic polyimide, or
high strength polyethylene, and wound like spiral, for example.
EXAMPLES
[0032] This invention will be described below by way of example,
but is not limited to those examples.
Examples 1 to 8 and Comparative Examples 1 to 12
[0033] Employing hardness 93.degree. product containing
non-reactive polydimethylsiloxane liquid substance (adiprenestream
"E493" made by Uniroyal), hardness 93.degree. product not
containing non-reactive polydimethylsiloxane liquid substance
(adiprene LF930A made by Uniroyal), and hardness 98.degree. product
not containing non-reactive polydimethylsiloxane liquid substance
(adiprene LF600D made by Uniroyal), a mixture of them is applied on
both the surfaces of a substrate made from polyester fabric, and
cured by heating, whereby the concave grooves (0.5 to 4 mm wide,
0.5 to 5 mm deep) are formed with the land part interval between
adjacent waterways being 2 to 3 mm on one surface to produce a belt
sample. In the comparative examples 1 to 12, polyurethane contains
no non-reactive polydimethylsiloxane liquid substance.
[0034] And for each belt sample, (1) hardness, (2) occurrence
number of cracks, (3) abrasion loss and (4) VV reduction ratio
under pressure were measured. A measuring method is as follows, and
the results are listed in the table.
[0035] (1) Hardness
[0036] The hardness was measured employing a JIS A durometer.
[0037] (2) Occurrence Number of Cracks
[0038] Both ends of a belt sample 51 were pinched by the clamp
hands 52, 52, and the clamp hands 52, 52 were linked and
reciprocated in the left and right direction in the figure, as
shown in FIG. 3. At this time, the tension applied on the belt
sample 51 was 3 kg/cm, and the reciprocation speed was 40 cm/sec.
Also, the belt sample 51 was carried by a rotary roll 53 and a
press shoe 54, and the press shoe 54 was moved in a direction of
the rotary roll to pressurize the belt sample 51 with a pressure of
36 kg/cm.sup.2. A lubricant oil was sprayed from the press shoe
side onto the belt sample 51 during the reciprocating movement to
suppress generation of heat. The belt sample 51 was reciprocated in
this way, whereby the number of reciprocations was measured until a
crack occurred on a face of the belt sample 51 opposed to the
rotary roll.
[0039] (3) Abrasion Loss
[0040] Employing an apparatus as shown in FIG. 4, the belt sample
51 was attached on the lower part of a press board 55, and rotated
with a rotary roll 56 having a rubber 57 on the outer circumference
pressed against a lower face (measurement object face) thereof. At
this time, the pressure with the rotary roll 56 was 3 kg/cm, and
the rotation rate of the rotary roll 56 was 100 m/min, whereby the
belt sample was rotated for ten minutes. After rotation, a decrease
amount in the thickness of the belt sample 51 was measured.
[0041] (4) VV Reduction Ratio Under Pressure
[0042] Two belt samples were prepared, uncured silicone resin
(before curing) was filled in the concave grooves of one belt
sample, scraped smoothly over the belt grooves by a scoop, and
cured without pressure.
[0043] Uncured silicone resin (before curing) was filled in the
concave grooves of another belt sample, scraped smoothly over the
belt grooves by a scoop, and cured under a pressure of 40 kg. After
curing, resin was taken out of the concave grooves of each belt
sample, and the groove sizes (groove width, groove height, groove
length) were measured by a microscope, whereby the VV reduction
ratio under pressure was calculated from the following expression.
[(VV without pressure-VV under pressure)/VV without
pressure].times.100%
[0044] TABLE-US-00001 TABLE 1 Occurrence VV Adiprene Adiprene
Adiprene Amine Number of Abra- reduc- E493 LF930A LF950 A LF600D
curing Hardness cracks sion tion Total NCO agent Equivalent JIS
(10000 loss ratio eval- 5.12 5.07 6.01 7.18 NCO (NH2) NH2/NCO
ratio-A times) (mm) (%) uation Comparative 90 0 0 10 5.33 DMTDA
0.95 92 >30 0.25 41 bad example 1 Example 1 70 0 0 30 5.74 DMTDA
0.96 93 20-25 0.35 30 good Example 2 50 0 0 50 6.15 DMTDA 0.98 94
15-20 0.35 23 excel- lent Example 3 40 0 0 60 6.36 DMTDA 1.01 95
10-15 0.45 18 good Example 4 30 0 0 70 6.56 DMTDA 1.03 96 5>
0.60 14 better Comparative 20 0 0 80 6.77 DMTDA 1.05 97 5> 0.65
11 bad example 2 Comparative 90 10 0 0 5.12 MOCA 0.95 92 >30
0.25 43 bad example 3 Example 5 90 0 0 10 5.33 MOCA 0.97 93 20-25
0.25 35 better Example 6 70 0 0 30 5.74 MOCA 0.99 94 15-20 0.25 24
excel- lent Example 7 50 0 0 50 6.15 MOCA 1.01 95 5-10 0.35 19 good
Example 8 40 0 0 60 6.36 MOCA 1.03 96 5> 0.50 15 better
Comparative 30 0 0 70 6.56 MOCA 1.05 97 5> 0.55 17 bad example 4
Comparative 0 0 100 0 6.01 DMTDA 0.97 94 15-20 0.65 28 bad example
5 Comparative 0 90 0 10 5.28 DMTDA 0.95 92 >30 0.65 40 bad
example 6 Comparative 0 70 0 30 5.70 DMTDA 0.96 93 15-20 0.60 30
bad example 7 Comparative 0 50 0 50 6.13 DMTDA 0.98 94 5-10 0.65 23
bad example 8 Comparative 0 0 100 0 6.01 MOCA 0.99 95 10-15 0.70 25
bad example 9 Comparative 0 90 0 10 5.28 MOCA 0.97 93 5-10 0.75 31
bad example 10 Comparative 0 70 0 30 5.70 MOCA 0.99 94 5> 0.70
24 bad example 11 Comparative 0 50 0 50 6.13 MOCA 1.01 95 5>
0.70 18 bad example 12 Target .gtoreq.10 0.5.ltoreq. 30.ltoreq.
[0045] As seen from the table, the belt sample made of polyurethane
containing non-reactive polydimethylsiloxane liquid substance and
having a hardness of 93.degree. to 96.degree. was more excellent in
the crack resistance and the abrasion resistance and had less
deformation in the concave grooves than any other belt sample.
[0046] While there has been described in connection with the
preferred embodiments of the present invention, it will be obvious
to those skilled in the art that various changes and modification
may be made therein without departing from the present invention,
and it is aimed, therefore, to cover in the appended claim all such
changes and modifications as fall within the true spirit and scope
of the present invention.
* * * * *