Wiper blade rubber and manufacturing method therefor

Abstract

To provide a wiper blade rubber excellent in wiping performance.SOLUTION: A wiper blade rubber 10 is formed of a crosslinked rubber composition. The wiper blade rubber 10 includes a contact sliding portion 12 that slides in contact with a surface of another member. A surface of the contact sliding portion 12 is subjected to chlorination treatment. A ratio of an amount of increase in chlorine element concentration due to the chlorination treatment in a portion from the surface of the contact sliding portion 12 to a depth of 1 μm to an amount of increase in chlorine element concentration due to the chlorination treatment in a portion from the depth of 1 μm to a depth of 2 μm is 1.5 or more and 4.0 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wiper blade rubber and a method for manufacturing the same. [Background technology]

[0002] There is a known technique for modifying the surface of wiper blade rubber by subjecting the surface to a chlorination treatment. For example, Patent Documents 1 and 2 disclose wiper blades that have been subjected to a chlorination treatment to set the chlorine concentration on the surface to 1.0 mass % or more and 2.5 mass % or less. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-64281 [Patent Document 2] Patent No. 6018832 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a wiper blade rubber having excellent wiping performance. [Means for solving the problem]

[0005] The present invention provides a wiper blade rubber that includes a contact sliding part that contacts and slides on the surface of another member and is formed of a crosslinked rubber composition, wherein the surface of the contact sliding part is subjected to a chlorination treatment, and the ratio of the increase in chlorine element concentration due to the chlorination treatment in a portion from the surface of the contact sliding part to a depth of 1 μm to the increase in chlorine element concentration due to the chlorination treatment in a portion from a depth of 1 μm to a depth of 2 μm is 1.5 or more and 4.0 or less.

[0006] The present invention is a method for manufacturing a wiper blade rubber of the present invention, which comprises preparing a blade rubber body formed from a crosslinked rubber composition, subjecting the blade rubber body to a wet chlorination treatment, and in the chlorination treatment, immersing the blade rubber body in a chlorination treatment aqueous solution having a chlorine concentration of 100 ppm or more and 800 ppm or less, immersing the blade rubber body in cleaning water after removing it from the chlorination treatment aqueous solution to wash it, immersing the blade rubber body in warm water after removing it from the cleaning water to wash it, and drying the blade rubber body after removing it from the warm water. [Effects of the Invention]

[0007] According to the present invention, the ratio of the increase in chlorine element concentration due to chlorination treatment in the portion from the surface of the contact sliding part to a depth of 1 μm to the increase in chlorine element concentration due to chlorination treatment in the portion from a depth of 1 μm to a depth of 2 μm is 1.5 or more and 4.0 or less, thereby achieving excellent wiping properties. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view of a piece of wiper blade rubber according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The embodiments will be described in detail below.

[0010] FIG. 1 shows a wiper blade rubber 10 according to an embodiment.

[0011] The wiper blade rubber 10 according to the embodiment is a long, thin rubber part having a roughly flat plate shape, and has an attachment holding portion 11 on one side in the width direction, a lip portion 12 on the other side in the width direction, and a neck portion 13 connecting the attachment holding portion and the lip portion.

[0012] In the wiper blade rubber 10 according to the embodiment, the attachment holder 11 is attached to a vertebra of a wiper drive unit provided on the underside of the windshield of an automobile, for example, and when the wiper drive unit is driven, the lip portion 12 tilts with the neck portion 13 as a fulcrum and contacts and slides against the surface of the windshield to wipe away rain, etc. Therefore, the lip portion 12 (particularly the edge portion 14 at its tip) constitutes the contact sliding portion with other members.

[0013] The wiper blade rubber 10 according to the embodiment is formed of a crosslinked rubber composition containing a rubber component and a rubber compounding agent.

[0014] Examples of rubber components include natural rubber (NR), chloroprene rubber (CR), ethylene propylene diene rubber (EPDM), and styrene butadiene rubber (SBR). Examples of CR include sulfur-modified, mercaptan-modified, and xanthogen-modified types. The rubber component preferably contains one or more of these, and from the viewpoint of obtaining excellent wiping properties, a blend rubber containing NR and CR is preferably used.

