Wiper blade rubber

Abstract

The polymer is a blended rubber containing natural rubber and chloroprene rubber, and is made of a rubber composition containing carbon black. At least the lip portion (12) is provided with a coating layer (14) of a fixed lubricant. The coating layer contains a binder and a fixed lubricant, has a thickness of 1.5 μm to 5 μm, the proportion of the portion not covered by the fixed lubricant is 1% or less of the total surface area of ​​the coating layer on the lip portion, and the maximum void size of one uncovered portion of the coating layer is 600 μm. 2 It is smaller than that. This prevents an increase in the coefficient of friction when semi-dry, suppressing the generation of abnormal noises as it dries.

Description

[Technical Field]

[0001] This invention relates to wiper blade rubber used in automobile windshields and the like. [Background technology]

[0002] Conventionally, as shown in Patent Document 1, for example, a wiper blade rubber having a lip portion with a coating layer applied by spray coating to a rubber substrate is known, in which the coating layer, when observed on the spray-coated surface, consists of a portion that covers the rubber substrate and a portion that does not cover the rubber substrate, and the portion that does not cover the rubber substrate consists of multiple holes with a diameter of 10 μm to 40 μm that are evenly formed throughout the entire surface of the coating layer without any significant bias, and these holes penetrate from the surface in contact with the rubber substrate to the outer surface of the coating layer, and the ratio of the total area of ​​the portion that covers the rubber substrate to the total area of ​​the portion that does not cover the rubber substrate is known to be 40:60 to 60:40.

[0003] This blade rubber design incorporates areas that are not covered by the rubber base material, thereby suppressing bleed-out from the rubber base material and the occurrence of blistering (blistering) of the coating layer due to bloom. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 6937307 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, in the wiper blade rubber of Patent Document 1, the proportion of the area not covered by the rubber base material is high, which can increase the coefficient of friction when semi-dry, and cause abnormal noise as it dries. For example, when driving in the rain and the wipers are activated, if the vehicle enters a tunnel, the rainwater will disappear from the wiped area of ​​the wiper blade rubber after several wipes. However, as the rainwater is almost gone, the wiper blade rubber will activate, causing abnormal noise and discomfort to the occupants.

[0006] This disclosure has been made in view of the above, and its purpose is to prevent an increase in the coefficient of friction during semi-drying and to suppress the generation of abnormal noise as the surface dries. [Means for solving the problem]

[0007] To achieve the above objectives, this disclosure adjusts the ratio of the portion of the lip that is not covered by the solid lubricant coating layer.

[0008] Specifically, in the first embodiment, The polymer is a blend of rubber containing natural rubber and chloroprene rubber, and consists of a rubber composition containing carbon black. At least the lip portion is provided with a solid lubricant coating layer. The aforementioned coating layer is Binder and, Includes a solid lubricant, The thickness is 1.5 μm or more and 5 μm or less. The proportion of the portion not covered by the solid lubricant is 1% or less of the total area of ​​the coating layer in the lip portion. The maximum void size at one point in the coating layer that is not covered by the solid lubricant is 600 μm. 2 It is smaller than that.

[0009] Here, if the coating layer is thinner than 1.5 μm, abnormal noises are more likely to occur as it dries, and if it is thicker than 5 μm, the wiping performance after durability deteriorates.

[0010] If the maximum void size is 600 μm or more, abnormal noise is likely to occur during drying. 2 When the ratio of the portion not covered with the solid lubricant is greater than 1% with respect to the total area of the coating layer at the lip portion, abnormal noise occurs during drying.

[0011] However, according to the above configuration, by appropriately maintaining the thickness of the coating layer and appropriately maintaining the ratio of the portion not covered with the solid lubricant and the maximum void size in the coating layer, a wiper blade rubber that can prevent an increase in the friction coefficient during semi-dry and suppress the occurrence of abnormal noise during drying can be obtained.

