JP2017095539A - Magnetic rubber composition, magnetic rubber molded article, magnetic encoder and manufacturing method therefor - Google Patents
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- 229920001971 elastomer Polymers 0.000 title claims abstract description 156
- 239000005060 rubber Substances 0.000 title claims abstract description 156
- 239000000203 mixture Substances 0.000 title claims abstract description 84
- 238000004519 manufacturing process Methods 0.000 title claims description 11
- 239000006247 magnetic powder Substances 0.000 claims abstract description 83
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 66
- 229920000459 Nitrile rubber Polymers 0.000 claims abstract description 35
- 235000021355 Stearic acid Nutrition 0.000 claims abstract description 27
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 claims abstract description 27
- OQCDKBAXFALNLD-UHFFFAOYSA-N octadecanoic acid Natural products CCCCCCCC(C)CCCCCCCCC(O)=O OQCDKBAXFALNLD-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000008117 stearic acid Substances 0.000 claims abstract description 27
- 238000004073 vulcanization Methods 0.000 claims description 27
- 239000003795 chemical substances by application Substances 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 15
- 230000006835 compression Effects 0.000 claims description 10
- 238000007906 compression Methods 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 10
- 238000009826 distribution Methods 0.000 claims description 7
- 239000000843 powder Substances 0.000 abstract 3
- 230000004907 flux Effects 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 10
- 238000002156 mixing Methods 0.000 description 10
- 239000000853 adhesive Substances 0.000 description 8
- 230000001070 adhesive effect Effects 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 8
- 229920001187 thermosetting polymer Polymers 0.000 description 6
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 4
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 4
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 4
- 238000001514 detection method Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000001771 impaired effect Effects 0.000 description 4
- 229910052740 iodine Inorganic materials 0.000 description 4
- 239000011630 iodine Substances 0.000 description 4
- 238000004898 kneading Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 239000004636 vulcanized rubber Substances 0.000 description 4
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 3
- 238000000748 compression moulding Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000000465 moulding Methods 0.000 description 3
- 229910052712 strontium Inorganic materials 0.000 description 3
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 239000011593 sulfur Substances 0.000 description 3
- 239000006087 Silane Coupling Agent Substances 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- AFZSMODLJJCVPP-UHFFFAOYSA-N dibenzothiazol-2-yl disulfide Chemical compound C1=CC=C2SC(SSC=3SC4=CC=CC=C4N=3)=NC2=C1 AFZSMODLJJCVPP-UHFFFAOYSA-N 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000005011 phenolic resin Substances 0.000 description 2
- 239000004014 plasticizer Substances 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 150000002910 rare earth metals Chemical class 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000009864 tensile test Methods 0.000 description 2
- ARCGXLSVLAOJQL-UHFFFAOYSA-N trimellitic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C(C(O)=O)=C1 ARCGXLSVLAOJQL-UHFFFAOYSA-N 0.000 description 2
- -1 2-ethylhexyl Chemical group 0.000 description 1
- 239000004808 2-ethylhexylester Substances 0.000 description 1
- UJAWGGOCYUPCPS-UHFFFAOYSA-N 4-(2-phenylpropan-2-yl)-n-[4-(2-phenylpropan-2-yl)phenyl]aniline Chemical compound C=1C=C(NC=2C=CC(=CC=2)C(C)(C)C=2C=CC=CC=2)C=CC=1C(C)(C)C1=CC=CC=C1 UJAWGGOCYUPCPS-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- KRADHMIOFJQKEZ-UHFFFAOYSA-N Tri-2-ethylhexyl trimellitate Chemical compound CCCCC(CC)COC(=O)C1=CC=C(C(=O)OCC(CC)CCCC)C(C(=O)OCC(CC)CCCC)=C1 KRADHMIOFJQKEZ-UHFFFAOYSA-N 0.000 description 1
- 239000007983 Tris buffer Substances 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000003712 anti-aging effect Effects 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- CSNJTIWCTNEOSW-UHFFFAOYSA-N carbamothioylsulfanyl carbamodithioate Chemical compound NC(=S)SSC(N)=S CSNJTIWCTNEOSW-UHFFFAOYSA-N 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- AUZONCFQVSMFAP-UHFFFAOYSA-N disulfiram Chemical compound CCN(CC)C(=S)SSC(=S)N(CC)CC AUZONCFQVSMFAP-UHFFFAOYSA-N 0.000 description 1
- 235000012489 doughnuts Nutrition 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 150000004678 hydrides Chemical class 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 238000005984 hydrogenation reaction Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000011344 liquid material Substances 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- AJCDFVKYMIUXCR-UHFFFAOYSA-N oxobarium;oxo(oxoferriooxy)iron Chemical compound [Ba]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O.O=[Fe]O[Fe]=O AJCDFVKYMIUXCR-UHFFFAOYSA-N 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000010734 process oil Substances 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 239000000700 radioactive tracer Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000011342 resin composition Substances 0.000 description 1
- 238000013040 rubber vulcanization Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 229920002803 thermoplastic polyurethane Polymers 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/20—Oxides; Hydroxides
- C08K3/22—Oxides; Hydroxides of metals
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L15/00—Compositions of rubber derivatives
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/244—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
- G01D5/245—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains using a variable number of pulses in a train
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F7/00—Magnets
- H01F7/02—Permanent magnets [PM]
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- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Transmission And Conversion Of Sensor Element Output (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
- Manufacturing Cores, Coils, And Magnets (AREA)
Abstract
Description
本発明は、水素化ニトリルゴム、フェライト磁性粉、加硫剤及びステアリン酸を含有する磁性ゴム組成物及びそれを加硫してなる磁性ゴム成形品に関する。また、当該磁性ゴム成形品を備えた磁気エンコーダに関する。さらに、磁性ゴム成形品及び磁気エンコーダの製造方法に関する。 The present invention relates to a magnetic rubber composition containing hydrogenated nitrile rubber, ferrite magnetic powder, a vulcanizing agent and stearic acid, and a magnetic rubber molded product obtained by vulcanizing the magnetic rubber composition. The present invention also relates to a magnetic encoder provided with the magnetic rubber molded product. Furthermore, it is related with the manufacturing method of a magnetic rubber molded product and a magnetic encoder.
ゴムと磁性粉を含む磁性ゴム組成物を加硫させて得られる磁性ゴム成形品は、様々な用途に用いられている。中でも磁性ゴム成形品の好適な用途の一つが磁気エンコーダであり、磁性ゴム成形品を着磁させることによって製造される。このとき、製品の要求性能に対応して様々なゴムが用いられるが、耐油性や耐熱性、価格などのバランスからニトリルゴム（ＮＢＲ）や水素化ニトリルゴム（ＨＮＢＲ）が好適に用いられる。また磁性粉としては、フェライト磁性粉や希土類磁性粉などが要求性能に応じて使い分けられているが、コストや耐久性の観点からフェライト磁性粉が広く用いられている。 Magnetic rubber molded articles obtained by vulcanizing a magnetic rubber composition containing rubber and magnetic powder are used in various applications. Among them, one of the preferable uses of the magnetic rubber molded product is a magnetic encoder, which is manufactured by magnetizing the magnetic rubber molded product. At this time, various rubbers are used in accordance with the required performance of the product, but nitrile rubber (NBR) and hydrogenated nitrile rubber (HNBR) are preferably used from the balance of oil resistance, heat resistance, price and the like. As magnetic powder, ferrite magnetic powder, rare earth magnetic powder, and the like are properly used according to required performance, but ferrite magnetic powder is widely used from the viewpoint of cost and durability.
磁気エンコーダを用いた各種センサの精度向上や小型化のために、磁性ゴム成形品の磁気特性の向上が強く求められている。これまで、磁性粉を大量に配合することによって磁気特性を向上させることが試されてきたが、配合量が多すぎると成形性が低下してしまうので、配合量の向上にも限界があった。そのため、成形性を確保しながら磁性粉の配合量を増加させ、成形品の磁気特性を向上させることのできる磁性ゴム成形品が求められてきた。 In order to improve the accuracy and miniaturization of various sensors using a magnetic encoder, there is a strong demand for improving the magnetic properties of magnetic rubber molded products. Up to now, attempts have been made to improve magnetic properties by blending a large amount of magnetic powder. However, if the blending amount is too large, the moldability deteriorates, so there is a limit to improving the blending amount. . Therefore, there has been a demand for a magnetic rubber molded product that can increase the blending amount of magnetic powder while improving moldability and improve the magnetic properties of the molded product.
