Wiper blade rubber

Abstract

When a tip end sliding section 11a is abutted against a glass surface of a glass disc 21 on a rotating disc testing machine and a load of 40 g / cm is applied during a condition in which the neck stiffness, which is the load immediately before a shoulder section 11b comes into contact with an attachment retention section 12, is 43 mN / cm to 67 mN / cm and the attachment retention section 12 is being retained, α2–α1 is 7 degrees to 30 degrees as viewed from the length direction of the wiper blade rubber, where α1 is the angle between a horizontal line La of the glass surface and a line Lb parallel to a straight portion of the tip end sliding section 11a, and α2 is the angle between the horizontal line La of the glass surface and a line Lc parallel a straight portion of a lip section 11, said straight portion being in an intermediate location that is further to the shoulder section 11b side than the tip end sliding section 11a. Thus, the production of an abnormal noise at the time of reversing direction is prevented by improving reversibility and causing the lip section to bend.

Description

Wiper blade rubber

[0001] The present invention relates to a wiper blade rubber used for windshields of automobiles and the like.

[0002] Conventionally, as disclosed in, for example, Patent Document 1, there has been known a blade rubber for wiping a window surface by reciprocating rocking of a wiper arm, wherein the blade rubber has a substantially constant cross-sectional shape in the longitudinal direction, and is configured to include an attachment holding portion for attaching to a lever body, a lip portion for wiping the window surface, and a neck portion for connecting the attachment holding portion and the lip portion.

[0003] In this blade rubber, at least the neck portion is cured by irradiation with a curing accelerating radiation source, and the curing treatment is varied in the longitudinal direction such that the portion corresponding to the support by the lever body has the largest absorbed dose, and the intermediate portion between adjacent support corresponding portions has the smallest absorbed dose, whereby the curing treatment with varied degree of cure is performed.

[0004] Japanese Patent No. 4890877

[0005] However, in the wiper blade rubber of Patent Document 1, since the curing treatment is varied in the longitudinal direction, the curing work is relatively troublesome.

[0006] The present disclosure has been made in view of the above point, and an object of the present disclosure is to prevent the generation of abnormal noise during reversal by improving reversal performance to allow the lip portion to bend.

[0007] In order to achieve the above object, in the present disclosure, the wiper blade rubber is configured to uniformly have a predetermined rigidity in the longitudinal direction.

[0008] Specifically, in the first embodiment, the subject is a wiper blade rubber having a triangular cross-section lip portion having a tip sliding portion that contacts and slides on the glass surface and a shoulder portion that gradually widens from the tip sliding portion, a mounting holding portion that is held by a wiper holding portion, and a thin-walled neck portion that connects the shoulder portion and the mounting holding portion. In this wiper blade rubber, in a surface performance measuring machine, the mounting holding portion of the wiper blade rubber cut to a predetermined length is held in a mounting jig, the mounting jig is moved at a speed of 10 mm / min relative to a load cell, the tip range of 10% of the lip length from the tip sliding portion to the shoulder portion is brought into contact with the load cell, and the neck stiffness, which is the load just before the shoulder portion contacts the mounting holding portion, is 43 mN / cm or more and 67 mN / cm or less, With the mounting and holding portion held, when the tip sliding portion is brought into contact with the glass surface of a glass on a rotating disc testing machine and a load of 40 g / cm is applied, the angle α1 between the horizontal line of the glass surface and the parallel line of the straight portion of the tip sliding portion, and the angle α2 between the horizontal line of the glass surface and the parallel line of the straight portion at an intermediate position on the shoulder side of the lip portion, are such that α2 - α1 is 7 deg or more and 30 deg or less.

[0009] If the neck stiffness is made less than 43 mN / cm, the lip becomes too soft, impairing its reversibility and generating abnormal noise. Conversely, if it is made more than 67 mN / cm, the lip becomes too hard, impairing its reversibility and generating abnormal noise. However, by keeping it between 43 mN / cm and 67 mN / cm, the generation of abnormal noise is suppressed without changing the neck stiffness in the longitudinal direction of the lip. Furthermore, if α2-α1 becomes less than 7 deg, the lip becomes hard, impairing its reversibility and generating abnormal noise. While it is difficult to make it greater than 30 deg due to constraints on the shape of the lip, keeping it between 7 deg and 30 deg allows for the suppression of abnormal noise with an appropriate lip shape. The surface properties measuring instrument is not particularly limited, but an example is the surface properties measuring instrument manufactured by Shinto Kagaku Co., Ltd.

[0010] In a second embodiment, the polymer is natural rubber or a blend of natural rubber and chloroprene rubber, and the rubber composition comprises carbon black.