[0012]

[0013] In a second aspect, in the first aspect, the binder is thermoplastic polyurethane, the solid lubricant is artificial graphite powder.

[0014] According to the above configuration, a coating layer with stable quality that is difficult to peel off can be obtained.

[0015] In a third aspect, in the first or second aspect, the average particle diameter of the artificial graphite powder of the solid lubricant is 10 μm or less.

[0016] According to the above configuration, the ratio of the portion not covered with the solid lubricant becomes 1% or less, but when it exceeds 10 μm, it exceeds 1% and abnormal noise occurs during drying.

Advantages of the Invention

[0017] As described above, according to the present disclosure, it is possible to prevent an increase in the friction coefficient during semi-dry and suppress the occurrence of abnormal noise during drying.

Brief Description of the Drawings

[0018] [Figure 1] It is a perspective view showing the appearance of a wiper blade rubber. [Figure 2] This is a magnified photograph of the surface when the proportion of the area not covered by the solid lubricant is 1% or less of the total surface area of ​​the coating layer on the lip. [Figure 3] This is a magnified photograph of the surface when the proportion of the area not covered by the solid lubricant is greater than 1% of the total surface area of ​​the coating layer on the lip. [Modes for carrying out the invention]

[0019] The embodiments of this disclosure will be described below with reference to the drawings.

[0020] Figure 1 shows a wiper blade rubber 10 according to an embodiment. This wiper blade rubber 10 is a generally flat, elongated rubber component, with a mounting and holding portion 11 on one side in the vertical direction and a lip portion 12 on the other side in the vertical direction, and a neck portion 13 connecting the mounting and holding portion and the lip portion 12. At least the area of ​​the outer circumference of the lip portion 12 that contacts the glass surface is provided with a solid lubricant coating layer 14.

[0021] In this embodiment, the wiper blade rubber 10 has a mounting and holding portion 11 attached to the vertebra of a wiper drive unit provided, for example, on the lower side of the windshield of an automobile. When the wiper drive unit is driven, the portion of the lip portion 12 with the coating layer 14 tilts with the neck portion 13 as a pivot point and slides in contact with the surface of the windshield, thereby wiping away rain and the like.

[0022] The wiper blade rubber 10 according to this embodiment is formed from a crosslinked rubber composition containing a rubber component and a rubber compounding agent.

[0023] 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 type, mercaptan-modified type, and xanthogene-modified type. The rubber component preferably contains one or more of these, and a blended rubber containing NR and CR is more preferable from the viewpoint of obtaining excellent wipeability and sliding properties, as described later. When the rubber component is a blended rubber containing NR and CR, the NR content is preferably less than the CR content from the same viewpoint. From the same viewpoint, the mass ratio of the NR content to the CR content is preferably 30 / 70 or more and less than 50 / 50, more preferably 35 / 65 or more and 45 / 55 or less.

[0024] Examples of rubber compounding agents include carbon black, vulcanization accelerators, processing aids, vulcanization accelerators, and antioxidants.

[0025] 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 types. The carbon black content in the crosslinked rubber composition is, for example, 20 parts by mass or more and 40 parts by mass or less per 100 parts by mass of rubber component. In this application, the content in the crosslinked rubber composition refers to the amount of the crosslinked rubber composition blended into the uncrosslinked rubber composition before crosslinking.

[0026] Examples of vulcanization accelerators include metal oxides such as zinc oxide (zinc oxide) and magnesium oxide, metal carbonates, fatty acids and their derivatives. The vulcanization accelerator preferably contains one or more of these, and from the viewpoint of obtaining excellent wiping and sliding 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 contains a metal oxide, the metal oxide also acts as a crosslinking agent for CR. The content of the vulcanization accelerator in the crosslinked rubber composition is, for example, 3 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the rubber component.

[0027] 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 more preferably contains stearic acid from the viewpoint of obtaining excellent wiping and sliding properties. The content of the processing aid in the crosslinked rubber composition is, for example, 0.5 parts by mass or more and 1.5 parts by mass or less per 100 parts by mass of the rubber component.

