JP2013124337A - Wiper blade rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiper blade rubber having excellent low frictional properties and exhibiting excellent wiping/cleaning performance.SOLUTION: The wiper blade rubber includes a composite of a fluororesin and a dynamically crosslinked fluororubber. Preferably, the fluororesin is a non-perfluororesin, and the fluororubber is a vinylidene fluoride/hexafluoropropylene copolymer or a vinylidene fluoride/hexafluoropropylene/tetrafluoroethylene copolymer.

Description

The present invention relates to a blade rubber of a wiper used for a vehicle or the like.

The wiper wipes rain and dirt so that the visibility of the front window, rear window, etc. can be secured due to rain, mud, etc. Used for blades.

For wiper blade rubber, natural rubber, synthetic rubber, etc. were used because of their flexibility and wiping performance. However, conventional wiper blade rubber has a problem that the sliding resistance between glass and rubber is large during wiping. Attempts have been made to reduce the friction on the rubber surface.

For example, Patent Document 1 includes a self-lubricating rubber in which 5 to 60 parts by weight of a tetrafluoroethylene polymer and 0.1 to 10 parts by weight of an electrophilic reagent are present in 100 parts by weight of a vulcanized rubber. A wiper blade rubber characterized by is described.
Patent Document 2 discloses that at least a sliding surface is formed from a lubricating rubber composition, and the lubricating rubber composition includes a thermoplastic fluororesin that is a first essential component, a fluororubber that is a second essential component, And a wiper blade rubber comprising a low molecular weight fluorine-containing polymer which is a third essential component.

Japanese Patent Laid-Open No. 9-40810 Japanese Patent Laid-Open No. 5-209101

An object of the present invention is to provide a wiper blade rubber having excellent low friction properties and exhibiting excellent wiping properties.

The inventors of the present invention have made extensive studies on a wiper blade rubber having excellent low-friction properties during wiping and excellent wiping performance. As a result, a wiper blade rubber comprising a composite of a fluororesin and a dynamically crosslinked fluororubber Has found that it has an excellent low friction property against the surface to be wiped and can exhibit an excellent wiping property, and the present invention has been completed.

That is, the present invention is a wiper blade rubber comprising a composite of a fluororesin and a dynamically crosslinked fluororubber.

The fluororesin is a non-perfluoro resin, and the fluororubber is preferably a vinylidene fluoride / hexafluoropropylene copolymer or a vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene copolymer.

The fluororesin is preferably an ethylene / tetrafluoroethylene copolymer.

The composite of the fluororesin and the dynamically crosslinked fluororubber is preferably 5 to 500 parts by mass of the dynamically crosslinked fluororubber with respect to 100 parts by mass of the fluororesin.

Since the wiper blade rubber of the present invention has the above-described configuration, it has excellent low friction properties and can exhibit excellent wiping properties.

It is a cross-sectional schematic diagram which shows an example of the wiper blade rubber | gum of this invention.

The wiper blade rubber of the present invention is a composite of a fluororesin and a dynamically crosslinked fluororubber. Since the wiper blade rubber of the present invention has the above-described configuration, it has excellent low friction properties derived from fluororesin and also has flexibility derived from fluororubber, so that it exhibits excellent wiping performance. it can.
Moreover, since it has excellent abrasion resistance due to the characteristics of the fluororesin used, it is possible to suppress defects and the like caused by hard powder contained in sand, dust, mud and the like. Since defects and the like can be suppressed, excellent wiping performance can be maintained in the long term.
Further, since the composite of the fluororesin and the dynamically cross-linked fluororubber is formed by integrally forming the dynamically cross-linked fluororubber and the fluororesin, the wiper blade rubber of the present invention is durable. Also excellent in properties.
In addition, due to the characteristics of the fluororesin used, it exhibits excellent non-adhesiveness and suppresses sticking to the glass surface even when it has been in contact with the glass surface being wiped for a long time Can do.
Each element will be described below.

The wiper blade rubber of the present invention comprises a composite of a fluororesin and a dynamically crosslinked fluororubber.

The fluororesin is a polymer composed of polymerized units based on a fluorine-containing ethylenic monomer. The wiper blade rubber of the present invention has excellent heat resistance and chemical resistance because the fluororesin is a polymer having a polymer unit composed of a fluorine-containing ethylenic monomer. The fluororesin usually has a clear melting point.
As the fluororesin, one type of polymer having a fluorine-containing ethylenic monomer unit may be used, or two or more types may be used in combination.
The fluororesin is preferably a non-perfluororesin because dispersibility of the crosslinked rubber particles in the fluororesin is improved.

