JP4427333B2 - Windshield wiper wiper blade and method of making the wiper blade - Google Patents

Description

The invention relates to a wiper blade of the type described in the superordinate conception of the independent claims and to a method for manufacturing the wiper blade.

It is known from practical use that the windshield wiper wiper blade is provided with a friction-reducing coating, which is a glass or plastic shield of an elastomer forming the wiper blade, for example natural rubber or chloroprene rubber. The friction coefficient at the time of sliding friction along is reduced. This is particularly important when the windshield wiper is operated on a dry or nearly dry glass plate, for example to remove insects or dust from the shield, during light rain, or in showers. For example, when entering a tunnel or a garage in the middle. In that case, the coefficient of friction that increases when the shield is dry can lead to strong stagnation and judder, and even the windshield wiper to stop. Various technologies have been proposed to reduce the coefficient of friction when using wiper blades on a dry shield. For example, it is known to halogenate a wiper blade made of rubber. For example, the rubber is chlorinated or brominated, this leads to hardening of the surface of the rubber, natural rubber, significantly reduces the dry friction value mu _TR to glass. Subsequently, the wiper blade is cut to the desired dimensions and post-treated with a graphite suspension. Graphite remaining on the surface, further lower the dry friction value mu _TR.

  However, with this type of treatment of rubber, accurate and therefore laborious process execution is essential. This is because it could otherwise damage the rubber, i.e. the wiper blade material, and thus the quality of wiping desired to be achieved by the wiper blade. Furthermore, this type of treatment is problematic for environmental reasons.

A method of the kind mentioned at the beginning is known from JP 10-7903 A. In this method, a windshield wiper wiper blade is provided with a coating, which consists of soluble polyamide, additives and dry lubricants such as PTFE, polyethylene, MoS ₂ , graphite or talc.

  From JP-A-4-309534, it is known that a wiper blade of a windshield wiper is coated with methoxymethylated polyamide in order to reduce the friction value against the glass plate. It is performed before vulcanization of the basic shape made of rubber elastic material. During vulcanization, the methoxymethylated polyamide crosslinks and thereby adheres to the basic shape. In some cases, a dry lubricant is added to the coating to further reduce the friction value.

  Furthermore, it is known from U.S. Pat. No. 6,044,709 to produce allyloxymethyl polyamides used as binders for photoconductive layers.

Advantages of the Invention According to the method of manufacturing a windshield wiper wiper blade according to the present invention with the features described in the superordinate concept of claim 1, a friction reducing coating is manufactured from a polymer solution, The polymer solution contains a starting polymer that has been modified by having unsaturated side chains that are crosslinkable, and the modified starting polymer is crosslinked after application to the basic shape. did.

  Coatings that can be cross-linked with suitable radical initiators, such as AIBN 2,2'-azobis- (2-methylpropionitrile), made in that way are low on wiper blades, especially against dry or wiped vehicle shields. It leads to the friction value.

  As a result, the force required for the movement of the wiper arm supporting the wiper blade along the vehicle shield is very small. Therefore, the wiper arm used for driving the wiper arm can be directly or via an interlocking mechanism. The driven electric motor can be designed smaller compared to the electric motor used in an uncoated wiper blade as in the present invention, which also reduces the energy consumption as well as the cost of producing the motor. Leads to a decrease. This is particularly advantageous for very large and flat shields where very long wiper arms and wiper blades are required. Even when using such a shield, the electric motor used can be designed to be relatively small if wiper blades made according to the method according to the invention are used.

  Furthermore, based on the low friction value of the wiper blade, there is little noise generated when operating the windshield wiper, especially on a dry or wiped shield. This increases the comfort in the interior of the car.

  Furthermore, by using the method according to the invention, wiper blades with a resistant coating can be produced, so that a good wiping quality remains unchanged over a longer period of time, for example over a period corresponding to the inspection interval. Guaranteed.

  Using the method according to the invention, the crosslinking of the coating to reduce friction can be carried out at low temperatures, in particular after vulcanization of a basic shape made of a rubber-elastic material. Crosslinking can be carried out, for example, thermally at temperatures between 80 ° C. and 120 ° C. or by irradiation with ultraviolet light. In the latter case in particular, the coating crosslinking takes place in seconds, which is positive in terms of wiper blade production time and in-line production of wiper blades.

The starting polymer can be a polyamide that is soluble in alcohol. In particular, a polyamide of the type —CO— (CH ₂ ) _x —NH— (x = 3 to 20), —CO— (CH ₂ ) _x —CO—NH— (CH ₂ ) _y —NH— (x, y = 3-20) type polyamides or copolyamides with any organic group between amide functional groups.