[0015] When the rubber component is a blend rubber containing NR and CR, the NR content is preferably greater than the CR content from the viewpoint of obtaining excellent wiping performance. From the same viewpoint as above, the mass ratio of the NR content to the CR content is preferably greater than 35 / 65, more preferably 40 / 60 or more, and preferably 70 / 30 or less, more preferably 65 / 35 or less.

[0016] Examples of rubber compounding agents include carbon black, vulcanization accelerators, processing aids, vulcanization accelerators, and antioxidants.

[0017] Examples of carbon black include channel black, furnace black, thermal black, and acetylene black. Examples of furnace black include SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, and N-234. Examples of thermal black include FT and MT. It is preferable that the carbon black contains one or more of these.

[0018] The nitrogen adsorption specific surface area of ​​the carbon black is preferably 20 m from the viewpoint of obtaining excellent wiping properties. 2 / g or more 50m 2 / g or less, more preferably 25m 2 / g or more 45m 2 / g or less. From the viewpoint of obtaining excellent wiping properties, the arithmetic mean particle size of the carbon black is preferably 35 nm or more, more preferably 40 nm or more, and preferably 100 nm or less, more preferably 70 nm or less.

[0019] From the viewpoint of obtaining excellent wiping properties, the content of carbon black in the crosslinked rubber composition is preferably 20 parts by mass or more and 34 parts by mass or less, more preferably 22 parts by mass or more and 33 parts by mass or less, and even more preferably 24 parts by mass or more and 32 parts by mass or less, per 100 parts by mass of the rubber component. Note that the content in the crosslinked rubber composition in the present application means the amount blended into the uncrosslinked rubber composition before crosslinking of the crosslinked rubber composition.

[0020] Examples of the vulcanization accelerator aid include metal oxides such as zinc oxide (zinc white) and magnesium oxide, metal carbonates, fatty acids, and derivatives thereof. The vulcanization accelerator aid preferably contains one or more of these, and from the viewpoint of obtaining excellent wiping properties, it is more preferable to contain a metal oxide, even more preferable to contain zinc oxide and / or magnesium oxide, and even more preferable to contain both zinc oxide and magnesium oxide. When the rubber component contains CR and the vulcanization accelerator aid contains a metal oxide, the metal oxide also acts as a crosslinking agent for the CR.

[0021] The content of the vulcanization accelerator aid in the crosslinked rubber composition is preferably 5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component, from the viewpoint of obtaining excellent wiping properties.

[0022] Examples of processing aids include stearic acid, polyethylene wax, and metal salts of fatty acids. The processing aid preferably contains one or more of these, and from the viewpoint of obtaining excellent wiping properties, it is more preferable that the processing aid contains stearic acid. From the same viewpoint as above, the content of the processing aid in the crosslinked rubber composition is preferably 0.5 parts by mass or more and 1.5 parts by mass or less per 100 parts by mass of the rubber component.

[0023] Examples of the vulcanization accelerator include sulfenamide-based vulcanization accelerators, thiourea-based vulcanization accelerators, aldehyde-ammonia-based vulcanization accelerators, aldehyde-amine-based vulcanization accelerators, guanidine-based vulcanization accelerators, thiazole-based vulcanization accelerators, thiuram-based vulcanization accelerators, dithiocarbamate-based vulcanization accelerators, etc. It is preferable that the vulcanization accelerator contains one or more of these.

[0024] The content of the vulcanization accelerator in the crosslinked rubber composition is preferably 2 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the rubber component, from the viewpoint of obtaining excellent wiping properties.

[0025] Examples of the antioxidant include p-phenylenediamine-based antioxidants, diphenylamine-based antioxidants, amine-ketone-based antioxidants, monophenol-based antioxidants, bisphenol-based antioxidants, polyphenol-based antioxidants, benzimidazole-based antioxidants, dithiocarbamate-based antioxidants, phosphorous-based antioxidants, organic thioacid-based antioxidants, etc. The antioxidant may contain one or more of these.