Examples of the fluorine-containing ethylenic monomer include tetrafluoroethylene (TFE) and formula (1):
CF ₂ = CF-Rf ¹ (1)
(Where Rf ¹ is —CF ₃ or —ORf ² ; Rf ² is a perfluoroalkyl group having 1 to 5 carbon atoms); chlorotrifluoroethylene (CTFE), trifluoro Ethylene, hexafluoroisobutene, vinylidene fluoride (VdF), vinyl fluoride, formula (2):
^{_{CH 2 = CX 2 (CF 2}} ) n X 3 (2)
(Wherein, X ² is a hydrogen atom or a fluorine atom; X ³ is a hydrogen atom, a fluorine atom or a chlorine atom; n is an integer of 1 to 10).

The fluororesin is preferably a polymer having a polymer unit based on a fluorine-containing ethylenic monomer and a polymer unit based on a non-fluorine-containing ethylenic monomer. The selection of the non-fluorinated ethylenic monomer may be performed in consideration of the characteristics and functions that can be imparted by the non-fluorinated ethylenic monomer.

Specific examples of the non-fluorinated ethylenic monomer include olefins such as ethylene and propylene; alkyl vinyl ethers and the like. Here, the alkyl vinyl ether refers to an alkyl vinyl ether having an alkyl group having 1 to 5 carbon atoms.

As the fluororesin, a wiper blade rubber having superior wiping properties can be obtained, the heat resistance, chemical resistance and oil resistance of the wiper blade rubber are excellent, and further, the molding process is facilitated. The copolymers I) to (V) are particularly preferred.

(I) Ethylene / TFE copolymer (hereinafter also referred to as “ETFE”)
ETFE is a copolymer composed of polymerized units based on TFE (TFE units) and polymerized units based on ethylene (ethylene units). ETFE is preferable in that a wiper blade rubber having better wiping properties can be obtained, mechanical properties are excellent, and fluorine rubber can be easily cross-linked.
ETFE has a molar ratio of TFE / ethylene of preferably (20 to 90) / (80 to 10), more preferably (37 to 85) / (63 to 15), and (38 to 80). ) / (62 to 20).

ETFE may further comprise polymerized units based on monomers copolymerizable with TFE and ethylene. As for ETFE, it is preferable that the polymerized unit based on the monomer copolymerizable with TFE and ethylene is 0.1 to 10 mol%, preferably 0.1 to 5 mol%, based on all polymerized units. More preferably, it is more preferable that it is 0.2-4 mol%.

As a monomer copolymerizable with TFE and ethylene, formulas (3) to (6):
CH ₂ = CX ⁴ Rf ³ (3)
CF ₂ = CFRf ³ (4)
CF ₂ = CFORf ³ (5)
CH ₂ = C (Rf ³ ) ₂ (6)
(Wherein, X ⁴ is a hydrogen atom or a fluorine atom; Rf ³ is a fluoroalkyl group optionally containing an etheric oxygen atom). Rf ³ is preferably a fluoroalkyl group having 1 to 8 carbon atoms.

Specific examples of the fluorine-containing vinyl monomer represented by the formulas (3) to (6) include 1,1-dihydroperfluoropropene-1, 1,1-dihydroperfluorobutene-1, 1,1,5-trimethyl Hydroperfluoropentene-1,1,1,7-trihydroperfluoroheptene-1,1,1,2-trihydroperfluorohexene-1,1,1,2-trihydroperfluorooctene-1, 2,2,3,3,4,4,5,5-octafluoropentyl vinyl ether, perfluoro (methyl vinyl ether), perfluoro (propyl vinyl ether), hexafluoropropene, perfluorobutene-1, 3,3,3 - trifluoro-2- (trifluoromethyl) propene -1,2,3,3,4,4,5,5- heptafluoro-1-pentene (CH ₂ = CFCF ₂ CF ₂ CF ₂ H).

Among them, ETFE is a polymer unit based on TFE, a polymer unit based on ethylene, and a formula (3) because stress crack resistance is excellent.
CH ₂ = CX ⁴ Rf ³ (3)
(Wherein X ⁴ is a hydrogen atom or a fluorine atom; Rf ³ is a fluoroalkyl group optionally containing an etheric oxygen atom), and a copolymer comprising polymerized units based on a fluorine-containing ethylenic monomer It is preferable that

ETFE is also a polymerized unit based on TFE, a polymerized unit based on ethylene, and a formula (1):
CF ₂ = CF-Rf ¹ (1)
(Wherein Rf ¹ is —CF ₃ or —ORf ² ; Rf ² is a perfluoroalkyl group having 1 to 5 carbon atoms), and a copolymer comprising polymerized units based on a perfluoroethylenically unsaturated compound. It is also preferable.
The ETFE is at least one copolymer selected from the group consisting of ethylene / TFE / HFP copolymer and ethylene / TFE / perfluoro (alkyl vinyl ether) (PAVE) copolymer. More preferred.