[0011] According to the above configuration, a wiper blade rubber with excellent wiping properties can be obtained.

[0012] In a third embodiment, as in the second embodiment, at least the lip portion is provided with a graphite coating layer.

[0013] According to the above configuration, a wiper blade rubber with excellent wiping properties can be obtained.

[0014] In the fourth embodiment, as in the third embodiment, at least the lip portion has a chlorine-treated chlorine film of 1.0 μm to 2.0 μm thickness formed beneath the coating layer.

[0015] If the chlorine film thickness is less than 1.0 μm, the neck rigidity decreases, and if it is thicker than 2.0 μm, the neck rigidity becomes too high or the lip becomes too stiff. However, by setting the thickness to between 1.0 μm and 2.0 μm, an appropriate balance of neck rigidity and lip flexibility can be obtained.

[0016] In the fifth embodiment, in any one of the first to fourth embodiments, a tensile force is applied to stretch the material to 100%, and then the material is returned to 0%. This operation is repeated three times, and on the third repetition, the 30% modulus is 0.6 MPa or more and 1.2 MPa or less.

[0017] If the 30% modulus is less than 0.6 MPa, the reversal properties deteriorate, and if it is greater than 1.2 MPa, the reversal properties also deteriorate. However, if the modulus is between 0.6 MPa and 1.2 MPa, the reversal properties improve and water stagnation is less likely to occur.

[0018] As explained above, according to this disclosure, the reversal ability can be improved by increasing the neck rigidity of the wiper blade rubber, and the generation of abnormal noise during reversal can be suppressed by allowing the lip portion to flex appropriately.

[0019] This is a cross-sectional view showing the measurement of the contact angle of the wiper blade rubber. This is an enlarged front view of part II of Figure 3. This is a front view showing the measurement of the neck stiffness of the wiper blade rubber. This is a table comparing the embodiments and comparative examples of this disclosure.

[0020] The embodiments of this disclosure will be described below with reference to the drawings.

[0021] This is a cross-sectional view showing how the contact angle of the wiper blade rubber 10 is measured. The wiper blade rubber 10 is a generally flat, elongated rubber component, and has a triangular cross-section lip portion 11 having a tip sliding portion 11a that contacts and slides on the glass surface and a shoulder portion 11b that gradually widens from the tip sliding portion 11a, a mounting and holding portion 12 that is held by the wiper holding portion of a wiper arm (not shown), and a thin-walled neck portion 13 that connects the shoulder portion 11b and the mounting and holding portion 12.

[0022] In this embodiment, the wiper blade rubber 10 has a mounting and holding portion 12 that is attached to and held by a 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 lip portion 11 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.

[0023] 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.

[0024] 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 from the viewpoint of obtaining excellent wiping properties, a blended rubber containing NR and CR is preferably used.

[0025] When the rubber component is a blend rubber containing NR and CR, it is preferable that the NR content is greater than the CR content from the viewpoint of obtaining excellent wiping properties.

[0026] Examples of rubber compounding agents include carbon black, vulcanization accelerators, processing aids, vulcanization accelerators, and antioxidants.

[0027] 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.

[0028] The wiper blade rubber 10 according to this embodiment can be manufactured by preparing an uncrosslinked rubber composition by mixing a rubber compound containing carbon black and a crosslinking agent with the rubber component and kneading it, and then molding and crosslinking this uncrosslinked rubber composition. Examples of molding methods include press molding, extrusion molding, injection molding, and transfer molding.

[0029] In the wiper blade rubber 10 according to this embodiment, the entire surface is subjected to a chlorine treatment. From the viewpoint of obtaining a wiper blade rubber 10 with excellent wiping performance, a chlorine-treated chlorine film of 1.0 μm to 2.0 μm thickness is formed. The chlorine film only needs to be applied to at least the lip portion 11, but usually it is applied to most of the surface of the wiper blade rubber 10. The chlorine treatment may be carried out by treatment using, for example, bleaching powder or trichloroisocyanuric acid.

[0030] In the wet chlorination method, the blade rubber body is first immersed in a chlorine-containing chlorine-treated aqueous solution. Examples of chlorine-treated aqueous solutions include aqueous solutions of hypochlorous acid or hypochlorites (such as calcium hypochlorite or sodium hypochlorite) to which an acid such as hydrochloric acid is added to lower the pH and generate chlorine.

[0031] The chlorine concentration in the chlorinated aqueous solution is preferably 100 ppm to 800 ppm, more preferably 150 ppm to 700 ppm. The pH of the chlorinated aqueous solution is preferably 1.5 to 2.4, more preferably 1.8 to 2.3.