[0026] From the viewpoint of obtaining excellent wiping properties, the crosslinked rubber composition is preferably crosslinked using sulfur as a crosslinking agent. In this case, from the same viewpoint as above, the amount of sulfur blended into the uncrosslinked rubber composition is preferably 1 part by mass or more and 4 parts by mass or less per 100 parts by mass of the rubber component. Note that the crosslinked rubber composition may be crosslinked using an organic peroxide as a crosslinking agent.

[0027] In the wiper blade rubber 10 according to the embodiment, the entire surface is subjected to a chlorination treatment.

[0028] The amount S of chlorine added by chlorination treatment on the surface of the lip portion 12, which constitutes the sliding contact portion with other members, is preferably 0.5% by mass or more and 3.5% by mass or less, more preferably 1.0% by mass or more and 3.0% by mass or less, from the viewpoint of obtaining excellent wiping performance. In the present application, the amount S of chlorine added is determined by measuring the chlorine element concentration of all elements on the surface of the lip portion 12 through elemental analysis by X-ray fluorescence analysis of the surface of the lip portion 12, and also measuring the chlorine element concentration of an unchlorinated product as a control in the same manner, and then subtracting the chlorine element concentration of the latter from the former.

[0029] From the viewpoint of obtaining excellent wiping performance, the increase A in the elemental chlorine concentration due to the chlorination treatment in the portion from the surface to a depth of 1 μm of the lip portion 12 is preferably 2% by mass to 9% by mass, more preferably 3% by mass to 7% by mass. In the present application, the increase A in the elemental chlorine concentration is determined by measuring the elemental chlorine concentration of all elements in a portion of a predetermined width (for example, 40 μm) from the surface of the lip portion 12 to a depth of 1 μm through elemental analysis by scanning electron microscope energy dispersive X-ray spectroscopy (SEM-EDX) of the cross section of the lip portion 12, and also measuring the elemental chlorine concentration of an unchlorinated product as a control, and then subtracting the elemental chlorine concentration of the latter from the former.

[0030] The increase in chlorine element concentration B due to the chlorination treatment in the portion from the surface of the lip portion 12 to a depth of 1 μm to 2 μm is preferably 1 mass % or more and 6 mass % or less, more preferably 2 mass % or more and 4 mass % or less, from the viewpoint of obtaining excellent wiping performance. This increase in chlorine element concentration B is also determined in the same manner as the increase in chlorine element concentration A.

[0031] The increase C in elemental chlorine concentration due to chlorination treatment in the portion from the surface of the lip portion 12 to a depth of 2 μm to 3 μm is preferably 0.3 mass% or more and 3 mass% or less, more preferably 0.5 mass% or more and 2 mass% or less, from the viewpoint of obtaining excellent wiping performance. This increase C in elemental chlorine concentration is also determined in the same manner as the increase A in elemental chlorine concentration and the increase B in elemental chlorine concentration.

[0032] The ratio of the chlorine element concentration increase amount A to the chlorine element concentration increase amount B (chlorine element concentration increase amount A / chlorine element concentration increase amount B, hereinafter referred to as "concentration increase amount ratio X") is 1.5 or more and 4.0 or less. According to the wiper blade rubber 10 according to the embodiment, since the concentration increase amount ratio X is 1.5 or more and 4.0 or less, excellent wiping performance can be obtained. From the viewpoint of obtaining excellent wiping performance, the concentration increase amount ratio X is preferably 1.5 or more and 4.0 or less, more preferably 1.6 or more and 2.3 or less.

[0033] The ratio of the chlorine element concentration increase amount A to the chlorine element concentration increase amount C (chlorine element concentration increase amount A / chlorine element concentration increase amount C, hereinafter referred to as "concentration increase amount ratio Y") is preferably 2.0 or more and 7.0 or less, more preferably 3.0 or more and 5.0 or less, from the viewpoint of obtaining excellent wiping performance.