(II) Polyvinylidene fluoride (PVdF)

(III) Ethylene / CTFE copolymer (hereinafter also referred to as ECTFE)
The ethylene / CTFE copolymer is a copolymer composed of polymerized units based on CTFE and polymerized units based on ethylene.

(IV) A polymer unit based on a copolymer TFE composed of a polymer unit based on TFE and a polymer unit based on a perfluoroethylenically unsaturated compound represented by the above formula (1), and a formula shown in the above formula (1) The copolymer comprising polymerized units based on the perfluoroethylenically unsaturated compound is at least one selected from the group consisting of TFE / PAVE copolymer (PFA) and TFE / HFP copolymer (FEP). A copolymer is preferred.
By using PFA or FEP as the fluororesin, the wiper blade rubber of the present invention is more excellent in heat resistance. In addition, chemical resistance is excellent.
A copolymer comprising polymerized units based on TFE and polymerized units based on the perfluoroethylenically unsaturated compound represented by the above formula (1) is TFE / (perfluoroethylenically unsaturated compound represented by the formula (1)) ) Is a molar ratio of (70 to 99) / (1 to 30), more preferably (80 to 97) / (3 to 20).
When there are too few TFE units, there exists a tendency for a mechanical physical property to fall, and when too much, melting | fusing point becomes high too much and there exists a tendency for a moldability to fall.
A copolymer comprising a TFE unit and a polymerized unit based on the perfluoroethylenically unsaturated compound represented by the above formula (1) can be copolymerized with TFE and the perfluoroethylenically unsaturated compound represented by the formula (1). It may be composed of polymerized units based on various monomers.

(V) CTFE / TFE Copolymer CTFE / TFE copolymer is composed of polymerized units based on CTFE (CTFE units) and polymerized units based on TFE (TFE units).
The CTFE-TFE copolymer has a CTFE / TFE molar ratio of preferably (2-98) / (98-2), more preferably (5-90) / (95-10). . If the CTFE unit is too small, melt processing tends to be difficult, and if it is too large, the heat resistance and chemical resistance during molding may be deteriorated.
The CTFE-TFE copolymer is also preferably a copolymer comprising polymerized units based on the perfluoroethylenically unsaturated compound represented by the above formula (1). The CTFE-TFE copolymer has 0.1 to 10 mol% of polymerized units based on the perfluoroethylenically unsaturated compound represented by the formula (1) with respect to all polymerized units, and includes CTFE units and TFE units. Is preferably 90 to 99.9 mol%. If the perfluoroethylenically unsaturated compound unit is less than 0.1 mol%, the moldability, environmental stress crack resistance and stress crack resistance tend to be inferior, and if it exceeds 10 mol%, heat resistance, mechanical properties, and productivity are exceeded. Tend to be inferior.

Among the above copolymers (I) to (V), since the crosslinking is easy, the fluororesin is preferably at least one non-perfluoro copolymer selected from the group consisting of ETFE, PVdF and ECTFE. ETFE is more preferable because of its good heat resistance, mechanical properties, and abrasion resistance.

The number average molecular weight of the fluororesin is preferably from 1,000 to 1,000,000, more preferably from 5,000 to 500,000 in terms of good mechanical properties and molding processability.

The melting point of the fluororesin is preferably 120 to 330 ° C. More preferably, it is 180-280 degreeC. The melting point of the fluororesin is a value determined by differential scanning calorimetry (DSC). Specifically, the temperature showing the endothermic peak top obtained when the temperature is raised at 10 ° C./min by differential scanning calorimetry (DSC) is defined as the melting point.

The dynamically crosslinked fluororubber is obtained by dynamically crosslinking (uncrosslinked) fluororubber. Fluoro rubber can give appropriate elasticity and flexibility (flexibility) to a composite of fluororesin and dynamically cross-linked fluoro rubber. It is not limited. Fluoro rubber is usually one that does not have a clear melting point.

Examples of the fluororubber include tetrafluoroethylene, vinylidene fluoride, and formula (1) because particles having properties as a rubber elastic body are obtained.
CF ₂ = CF-Rf ¹ (1)
Wherein Rf ¹ is —CF ₃ or —ORf ² (Rf ² is a perfluoroalkyl group having 1 to 5 carbon atoms), and is selected from the group consisting of perfluoroethylenically unsaturated compounds. A polymer comprising polymerized units based on these monomers is preferred.

Examples of the fluoro rubber include non-perfluoro fluoro rubber and perfluoro fluoro rubber, but non-perfluoro fluoro rubber is preferable.

