Patent Publication Number: US-2019176764-A1

Title: Rubber wiper blade element with friction reducing agent that continuously migrates to the surface

Description:
This U.S. Divisional patent application claims priority to U.S. Utility application Ser. No. 14/736,409, filed Jun. 11, 2015, and is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is generally related to windscreen wiper devices, and more precisely to wiper strips of windscreen wiper devices. 
     2. Related Art 
     The wiper strips of typical windscreen wiper devices, or wiper blades, are formed of a rubber material which seals against a vehicle&#39;s windshield to drive water, snow or other elements away therefrom. Materials having, among other things, a good resistance to abrasion, a low frictional surface and good slip properties are generally chosen to give the wiper blades a good wipe quality. Oftentimes, a material which improves one or more of these qualities has a negative effect on others. For example, soft rubbers may produce wiper strips which exhibit exceptional wipe quality but also have an undesirably high frictional resistance, which could reduce the lifespans of such wiper blades. 
     Some wiper manufacturers have attempted to improve the performance of their wiper blades by applying a coating having hydrophobic properties to the wiper strips. Such coatings allow the wiper strip to be formed of a harder rubber, resulting in reduced friction and longer life, without compromising wipe quality. However, such coatings may be very costly and/or difficult to apply to the wiper strip. The coatings may also wear out over time due to extended use or abuse. When the coating wears away, the untreated or uncoated rubber is exposed, thereby increasing the friction between the wiper strip and the windshield, which results in a reduced wipe quality. 
     SUMMARY OF THE INVENTION 
     One aspect of the present invention provides for a windscreen wiper device for a vehicle with improved performance and lifespan. The windscreen wiper device includes a longitudinally extending wiper strip of a flexible material. At least a portion of the flexible material of the wiper strip comprises a friction reducing agent including at least one amide. 
     Upon vulcanization, a portion of the friction reducing agent migrates to the outer surface of the wiper strip and forms a friction reducing film along an exposed outer surface of the flexible material. In addition, as the friction reducing film wears down during use of the wiper device, portions of the friction reducing agent continuously migrate to the outer surface of the wiper strip to replenish or renew the friction reducing film. 
     The friction reducing film provides a low friction interface between the flexible material of the wiper strip and a windshield of the vehicle under both wet and dry conditions. The low friction minimizes the load on the wiper device and thus extends the life of the wiper device. The friction reducing film also has hydrophobic properties, and thus can prevent or reduce the size of water beads, and also prevent the build-up of water, ice, and snow. The friction reducing film may also reduce noise, such as squeak and reversal chirp, typically associated with high friction between the wiper strip and the windshield. 
     Another aspect of the present invention is a method of making a windscreen wiper device. The method includes the step of forming a longitudinally extending wiper strip of a flexible material which includes a friction reducing agent, wherein the friction reducing agent includes at least one amide. 
     Yet another aspect of the present invention is a method of making a windscreen wiper device including a wiper strip with a friction reducing film. The method includes the step of forming a longitudinally extending wiper strip of a flexible material including a mixture of rubber and a friction reducing agent, wherein the friction reducing agent includes at least one amide. The method further includes vulcanizing the flexible material of the wiper strip. The vulcanizing step includes forming the friction reducing film on an outer surface of the flexible material, and the friction reducing film includes the at least one friction reducing agent. 
     Another aspect of the invention provides a windscreen wiper element, comprising a wiper element body fabricated of a molded or extruded rubber, polymer, or plastic base material and including a longitudinally extending wiper lip. The base material has incorporated therein an additional friction reducing agent that is operative during use of the wiper element to migrate to an outer surface of the wiper element and to provide a hydrophobic effect to the outer surface that is greater than that provided by the base material itself. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features and advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
         FIG. 1  is a perspective and elevation view of an exemplary windscreen wiper device; 
         FIG. 2  is a cross-sectional view of the exemplary windscreen wiper device taken through line  2 - 2  of  FIG. 1 ; 
         FIG. 3A  is a perspective and elevation view of a wiper strip formed of a flexible material of the windscreen wiper device of  FIG. 1 ; 
         FIG. 3B  is an enlarged view taken of a wiping portion of the wiper strip of  FIG. 3A  showing a friction reducing agent disposed throughout the flexible material and a friction reducing film along an outer surface of the wiper strip; 
         FIG. 4  is a cross-sectional view of a wiper strip, carrier, and spoiler of a windscreen wiper device according to another exemplary embodiment; and 
         FIG. 5  is a cross-sectional view of a wiper strip including a friction reducing agent disposed throughout a flexible material according to yet another exemplary embodiment. 