[0034] The wiper blade rubber 10 according to the embodiment can be manufactured by preparing an uncrosslinked rubber composition by compounding and kneading a rubber compounding agent containing carbon black and a crosslinking agent with a rubber component, molding and crosslinking this uncrosslinked rubber composition to produce a blade rubber body formed of the crosslinked rubber composition, and then subjecting this blade rubber body to a wet chlorination treatment.

[0035] Examples of methods for molding the blade rubber body include press molding, extrusion molding, injection molding, and transfer molding.

[0036] In wet chlorination treatment, the blade rubber body is first immersed in a chlorine-containing chlorination treatment solution, such as an aqueous solution of hypochlorous acid or a hypochlorite (e.g., calcium hypochlorite or sodium hypochlorite) to which an acid such as hydrochloric acid is added to lower the pH, thereby generating chlorine.

[0037] The chlorine concentration in the chlorination treatment aqueous solution is preferably 100 ppm to 800 ppm, more preferably 150 ppm to 700 ppm. The pH of the chlorination treatment aqueous solution is preferably 1.5 to 2.4, more preferably 1.8 to 2.3.

[0038] Next, the blade rubber body is taken out of the chlorination treatment aqueous solution and washed by immersing it in washing water to effectively stop the chlorination reaction.

[0039] Next, the blade rubber body is removed from the cleaning water and immersed in warm water for cleaning.

[0040] The blade rubber body is then removed from the warm water and dried to obtain the wiper blade rubber 10.

[0041] In the above embodiment, the entire surface of the wiper blade rubber 10 is chlorinated, but this is not limited to this, and it is sufficient that the chlorination treatment is applied to at least the surface of the lip portion 12 that constitutes the contact sliding portion with other components. [Example]

[0042] (Wiper blade rubber) The wiper blade rubbers of Examples 1 and 2 and Comparative Example were produced with the same configuration as the above embodiment. The configurations of each are also shown in Tables 1 and 2.

[0043] Example 1 A blend rubber mixed at a mass ratio of NR / CR = 40 / 60 was used as the rubber component, and FEF (nitrogen adsorption specific surface area: 42 m) was used for 100 parts by mass of this rubber component. 2 An uncrosslinked rubber composition was prepared by blending and kneading 30 parts by mass of 100% cellulose ester (cellulose acetate / g, arithmetic mean particle size: 43 nm) and the types and amounts of other additives as shown in Table 1. This uncrosslinked rubber composition was press-molded and crosslinked to prepare a blade rubber body, which was then subjected to a wet chlorination treatment.

[0044] Specifically, in the chlorination treatment, the blade rubber body was first immersed in a chlorination treatment aqueous solution. The chlorination treatment aqueous solution was an aqueous solution in which chlorine was generated by adding hydrochloric acid to a calcium hypochlorite aqueous solution to lower the pH to 1.8. The chlorine concentration in the chlorination treatment aqueous solution was set to 200 ppm. The blade rubber body was immersed in the chlorination treatment aqueous solution.

[0045] The blade rubber body was then removed from the chlorination treatment solution, immersed in cleaning water, and then in warm water for washing.The blade rubber body was then removed from the warm water and placed in an oven to dry.

[0046] The wiper blade rubber obtained in this manner was designated as Example 1.

[0047] <Example 2> A wiper blade rubber was obtained in the same manner as in Example 1 except that the chlorine concentration in the chlorination treatment aqueous solution was set to 350 ppm in the chlorination treatment.

[0048] Example 3 A wiper blade rubber was obtained in the same manner as in Example 1 except that the pH of the aqueous chlorination solution in the chlorination treatment was set to 2.3, and designated Example 3.

[0049] Example 4 Example 4 was a wiper blade rubber obtained in the same manner as in Example 1, except that in the chlorination treatment, the pH of the chlorination treatment aqueous solution was 2.3 and the chlorine concentration was 350 ppm.

[0050] <Example 5> Example 5 was a wiper blade rubber obtained in the same manner as in Example 1, except that in the chlorination treatment, the pH of the chlorination treatment aqueous solution was 2.2 and the chlorine concentration was 300 ppm.