Non-perfluorofluororubbers include vinylidene fluoride (VdF) fluororubber, tetrafluoroethylene (TFE) / propylene fluororubber, tetrafluoroethylene (TFE) / propylene / vinylidene fluoride (VdF) fluororubber, ethylene / Hexafluoropropylene (HFP) fluorine rubber, Ethylene / Hexafluoropropylene (HFP) / Vinylidene fluoride (VdF) fluorine rubber, Ethylene / Hexafluoropropylene (HFP) / Tetrafluoroethylene (TFE) fluorine rubber, Fluoro Examples thereof include silicone-based fluororubber and fluorophosphazene-based fluororubber, and these may be used alone or in any combination. Among these, as the fluororubber, VdF fluororubber or TFE / propylene fluororubber is more preferable, and VdF fluororubber is more preferable.

The VdF-based fluororubber is a polymer composed of polymerized units based on VdF and polymerized units based on monomers other than VdF. The VdF-based fluororubber preferably has 20 to 90 mol% of polymerized units based on VdF with respect to all polymerized units. The lower limit of the polymerized units based on VdF is more preferably 40 mol%, further preferably 45 mol%, and particularly preferably 50 mol%. The upper limit of the polymerized units based on VdF is more preferably 85 mol%, and still more preferably 80 mol%.

In the VdF-based fluororubber, examples of monomers other than VdF include, for example, TFE, HFP, PAVE, CTFE, trifluoroethylene, trifluoropropylene, tetrafluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, Fluorine-containing monomers such as vinyl fluoride and iodine-containing fluorinated vinyl ethers; and fluorine-free monomers such as ethylene (Et), propylene (Pr), and alkyl vinyl ethers. Among these fluorine-containing monomers and non-fluorine-containing monomers, one type may be used, or two or more types may be used.
As the PAVE, perfluoro (methyl vinyl ether) or perfluoro (propyl vinyl ether) is preferable, and perfluoro (methyl vinyl ether) is particularly preferable.

Examples of the VdF-based fluororubber include VdF / HFP copolymer, VdF / HFP / TFE copolymer, VdF / CTFE copolymer, VdF / CTFE / TFE copolymer, VdF / PAVE copolymer, VdF / TFE copolymer. / PAVE copolymer, VdF / HFP / PAVE copolymer, VdF / HFP / TFE / PAVE copolymer, VdF / TFE / Pr copolymer, and VdF / Et / HFP copolymer Preferred is at least one copolymer.
In the VdF-based fluororubber, the monomer other than VdF is more preferably at least one monomer selected from the group consisting of TFE, HFP, and PAVE, and in particular, VdF / HFP From polymers, VdF / HFP / TFE copolymers, VdF / PAVE copolymers, VdF / TFE / PAVE copolymers, VdF / HFP / PAVE copolymers, and VdF / HFP / TFE / PAVE copolymers At least one copolymer selected from the group consisting of These copolymers preferably satisfy the content range of polymerized units based on VdF in the VdF fluororubber.

The VdF / HFP copolymer has a molar ratio of VdF / HFP of preferably (45 to 85) / (55 to 15), more preferably (50 to 80) / (50 to 20). More preferably (60-80) / (40-20).

The VdF / HFP / TFE copolymer preferably has a molar ratio of VdF / HFP / TFE of (30-80) / (10-35) / (4-35).

The VdF / PAVE copolymer preferably has a molar ratio of VdF / PAVE of (65 to 90) / (35 to 10).

The VdF / TFE / PAVE copolymer preferably has a molar ratio of VdF / TFE / PAVE of (40-80) / (3-40) / (15-35).

In the VdF / HFP / TFE / PAVE copolymerization, the molar ratio of VdF / HFP / TFE / PAVE is (40 to 90) / (0 to 25) / (0 to 40) / (3 to 35). Preferably, it is (40-80) / (3-25) / (3-40) / (3-25).

The TFE / propylene-based fluororubber is a copolymer of (45 to 70) / (55 to 30) with a molar ratio of TFE / propylene. In addition to the polymerized units based on TFE and propylene, 0 to 40 mol% of polymerized units based on monomers copolymerizable with TFE and propylene may be further contained based on the total polymerized units. As a monomer copolymerizable with TFE and propylene, for example, PAVE is preferable.

Examples of the perfluoro fluorine rubber include those made of TFE / PAVE. It is preferable that TFE / PAVE is (50-90) / (50-10) by molar ratio, More preferably, it is (50-80) / (50-20), More preferably, (55-55 75) / (45-25).
Examples of PAVE in this case include perfluoro (methyl vinyl ether) and perfluoro (propyl vinyl ether), and these can be used alone or in any combination.

