Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Graphite – coal – or elemental carbon
Reexamination Certificate
2001-07-05
2004-02-24
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Graphite, coal, or elemental carbon
C015S250001, C015S250361, C428S325000, C428S336000
Reexamination Certificate
active
06696391
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a wiper blade rubber for use in vehicles and the like and also relates to a coating agent coated on this wiper blade rubber.
2. Description of the Related Art
The wiper blade rubber is subjected to a surface treatment with chlorine so as to reduce the frictional resistance in wiping and improve the abrasion property at the distal end of the lip part which comes into contact with glass. This chlorine treatment comprises dipping at least the lip part of a wiper blade rubber in a chlorine-based solvent to harden the surface. When a wiper blade rubber treated with chlorine is operated in the water-wetted state on a glass surface subjected to a water-repellent treatment, chattering is generated. Furthermore, after the wiper is operated 100,000 times, a large number of streaks remain in the sensuous evaluation of the wiping property.
In order to ensure good visual field from a motor car or the like, the glass is sometimes subjected to a water-repellent treatment. According to the studies by the present inventors, this treatment has been confirmed to cause a problem in that the glass subjected to a water-repellent treatment repels water in a ball form and therefore, residual streaks and the like are not easily generated, however, since a water film is difficult to form, the glass and the rubber are liable to come into direct contact and even in the wet condition, the coefficient of friction particularly during the low-speed operation increases to be comparable with the coefficient of static friction in the dry condition and in turn, the coefficient of static friction in the wet condition becomes excessively large in comparison with the case of clean glass, as a result, the velocity dependence of the friction coefficient increases, so that a chattering (noise) is readily generated.
Even on a glass surface not subjected to a water-repellent treatment, when wax or the like is applied, chattering is sometimes readily generated because a water film is difficult to form. Also, the wiper blade rubber generates remaining streaks or uneven wiping, due to abrasion on use for a long period of time or due to mesh-geared sand, which inhibits the visual field.
Furthermore, with a long-term use, even a glass subjected to a water-repellent treatment undergoes partial loss of the water-repellent treatment and the glass substrate is exposed. Accordingly, the wiper blade rubber must have a good wiping performance and high noise-preventing effect for both a glass subjected to a water-repellent treatment and a clean glass.
By taking account of these problems, the object of the present invention is to provide a wiper blade rubber capable of exhibiting good wiping performance and high noise-preventing effect for both a glass subjected to a water-repellent treatment and a clean glass.
SUMMARY OF THE INVENTION
As a result of extensive investigations to achieve the above-described object, it has been found that this object can be attained by providing the following and the present invention has been accomplished based on this finding.
(1) A coating agent for wiper blade rubbers, comprising a particulate solid lubricant and a binder for sticking the solid lubricant to a wiper blade rubber, wherein the binder has a 0.5% modulus (substitute for an elastic modulus) of about 1 MPa or more and an elongation to break of about 1% or more after drying or curing.
(2) The coating agent for wiper blade rubbers as described in (1), wherein the volume ratio of the solid lubricant to the binder is from about 0.25 to about 1.0.
(3) The coating agent for wiper blade rubbers as described in (1), wherein the volume ratio of the solid lubricant to the binder is from about 0.4 to about 0.7.
(4) The coating agent for wiper blade rubbers as described in (1) to (3), wherein the solid lubricant is graphite particles.
(5) The coating agent for wiper blade rubbers as described In (1) to (4), wherein the binder is selected from the group consisting of urethane resins, polyamideimides resin and epoxy resins.
(6) The coating agent for wiper blade rubbers as described in (1) to (5), wherein the binder has a 0.5% modulus of about 4 MPa or more and an elongation to break of about 2% or more after drying or curing
(7) A wiper blade rubber having a coating film on both surfaces of a lip part thereof, the coating film comprising a particulate solid lubricant and a binder and the binder having a 0.5% modulus of about 1 MPa or more and an elongation to break of about 1% or more.
(8) The wiper blade rubber as described in (7), which is produced by a method comprising applying a coating agent on both surfaces of the lip part of a tandem-shaped wiper blade rubber, drying or curing the coating agent and cutting the distal end of the lip part to form coating films terminating on the lateral surface of the lip part.
(9) The wiper blade rubber as described in (7) and (8), wherein the coating film has a thickness of about 2 to about 10 &mgr;m.
(10) The wiper blade rubber as described in (7) to (9), wherein when the terminal voltage of a motor for driving the wiper blade rubber is 7 V, the coefficient of static friction with a glass subjected to a water-repellent treatment is about 0.65 or less.
(11) The wiper blade rubber as described in (7) to (10), wherein the volume ratio of the solid lubricant to the binder is from about 0.25 to about 1.0.
(12) The wiper blade rubber as described in (7) to (10), wherein the volume ratio of the solid lubricant to the binder is from about 0.4 to about 0.7.
(13) The wiper blade rubber as described in (7) to (12), wherein the solid lubricant comprises graphite particles.
(14) The wiper blade rubber as described in (7) to (13), wherein the binder is selected from the group consisting of urethane resins, polyamideimide resins and epoxy resins.
(15) The wiper blade rubber as described in (7) to (14), wherein the binder has a 0.5% modulus of about 4 MPa or more and an elongation to break of about 2% or more after drying or curing.
(16) A method for producing a wiper blade rubber, comprising applying a coating agent on both surfaces of the lip part of a tandem-shaped wiper blade rubber, drying or curing the coating agent and cutting the distal end of the lip part to form coating films terminating on the lateral surface of the lip part, wherein the coating agent comprises a particulate solid lubricant and a binder and the binder has a 0.5% modulus of about 1 MPa or more and an elongation to break of about 1% or more after drying or curing.
(17) The method as described in (16), wherein the step of drying or curing the coating agent is a step of heat-treating the coating agent under conditions not more severe than about 120° C. and about 30 minutes.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a cross-sectional view of a wire blade rubber having a tandem-shaped coating film used in the Mode for Carrying out the Invention and in the Examples.
FIG. 2
is a graph showing the relationship between the modulus at the elongation of 0.5% and the coefficient of static friction of various binders.
FIG. 3
is a graph showing the relationship between the transfer speed and the coefficient of friction on a water-repellent glass, of wiper blade rubbers of Example 1 and Comparative Example 1.
FIG. 4
is a graph showing the relationship between the transfer speed and the coefficient of friction on a glass not subjected to a water-repellent treatment, of wiper blade rubbers of Example 1 and Comparative Example 1.
FIG. 5
is a graph showing the relationship between the number of wiping operations and the sensory evaluation point on a clean glass not subjected to a water-repellent treatment.
FIG. 6
is a graph showing the abraded area (&mgr;m
2
) is when a clean glass not subjected to a water-repellent treatment is wiped 100,000 times in Example 1 and Comparative Example 1.
FIG. 7
is a view showing the standard for the point number in the sensuous evaluation of wiping of FIG.
5
.
DETAILED DESCRIPTION OF THE INVENTION
A wiper blade rubber capable of
Goto Shinya
Itoh Kouitsu
Ohsako Hiroaki
Torii Naoki
Denso Corporation
Harness Dickey & Pierce PLC
Howard Jacqueline V.
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