[0028] Examples of vulcanization accelerators 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, thiram-based vulcanization accelerators, and dithiocarbamate-based vulcanization accelerators. It is preferable that the vulcanization accelerator contains one or more of these. The content of the vulcanization accelerator in the crosslinked rubber composition is, for example, 2 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the rubber component.

[0029] Examples of anti-aging agents include p-phenylenediamine-based anti-aging agents, diphenylamine-based anti-aging agents, amine-ketone-based anti-aging agents, monophenol-based anti-aging agents, bisphenol-based anti-aging agents, polyphenol-based anti-aging agents, benzimidazole-based anti-aging agents, dithiocarbamate-based anti-aging agents, phosphite-based anti-aging agents, and organic thioacid-based anti-aging agents. The anti-aging agent may contain one or more of these. The content of the anti-aging agent in the crosslinked rubber composition is, for example, 2 parts by mass or more and 6 parts by mass or less per 100 parts by mass of the rubber component.

[0030] From the viewpoint of obtaining excellent wiping and sliding properties, it is preferable that the crosslinked rubber composition is crosslinked using sulfur as the crosslinking agent. In this case, the amount of sulfur added to the uncrosslinked rubber composition is, for example, 1 to 4 parts by mass per 100 parts by mass of the rubber component. The crosslinked rubber composition may also be crosslinked using an organic peroxide as the crosslinking agent.

[0031] The coating agent for forming the coating layer comprises a solid lubricant and a binder for adhering the solid lubricant to the surface of the wiper blade rubber 10. The binder is prepared by mixing a urethane polymer with an organic solvent to a concentration of 1% by mass or less. The organic solvent may be ether-based, ketone-based, or ester-based, or a mixture thereof.

[0032] As a solid lubricant, artificial graphite powder (for example, UF-G5 manufactured by RESONAC) is used. UF-G5 has a fixed carbon content of 98.0% or more by mass, an ash content of 1.0% or less by mass, a particle size of 3 μm, and a specific surface area of ​​40 m². 2 It has a density of / g, contains fewer impurities than natural graphite, has stable quality, and provides high thermal conductivity, sliding properties, and lubricity that cannot be obtained with carbon black. It is desirable that the artificial graphite powder be contained in an amount of 2% to 7% by mass per 100% by mass of the organic solvent.

[0033] The organic solvent may be ether-based, ketone-based, or ester-based, but it is desirable that it contains a urethane prepolymer (e.g., thermoplastic polyurethane) for forming the binder in an amount of 1% by mass or less per 100% by mass of the organic solvent. An example of thermoplastic polyurethane is BASF's 119ATR.

[0034] -Coating Method- A graphite coat layer was formed on the coating layer 14 by spraying the coating agent onto the contact sliding portions on both sides of the tandem molded body using a spray nozzle. At this time, the thickness of the graphite coat layer, the base material ratio, and the maximum area of ​​the uncoated portion were controlled by varying the combination of the relative movement speed between the spray nozzle and the tandem molded body and the number of coats applied.

[0035] -Coating film thickness measurement- In a test specimen of the wiper blade rubber 10, the tip sliding portion of the lip portion 12 was observed with a video microscope at 1000x magnification, and the thickness of the coating layer 14 formed on the tip sliding portion was measured.

[0036] - Measurement of base material ratio - The surface of coating layer 14 was observed using a video microscope at 1000x magnification. Areas with a height of 0.5 μm or less were considered the substrate, and areas greater than 0.5 μm were considered the coated area. The area ratio of the uncoated substrate was calculated as the substrate ratio. Areas consisting only of binder and lacking graphite, with a height of 0.5 μm or less, were also recognized as the substrate.