例えば、特許文献１及び２には、ＮＢＲに多量のフェライト磁性粉を配合した磁性ゴム組成物が記載されていて、それらが磁気エンコーダに適していることも記載されている。これらの文献では、固形ＮＢＲ１００重量部に対して、１１４３重量部（特許文献１の実施例３）、１７００重量部（特許文献２のＮｏ．２３及び２４）のフェライト磁性粉を配合した例が示されていて、分子量の低い液状ＮＢＲやプロセスオイルを併用することによって成形性を確保している。しかしながら、固形ＮＢＲの代わりにこれらの液状物を配合したのでは機械特性が悪化してしまうし、磁性ゴム組成物全体に対するフェライト磁性粉の含有率も低下してしまう（特許文献１の実施例３では８７．４重量％、特許文献２のＮｏ．２３及び２４では９０．７重量％）。 For example, Patent Documents 1 and 2 describe magnetic rubber compositions in which a large amount of ferrite magnetic powder is blended with NBR, and it is also described that these are suitable for magnetic encoders. These documents show an example in which 1143 parts by weight (Example 3 of Patent Document 1) and 1700 parts by weight (Nos. 23 and 24 of Patent Document 2) of ferrite magnetic powder are blended with 100 parts by weight of solid NBR. In addition, moldability is ensured by using liquid NBR or process oil having a low molecular weight in combination. However, if these liquid materials are blended in place of solid NBR, mechanical properties are deteriorated, and the content of ferrite magnetic powder relative to the entire magnetic rubber composition is also reduced (Example 3 of Patent Document 1). 87.4 wt%, and No. 23 and 24 of Patent Document 2 are 90.7 wt%).
磁性ゴム成形品の耐熱老化性や耐薬品性などを向上させたい場合には、水素添加されていないＮＢＲではなく、水素添加されたＨＮＢＲが用いられる。例えば、特許文献３及び４には、ＨＮＢＲに多量のフェライト磁性粉を配合した磁性ゴム組成物が記載されていて、特許文献３には磁気エンコーダに適していることも記載されている。特許文献３の磁性ゴム組成物では、ＨＮＢＲとフェライト磁性粉との相互作用を改善するためにシランカップリング剤が配合されているが、磁性ゴム組成物全体に対するフェライト磁性粉の含有率は８７．１〜８８．０重量％であり（実施例１〜６）、磁気特性が不十分であった。また、特許文献４の磁性ゴム組成物では、アルコキシシランを配合することによって粘度を低下させるとともに磁気特性を向上させたことが記載されているが、磁性ゴム組成物全体に対するフェライト磁性粉の含有率は９０．１重量％であり（実施例１）、やはり磁気特性が不十分であった。 When it is desired to improve the heat aging resistance and chemical resistance of the magnetic rubber molded product, hydrogenated HNBR is used instead of non-hydrogenated NBR. For example, Patent Documents 3 and 4 describe a magnetic rubber composition in which a large amount of ferrite magnetic powder is blended with HNBR, and Patent Document 3 also describes that it is suitable for a magnetic encoder. In the magnetic rubber composition of Patent Document 3, a silane coupling agent is blended in order to improve the interaction between HNBR and ferrite magnetic powder, but the content of ferrite magnetic powder relative to the entire magnetic rubber composition is 87. 1 to 88.0% by weight (Examples 1 to 6), and the magnetic properties were insufficient. Moreover, in the magnetic rubber composition of patent document 4, although it described that the viscosity was reduced and the magnetic characteristic was improved by mix | blending alkoxysilane, the content rate of the ferrite magnetic powder with respect to the whole magnetic rubber composition Was 90.1% by weight (Example 1), and the magnetic properties were still insufficient.
特許文献５には、ニトリルゴム（水素化物を含む）１００重量部に対して、圧縮密度が３．４〜３．７ｇ／ｃｍ３のフェライト磁性粉を１０００〜１２００重量部含有するニトリルゴム系組成物が記載されている。その実施例７には、ＨＮＢＲを用いた例も記載されていて、ムーニー粘度（ＭＬ１＋４、１００℃）が２９のＨＮＢＲ１００重量部に、圧縮密度が３．５９で粒度分布において複数のピークを有するフェライト磁性粉１０００重量部、硫黄２重量部及びステアリン酸２重量部を配合した磁性ゴム組成物が記載されている。しかしながら、磁性ゴム組成物全体に対するフェライト磁性粉の含有率は８９．２重量％であり、磁気特性が不十分であった。また、低粘度のＨＮＢＲを用いているために機械特性も十分ではなかった。 Patent Document 5 discloses a nitrile rubber-based composition containing 1000 to 1200 parts by weight of ferrite magnetic powder having a compression density of 3.4 to 3.7 g / cm 3 with respect to 100 parts by weight of nitrile rubber (including hydride). Things are listed. In Example 7, an example using HNBR is also described, in which 100 parts by weight of HNBR having a Mooney viscosity (ML 1 + 4 , 100 ° C.) of 29, a compression density of 3.59, and a plurality of peaks in the particle size distribution are included. A magnetic rubber composition containing 1000 parts by weight of ferrite magnetic powder, 2 parts by weight of sulfur and 2 parts by weight of stearic acid is described. However, the content of ferrite magnetic powder with respect to the entire magnetic rubber composition was 89.2% by weight, and the magnetic properties were insufficient. Further, since the low-viscosity HNBR is used, the mechanical properties are not sufficient.
以上のように、ＨＮＢＲ（あるいはＮＢＲ）を含む磁性ゴム組成物の磁気特性を向上させるために、フェライト磁性粉の含有率を向上させる努力がこれまで長期間にわたって継続されてきた。しかしながら、磁性ゴム組成物全体に対するフェライト磁性粉の含有率が９１質量％以上であって、しかも成形性の良好な磁性ゴム組成物はこれまで知られていない。 As described above, in order to improve the magnetic properties of the magnetic rubber composition containing HNBR (or NBR), efforts to improve the content of ferrite magnetic powder have been continued for a long time. However, a magnetic rubber composition having a ferrite magnetic powder content of 91% by mass or more based on the whole magnetic rubber composition and having good moldability has not been known so far.
本発明は、上記課題を解決するためになされたものであり、極めて高濃度の磁性粉を含有しながらも流動性に優れた磁性ゴム組成物を提供することを目的とするものである。また、当該磁性ゴム組成物を加硫することによって、非常に優れた磁気特性と良好な機械特性とを兼ね備えた磁性ゴム成形品を提供すること、及び該磁性ゴム成形品を備えた磁気エンコーダを提供することも本発明の目的である。さらに、前記磁性ゴム成形品及び磁気エンコーダの好適な製造方法を提供することも本発明の目的である。 The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a magnetic rubber composition having excellent fluidity while containing a very high concentration of magnetic powder. Also, by vulcanizing the magnetic rubber composition, a magnetic rubber molded product having both excellent magnetic properties and good mechanical properties is provided, and a magnetic encoder provided with the magnetic rubber molded product is provided. Providing is also an object of the present invention. Furthermore, it is also an object of the present invention to provide a suitable method for manufacturing the magnetic rubber molded product and the magnetic encoder.
上記課題は、水素化ニトリルゴム（Ａ）、フェライト磁性粉（Ｂ）、加硫剤（Ｃ）及びステアリン酸（Ｄ）を含有する磁性ゴム組成物であって、
水素化ニトリルゴム（Ａ）のムーニー粘度（ＭＬ１＋４、１００℃）が４５〜８０であり、
水素化ニトリルゴム（Ａ）１００質量部に対し、フェライト磁性粉（Ｂ）１２５０〜１６００質量部、加硫剤（Ｃ）０．１〜４質量部及びステアリン酸（Ｄ）２．５〜８質量部を含有し、
前記磁性ゴム組成物全体の質量に対するフェライト磁性粉（Ｂ）の含有率が９１〜９３質量％であることを特徴とする磁性ゴム組成物を提供することによって解決される。
The above problem is a magnetic rubber composition containing hydrogenated nitrile rubber (A), ferrite magnetic powder (B), vulcanizing agent (C) and stearic acid (D),
The Mooney viscosity (ML 1 + 4 , 100 ° C.) of the hydrogenated nitrile rubber (A) is 45-80,
Ferrite magnetic powder (B) 1250 to 1600 parts by mass, vulcanizing agent (C) 0.1 to 4 parts by mass and stearic acid (D) 2.5 to 8 parts by mass with respect to 100 parts by mass of hydrogenated nitrile rubber (A). Part
The problem is solved by providing a magnetic rubber composition characterized in that the content of ferrite magnetic powder (B) is 91 to 93% by mass with respect to the mass of the entire magnetic rubber composition.