[0051] <Comparative Example> The chlorination treatment aqueous solution used was an aqueous solution in which chlorine was generated by adding hydrochloric acid to an aqueous solution of calcium hypochlorite to lower the pH to 2.3, and the chlorine concentration in the chlorination treatment aqueous solution was 770 ppm. A wiper blade rubber was obtained in the same manner as in Example 1, and designated Comparative Example 1.

[0052] [Table 1]

[0053] [Table 2]

[0054] (Test evaluation method and results) The wiper blade rubbers of Examples 1 to 5 and Comparative Example were subjected to the following test evaluations. The test results are shown in Table 3.

[0055] <Amount of chlorine added> For each of the wiper blade rubbers of Examples 1 to 5 and the Comparative Example, the chlorine concentration of all elements on the surface of the lip portion was measured by elemental analysis using fluorescent X-ray analysis. The chlorine concentration of a blade rubber body that had not been chlorinated was also measured in the same manner as a control. The difference between the chlorine concentration of the former and the chlorine concentration of the latter was calculated as the amount of chlorine added (S).

[0056] <Increase in chlorine element concentration> Elemental analysis was performed on each wiper blade rubber of Examples 1 to 5 and Comparative Example using scanning electron microscope energy dispersive X-ray spectroscopy (SEM-EDX). Elemental analysis was performed on a field image of the cross section of the lip portion revealed by freeze fracturing, magnified at 3000x magnification. A 40 μm wide and 1 μm long section was selected from the smooth portion near the surface of the lip portion, and the analysis was performed under conditions of an acceleration voltage of 10 kV and a measurement time of 30 seconds. The chlorine concentration was then measured from this elemental analysis. This elemental analysis was performed on each of seven layers, each of which was spaced 1 μm apart from the surface of the lip portion to a depth of 7 μm, with similar selection of a 40 μm wide and 1 μm long section. Furthermore, to determine the chlorine concentration in the portion not reached by the chlorination treatment, the chlorine concentration was measured in three sections at a depth of approximately 20 μm, and the average value was calculated. The difference between the average value and the chlorine concentration of each of the seven layers was used as the increase in the chlorine concentration of each layer. For each wiper blade rubber, the chlorine concentration was measured at three locations by elemental analysis, and the average of the increases in the chlorine concentration at the three locations for each layer was calculated and used as data. The increase in the chlorine concentration in the layer from the surface of the lip to a depth of 1 μm was defined as A, the increase in the chlorine concentration in the layer from the surface of the lip to a depth of 1 μm to 2 μm was defined as B, and the increase in the chlorine concentration in the layer from the surface of the lip to a depth of 2 μm to 3 μm was defined as C. A / B was calculated as the concentration increase ratio X, and A / C was calculated as the concentration increase ratio Y.

[0057] <Contact angle> A 100 mm long test specimen was cut from each wiper blade rubber of Examples 1 to 5 and the Comparative Example. The mounting and holding portion of the test specimen was attached to an elongated fixture, and the fixture with the test specimen attached was placed on a rotatable glass disk with a diameter of 400 mm, extending radially and with the tip of the lip portion of the test specimen abutting against it. A vertical load of 1.57 N was applied to the fixture to press the lip portion of the test specimen against the glass disk. Water was sprayed onto the glass disk to wet it, and the glass disk was rotated so that the speed at the center of the test specimen was 1.0 m / s, causing the test specimen to slide across the glass disk. At this time, the lip portion tilted relative to the glass disk, and the contact angle between the lip portion and the glass disk was measured.

[0058] <Static friction coefficient> For each of the wiper blade rubbers of Examples 1 to 5 and the Comparative Example, the frictional force was measured using a load cell attached to a fixture when measuring the contact angle. The maximum frictional force at the start of running was defined as the static frictional force, and this was divided by the normal load of 1.57 N to calculate the static friction coefficient.