[0037] -Durability Wipe Test- The wiper blade rubber 10 was tested in accordance with the procedure described in JIS D 5710. The wiper blade rubber 10 was installed in its normal operating condition, and water was uniformly sprayed onto the glass surface at an ambient temperature of 20±15℃, a water temperature of 38℃ or less, with a water flow rate of 800 ml / min or more. The wiper was then operated 500,000 times at a reciprocating speed of 45 times / minute or more, and the number of streaks left behind was checked.

[0038] If the number of remaining residues was less than that specified in JIS D 5710, it was marked as ○; if the number of remaining residues exceeded the specified number, it was marked as ×.

[0039] - Noise Evaluation - Similarly, in an actual vehicle, the arm pressure on the wiper arm to which the wiper blade rubber 10 was attached was set to 16 gf / cm, and the wiper was driven for more than 5 minutes with a water spray rate of 800 ml / min or more. After 5 minutes, the water spray was stopped, the wiper was driven and made to move back and forth three times, and it was checked whether any abnormal noise occurred when it reversed direction.

[0040] If there was no unusual noise, it was marked as ○; if there was an unusual noise, it was marked as ×.

[0041] For Examples 1-6 and Comparative Examples 1-4, wiper blade rubbers were prepared with 10 different coating conditions (1-7), and the results of the measurements described above are shown in Table 1. The speeds for each application condition are shown as ratios, with the speed of Example 1 set to 1. The number of coating coats was also varied.

[0042] [Table 1]

[0043] <Example 1> Under coating conditions of speed 1 and 6 coating passes, the coating film thickness was 2.5 μm and the maximum uncoated area was 200 μm. 2 The average particle size of the graphite powder was set to 3 μm, and the substrate ratio (area ratio) was set to 0.4%. In Example 1, no abnormal noise was generated, and the durability wiping test was also successful.

[0044] <Example 2> Under coating conditions of speed 1 and 10 coating passes, the coating film thickness was 3.0 μm and the maximum uncoated area was 100 μm. 2 The average particle size of the graphite powder was set to 3 μm, and the substrate ratio (area ratio) was set to 0.3%. In Example 2, no abnormal noise was generated, and the durability wiping test was also successful.

[0045] <Example 3> Under the coating conditions of speed 1 and 2 coating times, the coated film thickness was 1.5 μm, the maximum area of the non-coated part was 400 μm 2 , the average particle diameter of the graphite powder was 3 μm, and the substrate ratio (area ratio) was 1.0%. Also in Example 3, no abnormal noise occurred and there was no problem in the durability wiping test.

[0046] <Example 4> Under the coating conditions of speed 1 / 3 and 5 coating times, the coated film thickness was 5.0 μm, the maximum area of the non-coated part was 20 μm 2 , the average particle diameter of the graphite powder was 3 μm, and the substrate ratio (area ratio) was 0.2%. Also in Example 4, no abnormal noise occurred and there was no problem in the durability wiping test.

[0047] <Example 5> Under the coating conditions of speed 1 and 6 coating times, the coated film thickness was 3.5 μm, the maximum area of the non-coated part was 310 μm 2 , the average particle diameter of the graphite powder was 5 μm, and the substrate ratio (area ratio) was 0.6%. Also in Example 5, no abnormal noise occurred and there was no problem in the durability wiping test.

[0048] <Example 6> Under the coating conditions of speed 1 and 6 coating times, the coated film thickness was 4.5 μm, the maximum area of the non-coated part was 530 μm 2 , the average particle diameter of the graphite powder was 10 μm, and the substrate ratio (area ratio) was 0.9%. Also in Example 6, no abnormal noise occurred and there was no problem in the durability wiping test. That is, there was no problem as long as the average particle diameter of the graphite powder was 10 μm or less.

[0049] <Comparative Example 1> Under the coating conditions of speed 1 / 3 and 2 coating times, the coated film thickness was 2.5 μm, the maximum area of the non-coated part was 600 μm 2 , the average particle diameter of the graphite powder was 3 μm, and the substrate ratio (area ratio) was 1.0%. In Comparative Example 1, although there was no problem in the durability wiping test, abnormal noise occurred.