このとき、フェライト磁性粉（Ｂ）の圧縮密度が３．５ｇ／ｃｍ３以上であることが好ましく、その粒度分布において複数のピークを有することも好ましい。前記磁性ゴム組成物全体の、１８０℃における加硫曲線を測定した際のトルクの最小値ＭＬが、３〜７ｋｇｆ・ｃｍであることも好ましい。また、本発明の磁性ゴム組成物が、磁気エンコーダ用であることも好ましい。 At this time, the compression density of the ferrite magnetic powder (B) is preferably 3.5 g / cm 3 or more, and it is also preferable to have a plurality of peaks in the particle size distribution. It is also preferable that the minimum value ML of the torque when the vulcanization curve at 180 ° C. of the entire magnetic rubber composition is measured is 3 to 7 kgf · cm. It is also preferred that the magnetic rubber composition of the present invention is for a magnetic encoder.
本発明の好適な実施態様は、前記磁性ゴム組成物を加硫してなる磁性ゴム成形品であり、当該磁性ゴム成形品を備えた磁気エンコーダである。 A preferred embodiment of the present invention is a magnetic rubber molded article obtained by vulcanizing the magnetic rubber composition, and a magnetic encoder provided with the magnetic rubber molded article.
上記課題は、水素化ニトリルゴム（Ａ）、フェライト磁性粉（Ｂ）、加硫剤（Ｃ）及びステアリン酸（Ｄ）を混合して前記磁性ゴム組成物を得てから、該磁性ゴム組成物を加硫する、前記磁性ゴム成形品の製造方法を提供することによっても解決される。このとき、前記磁性ゴム組成物を磁場の印加された金型中で加硫することが好適である。また上記課題は、前記磁性ゴム成形品を所定のパターンに着磁させる磁気エンコーダの製造方法を提供することによっても解決される。 The object is to obtain the magnetic rubber composition by mixing the hydrogenated nitrile rubber (A), the ferrite magnetic powder (B), the vulcanizing agent (C) and the stearic acid (D), and then the magnetic rubber composition. This can also be solved by providing a method for producing the magnetic rubber molded article. At this time, it is preferable to vulcanize the magnetic rubber composition in a mold to which a magnetic field is applied. The above-described problem can also be solved by providing a method for manufacturing a magnetic encoder that magnetizes the magnetic rubber molded product in a predetermined pattern.
本発明の磁性ゴム組成物は、極めて高濃度の磁性粉を含有しながらも流動性に優れている。したがって、その磁性ゴム組成物を成形してなる磁性ゴム成形品は、非常に優れた磁気特性と良好な機械特性とを兼ね備えていて、高性能の磁気エンコーダーを提供することができる。また、本発明の製造方法によれば、高性能の磁性ゴム成形品及び磁気エンコーダを製造することができる。 The magnetic rubber composition of the present invention is excellent in fluidity while containing an extremely high concentration of magnetic powder. Therefore, a magnetic rubber molded product obtained by molding the magnetic rubber composition has both excellent magnetic characteristics and good mechanical characteristics, and can provide a high-performance magnetic encoder. Moreover, according to the manufacturing method of the present invention, a high-performance magnetic rubber molded product and a magnetic encoder can be manufactured.
本発明の磁性ゴム組成物は、水素化ニトリルゴム（ＨＮＢＲ）（Ａ）、フェライト磁性粉（Ｂ）、加硫剤（Ｃ）及びステアリン酸（Ｄ）を含有する磁性ゴム組成物であって、
ＨＮＢＲ（Ａ）のムーニー粘度（ＭＬ１＋４、１００℃）が４５〜８０であり、
ＨＮＢＲ（Ａ）１００質量部に対し、フェライト磁性粉（Ｂ）１２５０〜１６００質量部、加硫剤（Ｃ）０．１〜４質量部及びステアリン酸（Ｄ）２．５〜８質量部を含有し、
前記磁性ゴム組成物全体の質量に対するフェライト磁性粉（Ｂ）の含有率が９１〜９３質量％であることを特徴とする磁性ゴム組成物である。
The magnetic rubber composition of the present invention is a magnetic rubber composition containing hydrogenated nitrile rubber (HNBR) (A), ferrite magnetic powder (B), vulcanizing agent (C) and stearic acid (D),
HNBR (A) has a Mooney viscosity (ML 1 + 4 , 100 ° C.) of 45 to 80,
Contains 1250 to 1600 parts by mass of ferrite magnetic powder (B), 0.1 to 4 parts by mass of vulcanizing agent (C), and 2.5 to 8 parts by mass of stearic acid (D) with respect to 100 parts by mass of HNBR (A). And
The magnetic rubber composition is characterized in that the content of the ferrite magnetic powder (B) with respect to the total mass of the magnetic rubber composition is 91 to 93% by mass.
このような構成の磁性ゴム組成物とすることによって、磁性ゴム組成物全体の質量に対するフェライト磁性粉（Ｂ）の含有率が９１〜９３質量％であるという、極めて高濃度のフェライト磁性粉（Ｂ）を含みながらも、流動性の良好な磁性ゴム組成物を得ることができた。この磁性ゴム組成物を加硫することによって、非常に優れた磁気特性と良好な機械特性とを兼ね備えた磁性ゴム成形品を成形性良く製造することができる。ここで、磁性ゴム組成物がＮＢＲではなくＨＮＢＲを含むことによって、後の実施例にも示されているように、その流動性が向上し、得られる磁性ゴム成形品の磁気特性が向上することがわかった。以下、本発明の磁性ゴム組成物について詳細に説明する。 By using the magnetic rubber composition having such a configuration, a ferrite magnetic powder (B ), A magnetic rubber composition having good fluidity could be obtained. By vulcanizing this magnetic rubber composition, it is possible to produce a magnetic rubber molded product having excellent magnetic properties and good mechanical properties with good moldability. Here, when the magnetic rubber composition contains HNBR instead of NBR, the fluidity is improved and the magnetic properties of the obtained magnetic rubber molded article are improved as shown in the following examples. I understood. Hereinafter, the magnetic rubber composition of the present invention will be described in detail.
本発明の磁性ゴム組成物は、水素化ニトリルゴム（ＨＮＢＲ）（Ａ）を含有する。本発明で用いられるＨＮＢＲ（Ａ）は特に限定されず、アクリロニトリルと１，３−ブタジエンの共重合体を水素添加したものを用いることができる。水素添加に際しては、重合後の１，３−ブタジエン単位に残存する二重結合に対して水素が付加する。ＨＮＢＲ（Ａ）のヨウ素価は８０ｇ／１００ｇ以下であることが好ましい。ヨウ素価が大きすぎると、耐熱老化性や耐薬品性が低下することがある。ヨウ素価は、より好適には６０ｇ／１００ｇ以下であり、さらに好適には３０ｇ／１００ｇ以下である。 The magnetic rubber composition of the present invention contains hydrogenated nitrile rubber (HNBR) (A). HNBR (A) used in the present invention is not particularly limited, and a hydrogenated copolymer of acrylonitrile and 1,3-butadiene can be used. In the hydrogenation, hydrogen is added to the double bond remaining in the 1,3-butadiene unit after polymerization. The iodine value of HNBR (A) is preferably 80 g / 100 g or less. If the iodine value is too large, heat aging resistance and chemical resistance may be lowered. The iodine value is more preferably 60 g / 100 g or less, and further preferably 30 g / 100 g or less.
ＨＮＢＲ（Ａ）中のアクリロニトリル単位の含有量は、１５〜５０質量％であることが好ましい。また、１，３−ブタジエン単位の含有量は水添されたものも含めて、５０〜８５質量％であることが好ましい。本発明の効果を阻害しない範囲であれば、他の共重合可能な単量体由来の構成単位を含んでいても構わないが、通常その含有量は１０質量％以下であり、好適には５質量％以下である。 The content of acrylonitrile units in HNBR (A) is preferably 15 to 50% by mass. Moreover, it is preferable that content of a 1, 3- butadiene unit is 50-85 mass% including what was hydrogenated. As long as the effect of the present invention is not impaired, it may contain a constitutional unit derived from another copolymerizable monomer, but its content is usually 10% by mass or less, preferably 5 It is below mass%.
ＨＮＢＲ（Ａ）のムーニー粘度（ＭＬ１＋４、１００℃）は４５〜８０である。多量の磁性粉を含みながらも良好な流動性を維持するためには、ムーニー粘度が８０以下であることが必要であり、７０以下であることが好ましい。一方、ムーニー粘度が４５未満であると、加硫して得られる磁性ゴム成形品の機械特性が不十分となる。 The Mooney viscosity (ML 1 + 4 , 100 ° C.) of HNBR (A) is 45-80. In order to maintain good fluidity while including a large amount of magnetic powder, the Mooney viscosity needs to be 80 or less, and preferably 70 or less. On the other hand, if the Mooney viscosity is less than 45, the mechanical properties of the magnetic rubber molded product obtained by vulcanization will be insufficient.