The number average molecular weight of the fluororubber is preferably 1000 to 1200000, and more preferably 5000 to 900000. If the molecular weight is less than 1000, crosslinking does not proceed efficiently, and the mechanical properties of the composite with the resulting fluororesin tend to be inferior, and if the molecular weight exceeds 1200000, it is inferior in economics due to the problem of fluororubber productivity. .

The fluororubber can be produced by a conventional method such as emulsion polymerization, suspension polymerization, or solution polymerization. In particular, according to a polymerization method using an iodine compound (or bromine compound) known as iodine (or bromine) transfer polymerization, a fluororubber having a narrow molecular weight distribution can be produced.

In the dynamic crosslinking method, it is preferable to use particulate fluororubber (fluororubber particles) from the viewpoint of improving the composite dispersibility with the fluororesin and the supply stability to the mixer.
For example, when a fluororubber is produced by emulsion polymerization or suspension polymerization, a particulate fluororubber is obtained. When the produced fluororubber is in a particulate form, it may be used as it is, or the produced particulate fluororubber You may use the fluororubber particle obtained by further grind | pulverizing. When fluororubber is obtained by solution polymerization, fluororubber particles obtained by pulverizing a lump obtained by solution polymerization can be used.

The cross-linking of the fluororubber is performed by a so-called dynamic cross-linking method in which the fluororesin and the fluororubber are kneaded and cross-linked simultaneously. That is, the dynamically crosslinked fluororubber is preferably obtained by crosslinking a composition comprising a fluororesin and fluororubber by a dynamic crosslinking method.

The dynamic cross-linking method may use a mixer capable of simultaneous melting and blending, such as a rotary stirring device such as a Banbury mixer or a kneader, or a twin screw extruder. Among these, a twin-screw extruder is preferable because a pellet-like composite can be easily obtained and the productivity is high.

The average particle size of the fluororubber particles is not particularly limited, but may be appropriately selected depending on the application and required characteristics.
When supplying fluororesin and fluororubber particles to a batch type mixer such as a Banbury mixer or kneader, the average particle size of the fluororubber particles is 0.01 to from the viewpoint of improving composite dispersibility with fluororesin and improving physical properties. It is preferable that it is 100 micrometers. More preferably, it is 30 micrometers or less, More preferably, it is 10 micrometers or less.
When supplying to continuous mixers, such as a twin-screw extruder, it is preferable to use what was pelletized to 1-5 mm in diameter and 1-5 mm in length with granulators, such as a sheet cutter and a feeder ruder. More preferably, it is in the form of a pellet having a diameter of 2 to 4 mm and a length of 2 to 4 mm.

When the fluororubber contains a crosslinkable group (iodine atom, bromine atom, amino group, cyano group, carboxyl group, alkoxycarbonyl group, hydroxyl group, etc.), depending on the type of the crosslinkable group It can be selected appropriately.
Examples of the crosslinking system include a polyamine crosslinking system, a polyol crosslinking system, a peroxide crosslinking system, an imidazole crosslinking system, a triazine crosslinking system, an oxazole crosslinking system, and a thiazole crosslinking system. Among these, the heat resistance and economy of the crosslinked structure are included. From this point of view, a polyamine crosslinking system, a polyol crosslinking system, or a peroxide crosslinking system is preferred.

The cross-linking agent may be appropriately selected according to the above-mentioned cross-linking system, and polyol-based cross-linking agent, peroxide-based cross-linking agent, polyamine-based cross-linking agent, imidazole-based cross-linking agent, triazine-based cross-linking agent, oxazole-based cross-linking agent, thiazole-based. A crosslinking agent or the like is used. These crosslinking agents may be used alone or in combination. In order to advance the crosslinking reaction efficiently, a crosslinking accelerator or an acid acceptor may be added.

For the preparation of the composite of the fluororesin and the dynamically crosslinked fluororubber constituting the wiper blade rubber of the present invention, a method of crosslinking while kneading the fluororesin and the fluororubber (dynamic crosslinking method) is adopted. Is done.

As the dynamic cross-linking method, for example, a method of dynamically cross-linking fluoro rubber under the melting condition of the fluoro resin in the presence of fluoro resin, fluoro rubber and a cross-linking agent is preferable.

Here, dynamically crosslinking means that the fluororubber is dynamically crosslinked simultaneously with melt kneading using a mixer such as a Banbury mixer, a pressure kneader, or an extruder.
The mixer is preferably an extruder such as a twin screw extruder in that a high shear force can be applied.