In an advantageous configuration of the process according to the invention, the side chains are arranged such that some of the protons of the nitrogen atom of the amide function are replaced by organic groups of the structure —CH ₂ —O—R, R is any organic group having at least one carbon / carbon / double bond.

  The organic group R can be, for example, in each case one vinyl group or an allyl group. However, the organic group R may be another suitable group that is crosslinked in a subsequent method step.

  The side chain can be, for example, in each case an allyloxymethyl group or an acrylate or methacrylate group. Particularly advantageous is the introduction of side chains having carbon, carbon and double bonds.

  In principle, the functionality of the organic group R is not limited to carbon, carbon and double bonds. Rather, the side chain can have a different functional group each time.

  The introduction of the side chains weakens the hydrogen crosslinks between the polymer chains, so that the modification results in a polyamide that is soluble in alcohol, for example, and the basic shape is covered by this polyamide. Alcohol-soluble coatings are crosslinked to yield insoluble polymers upon crosslinking. When the polyamide is crosslinked in this way, it exhibits a low friction value against the glass and at the same time is abrasion resistant.

  Advantageously, 2% to 100% of the amide functionality of the polyamide is replaced with side chains.

  Alcohols, water and / or organic acids can be used as solvents for the modified starting polyamide. However, other suitable organic compounds and mixtures thereof can also serve as the solvent.

  In some cases, the wiper blade additionally comprises a portion of the amide functionality of the starting polymer in terms of the resulting friction value, additionally comprising 1 to 20 carbon atoms and at least one fluorine atom. It may be advantageous to substitute with different organic groups. For this purpose, for example, fluorinated alcohols are suitable. Thereby, by the use of suitable starting compounds, polyfluorinated side chains and perfluorinated side chains are introduced into the polymer, advantageously affecting the properties of the polymer. Fluorinated surfaces are generally anti-tack and water repellent and have a low friction value against glass.

  Furthermore, lubricant particles can be added to the polymer solution to further reduce the friction value, the particle size of the lubricant particles being 0.01 μm to 50 μm, preferably smaller than 10 μm. Suitable lubricant particles comprise, for example, Teflon (polytetrafluoroethylene), polyethylene, polyethylene UHMW, polyamide and / or silicon dioxide.

  Monomers with at least two carbon, carbon and double bonds that modify the cross-linking of the polymer chain may be added to the polymer solution.

  However, the polymer solution has one or two carbon / carbon / double bonds which, when crosslinked, crosslink with the unsaturated side chain of the polymer and have at least one fluorine atom and / or at least one silicon atom. Compounds may be added.

  The invention is also directed to a windshield wiper wiper blade having a basic shape made of a rubber-elastic material, the basic shape being at least partially provided with a coating that reduces friction. The friction reducing coating is formed from a modified polymer, which has unsaturated side chains that are crosslinkable.

  This type of wiper blade has a low dry friction value for glass and can be manufactured inexpensively and without damaging the material.

  Further advantages and advantageous configurations of the subject of the invention can be found in the description of the examples, the drawings and the claims.

The embodiment of the wiper blade according to the invention is shown schematically in a simplified manner in the drawing and is described in detail below. The only drawing is a cross-sectional view of the windshield wiper wiper blade.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing, a wiper blade 10 is shown, which has good sliding properties with respect to glass and is made of a rubber material, with a wiper lip 12 with a wiper edge 11, and rubber. It has a head portion 13 made of material, here only partially shown, and a “tilting web” 14 made of rubber material, which is arranged between the head portion 13 and the wiper lip 12. ing.

  The wiper lip 12, the head portion 13 and the tilted web 14 are provided with a coating 15, which serves to reduce the dry friction value of the wiper blade 10, and for the sake of clarity, the wiper lip 12, the head portion 13 are provided. In addition, the enlarged web 14 is shown in comparison with the tilted web 14. The coating 15 preferably consists of a cross-linked allyloxymethyl polyamide.

  Fabrication of the illustrated wiper blade 10 is performed as described below.

  In order to manufacture the wiper blade 10, a basic shape or substrate is first manufactured from an elastomer starting material such as natural rubber, chloroprene rubber, silicone rubber or polyurethane rubber by extrusion, and the basic shape or substrate is a wiper lip 12, It has a tilted web 14 and a head portion 13. The substrate is vulcanized and then subjected to a cleaning process.

  Subsequently, the substrate is coated with a polymer solution, the polymer solution having a modified polyamide in the form of allyloxymethyl polyamide, where some of the amide functional groups of the polyamide have unsaturated side chains. This side chain is crosslinkable.

  The wiper blade or wiper rubber profile is then coated with the polymer solution by dipping, spraying or brushing and exposed to a temperature of 120 ° C. for a duration of 5 minutes, so that the solvent evaporates and The coating is crosslinked by thermal means to form an elastic, solvent-insoluble polymer film. The polymer film adheres well to a substrate made of an elastomer.