本発明の磁性ゴム組成物は、フェライト磁性粉（Ｂ）を含有する。ここで用いられるフェライト磁性粉（Ｂ）は特に限定されず、ストロンチウムフェライト磁性粉やバリウムフェライト磁性粉が好適に用いられる。フェライト磁性粉（Ｂ）の圧縮密度は特に限定されないが、３．５ｇ／ｃｍ３以上であることが好ましく、３．５５ｇ／ｃｍ３以上であることがより好ましい。これによって、より高濃度の磁性粉を含有しながらも流動性に優れた磁性ゴム組成物を得ることができ、それを加硫することで、さらに優れた磁気特性を有する磁性ゴム成形品を得ることができる。フェライト磁性粉（Ｂ）圧縮密度は、通常４ｇ／ｃｍ３以下である。 The magnetic rubber composition of the present invention contains a ferrite magnetic powder (B). The ferrite magnetic powder (B) used here is not particularly limited, and strontium ferrite magnetic powder and barium ferrite magnetic powder are preferably used. While compressed density of the ferrite magnetic powder (B) is not particularly limited, it is preferably 3.5 g / cm 3 or more, and more preferably 3.55 g / cm 3 or more. As a result, a magnetic rubber composition excellent in fluidity can be obtained while containing a higher concentration of magnetic powder, and by vulcanizing it, a magnetic rubber molded product having further excellent magnetic properties can be obtained. be able to. The ferrite magnetic powder (B) compression density is usually 4 g / cm 3 or less.
ここで、フェライト磁性粉（Ｂ）の圧縮密度（ｇ／ｃｍ３）は、内径２．５４ｃｍの円筒形の金型に、フェライト磁性粉１０ｇを充填した後に、１ｔｏｎ／ｃｍ２の圧力で圧縮した試料の密度である。このような圧縮密度を有するためには、粒度分布において複数のピークを有するものであることが好ましい。フェライト磁性粉（Ｂ）の粒度分布は、乾式レーザー回折式粒度分布測定装置を用いて測定することができる。フェライト磁性粉（Ｂ）の平均粒径は０．５〜２μｍであることが好ましい。 Here, the compression density (g / cm 3 ) of the ferrite magnetic powder (B) was compressed at a pressure of 1 ton / cm 2 after filling a cylindrical mold having an inner diameter of 2.54 cm with 10 g of ferrite magnetic powder. It is the density of the sample. In order to have such a compression density, it is preferable to have a plurality of peaks in the particle size distribution. The particle size distribution of the ferrite magnetic powder (B) can be measured using a dry laser diffraction particle size distribution measuring apparatus. The average particle size of the ferrite magnetic powder (B) is preferably 0.5 to 2 μm.
また、フェライト磁性粉（Ｂ）は異方性磁性粉であることが好ましい。異方性磁性粉を用いて、磁場の印加された金型中で加硫することによって、磁気特性に優れた磁性ゴム成形品を得ることができる。本発明の磁性ゴム組成物は、極めて高濃度の磁性粉を含有しながらも流動性に優れているので、磁場の印加された金型中で加硫される際に、フェライト磁性粉（Ｂ）が十分に配向することができ、非常に優れた磁気特性を有する磁性ゴム成形品を得ることができる。このような加硫方法に適した異方性磁性粉は、一般に「磁場配向用」として市販されている。磁場配向用の磁性粉は、磁場を印加した際にゴム組成物中で容易に回転できるように、そのアスペクト比（板状体における（直径／厚み）比）が小さいものである。一方、磁場を印加せずに機械的変形に伴って配向させる方法に対しては、一般に「機械配向用」として市販されているアスペクト比の大きいものが用いられる。本発明では、上記「磁場配向用」のフェライト磁性粉を用いることが好ましい。 The ferrite magnetic powder (B) is preferably an anisotropic magnetic powder. By using an anisotropic magnetic powder and vulcanizing in a mold to which a magnetic field is applied, a magnetic rubber molded product having excellent magnetic properties can be obtained. Since the magnetic rubber composition of the present invention contains an extremely high concentration of magnetic powder and has excellent fluidity, the ferrite magnetic powder (B) is used when vulcanized in a mold to which a magnetic field is applied. Can be sufficiently oriented, and a magnetic rubber molded article having very excellent magnetic properties can be obtained. Anisotropic magnetic powder suitable for such a vulcanization method is generally marketed as “for magnetic field orientation”. The magnetic powder for magnetic field orientation has a small aspect ratio ((diameter / thickness) ratio in the plate-like body) so that it can be easily rotated in the rubber composition when a magnetic field is applied. On the other hand, as a method of aligning with mechanical deformation without applying a magnetic field, a method having a large aspect ratio generally marketed as “for mechanical alignment” is used. In the present invention, it is preferable to use the above “magnetic field orientation” ferrite magnetic powder.
本発明の磁性ゴム組成物における、ＨＮＢＲ（Ａ）１００質量部に対するフェライト磁性粉（Ｂ）の含有量は１２５０〜１６００質量部である。フェライト磁性粉（Ｂ）の含有量が１２５０質量部以上であることによって、優れた磁気特性を有する磁性ゴム成形品を得ることができる。フェライト磁性粉（Ｂ）の含有量は、好適には１３００質量部以上であり、より好適には１３２０質量部以上である。一方、フェライト磁性粉（Ｂ）の含有量が１６００質量部を超えると、成形性が悪化し、金型への充填不良が発生したり、得られる磁性ゴム成形品の強度が低下する。フェライト磁性粉（Ｂ）の含有量は、好適には１５００質量部以下である。 In the magnetic rubber composition of the present invention, the content of the ferrite magnetic powder (B) with respect to 100 parts by mass of HNBR (A) is 1250 to 1600 parts by mass. When the content of the ferrite magnetic powder (B) is 1250 parts by mass or more, a magnetic rubber molded product having excellent magnetic properties can be obtained. The content of the ferrite magnetic powder (B) is preferably 1300 parts by mass or more, and more preferably 1320 parts by mass or more. On the other hand, when the content of the ferrite magnetic powder (B) exceeds 1600 parts by mass, the moldability deteriorates, poor filling into the mold occurs, and the strength of the obtained magnetic rubber molded product decreases. The content of the ferrite magnetic powder (B) is preferably 1500 parts by mass or less.
本発明の磁性ゴム組成物は、本発明の効果を阻害しない範囲であれば、ＨＮＢＲ（Ａ）以外のゴムを含んでも構わない。しかしながらその含有量は、通常ゴム成分全量のうちの１０質量％以下であり、５質量％以下であることが好ましく、ＨＮＢＲ（Ａ）以外のゴムを実質的に含まないことがより好ましい。また、本発明の磁性ゴム組成物は、本発明の効果を阻害しない範囲であれば、フェライト磁性粉（Ｂ）以外の磁性粉、例えば希土類磁性粉を含んでいても構わない。しかしながらその含有量は、通常、磁性粉全量のうちの１０質量％以下であり、５質量％以下であることが好ましく、フェライト磁性粉（Ｂ）以外の磁性粉を実質的に含まないことがより好ましい。 The magnetic rubber composition of the present invention may contain a rubber other than HNBR (A) as long as the effects of the present invention are not impaired. However, the content is usually 10% by mass or less of the total amount of rubber components, preferably 5% by mass or less, and more preferably substantially free of rubber other than HNBR (A). In addition, the magnetic rubber composition of the present invention may contain magnetic powder other than the ferrite magnetic powder (B), for example, rare earth magnetic powder, as long as the effects of the present invention are not impaired. However, the content is usually 10% by mass or less of the total amount of magnetic powder, preferably 5% by mass or less, and substantially free of magnetic powder other than ferrite magnetic powder (B). preferable.
本発明の磁性ゴム組成物は、加硫剤（Ｃ）を含む。加硫剤（Ｃ）としては、硫黄、過酸化物など、ＨＮＢＲ（Ａ）の加硫に通常用いられるものを採用することができる。加硫剤（Ｃ）の含有量は、ＨＮＢＲ（Ａ）１００質量部に対して、０．１〜４質量部である。加硫剤（Ｃ）の含有量が０．１質量部未満の場合、加硫時間が長くなるとともに、得られる磁性ゴム成形品の機械特性が悪化する。加硫剤（Ｃ）の含有量は、好適には０．２質量部以上である。一方、加硫剤（Ｃ）の含有量が４質量部を超える場合、得られる磁性ゴム成形品の機械特性が悪化する。加硫剤（Ｃ）の含有量は、好適には２質量部以下である。 The magnetic rubber composition of the present invention contains a vulcanizing agent (C). As the vulcanizing agent (C), those usually used for vulcanizing HNBR (A) such as sulfur and peroxide can be employed. Content of a vulcanizing agent (C) is 0.1-4 mass parts with respect to 100 mass parts of HNBR (A). When the content of the vulcanizing agent (C) is less than 0.1 parts by mass, the vulcanization time becomes longer and the mechanical properties of the obtained magnetic rubber molded product are deteriorated. The content of the vulcanizing agent (C) is preferably 0.2 parts by mass or more. On the other hand, when the content of the vulcanizing agent (C) exceeds 4 parts by mass, the mechanical properties of the obtained magnetic rubber molded product deteriorate. The content of the vulcanizing agent (C) is preferably 2 parts by mass or less.