     
    
    
     DESCRIPTION OF THE ENABLING EMBODIMENT 
     Referring to the Figures, wherein like numerals indicate corresponding parts throughout the several views, an exemplary windscreen wiper device  20  (or a wiper blade) constructed according to one aspect of the invention is generally shown in  FIG. 1 . Referring now to the cross-sectional views of  FIGS. 2 and 3A , the exemplary windscreen wiper device  20  includes a wiper strip  22 , also referred to as a wiper element. The wiper strip  22  has a wiping portion  24 , also referred to as a wiper lip, a spoiler portion  26  and a hinge portion  28  all integrally connected to one another and formed as one piece of material with the hinge portion  28  being disposed between the wiping and spoiler portions  24 ,  26 . The wiper strip  22  presents an outer surface  27  for engaging a windshield of a vehicle. The spoiler portion  26  presents a longitudinally extending channel  30 , and a carrier  32  (sometimes referred to as a “flexor”) is disposed in the channel  30 . The carrier  32  is of a spring-like material (such as spring steel) and operatively supports and biases the wiper strip  22  into a predetermined configuration. Referring back to FIG.  1 , the exemplary windscreen wiper device  20  is a “beam” style device because it lacks the levers and frame found on traditional windscreen wiper devices. As such, the exemplary carrier  32  (shown in  FIG. 2 ) is self-biased into a curved shape to bias the wiper strip  22  into a curved configuration, thereby allowing it to conform to windshields of differing curvatures. The exemplary windscreen wiper device  20  also includes a connecting device  34  for connection with a wiper arm (not shown). Additionally, end caps  35  are secured to either the wiper strip  22  or to the carrier  32  at the ends of the exemplary windscreen wiper device  20 . 
     However, it should be appreciated that other windscreen wiper device designs can be employed. For example, the windscreen wiper device can comprise a traditional style having a frame with a plurality of levers and a generally linearly biased carrier. The windscreen wiper device  20  could also include a separate wiper strip  22 , carrier  32 , and spoiler  26 , as shown in  FIG. 4 . In this embodiment, the wiper strip  22  presents two oppositely facing lateral grooves. Two longitudinally extending strips, which together form the carrier  32 , are disposed in the lateral grooves. The spoiler  26  is a separate component surrounding the carrier  32  and a portion of the wiper strip  22 .  FIG. 5  is a cross-sectional view of yet another wiper strip  22  which could be employed in the wiper device  20 . 
     The exemplary wiper strip  22  is formed of a flexible and elastic base material, such as rubber, plastic, and/or polymer, for sealing against a vehicle&#39;s windshield (not shown) and for driving rain, snow or other elements away therefrom. In the example embodiments, the rubber used to form the flexible material is natural rubber or polyisoprene. However, other types of rubber could be employed, such as synthetic rubber. In another embodiment, the flexible material used to form the wiper strip  22  includes a mixture of different rubbers, for example a blend of natural and synthetic rubber. 
     Referring now to  FIGS. 3A and 3B , at least a portion of the flexible material of the wiper strip  22  comprises a friction reducing agent  36 . In the exemplary embodiments, the friction reducing agent  36  is provided as a plurality of particles disposed homogenously and compounded throughout the flexible material. However, the friction reducing agent  36  could be provided in other forms. 
     The friction reducing agent  36  is typically integrated into the formulation used to manufacture of the flexible material of the wiper strip  22 . In the exemplary embodiments, the formulation includes 2 parts to 5 parts of the friction reducing agent  36  per 100 parts of unvulcanized rubber. The size and shape of the friction reducing agent  36  can vary. The composition of the friction reducing agent  36 , however, includes at least one amide. The at least one amide can include any component in the amide chemical family. Typically, the entire friction reducing agent  36  consists of one or more amides. In the exemplary embodiments, the one or more amides are selected from the group consisting of oleamides and euricimides. In one example embodiment, the friction reducing agent  36  includes or consists of at least one oleamide. In another example embodiment, the friction reducing agent  36  includes or consists of at least one euricimide. In yet another example embodiment, the friction reducing agent  36  includes or consists of a mixture of different amides. For example, the friction reducing agent  36  could include or consists of a mixture at least one oleamide and at least one euricimide. The friction reducing agent  36  could alternatively include or consists of a mixture at least one oleamide and at least one euricimide in another example embodiment, the friction reducing agent  36  includes a mixture of amides having different molecular weights, for example a mixture of different euricimides having different molecular weights. 