[0032] Next, the blade rubber body, which has been removed from the chlorinated aqueous solution, is immersed in washing water to effectively stop the chlorination reaction.

[0033] Next, the blade rubber body, which has been removed from the washing water, is immersed in warm water for cleaning.

[0034] Then, the wiper blade rubber 10 is obtained by drying the blade rubber body that has been removed from the hot water.

[0035] In the above embodiment, the entire surface of the wiper blade rubber 10 is subjected to chlorination treatment, but the invention is not limited to this configuration, and it is sufficient if the treatment is applied to at least the surface of the lip portion 11 that constitutes the contact sliding portion with other members.

[0036] Furthermore, in order to obtain a wiper blade rubber 10 with excellent wiping properties, at least the lip portion 11 is provided with a graphite coating layer.

[0037] 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, for example, an acrylic resin. The acrylic resin preferably has amino groups in its side chains. Furthermore, the amino groups are preferably primary amino groups.

[0038] As solid lubricants, graphite, molybdenum disulfide, tungsten disulfide, boron nitride, polytetrafluoroethylene (PTFE), etc., can be used, with graphite being preferred.

[0039] -Bending Measurement- For a wiper blade rubber 10, a test piece with a length of 100 mm is cut out. As shown in FIG. 1, the mounting holding portion 12 of this test piece is attached to an elongated fixing jig 20, and the fixing jig 20 with the test piece attached thereto is pressed against a glass disk 21. Water W was sprayed onto the glass disk 21 to wet it, the glass disk 21 was rotated such that the speed of the tip of the test piece reached 1.27 m / s, and the test piece was caused to slide on the glass disk 21.

[0040] In this state, when a load of 40 g / cm is applied, when viewed from the longitudinal direction of the wiper blade rubber, an angle α1 between the horizontal line La of the glass surface and the parallel line Lb of the linear portion of the tip sliding portion 11a, and an angle α2 between the horizontal line La of the glass surface and the parallel line Lc of the linear portion at an intermediate position closer to the shoulder portion 11b than the tip sliding portion 11a in the lip portion 11 are photographed with a digital camera, the photograph data is read by software with a plane measurement function, and the value of α2-α1 is calculated.

[0041] In the present embodiment, α2-α1 is desirably not less than 7 deg and not more than 30 deg.

[0042] -Neck Stiffness Measurement- As shown in FIG. 3, a surface property measuring instrument 1 manufactured by Shinto Scientific Co., Ltd. having a horizontally movable stage 2 and a load cell 5 is used.

[0043] As shown enlarged in FIG. 2, a mounting jig 3 fixed on the stage 2 holds the mounting holding portion 12 of the wiper blade rubber 10 cut to a predetermined length. The length of the wiper blade rubber 10 at the time of measurement is not limited to 3 cm, and may be a length adapted to the measuring instrument.

[0044] Next, by moving the stage 2 horizontally, the mounting jig 3 is moved at a speed of 10 mm / min relative to the load cell 5 not located on the stage 2.

[0045] Next, a tip range accounting for 10% of the lip length from the tip sliding portion 11a to the shoulder portion 11b is brought into contact with a height-adjustable contact portion 4 connected to the load cell 5.

[0046] Then, the load immediately before the neck portion 13 bends and the shoulder portion 11b contacts the mounting holding portion 12 is defined as the neck stiffness.

[0047] In the present embodiment, the neck rigidity per unit length is preferably 43 mN / cm or more and 67 mN / cm or less.

[0048] -Repeated Tensile Test- Using a tensile tester (not shown), the back rubber of the wiper blade rubber 10 is cut out, the convex portions remaining on the cut side are removed by polishing to prepare a test piece with a length of 100 mm. A tensile force is applied to the test piece to stretch it by 100%, and then the operation of returning it to 0% is repeated three times.

[0049] Then, in the third cycle, the 30% modulus, which represents the restoring force of the test piece when the elongation is 30%, is measured.

[0050] In the wiper blade rubber 10 of the present embodiment, the 30% modulus is preferably 0.6 MPa or more and 1.2 MPa or less.

[0051] -Reversal Performance Measurement- Although not shown in detail, in an actual vehicle, the arm pressure applied to the wiper arm fitted with the wiper blade rubber 10 is set to 15 gf / cm, and evaluation is performed by driving the wiper with a water spray rate of 800 ml / min or higher.

[0052] If the water trailing length on the glass surface is 50 mm or less, the result is rated ○; if it exceeds 50 mm, the result is rated ×.

[0053] -Abnormal Noise Measurement- Similarly, in an actual vehicle, the arm pressure applied to the wiper arm fitted with the wiper blade rubber 10 is set to 15 gf / cm, and evaluation is performed by driving the wiper with a water spray rate of 800 ml / min or higher.