本発明の磁性ゴム組成物は、ステアリン酸（Ｄ）を含む。ステアリン酸（Ｄ）は、通常加硫助剤として配合されるものであるが、通常よりも多量のステアリン酸（Ｄ）を配合することで、大量の磁性粉を配合しても良好な流動性を維持することができ、その結果、極めて優れた磁気特性を有するとともに機械特性にも優れた磁性ゴム成形品を得ることができる。ステアリン酸（Ｄ）の含有量は、ＨＮＢＲ（Ａ）１００質量部に対して、２．５〜８質量部である。ステアリン酸（Ｄ）の含有量が２．５質量部未満の場合、流動性が悪化するとともに、得られる磁性ゴム成形品の磁気特性も悪化する。ステアリン酸（Ｄ）の含有量は、好適には３質量部以上、より好適には３．２質量部以上である。一方、ステアリン酸（Ｄ）の含有量が８質量部を超える場合、得られる磁性ゴム成形品の機械特性が悪化する。ステアリン酸（Ｄ）の含有量は、好適には６質量部以下であり、より好適には５質量部以下である。 The magnetic rubber composition of the present invention contains stearic acid (D). Stearic acid (D) is usually blended as a vulcanization aid, but by blending a larger amount of stearic acid (D) than usual, good fluidity even when blending a large amount of magnetic powder. As a result, it is possible to obtain a magnetic rubber molded product having extremely excellent magnetic properties and excellent mechanical properties. The content of stearic acid (D) is 2.5 to 8 parts by mass with respect to 100 parts by mass of HNBR (A). When the content of stearic acid (D) is less than 2.5 parts by mass, the fluidity is deteriorated and the magnetic properties of the obtained magnetic rubber molded article are also deteriorated. The content of stearic acid (D) is preferably 3 parts by mass or more, and more preferably 3.2 parts by mass or more. On the other hand, when the content of stearic acid (D) exceeds 8 parts by mass, the mechanical properties of the obtained magnetic rubber molded article deteriorate. The content of stearic acid (D) is preferably 6 parts by mass or less, and more preferably 5 parts by mass or less.
本発明の磁性ゴム組成物においては、磁性ゴム組成物全体の質量に対するフェライト磁性粉（Ｂ）の含有率が９１〜９３質量％である。このような高いフェライト磁性粉（Ｂ）の含有率を有しながらも、流動性が良好であるところが、本発明の磁性ゴム組成物の大きな特徴である。そして、このような磁性ゴム組成物を加硫してなる磁性ゴム成形品は、極めて高い残留磁束密度を有するとともに良好な機械特性も有している。フェライト磁性粉（Ｂ）の含有率が９１質量％未満である場合、残留磁束密度が低下する。フェライト磁性粉（Ｂ）の含有率は、好適には９１．３質量％以上であり、より好適には９１．６質量％以上である。一方、フェライト磁性粉（Ｂ）の含有率が９３質量％を超える場合、成形性が悪化し、金型への充填不良が発生したり、得られる磁性ゴム成形品の強度が低下する。 In the magnetic rubber composition of the present invention, the content of the ferrite magnetic powder (B) with respect to the total mass of the magnetic rubber composition is 91 to 93% by mass. While having such a high content of ferrite magnetic powder (B), the fluidity is good, which is a major feature of the magnetic rubber composition of the present invention. A magnetic rubber molded product obtained by vulcanizing such a magnetic rubber composition has an extremely high residual magnetic flux density and also has good mechanical properties. When the content of the ferrite magnetic powder (B) is less than 91% by mass, the residual magnetic flux density is lowered. The content of the ferrite magnetic powder (B) is preferably 91.3% by mass or more, and more preferably 91.6% by mass or more. On the other hand, when the content of the ferrite magnetic powder (B) exceeds 93% by mass, moldability deteriorates, poor filling into the mold occurs, and the strength of the obtained magnetic rubber molded product decreases.
本発明の磁性ゴム組成物は、本発明の効果を阻害しない範囲であれば、ＨＮＢＲ（Ａ）、フェライト磁性粉（Ｂ）、加硫剤（Ｃ）及びステアリン酸（Ｄ）以外の成分を含んでいても構わない。磁性ゴム組成物において通常使用される、加硫促進剤、加硫助剤、受酸剤、着色剤、フィラー、可塑剤など、各種の添加剤を含むことができる。ただし、このような他の成分を多量に含んでいたのでは、フェライト磁性粉（Ｂ）の含有率を９１質量％以上にすることができないので、他の成分の含有量が多すぎないことが重要である。 The magnetic rubber composition of the present invention contains components other than HNBR (A), ferrite magnetic powder (B), vulcanizing agent (C) and stearic acid (D) as long as the effects of the present invention are not impaired. It does not matter. Various additives such as a vulcanization accelerator, a vulcanization aid, an acid acceptor, a colorant, a filler, and a plasticizer that are usually used in the magnetic rubber composition can be contained. However, if such other components are contained in a large amount, the content of the ferrite magnetic powder (B) cannot be 91% by mass or more, so the content of other components may not be too much. is important.
以上のようにして得られた磁性ゴム組成物を加硫することで本発明の磁性ゴム成形品を得ることができる。具体的には、ＨＮＢＲ（Ａ）、フェライト磁性粉（Ｂ）、加硫剤（Ｃ）及びステアリン酸（Ｄ）を混合して前記磁性ゴム組成物を得てから、金型中で加硫することによって、磁性ゴム成形品を得ることができる。 The magnetic rubber composition of the present invention can be obtained by vulcanizing the magnetic rubber composition obtained as described above. Specifically, HNBR (A), ferrite magnetic powder (B), vulcanizing agent (C) and stearic acid (D) are mixed to obtain the magnetic rubber composition, and then vulcanized in a mold. Thus, a magnetic rubber molded product can be obtained.
まず、上記各成分を混合することによって磁性ゴム組成物が製造される。混合する方法は特に限定されず、オープンロール、ニーダ、バンバリーミキサ、インターミキサ、押出機などを用いて混練する方法が採用される。なかでも、オープンロール又はニーダを用いて混練することが好ましい。混練時の磁性ゴム組成物の温度は６０〜１３０℃とすることが好ましい。混練時間は、１０〜６０分であることが好ましい。このように、比較的低温で高粘度の組成物を比較的長時間混練してから加硫に供するのが、ゴム成形品を製造する際の通常の方法である。しかしながら、フェライト磁性粉を大量に含む場合には、流動性を確保することが特に重要である。 First, a magnetic rubber composition is produced by mixing the above components. The mixing method is not particularly limited, and a kneading method using an open roll, a kneader, a Banbury mixer, an intermixer, an extruder, or the like is employed. Especially, it is preferable to knead | mix using an open roll or a kneader. The temperature of the magnetic rubber composition during kneading is preferably 60 to 130 ° C. The kneading time is preferably 10 to 60 minutes. Thus, kneading a composition having a relatively low temperature and high viscosity for a relatively long time and then subjecting it to vulcanization is the usual method for producing a rubber molded article. However, it is particularly important to ensure fluidity when a large amount of ferrite magnetic powder is contained.