[0059] <Vibration start voltage> The wiper blade rubbers of Examples 1 to 5 and the Comparative Example were mounted on an actual vehicle. Water was sprayed onto a water-repellent windshield, and the wiper drive motor was driven to wipe the water off the windshield with the wiper blade rubber. The drive voltage of the wiper drive motor was then gradually decreased by 1 V starting from 13 V, and the drive voltage at which the wiper blade rubber began to vibrate on the windshield was defined as the vibration start voltage.

[0060] <Wipeability> The wiper blade rubbers of Examples 1 to 5 and the Comparative Example were mounted on an actual vehicle. Water was sprayed onto the windshield to wet it, and the wiper drive motor was driven to wipe the water off the windshield with the wiper blade rubber. The wiping performance at this time was then evaluated on a 5-point scale as follows:

[0061] 5: No streaks or areas left behind. 4: 2-3 streaks remain or areas that disappear after wiping. 3: There are streaks or areas that have not been wiped off in areas that do not affect visibility. 2: There are streaks or areas that are not wiped away in areas where visibility is impaired. 1: There are streaks or areas that have not been wiped all over the surface.

[0062] [Table 3] [Industrial Applicability]

[0063] The present invention is useful in the technical field of wiper blade rubber and its manufacturing method. [Explanation of symbols]

[0064] 10 wiper blade rubber 11 Mounting holder 12 Lip part (contact sliding part) 13 Neck 14 Edge section

Claims

1. A wiper blade rubber including a contact sliding portion that contacts and slides on the surface of another member and is formed from a crosslinked rubber composition, The wiper blade rubber has a surface that has been subjected to a chlorination treatment, and the ratio of an increase in chlorine element concentration due to the chlorination treatment in a portion of the contact sliding portion from the surface to a depth of 1 μm to an increase in chlorine element concentration due to the chlorination treatment in a portion of the contact sliding portion from a depth of 1 μm to a depth of 2 μm is 1.5 or more and 4.0 or less.

2. The wiper blade rubber according to claim 1, The wiper blade rubber has a chlorine element concentration increase of 2% by mass or more and 9% by mass or less in a portion of the contact sliding portion from the surface to a depth of 1 μm due to the chlorination treatment.

3. The wiper blade rubber according to claim 1, The wiper blade rubber has a chlorine element concentration increase of 1% by mass or more and 6% by mass or less in a portion of the contact sliding portion from a surface of 1 μm to a depth of 2 μm due to the chlorination treatment.

4. The wiper blade rubber according to claim 1, The wiper blade rubber has a chlorine element concentration increase of 1% by mass or more and 3% by mass or less due to the chlorination treatment in a portion of the contact sliding portion from a surface of 2 μm to a depth of 3 μm.

5. The wiper blade rubber according to claim 1, a wiper blade rubber in which the ratio of the increase in chlorine element concentration due to the chlorination treatment in a portion from the surface of the sliding contact part to a depth of 1 μm to the increase in chlorine element concentration due to the chlorination treatment in a portion from the surface of the sliding contact part to a depth of 2 μm to 3 μm is 2.0 or more and 7.0 or less.

6. The wiper blade rubber according to claim 1, The wiper blade rubber has a chlorine content of 0.5% by mass or more and 3.5% by mass or less on the surface of the sliding contact portion due to the chlorination treatment.

7. The wiper blade rubber according to claim 1, The wiper blade rubber comprises a rubber component of the crosslinked rubber composition, which is a blend rubber containing natural rubber and chloroprene rubber.

8. A method for manufacturing the wiper blade rubber according to any one of claims 1 to 7, A blade rubber body is prepared from a crosslinked rubber composition, and the blade rubber body is subjected to a wet chlorination treatment; In the chlorination treatment, the blade rubber body is immersed in a chlorination treatment aqueous solution having a chlorine concentration of 100 ppm or more and 800 ppm or less, the blade rubber body is removed from the chlorination treatment aqueous solution and immersed in cleaning water to wash it, the blade rubber body is removed from the cleaning water and immersed in warm water to wash it, and the blade rubber body is removed from the warm water and dried.

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