The melting condition means that the temperature is equal to or higher than the melting point of the fluororesin. A suitable temperature range varies depending on the melting point of the fluororesin and the glass transition temperature of the fluororubber, but is preferably 120 to 330 ° C, and more preferably 130 to 320 ° C. When the temperature is less than 120 ° C., the progress of the crosslinking reaction is delayed, and the dynamically crosslinked fluororubber particles (crosslinked fluororubber particles) dispersed in the fluororesin tend to be coarsened, exceeding 330 ° C. And fluororubber tends to be thermally deteriorated.

For example, in a composite of a fluororesin and a dynamically cross-linked fluororubber, a fluororesin, a fluororubber and a cross-linking agent are added to a mixer, and then the fluororesin, the fluororubber and the cross-linking agent What is obtained by cross-linking fluororubber while kneading at a temperature is preferable. Alternatively, the vulcanizing agent can be kneaded in advance in the fluororubber.

A composite of a fluororesin and a dynamically cross-linked fluororubber has a structure in which the fluororesin forms a continuous phase and cross-linked fluororubber particles form a dispersed phase, or a fluororubber dynamically cross-linked with a fluororesin And have a structure forming a co-continuous phase.
Among these, it is more preferable that the fluororesin has a structure in which a continuous phase is formed and the crosslinked fluororubber particles form a dispersed phase. A composite of a fluororesin having a structure in which a fluororesin forms a continuous phase and a cross-linked fluororubber particle forms a dispersed phase and a dynamically cross-linked fluororubber has excellent heat resistance, chemical resistance, and oil resistance. In addition, it has good flexibility (softness) and further good moldability. At that time, the cross-linked fluororubber particles forming the dispersed phase preferably have an average particle size of 0.01 to 30 μm, more preferably 0.1 to 10 μm, from the viewpoint of good mechanical properties.

Even when fluororubber forms a continuous phase at the beginning of dynamic cross-linking, the melt viscosity increases due to cross-linking of the fluororubber with the progress of the cross-linking reaction. Sometimes it becomes. Moreover, a co-continuous phase with a fluororesin may be formed.
A part of the structure in which the fluororesin forms a continuous phase and the cross-linked fluororubber particles form a dispersed phase may include a co-continuous structure of the fluororesin and the dynamically cross-linked fluororubber.

In the present invention, the average particle size of the cross-linked fluororubber particles in the composite of the fluororesin and the dynamically cross-linked fluororubber is confirmed by using any one of AFM, SEM, TEM, or a combination thereof. be able to. For example, when using AFM, the difference obtained from the surface information of the continuous phase fluororesin and the dispersed cross-linked fluororubber particles is obtained as a light / dark image, and binarization is possible by dividing the light / dark into gradations. Become. The binarization position is set to the center level divided by gradation, whereby an image with a clear contrast is obtained, and the particle diameter of the cross-linked fluororubber in the dispersed phase can be read. When SEM is used, the AFM is enhanced by enhancing the contrast or adjusting the brightness or darkness so that the cross-linked fluororubber particles in the dispersed phase are clear from the image obtained by the reflected electron image. Similarly, the particle diameter of the cross-linked fluororubber in the dispersed phase can be read. In the case of TEM as well as SEM, the particle diameter of the cross-linked fluororubber in the dispersed phase can be read as in AFM and SEM by adjusting the contrast of the obtained image, or the adjustment of brightness or darkness on the image.

In the composite of fluororesin and dynamically cross-linked fluororubber, the ratio of fluororesin and dynamically cross-linked fluororubber is the type, application, required characteristics, and expression of fluororesin and dynamically cross-linked fluororubber. What is necessary is just to select suitably according to a physical property etc. For example, the composite of fluororesin and the dynamically cross-linked fluororubber is 5 to 500 parts by mass of dynamically cross-linked fluororubber with respect to 100 parts by mass of fluororesin. Preferably there is. More preferably, the fluororubber dynamically crosslinked with respect to 100 parts by mass of the fluororesin is 10 to 400 parts by mass, and still more preferably 20 to 300 parts by mass. When the proportion of the dynamically crosslinked fluororubber is too small, the flexibility tends to be insufficient, and when it is too large, the mechanical strength tends to decrease.

The melt flow rate (MFR) of the composite of the fluororesin and the dynamically crosslinked fluororubber is preferably 0.5 to 30 g / 10 min from the viewpoint of good fluidity and moldability. More preferably, it is ˜25 g / 10 minutes. MFR is measured using a melt flow rate measuring device manufactured by Toyo Seiki Seisakusho Co., Ltd., for example, under conditions of 297 ° C. and a load of 5000 g.