こうして得られた磁性ゴム組成物の１８０℃における加硫曲線を測定した際のトルクの最小値ＭＬが、３〜８ｋｇｆ・ｃｍであることが好ましい。ＭＬが８ｋｇｆ・ｃｍを超える場合には、成形性が不十分になって充填不足となるおそれがある。ＭＬは、より好適には６ｋｇｆ・ｃｍ以下である。特に流動性が要求される形状の成形品を製造する場合には、ＭＬが５．５ｋｇｆ・ｃｍ以下であることが好ましい場合もある。一方、ＭＬが３ｋｇｆ・ｃｍ未満の場合には、成形品の機械強度が低下するおそれがあるとともに、成形品にエアが残るおそれもある。ＭＬは、より好適には３．５ｋｇｆ・ｃｍ以上である。特に機械強度が要求される用途の成形品を製造する場合には、ＭＬが４．２ｋｇｆ・ｃｍ以上であることが好ましい場合もある。 The minimum torque ML when the vulcanization curve at 180 ° C. of the magnetic rubber composition thus obtained is measured is preferably 3 to 8 kgf · cm. If ML exceeds 8 kgf · cm, the moldability may be insufficient and filling may be insufficient. ML is more preferably 6 kgf · cm or less. In particular, when a molded product having a shape requiring fluidity is produced, it may be preferable that ML is 5.5 kgf · cm or less. On the other hand, when ML is less than 3 kgf · cm, the mechanical strength of the molded product may be lowered and air may remain in the molded product. ML is more preferably 3.5 kgf · cm or more. In particular, when a molded product for use requiring mechanical strength is produced, it may be preferable that ML is 4.2 kgf · cm or more.
引き続き、磁性ゴム組成物を金型中で成形するとともに加硫して磁性ゴム成形品を得る。通常、上記磁性ゴム組成物を所望の形状に成形し、加熱することにより加硫する。磁性ゴム組成物の成形方法としては、押出成形、圧縮成形などが挙げられる。中でも圧縮成形が好適である。加硫温度は、１４０〜２５０℃であることが好ましい。加硫時間は、１〜３０分であることが好ましい。また、磁性ゴム成形品の形状や寸法などによっては、表面が加硫されていても内部まで十分に加硫されていない場合があるので、さらに加熱して二次加硫を行ってもよい。加硫するための加熱方法としては、圧縮加熱、スチーム加熱、オーブン加熱、熱風加熱などの、ゴムの加硫に用いられる一般的な方法が用いられるが、圧縮加熱が好適である。 Subsequently, the magnetic rubber composition is molded in a mold and vulcanized to obtain a magnetic rubber molded product. Usually, the magnetic rubber composition is molded into a desired shape and vulcanized by heating. Examples of the molding method of the magnetic rubber composition include extrusion molding and compression molding. Of these, compression molding is preferred. The vulcanization temperature is preferably 140 to 250 ° C. The vulcanization time is preferably 1 to 30 minutes. Further, depending on the shape and dimensions of the magnetic rubber molded product, even if the surface is vulcanized, it may not be sufficiently vulcanized to the inside. Therefore, secondary vulcanization may be performed by further heating. As a heating method for vulcanization, general methods used for rubber vulcanization such as compression heating, steam heating, oven heating, hot air heating and the like are used, and compression heating is preferable.
本発明の製造方法では、磁場の印加された金型中で加硫することが好ましい。これにより、磁性ゴム成形品の残留磁束密度を高めることができる。このとき、圧縮成形する際に、成形品の表面に垂直な方向の磁場を印加することが好適である。本発明の樹脂組成物は、多量のフェライト磁性粉を含んでいるにもかかわらず流動性が良好であり、磁場の印加された金型中で加硫することによってフェライト磁性粉が高度に配向して、極めて高い残留磁束密度を示すことができる。 In the production method of the present invention, vulcanization is preferably performed in a mold to which a magnetic field is applied. Thereby, the residual magnetic flux density of the magnetic rubber molded product can be increased. At this time, when compression molding, it is preferable to apply a magnetic field in a direction perpendicular to the surface of the molded product. The resin composition of the present invention has good fluidity despite containing a large amount of ferrite magnetic powder, and the ferrite magnetic powder is highly oriented by vulcanization in a mold to which a magnetic field is applied. Thus, a very high residual magnetic flux density can be shown.
本発明の磁気エンコーダは、以上のようにして得られた磁性ゴム成形品が着磁されてなる磁性体を備えたものである。当該磁性体は、Ｓ極及びＮ極を１組だけ有するものであっても構わないが、多くの場合、交互に磁極が配置された多極磁性体である。ただし、着磁態様はこれらに限られるものではない。当該磁性体の形状は特に限定されないが、回転運動を検出する際には、円盤状あるいは円筒状など、環状であることが好ましい。この場合には、Ｓ極とＮ極が円周方向に交互に配置されて角度を検出することができ、実用上最も重要な態様である。一方、直線運動を検出する用途などでは、平坦な帯状の磁性体であっても構わない。Ｓ極とＮ極が接近して形成され、各極の寸法が小さい場合に、高い残留磁束密度が要求されるので、本発明の方法で製造される磁気エンコーダを採用する利益が大きい。 The magnetic encoder of the present invention includes a magnetic body formed by magnetizing the magnetic rubber molded product obtained as described above. The magnetic body may have only one set of S pole and N pole, but in many cases, it is a multipolar magnetic body in which magnetic poles are alternately arranged. However, the magnetization mode is not limited to these. The shape of the magnetic body is not particularly limited, but it is preferably an annular shape such as a disk shape or a cylindrical shape when detecting a rotational motion. In this case, the S pole and the N pole are alternately arranged in the circumferential direction and the angle can be detected, which is the most important aspect in practical use. On the other hand, for applications such as detecting linear motion, a flat belt-like magnetic material may be used. When the S pole and the N pole are formed close to each other and the dimensions of each pole are small, a high residual magnetic flux density is required, so that there is a great advantage in adopting the magnetic encoder manufactured by the method of the present invention.
本発明の磁気エンコーダは、必要に応じて当該磁性体を支持する支持部材を備える。当該支持部材は、金属部材、特に金属板であることが好ましい。磁性ゴム成形品と支持部材との接着方法は特に限定されず、磁性ゴム成形品を加硫する際に直接そのまま両者を接着しても構わない。しかしながら、本発明の磁性ゴム組成物を支持部材により強固に接着するためには、磁性ゴム成形品と前記支持部材とを、熱硬化性接着剤で接着することが好ましい。この場合、磁性ゴム組成物を成形して加硫させた後に熱硬化性接着剤を硬化させて、磁性ゴム成形品を熱硬化性接着剤で支持部材に固着させてもよいし、磁性ゴム組成物を成形して加硫させるのと同時に熱硬化性接着剤を硬化させて、磁性ゴム成形品を熱硬化性接着剤で支持部材に固着させてもよい。ここで用いられる熱硬化性接着剤は、熱によって架橋反応が進行して硬化するタイプの接着剤であれば特に限定されない。フェノール樹脂、エポキシ樹脂、ウレタン樹脂、未加硫ゴムを溶剤に溶かしたゴム糊、シランカップリング剤などを用いることができる。 The magnetic encoder of the present invention includes a support member that supports the magnetic body as necessary. The support member is preferably a metal member, particularly a metal plate. The bonding method between the magnetic rubber molded product and the support member is not particularly limited, and both may be directly bonded when the magnetic rubber molded product is vulcanized. However, in order to firmly bond the magnetic rubber composition of the present invention to the support member, it is preferable to bond the magnetic rubber molded product and the support member with a thermosetting adhesive. In this case, after molding and vulcanizing the magnetic rubber composition, the thermosetting adhesive may be cured, and the magnetic rubber molded product may be fixed to the support member with the thermosetting adhesive. The thermosetting adhesive may be cured at the same time that the product is molded and vulcanized, and the magnetic rubber molded article may be fixed to the support member with the thermosetting adhesive. The thermosetting adhesive used here is not particularly limited as long as it is a type of adhesive that cures by a crosslinking reaction caused by heat. A phenol resin, an epoxy resin, a urethane resin, a rubber paste in which an unvulcanized rubber is dissolved in a solvent, a silane coupling agent, or the like can be used.
本発明の方法で製造される磁気エンコーダの好適な実施態様は、回転体に取り付け可能な支持部材と、該支持部材に装着された環状の磁性ゴム成形品を備え、該磁性ゴム成形品がＮ極とＳ極とが円周方向に交互に着磁された磁気エンコーダである。これは、回転運動を検出する磁気エンコーダとして有用である。細かい角度を精度よく測定する場合などに、高い残留磁束密度を有する磁性ゴム成形品を備えた磁気エンコーダを採用する利益が大きい。 A preferred embodiment of the magnetic encoder manufactured by the method of the present invention includes a support member that can be attached to a rotating body, and an annular magnetic rubber molded product mounted on the support member, and the magnetic rubber molded product is N This is a magnetic encoder in which poles and S poles are alternately magnetized in the circumferential direction. This is useful as a magnetic encoder that detects rotational motion. There is a great advantage in adopting a magnetic encoder provided with a magnetic rubber molded product having a high residual magnetic flux density when measuring a fine angle with high accuracy.