  The drying of the coated polymer system is carried out in an air circulation oven (Umluftofen) by infrared radiation or by the action of microwaves. Crosslinking of the polymer system can be carried out by heat during drying or by UV light, light, infrared radiation or another suitable electromagnetic radiation.

  After crosslinking, the wiper rubber can be cut to the desired dimensions.

  The allyloxymethyl polyamide used in the illustrated embodiment is excellent in terms of its good crosslinkability, and is deposited and crosslinked on a substrate under conditions that do not damage the rubber material of the wiper blade. On the other hand, in polyamides that have been used for wiper blades so far, extremely high temperatures are required for crosslinking, so the polyamide must be deposited on the substrate before vulcanization. Requires considerable production skill.

  The allyloxymethyl polyamide used in this case is produced, for example, as described below.

  First, 6 g of polyamide 6.6 is dissolved in 90% formic acid at 60 ° C. while stirring. At the same time, 6 g of paraformaldehyde is dissolved in 11.6 g of allyl alcohol together with about 0.1 g of solid potassium hydroxide while heating to a clear solution.

  This clear and warm solution is added to the dissolved polyamide. This is done at a temperature of about 60 ° C. In this case, the temperature should not exceed 65 ° C. The addition is first slow and then slightly faster, so that the total amount of solution has been added to the dissolved polyamide after about 4 minutes.

Advantageously, 11.6 g of allyl alcohol are added 11 minutes after the start of the addition. The mixture is then stirred at a temperature of 60 ° C. for a duration of 40 minutes. The solution thus made is subsequently added to a mixture of acetone and water containing acetone and water in a ratio of 1: 1 and slowly neutralized with ammonia NH ₃ while stirring. Here, the polyamide in the modified state precipitates, and is then filtered off and dried.

  The dried polyamide is dissolved in ethanol under the influence of heat and then cooled. Thereafter, about 5% by weight of a radical initiator, such as azoisobutyronitrile AIBN, is added to the cooled solution.

  The wiper rubber profile coated with this solution has a dry friction value against glass of about 1.0 to 1.2 after drying and crosslinking, is wear resistant and is sufficient as a wiper blade Chemical stability.

It is a cross-sectional view of the windshield wiper wiper blade.

Claims (12)

  In a method of manufacturing a windshield wiper wiper blade, wherein a friction reducing coating (15) is applied, at least in part, on a substrate (12, 13, 14) made of a rubber elastic material. The coating (15) is made from a polymer solution, to which is added a monomer with at least two carbon, carbon and double bonds that modifies the crosslinking of the polymer, the polymer solution being crosslinkable A wiper blade, characterized in that it contains a starting polymer that has been modified by having unsaturated side chains that are and that the modified starting polymer is crosslinked after application to a basic shape How to make.   The process of claim 1 wherein the starting polymer is a polyamide. _{3. The} side chain has an organic group having a structure of —CH ₂ —O—R, and R is an arbitrary organic group having at least one carbon / carbon / double bond. the method of.   4. The process as claimed in claim 1, wherein alcohols and / or organic acids are used as solvents for the modified starting polymer.   Add to the polymer solution a compound with one or two carbon / carbon / double bonds that has at least one fluorine and / or silicon atom and crosslinks with unsaturated side chains when the polymer is crosslinked The method according to any one of claims 1 to 4. A windshield wiper wiper blade is provided with a base (12, 13, 14) made of a rubber-elastic material, which reduces friction at least partially on the base (12, 13, 14). In the type in which the coating is provided, the friction reducing coating (15) is formed from a modified polymer, the polymer having unsaturated side chains that are crosslinkable; The side chain has an organic group having a structure of —CH ₂ —O—R, and R is any organic group having at least one carbon / carbon / double bond, Windshield wiper wiper blade.   The wiper blade of claim 6, wherein the modified polymer is a polyamide.   The wiper blade according to claim 6 or 7, wherein the unsaturated side chain has a vinyl group or an allyl group.   The wiper blade according to claim 7, wherein 2% to 100% of the amide functional groups of the polyamide are substituted with side chains. 10. A wiper blade according to claim 9 , wherein a part of the amide functional group is additionally substituted with an organic group, the organic group having 1 to 20 carbon atoms and at least one fluorine atom.   Wiper blade according to any one of claims 6 to 10, wherein the coating (15) has lubricant particles with a particle size of less than 50 µm, preferably less than 10 µm.   The wiper blade according to any one of claims 6 to 11, wherein the production of the wiper blade is carried out according to the method according to any one of claims 1 to 5.

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