[0054] If no abnormal noise occurs, the result is rated ○; if abnormal noise occurs, the result is rated ×. Then, comprehensive evaluation of reversal performance and abnormal noise is performed, and examples more preferable than those rated ○ are rated ◎.

[0055] -Chlorine Film Thickness Measurement- A test piece of the wiper blade rubber 10 is observed with a scanning electron microscope (SEM) to view the tip sliding portion 11a of the lip part 11, and the thickness of the chlorine film formed on the tip sliding portion 11a is measured.

[0056] -Lip Thickness Measurement- The lip thickness at the tip sliding portion 11a of the wiper blade rubber 10 was measured using an image dimension measuring device.

[0057] Figure 4 shows the results of the measurements described above for Examples 1 to 7 and Comparative Examples 1 to 6.

[0058] <Example 1> The lip thickness was 0.60 mm, the neck radius was 0.2 mm, the chlorine film thickness was 1.8 μm, the M30 was 1.00 MPa, the neck rigidity was 45 mN / cm, and the flex was 12.1 deg. The reversal properties were good, no abnormal noise was generated, and the results were more favorable.

[0059] <Example 2> The lip thickness was 0.58 mm, the neck radius was 0.2 mm, the chlorine film thickness was 1.6 μm, the M30 was 1.10 MPa, the neck rigidity was 53 mN / cm, and the flex was 14.7 deg. The reversal properties were good, no abnormal noise was generated, and the results were more favorable.

[0060] <Example 3> The lip thickness was 0.59 mm, the neck radius was 0.2 mm, the chlorine film thickness was 1.1 μm, the M30 was 1.14 MPa, the neck rigidity was 63 mN / cm, and the flex was 22.4 deg. The reversal properties were good, no abnormal noise was generated, and the results were more favorable.

[0061] <Example 4> The lip thickness was 0.61 mm, the neck radius was 0.2 mm, the chlorine film thickness was 2.0 μm, the M30 was 0.90 MPa, the neck rigidity was 47 mN / cm, and the flex was 7.0 deg. It also had good reversal properties and no abnormal noise was generated.

[0062] <Example 5> The lip thickness was 0.60 mm, the neck radius was 0.2 mm, the chlorine film thickness was 2.0 μm, the M30 was 1.20 MPa, the neck rigidity was 67 mN / cm, and the flex was 7.0 deg. It also had good reversal properties and no abnormal noise was generated.

[0063] <Example 6> The lip thickness was 0.58 mm, the neck radius was 0.2 mm, the chlorine film thickness was 1.1 μm, the M30 was 0.60 MPa, the neck rigidity was 43 mN / cm, and the flex was 30.0 deg. It also had good reversal properties and no abnormal noise was generated.

[0064] <Example 7> The lip thickness was 0.58 mm, the neck radius was 0.3 mm, the chlorine film thickness was 1.0 μm, the M30 was 1.14 MPa, the neck rigidity was 67 mN / cm, and the flex was 30.0 deg. It also had good reversal properties and no abnormal noise was generated.

[0065] <Comparative Example 1> The lip thickness was 0.65 mm, the neck radius was 0.2 mm, the chlorine film thickness was 2.0 μm, the M30 was 0.50 MPa, the neck rigidity was 38 mN / cm, and the flex was 7.0 deg. It had poor reversal properties and produced abnormal noise.

[0066] <Comparative Example 2> The lip thickness was 0.58 mm, the neck radius was 0.2 mm, the chlorine film thickness was 0.9 μm, the M30 was 0.55 MPa, the neck rigidity was 35 mN / cm, and the flex was 4.3 deg. It had poor reversal properties and produced abnormal noise.

[0067] <Comparative Example 3> The lip thickness was 0.56 mm, the neck radius was 0.3 mm, the chlorine film thickness was 1.0 μm, the M30 pressure was 1.30 MPa, the neck rigidity was 77 mN / cm, and the flex was 5.7 deg. No abnormal noise was generated, but the inversion performance was poor and the water spurt exceeded 50 mm.

[0068] <Comparative Example 4> The lip thickness was 0.60 mm, the neck radius was 0.2 mm, the chlorine film thickness was 2.3 μm, the M30 was 1.20 MPa, the neck rigidity was 70 mN / cm, and the flex was 5.0 deg. Although the inversion ability was relatively good, an abnormal noise was generated.