本発明の方法で製造される磁気エンコーダの用途は特に限定されない。磁気エンコーダのうち、周方向に交互に磁極が配置された環状又は円盤状の多極磁性体を含むものは、回転運動を検出するセンサに用いられる。例えば、車軸の回転速度検出装置、クランク角検出装置、モーターの回転角度検出装置などに用いられる。また、直線方向に交互に磁極が配置された多極磁性体を含むものは、直線運動を検出するセンサに用いられる。例えば、リニアガイド装置、パワーウインドウ、パワーシート、ブレーキ踏み込み量検出装置、事務機器などに用いられる。中でも、車両用アンチロックブレーキシステムのセンサーローター用の磁気エンコーダとして用いることが、磁気特性と機械特性に優れ、残留磁束密度が極めて高い本発明の方法で製造される磁気エンコーダの最も有用な用途である。 The application of the magnetic encoder manufactured by the method of the present invention is not particularly limited. Among magnetic encoders, one that includes an annular or disk-shaped multipolar magnetic body in which magnetic poles are alternately arranged in the circumferential direction is used for a sensor that detects rotational motion. For example, it is used for an axle rotation speed detection device, a crank angle detection device, a motor rotation angle detection device, and the like. Moreover, what contains the multipolar magnetic body by which the magnetic pole is alternately arrange | positioned in a linear direction is used for the sensor which detects a linear motion. For example, it is used for a linear guide device, a power window, a power seat, a brake depression amount detection device, office equipment, and the like. Among them, the magnetic encoder used for the sensor rotor of the vehicle anti-lock brake system is the most useful application of the magnetic encoder manufactured by the method of the present invention having excellent magnetic characteristics and mechanical characteristics and extremely high residual magnetic flux density. is there.
実施例１
［未加硫ゴムシートの作製］
以下に示す原料を、８インチ径のオープンロールを用いて、組成物の温度を６０〜１００℃に維持して３５分間混練し、厚さ１ｍｍ、１．５ｍｍ及び２ｍｍの未加硫ゴムシートを作製した。
・水素添加ニトリルゴム（ＨＮＢＲ）：１００質量部
アクリロニトリル含有量３６．２質量％、ムーニー粘度（ＭＬ１＋４、１００℃）５７．５、ヨウ素価１１ｇ／１００ｇ。
・ストロンチウムフェライト磁性粉Ａ（磁場配向用）：１３５０質量部
平均粒子径１．２μｍ（粒度分布において複数のピークを有する。）
圧縮密度３．６ｇ／ｃｍ３
圧縮体の残留磁束密度１９６ｍＴ
圧縮体の保磁力２３６ｋＡ／ｍ
・可塑剤ＴＯＴＭ［トリメリット酸トリス（２−エチルへキシル）］：３質量部
・亜鉛華：５質量部
・ステアリン酸：３．５質量部
・老化防止剤［４，４’−ビス（α，α−ジメチルベンジル）ジフェニルアミン］：５質量部
・硫黄：０．４質量部
・加硫促進剤ＭＢＴＳ（２，２’−ジベンゾチアゾリルジスルフィド）：２質量部
・加硫促進剤ＴＥＴＤ（テトラエチルチウラムジスルフィド）：１．５質量部
Example 1
[Preparation of unvulcanized rubber sheet]
The raw materials shown below were kneaded for 35 minutes while maintaining the temperature of the composition at 60 to 100 ° C. using an 8-inch diameter open roll, and unvulcanized rubber sheets having thicknesses of 1 mm, 1.5 mm and 2 mm were obtained. Produced.
Hydrogenated nitrile rubber (HNBR): 100 parts by mass An acrylonitrile content of 36.2% by mass, a Mooney viscosity (ML 1 + 4 , 100 ° C.) of 57.5, and an iodine value of 11 g / 100 g.
Strontium ferrite magnetic powder A (for magnetic field orientation): 1350 parts by mass Average particle size: 1.2 μm (having a plurality of peaks in the particle size distribution)
Compression density 3.6 g / cm 3
Residual magnetic flux density of compressed body 196mT
Coercive force of compressed body 236 kA / m
Plasticizer TOTM [trimellitic acid tris (2-ethylhexyl)]: 3 parts by mass Zinc flower: 5 parts by mass Stearic acid: 3.5 parts by mass Antiaging agent [4,4′-bis (α , Α-dimethylbenzyl) diphenylamine]: 5 parts by mass, sulfur: 0.4 parts by mass, vulcanization accelerator MBTS (2,2′-dibenzothiazolyl disulfide): 2 parts by mass, vulcanization accelerator TETD (tetraethyl) Thiuram disulfide): 1.5 parts by mass
［加硫特性］
得られた未加硫ゴムシートを試料とし、ＪＩＳ Ｋ６３００−２に準拠し、株式会社エー・アンド・デイ製の「キュラストメーター７」を用いて測定した。測定温度１８０℃で５分間の加硫曲線を測定し、縦軸をトルク、横軸を時間としたグラフのトルクの最小値ＭＬ（ｋｇｆ・ｃｍ）、最大値ＭＨ（ｋｇｆ・ｃｍ）、ＭＨの１０％のトルクになるまでの時間Ｔ１０（分）及びＭＨの９０％のトルクになるまでの時間Ｔ９０（分）を求めた。その結果、Ｔ１０が１．５５分、Ｔ９０が２．９８分、ＭＬが５．５２ｋｇｆ・ｃｍ及びＭＨが４６．９２ｋｇｆ・ｃｍであった。
[Vulcanization characteristics]
The obtained unvulcanized rubber sheet was used as a sample, and measurement was performed using “Curalast Meter 7” manufactured by A & D Co., Ltd. in accordance with JIS K6300-2. A vulcanization curve for 5 minutes at a measurement temperature of 180 ° C. is measured, and the minimum value ML (kgf · cm), maximum value MH (kgf · cm), MH of the torque in the graph with the vertical axis representing torque and the horizontal axis representing time. A time T10 (min) until the torque reaches 10% and a time T90 (min) until the torque reaches 90% of MH were obtained. As a result, T10 was 1.55 minutes, T90 was 2.98 minutes, ML was 5.52 kgf · cm, and MH was 46.92 kgf · cm.
［機械特性］
ＪＩＳ Ｋ６２５１に準拠して引張試験を行った。得られた未加硫ゴムシートを用い１７０℃で１０分間プレス加硫して厚さ１ｍｍの加硫ゴムシートを得た。得られた加硫ゴムシートを打ち抜いて得られた、ダンベル状３号形の試験片を用い、２３℃、相対湿度５０％において、引張速度５００ｍｍ／分の引張速度で、引張強さ（ＭＰａ）と伸び（％）を測定した。その結果、引張強さは９．０ＭＰａであり、伸びは１６％であった。
[Mechanical properties]
A tensile test was performed according to JIS K6251. The obtained unvulcanized rubber sheet was press vulcanized at 170 ° C. for 10 minutes to obtain a vulcanized rubber sheet having a thickness of 1 mm. Using a dumbbell-shaped No. 3 test piece obtained by punching the obtained vulcanized rubber sheet, tensile strength (MPa) at 23 ° C. and 50% relative humidity at a tensile rate of 500 mm / min. And elongation (%) was measured. As a result, the tensile strength was 9.0 MPa and the elongation was 16%.
［硬度］
ＪＩＳ Ｋ６２５３に準拠して測定した。引張試験と同様に作製した厚さ２ｍｍの加硫ゴムシートを３枚重ね、タイプＡデュロメータを用いて、２３℃、相対湿度５０％において測定を行い、ピーク値を読み取った。その結果、Ａ硬度は９８であった。
[hardness]
The measurement was performed according to JIS K6253. Three vulcanized rubber sheets with a thickness of 2 mm produced in the same manner as in the tensile test were stacked, measured using a type A durometer at 23 ° C. and 50% relative humidity, and the peak value was read. As a result, the A hardness was 98.
［磁気特性］
得られた未加硫ゴムシートを用い、直径１８ｍｍ、厚さ６ｍｍの円盤状試験片を作成し、試験片の厚み方向に磁場をかけながら、１７０℃で１０分間プレス加硫して加硫ゴム試験片を得た。得られた成形品の残留磁束密度及び保磁力を、メトロン技研株式会社製の直流磁化特性試験装置「ＢＨカーブトレーサー」によって測定した。その結果、残留磁束密度は３３８ｍＴであった。
[Magnetic properties]
Using the obtained unvulcanized rubber sheet, a disk-shaped test piece having a diameter of 18 mm and a thickness of 6 mm was prepared, and vulcanized rubber was press-vulcanized at 170 ° C. for 10 minutes while applying a magnetic field in the thickness direction of the test piece. A specimen was obtained. The residual magnetic flux density and coercive force of the obtained molded product were measured by a DC magnetism characteristic test apparatus “BH curve tracer” manufactured by Metron Giken Co., Ltd. As a result, the residual magnetic flux density was 338 mT.