     The at least one amide is used as the friction reducing agent  36  due to its low molecular weight and adapted compatibility. Upon vulcanization, a portion of the friction reducing agent  36  will migrate to the outer surface  27  of the flexible material of the wiper strip  22  and create a friction reducing film  38 , as shown in  FIG. 3B , which engages the windshield during use of the wiper device  20 . The friction reducing film  38  includes the same at least one amide used as the friction reducing agent  36 . The friction reducing film  38  can have various different thicknesses and can be located along a portion of the outer surface  27  or the entire outer surface  27  of the wiper strip  22 . In the exemplary embodiment, the friction reducing agent  36  is added to the flexible material such that the friction reducing film  38  forms along at least the wiping portion  24  of the wiper strip  22 . However, the friction reducing film  38  may also be present along the channels and/or other portions of the wiper strip  22 . 
     Due to the low molecular weight and adapted compatibility of the vulcanized friction reducing agent  36  including the at least one amide, a small portion of the friction reducing agent  36  continuously migrates to the outer surface  27  of the wiper strip  22  to replenish or renew any of the friction reducing film  38  which may have been removed or worn away during use of the wiper device  20 , while a larger portion of the friction reducing agent  36  remains in the body of the flexible material. The friction reducing film  38  provides a low friction interface between flexible material of the wiper strip  22  and the windshield of the vehicle under wet and dry conditions. As a function of product life, as the friction reducing film  38  and/or outer surface  27  of the flexible material wears due to use, additional portions of the friction reducing agent  36  present in the body of the flexible material migrate to the exposed outer surface  27  to replenish the friction reducing film  38 . 
     The low friction provided by the friction reducing film  38  minimizes the load on the wiper device  20  and thus extends the life of the wiper device  20 , compared to wiper devices experiencing a greater amount of friction between the wiper strip and the windshield. In addition, the friction reducing film  38  provides hydrophobic properties, and thus can prevent or reduce the size of water beads, and prevent the build-up of water, ice, or snow. For example, water formed along the friction reducing film  38  will bead and run off the outer surface  27 , i.e. create a low surface tension. The friction reducing film  38  may also reduce noise, such as squeak and reversal chirp, typically associated with high friction between the wiper strip  22  and the windshield during normal operating conditions. 
     Another aspect of the present invention provides for a method of making the windscreen wiper device  20 . The method includes the step of forming the longitudinally extending wiper strip  22  of the flexible material including the friction reducing agent  36 , wherein the friction reducing agent  36  includes the at least one amide. In the exemplary embodiments, the at least one amide is provided in the form of a plurality particles, and the particles are mixed together with the unvulcanized rubber material used to form the flexible material. For example, the formulation of the flexible material could include 2 to 5 parts of the at least one amide per 100 parts of the rubber. 
     The method further includes forming the mixture of amide and rubber into the desired shape of the wiper strip  22 , and vulcanizing the mixture to form the flexible material. The forming step typically includes extruding or molding the mixture into the desired shape. The vulcanizing step typically includes curing the mixture, which includes heating and modifying the mixture to form cross-links in the rubber material. The vulcanizing step can be conducted during the shaping step, or as a separate step. During the vulcanizing step, a portion of the friction reducing agent  36  migrates to the outer surface  27  of the flexible material to form the friction reducing film  38 . The friction reducing film  38  includes the at least one amide, which has the same composition as the friction reducing agent  36  present in the body of the flexible material. 
     The method of manufacturing the wiper device  20  can also include providing at least one carrier  32  of a spring-like material to operatively support and bias the wiper strip  22  into a predetermined configuration; and a connecting device  34  for connection with a wiper arm. However, the wiper strip  22  including the friction reducing agent  36  can be used in other wiper device designs. For example, the method can alternatively include manufacturing a wiper device  20  having a conventional design, or another design. 
     It is to be understood that the above detailed description is with regard to some presently preferred embodiments, and that other embodiments readily discernible from the disclosure herein by those having ordinary skill in the art are incorporated herein and considered to be within the scope of any ultimately allowed claims.