The composite of the fluororesin and the dynamically crosslinked fluororubber may contain a usual additive such as a filler, a processing aid, a plasticizer, a colorant and the like, if necessary. These additives may be blended together with the fluororesin and the fluororubber when preparing a composite of the fluororesin and the dynamically crosslinked fluororubber. Or you may mix | blend beforehand with one of a fluororesin or fluororubber.

Next, a method for forming the wiper blade rubber of the present invention will be described.

Here, a specific method for obtaining the wiper blade rubber of the present invention will be briefly described. However, the method of obtaining the wiper blade rubber of the present invention is not limited to the following method.

Examples of the method for obtaining the wiper blade rubber of the present invention include the following methods.
For example, after preparing a composite of fluororesin and dynamically cross-linked fluororubber by the above dynamic cross-linking method, the composite is molded using a press molding machine, transfer molding machine, injection molding machine, etc. The wiper blade rubber can be obtained.

The shape of the wiper blade rubber of the present invention may be a general shape and may be appropriately determined according to the intended use.

FIG. 1 is a schematic cross-sectional view showing an example of the wiper blade rubber of the present invention. The wiper blade rubber 10 of the present invention has a head part 11 and a wedge part 13, and the head part 11 and the wedge part 13 are coupled via a bridge part 12. The width of the wedge portion 13 decreases toward the wiper edge portion 14 that comes into contact with the glass 15 to be wiped from the head portion 11 side.
When the wiper edge portion 14 in contact with the glass surface is made of a composite of a fluororesin and a dynamically crosslinked fluororubber, the surface of the wiper edge portion 14 is wiped off because of its low frictional property. The friction with the surface of the glass 15 becomes lower.
Further, since the wiper blade rubber 10 as a whole adheres to the surface of the glass 15 to be wiped without losing the inherent flexibility of the rubber, excellent wiping performance is exhibited.

The wiper blade rubber of the present invention can be used for, for example, vehicles such as automobiles, trains, aircraft, ships, and wiper blades for various machine tools. The place where the wiper blade rubber is disposed is not particularly limited, and can be used for a front window, a rear window, various mirrors, and the like.

Next, the present invention will be described with reference to examples, but the present invention is not limited to such examples.

Various characteristics in Examples and Comparative Examples were tested by the following methods.

[Wiper performance test]
The molded wiper blade rubber was attached to a vehicle wiper blade and the wiper performance was tested. The wiper is operated to reciprocate 55 times per minute, and the glass surface is wiped in three states: a dry state, a sprayed state (there is a partially dried state), and a water discharge state (continuously spraying water throughout). The presence or absence of sweepability and stick-slip phenomenon was observed. Furthermore, the presence or absence of the stick-slip phenomenon after the wiper was operated continuously for 100 hours was observed.

Wiping property ○: No wiping residue was observed at the time of wiping Δ: Slight wiping residue was observed ×: Evaluation of stick-slip phenomenon where wiping residue was observed ○: No stick-slip occurred △: Stick Occasional slip x: Stick-slip occurred frequently

[Melt flow rate (MFR)]
Using a melt indexer (manufactured by Toyo Seiki Seisakusho Co., Ltd.), the mass (g) of the polymer flowing out per unit time (10 minutes) from a nozzle with a diameter of 2 mm and a length of 8 mm under a 5 kg load at 297 ° C. did.

[Mooney viscosity]
The Mooney viscosity is a value obtained according to ASTM-D1646.
Measuring equipment: ALPHA2000 TECHNOLOGIES MV2000E rotor speed: 2 rpm
Measurement temperature: 100 ° C

[Melting point of fluororesin]
In differential scanning calorimetry (DSC), the endothermic peak top obtained when the temperature was raised at 10 ° C./min was taken as the melting point.

[Average particle diameter of crosslinked fluororubber particles]
A sample (composite of the obtained fluororesin and dynamically cross-linked fluororubber) was cut with a microtome under freezing to obtain a longitudinal section, and the longitudinal section of the sample was 10 μm square (four sides) by AFM The range of was observed by the phase imaging method. The long diameter and short diameter of the cross-linked fluororubber particles displayed in black were measured, and the average of these was taken as the particle diameter of the cross-linked fluororubber particles. The average particle diameter of 100 arbitrary crosslinked fluororubber particles was defined as the average particle diameter of the crosslinked fluororubber particles.

Example 1
100 parts by mass of ternary VdF rubber (VdF / TFE / HFP = 50/20/30 (molar ratio), Mooney viscosity 87), 2.0 parts by mass of a crosslinking agent (bisphenol AF, manufactured by Central Glass Co., Ltd.), crosslinking Accelerator (BTPPC, manufactured by Hokuko Chemical Co., Ltd.) 1.0 part by mass, magnesium oxide (Kyowa Mag 150, manufactured by Kyowa Chemical Industry Co., Ltd.) 3.0 parts by mass, kneaded using an 18-inch open roll, A full compound of VdF rubber was obtained. This was supplied to a 150 mmφ feeder ruder to obtain a VdF rubber full compound pellet having a diameter of 3 mm and a length of 3 mm.