［支持部材への接着性］
支持部材（スリンガ）として、板厚０．６ｍｍのＳＵＳ４３０からなる、断面Ｌ字型で円環状のものを用いた。当該支持部材の寸法は、内径側円筒部の内径が５５ｍｍ、外側円輪部の外径が６７ｍｍ、内径円筒部の軸方向長さが４．０ｍｍであった。一方、得られた厚さ１．５ｍｍの未加硫ゴムシートを、内径５６ｍｍ、外径６７ｍｍのドーナツ状に打ち抜いて、フェノール樹脂を原料とする接着剤を予め塗布した支持部材上に載置した。引き続き、１８０℃で３分間プレス加硫して、内径５６ｍｍ、外径６７ｍｍ、厚さ１．０ｍｍの磁性体を形成した。当該磁性体は支持部材に強固に接着しており、接着性は良好であった。また、金型からの離型性も良好であった。以上の結果を表１にまとめて示す。
[Adhesiveness to support member]
As the support member (slinger), an annular member having an L-shaped cross section made of SUS430 having a plate thickness of 0.6 mm was used. Regarding the dimensions of the support member, the inner diameter of the inner cylindrical portion was 55 mm, the outer diameter of the outer ring portion was 67 mm, and the axial length of the inner cylindrical portion was 4.0 mm. On the other hand, the obtained unvulcanized rubber sheet having a thickness of 1.5 mm was punched out into a donut shape having an inner diameter of 56 mm and an outer diameter of 67 mm, and placed on a support member preliminarily coated with an adhesive made of phenol resin. . Subsequently, press vulcanization was performed at 180 ° C. for 3 minutes to form a magnetic body having an inner diameter of 56 mm, an outer diameter of 67 mm, and a thickness of 1.0 mm. The magnetic body was firmly adhered to the support member, and the adhesion was good. Moreover, the releasability from the mold was also good. The above results are summarized in Table 1.
実施例２
実施例１において、ステアリン酸の配合量を４．５質量部にした以外は実施例１と同様にして、未加硫ゴムシートを作製した。得られた未加硫ゴムシートを用いて実施例１と同様にして、加硫特性、磁気特性、支持部材への接着性、及び離型性を評価した。結果を表１にまとめて示す。
Example 2
In Example 1, an unvulcanized rubber sheet was produced in the same manner as in Example 1 except that the amount of stearic acid was 4.5 parts by mass. Using the obtained unvulcanized rubber sheet, vulcanization characteristics, magnetic characteristics, adhesion to a support member, and mold release properties were evaluated in the same manner as in Example 1. The results are summarized in Table 1.
比較例１
実施例１において、ステアリン酸の配合量を１質量部にした以外は実施例１と同様にして、未加硫ゴムシートを作製した。得られた未加硫ゴムシートを用いて実施例１と同様にして、加硫特性、磁気特性、支持部材への接着性、及び離型性を評価した。結果を表１にまとめて示す。
Comparative Example 1
In Example 1, an unvulcanized rubber sheet was prepared in the same manner as in Example 1 except that the amount of stearic acid was 1 part by mass. Using the obtained unvulcanized rubber sheet, vulcanization characteristics, magnetic characteristics, adhesion to a support member, and mold release properties were evaluated in the same manner as in Example 1. The results are summarized in Table 1.
比較例２
比較例１において、ストロンチウムフェライト磁性粉Ａの配合量を１１００質量部にした以外は比較例１と同様にして、未加硫ゴムシートを作製した。得られた未加硫ゴムシートを用いて実施例１と同様にして、加硫特性、磁気特性、支持部材への接着性、及び離型性を評価した。結果を表１にまとめて示す。
Comparative Example 2
In Comparative Example 1, an unvulcanized rubber sheet was produced in the same manner as Comparative Example 1 except that the amount of strontium ferrite magnetic powder A was 1100 parts by mass. Using the obtained unvulcanized rubber sheet, vulcanization characteristics, magnetic characteristics, adhesion to a support member, and mold release properties were evaluated in the same manner as in Example 1. The results are summarized in Table 1.
比較例３
実施例１において、水素添加ニトリルゴム（ＨＮＢＲ）の代わりにニトリルゴム（ＮＢＲ）を用いた以外は実施例１と同様にして、未加硫ゴムシートを作製した。ここで用いたＮＢＲの特性は下記の通りである。得られた未加硫ゴムシートを用いて実施例１と同様にして、加硫特性、磁気特性、支持部材への接着性、及び離型性を評価した。結果を表１にまとめて示す。
アクリロニトリル含有量３３質量％
ムーニー粘度（ＭＬ１＋４、１００℃）４５
Comparative Example 3
In Example 1, an unvulcanized rubber sheet was produced in the same manner as in Example 1 except that nitrile rubber (NBR) was used instead of hydrogenated nitrile rubber (HNBR). The characteristics of the NBR used here are as follows. Using the obtained unvulcanized rubber sheet, vulcanization characteristics, magnetic characteristics, adhesion to a support member, and mold release properties were evaluated in the same manner as in Example 1. The results are summarized in Table 1.
Acrylonitrile content 33% by mass
Mooney viscosity (ML 1 + 4 , 100 ° C.) 45
比較例４
比較例２において、水素添加ニトリルゴム（ＨＮＢＲ）の代わりにニトリルゴム（ＮＢＲ）を用いた以外は比較例２と同様にして、未加硫ゴムシートを作製した。得られた未加硫ゴムシートを用いて実施例１と同様にして、加硫特性、磁気特性、支持部材への接着性、及び離型性を評価した。結果を表１にまとめて示す。
Comparative Example 4
In Comparative Example 2, an unvulcanized rubber sheet was produced in the same manner as in Comparative Example 2 except that nitrile rubber (NBR) was used instead of hydrogenated nitrile rubber (HNBR). Using the obtained unvulcanized rubber sheet, vulcanization characteristics, magnetic characteristics, adhesion to a support member, and mold release properties were evaluated in the same manner as in Example 1. The results are summarized in Table 1.
表１から、実施例１、２及び比較例１の対比から、ステアリン酸の配合量が増加すると、ＭＬが低下して流動性が良好になるとともに、加硫時に印加する磁場によってフェライト粒子が配向しやすくなり、残留磁束密度が大きくなることがわかった。ただし、ステアリン酸が多すぎると、強度が低下する傾向が認められた。また、実施例１と比較例３の対比から、ＨＮＢＲをＮＢＲに変更することによって、ＭＬが増大し流動性が低下することがわかった。その結果成形性が悪化したのみならず、磁場配向性も悪化して残留磁束密度が低下した。
From Table 1, from the comparison between Examples 1 and 2 and Comparative Example 1, when the amount of stearic acid increases, ML decreases and fluidity improves, and ferrite particles are oriented by a magnetic field applied during vulcanization. It was found that the residual magnetic flux density was increased. However, when there was too much stearic acid, the tendency for intensity | strength to fall was recognized. Moreover, it turned out that ML increases and fluidity | liquidity falls by changing HNBR into NBR from the comparison of Example 1 and Comparative Example 3. As a result, not only the formability deteriorated, but also the magnetic field orientation deteriorated and the residual magnetic flux density decreased.
Claims (10)
水素化ニトリルゴム（Ａ）のムーニー粘度（ＭＬ１＋４、１００℃）が４５〜８０であり、
水素化ニトリルゴム（Ａ）１００質量部に対し、フェライト磁性粉（Ｂ）１２５０〜１６００質量部、加硫剤（Ｃ）０．１〜４質量部及びステアリン酸（Ｄ）２．５〜８質量部を含有し、
前記磁性ゴム組成物全体の質量に対するフェライト磁性粉（Ｂ）の含有率が９１〜９３質量％であることを特徴とする磁性ゴム組成物。 A magnetic rubber composition containing hydrogenated nitrile rubber (A), ferrite magnetic powder (B), vulcanizing agent (C) and stearic acid (D),
The Mooney viscosity (ML 1 + 4 , 100 ° C.) of the hydrogenated nitrile rubber (A) is 45-80,
Ferrite magnetic powder (B) 1250 to 1600 parts by mass, vulcanizing agent (C) 0.1 to 4 parts by mass and stearic acid (D) 2.5 to 8 parts by mass with respect to 100 parts by mass of hydrogenated nitrile rubber (A). Part
The magnetic rubber composition, wherein the content of the ferrite magnetic powder (B) is 91 to 93% by mass with respect to the total mass of the magnetic rubber composition.
A method for manufacturing a magnetic encoder, wherein a magnetic rubber molded product obtained by the method according to claim 8 or 9 is magnetized in a predetermined pattern.
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