[0050] <Comparative Example 2> Under the coating conditions of speed 1 and 1 coating time, the coated film thickness was 0.5 μm, the maximum area of the non-coated part was 800 μm 2The average particle size of the graphite powder was set to 3 μm, and the substrate ratio (area ratio) was set to 10.0%. In Comparative Example 2, abnormal noise was generated, and many areas were left unwiped during the durability wiping test.

[0051] <Comparative Example 3> Under coating conditions of speed 1 and 14 coating passes, the coating film thickness was 6.0 μm, and the maximum uncoated area was 10 μm. 2 The average particle size of the graphite powder was set to 3 μm, and the substrate ratio (area ratio) was set to 0.1%. In Comparative Example 3, although no abnormal noise was generated, many residues remained after wiping during the durability wiping test.

[0052] <Comparative Example 4> Under coating conditions of speed 1 and 6 coating passes, the coating film thickness was 7.0 μm, and the maximum uncoated area was 850 μm. 2 The average particle size of the graphite powder was set to 25 μm, and the substrate ratio (area ratio) was set to 3.2%. In Comparative Example 4, the particle size became 25 μm, making it difficult to lay the material without gaps, resulting in a larger area ratio and the generation of abnormal noise. Furthermore, the film thickness also increased, resulting in many residues remaining even after wiping following the durability test.

[0053] As can be seen from the comparison between the examples and comparative examples above, if the thickness of the coating layer is less than 1.5 μm, abnormal noises are more likely to occur when the coating is drying during inversion, and if it is thicker than 5 μm, durability decreases.

[0054] Maximum void size is 600 μm 2 As a result, abnormal noises are more likely to occur as the paint dries.

[0055] If the area ratio of the portion not covered by the fixing lubricant (base material ratio) is greater than 1% of the total area of ​​the coating layer on the lip portion, an abnormal noise will occur as it dries.

[0056] However, as shown in Examples 1 to 6, the thickness of the coating layer 14 is 1.5 μm or more and 5 μm or less, the proportion of the area not covered by flake-like graphite is 1% or less of the total area of ​​the coating layer 14 in the lip portion 12, and the maximum void size of one location in the area not covered by flake-like graphite in the coating layer 14 is 600 μm. 2 When the size is smaller than this, the thickness of the coating layer is kept at an appropriate level, and the proportion of the coating layer that is not covered by flaky graphite and the maximum void size are appropriately maintained, resulting in a wiper blade rubber that prevents an increase in the coefficient of friction when semi-dry and suppresses the generation of abnormal noise as it dries.

[0057] As explained above, this disclosure makes it possible to prevent an increase in the coefficient of friction during the semi-drying stage as the surface dries, thereby suppressing the generation of abnormal noises as the surface dries.

[0058] The embodiments described above are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or uses. [Explanation of Symbols]

[0059] 10 Wiper Blade Rubber 11 Mounting and holding part 12 Lip section 13. Neck section 14 Coating layer

Claims

1. The polymer is a blend of rubber containing natural rubber and chloroprene rubber, and consists of a rubber composition containing carbon black. At least the lip portion is provided with a solid lubricant coating layer. The aforementioned coating layer is Binder and, Includes a solid lubricant, The thickness is 1.5 μm or more and 5 μm or less. The proportion of the portion not covered by the solid lubricant is 1% or less of the total area of ​​the coating layer on the lip portion. The maximum void size at one point in the coating layer that is not covered by the solid lubricant is 600 μm. ２ Smaller than A wiper blade rubber characterized by the following features.

2. The binder is a thermoplastic polyurethane. The solid lubricant is artificial graphite powder. The wiper blade rubber according to feature 1.

3. The average particle size of the artificial graphite powder in the solid lubricant is 10 μm or less. The wiper blade rubber according to feature 1.

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