50 parts by mass of pellets of the above VdF rubber full compound in 50 parts by mass of ETFE (ethylene / TFE = 35/65 (molar ratio), melting point 220 ° C., MFR 30.0 g / 10 min) 15 mmφ biaxial made by Technobel Co., Ltd. The pellets were continuously charged into an extruder and kneaded and extruded at a cylinder temperature of 260 ° C. and a screw rotation speed of 300 rpm to produce composite pellets of a fluororesin and dynamically cross-linked fluororubber.

About the composite of the obtained fluororesin and the dynamically crosslinked fluororubber, the average particle diameter and MFR of the crosslinked fluororubber particles were examined. The average particle size of the crosslinked fluororubber particles was 1.1 μm, and the MFR (297 ° C.) was 4.3 g / 10 minutes.

The obtained composite pellet of fluororesin and dynamically cross-linked fluororubber was supplied to a 15 ton injection molding machine to obtain a wiper blade. Molding temperatures were C-1: 250 ° C, C-2: 270 ° C, C-3: 280 ° C, C-4: 290 ° C, and mold: 130 ° C. The injection time was 7 seconds.
The wiper performance was tested using the obtained wiper blade.

Example 2
A composite of a fluororesin and a dynamically crosslinked fluororubber in the same manner as in Example 1 except that the amount of ETFE charged was 70 parts by mass and the amount of pellets of VdF rubber full compound was 30 parts by mass. Of pellets were produced.

About the composite of the obtained fluororesin and the dynamically crosslinked fluororubber, the average particle diameter and MFR of the crosslinked fluororubber particles were examined. The average particle size of the crosslinked fluororubber particles was 1.0 μm, and the MFR (297 ° C.) was 14.7 g / 10 minutes.

The obtained pellets of a composite of a fluororesin and dynamically cross-linked fluororubber were supplied to a 15 ton injection molding machine to obtain a wiper blade. Molding temperatures were C-1: 250 ° C, C-2: 270 ° C, C-3: 280 ° C, C-4: 290 ° C, and mold: 130 ° C. The injection time was 7 seconds.
Using the obtained wiper blade rubber, a wiper performance test was conducted.

Comparative Example 1
100 parts by mass of binary VdF rubber (VdF / HFP = 78/22 (molar ratio), Mooney viscosity 70), 2.2 parts by mass of a crosslinking agent (bisphenol AF, manufactured by Central Glass Co., Ltd.), a crosslinking accelerator (BTPPC) Hokuko Chemical Industry Co., Ltd.) 0.4 parts by mass, magnesium oxide (Kyowa Mag 150, Kyowa Chemical Industry Co., Ltd.) 3.0 parts by mass, calcium hydroxide (CALDIC 2000, manufactured by Omi Chemical Co., Ltd.) 0 parts by mass and 1.0 part by mass of carbon black (MT carbon: N990, manufactured by Cancarb) were kneaded using an 18-inch open roll to obtain a full compound of VdF rubber.

Thereafter, it was molded into the shape of a wiper blade rubber in a molding die, and crosslinked at 180 ° C. for 5 minutes under a pressure of 40 kg / cm ² to obtain a crosslinked molded product.
Thereafter, the crosslinked molded article was placed in a heating furnace maintained at 230 ° C. for 24 hours and subjected to a heat treatment to obtain a wiper blade rubber.
Using the obtained wiper blade rubber, a wiper performance test was conducted.

The wiper blade rubber of the present invention is excellent in low friction properties and exhibits excellent wiping properties, and can be used as wiper blades for various vehicles and machine tool machines.

10: Wiper blade rubber 11: Head portion 12: Bridge portion 13: Wedge portion 14: Wiper edge portion 15: Glass

Claims (4)

A wiper blade rubber comprising a composite of a fluororesin and a dynamically crosslinked fluororubber. The fluororesin is a non-perfluoro resin,
The wiper blade rubber according to claim 1, wherein the fluororubber is a vinylidene fluoride / hexafluoropropylene copolymer or a vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene copolymer. The wiper blade rubber according to claim 1 or 2, wherein the fluororesin is an ethylene / tetrafluoroethylene copolymer. The wiper according to claim 1, 2 or 3, wherein the composite of the fluororesin and the dynamically crosslinked fluororubber is 5 to 500 parts by mass of the dynamically crosslinked fluororubber with respect to 100 parts by mass of the fluororesin. Blade rubber.

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