[0069] <Comparative Example 5> The lip thickness was 0.56 mm, the neck radius was 0.2 mm, the chlorine film thickness was 0.3 μm, the M30 was 1.15 MPa, the neck rigidity was 63 mN / cm, and the flex was 37.0 deg. No abnormal noise was generated, but the inversion performance was poor and the water pull exceeded 50 mm.

[0070] <Comparative Example 6> The lip thickness was 0.57 mm, the neck radius was 0.2 mm, the chlorine film thickness was 0.4 μm, the M30 was 0.53 MPa, the neck rigidity was 33 mN / cm, and the flex was 35.0 deg. No abnormal noise was generated, but the inversion performance was poor and the water pull exceeded 50 mm.

[0071] As can be seen from the comparison between the example and the comparative example above, if the neck rigidity is made less than 43 mN / cm, the neck portion 13 becomes too soft, worsening its inversion properties and generating abnormal noise. Conversely, if it is made greater than 67 mN / cm, the neck portion 13 becomes too hard, worsening its inversion properties and generating abnormal noise. However, by setting it between 43 mN / cm and 67 mN / cm, the generation of abnormal noise is suppressed without changing the neck rigidity in the longitudinal direction of the lip portion 11. Furthermore, if α2-α1 becomes less than 7 deg, the inversion properties worsen and abnormal noise is generated. While it is difficult to make it greater than 30 deg due to the constraints of the shape of the lip portion 11, setting it between 7 deg and 30 deg allows for the suppression of abnormal noise with an appropriate shape for the lip portion 11.

[0072] Furthermore, if the thickness of the chlorine film is made thinner than 1.0 μm, the neck rigidity decreases, and if it is made thicker than 2.0 μm, the neck rigidity becomes too high or the lip portion 11 becomes too stiff. However, by setting the thickness to between 1.0 μm and 2.0 μm, an appropriate balance of neck rigidity and flexibility of the lip portion 11 can be obtained.

[0073] Furthermore, if the 30% modulus is less than 0.6 MPa, the reversal properties deteriorate, and if it is greater than 1.2 MPa, the reversal properties deteriorate. However, by setting it between 0.6 MPa and 1.2 MPa, the reversal properties improve and water stagnation is less likely to occur.

[0074] Therefore, according to the wiper blade rubber 10 of this embodiment, the reversal ability can be improved by increasing the neck rigidity, and the generation of abnormal noise during reversal can be suppressed by allowing the lip portion 11 to flex appropriately.

[0075] The embodiments described above are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or uses.

[0076] 10 Wiper blade rubber 11 Lip part 11a Tip sliding part 11b Shoulder part 12 Mounting and holding part 13 Neck part 20 Fixing jig 21 Glass disc

Claims

1. A wiper blade rubber having a triangular cross-section lip portion having a tip sliding portion that contacts and slides on a glass surface and a shoulder portion that gradually widens from the tip sliding portion, a mounting holding portion that is held by a wiper holding portion, and a thin-walled neck portion that connects the shoulder portion and the mounting holding portion, wherein in a surface quality measuring machine, the mounting holding portion of the wiper blade rubber cut to a predetermined length is held in a mounting jig, the mounting jig is moved at a speed of 10 mm / min relative to a load cell, the tip range of 10% of the lip length from the tip sliding portion to the shoulder portion is brought into contact with the load cell, and the neck stiffness, which is the load just before the shoulder portion contacts the mounting holding portion, is 43 mN / cm or more and 67 mN / cm or less, and when the tip sliding portion is brought into contact with the glass surface of glass on a rotating disc testing machine with the mounting holding portion held, and a load of 40 g / cm is applied, the wiper blade rubber, when viewed from the longitudinal direction, A wiper blade rubber characterized in that the angle α1 between the horizontal line of the glass surface and the parallel line of the straight portion of the tip sliding part, and the angle α2 between the horizontal line of the glass surface and the parallel line of the straight portion at an intermediate position on the shoulder side of the lip part compared to the tip sliding part, are such that α2 - α1 is 7 degrees or more and 30 degrees or less.

2. The wiper blade rubber according to claim 1, characterized in that the polymer is natural rubber or a blend of natural rubber and chloroprene rubber, and the rubber composition comprises carbon black.

3. The wiper blade rubber according to claim 2, characterized in that at least the lip portion is provided with a graphite coating layer.

4. The wiper blade rubber according to claim 3, characterized in that at least the lip portion has a chlorine-treated chlorine film of 1.0 μm or more and 2.0 μm or less formed beneath the coating layer.

5. A wiper blade rubber according to any one of claims 1 to 4, characterized in that, after applying a tensile force and stretching it to 100%, the operation of returning it to 0% is repeated three times, and on the third time, the 30% modulus is 0.6 MPa or more and 1.2 MPa or less.

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